The nurse's load: early-life exposure to brood-rearing affects behavior and lifespan in honey bees (Apis mellifera).

PubMed

Amdam, Gro V; Rueppell, Olav; Fondrk, M Kim; Page, Robert E; Nelson, C Mindy

2009-01-01

Long-lived honey bees (Apis mellifera) develop in fall. This pattern may be explained by reduced nurse loads. When the amount of brood in colonies declines as a function of adverse foraging conditions, adult bees build up surplus nutrient stores that include vitellogenin, a behavioral affector protein that also can increase lifespan. Although the seasonal reduction in exposure to nursing tasks predictably results in vitellogenin accumulation, the assumption that long-lived adults thereby develop is confounded by a concomitant decline in foraging effort. Foraging activity reduces lifespan, and is influenced by colony resource consumption, brood pheromones, availability of nectar and pollen, and weather. Here, we perform the first controlled experiment where the nursing environment of pre-foraging sister bees was set to vary, while their foraging environment later was set to be the same. We measure vitellogenin, age at foraging onset and lifespan. We establish that reduced brood-rearing increases vitellogenin levels, and delays foraging onset and death. Longevity is largely explained by the effect of nursing on the onset of foraging behavior, but is also influenced by the level of brood-rearing independent of behavioral change. Our findings are consistent with the roles of vitellogenin in regulation of honey bee behavior and lifespan.

Variation in body condition during the post-moult foraging trip of southern elephant seals and its consequences on diving behaviour.

PubMed

Richard, Gaëtan; Vacquié-Garcia, Jade; Jouma'a, Joffrey; Picard, Baptiste; Génin, Alexandre; Arnould, John P Y; Bailleul, Frédéric; Guinet, Christophe

2014-07-15

Mature female southern elephant seals (Mirounga leonina) come ashore only in October to breed and in January to moult, spending the rest of the year foraging at sea. Mature females may lose as much as 50% of their body mass, mostly in lipid stores, during the breeding season due to fasting and lactation. When departing to sea, post-breeding females are negatively buoyant, and the relative change in body condition (i.e. density) during the foraging trip has previously been assessed by monitoring the descent rate during drift dives. However, relatively few drift dives are performed, resulting in low resolution of the temporal reconstruction of body condition change. In this study, six post-breeding females were equipped with time-depth recorders and accelerometers to investigate whether changes in active swimming effort and speed could be used as an alternative method of monitoring density variations throughout the foraging trip. In addition, we assessed the consequences of density change on the swimming efforts of individuals while diving and investigated the effects on dive duration. Both descent swimming speed and ascent swimming effort were found to be strongly correlated to descent rate during drift dives, enabling the fine-scale monitoring of seal density change over the whole trip. Negatively buoyant seals minimized swimming effort during descents, gliding down at slower speeds, and reduced their ascent swimming effort to maintain a nearly constant swimming speed as their buoyancy increased. One per cent of seal density variation over time was found to induce a 20% variation in swimming effort during dives with direct consequences on dive duration. © 2014. Published by The Company of Biologists Ltd.

Group foraging increases foraging efficiency in a piscivorous diver, the African penguin

PubMed Central

McGeorge, Cuan; Ginsberg, Samuel; Pichegru, Lorien; Pistorius, Pierre A.

2017-01-01

Marine piscivores have evolved a variety of morphological and behavioural adaptations, including group foraging, to optimize foraging efficiency when targeting shoaling fish. For penguins that are known to associate at sea and feed on these prey resources, there is nonetheless a lack of empirical evidence to support improved foraging efficiency when foraging with conspecifics. We examined the hunting strategies and foraging performance of breeding African penguins equipped with animal-borne video recorders. Individuals pursued both solitary as well as schooling pelagic fish, and demonstrated independent as well as group foraging behaviour. The most profitable foraging involved herding of fish schools upwards during the ascent phase of a dive where most catches constituted depolarized fish. Catch-per-unit-effort was significantly improved when targeting fish schools as opposed to single fish, especially when foraging in groups. In contrast to more generalist penguin species, African penguins appear to have evolved specialist hunting strategies closely linked to their primary reliance on schooling pelagic fish. The specialist nature of the observed hunting strategies further limits the survival potential of this species if Allee effects reduce group size-related foraging efficiency. This is likely to be exacerbated by diminishing fish stocks due to resource competition and environmental change. PMID:28989785

Spatial Heterogeneity in the Strength of Plant-Herbivore Interactions under Predation Risk: The Tale of Bison Foraging in Wolf Country

PubMed Central

Harvey, Léa; Fortin, Daniel

2013-01-01

Spatial heterogeneity in the strength of trophic interactions is a fundamental property of food web spatial dynamics. The feeding effort of herbivores should reflect adaptive decisions that only become rewarding when foraging gains exceed 1) the metabolic costs, 2) the missed opportunity costs of not foraging elsewhere, and 3) the foraging costs of anti-predator behaviour. Two aspects of these costs remain largely unexplored: the link between the strength of plant-herbivore interactions and the spatial scale of food-quality assessment, and the predator-prey spatial game. We modeled the foraging effort of free-ranging plains bison (Bison bison bison) in winter, within a mosaic of discrete meadows. Spatial patterns of bison herbivory were largely driven by a search for high net energy gains and, to a lesser degree, by the spatial game with grey wolves (Canis lupus). Bison decreased local feeding effort with increasing metabolic and missed opportunity costs. Bison herbivory was most consistent with a broad-scale assessment of food patch quality, i.e., bison grazed more intensively in patches with a low missed opportunity cost relative to other patches available in the landscape. Bison and wolves had a higher probability of using the same meadows than expected randomly. This co-occurrence indicates wolves are ahead in the spatial game they play with bison. Wolves influenced bison foraging at fine scale, as bison tended to consume less biomass at each feeding station when in meadows where the risk of a wolf's arrival was relatively high. Also, bison left more high-quality vegetation in large than small meadows. This behavior does not maximize their energy intake rate, but is consistent with bison playing a shell game with wolves. Our assessment of bison foraging in a natural setting clarifies the complex nature of plant-herbivore interactions under predation risk, and reveals how spatial patterns in herbivory emerge from multi-scale landscape heterogeneity. PMID:24039909

Evidence for ship noise impacts on humpback whale foraging behaviour.

PubMed

Blair, Hannah B; Merchant, Nathan D; Friedlaender, Ari S; Wiley, David N; Parks, Susan E

2016-08-01

Noise from shipping activity in North Atlantic coastal waters has been steadily increasing and is an area of growing conservation concern, as it has the potential to disrupt the behaviour of marine organisms. This study examines the impacts of ship noise on bottom foraging humpback whales (Megaptera novaeangliae) in the western North Atlantic. Data were collected from 10 foraging whales using non-invasive archival tags that simultaneously recorded underwater movements and the acoustic environment at the whale. Using mixed models, we assess the effects of ship noise on seven parameters of their feeding behaviours. Independent variables included the presence or absence of ship noise and the received level of ship noise at the whale. We found significant effects on foraging, including slower descent rates and fewer side-roll feeding events per dive with increasing ship noise. During 5 of 18 ship passages, dives without side-rolls were observed. These findings indicate that humpback whales on Stellwagen Bank, an area with chronically elevated levels of shipping traffic, significantly change foraging activity when exposed to high levels of ship noise. This measureable reduction in within-dive foraging effort of individual whales could potentially lead to population-level impacts of shipping noise on baleen whale foraging success. © 2016 The Author(s).

Resiliency in forage and grazinglands

USDA-ARS?s Scientific Manuscript database

This manuscript is a combined effort of the speakers at the 2017 C6 Forage and Grazinglands Division Symposia which was titled “Resiliency in Forage and Grazinglands.” Developing more resilient agroecosystems, including those that produce forage and livestock, will become necessary to maintain agric...

Breeding short-tailed shearwaters buffer local environmental variability in south-eastern Australia by foraging in Antarctic waters.

PubMed

Berlincourt, Maud; Arnould, John P Y

2015-01-01

Establishing patterns of movements of free-ranging animals in marine ecosystems is crucial for a better understanding of their feeding ecology, life history traits and conservation. As central place foragers, the habitat use of nesting seabirds is heavily influenced by the resources available within their foraging range. We tested the prediction that during years with lower resource availability, short-tailed shearwaters (Puffinus tenuirostris) provisioning chicks should increase their foraging effort, by extending their foraging range and/or duration, both when foraging in neritic (short trips) and distant oceanic waters (long trips). Using both GPS and geolocation data-loggers, at-sea movements and habitat use were investigated over three breeding seasons (2012-14) at two colonies in southeastern Australia. Most individuals performed daily short foraging trips over the study period and inter-annual variations observed in foraging parameters where mainly due to few individuals from Griffith Island, performing 2-day trips in 2014. When performing long foraging trips, this study showed that individuals from both colonies exploited similar zones in the Southern Ocean. The results of this study suggest that individuals could increase their foraging range while exploiting distant feeding zones, which could indicate that short-tailed shearwaters forage in Antarctic waters not only to maintain their body condition but may also do so to buffer against local environmental stochasticity. Lower breeding performances were associated with longer foraging trips to distant oceanic waters in 2013 and 2014 indicating they could mediate reductions in food availability around the breeding colonies by extending their foraging range in the Southern Ocean. This study highlights the importance of foraging flexibility as a fundamental aspect of life history in coastal/pelagic marine central place foragers living in highly variable environments and how these foraging strategies are use to buffer this variability.

Relationship between brain plasticity, learning and foraging performance in honey bees.

PubMed

Cabirol, Amélie; Cope, Alex J; Barron, Andrew B; Devaud, Jean-Marc

2018-01-01

Brain structure and learning capacities both vary with experience, but the mechanistic link between them is unclear. Here, we investigated whether experience-dependent variability in learning performance can be explained by neuroplasticity in foraging honey bees. The mushroom bodies (MBs) are a brain center necessary for ambiguous olfactory learning tasks such as reversal learning. Using radio frequency identification technology, we assessed the effects of natural variation in foraging activity, and the age when first foraging, on both performance in reversal learning and on synaptic connectivity in the MBs. We found that reversal learning performance improved at foraging onset and could decline with greater foraging experience. If bees started foraging before the normal age, as a result of a stress applied to the colony, the decline in learning performance with foraging experience was more severe. Analyses of brain structure in the same bees showed that the total number of synaptic boutons at the MB input decreased when bees started foraging, and then increased with greater foraging intensity. At foraging onset MB structure is therefore optimized for bees to update learned information, but optimization of MB connectivity deteriorates with foraging effort. In a computational model of the MBs sparser coding of information at the MB input improved reversal learning performance. We propose, therefore, a plausible mechanistic relationship between experience, neuroplasticity, and cognitive performance in a natural and ecological context.

Balancing personal maintenance with parental investment in a chick-rearing seabird: physiological indicators change with foraging conditions.

PubMed

Storey, Anne E; Ryan, Morag G; Fitzsimmons, Michelle G; Kouwenberg, Amy-Lee; Takahashi, Linda S; Robertson, Gregory J; Wilhelm, Sabina I; McKay, Donald W; Herzberg, Gene R; Mowbray, Frances K; MacMillan, Luke; Walsh, Carolyn J

2017-01-01

Seabird parents use a conservative breeding strategy that favours long-term survival over intensive parental investment, particularly under harsh conditions. Here, we examine whether variation in several physiological indicators reflects the balance between parental investment and survival in common murres ( Uria aalge ) under a wide range of foraging conditions. Blood samples were taken from adults during mid-chick rearing from 2007 to 2014 and analysed for corticosterone (CORT, stress hormone), beta-hydroxybutyrate (BUTY, lipid metabolism reflecting ongoing mass loss), and haematocrit (reflecting blood oxygen capacity). These measures, plus body mass, were related to three levels of food availability (good, intermediate, and poor years) for capelin, the main forage fish for murres in this colony. Adult body mass and chick-feeding rates were higher in good years than in poor years and heavier murres were more likely to fledge a chick than lighter birds. Contrary to prediction, BUTY levels were higher in good years than in intermediate and poor years. Murres lose body mass just after their chicks hatch and these results for BUTY suggest that mass loss may be delayed in good years. CORT levels were higher in intermediate years than in good or poor years. Higher CORT levels in intermediate years may reflect the necessity of increasing foraging effort, whereas extra effort is not needed in good years and it is unlikely to increase foraging success in poor years. Haematocrit levels were higher in poor years than in good years, a difference that may reflect either their poorer condition or increased diving requirements when food is less available. Our long-term data set provided insight into how decisions about resource allocation under different foraging conditions are relating to physiological indicators, a relationship that is relevant to understanding how seabirds may respond to changes in marine ecosystems as ocean temperatures continue to rise.

Genetic diversity within honeybee colonies increases signal production by waggle-dancing foragers

PubMed Central

Mattila, Heather R; Burke, Kelly M; Seeley, Thomas D

2008-01-01

Recent work has demonstrated considerable benefits of intracolonial genetic diversity for the productivity of honeybee colonies: single-patriline colonies have depressed foraging rates, smaller food stores and slower weight gain relative to multiple-patriline colonies. We explored whether differences in the use of foraging-related communication behaviour (waggle dances and shaking signals) underlie differences in foraging effort of genetically diverse and genetically uniform colonies. We created three pairs of colonies; each pair had one colony headed by a multiply mated queen (inseminated by 15 drones) and one colony headed by a singly mated queen. For each pair, we monitored the production of foraging-related signals over the course of 3 days. Foragers in genetically diverse colonies had substantially more information available to them about food resources than foragers in uniform colonies. On average, in genetically diverse colonies compared with genetically uniform colonies, 36% more waggle dances were identified daily, dancers performed 62% more waggle runs per dance, foragers reported food discoveries that were farther from the nest and 91% more shaking signals were exchanged among workers each morning prior to foraging. Extreme polyandry by honeybee queens enhances the production of worker–worker communication signals that facilitate the swift discovery and exploitation of food resources. PMID:18198143

Ocean climate and seal condition.

PubMed

Le Boeuf, Burney J; Crocker, Daniel E

2005-03-28

The condition of many marine mammals varies with fluctuations in productivity and food supply in the ocean basin where they forage. Prey is impacted by physical environmental variables such as cyclic warming trends. The weaning weight of northern elephant seal pups, Mirounga angustirostris, being closely linked to maternal condition, indirectly reflects prey availability and foraging success of pregnant females in deep waters of the northeastern Pacific. The aim of this study was to examine the effect of ocean climate on foraging success in this deep-diving marine mammal over the course of three decades, using cohort weaning weight as the principal metric of successful resource accrual. The mean annual weaning weight of pups declined from 1975 to the late 1990s, a period characterized by a large-scale, basin-wide warm decadal regime that included multiple strong or long-duration El Niños; and increased with a return to a cool decadal regime from about 1999 to 2004. Increased foraging effort and decreased mass gain of adult females, indicative of reduced foraging success and nutritional stress, were associated with high ocean temperatures. Despite ranging widely and foraging deeply in cold waters beyond coastal thermoclines in the northeastern Pacific, elephant seals are impacted significantly by ocean thermal dynamics. Ocean warming redistributes prey decreasing foraging success of females, which in turn leads to lower weaning mass of pups. Annual fluctuations in weaning mass, in turn, reflect the foraging success of females during the year prior to giving birth and signals changes in ocean temperature cycles.

What do foraging wasps optimize in a variable environment, energy investment or body temperature?

PubMed

Kovac, Helmut; Stabentheiner, Anton; Brodschneider, Robert

2015-11-01

Vespine wasps (Vespula sp.) are endowed with a pronounced ability of endothermic heat production. To show how they balance energetics and thermoregulation under variable environmental conditions, we measured the body temperature and respiration of sucrose foragers (1.5 M, unlimited flow) under variable ambient temperature (T a = 20-35 °C) and solar radiation (20-570 W m(-2)). Results revealed a graduated balancing of metabolic efforts with thermoregulatory needs. The thoracic temperature in the shade depended on ambient temperature, increasing from ~37 to 39 °C. However, wasps used solar heat gain to regulate their thorax temperature at a rather high level at low T a (mean T thorax ~ 39 °C). Only at high T a they used solar heat to reduce their metabolic rate remarkably. A high body temperature accelerated the suction speed and shortened foraging time. As the costs of foraging strongly depended on duration, the efficiency could be significantly increased with a high body temperature. Heat gain from solar radiation enabled the wasps to enhance foraging efficiency at high ambient temperature (T a = 30 °C) by up to 63 %. The well-balanced change of economic strategies in response to environmental conditions minimized costs of foraging and optimized energetic efficiency.

Sympatric cattle grazing and desert bighorn sheep foraging

USGS Publications Warehouse

Garrison, Kyle R.; Cain, James W.; Rominger, Eric M.; Goldstein, Elise J.

2015-01-01

Foraging behavior affects animal fitness and is largely dictated by the resources available to an animal. Understanding factors that affect forage resources is important for conservation and management of wildlife. Cattle sympatry is proposed to limit desert bighorn population performance, but few studies have quantified the effect of cattle foraging on bighorn forage resources or foraging behavior by desert bighorn. We estimated forage biomass for desert bighorn sheep in 2 mountain ranges: the cattle-grazed Caballo Mountains and the ungrazed San Andres Mountains, New Mexico. We recorded foraging bout efficiency of adult females by recording feeding time/step while foraging, and activity budgets of 3 age-sex classes (i.e., adult males, adult females, yearlings). We also estimated forage biomass at sites where bighorn were observed foraging. We expected lower forage biomass in the cattle-grazed Caballo range than in the ungrazed San Andres range and lower biomass at cattle-accessible versus inaccessible areas within the Caballo range. We predicted bighorn would be less efficient foragers in the Caballo range. Groundcover forage biomass was low in both ranges throughout the study (Jun 2012–Nov 2013). Browse biomass, however, was 4.7 times lower in the Caballo range versus the San Andres range. Bighorn in the Caballo range exhibited greater overall daily travel time, presumably to locate areas of higher forage abundance. By selecting areas with greater forage abundance, adult females in the Caballo range exhibited foraging bout efficiency similar to their San Andres counterparts but lower overall daily browsing time. We did not find a significant reduction in forage biomass at cattle-accessible areas in the Caballo range. Only the most rugged areas in the Caballo range had abundant forage, potentially a result of intensive historical livestock use in less rugged areas. Forage conditions in the Caballo range apparently force bighorn to increase foraging effort by feeding only in areas where adequate forage remains.

Evaluating the role of large jellyfish and forage fishes as energy pathways, and their interplay with fisheries, in the Northern Humboldt Current System

NASA Astrophysics Data System (ADS)

Chiaverano, Luciano M.; Robinson, Kelly L.; Tam, Jorge; Ruzicka, James J.; Quiñones, Javier; Aleksa, Katrina T.; Hernandez, Frank J.; Brodeur, Richard D.; Leaf, Robert; Uye, Shin-ichi; Decker, Mary Beth; Acha, Marcelo; Mianzan, Hermes W.; Graham, William M.

2018-05-01

Large jellyfish are important consumers of plankton, fish eggs and fish larvae in heavily fished ecosystems worldwide; yet they are seldom included in fisheries production models. Here we developed a trophic network model with 41 functional groups using ECOPATH re-expressed in a donor-driven, end-to-end format to directly evaluate the efficiency of large jellyfish and forage fish at transferring energy to higher trophic levels, as well as the ecosystem-wide effects of varying jellyfish and forage fish consumption rates and fishing rates, in the Northern Humboldt Current system (NHCS) off of Peru. Large jellyfish were an energy-loss pathway for high trophic-level consumers, while forage fish channelized the production of lower trophic levels directly into production of top-level consumers. A simulated jellyfish bloom resulted in a decline in productivity of all functional groups, including forage fish (12%), with the exception of sea turtles. A modeled increase in forage fish consumption rate by 50% resulted in a decrease in large jellyfish productivity (29%). A simulated increase of 40% in forage fish harvest enhanced jellyfish productivity (24%), while closure of all fisheries caused a decline in large jellyfish productivity (26%) and productivity increases in upper level consumers. These outcomes not only suggest that jellyfish blooms and fisheries have important effects on the structure of the NHCS, but they also support the hypothesis that forage fishing provides a competitive release for large jellyfish. We recommend including jellyfish as a functional group in future ecosystem modeling efforts, including ecosystem-based approaches to fishery management of coastal ecosystems worldwide.

Physiologic effects of ergot alkaloids: What happens when excretion does not equal absorption?

USDA-ARS?s Scientific Manuscript database

Increased persistence of tall fescue (Lolium arundinaceum) infested with an endophytic fungus Epichloë coenophiala (formerly Neotyphodium coenophialum) in forage-based agriculture has led to increased effort in understanding the negative effects caused by consumption of ergot alkaloids by animals co...

Physiologic effects of ergot alkaloids: What happens when excretion does not equal consumption?

USDA-ARS?s Scientific Manuscript database

Increased persistence of tall fescue (Lolium arundinaceum) infested with an endophytic fungus Epichloë coenophiala (formerly Neotyphodium coenophialum) in forage-based agriculture has led to increased effort in understanding the negative effects caused by consumption of ergot alkaloids by animals co...

Meeting reproductive demands in a dynamic upwelling system: foraging strategies of a pursuit-diving seabird, the marbled murrelet

Treesearch

M. Zachariah Peery; Scott H. Newman; Curt D. Storlazzi; Steven R. Beissinger

2009-01-01

Seabirds maintain plasticity in their foraging behavior to cope with energy demands and foraging constraints that vary over the reproductive cycle, but behavioral studies comparing breeding and nonbreeding individuals are rare. Here we characterize how Marbled Murrelets (Brachyramphus marmoratus) adjust their foraging effort in response to changes...

Early life adversity increases foraging and information gathering in European starlings, Sturnus vulgaris

PubMed Central

Andrews, Clare; Viviani, Jérémie; Egan, Emily; Bedford, Thomas; Brilot, Ben; Nettle, Daniel; Bateson, Melissa

2015-01-01

Animals can insure themselves against the risk of starvation associated with unpredictable food availability by storing energy reserves or gathering information about alternative food sources. The former strategy carries costs in terms of mass-dependent predation risk, while the latter trades off against foraging for food; both trade-offs may be influenced by an individual's developmental history. Here, we consider a possible role of early developmental experience in inducing different mass regulation and foraging strategies in European starlings. We measured the body mass, body condition, foraging effort, food consumption and contrafreeloading (foraging for food hidden in sand when equivalent food is freely available) of adult birds (≥10 months old) that had previously undergone a subtle early life manipulation of food competition (cross-fostering into the highest or lowest ranks in the brood size hierarchy when 2–12 days of age). We found that developmentally disadvantaged birds were fatter in adulthood and differed in foraging behaviour compared with their advantaged siblings. Disadvantaged birds were hyperphagic compared with advantaged birds, but only following a period of food deprivation, and also spent more time contrafreeloading. Advantaged birds experienced a trade-off between foraging success and time spent contrafreeloading, whereas disadvantaged birds faced no such trade-off, owing to their greater foraging efficiency. Thus, developmentally disadvantaged birds appeared to retain a phenotypic memory of increased nestling food competition, employing both energy storage and information-gathering insurance strategies to a greater extent than their advantaged siblings. Our results suggest that subtle early life disadvantage in the form of psychosocial stress and/or food insecurity can leave a lasting legacy on foraging behaviour and mass regulation even in the absence of food insufficiency during development or adulthood. PMID:26566292

Evaluating Energy Flows Through Jellyfish and Forage Fish and the Effects of Fishing on the Northern Humboldt Current Ecosystem

NASA Astrophysics Data System (ADS)

Chiaverano, L.; Robinson, K. L.; Ruzicka, J.; Quiñones, J.; Tam, J.; Acha, M.; Graham, W. M.; Brodeur, R.; Decker, M. B.; Hernandez, F., Jr.; Leaf, R.; Mianzan, H.; Uye, S. I.

2016-02-01

Increases in the frequency of jellyfish mass occurrences in a number of coastal areas around the globe have intensified concerns that some ecosystems are becoming "jellyfish-dominated". Gelatinous planktivores not only compete with forage fish for food, but also feed on fish eggs and larvae. When jellyfish abundance is high, the fraction of the energy and the efficiency at which it is transferred upwards in the food web are reduced compared with times when fish are dominant. Hence, ecosystems supporting major forage fish fisheries are the most likely to experience fish-to-jellyfish shifts due to the harvest pressure on mid-trophic planktivores. Although forage fish-jellyfish replacement cycles have been detected in recent decades in some productive, coastal ecosystems (e.g. Gulf of Mexico, Northern California Current), jellyfish are typically not included in ecosystem-based fisheries management (EBFM) production models. Here we explored the roles of jellyfish and forage fish as trophic energy transfer pathways to higher trophic levels in the Northern Humboldt Current (NHC) ecosystem, one of the most productive ecosystems in the world. A trophic network model with 33 functional groups was developed using ECOPATH and transformed to an end-to-end model using ECOTRAN techniques to map food web energy flows. Predicted, relative changes in functional group productivity were analyzed in simulations with varying forage fish consumption rates, jellyfish consumption rates, and forage fish harvest rates in a suite of static, alternative-energy-demand scenarios. Our modeling efforts will not only improve EBFM of forage fish and their predators in the NHC ecosystem, but also increase our understanding of trophic interactions between forage fish and large jellyfish, an important, but overlooked component in most ecosystem models to date.

Do Behavioral Foraging Responses of Prey to Predators Function Similarly in Restored and Pristine Foodwebs?

PubMed Central

Madin, Elizabeth M. P.; Gaines, Steven D.; Madin, Joshua S.; Link, Anne-Katrin; Lubchenco, Peggy J.; Selden, Rebecca L.; Warner, Robert R.

2012-01-01

Efforts to restore top predators in human-altered systems raise the question of whether rebounds in predator populations are sufficient to restore pristine foodweb dynamics. Ocean ecosystems provide an ideal system to test this question. Removal of fishing in marine reserves often reverses declines in predator densities and size. However, whether this leads to restoration of key functional characteristics of foodwebs, especially prey foraging behavior, is unclear. The question of whether restored and pristine foodwebs function similarly is nonetheless critically important for management and restoration efforts. We explored this question in light of one important determinant of ecosystem function and structure – herbivorous prey foraging behavior. We compared these responses for two functionally distinct herbivorous prey fishes (the damselfish Plectroglyphidodon dickii and the parrotfish Chlorurus sordidus) within pairs of coral reefs in pristine and restored ecosystems in two regions of these species' biogeographic ranges, allowing us to quantify the magnitude and temporal scale of this key ecosystem variable's recovery. We demonstrate that restoration of top predator abundances also restored prey foraging excursion behaviors to a condition closely resembling those of a pristine ecosystem. Increased understanding of behavioral aspects of ecosystem change will greatly improve our ability to predict the cascading consequences of conservation tools aimed at ecological restoration, such as marine reserves. PMID:22403650

Effect of reducing dietary forage in lower starch diets on performance, ruminal characteristics, and nutrient digestibility in lactating Holstein cows.

PubMed

Farmer, E R; Tucker, H A; Dann, H M; Cotanch, K W; Mooney, C S; Lock, A L; Yagi, K; Grant, R J

2014-09-01

This experiment evaluated the effect of feeding a lower starch diet (21% of dry matter) with different amounts of forage (52, 47, 43, and 39% of dry matter) on lactational performance, chewing activity, ruminal fermentation and turnover, microbial N yield, and total-tract nutrient digestibility. Dietary forage consisted of a mixture of corn and haycrop silages, and as dietary forage content was reduced, chopped wheat straw (0-10% of dry matter) was added in an effort to maintain chewing activity. Dietary concentrate was adjusted (corn meal, nonforage fiber sources, and protein sources) to maintain similar amounts of starch and other carbohydrate and protein fractions among the diets. Sixteen lactating Holstein cows were used in replicated 4×4 Latin squares with 21-d periods. Dry matter intake increased while physically effective neutral detergent fiber (peNDF1.18) intake was reduced as forage content decreased from 52 to 39%. However, reducing dietary forage did not influence milk yield or composition, although we observed changes in dry matter intake. Time spent chewing, eating, and ruminating (expressed as minutes per day or as minutes per kilogram of NDF intake) were not affected by reducing dietary forage. However, addition of chopped wheat straw to the diets resulted in greater time spent chewing and eating per kilogram of peNDF1.18 consumed. Reducing dietary forage from 52 to 39% did not affect ruminal pH, ruminal digesta volume and mass, ruminal pool size of NDF or starch, ruminal digesta mat consistency, or microbial N yield. Ruminal acetate-to-propionate ratio was reduced, ruminal turnover rates of NDF and starch were greater, and total-tract digestibility of fiber diminished as dietary forage content decreased. Reducing the dietary forage content from 52 to 39% of dry matter, while increasing wheat straw inclusion to maintain chewing and rumen function, resulted in similar milk yield and composition although feed intake increased. With the lower starch diets in this short-term study, the minimal forage content to maintain lactational performance was between 39 and 43%. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Mean Annual Temperature Drives Microbial Nitrogen Cycling and Fine Root Nutrient Foraging Across a Tropical Montane Wet Forest Elevation Gradient

NASA Astrophysics Data System (ADS)

Pierre, S.; Litton, C. L. M.; Giardina, C. P.; Sparks, J. P.; Groffman, P. M.; Hewson, I.; Fahey, T. J.

2017-12-01

Mean annual temperature (MAT) is positively correlated with rates of primary production and carbon (C) turnover in forests globally, but the underlying biotic drivers of these relationships remain poorly resolved. We hypothesized that (1) MAT increases nitrifier abundance and thereby nitrate (NO-) bioavailability in soils and (2) increased NO- bioavailability reduces fine root nitrogen (N) demand. We used an ecologically well-constrained natural elevation gradient (13˚C -18˚C) in a tropical wet motane forest on the Island of Hawaii to study to role of MAT in situ. Our previous work showed that MAT drives increased soil NO- bioavailability in situ (r²=0.79, P=0.003), and indicated that the abundance of ammonia oxidizing archaea is strongly and positively correlated with MAT in situ (r²=0.34, P<0.001; Pierre et. al. 2017). Using fertilized fine root ingrowth cores (+N, +P, +N+P, control) across the same MAT gradient, we found that increasing MAT and bulk soil NO- bioavailability produced a significant negative fine root response to the +N+P treatment (P=0.023), and no response to other fertilization treatments. Increasing MAT and soil NO- bioavailability led to increased percent arbuscular mycorrhizal (AM) colonization of fine roots (r²=0.43, P=0.004), but no treatment effect on AM colonization was observed. Our results suggest that N and P generally co-limit fine root foraging across the gradient, while higher MAT and bulk soil NO- bioavailability interact to reduce fine root foraging effort. Further, higher MAT and greater N fertility in soils may reduce the C limitation of AM fungal colonization. We conclude that MAT drives N-rich conditions, which allow for lower N foraging effort, but greater C investment in P acquisition through AM fine root colonization.

Late-instar Behavior of Aedes aegypti (Diptera: Culicidae) Larvae in Different Thermal and Nutritive Environments.

PubMed

Reiskind, Michael H; Janairo, M Shawn

2015-09-01

The effects of temperature on ectotherm growth have been well documented. How temperature affects foraging behavior is less well explored, and has not been studied in larval mosquitoes. We hypothesized that temperature changes foraging behavior in the aquatic larval phase of the mosquito, Aedes aegypti L. Based on empirical results in other systems, we predicted that foraging effort would increase at higher temperatures in these insects. We tested this prediction over three temperature conditions at two food levels. We measured behaviors by video recording replicated cohorts of fourth-instar mosquitoes and assessing individual behavior and time budgets using an ethogram. We found both food level and temperature had significant impacts on larval foraging behavior, with more time spent actively foraging at low food levels and at low temperatures, and more occurrences of active foraging at both temperature extremes. These results are contrary to some of our predictions, but fit into theoretical responses to temperature based upon dynamic energy budget models. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A negative feedback signal that is triggered by peril curbs honey bee recruitment.

PubMed

Nieh, James C

2010-02-23

Decision making in superorganisms such as honey bee colonies often uses self-organizing behaviors, feedback loops that allow the colony to gather information from multiple individuals and achieve reliable and agile solutions. Honey bees use positive feedback from the waggle dance to allocate colony foraging effort. However, the use of negative feedback signals by superorganisms is poorly understood. I show that conspecific attacks at a food source lead to the production of stop signals, communication that was known to reduce waggle dancing and recruitment but lacked a clear natural trigger. Signalers preferentially targeted nestmates visiting the same food source, on the basis of its odor. During aggressive food competition, attack victims increased signal production by 43 fold. Foragers that attacked competitors or experienced no aggression did not alter signal production. Biting ambush predators also attack foragers at flowers. Simulated biting of foragers or exposure to bee alarm pheromone also elicited signaling (88-fold and 14-fold increases, respectively). This provides the first clear evidence of a negative feedback signal elicited by foraging peril to counteract the positive feedback of the waggle dance. As in intra- and intercellular communication, negative feedback may play an important, though currently underappreciated, role in self-organizing behaviors within superorganisms. Copyright 2010 Elsevier Ltd. All rights reserved.

Yellowjackets use nest-based cues to differentially exploit higher-quality resources

NASA Astrophysics Data System (ADS)

Taylor, Benjamin J.; Schalk, Dane R.; Jeanne, Robert L.

2010-12-01

While foraging, social insects encounter a dynamic array of food resources of varying quality and profitability. Because food acquisition influences colony growth and fitness, natural selection can be expected to favor colonies that allocate their overall foraging effort so as to maximize their intake of high-quality nutrients. Social wasps lack recruitment communication, but previous studies of vespine wasps have shown that olfactory cues influence foraging decisions. Odors associated with food brought into the nest by successful foragers prompt naive foragers to leave the nest and search for the source of those odors. Left unanswered, however, is the question of whether naive foragers take food quality into account in making their decisions about whether or not to search. In this study, two different concentrations of sucrose solutions, scented differently, were inserted directly into each of three Vespula germanica nests. At a feeder away from the nest, arriving foragers were given a choice between two 1.5 M sucrose solutions with the same scents as those in the nest. We show that wasps chose higher-quality resources in the field using information in the form of intranidal food-associated odor cues. By this simple mechanism, the colony can bias the allocation of its foraging effort toward higher-quality resources in the environment.

Shearwater Foraging in the Southern Ocean: The Roles of Prey Availability and Winds

PubMed Central

Raymond, Ben; Shaffer, Scott A.; Sokolov, Serguei; Woehler, Eric J.; Costa, Daniel P.; Einoder, Luke; Hindell, Mark; Hosie, Graham; Pinkerton, Matt; Sagar, Paul M.; Scott, Darren; Smith, Adam; Thompson, David R.; Vertigan, Caitlin; Weimerskirch, Henri

2010-01-01

Background Sooty (Puffinus griseus) and short-tailed (P. tenuirostris) shearwaters are abundant seabirds that range widely across global oceans. Understanding the foraging ecology of these species in the Southern Ocean is important for monitoring and ecosystem conservation and management. Methodology/Principal Findings Tracking data from sooty and short-tailed shearwaters from three regions of New Zealand and Australia were combined with at-sea observations of shearwaters in the Southern Ocean, physical oceanography, near-surface copepod distributions, pelagic trawl data, and synoptic near-surface winds. Shearwaters from all three regions foraged in the Polar Front zone, and showed particular overlap in the region around 140°E. Short-tailed shearwaters from South Australia also foraged in Antarctic waters south of the Polar Front. The spatial distribution of shearwater foraging effort in the Polar Front zone was matched by patterns in large-scale upwelling, primary production, and abundances of copepods and myctophid fish. Oceanic winds were found to be broad determinants of foraging distribution, and of the flight paths taken by the birds on long foraging trips to Antarctic waters. Conclusions/Significance The shearwaters displayed foraging site fidelity and overlap of foraging habitat between species and populations that may enhance their utility as indicators of Southern Ocean ecosystems. The results highlight the importance of upwellings due to interactions of the Antarctic Circumpolar Current with large-scale bottom topography, and the corresponding localised increases in the productivity of the Polar Front ecosystem. PMID:20532034

Physiological effects of increased foraging effort in a small passerine.

PubMed

Yap, Kang Nian; Kim, Oh Run; Harris, Karilyn C; Williams, Tony D

2017-11-15

Foraging to obtain food, either for self-maintenance or at presumably elevated rates to provide for offspring, is thought to be an energetically demanding activity but one that is essential for fitness (higher reproductive success and survival). Nevertheless, the physiological mechanisms that allow some individuals to support higher foraging performance, and the mechanisms underlying costs of high workload, remain poorly understood. We experimentally manipulated foraging behaviour in zebra finches ( Taeniopygia guttata ) using the technique described by Koetsier and Verhulst (2011) Birds in the 'high foraging effort' (HF) group had to obtain food either while flying/hovering or by making repeated hops or jumps from the ground up to the feeder, behaviour typical of the extremely energetically expensive foraging mode observed in many free-living small passerines. HF birds made significantly more trips to the feeder per 10 min, whereas control birds spent more time (perched) at the feeder. Despite this marked change in foraging behaviour, we documented few short- or long-term effects of 'training' (3 days and 90 days of 'training', respectively) and some of these effects were sex specific. There were no effects of treatment on basal metabolic rate, haematocrit, haemoglobin or plasma glycerol, triglyceride and glucose levels, and masses of kidney, crop, large intestine, small intestine, gizzard and liver. HF females had higher masses of flight muscle, leg muscle, heart and lung compared with controls. In contrast, HF males had lower heart mass than controls and there were no differences for other organs. When both sexes were pooled, there were no effects of treatment on body composition. Finally, birds in the HF treatment group had higher levels of reactive oxygen metabolites (dROMs) and, consequently, although treatment did not affect total anti-oxidant capacity, birds in the HF treatment group had higher oxidative stress. © 2017. Published by The Company of Biologists Ltd.

ASAS Centennial Paper: Future needs of research and extension in forage utilization.

PubMed

Rouquette, F M; Redmon, L A; Aiken, G E; Hill, G M; Sollenberger, L E; Andrae, J

2009-01-01

Forage-animal production agriculture is implementing infrastructure changes and management strategies to adjust to increased energy-related costs of fuel, feed grains, fertilizers, and seeds. The primary objectives of this position paper are to assess future research and extension scientific needs in forage utilization, financial support for the discipline, and changing status and number of scientists. A survey questionnaire returned from 25 land-grant universities in the eastern half of the United States rated the top 4 research needs as 1) pasture systems and efficiency of production; 2) interfacing with energy concerns; 3) forage cultivar evaluations and persistence; and 4) environment impacts. Plant-animal future research needs at 11 USDA-ARS regional locations are targeted at sustainable management and improved livestock performance, ecophysiology and ecology of grasslands, environment impacts, and improved technologies for nutritive value assessments. Extension scientists from 17 southern and northeastern states listed the top 3 needs as forage persistence, soil fertility and nutrient management, and pasture systems and efficiency of production. Grant funds currently provide more than 40% of land-grant university research and extension efforts in forage utilization, and scientists estimate that this support base will increase to 55 to 60% of the funding total by 2013. Reduced allocation of state and federal funding has contributed to a reduction in the number of full-time equivalent (FTE) scientists engaged in forage utilization research and extension activities. The current 25 state FTE conducting research number about 2.8 per state. This includes 10 states with >3, 11 states with <2, and 3 states with <1 FTE. Increased interest in cellulosic energy, climate change, and environmental impact may offer new opportunities for these FTE to participate in integrated cross-discipline research Extension programming, and technology transfer methods will change to accommodate reduced funding but with increasing numbers of novice, recreation-oriented landowners.

Planning pastures: taking species attributes to the landscape

USDA-ARS?s Scientific Manuscript database

Winter hardiness limits the use of the productive forage grass perennial ryegrass (Lolium perenne L.) in the northeastern United States. Both efforts to breed more cold-tolerant varieties and the changing climate increase the potential of this grass in pastures. Growth chamber studies of thirteen co...

Pronounced Seasonal Changes in the Movement Ecology of a Highly Gregarious Central-Place Forager, the African Straw-Coloured Fruit Bat (Eidolon helvum)

PubMed Central

Fahr, Jakob; Abedi-Lartey, Michael; Esch, Thomas; Machwitz, Miriam; Suu-Ire, Richard; Wikelski, Martin; Dechmann, Dina K. N.

2015-01-01

Background Straw-coloured fruit bats (Eidolon helvum) migrate over vast distances across the African continent, probably following seasonal bursts of resource availability. This causes enormous fluctuations in population size, which in turn may influence the bats’ impact on local ecosystems. We studied the movement ecology of this central-place forager with state-of-the-art GPS/acceleration loggers and concurrently monitored the seasonal fluctuation of the colony in Accra, Ghana. Habitat use on the landscape scale was assessed with remote sensing data as well as ground-truthing of foraging areas. Principal Findings During the wet season population low (~ 4000 individuals), bats foraged locally (3.5–36.7 km) in urban areas with low tree cover. Major food sources during this period were fruits of introduced trees. Foraging distances almost tripled (24.1–87.9 km) during the dry season population peak (~ 150,000 individuals), but this was not compensated for by reduced resting periods. Dry season foraging areas were random with regard to urban footprint and tree cover, and food consisted almost exclusively of nectar and pollen of native trees. Conclusions and Significance Our study suggests that straw-coloured fruit bats disperse seeds in the range of hundreds of meters up to dozens of kilometres, and pollinate trees for up to 88 km. Straw-coloured fruit bats forage over much larger distances compared to most other Old World fruit bats, thus providing vital ecosystem services across extensive landscapes. We recommend increased efforts aimed at maintaining E. helvum populations throughout Africa since their keystone role in various ecosystems is likely to increase due to the escalating loss of other seed dispersers as well as continued urbanization and habitat fragmentation. PMID:26465139

Pronounced Seasonal Changes in the Movement Ecology of a Highly Gregarious Central-Place Forager, the African Straw-Coloured Fruit Bat (Eidolon helvum).

PubMed

Fahr, Jakob; Abedi-Lartey, Michael; Esch, Thomas; Machwitz, Miriam; Suu-Ire, Richard; Wikelski, Martin; Dechmann, Dina K N

2015-01-01

Straw-coloured fruit bats (Eidolon helvum) migrate over vast distances across the African continent, probably following seasonal bursts of resource availability. This causes enormous fluctuations in population size, which in turn may influence the bats' impact on local ecosystems. We studied the movement ecology of this central-place forager with state-of-the-art GPS/acceleration loggers and concurrently monitored the seasonal fluctuation of the colony in Accra, Ghana. Habitat use on the landscape scale was assessed with remote sensing data as well as ground-truthing of foraging areas. During the wet season population low (~ 4000 individuals), bats foraged locally (3.5-36.7 km) in urban areas with low tree cover. Major food sources during this period were fruits of introduced trees. Foraging distances almost tripled (24.1-87.9 km) during the dry season population peak (~ 150,000 individuals), but this was not compensated for by reduced resting periods. Dry season foraging areas were random with regard to urban footprint and tree cover, and food consisted almost exclusively of nectar and pollen of native trees. Our study suggests that straw-coloured fruit bats disperse seeds in the range of hundreds of meters up to dozens of kilometres, and pollinate trees for up to 88 km. Straw-coloured fruit bats forage over much larger distances compared to most other Old World fruit bats, thus providing vital ecosystem services across extensive landscapes. We recommend increased efforts aimed at maintaining E. helvum populations throughout Africa since their keystone role in various ecosystems is likely to increase due to the escalating loss of other seed dispersers as well as continued urbanization and habitat fragmentation.

Sperm whales reduce foraging effort during exposure to 1-2 kHz sonar and killer whale sounds.

PubMed

Isojunno, Saana; Cure, Charlotte; Kvadsheim, Petter Helgevold; Lam, Frans-Peter Alexander; Tyack, Peter Lloyd; Wensveen, Paul Jacobus; Miller, Patrick James O'Malley

2016-01-01

The time and energetic costs of behavioral responses to incidental and experimental sonar exposures, as well as control stimuli, were quantified using hidden state analysis of time series of acoustic and movement data recorded by tags (DTAG) attached to 12 sperm whales (Physeter macrocephalus) using suction cups. Behavioral state transition modeling showed that tagged whales switched to a non-foraging, non-resting state during both experimental transmissions of low-frequency active sonar from an approaching vessel (LFAS; 1-2 kHz, source level 214 dB re 1 µPa m, four tag records) and playbacks of potential predator (killer whale, Orcinus orca) sounds broadcast at naturally occurring sound levels as a positive control from a drifting boat (five tag records). Time spent in foraging states and the probability of prey capture attempts were reduced during these two types of exposures with little change in overall locomotion activity, suggesting an effect on energy intake with no immediate compensation. Whales switched to the active non-foraging state over received sound pressure levels of 131-165 dB re 1 µPa during LFAS exposure. In contrast, no changes in foraging behavior were detected in response to experimental negative controls (no-sonar ship approach or noise control playback) or to experimental medium-frequency active sonar exposures (MFAS; 6-7 kHz, source level 199 re 1 µPa m, received sound pressure level [SPL] = 73-158 dB re 1 µPa). Similarly, there was no reduction in foraging effort for three whales exposed to incidental, unidentified 4.7-5.1 kHz sonar signals received at lower levels (SPL = 89-133 dB re 1 µPa). These results demonstrate that similar to predation risk, exposure to sonar can affect functional behaviors, and indicate that increased perception of risk with higher source level or lower frequency may modulate how sperm whales respond to anthropogenic sound.

Maintaining social cohesion is a more important determinant of patch residence time than maximizing food intake rate in a group-living primate, Japanese macaque (Macaca fuscata).

PubMed

Kazahari, Nobuko

2014-04-01

Animals have been assumed to employ an optimal foraging strategy (e.g., rate-maximizing strategy). In patchy food environments, intake rate within patches is positively correlated with patch quality, and declines as patches are depleted through consumption. This causes patch-leaving and determines patch residence time. In group-foraging situations, patch residence times are also affected by patch sharing. Optimal patch models for groups predict that patch residence times decrease as the number of co-feeding animals increases because of accelerated patch depletion. However, group members often depart patches without patch depletion, and their patch residence time deviates from patch models. It has been pointed out that patch residence time is also influenced by maintaining social proximity with others among group-living animals. In this study, the effects of maintaining social cohesion and that of rate-maximizing strategy on patch residence time were examined in Japanese macaques (Macaca fuscata). I hypothesized that foragers give up patches to remain in the proximity of their troop members. On the other hand, foragers may stay for a relatively long period when they do not have to abandon patches to follow the troop. In this study, intake rate and foraging effort (i.e., movement) did not change during patch residency. Macaques maintained their intake rate with only a little foraging effort. Therefore, the patches were assumed to be undepleted during patch residency. Further, patch residence time was affected by patch-leaving to maintain social proximity, but not by the intake rate. Macaques tended to stay in patches for short periods when they needed to give up patches for social proximity, and remained for long periods when they did not need to leave to keep social proximity. Patch-leaving and patch residence time that prioritize the maintenance of social cohesion may be a behavioral pattern in group-living primates.

Trade-offs between energy maximization and parental care in a central place forager, the sea otter

USGS Publications Warehouse

Thometz, N M; Staedler, M.M.; Tomoleoni, Joseph; Bodkin, James L.; Bentall, G.B.; Tinker, M. Tim

2016-01-01

Between 1999 and 2014, 126 archival time–depth recorders (TDRs) were used to examine the foraging behavior of southern sea otters (Enhydra lutris nereis) off the coast of California, in both resource-abundant (recently occupied, low sea otter density) and resource-limited (long-occupied, high sea otter density) locations. Following predictions of foraging theory, sea otters generally behaved as energy rate maximizers. Males and females without pups employed similar foraging strategies to optimize rates of energy intake in resource-limited habitats, with some exceptions. Both groups increased overall foraging effort and made deeper, longer and more energetically costly dives as resources became limited, but males were more likely than females without pups to utilize extreme dive profiles. In contrast, females caring for young pups (≤10 weeks) prioritized parental care over energy optimization. The relative importance of parental care versus energy optimization for adult females with pups appeared to reflect developmental changes as dependent young matured. Indeed, contrary to females during the initial stages of lactation, females with large pups approaching weaning once again prioritized optimizing energy intake. The increasing prioritization of energy optimization over the course of lactation was possible due to the physiological development of pups and likely driven by the energetic deficit incurred by females early in lactation. Our results suggest that regardless of resource availability, females at the end of lactation approach a species-specific ceiling for percent time foraging and that reproductive females in the central portion of the current southern sea otter range are disproportionately affected by resource limitation.

Time limits during visual foraging reveal flexible working memory templates.

PubMed

Kristjánsson, Tómas; Thornton, Ian M; Kristjánsson, Árni

2018-06-01

During difficult foraging tasks, humans rarely switch between target categories, but switch frequently during easier foraging. Does this reflect fundamental limits on visual working memory (VWM) capacity or simply strategic choice due to effort? Our participants performed time-limited or unlimited foraging tasks where they tapped stimuli from 2 target categories while avoiding items from 2 distractor categories. These time limits should have no effect if capacity imposes limits on VWM representations but more flexible VWM could allow observers to use VWM according to task demands in each case. We found that with time limits, participants switched more frequently and switch-costs became much smaller than during unlimited foraging. Observers can therefore switch between complex (conjunction) target categories when needed. We propose that while maintaining many complex templates in working memory is effortful and observers avoid this, they can do so if this fits task demands, showing the flexibility of working memory representations used for visual exploration. This is in contrast with recent proposals, and we discuss the implications of these findings for theoretical accounts of working memory. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Recruitment-dance signals draw larger audiences when honey bee colonies have multiple patrilines

PubMed Central

Mattila, H. R.; Seeley, T. D.

2010-01-01

Honey bee queens (Apis mellifera) who mate with multiple males produce colonies that are filled with numerous genetically distinct patrilines of workers. A genetically diverse colony benefits from an enhanced foraging effort, fuelled in part by an increase in the number of recruitment signals that are produced by foragers. However, the influence of patriline diversity on the attention paid to these signals by audiences of potentially receptive workers remains unexplored. To determine whether recruitment dances performed by foragers in multiple-patriline colonies attract a greater number of dance followers than dances in colonies that lack patriline diversity, we trained workers from multiple- and single-patriline colonies to forage in a greenhouse and monitored their dance-following activity back in the hives. On average, more workers followed a dance if it was performed in a multiple-patriline colony rather than a single-patriline colony (33% increase), and for a greater number of dance circuits per follower. Furthermore, dance-following workers in multiple-patriline colonies were more likely to exit their hive after following a dance, although this did not translate to a difference in colony-level exit rates between treatment types. Recruiting nest mates to profitable food sources through dance communication is critical to a colony’s foraging success and long-term fitness; polyandrous queens produce colonies that benefit not only from increased recruitment signalling, but also from the generation of larger and more attentive audiences of signal receivers. This study highlights the importance of integrating responses of both signal senders and receivers to understand more fully the success of animal-communication systems. PMID:21350596

Recruitment-dance signals draw larger audiences when honey bee colonies have multiple patrilines.

PubMed

Girard, M B; Mattila, H R; Seeley, T D

2011-02-01

Honey bee queens (Apis mellifera) who mate with multiple males produce colonies that are filled with numerous genetically distinct patrilines of workers. A genetically diverse colony benefits from an enhanced foraging effort, fuelled in part by an increase in the number of recruitment signals that are produced by foragers. However, the influence of patriline diversity on the attention paid to these signals by audiences of potentially receptive workers remains unexplored. To determine whether recruitment dances performed by foragers in multiple-patriline colonies attract a greater number of dance followers than dances in colonies that lack patriline diversity, we trained workers from multiple- and single-patriline colonies to forage in a greenhouse and monitored their dance-following activity back in the hives. On average, more workers followed a dance if it was performed in a multiple-patriline colony rather than a single-patriline colony (33% increase), and for a greater number of dance circuits per follower. Furthermore, dance-following workers in multiple-patriline colonies were more likely to exit their hive after following a dance, although this did not translate to a difference in colony-level exit rates between treatment types. Recruiting nest mates to profitable food sources through dance communication is critical to a colony's foraging success and long-term fitness; polyandrous queens produce colonies that benefit not only from increased recruitment signalling, but also from the generation of larger and more attentive audiences of signal receivers. This study highlights the importance of integrating responses of both signal senders and receivers to understand more fully the success of animal-communication systems.

Social effects on foraging behavior and success depend on local environmental conditions

PubMed Central

Marshall, Harry H; Carter, Alecia J; Ashford, Alexandra; Rowcliffe, J Marcus; Cowlishaw, Guy

2015-01-01

In social groups, individuals' dominance rank, social bonds, and kinship with other group members have been shown to influence their foraging behavior. However, there is growing evidence that the particular effects of these social traits may also depend on local environmental conditions. We investigated this by comparing the foraging behavior of wild chacma baboons, Papio ursinus, under natural conditions and in a field experiment where food was spatially clumped. Data were collected from 55 animals across two troops over a 5-month period, including over 900 agonistic foraging interactions and over 600 food patch visits in each condition. In both conditions, low-ranked individuals received more agonism, but this only translated into reduced foraging performances for low-ranked individuals in the high-competition experimental conditions. Our results suggest one possible reason for this pattern may be low-ranked individuals strategically investing social effort to negotiate foraging tolerance, but the rank-offsetting effect of this investment being overwhelmed in the higher-competition experimental environment. Our results also suggest that individuals may use imbalances in their social bonds to negotiate tolerance from others under a wider range of environmental conditions, but utilize the overall strength of their social bonds in more extreme environments where feeding competition is more intense. These findings highlight that behavioral tactics such as the strategic investment of social effort may allow foragers to mitigate the costs of low rank, but that the effectiveness of these tactics is likely to be limited in certain environments. PMID:25691973

Restoration through eradication? Removal of an invasive bioengineer restores some habitat function for a native predator.

PubMed

Holsman, Kirstin K; McDonald, P Sean; Barreyro, Pablo A; Armstrong, David A

2010-12-01

Invasive aquatic macrophytes increase structural complexity in recipient systems and alter trophic and physical resources; thus, eradication programs that remove plant structure have potential to restore some impaired ecological functions. In this study we evaluate how an invasive ecosystem engineer, Atlantic smooth cordgrass (Spartina alterniflora), interferes with the movement and foraging activity of a mobile predator, Dungeness crab (Cancer magister), and whether removal of aboveground cordgrass structure rapidly reestablishes access to foraging habitats. By 2004, smooth cordgrass had invaded >25% of crab foraging habitat in Willapa Bay, Washington (USA), and transformed it into a highly structured landscape. However, by 2007 successful eradication efforts had eliminated most meadows of the cordgrass. In order to investigate the effect of smooth cordgrass on the habitat function of littoral areas for foraging crabs, we integrated field, laboratory, and statistical modeling approaches. We conducted trapping surveys at multiple sites and used a hierarchical model framework to examine patterns in catches prior to and following cordgrass removal (i.e., before-after control-impact design, BACI). Prior to eradication, catches of Dungeness crabs in unstructured habitats were 4-19 times higher than catches in adjacent patches of live cordgrass. In contrast, the results of post-eradication trapping in 2007 indicated similar catch rates of crabs in unstructured habitats and areas formerly invaded by the cordgrass. Subsequent laboratory experiments and video observations demonstrated that the rigid physical structure of smooth cordgrass shoots reduces the ability of Dungeness crabs to access prey resources and increases the risk of stranding. Taken together, these findings suggest that eliminating the structural complexity of invasive macrophytes may rapidly restore some ecological function (i.e., foraging area) for migratory predators like Dungeness crab. However, restoration of affected areas to a preinvasion state will also depend on long-term patterns of succession in invaded areas and the degree of persistence of physical changes that continue to alter biotic characteristics of the habitat. Our work highlights: (1) the efficacy of employing multiple methods of inquiry to evaluate causal relationships through mechanisms of interaction, and (2) the importance of targeting particular ecological functions when identifying both short- and long-term goals of restoration efforts.

Foraging behaviour of juvenile female New Zealand sea lions (Phocarctos hookeri) in contrasting environments.

PubMed

Leung, Elaine S; Augé, Amélie A; Chilvers, B Louise; Moore, Antoni B; Robertson, Bruce C

2013-01-01

Foragers can show adaptive responses to changes within their environment through morphological and behavioural plasticity. We investigated the plasticity in body size, at sea movements and diving behaviour of juvenile female New Zealand (NZ) sea lions (Phocarctos hookeri) in two contrasting environments. The NZ sea lion is one of the rarest pinnipeds in the world. Most of the species is based at the subantarctic Auckland Islands (AI; considered to be marginal foraging habitat), with a recolonizing population on the Otago Peninsula, NZ mainland (considered to be more optimal habitat). We investigated how juvenile NZ sea lions adjust their foraging behaviour in contrasting environments by deploying satellite-linked platform transmitting terminals (PTTs) and time-depth recorders (TDRs) on 2-3 year-old females at AI (2007-2010) and Otago (2009-2010). Juvenile female NZ sea lions exhibited plasticity in body size and behaviour. Otago juveniles were significantly heavier than AI juveniles. Linear mixed effects models showed that study site had the most important effect on foraging behaviour, while mass and age had little influence. AI juveniles spent more time at sea, foraged over larger areas, and dove deeper and longer than Otago juveniles. It is difficult to attribute a specific cause to the observed contrasts in foraging behaviour because these differences may be driven by disparities in habitat/prey characteristics, conspecific density levels or interseasonal variation. Nevertheless, the smaller size and increased foraging effort of AI juveniles, combined with the lower productivity in this region, support the hypothesis that AI are less optimal habitat than Otago. It is more difficult for juveniles to forage in suboptimal habitats given their restricted foraging ability and lower tolerance for food limitation compared to adults. Thus, effective management measures should consider the impacts of low resource environments, along with changes that can alter food availability such as potential resource competition with fisheries.

Foraging Behaviour of Juvenile Female New Zealand Sea Lions (Phocarctos hookeri) in Contrasting Environments

PubMed Central

Leung, Elaine S.; Augé, Amélie A.; Chilvers, B. Louise; Moore, Antoni B.; Robertson, Bruce C.

2013-01-01

Foragers can show adaptive responses to changes within their environment through morphological and behavioural plasticity. We investigated the plasticity in body size, at sea movements and diving behaviour of juvenile female New Zealand (NZ) sea lions (Phocarctos hookeri) in two contrasting environments. The NZ sea lion is one of the rarest pinnipeds in the world. Most of the species is based at the subantarctic Auckland Islands (AI; considered to be marginal foraging habitat), with a recolonizing population on the Otago Peninsula, NZ mainland (considered to be more optimal habitat). We investigated how juvenile NZ sea lions adjust their foraging behaviour in contrasting environments by deploying satellite-linked platform transmitting terminals (PTTs) and time-depth recorders (TDRs) on 2–3 year-old females at AI (2007–2010) and Otago (2009–2010). Juvenile female NZ sea lions exhibited plasticity in body size and behaviour. Otago juveniles were significantly heavier than AI juveniles. Linear mixed effects models showed that study site had the most important effect on foraging behaviour, while mass and age had little influence. AI juveniles spent more time at sea, foraged over larger areas, and dove deeper and longer than Otago juveniles. It is difficult to attribute a specific cause to the observed contrasts in foraging behaviour because these differences may be driven by disparities in habitat/prey characteristics, conspecific density levels or interseasonal variation. Nevertheless, the smaller size and increased foraging effort of AI juveniles, combined with the lower productivity in this region, support the hypothesis that AI are less optimal habitat than Otago. It is more difficult for juveniles to forage in suboptimal habitats given their restricted foraging ability and lower tolerance for food limitation compared to adults. Thus, effective management measures should consider the impacts of low resource environments, along with changes that can alter food availability such as potential resource competition with fisheries. PMID:23671630

Environmental Fate and the Effects of Herbicides in Forest, Chaparral, and Range Ecosystems of the Southwest

Treesearch

J.L. Michael; D.G. Neary

1995-01-01

Biological methods, fire, herbicides, and mechanical methods have all been studied in an effort to determine appropriate ways of manipulating arid land vegetation for improvement of wildlife habitat, streamflow and water yield, increasing forage for livestock, and enhancing recreational benefits and scenic diversity. Because water is ultimately essential for all of...

Determination of Foraging Thresholds and Effects of Application on Energetic Carrying Capacity for Waterfowl

PubMed Central

2015-01-01

Energetic carrying capacity of habitats for wildlife is a fundamental concept used to better understand population ecology and prioritize conservation efforts. However, carrying capacity can be difficult to estimate accurately and simplified models often depend on many assumptions and few estimated parameters. We demonstrate the complex nature of parameterizing energetic carrying capacity models and use an experimental approach to describe a necessary parameter, a foraging threshold (i.e., density of food at which animals no longer can efficiently forage and acquire energy), for a guild of migratory birds. We created foraging patches with different fixed prey densities and monitored the numerical and behavioral responses of waterfowl (Anatidae) and depletion of foods during winter. Dabbling ducks (Anatini) fed extensively in plots and all initial densities of supplemented seed were rapidly reduced to 10 kg/ha and other natural seeds and tubers combined to 170 kg/ha, despite different starting densities. However, ducks did not abandon or stop foraging in wetlands when seed reduction ceased approximately two weeks into the winter-long experiment nor did they consistently distribute according to ideal-free predictions during this period. Dabbling duck use of experimental plots was not related to initial seed density, and residual seed and tuber densities varied among plant taxa and wetlands but not plots. Herein, we reached several conclusions: 1) foraging effort and numerical responses of dabbling ducks in winter were likely influenced by factors other than total food densities (e.g., predation risk, opportunity costs, forager condition), 2) foraging thresholds may vary among foraging locations, and 3) the numerical response of dabbling ducks may be an inconsistent predictor of habitat quality relative to seed and tuber density. We describe implications on habitat conservation objectives of using different foraging thresholds in energetic carrying capacity models and suggest scientists reevaluate assumptions of these models used to guide habitat conservation. PMID:25790255

The Trail Less Traveled: Individual Decision-Making and Its Effect on Group Behavior

PubMed Central

Lanan, Michele C.; Dornhaus, Anna; Jones, Emily I.; Waser, Andrew; Bronstein, Judith L.

2012-01-01

Social insect colonies are complex systems in which the interactions of many individuals lead to colony-level collective behaviors such as foraging. However, the emergent properties of collective behaviors may not necessarily be adaptive. Here, we examine symmetry breaking, an emergent pattern exhibited by some social insects that can lead colonies to focus their foraging effort on only one of several available food patches. Symmetry breaking has been reported to occur in several ant species. However, it is not clear whether it arises as an unavoidable epiphenomenon of pheromone recruitment, or whether it is an adaptive behavior that can be controlled through modification of the individual behavior of workers. In this paper, we used a simulation model to test how symmetry breaking is affected by the degree of non-linearity of recruitment, the specific mechanism used by individuals to choose between patches, patch size, and forager number. The model shows that foraging intensity on different trails becomes increasingly asymmetric as the recruitment response of individuals varies from linear to highly non-linear, supporting the predictions of previous work. Surprisingly, we also found that the direction of the relationship between forager number (i.e., colony size) and asymmetry varied depending on the specific details of the decision rule used by individuals. Limiting the size of the resource produced a damping effect on asymmetry, but only at high forager numbers. Variation in the rule used by individual ants to choose trails is a likely mechanism that could cause variation among the foraging behaviors of species, and is a behavior upon which selection could act. PMID:23112880

Foraging responses of black-legged kittiwakes to prolonged food-shortages around colonies on the Bering Sea shelf.

PubMed

Paredes, Rosana; Orben, Rachael A; Suryan, Robert M; Irons, David B; Roby, Daniel D; Harding, Ann M A; Young, Rebecca C; Benoit-Bird, Kelly; Ladd, Carol; Renner, Heather; Heppell, Scott; Phillips, Richard A; Kitaysky, Alexander

2014-01-01

We hypothesized that changes in southeastern Bering Sea foraging conditions for black-legged kittiwakes (Rissa tridactyla) have caused shifts in habitat use with direct implications for population trends. To test this, we compared at-sea distribution, breeding performance, and nutritional stress of kittiwakes in three years (2008-2010) at two sites in the Pribilof Islands, where the population has either declined (St. Paul) or remained stable (St. George). Foraging conditions were assessed from changes in (1) bird diets, (2) the biomass and distribution of juvenile pollock (Theragra chalcogramma) in 2008 and 2009, and (3) eddy kinetic energy (EKE; considered to be a proxy for oceanic prey availability). In years when biomass of juvenile pollock was low and patchily distributed in shelf regions, kittiwake diets included little or no neritic prey and a much higher occurrence of oceanic prey (e.g. myctophids). Birds from both islands foraged on the nearby shelves, or made substantially longer-distance trips overnight to the basin. Here, feeding was more nocturnal and crepuscular than on the shelf, and often occurred near anticyclonic, or inside cyclonic eddies. As expected from colony location, birds from St. Paul used neritic waters more frequently, whereas birds from St. George typically foraged in oceanic waters. Despite these distinctive foraging patterns, there were no significant differences between colonies in chick feeding rates or fledging success. High EKE in 2010 coincided with a 63% increase in use of the basin by birds from St. Paul compared with 2008 when EKE was low. Nonetheless, adult nutritional stress, which was relatively high across years at both colonies, peaked in birds from St. Paul in 2010. Diminishing food resources in nearby shelf habitats may have contributed to kittiwake population declines at St Paul, possibly driven by increased adult mortality or breeding desertion due to high foraging effort and nutritional stress.

How well can we predict forage species occurrence and abundance?

USDA-ARS?s Scientific Manuscript database

As part of a larger effort focused on forage species production and management, we have been developing a statistical modeling approach to predict the probability of species occurrence and the abundance for Orchard Grass over the Northeast region of the United States using two selected statistical m...

Inferring Foraging Areas of Nesting Loggerhead Turtles Using Satellite Telemetry and Stable Isotopes

PubMed Central

Ceriani, Simona A.; Roth, James D.; Evans, Daniel R.; Weishampel, John F.; Ehrhart, Llewellyn M.

2012-01-01

In recent years, the use of intrinsic markers such as stable isotopes to link breeding and foraging grounds of migratory species has increased. Nevertheless, several assumptions still must be tested to interpret isotopic patterns found in the marine realm. We used a combination of satellite telemetry and stable isotope analysis to (i) identify key foraging grounds used by female loggerheads nesting in Florida and (ii) examine the relationship between stable isotope ratios and post-nesting migration destinations. We collected tissue samples for stable isotope analysis from 14 females equipped with satellite tags and an additional 57 untracked nesting females. Telemetry identified three post-nesting migratory pathways and associated non-breeding foraging grounds: (1) a seasonal continental shelf–constrained migratory pattern along the northeast U.S. coastline, (2) a non-breeding residency in southern foraging areas and (3) a residency in the waters adjacent to the breeding area. Isotopic variability in both δ13C and δ15N among individuals allowed identification of three distinct foraging aggregations. We used discriminant function analysis to examine how well δ13C and δ15N predict female post-nesting migration destination. The discriminant analysis classified correctly the foraging ground used for all but one individual and was used to predict putative feeding areas of untracked turtles. We provide the first documentation that the continental shelf of the Mid- and South Atlantic Bights are prime foraging areas for a large number (61%) of adult female loggerheads from the largest loggerhead nesting population in the western hemisphere and the second largest in the world. Our findings offer insights for future management efforts and suggest that this technique can be used to infer foraging strategies and residence areas in lieu of more expensive satellite telemetry, enabling sample sizes that are more representative at the population level. PMID:23028943

Habitat-specific foraging of prothonotary warblers: Deducing habitat quality

USGS Publications Warehouse

Lyons, J.E.

2005-01-01

Foraging behavior often reflects food availability in predictable ways. For example, in habitats where food availability is high, predators should attack prey more often and move more slowly than in habitats where food availability is low. To assess relative food availability and habitat quality, I studied the foraging behavior of breeding Prothonotary Warblers (Protonotaria citrea) in two forest habitat types, cypress-gum swamp forest and coastal-plain levee forest. I quantified foraging behavior with focal animal sampling and continuous recording during foraging bouts. I measured two aspects of foraging behavior: 1) prey attack rate (attacks per minute), using four attack maneuvers (glean, sally, hover, strike), and 2) foraging speed (movements per minute), using three types of movement (hop, short flight [???1 m], long flight [>1 m]). Warblers attacked prey more often in cypress-gum swamp forest than in coastal-plain levee forest. Foraging speed, however, was not different between habitats. I also measured foraging effort (% time spent foraging) and relative frequency of attack maneuvers employed in each habitat; neither of these variables was influenced by forest type. I conclude that Prothonotary Warblers encounter more prey when foraging in cypress-gum swamps than in coastal-plain levee forest, and that greater food availability results in higher density and greater reproductive success for birds breeding in cypress-gum swamp.

Ecological allometries and niche use dynamics across Komodo dragon ontogeny.

PubMed

Purwandana, Deni; Ariefiandy, Achmad; Imansyah, M Jeri; Seno, Aganto; Ciofi, Claudio; Letnic, Mike; Jessop, Tim S

2016-04-01

Ontogenetic allometries in ecological habits and niche use are key responses by which individuals maximize lifetime fitness. Moreover, such allometries have significant implications for how individuals influence population and community dynamics. Here, we examined how body size variation in Komodo dragons (Varanus komodoensis) influenced ecological allometries in their: (1) prey size preference, (2) daily movement rates, (3) home range area, and (4) subsequent niche use across ontogeny. With increased body mass, Komodo dragons increased prey size with a dramatic switch from small (≤10 kg) to large prey (≥50 kg) in lizards heavier than 20 kg. Rates of foraging movement were described by a non-linear concave down response with lizard increasing hourly movement rates up until ∼20 kg body mass before decreasing daily movement suggesting reduced foraging effort in larger lizards. In contrast, home range area exhibited a sigmoid response with increased body mass. Intrapopulation ecological niche use and overlap were also strongly structured by body size. Thus, ontogenetic allometries suggest Komodo dragon's transition from a highly active foraging mode exploiting small prey through to a less active sit and wait feeding strategy focused on killing large ungulates. Further, our results suggest that as body size increases across ontogeny, the Komodo dragon exhibited marked ontogenetic niche shifts that enabled it to function as an entire vertebrate predator guild by exploiting prey across multiple trophic levels.

Ecological allometries and niche use dynamics across Komodo dragon ontogeny

NASA Astrophysics Data System (ADS)

Purwandana, Deni; Ariefiandy, Achmad; Imansyah, M. Jeri; Seno, Aganto; Ciofi, Claudio; Letnic, Mike; Jessop, Tim S.

2016-04-01

Ontogenetic allometries in ecological habits and niche use are key responses by which individuals maximize lifetime fitness. Moreover, such allometries have significant implications for how individuals influence population and community dynamics. Here, we examined how body size variation in Komodo dragons ( Varanus komodoensis) influenced ecological allometries in their: (1) prey size preference, (2) daily movement rates, (3) home range area, and (4) subsequent niche use across ontogeny. With increased body mass, Komodo dragons increased prey size with a dramatic switch from small (≤10 kg) to large prey (≥50 kg) in lizards heavier than 20 kg. Rates of foraging movement were described by a non-linear concave down response with lizard increasing hourly movement rates up until ˜20 kg body mass before decreasing daily movement suggesting reduced foraging effort in larger lizards. In contrast, home range area exhibited a sigmoid response with increased body mass. Intrapopulation ecological niche use and overlap were also strongly structured by body size. Thus, ontogenetic allometries suggest Komodo dragon's transition from a highly active foraging mode exploiting small prey through to a less active sit and wait feeding strategy focused on killing large ungulates. Further, our results suggest that as body size increases across ontogeny, the Komodo dragon exhibited marked ontogenetic niche shifts that enabled it to function as an entire vertebrate predator guild by exploiting prey across multiple trophic levels.

Under the sea ice: Exploring the relationship between sea ice and the foraging behaviour of southern elephant seals in East Antarctica

NASA Astrophysics Data System (ADS)

Labrousse, Sara; Sallée, Jean-Baptiste; Fraser, Alexander D.; Massom, Robert A.; Reid, Phillip; Sumner, Michael; Guinet, Christophe; Harcourt, Robert; McMahon, Clive; Bailleul, Frédéric; Hindell, Mark A.; Charrassin, Jean-Benoit

2017-08-01

Investigating ecological relationships between predators and their environment is essential to understand the response of marine ecosystems to climate variability and change. This is particularly true in polar regions, where sea ice (a sensitive climate variable) plays a crucial yet highly dynamic and variable role in how it influences the whole marine ecosystem, from phytoplankton to top predators. For mesopredators such as seals, sea ice both supports a rich (under-ice) food resource, access to which depends on local to regional coverage and conditions. Here, we investigate sex-specific relationships between the foraging strategies of southern elephant seals (Mirounga leonina) in winter and spatio-temporal variability in sea ice concentration (SIC) and coverage in East Antarctica. We satellite-tracked 46 individuals undertaking post-moult trips in winter from Kerguelen Islands to the peri-Antarctic shelf between 2004 and 2014. These data indicate distinct general patterns of sea ice usage: while females tended to follow the sea ice edge as it extended northward, the males remained on the continental shelf despite increasing sea ice. Seal hunting time, a proxy of foraging activity inferred from the diving behaviour, was longer for females in late autumn in the outer part of the pack ice, ∼150-370 km south of the ice edge. Within persistent regions of compact sea ice, females had a longer foraging activity (i) in the highest sea ice concentration at their position, but (ii) their foraging activity was longer when there were more patches of low concentration sea ice around their position (either in time or in space; 30 days & 50 km). The high spatio-temporal variability of sea ice around female positions is probably a key factor allowing them to exploit these concentrated patches. Despite lack of information on prey availability, females may exploit mesopelagic finfishes and squids that concentrate near the ice-water interface or within the water column (from diurnal vertical migration) in the pack ice region, likely attracted by an ice algal autumn bloom that sustains an under-ice ecosystem. In contrast, male foraging effort increased when they remained deep within the sea ice (420-960 km from the ice edge) over the shelf. Males had a longer foraging activity (i) in the lowest sea ice concentration at their position, and (ii) when there were more patches of low concentration sea ice around their position (either in time or in space; 30 days & 50 km) presumably in polynyas or flaw leads between land fast and pack ice. This provides access to zones of enhanced resources in autumn or in early spring such as polynyas, the Antarctic shelf and slope. Our results suggest that some seals utilized a highly sea ice covered environment, which is key for their foraging effort, sustaining or concentrating resources during winter.

Effects of colony relocation on diet and productivity of Caspian terns

USGS Publications Warehouse

Roby, D.D.; Collis, K.; Lyons, Donald E.; Craig, D.P.; Adkins, J.Y.; Myers, A.M.; Suryan, R.M.

2002-01-01

We investigated the efficacy of management to reduce the impact of Caspian tern (Sterna caspia) predation on survival of juvenile salmonids (Oncorhynchus spp.) in the Columbia River estuary. Resource managers sought to relocate approximately 9,000 pairs of terns nesting on Rice Island (river km 34) to East Sand Island (river km 8), where terns were expected to prey on fewer juvenile salmonids. Efforts to attract terns to nest on East Sand Island included creation of nesting habitat, use of social attraction techniques, and predator control, with concurrent efforts to discourage terns from nesting on Rice Island. This approach was successful in completely relocating the tern colony from Rice Island to East Sand Island by the third breeding season. Juvenile salmonids decreased and marine forage fishes (i.e., herring, sardine, anchovy, smelt, surfperch, Pacific sand lance) increased in the diet of Caspian terns nesting on East Sand Island, compared with terns nesting on Rice Island. During 1999 and 2000, the diet of terns nesting on Rice Island consisted of 77% and 90% juvenile salmonids, respectively, while during 1999, 2000, and 2001, the diet of terns nesting on East Sand Island consisted of 46%, 47%, and 33% juvenile salmonids, respectively. Nesting success of Caspian terns was consistently and substantially higher on East Sand Island than on Rice Island. These results indicate that relocating the Caspian tern colony was an effective management action for reducing predation on juvenile salmonids without harm to the population of breeding terns, at least in the short term. The success of this management approach largely was a consequence of the nesting and foraging ecology of Caspian terns: the species shifts breeding colony sites frequently in response to changing habitats, and the species is a generalist forager, preying on the most available forage fish near the colony.

Western Juniper Management: Assessing Strategies for Improving Greater Sage-grouse Habitat and Rangeland Productivity

NASA Astrophysics Data System (ADS)

Farzan, Shahla; Young, Derek J. N.; Dedrick, Allison G.; Hamilton, Matthew; Porse, Erik C.; Coates, Peter S.; Sampson, Gabriel

2015-09-01

Western juniper ( Juniperus occidentalis subsp. occidentalis) range expansion into sagebrush steppe ecosystems has affected both native wildlife and economic livelihoods across western North America. The potential listing of the greater sage-grouse ( Centrocercus urophasianus) under the U.S. Endangered Species Act has spurred a decade of juniper removal efforts, yet limited research has evaluated program effectiveness. We used a multi-objective spatially explicit model to identify optimal juniper removal sites in Northeastern California across weighted goals for ecological (sage-grouse habitat) and economic (cattle forage production) benefits. We also extended the analysis through alternative case scenarios that tested the effects of coordination among federal agencies, budgetary constraints, and the use of fire as a juniper treatment method. We found that sage-grouse conservation and forage production goals are somewhat complementary, but the extent of complementary benefits strongly depends on spatial factors and management approaches. Certain management actions substantially increase achievable benefits, including agency coordination and the use of prescribed burns to remove juniper. Critically, our results indicate that juniper management strategies designed to increase cattle forage do not necessarily achieve measurable sage-grouse benefits, underscoring the need for program evaluation and monitoring.

Western juniper management: assessing strategies for improving greater sage-grouse habitat and rangeland productivity

USGS Publications Warehouse

Farzan, Shahla; Young, Derek J.N.; Dedrick, Allison G.; Hamilton, Mattew; Porse, Erik C.; Coates, Peter S.; Sampson, Gabriel

2015-01-01

Western juniper (Juniperus occidentalis subsp. occidentalis) range expansion into sagebrush steppe ecosystems has affected both native wildlife and economic livelihoods across western North America. The potential listing of the greater sage-grouse (Centrocercus urophasianus) under the U.S. Endangered Species Act has spurred a decade of juniper removal efforts, yet limited research has evaluated program effectiveness. We used a multi-objective spatially explicit model to identify optimal juniper removal sites in Northeastern California across weighted goals for ecological (sage-grouse habitat) and economic (cattle forage production) benefits. We also extended the analysis through alternative case scenarios that tested the effects of coordination among federal agencies, budgetary constraints, and the use of fire as a juniper treatment method. We found that sage-grouse conservation and forage production goals are somewhat complementary, but the extent of complementary benefits strongly depends on spatial factors and management approaches. Certain management actions substantially increase achievable benefits, including agency coordination and the use of prescribed burns to remove juniper. Critically, our results indicate that juniper management strategies designed to increase cattle forage do not necessarily achieve measurable sage-grouse benefits, underscoring the need for program evaluation and monitoring.

Avoidance of seismic survey activities by penguins.

PubMed

Pichegru, Lorien; Nyengera, Reason; McInnes, Alistair M; Pistorius, Pierre

2017-11-24

Seismic surveys in search for oil or gas under the seabed, produce the most intense man-made ocean noise with known impacts on invertebrates, fish and marine mammals. No evidence to date exists, however, about potential impacts on seabirds. Penguins may be expected to be particularly affected by loud underwater sounds, due to their largely aquatic existence. This study investigated the behavioural response of breeding endangered African Penguins Spheniscus demersus to seismic surveys within 100 km of their colony in South Africa, using a multi-year GPS tracking dataset. Penguins showed a strong avoidance of their preferred foraging areas during seismic activities, foraging significantly further from the survey vessel when in operation, while increasing their overall foraging effort. The birds reverted to normal behaviour when the operation ceased, although longer-term repercussions on hearing capacities cannot be precluded. The rapid industrialization of the oceans has increased levels of underwater anthropogenic noises globally, a growing concern for a wide range of taxa, now also including seabirds. African penguin numbers have decreased by 70% in the last 10 years, a strong motivation for precautionary management decisions, including the exclusion of seismic exploratory activities within at least 100 km of their breeding colonies.

Western Juniper Management: Assessing Strategies for Improving Greater Sage-grouse Habitat and Rangeland Productivity.

PubMed

Farzan, Shahla; Young, Derek J N; Dedrick, Allison G; Hamilton, Matthew; Porse, Erik C; Coates, Peter S; Sampson, Gabriel

2015-09-01

Western juniper (Juniperus occidentalis subsp. occidentalis) range expansion into sagebrush steppe ecosystems has affected both native wildlife and economic livelihoods across western North America. The potential listing of the greater sage-grouse (Centrocercus urophasianus) under the U.S. Endangered Species Act has spurred a decade of juniper removal efforts, yet limited research has evaluated program effectiveness. We used a multi-objective spatially explicit model to identify optimal juniper removal sites in Northeastern California across weighted goals for ecological (sage-grouse habitat) and economic (cattle forage production) benefits. We also extended the analysis through alternative case scenarios that tested the effects of coordination among federal agencies, budgetary constraints, and the use of fire as a juniper treatment method. We found that sage-grouse conservation and forage production goals are somewhat complementary, but the extent of complementary benefits strongly depends on spatial factors and management approaches. Certain management actions substantially increase achievable benefits, including agency coordination and the use of prescribed burns to remove juniper. Critically, our results indicate that juniper management strategies designed to increase cattle forage do not necessarily achieve measurable sage-grouse benefits, underscoring the need for program evaluation and monitoring.

Ontogenetic prey size selection in snakes: predator size and functional limitations to handling minimum prey sizes.

PubMed

Hampton, Paul M

2018-02-01

As body size increases, some predators eliminate small prey from their diet exhibiting an ontogenetic shift toward larger prey. In contrast, some predators show a telescoping pattern of prey size in which both large and small prey are consumed with increasing predator size. To explore a functional explanation for the two feeding patterns, I examined feeding effort as both handling time and number of upper jaw movements during ingestion of fish of consistent size. I used a range of body sizes from two snake species that exhibit ontogenetic shifts in prey size (Nerodia fasciata and N. rhombifer) and a species that exhibits telescoping prey size with increased body size (Thamnophis proximus). For the two Nerodia species, individuals with small or large heads exhibited greater difficulty in feeding effort compared to snakes of intermediate size. However, for T. proximus measures of feeding effort were negatively correlated with head length and snout-vent length (SVL). These data indicate that ontogenetic shifters of prey size develop trophic morphology large enough that feeding effort increases for disproportionately small prey. I also compared changes in body size among the two diet strategies for active foraging snake species using data gleaned from the literature to determine if increased change in body size and thereby feeding morphology is observable in snakes regardless of prey type or foraging habitat. Of the 30 species sampled from literature, snakes that exhibit ontogenetic shifts in prey size have a greater magnitude of change in SVL than species that have telescoping prey size patterns. Based upon the results of the two data sets above, I conclude that ontogenetic shifts away from small prey occur in snakes due, in part, to growth of body size and feeding structures beyond what is efficient for handling small prey. Copyright © 2017. Published by Elsevier GmbH.

Interactions Increase Forager Availability and Activity in Harvester Ants.

PubMed

Pless, Evlyn; Queirolo, Jovel; Pinter-Wollman, Noa; Crow, Sam; Allen, Kelsey; Mathur, Maya B; Gordon, Deborah M

2015-01-01

Social insect colonies use interactions among workers to regulate collective behavior. Harvester ant foragers interact in a chamber just inside the nest entrance, here called the 'entrance chamber'. Previous studies of the activation of foragers in red harvester ants show that an outgoing forager inside the nest experiences an increase in brief antennal contacts before it leaves the nest to forage. Here we compare the interaction rate experienced by foragers that left the nest and ants that did not. We found that ants in the entrance chamber that leave the nest to forage experienced more interactions than ants that descend to the deeper nest without foraging. Additionally, we found that the availability of foragers in the entrance chamber is associated with the rate of forager return. An increase in the rate of forager return leads to an increase in the rate at which ants descend to the deeper nest, which then stimulates more ants to ascend into the entrance chamber. Thus a higher rate of forager return leads to more available foragers in the entrance chamber. The highest density of interactions occurs near the nest entrance and the entrances of the tunnels from the entrance chamber to the deeper nest. Local interactions with returning foragers regulate both the activation of waiting foragers and the number of foragers available to be activated.

Thermoregulation of water foraging honeybees--balancing of endothermic activity with radiative heat gain and functional requirements.

PubMed

Kovac, Helmut; Stabentheiner, Anton; Schmaranzer, Sigurd

2010-12-01

Foraging honeybees are subjected to considerable variations of microclimatic conditions challenging their thermoregulatory ability. Solar heat is a gain in the cold but may be a burden in the heat. We investigated the balancing of endothermic activity with radiative heat gain and physiological functions of water foraging Apis mellifera carnica honeybees in the whole range of ambient temperatures (T(a)) and solar radiation they are likely to be exposed in their natural environment in Middle Europe. The mean thorax temperature (T(th)) during foraging stays was regulated at a constantly high level (37.0-38.5 °C) in a broad range of T(a) (3-30 °C). At warmer conditions (T(a)=30-39 °C) T(th) increased to a maximal level of 45.3 °C. The endothermic temperature excess (difference of T(body)-T(a) of living and dead bees) was used to assess the endogenously generated temperature elevation as a correlate of energy turnover. Up to a T(a) of ∼30 °C bees used solar heat gain for a double purpose: to reduce energetic expenditure and to increase T(th) by about 1-3 °C to improve force production of flight muscles. At higher T(a) they exhibited cooling efforts to get rid of excess heat. A high T(th) also allowed regulation of the head temperature high enough to guarantee proper function of the bees' suction pump even at low T(a). This shortened the foraging stays and this way reduced energetic costs. With decreasing T(a) bees also reduced arrival body weight and crop loading to do both minimize costs and optimize flight performance. Copyright © 2010 Elsevier Ltd. All rights reserved.

Survival of adult murres and kittiwakes in relation to forage fish abundance

USGS Publications Warehouse

Piatt, John F.

2000-01-01

Some seabird populations damaged by the Exxon Valdez oil spill continue to decline or are not recovering. In order to understand the ultimate cause of seabird population fluctuations, we must measure productivity, recruitment, and adult survival. Recent APEX studies focused on measuring productivity only. Recruitment measurement demands an unrealistic study duration. We propose to augment current studies in lower Cook Inlet that relate breeding success and foraging effort to fluctuations in forage fish density by using banding and resighting to quantify the survival of adult common murres and black-legged kittiwakes.

Factors influencing elk recruitment across ecotypes in the Western United States

USGS Publications Warehouse

Lukacs, Paul M.; Mitchell, Michael S.; Hebblewhite, Mark; Johnson, Bruce K.; Johnson, Heather; Kauffman, Matthew J.; Proffitt, Kelly M.; Zager, Peter; Brodie, Jedediah; Hersey, Kent R.; Holland, A. Andrew; Hurley, Mark; McCorquodale, Scott; Middleton, Arthur; Nordhagen, Matthew; Nowak, J. Joshua; Walsh, Daniel P.; White, P.J.

2018-01-01

Ungulates are key components in ecosystems and economically important for sport and subsistence harvest. Yet the relative importance of the effects of weather conditions, forage productivity, and carnivores on ungulates are not well understood. We examined changes in elk (Cervus canadensis) recruitment (indexed as age ratios) across 7 states and 3 ecotypes in the northwestern United States during 1989–2010, while considering the effects of predator richness, forage productivity, and precipitation. We found a broad‐scale, long‐term decrease in elk recruitment of 0.48 juveniles/100 adult females/year. Weather conditions (indexed as summer and winter precipitation) showed small, but measurable, influences on recruitment. Forage productivity on summer and winter ranges (indexed by normalized difference vegetation index [NDVI] metrics) had the strongest effect on elk recruitment relative to other factors. Relationships between forage productivity and recruitment varied seasonally and regionally. The productivity of winter habitat was more important in southern parts of the study area, whereas annual variation in productivity of summer habitat had more influence on recruitment in northern areas. Elk recruitment varied by up to 15 juveniles/100 adult females across the range of variation in forage productivity. Areas with more species of large carnivores had relatively low elk recruitment, presumably because of increased predation. Wolves (Canis lupus) were associated with a decrease of 5 juveniles/100 adult females, whereas grizzly bears (Ursus arctos) were associated with an additional decrease of 7 juveniles/100 adult females. Carnivore species can have a critical influence on ungulate recruitment because their influence rivals large ranges of variation in environmental conditions. A more pressing concern, however, stems from persistent broad‐scale decreases in recruitment across the distribution of elk in the northwestern United States, irrespective of carnivore richness. Our results suggest that wildlife managers interested in improving recruitment of elk consider the combined effects of habitat and predators. Efforts to manage summer and winter ranges to increase forage productivity may have a positive effect on recruitment. 

Interactions Increase Forager Availability and Activity in Harvester Ants

PubMed Central

Pinter-Wollman, Noa; Crow, Sam; Allen, Kelsey; Mathur, Maya B.; Gordon, Deborah M.

2015-01-01

Social insect colonies use interactions among workers to regulate collective behavior. Harvester ant foragers interact in a chamber just inside the nest entrance, here called the 'entrance chamber'. Previous studies of the activation of foragers in red harvester ants show that an outgoing forager inside the nest experiences an increase in brief antennal contacts before it leaves the nest to forage. Here we compare the interaction rate experienced by foragers that left the nest and ants that did not. We found that ants in the entrance chamber that leave the nest to forage experienced more interactions than ants that descend to the deeper nest without foraging. Additionally, we found that the availability of foragers in the entrance chamber is associated with the rate of forager return. An increase in the rate of forager return leads to an increase in the rate at which ants descend to the deeper nest, which then stimulates more ants to ascend into the entrance chamber. Thus a higher rate of forager return leads to more available foragers in the entrance chamber. The highest density of interactions occurs near the nest entrance and the entrances of the tunnels from the entrance chamber to the deeper nest. Local interactions with returning foragers regulate both the activation of waiting foragers and the number of foragers available to be activated. PMID:26539724

Plant toxicity, adaptive herbivory, and plant community dynamics

USGS Publications Warehouse

Feng, Z.; Liu, R.; DeAngelis, D.L.; Bryant, J.P.; Kielland, K.; Stuart, Chapin F.; Swihart, R.K.

2009-01-01

We model effects of interspecific plant competition, herbivory, and a plant's toxic defenses against herbivores on vegetation dynamics. The model predicts that, when a generalist herbivore feeds in the absence of plant toxins, adaptive foraging generally increases the probability of coexistence of plant species populations, because the herbivore switches more of its effort to whichever plant species is more common and accessible. In contrast, toxin-determined selective herbivory can drive plant succession toward dominance by the more toxic species, as previously documented in boreal forests and prairies. When the toxin concentrations in different plant species are similar, but species have different toxins with nonadditive effects, herbivores tend to diversify foraging efforts to avoid high intakes of any one toxin. This diversification leads the herbivore to focus more feeding on the less common plant species. Thus, uncommon plants may experience depensatory mortality from herbivory, reducing local species diversity. The depensatory effect of herbivory may inhibit the invasion of other plant species that are more palatable or have different toxins. These predictions were tested and confirmed in the Alaskan boreal forest. ?? 2009 Springer Science+Business Media, LLC.

Ultra-High Foraging Rates of Harbor Porpoises Make Them Vulnerable to Anthropogenic Disturbance.

PubMed

Wisniewska, Danuta Maria; Johnson, Mark; Teilmann, Jonas; Rojano-Doñate, Laia; Shearer, Jeanne; Sveegaard, Signe; Miller, Lee A; Siebert, Ursula; Madsen, Peter Teglberg

2016-06-06

The question of how individuals acquire and allocate resources to maximize fitness is central in evolutionary ecology. Basic information on prey selection, search effort, and capture rates are critical for understanding a predator's role in its ecosystem and for predicting its response to natural and anthropogenic disturbance. Yet, for most marine species, foraging interactions cannot be observed directly. The high costs of thermoregulation in water require that small marine mammals have elevated energy intakes compared to similar-sized terrestrial mammals [1]. The combination of high food requirements and their position at the apex of most marine food webs may make small marine mammals particularly vulnerable to changes within the ecosystem [2-4], but the lack of detailed information about their foraging behavior often precludes an informed conservation effort. Here, we use high-resolution movement and prey echo recording tags on five wild harbor porpoises to examine foraging interactions in one of the most metabolically challenged cetacean species. We report that porpoises forage nearly continuously day and night, attempting to capture up to 550 small (3-10 cm) fish prey per hour with a remarkable prey capture success rate of >90%. Porpoises therefore target fish that are smaller than those of commercial interest, but must forage almost continually to meet their metabolic demands with such small prey, leaving little margin for compensation. Thus, for these "aquatic shrews," even a moderate level of anthropogenic disturbance in the busy shallow waters they share with humans may have severe fitness consequences at individual and population levels. Copyright © 2016 Elsevier Ltd. All rights reserved.

Perissodactyla diet

USGS Publications Warehouse

Schoenecker, Kathryn A.

2018-01-01

Perissodactyla (Schoch 1989) includes tapirs, rhinoceros, wild asses, horses, and zebras. It is the order of hoofed mammals referred to as “odd-toed ungulates” because its members have one to three weight-bearing toes and walk on hoofs or “ungules.” They are herbivores that are specialized to exploit grasslands and brushy habitat (rhinos, horses, asses, zebras) or dense tropical forests (tapirs). All share a common digestive system called hindgut fermentation, or cecal digestion (in the cecum), and can consume relatively tough, coarse forage. Some perissodactyls are “browsers” that forage primarily on woody shrubs and trees, whereas others are “grazers” with a graminoid-dominated diet. They are all predominantly opportunistic feeders and select for quantity over quality of forage; that is, they consume more abundant low-quality forage instead of searching and selecting for higher-quality forage because it gives them the advantage of reducing search effort, which conserves energy.

Spatiotemporal resource distribution and foraging strategies of ants (Hymenoptera: Formicidae)

PubMed Central

Lanan, Michele

2014-01-01

The distribution of food resources in space and time is likely to be an important factor governing the type of foraging strategy used by ants. However, no previous systematic attempt has been made to determine whether spatiotemporal resource distribution is in fact correlated with foraging strategy across the ants. In this analysis, I present data compiled from the literature on the foraging strategy and food resource use of 402 species of ants from across the phylogenetic tree. By categorizing the distribution of resources reported in these studies in terms of size relative to colony size, spatial distribution relative to colony foraging range, frequency of occurrence in time relative to worker life span, and depletability (i.e., whether the colony can cause a change in resource frequency), I demonstrate that different foraging strategies are indeed associated with specific spatiotemporal resource attributes. The general patterns I describe here can therefore be used as a framework to inform predictions in future studies of ant foraging behavior. No differences were found between resources collected via short-term recruitment strategies (group recruitment, short-term trails, and volatile recruitment), whereas different resource distributions were associated with solitary foraging, trunk trails, long-term trail networks, group raiding, and raiding. In many cases, ant species use a combination of different foraging strategies to collect diverse resources. It is useful to consider these foraging strategies not as separate options but as modular parts of the total foraging effort of a colony. PMID:25525497

Predictions replaced by facts: a keystone species' behavioural responses to declining arctic sea-ice.

PubMed

Hamilton, Charmain D; Lydersen, Christian; Ims, Rolf A; Kovacs, Kit M

2015-11-01

Since the first documentation of climate-warming induced declines in arctic sea-ice, predictions have been made regarding the expected negative consequences for endemic marine mammals. But, several decades later, little hard evidence exists regarding the responses of these animals to the ongoing environmental changes. Herein, we report the first empirical evidence of a dramatic shift in movement patterns and foraging behaviour of the arctic endemic ringed seal (Pusa hispida), before and after a major collapse in sea-ice in Svalbard, Norway. Among other changes to the ice-regime, this collapse shifted the summer position of the marginal ice zone from over the continental shelf, northward to the deep Arctic Ocean Basin. Following this change, which is thought to be a 'tipping point', subadult ringed seals swam greater distances, showed less area-restricted search behaviour, dived for longer periods, exhibited shorter surface intervals, rested less on sea-ice and did less diving directly beneath the ice during post-moulting foraging excursions. In combination, these behavioural changes suggest increased foraging effort and thus also likely increases in the energetic costs of finding food. Continued declines in sea-ice are likely to result in distributional changes, range reductions and population declines in this keystone arctic species. © 2015 The Author(s).

Environmental and genetic influences on flight metabolic rate in the honey bee, Apis mellifera.

PubMed

Harrison, Jon F; Fewell, Jennifer H

2002-10-01

Flying honey bees demonstrate highly variable metabolic rates. The lowest reported values (approximately 0.3 Wg(-1)) occur in tethered bees generating the minimum lift to support their body weight, free-flying 2-day old bees, winter bees, or bees flying at high air temperatures (45 degrees C). The highest values (approximately 0.8 Wg(-1)) occur in foragers that are heavily loaded or flying in low-density air. In different studies, flight metabolic rate has increased, decreased, or remained constant with air temperature. Current research collectively suggests that this variation occurs because flight metabolic rates decrease at thorax temperatures above or below 38 degrees C. At 30 degrees C, approximately 30% of colonial energy is spent during typical foraging, so variation in flight metabolic rate can strongly affect colony-level energy balance. Higher air temperatures tend to increase colonial net gain rates, efficiencies and honey storage rates due to lower metabolic rates during flight and in the hive. Variation in flight metabolism has a clear genetic basis. Different genetic strains of honey bees often differ in flight metabolic rate, and these differences in flight physiology can be correlated with foraging effort, suggesting a possible pathway for selection effects on flight metabolism.

Positive interactions between irrawaddy dolphins and artisanal fishers in the Chilika Lagoon of eastern India are driven by ecology, socioeconomics, and culture.

PubMed

D'Lima, Coralie; Marsh, Helene; Hamann, Mark; Sinha, Anindya; Arthur, Rohan

2014-09-01

In human-dominated landscapes, interactions and perceptions towards wildlife are influenced by multidimensional drivers. Understanding these drivers could prove useful for wildlife conservation. We surveyed the attitudes and perceptions of fishers towards threatened Irrawaddy dolphins (Orcaella brevirostris) at Chilika Lagoon India. To validate the drivers of fisher perceptions, we : (1) observed dolphin foraging behavior at stake nets, and (2) compared catch per unit effort (CPUE) and catch income of fishers from stake nets in the presence and absence of foraging dolphins. We found that fishers were mostly positive towards dolphins, believing that dolphins augmented their fish catch and using culture to express their perceptions. Foraging dolphins were observed spending half their time at stake nets and were associated with significantly higher catch income and CPUE of mullet (Liza sp.), a locally preferred food fish species. Wildlife conservation efforts should use the multidimensional drivers of human-wildlife interactions to involve local stakeholders in management.

The costs of keeping cool in a warming world: implications of high temperatures for foraging, thermoregulation and body condition of an arid-zone bird.

PubMed

du Plessis, Katherine L; Martin, Rowan O; Hockey, Philip A R; Cunningham, Susan J; Ridley, Amanda R

2012-10-01

Recent mass mortalities of bats, birds and even humans highlight the substantial threats that rising global temperatures pose for endotherms. Although less dramatic, sublethal fitness costs of high temperatures may be considerable and result in changing population demographics. Endothermic animals exposed to high environmental temperatures can adjust their behaviour (e.g. reducing activity) or physiology (e.g. elevating rates of evaporative water loss) to maintain body temperatures within tolerable limits. The fitness consequences of these adjustments, in terms of the ability to balance water and energy budgets and therefore maintain body condition, are poorly known. We investigated the effects of daily maximum temperature on foraging and thermoregulatory behaviour as well as maintenance of body condition in a wild, habituated population of Southern Pied Babblers Turdoides bicolor. These birds inhabit a hot, arid area of southern Africa where they commonly experience environmental temperatures exceeding optimal body temperatures. Repeated measurements of individual behaviour and body mass were taken across days varying in maximum air temperature. Contrary to expectations, foraging effort was unaffected by daily maximum temperature. Foraging efficiency, however, was lower on hotter days and this was reflected in a drop in body mass on hotter days. When maximum air temperatures exceeded 35.5 °C, individuals no longer gained sufficient weight to counter typical overnight weight loss. This reduction in foraging efficiency is likely driven, in part, by a trade-off with the need to engage in heat-dissipation behaviours. When we controlled for temperature, individuals that actively dissipated heat while continuing to forage experienced a dramatic decrease in their foraging efficiency. This study demonstrates the value of investigations of temperature-dependent behaviour in the context of impacts on body condition, and suggests that increasingly high temperatures will have negative implications for the fitness of these arid-zone birds. © 2012 Blackwell Publishing Ltd.

Increased energy expenditure by a seabird in response to higher food abundance

USGS Publications Warehouse

Jodice, P.G.R.; Roby, D.D.; Suryan, R.M.; Irons, D.B.; Turco, K.R.; Brown, E.D.; Thedinga, J.F.; Visser, G. Henk

2006-01-01

Variability in forage fish abundance strongly affects seabird behavior and reproductive success, although details of this relationship are unclear. During 1997 and 1998, we measured (1) daily energy expenditure (DEE) of 80 parent black-legged kittiwakes Rissa tridactyla at 2 colonies in Prince William Sound, Alaska (North Icy Bay and Shoup Bay), (2) abundance of surface-schooling forage fishes within the foraging range of each colony, and (3) diet composition, energy delivery rates to nestlings, and reproductive success of kittiwakes at these same colonies. Female DEE was highest at North Icy Bay in 1998, while male DEE did not differ by colony year. Abundances of Pacific herring Clupea pallasi and sand lance Ammodytes hexapterus were highest near North Icy Bay in 1998 and nearly egual in density, although Age 1+ herring comprised the majority of the diet there. Energy delivery rates to nestlings, nestling growth rates, and productivity were also highest at North Icy Bay in 1998. We suggest that female kittiwakes responded to the increased abundance of Age 1+ herring near North Icy Bay in 1998 by increasing their DEE, which in turn positively affected reproductive success. Given that adult kittiwakes have been shown to suffer decreased survival as a response to increased energy expenditure during brood rearing, the positive correlation we observed between increased abundance of a high quality food source, parental effort, and productivity is consistent with maximizing lifetime reproductive success. The lack of a response in male DEE suggests that brood-rearing roles in kittiwakes differ between genders. ?? Inter-Research 2006.

Characterization of winter foraging locations of Adélie penguins along the Western Antarctic Peninsula, 2001-2002

NASA Astrophysics Data System (ADS)

Erdmann, Eric S.; Ribic, Christine A.; Patterson-Fraser, Donna L.; Fraser, William R.

2011-07-01

In accord with the hypotheses driving the Southern Ocean Global Ocean Ecosystems Dynamics (SO GLOBEC) program, we tested the hypothesis that the winter foraging ecology of a major top predator in waters off the Western Antarctic Peninsula (WAP), the Adélie penguin ( Pygoscelis adeliae), is constrained by oceanographic features related to the physiography of the region. This hypothesis grew from the supposition that breeding colonies in the WAP during summer are located adjacent to areas of complex bathymetry where circulation and upwelling processes appear to ensure predictable food resources. Therefore, we tested the additional hypothesis that these areas continue to contribute to the foraging strategy of this species throughout the non-breeding winter season. We used satellite telemetry data collected as part of the SO GLOBEC program during the austral winters of 2001 and 2002 to characterize individual penguin foraging locations in relation to bathymetry, sea ice variability within the pack ice, and wind velocity and divergence (as a proxy for potential areas with cracks and leads). We also explored differences between males and females in core foraging area overlap. Ocean depth was the most influential variable in the determination of foraging location, with most birds focusing their effort on shallow (<200 m) waters near land and on mixed-layer (200-500 m) waters near the edge of deep troughs. Within-ice variability and wind (as a proxy for potential areas with cracks and leads) were not found to be influential variables, which is likely because of the low resolution satellite imagery and model outputs that were available. Throughout the study period, all individuals maintained a core foraging area separated from other individuals with very little overlap. However, from a year with light sea ice to one with heavy ice cover (2001-2002), we observed an increase in the overlap of individual female foraging areas with those of other birds, likely due to restricted access to the water column, reduced prey abundance, or higher prey concentration. Male birds maintained separate core foraging areas with the same small amount of overlap, showing no difference in overlap between the years. While complex bathymetry was an important physical variable influencing the Adélie penguin's foraging, the analysis of sea ice data of a higher resolution than was available for this study may help elucidate the role of sea ice in affecting Adélie penguin winter foraging behavior within the pack ice.

Characterization of winter foraging locations of Adélie penguins along the Western Antarctic Peninsula, 2001–2002

USGS Publications Warehouse

Erdmann, Eric S.; Ribic, Christine; Patterson-Fraser, Donna L.; Fraser, William R.

2011-01-01

In accord with the hypotheses driving the Southern Ocean Global Ocean Ecosystems Dynamics (SO GLOBEC) program, we tested the hypothesis that the winter foraging ecology of a major top predator in waters off the Western Antarctic Peninsula (WAP), the Adélie penguin (Pygoscelis adeliae), is constrained by oceanographic features related to the physiography of the region. This hypothesis grew from the supposition that breeding colonies in the WAP during summer are located adjacent to areas of complex bathymetry where circulation and upwelling processes appear to ensure predictable food resources. Therefore, we tested the additional hypothesis that these areas continue to contribute to the foraging strategy of this species throughout the non-breeding winter season. We used satellite telemetry data collected as part of the SO GLOBEC program during the austral winters of 2001 and 2002 to characterize individual penguin foraging locations in relation to bathymetry, sea ice variability within the pack ice, and wind velocity and divergence (as a proxy for potential areas with cracks and leads). We also explored differences between males and females in core foraging area overlap. Ocean depth was the most influential variable in the determination of foraging location, with most birds focusing their effort on shallow (<200 m) waters near land and on mixed-layer (200–500 m) waters near the edge of deep troughs. Within-ice variability and wind (as a proxy for potential areas with cracks and leads) were not found to be influential variables, which is likely because of the low resolution satellite imagery and model outputs that were available. Throughout the study period, all individuals maintained a core foraging area separated from other individuals with very little overlap. However, from a year with light sea ice to one with heavy ice cover (2001–2002), we observed an increase in the overlap of individual female foraging areas with those of other birds, likely due to restricted access to the water column, reduced prey abundance, or higher prey concentration. Male birds maintained separate core foraging areas with the same small amount of overlap, showing no difference in overlap between the years. While complex bathymetry was an important physical variable influencing the Adélie penguin's foraging, the analysis of sea ice data of a higher resolution than was available for this study may help elucidate the role of sea ice in affecting Adélie penguin winter foraging behavior within the pack ice.

Variability in sea ice cover and climate elicit sex specific responses in an Antarctic predator

PubMed Central

Labrousse, Sara; Sallée, Jean-Baptiste; Fraser, Alexander D.; Massom, Rob A.; Reid, Phillip; Hobbs, William; Guinet, Christophe; Harcourt, Robert; McMahon, Clive; Authier, Matthieu; Bailleul, Frédéric; Hindell, Mark A.; Charrassin, Jean-Benoit

2017-01-01

Contrasting regional changes in Southern Ocean sea ice have occurred over the last 30 years with distinct regional effects on ecosystem structure and function. Quantifying how Antarctic predators respond to such changes provides the context for predicting how climate variability/change will affect these assemblages into the future. Over an 11-year time-series, we examine how inter-annual variability in sea ice concentration and advance affect the foraging behaviour of a top Antarctic predator, the southern elephant seal. Females foraged longer in pack ice in years with greatest sea ice concentration and earliest sea ice advance, while males foraged longer in polynyas in years of lowest sea ice concentration. There was a positive relationship between near-surface meridional wind anomalies and female foraging effort, but not for males. This study reveals the complexities of foraging responses to climate forcing by a poleward migratory predator through varying sea ice property and dynamic anomalies. PMID:28233791

Variability in sea ice cover and climate elicit sex specific responses in an Antarctic predator.

PubMed

Labrousse, Sara; Sallée, Jean-Baptiste; Fraser, Alexander D; Massom, Rob A; Reid, Phillip; Hobbs, William; Guinet, Christophe; Harcourt, Robert; McMahon, Clive; Authier, Matthieu; Bailleul, Frédéric; Hindell, Mark A; Charrassin, Jean-Benoit

2017-02-24

Contrasting regional changes in Southern Ocean sea ice have occurred over the last 30 years with distinct regional effects on ecosystem structure and function. Quantifying how Antarctic predators respond to such changes provides the context for predicting how climate variability/change will affect these assemblages into the future. Over an 11-year time-series, we examine how inter-annual variability in sea ice concentration and advance affect the foraging behaviour of a top Antarctic predator, the southern elephant seal. Females foraged longer in pack ice in years with greatest sea ice concentration and earliest sea ice advance, while males foraged longer in polynyas in years of lowest sea ice concentration. There was a positive relationship between near-surface meridional wind anomalies and female foraging effort, but not for males. This study reveals the complexities of foraging responses to climate forcing by a poleward migratory predator through varying sea ice property and dynamic anomalies.

Enhancing and restoring habitat for the desert tortoise

USGS Publications Warehouse

Abella, Scott R.; Berry, Kristin H.

2016-01-01

Habitat has changed unfavorably during the past 150 y for the desert tortoise Gopherus agassizii, a federally threatened species with declining populations in the Mojave Desert and western Sonoran Desert. To support recovery efforts, we synthesized published information on relationships of desert tortoises with three habitat features (cover sites, forage, and soil) and candidate management practices for improving these features for tortoises. In addition to their role in soil health and facilitating recruitment of annual forage plants, shrubs are used by desert tortoises for cover and as sites for burrows. Outplanting greenhouse-grown seedlings, protected from herbivory, has successfully restored (>50% survival) a variety of shrubs on disturbed desert soils. Additionally, salvaging and reapplying topsoil using effective techniques is among the more ecologically beneficial ways to initiate plant recovery after severe disturbance. Through differences in biochemical composition and digestibility, some plant species provide better-quality forage than others. Desert tortoises selectively forage on particular annual and herbaceous perennial species (e.g., legumes), and forage selection shifts during the year as different plants grow or mature. Nonnative grasses provide low-quality forage and contribute fuel to spreading wildfires, which damage or kill shrubs that tortoises use for cover. Maintaining a diverse “menu” of native annual forbs and decreasing nonnative grasses are priorities for restoring most desert tortoise habitats. Reducing herbivory by nonnative animals, carefully timing herbicide applications, and strategically augmenting annual forage plants via seeding show promise for improving tortoise forage quality. Roads, another disturbance, negatively affect habitat in numerous ways (e.g., compacting soil, altering hydrology). Techniques such as recontouring road berms to reestablish drainage patterns, vertical mulching (“planting” dead plant material), and creating barriers to prevent trespasses can assist natural recovery on decommissioned backcountry roads. Most habitat enhancement efforts to date have focused on only one factor at a time (e.g., providing fencing) and have not included proactive restoration activities (e.g., planting native species on disturbed soils). A research and management priority in recovering desert tortoise habitats is implementing an integrated set of restorative habitat enhancements (e.g., reducing nonnative plants, improving forage quality, augmenting native perennial plants, and ameliorating altered hydrology) and monitoring short- and long-term indicators of habitat condition and the responses of desert tortoises to habitat restoration.

Conservation and Ecology of Marine Forage Fishes--Proceedings of a Research Symposium, September 2012

USGS Publications Warehouse

Liedtke, Theresa; Gibson, Caroline; Lowry, Dayv; Fagergren, Duane

2013-01-01

Locally and globally, there is growing recognition of the critical roles that herring, smelt, sand lance, eulachon, and other forage fishes play in marine ecosystems. Scientific and resource management entities throughout the Salish Sea, agree that extensive information gaps exist, both in basic biological knowledge and parameters critical to fishery management. Communication and collaboration among researchers also is inadequate. Building on the interest and enthusiasm generated by recent forage fish workshops and symposia around the region, the 2012 Research Symposium on the Conservation and Ecology of Marine Forage Fishes was designed to elucidate practical recommendations for science and policy needs and actions, and spur further collaboration in support for the precautionary management of forage fish. This dynamic and productive event was a joint venture of the Northwest Straits Commission Forage Fish Program, U.S. Geological Survey (USGS), Washington Department of Fish and Wildlife (WDFW), and The Puget Sound Partnership. The symposium was held on September 12–14, 2012, at the University of Washington, Friday Harbor Laboratories campus. Sixty scientists, graduate students, and fisheries policy experts convened; showcasing ongoing research, conservation, and management efforts targeting forage fish from regional and national perspectives. The primary objectives of this event were to: (1) review current research and management related to marine forage fish species; and (2) identify priority science and policy needs and actions for Washington, British Columbia, and the entire West Coast. Given the diversity of knowledge, interests, and disciplines surrounding forage fish on both sides of the international border, the organizing committee made a concerted effort to contact many additional experts who, although unable to attend, provided valuable insights and ideas to the symposium structure and discussions. The value of the symposium format was highlighted in the closing remarks delivered by Joseph Gaydos, SeaDoc Society and Chair of the Puget Sound Science Panel. Dr. Gaydos’ presentation referenced the 2011 paper by Murray Rudd in the journal Conservation Biology, “How research-prioritization exercises affect conservation policy.” The paper points out that policy makers and funding agencies are more likely to gain a full understanding of issues when they are presented with research findings from an aligned research program. That is, compared to unaligned research strategies, where work is not based on identified research priorities.

Subalpine bumble bee foraging distances and densities in relation to flower availability.

PubMed

Elliott, Susan E

2009-06-01

Bees feed almost exclusively on nectar and pollen from flowers. However, little is known about how food availability limits bee populations, especially in high elevation areas. Foraging distances and relationships between forager densities and resource availability can provide insights into the potential for food limitation in mobile consumer populations. For example, if floral resources are limited, bee consumers should fly farther to forage, and they should be more abundant in areas with more flowers. I estimated subalpine bumble bee foraging distances by calculating forager recapture probabilities at increasing distances from eight marking locations. I measured forager and flower densities over the flowering season in six half-hectare plots. Because subalpine bumble bees have little time to build their colonies, they may forage over short distances and forager density may not be constrained by flower density. However, late in the season, when floral resources dwindle, foraging distances may increase, and there may be stronger relationships between forager and flower densities. Throughout the flowering season, marked bees were primarily found within 100 m (and never >1,000 m) from their original marking location, suggesting that they typically did not fly far to forage. Although the density of early season foraging queens increased with early-season flower density, the density of mid- and late-season workers and males did not vary with flower density. Short foraging distances and no relationships between mid- and late-season forager and flower densities suggest that high elevation bumble bees may have ample floral resources for colony growth reproduction.

To walk or to fly? How birds choose among foraging modes

PubMed Central

Bautista, Luis M.; Tinbergen, Joost; Kacelnik, Alejandro

2001-01-01

We test the predictive value of the main energetic currencies used in foraging theory using starlings that choose between two foraging modes (walking versus flying). Walking is low-cost, low-yield, whereas flying is the opposite. We fixed experimentally, at 11 different values, the amount of flight required to get one food reward, and for each flight cost value, we titrated the amount of walking until the birds showed indifference between foraging modes. We then compared the indifference points to those predicted by gross rate of gain over time, net rate of gain over time, and the ratio of gain to expenditure (efficiency). The results for the choice between modes show strong qualitative and quantitative support for net rate of gain over time over the alternatives. However, the birds foraged for only a fraction of the available time, indicating that the choice between foraging and resting could not be explained by any of these currencies. We suggest that this discrepancy could be accounted for functionally because nonenergetic factors such as predation risk may differ between resting and foraging in any mode but may not differ much between foraging modes, hence releasing the choice between foraging modes from the influence of such factors. Alternatively, the discrepancy may be attributable to the use of predictable (rather than stochastic) ratios of effort per prey in our experiment, and it may thus be better understood with mechanistic rather than functional arguments. PMID:11158599

To walk or to fly? How birds choose among foraging modes.

PubMed

Bautista, L M; Tinbergen, J; Kacelnik, A

2001-01-30

We test the predictive value of the main energetic currencies used in foraging theory using starlings that choose between two foraging modes (walking versus flying). Walking is low-cost, low-yield, whereas flying is the opposite. We fixed experimentally, at 11 different values, the amount of flight required to get one food reward, and for each flight cost value, we titrated the amount of walking until the birds showed indifference between foraging modes. We then compared the indifference points to those predicted by gross rate of gain over time, net rate of gain over time, and the ratio of gain to expenditure (efficiency). The results for the choice between modes show strong qualitative and quantitative support for net rate of gain over time over the alternatives. However, the birds foraged for only a fraction of the available time, indicating that the choice between foraging and resting could not be explained by any of these currencies. We suggest that this discrepancy could be accounted for functionally because nonenergetic factors such as predation risk may differ between resting and foraging in any mode but may not differ much between foraging modes, hence releasing the choice between foraging modes from the influence of such factors. Alternatively, the discrepancy may be attributable to the use of predictable (rather than stochastic) ratios of effort per prey in our experiment, and it may thus be better understood with mechanistic rather than functional arguments.

The Physiological Suppressing Factors of Dry Forage Intake and the Cause of Water Intake Following Dry Forage Feeding in Goats — A Review

PubMed Central

Sunagawa, Katsunori; Nagamine, Itsuki

2016-01-01

The goats raised in the barn are usually fed on fresh grass. As dry forage can be stored for long periods in large amounts, dry forage feeding makes it possible to feed large numbers of goats in barns. This review explains the physiological factors involved in suppressing dry forage intake and the cause of drinking following dry forage feeding. Ruminants consume an enormous amount of dry forage in a short time. Eating rates of dry forage rapidly decreased in the first 40 min of feeding and subsequently declined gradually to low states in the remaining time of the feeding period. Saliva in large-type goats is secreted in large volume during the first hour after the commencement of dry forage feeding. It was elucidated that the marked suppression of dry forage intake during the first hour was caused by a feeding-induced hypovolemia and the loss of NaHCO3 due to excessive salivation during the initial stages of dry forage feeding. On the other hand, it was indicated that the marked decrease in feed intake observed in the second hour of the 2 h feeding period was related to ruminal distension caused by the feed consumed and the copious amount of saliva secreted during dry forage feeding. In addition, results indicate that the marked decreases in dry forage intake after 40 min of feeding are caused by increases in plasma osmolality and subsequent thirst sensations produced by dry forage feeding. After 40 min of the 2 h dry forage feeding period, the feed salt content is absorbed into the rumen and plasma osmolality increases. The combined effects of ruminal distension and increased plasma osmolality accounted for 77.6% of the suppression of dry forage intake 40 min after the start of dry forage feeding. The results indicate that ruminal distension and increased plasma osmolality are the main physiological factors in suppression of dry forage intake in large-type goats. There was very little drinking behavior observed during the first hour of the 2 h feeding period most water consumption occurring in the second hour. The cause of this thirst sensation during the second hour of dry forage feeding period was not hypovolemia brought about by excessive salivation, but rather increases in plasma osmolality due to the ruminal absorption of salt from the consumed feed. This suggests the water intake following dry forage feeding is determined by the level of salt content in the feed. PMID:26732440

Sex-specific foraging behaviour in a seabird with reversed sexual dimorphism: the red-footed booby.

PubMed

Weimerskirch, Henri; Le Corre, Matthieu; Ropert-Coudert, Yan; Kato, Akiko; Marsac, Francis

2006-01-01

Most hypotheses attempting to explain the evolution of reversed sexual dimorphism (RSD) assume that size-related differences in foraging ability are of prime importance, but the studies on sex-specific differences in foraging behaviour remain scarce. We compare the foraging behaviour of males and females in a seabird species with a RSD by using several miniaturised activity and telemetry loggers. In red-footed boobies males are 5% smaller and 15% lighter than females, but have a longer tail than females. Both sexes spend similar time on the nest while incubating or brooding. When foraging at sea, males and females spend similar time foraging in oceanic waters, forage in similar areas, spend similar proportion of their foraging trip in flight, and feed on similar prey-flying fishes and flying squids-of similar size. However, compared to males, females range farther during incubation (85 km vs. 50 km), and furthermore feed mostly at the extremity of their foraging trip, whereas males actively forage throughout the trip. Males are much more active than females, landing and diving more often. During the study period, males lost mass, whereas females showed no significant changes. These results indicate that males and females of the red-footed boobies differ in several aspects in their foraging behaviour. Although some differences found in the study may be the direct result of the larger size of females, that is, the slightly higher speeds and deeper depths attained by females, others indicate clearly different foraging strategies between the sexes. The smaller size and longer tail of males confer them a higher agility, and could allow them to occupy a foraging niche different from that of females. The higher foraging effort of males related to its different foraging strategy is probably at the origin of the rapid mass loss of males during the breeding period. These results suggest that foraging differences are probably the reason for the differential breeding investment observed in boobies, and are likely to be involved in the evolution and maintenance of RSD.

Building beef cow nutritional programs with the 1996 NRC beef cattle requirements model.

PubMed

Lardy, G P; Adams, D C; Klopfenstein, T J; Patterson, H H

2004-01-01

Designing a sound cow-calf nutritional program requires knowledge of nutrient requirements, diet quality, and intake. Effectively using the NRC (1996) beef cattle requirements model (1996NRC) also requires knowledge of dietary degradable intake protein (DIP) and microbial efficiency. Objectives of this paper are to 1) describe a framework in which 1996NRC-applicable data can be generated, 2) describe seasonal changes in nutrients on native range, 3) use the 1996NRC to predict nutrient balance for cattle grazing these forages, and 4) make recommendations for using the 1996NRC for forage-fed cattle. Extrusa samples were collected over 2 yr on native upland range and subirrigated meadow in the Nebraska Sandhills. Samples were analyzed for CP, in vitro OM digestibility (IVOMD), and DIP. Regression equations to predict nutrients were developed from these data. The 1996NRC was used to predict nutrient balances based on the dietary nutrient analyses. Recommendations for model users were also developed. On subirrigated meadow, CP and IVOMD increased rapidly during March and April. On native range, CP and IVOMD increased from April through June but decreased rapidly from August through September. Degradable intake protein (DM basis) followed trends similar to CP for both native range and subirrigated meadow. Predicted nutrient balances for spring- and summer-calving cows agreed with reported values in the literature, provided that IVOMD values were converted to DE before use in the model (1.07 x IVOMD - 8.13). When the IVOMD-to-DE conversion was not used, the model gave unrealistically high NE(m) balances. To effectively use the 1996NRC to estimate protein requirements, users should focus on three key estimates: DIP, microbial efficiency, and TDN intake. Consequently, efforts should be focused on adequately describing seasonal changes in forage nutrient content. In order to increase use of the 1996NRC, research is needed in the following areas: 1) cost-effective and accurate commercial laboratory procedures to estimate DIP, 2) reliable estimates or indicators of microbial efficiency for various forage types and qualities, 3) improved estimates of dietary TDN for forage-based diets, 4) validation work to improve estimates of DIP and MP requirements, and 5) incorporation of nitrogen recycling estimates.

Using vertebrate prey capture locations to identify cover type selection patterns of nocturnally foraging Burrowing Owls.

PubMed

Marsh, Alan; Bayne, Erin M; Wellicome, Troy I

2014-07-01

Studies of habitat selection often measure an animal's use of space via radiotelemetry or GPS-based technologies. Such data tend to be analyzed using a resource selection function, despite the fact that the actual resources acquired are typically not recorded. Without explicit proof of resource use, conclusions from RSF models are based on assumptions regarding an animal's behavior and the resources gained. Conservation initiatives are often based on space-use models, and could be detrimental to the target species if these assumptions are incorrect. We used GPS dataloggers and digital video recorders to determine precise locations where nocturnally foraging Burrowing Owls acquired food resources (vertebrate prey). We compared land cover type selection patterns using a presence-only resource selection function (RSF) to a model that incorporated prey capture locations (CRSF). We also compared net prey returns in each cover type to better measure reward relative to foraging effort. The RSF method did not reflect prey capture patterns and cover-type rankings from this model were quite different from models that used only locations where prey was known to have been obtained. Burrowing Owls successfully foraged across all cover types; however, return vs. effort models indicate that different cover types were of higher quality than those identified using resource selection functions. Conclusions about the type of resources acquired should not be made from RSF-style models without evidence that the actual resource of interest was acquired. Conservation efforts based on RSF models alone may be ineffective or detrimental to the target species if the limiting resource and where it is acquired are not properly identified.

Improving legumes for pasture, cover crops, living mulch, and green manure

USDA-ARS?s Scientific Manuscript database

With growing interest in alternative legumes for uses beyond hay, farmers are requesting options to meet their needs. This article explains two efforts in which the U.S. Dairy Forage Research Center is involved. The two efforts include: 1) kura clover seed production so producers have access to kura...

Foraging Behavior and Success of a Mesopelagic Predator in the Northeast Pacific Ocean: Insights from a Data-Rich Species, the Northern Elephant Seal

PubMed Central

Robinson, Patrick W.; Costa, Daniel P.; Crocker, Daniel E.; Gallo-Reynoso, Juan Pablo; Champagne, Cory D.; Fowler, Melinda A.; Goetsch, Chandra; Goetz, Kimberly T.; Hassrick, Jason L.; Hückstädt, Luis A.; Kuhn, Carey E.; Maresh, Jennifer L.; Maxwell, Sara M.; McDonald, Birgitte I.; Peterson, Sarah H.; Simmons, Samantha E.; Teutschel, Nicole M.; Villegas-Amtmann, Stella; Yoda, Ken

2012-01-01

The mesopelagic zone of the northeast Pacific Ocean is an important foraging habitat for many predators, yet few studies have addressed the factors driving basin-scale predator distributions or inter-annual variability in foraging and breeding success. Understanding these processes is critical to reveal how conditions at sea cascade to population-level effects. To begin addressing these challenging questions, we collected diving, tracking, foraging success, and natality data for 297 adult female northern elephant seal migrations from 2004 to 2010. During the longer post-molting migration, individual energy gain rates were significant predictors of pregnancy. At sea, seals focused their foraging effort along a narrow band corresponding to the boundary between the sub-arctic and sub-tropical gyres. In contrast to shallow-diving predators, elephant seals target the gyre-gyre boundary throughout the year rather than follow the southward winter migration of surface features, such as the Transition Zone Chlorophyll Front. We also assessed the impact of added transit costs by studying seals at a colony near the southern extent of the species’ range, 1,150 km to the south. A much larger proportion of seals foraged locally, implying plasticity in foraging strategies and possibly prey type. While these findings are derived from a single species, the results may provide insight to the foraging patterns of many other meso-pelagic predators in the northeast Pacific Ocean. PMID:22615801

A Primer on Foraging and the Explore/Exploit Trade-Off for Psychiatry Research.

PubMed

Addicott, M A; Pearson, J M; Sweitzer, M M; Barack, D L; Platt, M L

2017-09-01

Foraging is a fundamental behavior, and many types of animals appear to have solved foraging problems using a shared set of mechanisms. Perhaps the most common foraging problem is the choice between exploiting a familiar option for a known reward and exploring unfamiliar options for unknown rewards-the so-called explore/exploit trade-off. This trade-off has been studied extensively in behavioral ecology and computational neuroscience, but is relatively new to the field of psychiatry. Explore/exploit paradigms can offer psychiatry research a new approach to studying motivation, outcome valuation, and effort-related processes, which are disrupted in many mental and emotional disorders. In addition, the explore/exploit trade-off encompasses elements of risk-taking and impulsivity-common behaviors in psychiatric disorders-and provides a novel framework for understanding these behaviors within an ecological context. Here we explain relevant concepts and some common paradigms used to measure explore/exploit decisions in the laboratory, review clinically relevant research on the neurobiology and neuroanatomy of explore/exploit decision making, and discuss how computational psychiatry can benefit from foraging theory.

Modelling Pasture-based Automatic Milking System Herds: Grazeable Forage Options

PubMed Central

Islam, M. R.; Garcia, S. C.; Clark, C. E. F.; Kerrisk, K. L.

2015-01-01

One of the challenges to increase milk production in a large pasture-based herd with an automatic milking system (AMS) is to grow forages within a 1-km radius, as increases in walking distance increases milking interval and reduces yield. The main objective of this study was to explore sustainable forage option technologies that can supply high amount of grazeable forages for AMS herds using the Agricultural Production Systems Simulator (APSIM) model. Three different basic simulation scenarios (with irrigation) were carried out using forage crops (namely maize, soybean and sorghum) for the spring-summer period. Subsequent crops in the three scenarios were forage rape over-sown with ryegrass. Each individual simulation was run using actual climatic records for the period from 1900 to 2010. Simulated highest forage yields in maize, soybean and sorghum- (each followed by forage rape-ryegrass) based rotations were 28.2, 22.9, and 19.3 t dry matter/ha, respectively. The simulations suggested that the irrigation requirement could increase by up to 18%, 16%, and 17% respectively in those rotations in El-Niño years compared to neutral years. On the other hand, irrigation requirement could increase by up to 25%, 23%, and 32% in maize, soybean and sorghum based rotations in El-Nino years compared to La-Nina years. However, irrigation requirement could decrease by up to 8%, 7%, and 13% in maize, soybean and sorghum based rotations in La-Nina years compared to neutral years. The major implication of this study is that APSIM models have potentials in devising preferred forage options to maximise grazeable forage yield which may create the opportunity to grow more forage in small areas around the AMS which in turn will minimise walking distance and milking interval and thus increase milk production. Our analyses also suggest that simulation analysis may provide decision support during climatic uncertainty. PMID:25924963

Modelling Pasture-based Automatic Milking System Herds: Grazeable Forage Options.

PubMed

Islam, M R; Garcia, S C; Clark, C E F; Kerrisk, K L

2015-05-01

One of the challenges to increase milk production in a large pasture-based herd with an automatic milking system (AMS) is to grow forages within a 1-km radius, as increases in walking distance increases milking interval and reduces yield. The main objective of this study was to explore sustainable forage option technologies that can supply high amount of grazeable forages for AMS herds using the Agricultural Production Systems Simulator (APSIM) model. Three different basic simulation scenarios (with irrigation) were carried out using forage crops (namely maize, soybean and sorghum) for the spring-summer period. Subsequent crops in the three scenarios were forage rape over-sown with ryegrass. Each individual simulation was run using actual climatic records for the period from 1900 to 2010. Simulated highest forage yields in maize, soybean and sorghum- (each followed by forage rape-ryegrass) based rotations were 28.2, 22.9, and 19.3 t dry matter/ha, respectively. The simulations suggested that the irrigation requirement could increase by up to 18%, 16%, and 17% respectively in those rotations in El-Niño years compared to neutral years. On the other hand, irrigation requirement could increase by up to 25%, 23%, and 32% in maize, soybean and sorghum based rotations in El-Nino years compared to La-Nina years. However, irrigation requirement could decrease by up to 8%, 7%, and 13% in maize, soybean and sorghum based rotations in La-Nina years compared to neutral years. The major implication of this study is that APSIM models have potentials in devising preferred forage options to maximise grazeable forage yield which may create the opportunity to grow more forage in small areas around the AMS which in turn will minimise walking distance and milking interval and thus increase milk production. Our analyses also suggest that simulation analysis may provide decision support during climatic uncertainty.

Dairy cows fed on tropical legume forages: effects on milk yield, nutrients use efficiency and profitability.

PubMed

Castro-Montoya, J M; García, R A; Ramos, R A; Flores, J M; Alas, E A; Corea, E E

2018-04-01

Two trials with multiparous dairy cows were conducted. Experiment 1 tested the effects of increasing forage proportion in the diet (500, 600, and 700 g/kg DM) when a mixed sorghum (Sorghum bicolor) and jackbean (Cannavalia ensiformis) silage was used as forage. Experiment 2 studied the substitution of sorghum silage and soybean meal by jackbean silage or fresh cowpea (Vigna unguiculata) forage in the diet. All diets were iso-energetic and iso-proteic. In each experiment, 30 cows were used and separated into three groups. In experiment 1, there were no differences in dry matter intake (DMI), milk yield (MY), or apparent total tract digestibility (aTTd) among the three diets, but milk fat content increased with increasing forage proportion, even though the similar neutral detergent fiber of all diets. Nitrogen use efficiency was highest in the diet containing 600 g forage/kg DM, and some evidence was observed for a better profitability with this forage proportion. In experiment 2, feeding legumes increased DMI despite no effects on aTTd. Milk yield increased in line with DMI, with a larger increase for the fresh cowpea. Nitrogen use efficiency and milk composition were not affected by the diets. The increased MY and lower feed costs increased the economic benefits when feeding legumes, particularly when feeding fresh cowpea. Feeding fresh cowpea or jackbean silage to dairy cows appears to be an alternative to soybean as protein source, ideally at a forage proportions of 600 g/kg DM, without altering milk yield and quality and increasing the farm profitability.

Nectar profitability, not empty honey stores, stimulate recruitment and foraging in Melipona scutellaris (Apidae, Meliponini).

PubMed

Schorkopf, Dirk Louis P; de Sá Filho, Geovan Figueirêdo; Maia-Silva, Camila; Schorkopf, Martina; Hrncir, Michael; Barth, Friedrich G

2016-10-01

In stingless bees (Meliponini) like in many other eusocial insect colonies food hoarding plays an important role in colony survival. However, very little is known on how Meliponini, a taxon restricted to tropical and subtropical regions, respond to different store conditions. We studied the impact of honey removal on nectar foraging activity and recruitment behaviour in Melipona scutellaris and compared our results with studies of the honey bee Apis mellifera. As expected, foraging activity increased significantly during abundance of artificial nectar and when increasing its profitability. Foraging activity on colony level could thereby frequently increase by an order of magnitude. Intriguingly, however, poor honey store conditions did not induce increased nectar foraging or recruitment activity. We discuss possible reasons explaining why increasing recruitment and foraging activity are not used by meliponines to compensate for poor food conditions in the nest. Among these are meliponine specific adaptations to climatic and environmental conditions, as well as physiology and brood rearing, such as mass provisioning of the brood.

Adult survival, apparent lamb survival, and body condition of desert bighorn sheep in relation to habitat and precipitation on the Kofa National Wildlife Refuge, Arizona

USGS Publications Warehouse

Overstreet, Matthew; Caldwell, Colleen A.; Cain, James W.

2014-01-01

The decline of desert bighorn sheep on the Kofa National Wildlife Refuge (KNWR) beginning in 2003 stimulated efforts to determine the factors limiting survival and recruitment. We 1) determined pregnancy rates, body fat, and estimated survival rates of adults and lambs; 2) investigated the relationship between precipitation, forage conditions, previous year’s reproductive success, and adult body condition; 3) assessed the relative influence of body condition of adult females, precipitation, and forage characteristics on apparent survival of lambs; and 4) determined the prevalence of disease. To assess the influence of potential limiting factors on female desert bighorn sheep on the KNWR, we modeled percent body fat of adult females as a function of previous year’s reproductive effort, age class, and forage conditions (i.e., seasonal NDVI and seasonal precipitation). In addition, we assessed the relative influence of the body condition of adult females, precipitation, and forage conditions (NDVI) on length of time a lamb was observed at heel.Adult female survival was high in both 2009 (0.90 [SE = 0.05]) and 2010 (0.96 [SE = 0.03]). Apparent lamb survival to 6 months of age was 0.23 (SE = 0.05) during 2009-2010 and 0.21 (SE = 0.05) during 2010-2011 lambing seasons. Mean body fat for adult females was 12.03% (SE = 0.479) in 2009-2010 and 11.11% (SE= 0.486) in 2010-2011 and was not significantly different between years. Pregnancy rate was 100% in 2009 and 97.5% in 2010.Models containing the previous year’s reproductive effort, spring NDVI and previous year’s reproductive effort and spring precipitation best approximated data on percent body fat in adult females in 2009-2010. In 2010-2011, the two highest-ranking models included the previous year’s reproductive effort and winter NDVI and previous year’s reproductive effort, and winter and spring NDVI. None of the models assessing the influence of maternal body fat, precipitation, or forage conditions were particularly useful for predicting apparent lamb survival.The high pregnancy rates and body fat levels in excess of 11% do not indicate that this population of desert bighorn was nutritionally stressed during our study and are thus likely not contributing to the low lamb survival estimates we observed. However, body condition data during the population decline is not available and whether this population was nutritionally limited during the initial population decline remains unknown.The prevalence of disease in the Kofa herd may be a limiting factor; however, due to a lack of disease monitoring during the population decline it is uncertain if disease contributed to the decline. Further research is needed to fully understand the complex interaction of disease in this population at the individual and population level and determine to what extent disease predisposes individuals to predation or other causes of mortality.

An Extra Dimension to Decision-Making in Animals: The Three-way Trade-off between Speed, Effort per-Unit-Time and Accuracy

PubMed Central

de Froment, Adrian J.; Rubenstein, Daniel I.; Levin, Simon A.

2014-01-01

The standard view in biology is that all animals, from bumblebees to human beings, face a trade-off between speed and accuracy as they search for resources and mates, and attempt to avoid predators. For example, the more time a forager spends out of cover gathering information about potential food sources the more likely it is to make accurate decisions about which sources are most rewarding. However, when the cost of time spent out of cover rises (e.g. in the presence of a predator) the optimal strategy is for the forager to spend less time gathering information and to accept a corresponding decline in the accuracy of its decisions. We suggest that this familiar picture is missing a crucial dimension: the amount of effort an animal expends on gathering information in each unit of time. This is important because an animal that can respond to changing time costs by modulating its level of effort per-unit-time does not have to accept the same decrease in accuracy that an animal limited to a simple speed-accuracy trade-off must bear in the same situation. Instead, it can direct additional effort towards (i) reducing the frequency of perceptual errors in the samples it gathers or (ii) increasing the number of samples it gathers per-unit-time. Both of these have the effect of allowing it to gather more accurate information within a given period of time. We use a modified version of a canonical model of decision-making (the sequential probability ratio test) to show that this ability to substitute effort for time confers a fitness advantage in the face of changing time costs. We predict that the ability to modulate effort levels will therefore be widespread in nature, and we lay out testable predictions that could be used to detect adaptive modulation of effort levels in laboratory and field studies. Our understanding of decision-making in all species, including our own, will be improved by this more ecologically-complete picture of the three-way tradeoff between time, effort per-unit-time and accuracy. PMID:25522281

An extra dimension to decision-making in animals: the three-way trade-off between speed, effort per-unit-time and accuracy.

PubMed

de Froment, Adrian J; Rubenstein, Daniel I; Levin, Simon A

2014-12-01

The standard view in biology is that all animals, from bumblebees to human beings, face a trade-off between speed and accuracy as they search for resources and mates, and attempt to avoid predators. For example, the more time a forager spends out of cover gathering information about potential food sources the more likely it is to make accurate decisions about which sources are most rewarding. However, when the cost of time spent out of cover rises (e.g. in the presence of a predator) the optimal strategy is for the forager to spend less time gathering information and to accept a corresponding decline in the accuracy of its decisions. We suggest that this familiar picture is missing a crucial dimension: the amount of effort an animal expends on gathering information in each unit of time. This is important because an animal that can respond to changing time costs by modulating its level of effort per-unit-time does not have to accept the same decrease in accuracy that an animal limited to a simple speed-accuracy trade-off must bear in the same situation. Instead, it can direct additional effort towards (i) reducing the frequency of perceptual errors in the samples it gathers or (ii) increasing the number of samples it gathers per-unit-time. Both of these have the effect of allowing it to gather more accurate information within a given period of time. We use a modified version of a canonical model of decision-making (the sequential probability ratio test) to show that this ability to substitute effort for time confers a fitness advantage in the face of changing time costs. We predict that the ability to modulate effort levels will therefore be widespread in nature, and we lay out testable predictions that could be used to detect adaptive modulation of effort levels in laboratory and field studies. Our understanding of decision-making in all species, including our own, will be improved by this more ecologically-complete picture of the three-way tradeoff between time, effort per-unit-time and accuracy.

Effects of large-scale wildfire on ground foraging ants (Hymenoptera: Formicidae) in southern California

USGS Publications Warehouse

Matsuda, Tritia; Turschak, Greta; Brehme, Cheryl; Rochester, Carlton; Mitrovich, Milan; Fisher, Robert

2011-01-01

We investigated the effect of broad-scale wildfire on ground foraging ants within southern California. In October and November of 2003, two wildfires burned large portions of the wildlands within San Diego County. Between January 2005 and September 2006, we surveyed 63 plots across four sites to measure the effect of the fires on the ant assemblages present in four vegetation types: 1) coastal sage scrub, 2) chaparral, 3) grassland, and 4) woodland riparian. Thirty-six of the 63 plots were sampled before the fires between March 2001 and June 2003. Mixed model regression analyses, accounting for the burn history of each plot and our pre- and postfire sampling efforts, revealed that fire had a negative effect on ant species diversity. Multivariate analyses showed that ant community structure varied significantly among the four vegetation types, and only the ant assemblage associated with coastal sage scrub exhibited a significant difference between burned and unburned samples. The most notable change detected at the individual species level involved Messor andrei (Mayr), which increased from <1% of prefire coastal sage scrub ant samples to 32.1% in burned plots postfire. We theorize that M. andrei responded to the increase of bare ground and postfire seed production, leading to an increase in the detection rate for this species. Collectively, our results suggest that wildfires can have short-term impacts on the diversity and community structure of ground foraging ants in coastal sage scrub. We discuss these findings in relation to management implications and directions for future research.

Effect of delignification upon in vitro digestion of forage cellulose.

PubMed

Darcy, B K; Belyea, R L

1980-10-01

Orchardgrass forages harvested at two maturities (early and late) were ground through two screens (1 and 8 mm) and digested in vitro as intact forage and forage delignified by permanganate oxidation. Initial and residual cell wall, initial and residual cellulose and potentially digestible cellulose were greater in late intact forage than in the early. In the delignified forage, late cut forage had less residual cellulose than did the early, but initial and potentially digestible cellulose were similar. Particle size had less consistent and smaller effects upon cell wall and cellulose than did maturity. Cellulose of intact orchardgrass was 64% digested at 72 h vs 94% for cellulose of delignified orchardgrass. Digestion rate of cellulose was .0197 and .0220 logn units/hr for early and late cut intact forage and .0554 and .0719 logn units/hr for early and late cut delignified forage. Removal of the inhibitory effects of lignin increased the amount of digestible cellulose, increased the rate at which cellulose degraded and decreased the indigestible cellulose residue. Reduction in lignin could greatly improve forage intake and utilization at moderate levels of animal production.

Dynamic oceanography determines fine scale foraging behavior of Masked Boobies in the Gulf of Mexico

PubMed Central

Harrison, Autumn-Lynn; Vallarino, Adriana; Gerard, Patrick D.; Jodice, Patrick G. R.

2017-01-01

During breeding, foraging marine birds are under biological, geographic, and temporal constraints. These contraints require foraging birds to efficiently process environmental cues derived from physical habitat features that occur at nested spatial scales. Mesoscale oceanography in particular may change rapidly within and between breeding seasons, and findings from well-studied systems that relate oceanography to seabird foraging may transfer poorly to regions with substantially different oceanographic conditions. Our objective was to examine foraging behavior of a pan-tropical seabird, the Masked Booby (Sula dactylatra), in the understudied Caribbean province, a moderately productive region driven by highly dynamic currents and fronts. We tracked 135 individuals with GPS units during May 2013, November 2013, and December 2014 at a regionally important breeding colony in the southern Gulf of Mexico. We measured foraging behavior using characteristics of foraging trips and used area restricted search as a proxy for foraging events. Among individual attributes, nest stage contributed to differences in foraging behavior whereas sex did not. Birds searched for prey at nested hierarchical scales ranging from 200 m—35 km. Large-scale coastal and shelf-slope fronts shifted position between sampling periods and overlapped geographically with overall foraging locations. At small scales (at the prey patch level), the specific relationship between environmental variables and foraging behavior was highly variable among individuals but general patterns emerged. Sea surface height anomaly and velocity of water were the strongest predictors of area restricted search behavior in random forest models, a finding that is consistent with the characterization of the Gulf of Mexico as an energetic system strongly influenced by currents and eddies. Our data may be combined with tracking efforts in the Caribbean province and across tropical regions to advance understanding of seabird sensing of the environment and serve as a baseline for anthropogenic based threats such as development, pollution, and commercial fisheries. PMID:28575078

Dynamic oceanography determines fine scale foraging behavior of Masked Boobies in the Gulf of Mexico.

PubMed

Poli, Caroline L; Harrison, Autumn-Lynn; Vallarino, Adriana; Gerard, Patrick D; Jodice, Patrick G R

2017-01-01

During breeding, foraging marine birds are under biological, geographic, and temporal constraints. These contraints require foraging birds to efficiently process environmental cues derived from physical habitat features that occur at nested spatial scales. Mesoscale oceanography in particular may change rapidly within and between breeding seasons, and findings from well-studied systems that relate oceanography to seabird foraging may transfer poorly to regions with substantially different oceanographic conditions. Our objective was to examine foraging behavior of a pan-tropical seabird, the Masked Booby (Sula dactylatra), in the understudied Caribbean province, a moderately productive region driven by highly dynamic currents and fronts. We tracked 135 individuals with GPS units during May 2013, November 2013, and December 2014 at a regionally important breeding colony in the southern Gulf of Mexico. We measured foraging behavior using characteristics of foraging trips and used area restricted search as a proxy for foraging events. Among individual attributes, nest stage contributed to differences in foraging behavior whereas sex did not. Birds searched for prey at nested hierarchical scales ranging from 200 m-35 km. Large-scale coastal and shelf-slope fronts shifted position between sampling periods and overlapped geographically with overall foraging locations. At small scales (at the prey patch level), the specific relationship between environmental variables and foraging behavior was highly variable among individuals but general patterns emerged. Sea surface height anomaly and velocity of water were the strongest predictors of area restricted search behavior in random forest models, a finding that is consistent with the characterization of the Gulf of Mexico as an energetic system strongly influenced by currents and eddies. Our data may be combined with tracking efforts in the Caribbean province and across tropical regions to advance understanding of seabird sensing of the environment and serve as a baseline for anthropogenic based threats such as development, pollution, and commercial fisheries.

Dynamic oceanography determines fine scale foraging behavior of Masked Boobies in the Gulf of Mexico

USGS Publications Warehouse

Poli, Caroline L.; Harrison, Autumn-Lynn; Vallarino, Adriana; Gerard, Patrick D.; Jodice, Patrick G.R.

2017-01-01

During breeding, foraging marine birds are under biological, geographic, and temporal constraints. These contraints require foraging birds to efficiently process environmental cues derived from physical habitat features that occur at nested spatial scales. Mesoscale oceanography in particular may change rapidly within and between breeding seasons, and findings from well-studied systems that relate oceanography to seabird foraging may transfer poorly to regions with substantially different oceanographic conditions. Our objective was to examine foraging behavior of a pan-tropical seabird, the Masked Booby (Sula dactylatra), in the understudied Caribbean province, a moderately productive region driven by highly dynamic currents and fronts. We tracked 135 individuals with GPS units during May 2013, November 2013, and December 2014 at a regionally important breeding colony in the southern Gulf of Mexico. We measured foraging behavior using characteristics of foraging trips and used area restricted search as a proxy for foraging events. Among individual attributes, nest stage contributed to differences in foraging behavior whereas sex did not. Birds searched for prey at nested hierarchical scales ranging from 200 m—35 km. Large-scale coastal and shelf-slope fronts shifted position between sampling periods and overlapped geographically with overall foraging locations. At small scales (at the prey patch level), the specific relationship between environmental variables and foraging behavior was highly variable among individuals but general patterns emerged. Sea surface height anomaly and velocity of water were the strongest predictors of area restricted search behavior in random forest models, a finding that is consistent with the characterization of the Gulf of Mexico as an energetic system strongly influenced by currents and eddies. Our data may be combined with tracking efforts in the Caribbean province and across tropical regions to advance understanding of seabird sensing of the environment and serve as a baseline for anthropogenic based threats such as development, pollution, and commercial fisheries.

Thermoregulation of dancing bees: thoracic temperature of pollen and nectar foragers in relation to profitability of foraging and colony need.

PubMed

Stabentheiner, A

2001-04-01

The thorax surface temperature of dancing honeybees (Apis mellifera carnica) recruiting nestmates to natural sources of nectar and pollen around Graz (Austria) was measured by real-time infrared thermography without touching them or disturbing social interactions. Thorax temperature during dancing was quite variable (31.4-43 degrees C). In the course of a foraging season it varied considerably and was always lower than in bees foraging from a highly profitable food source (2 molar sucrose 120 m from the hive). It averaged 38.0 degrees C (SD=2.24, n=224 dances) in the nectar foragers and 37.4 degrees C (SD=1.64, n=171) in the pollen foragers, resembling that of dancers foraging 0.5 molar sucrose from feeders with unlimited flow. Hive air temperature accounted only for about 3-8% of total variation. Foraging distance modulated dancing temperature in a way that, according to the decrease of the profitability of foraging with distance, maximum temperatures decreased and, in accordance with the increase of the dancing threshold with distance, minumum temperatures increased with distance, this way providing new support for the hypothesis that the dancing temperature is modulated by the profitability of foraging and the dancing and foraging motivation of the bees. Dancing temperature of both nectar and pollen dancers correlated with several parameters of the hive status, increasing with the amount of brood and decreasing with the amount of honey and pollen. These correlations are discussed with respect to literature reports on a colony's need for pollen and nectar, in particular the effect of brood and the amount of pollen on pollen foraging, and the effect of honey stores and demand for nectar on nectar foraging.

Effects of dietary forage level and monensin on lactation performance, digestibility and fecal excretion of nutrients, and efficiency of feed nitrogen utilization of Holstein dairy cows.

PubMed

Martinez, C M; Chung, Y-H; Ishler, V A; Bailey, K W; Varga, G A

2009-07-01

Two experiments (Exp. 1 and 2) were conducted using a 4 x 4 Latin square design with 2 replications (n = 8) to evaluate effects of feeding Holstein dairy cows a total mixed ration containing 50 or 60% of ration dry matter (DM) from forages with or without supplementation of monensin. In Exp. 1, alfalfa silage (AS) was used as the major forage (55% forage DM), and corn silage (CS; 45% forage DM) was used to make up the rest of the forage portion of diets (55AS:45CS). In Exp. 2, CS was used as the major forage (70% forage DM) and alfalfa hay (AH; 30% forage DM) was used to make up the rest of the forage portion of diets (70CS:30AH). Experimental diets were arranged in a 2 x 2 factorial with 50 or 60% ration DM from forages and monensin supplemented at 0 or 300 mg/cow daily. In Exp. 1 (55AS:45CS), feeding 60% forage diets decreased DM intake (DMI; 27.3 vs. 29.6 kg/d) but maintained the same levels of milk (45.8 vs. 47.0 kg/d) compared with 50% forage diets. The efficiency of converting feed to milk or 3.5% fat-corrected milk was greater for cows fed 60% compared with 50% forage diets (1.7 vs. 1.6 kg milk or 3.5% fat-corrected milk/kg of DMI, respectively). Increasing dietary forage level from 50 to 60% of ration DM increased milk fat percentage (3.4 to 3.5%); however, adding monensin to the 60% forage diet inhibited the increase in milk fat percentage. Feeding 60% forage diets decreased feed cost, but this decrease ($0.5/head per day) in feed cost did not affect income over feed cost. Feeding 60% forage diets decreased fecal excretion of DM (10.6 to 9.6 kg/d) and nitrogen (N; 354 to 324 g/d) and improved apparent digestibility of neutral detergent fiber from 43 to 49% and apparent efficiency of feed N utilization from 32.3 to 35.9% compared with 50% forage diets. In Exp. 2 (70CS:30AH), feeding 60% forage diets decreased DMI from 29.6 to 28.2 kg but maintained the same level of milk (41.1 vs. 40.8 kg/d) and therefore increased the efficiency of converting feed to milk (1.46 vs. 1.38 kg milk/kg DMI) compared with 50% forage diets. Daily feed cost for feeding 60% forage diets was $0.3/head lower than for the 50% forage diets. Fecal excretion of DM (10.3 vs. 11.5 kg/d) was lower and fecal excretion of N (299 vs. 328 g/d) tended to be lower for 60% compared with 50% forage diets. Results from these 2 experiments suggest that a 60% forage diet consisting of either AS or CS as the major forage can be fed to high producing Holstein dairy cows without affecting milk production while improving or maintaining the efficiency of converting feed to milk and the apparent efficiency of utilization of feed N. Cows receiving a 60% forage diet had a similar or improved digestibility of nutrients with a similar or reduced fecal excretion of nutrients. Effects of monensin under the conditions of the current experiments were minimal.

Thermal and digestive constraints to foraging behaviour in marine mammals.

PubMed

Rosen, David A S; Winship, Arliss J; Hoopes, Lisa A

2007-11-29

While foraging models of terrestrial mammals are concerned primarily with optimizing time/energy budgets, models of foraging behaviour in marine mammals have been primarily concerned with physiological constraints. This has historically centred on calculations of aerobic dive limits. However, other physiological limits are key to forming foraging behaviour, including digestive limitations to food intake and thermoregulation. The ability of an animal to consume sufficient prey to meet its energy requirements is partly determined by its ability to acquire prey (limited by available foraging time, diving capabilities and thermoregulatory costs) and process that prey (limited by maximum digestion capacity and the time devoted to digestion). Failure to consume sufficient prey will have feedback effects on foraging, thermoregulation and digestive capacity through several interacting avenues. Energy deficits will be met through catabolism of tissues, principally the hypodermal lipid layer. Depletion of this blubber layer can affect both buoyancy and gait, increasing the costs and decreasing the efficiency of subsequent foraging attempts. Depletion of the insulative blubber layer may also increase thermoregulatory costs, which will decrease the foraging abilities through higher metabolic overheads. Thus, an energy deficit may lead to a downward spiral of increased tissue catabolism to pay for increased energy costs. Conversely, the heat generated through digestion and foraging activity may help to offset thermoregulatory costs. Finally, the circulatory demands of diving, thermoregulation and digestion may be mutually incompatible. This may force animals to alter time budgets to balance these exclusive demands. Analysis of these interacting processes will lead to a greater understanding of the physiological constraints within which the foraging behaviour must operate.

Characteristics of lambs fed concentrates or grazed on ryegrass to traditional or heavy slaughter weights. II. Wholesale cuts and tissue accretion.

PubMed

Borton, R J; Loerch, S C; McClure, K E; Wulf, D M

2005-06-01

Targhee x Hampshire lambs (average BW 24 +/- 1 kg) were used to determine the effect of finishing on concentrate or by grazing ryegrass forage on slaughter weights of 52 kg (N) or 77 kg (H) on tissue accretion and lamb wholesale cutout. When fed to similar slaughter weights, the wholesale cuts of concentrate-fed lambs were heavier (P < 0.05) than the same cuts from forage-fed lambs; however, when expressed as a percentage of side weight, carcasses of forage-fed lambs had a higher (P < 0.001) percentage of leg than concentrate-fed lambs. Increasing slaughter weight from 52 to 77 kg resulted in a 1-kg increase in loin weight for lambs finished on concentrate and a 0.60-kg increase for lambs finished on forage (diet x slaughter weight, P < 0.03); however, the increased loin weight for lambs finished on concentrate was due largely to increased fat deposition. For lambs slaughtered at 77 kg, those finished on forage had more lean mass in the leg, loin, rack, and shoulder than those finished on concentrate, but lean mass in these cuts did not differ between diets for lambs slaughtered at 52 kg (diet x slaughter weight, P < 0.01). At the normal slaughter weight (52 kg), concentrate-fed lambs had 50% more dissectible fat than forage-fed lambs, whereas at the heavy slaughter weight, a 79% greater amount of dissectible fat was observed for concentrate- vs. forage-fed lambs (diet x slaughter weight, P < 0.001). Lean and fat accretion rates were higher (P < 0.001) for concentrate-fed lambs than for forage-fed lambs. The lean-to-fat ratio of forage-fed lambs was higher (P < 0.001) than that of concentrate-fed lambs; however, forage finishing decreased accretion rates of all tissues compared with concentrate feeding, and these differences between forage and concentrate feeding were magnified at heavier slaughter weights.

Worker honey bee pheromone regulation of foraging ontogeny

NASA Astrophysics Data System (ADS)

Pankiw, Tanya

The evolution of sociality has configured communication chemicals, called primer pheromones, which play key roles in regulating the organization of social life. Primer pheromones exert relatively slow effects that fundamentally alter developmental, physiological, and neural systems. Here, I demonstrate how substances extracted from the surface of foraging and young pre-foraging worker bees regulated age at onset of foraging, a developmental process. Hexane-extractable compounds washed from foraging workers increased foraging age compared with controls, whereas extracts of young pre-foraging workers decreased foraging age. This represents the first known direct demonstration of primer pheromone activity derived from adult worker bees.

The foraging benefits of being fat in a highly migratory marine mammal

PubMed Central

Adachi, Taiki; Maresh, Jennifer L.; Robinson, Patrick W.; Peterson, Sarah H.; Costa, Daniel P.; Naito, Yasuhiko; Watanabe, Yuuki Y.; Takahashi, Akinori

2014-01-01

Foraging theory predicts that breath-hold divers adjust the time spent foraging at depth relative to the energetic cost of swimming, which varies with buoyancy (body density). However, the buoyancy of diving animals varies as a function of their body condition, and the effects of these changes on swimming costs and foraging behaviour have been poorly examined. A novel animal-borne accelerometer was developed that recorded the number of flipper strokes, which allowed us to monitor the number of strokes per metre swam (hereafter, referred to as strokes-per-metre) by female northern elephant seals over their months-long, oceanic foraging migrations. As negatively buoyant seals increased their fat stores and buoyancy, the strokes-per-metre increased slightly in the buoyancy-aided direction (descending), but decreased significantly in the buoyancy-hindered direction (ascending), with associated changes in swim speed and gliding duration. Overall, the round-trip strokes-per-metre decreased and reached a minimum value when seals achieved neutral buoyancy. Consistent with foraging theory, seals stayed longer at foraging depths when their round-trip strokes-per-metre was less. Therefore, neutrally buoyant divers gained an energetic advantage via reduced swimming costs, which resulted in an increase in time spent foraging at depth, suggesting a foraging benefit of being fat. PMID:25377461

Nighttime foraging by deep diving echolocating odontocetes off the Hawaiian islands of Kauai and Ni'ihau as determined by passive acoustic monitors.

PubMed

Au, Whitlow W L; Giorli, Giacomo; Chen, Jessica; Copeland, Adrienne; Lammers, Marc; Richlen, Michael; Jarvis, Susan; Morrissey, Ronald; Moretti, David; Klinck, Holger

2013-05-01

Remote autonomous ecological acoustic recorders (EARs) were deployed in deep waters at five locations around the island of Kauai and one in waters off Ni'ihau in the main Hawaiian island chain. The EARs were moored to the bottom at depths between 400 and 800 m. The data acquisition sampling rate was 80 kHz and acoustic signals were recorded for 30 s every 5 min to conserve battery power and disk space. The acoustic data were analyzed with the M3R (Marine Mammal Monitoring on Navy Ranges) software, an energy-ratio-mapping algorithm developed at Oregon State University and custom MATLAB programs. A variety of deep diving odontocetes, including pilot whales, Risso's dolphins, sperm whales, spinner and pan-tropical spotted dolphins, and beaked whales were detected at all sites. Foraging activity typically began to increase after dusk, peaked in the middle of the night and began to decrease toward dawn. Between 70% and 84% of biosonar clicks were detected at night. At present it is not clear why some of the known deep diving species, such as sperm whales and beaked whales, concentrate their foraging efforts at night.

Predictive ethoinformatics reveals the complex migratory behaviour of a pelagic seabird, the Manx Shearwater

PubMed Central

Freeman, Robin; Dean, Ben; Kirk, Holly; Leonard, Kerry; Phillips, Richard A.; Perrins, Chris M.; Guilford, Tim

2013-01-01

Understanding the behaviour of animals in the wild is fundamental to conservation efforts. Advances in bio-logging technologies have offered insights into the behaviour of animals during foraging, migration and social interaction. However, broader application of these systems has been limited by device mass, cost and longevity. Here, we use information from multiple logger types to predict individual behaviour in a highly pelagic, migratory seabird, the Manx Shearwater (Puffinus puffinus). Using behavioural states resolved from GPS tracking of foraging during the breeding season, we demonstrate that individual behaviours can be accurately predicted during multi-year migrations from low cost, lightweight, salt-water immersion devices. This reveals a complex pattern of migratory stopovers: some involving high proportions of foraging, and others of rest behaviour. We use this technique to examine three consecutive years of global migrations, revealing the prominence of foraging behaviour during migration and the importance of highly productive waters during migratory stopover. PMID:23635496

Subglacial discharges create fluctuating foraging hotspots for sea birds in tidewater glacier bays.

PubMed

Urbanski, Jacek Andrzej; Stempniewicz, Lech; Węsławski, Jan Marcin; Dragańska-Deja, Katarzyna; Wochna, Agnieszka; Goc, Michał; Iliszko, Lech

2017-03-07

Although the processes occurring at the front of an ice face in tidewater glacier bays still await thorough investigation, their importance to the rapidly changing polar environment is spurring a considerable research effort. Glacier melting, sediment delivery and the formation of seabird foraging hotspots are governed by subglacial discharges of meltwater. We have combined the results of tracking black-legged kittiwakes Rissa tridactyla equipped with GPS loggers, analyses of satellite images and in situ measurements of water temperature, salinity and turbidity in order to examine the magnitude and variability of such hotspots in the context of glacier bay hydrology. Small though these hotspots are in size, foraging in them appears to be highly intensive. They come into existence only if the subglacial discharge reaches the surface, if the entrainment velocity at a conduit is high and if there is sufficient macroplankton in the entrainment layer. The position and type of subglacial discharges may fluctuate in time and space, thereby influencing glacier bay hydrology and the occurrence of foraging hotspots.

Resource diversity and landscape-level homogeneity drive native bee foraging.

PubMed

Jha, Shalene; Kremen, Claire

2013-01-08

Given widespread declines in pollinator communities and increasing global reliance on pollinator-dependent crops, there is an acute need to develop a mechanistic understanding of native pollinator population and foraging biology. Using a population genetics approach, we determine the impact of habitat and floral resource distributions on nesting and foraging patterns of a critical native pollinator, Bombus vosnesenskii. Our findings demonstrate that native bee foraging is far more plastic and extensive than previously believed and does not follow a simple optimal foraging strategy. Rather, bumble bees forage further in pursuit of species-rich floral patches and in landscapes where patch-to-patch variation in floral resources is less, regardless of habitat composition. Thus, our results reveal extreme foraging plasticity and demonstrate that floral diversity, not density, drives bee foraging distance. Furthermore, we find a negative impact of paved habitat and a positive impact of natural woodland on bumble bee nesting densities. Overall, this study reveals that natural and human-altered landscapes can be managed for increased native bee nesting and extended foraging, dually enhancing biodiversity and the spatial extent of pollination services.

Apparent ruminal synthesis of B vitamins in lactating dairy cows fed diets with different forage-to-concentrate ratios.

PubMed

Seck, M; Linton, J A Voelker; Allen, M S; Castagnino, D S; Chouinard, P Y; Girard, C L

2017-03-01

Effects of the forage-to-concentrate ratio on apparent ruminal synthesis of thiamine, riboflavin, niacin, vitamin B 6 , folates, and vitamin B 12 were evaluated in an experiment using 14 ruminally and duodenally cannulated Holstein cows. The experiment was a crossover design with two 15-d treatment periods and a 14-d preliminary period in which cows were fed a diet intermediate in composition between the treatment diets. Treatments were diets containing low-forage (44.8% forage, 32.8% starch, 24.4% neutral detergent fiber) or high-forage (61.4% forage, 22.5% starch, 30.7% neutral detergent fiber) concentrations. Both diets were formulated with different proportions of the same ingredients. Concentrations of B vitamins were analyzed in feed and duodenal digesta. Apparent ruminal synthesis of each B vitamin was calculated as the duodenal flow minus the intake. The high-forage diet had the highest concentrations of riboflavin, niacin, vitamin B 6 , and folates, whereas the low-forage diet had the highest thiamine concentration. Vitamin B 12 in the diets was under the level of detection. Consequently, despite a reduction in dry matter intake when the cows were fed the high-forage diet, increasing dietary forage concentration increased or tended to increase intakes of riboflavin, niacin, and vitamin B 6 but reduced thiamine and folate intakes. Increasing dietary forage concentration reduced apparent ruminal degradation of thiamine and apparent ruminal synthesis of riboflavin, niacin, and folates and increased ruminal degradation of vitamin B 6 , but had no effect on ruminal synthesis of vitamin B 12 . As a consequence, increasing the forage-to-concentrate ratio had no effect on the amounts of thiamine, riboflavin, and vitamin B 12 reaching the small intestine but decreased the amounts of niacin, vitamin B 6 , and folates available for absorption. Apparent ruminal syntheses of riboflavin, niacin, folates, and vitamin B 12 were correlated positively with the amount of starch digested in the rumen and duodenal flow of microbial N, whereas these correlations were negative for thiamine. Apparent ruminal syntheses of thiamine and vitamin B 6 were negatively correlated with their respective intakes, whereas folate intake was positively correlated with its synthesis in the rumen. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Ozone and sulfur dioxide effects on tall fescue. II. Alteration of quality constituents. [Festuca arundinacea

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flagler, R.B.; Youngner, V.B.

A greenhouse study was conducted to determine whether ozone (O/sub 3/) and sulfur dioxide (SO/sub 2/) might alter forage quality parameters of tall fescue (Festuca arundinacea Schreb. Alta). Plants were exposed weekly to four O/sub 3/ treatments, 0, 0.10, 0.20, and 0.30 ..mu..L L/sup -1/; with or without 0.10 ..mu..L L/sup -1/ SO/sub 2/, 6 h d/sup -1/ for 12 weeks. Ozone had a much greater impact on forage quality than did SO/sub 2/. Ozone increased protein content on a g kg/sup -1/ basis and decreased protein on a weight per plant basis. Ozone reduced crude fat, crude fiber, andmore » total nonstructural carbohydrate contents of the forage. Crude ash content increased due to O/sub 3/ exposure. On a weight per plant basis, O/sub 3/ decreased the forage concentration of Ca, Mg, and P. Ozone increased Ca concentration of herbage. Sulfur dioxide increased ash content of the forage. Phosphorus concentration and weight per plant of Mg and P were all reduced by SO/sub 2/ Significant pollutant interactions occurred for crude fiber, crude ash, total Mg, and total P contents of forage. While treatments resulted in some apparent increases in forage quality, these were at the expense of yield. The most adverse effects on forage quality were an increase in ash content which resulted from an interaction of SO/sub 2/ with O/sub 3/, and a reduction in soluble carbohydrate content of shoots due to O/sub 3/.« less

Forage accumulation and nutritive value of reduced lignin and reference alfalfa cultivars

USDA-ARS?s Scientific Manuscript database

Reduced lignin alfalfa (Medicago sativa L.) cultivars have the potential to increase the feeding value of alfalfa for livestock by improving the forage fiber digestibility and to increase harvest management flexibility. The objectives were to compare the yield and forage nutritive value of reduced ...

Forages and pastures symposium: Animal performance and environmental efficiency of cool-and warm-season annual grazing systems

USDA-ARS?s Scientific Manuscript database

Annual forage crops can provide short-term grazing between crop rotations or can be interseeded into perennial pastures to increase forage quality and productivity. They also provide an opportunity to increase the economic and environmental sustainability of traditional grazing systems. Cool-season ...

Root foraging increases performance of the clonal plant Potentilla reptans in heterogeneous nutrient environments.

PubMed

Wang, Zhengwen; van Kleunen, Mark; During, Heinjo J; Werger, Marinus J A

2013-01-01

Plastic root-foraging responses have been widely recognized as an important strategy for plants to explore heterogeneously distributed resources. However, the benefits and costs of root foraging have received little attention. In a greenhouse experiment, we grew pairs of connected ramets of 22 genotypes of the stoloniferous plant Potentilla reptans in paired pots, between which the contrast in nutrient availability was set as null, medium and high, but with the total nutrient amount kept the same. We calculated root-foraging intensity of each individual ramet pair as the difference in root mass between paired ramets divided by the total root mass. For each genotype, we then calculated root-foraging ability as the slope of the regression of root-foraging intensity against patch contrast. For all genotypes, root-foraging intensity increased with patch contrast and the total biomass and number of offspring ramets were lowest at high patch contrast. Among genotypes, root-foraging intensity was positively related to production of offspring ramets and biomass in the high patch-contrast treatment, which indicates an evolutionary benefit of root foraging in heterogeneous environments. However, we found no significant evidence that the ability of plastic foraging imposes costs under homogeneous conditions (i.e. when foraging is not needed). Our results show that plants of P. reptans adjust their root-foraging intensity according to patch contrast. Moreover, the results show that the root foraging has an evolutionary advantage in heterogeneous environments, while costs of having the ability of plastic root foraging were absent or very small.

First steps for mitigating bycatch of Pink-footed Shearwaters Ardenna creatopus: Identifying overlap of foraging areas and fisheries in Chile

USGS Publications Warehouse

Carle, Ryan; Felis, Jonathan J.; López, Verónica; Adams, Josh; Hodum, Peter; Beck, Jessie; Colodro, Valentina; Vega, Rodrigo; González, Andrés

2016-01-01

The Pink-footed Shearwater, Ardenna creatopus, is listed as in danger of extinction by Chile and under Annex 1 of ACAP, with an estimated global population of approximately 56,000 individuals. Incidental bycatch of this species in fisheries is thought to be an important cause in population decline (i.e. annual estimated mortality of >1000 adults). This species is an endemic breeder in Chile, nesting only on the Juan Fernandez Archipelago (JFI; 30% of global population), and Isla Mocha (70% of global population). Using miniature GPS and satellite transmitters, we determined foraging areas of Pink-footed Shearwaters during the chick-rearing period in 2002 (JFI) and 2015-2016 (Isla Mocha). We overlaid shearwater tracking data with data from the Instituto de Fomento Pesquero (IFOP) on fishing effort in Chile (type of fishery, number sets per day, location of sets, and target species) to identify fisheries and fishing zones with the greatest potential for Pink-footed Shearwater bycatch. During the 2002-2006 (N = 28 birds total) and 2015 (N = 18 birds) breeding periods, foraging areas were associated with the continental shelf and shelf-break, generally less than 30 km offshore. All foraging trips occurred between 31.5 and 40.0 degrees south, and birds remained in Chile territorial waters 100% of the time. We identified two primary foraging hotspots, one offshore near Talcahuano, Chile (approximately 36-37.5° south), and one offshore north of Valdivia, Chile (approximately 39-39.5° south). Birds tracked from the Juan Fernández Archipelago foraged in the Talcahuano hotspot but did not visit the southerly hotspot near Valdivia. Birds tracked from Isla Mocha used both areas, with a greater proportion of birds using the Valdivia hotspot than the Talcahuano hotspot. Other major areas of use were around the respective breeding colonies from which the birds were tracked. Overlay of these data with fisheries data is currently in progress. Preliminary results indicate extensive overlap of Pink-footed Shearwater foraging grounds with industrial and artisanal purse-seine fisheries within Chile, representing a significant risk of bycatch. Further work could be initiated to track Pink-footed Shearwaters during other life-stages (i.e. pre-breeding and incubation), and would enhance collaborative efforts with fisheries managers and fishers concerned with mitigating bycatch.

The foraging benefits of being fat in a highly migratory marine mammal.

PubMed

Adachi, Taiki; Maresh, Jennifer L; Robinson, Patrick W; Peterson, Sarah H; Costa, Daniel P; Naito, Yasuhiko; Watanabe, Yuuki Y; Takahashi, Akinori

2014-12-22

Foraging theory predicts that breath-hold divers adjust the time spent foraging at depth relative to the energetic cost of swimming, which varies with buoyancy (body density). However, the buoyancy of diving animals varies as a function of their body condition, and the effects of these changes on swimming costs and foraging behaviour have been poorly examined. A novel animal-borne accelerometer was developed that recorded the number of flipper strokes, which allowed us to monitor the number of strokes per metre swam (hereafter, referred to as strokes-per-metre) by female northern elephant seals over their months-long, oceanic foraging migrations. As negatively buoyant seals increased their fat stores and buoyancy, the strokes-per-metre increased slightly in the buoyancy-aided direction (descending), but decreased significantly in the buoyancy-hindered direction (ascending), with associated changes in swim speed and gliding duration. Overall, the round-trip strokes-per-metre decreased and reached a minimum value when seals achieved neutral buoyancy. Consistent with foraging theory, seals stayed longer at foraging depths when their round-trip strokes-per-metre was less. Therefore, neutrally buoyant divers gained an energetic advantage via reduced swimming costs, which resulted in an increase in time spent foraging at depth, suggesting a foraging benefit of being fat. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Seasonal regulation of condensed tannin consumption by free-ranging goats in a semi-arid savanna

PubMed Central

Heitkӧnig, Ignas M. A.; Scogings, Peter F.; Hattas, Dawood; Dziba, Luthando E.; Prins, Herbert H. T.; de Boer, Willem F.

2018-01-01

Although condensed tannins (CTs) are known to reduce forage intake by mammalian herbivores in controlled experiments, few studies have tested these effects in the field. Thus the role of CTs on foraging ecology of free-ranging herbivores is inadequately understood. To investigate the effects of CTs under natural savanna conditions, we pre-dosed groups of goats with polyethylene glycol (PEG, a CT-neutralising chemical), CT powder or water before observing their foraging behaviour. While accounting for the effects of season and time of the day, we tested the hypothesis that herbivores forage in ways that reduce the intake rate (g DM per minute) of CTs. We expected pre-dosing goats with CTs to reduce CT intake rates by (1) consuming diets low in CTs, (2) reducing bite rates, (3) increasing the number of foraging bouts, or (4) reducing the length of foraging bouts. Lastly, (5) expected CT to have no influence the number of dietary forage species. In both wet and dry seasons, pre-dosing goats with CTs resulted in lower CT consumption rates compared to PEG goats which seemed relieved from the stress associated with CT consumption. During dry season, the number of dietary forage species was similar across treatments, although goats that were dosed with PEG significantly increased this number in the wet season. Dosing goats with PEG increased the number and length of browsing bouts compared to goats from the other treatments. Pre-loading goats with PEG also tended to increase bite rates on browse forages, which contributed to increased consumption rates of CTs. Based on the behavioural adjustments made by goats in this study and within the constraints imposed by chemical complexity in savanna systems, we concluded that herbivores under natural conditions foraged in ways that minimised CTs consumption. More research should further elucidate the mechanism through which CTs regulated feeding behaviour. PMID:29293513

Sex differences in giraffe foraging behavior at two spatial scales.

PubMed

Ginnett, T F; Demment, Montague W

1997-04-01

We test predictions about differences in the foraging behaviors of male and female giraffes (Giraffa camelopardalis tippelskirchi Matchie) that derive from a hypothesis linking sexual size dimorphism to foraging behavior. This body-size hypothesis predicts that males will exhibit specific behaviors that increase their dry-matter intake rate relative to females. Foraging behavior was examined at two hierarchical levels corresponding to two spatial and temporal scales, within patches and within habitats. Patches are defined as individual trees or shrubs and habitats are defined as collections of patches within plant communities. Males were predicted to increase dry-matter intake rate within patches by taking larger bites, cropping bites more quickly, chewing less, and chewing faster. Within habitats, males were expected to increase intake rate by increasing the proportion of foraging time devoted to food ingestion as opposed to inter-patch travel time and vigilance. The predictions were tested in a free-ranging population of giraffes in Mikumi National Park, Tanzania. Males spent less total time foraging than females but allocated a greater proportion of their foraging time to forage ingestion as opposed to travel between patches. There was no sex difference in rumination time but males spent more time in activities other than foraging and rumination, such as walking. Within patches, males took larger bites than females, but females cropped bites more quickly and chewed faster. Males had longer per-bite handling times than females but had shorter handling times per gram of intake. Within habitats, males had longer average patch residence times but there was no significant sex difference in inter-patch travel times. There was no overall difference between sexes in vigilance while foraging, although there were significant sex by habitat and sex by season interactions. Although not all the predictions were confirmed, overall the results agree qualitatively with the body-size hypothesis. Sex-related differences in foraging behavior led to greater estimated intake rates for males at the within-patch and within-habitat scales.

Long foraging distances impose high costs on offspring production in solitary bees.

PubMed

Zurbuchen, Antonia; Cheesman, Stephanie; Klaiber, Jeannine; Müller, Andreas; Hein, Silke; Dorn, Silvia

2010-05-01

1. Solitary bees are central place foragers returning to their nests several times a day with pollen and nectar to provision their brood cells. They are especially susceptible to landscape changes that lead to an increased spatial separation of suitable nesting sites and flower rich host plant stands. While knowledge of bee foraging ranges is currently growing, quantitative data on the costs of foraging flights are very scarce, although such data are crucial to understand bee population dynamics. 2. In this study, the impact of increased foraging distance on the duration of foraging bouts and on the number of brood cells provisioned per time unit was experimentally quantified in the two pollen specialist solitary bee species Hoplitis adunca and Chelostoma rapunculi. Females nesting at different sites foraged under the same environmental conditions on a single large and movable flowering host plant patch in an otherwise host plant free landscape. 3. The number of brood cells provisioned per time unit by H. adunca was found to decrease by 23%, 31% and 26% with an increase in the foraging distance by 150, 200 and 300 m, respectively. The number of brood cells provisioned by C. rapunculi decreased by 46% and 36% with an increase in the foraging distance by 500 and 600 m, respectively. 4. Contrary to expectation, a widely scattered arrangement of host plants did not result in longer mean duration of a foraging bout in H. adunca compared to a highly aggregated arrangement, which might be due to a reduced flight directionality combined with a high rate of revisitation of already depleted flowers in the aggregated plant arrangement or by a stronger competition and disturbance by other flower visitors. 5. The results of this study clearly indicate that a close neighbourhood of suitable nesting and foraging habitats is crucial for population persistence and thus conservation of endangered solitary bee species.

Forage yield, weed suppression and fertilizer nitrogen replacement value (FNRV) of alfalfa-tall fescue mixtures

USDA-ARS?s Scientific Manuscript database

Adding plant diversity to forage systems may help growers deal with increasing fertilizer costs and a more variable climate. Maintaining highly diverse forage mixtures in forage-livestock production is difficult and may warrant a closer reexamination of simpler grass-legume mixtures to achieve simi...

Genetics of postweaning performance of beef cattle on forage

USDA-ARS?s Scientific Manuscript database

Increases in the costs of feed grains have revived interest in increasing the use of forages and grazing in order to either market as forage-finished beef or to produce heavy calves that will finish on less grain. However, little is known about the interactions of animal genetics and grazing enviro...

Elevated CO2 induces substantial and persistent declines in forage quality irrespective of warming in mixedgrass prairie.

PubMed

Augustine, David J; Blumenthal, Dana M; Springer, Tim L; LeCain, Daniel R; Gunter, Stacey A; Derner, Justin D

2018-04-01

Increasing atmospheric [CO 2 ] and temperature are expected to affect the productivity, species composition, biogeochemistry, and therefore the quantity and quality of forage available to herbivores in rangeland ecosystems. Both elevated CO 2 (eCO 2 ) and warming affect plant tissue chemistry through multiple direct and indirect pathways, such that the cumulative outcomes of these effects are difficult to predict. Here, we report on a 7-yr study examining effects of CO 2 enrichment (to 600 ppm) and infrared warming (+1.5°C day/3°C night) under realistic field conditions on forage quality and quantity in a semiarid, mixedgrass prairie. For the three dominant forage grasses, warming effects on in vitro dry matter digestibility (IVDMD) and tissue [N] were detected only in certain years, varied from negative to positive, and were relatively minor. In contrast, eCO 2 substantially reduced IVDMD (two most abundant grasses) and [N] (all three dominant grass species) in most years, except the two wettest years. Furthermore, eCO 2 reduced IVDMD and [N] independent of warming effects. Reduced IVDMD with eCO 2 was related both to reduced [N] and increased acid detergent fiber (ADF) content of grass tissues. For the six most abundant forage species (representing 96% of total forage production), combined warming and eCO 2 increased forage production by 38% and reduced forage [N] by 13% relative to ambient climate. Although the absolute magnitude of the decline in IVDMD and [N] due to combined warming and eCO 2 may seem small (e.g., from 63.3 to 61.1% IVDMD and 1.25 to 1.04% [N] for Pascopyrum smithii), such shifts could have substantial consequences for the rate at which ruminants gain weight during the primary growing season in the largest remaining rangeland ecosystem in North America. With forage production increases, declining forage quality could potentially be mitigated by adaptively increasing stocking rates, and through management such as prescribed burning, fertilization at low rates, and legume interseeding to enhance forage quality. © 2018 by the Ecological Society of America.

Group foraging by a stream minnow: shoals or aggregations?

USGS Publications Warehouse

Freeman, Mary C.; Grossman, G.D.

1992-01-01

The importance of social attraction in the formation of foraging groups was examined for a stream-dwelling cyprinid, the rosyside dace, Clinostomus funduloides. Dace arrivals and departures at natural foraging sites were monitored and tested for (1) tendency of dace to travel in groups, and (2) dependency of arrival and departure rates on group size. Dace usually entered and departed foraging sites independently of each other. Group size usually affected neither arrival rate nor departure probability. Thus, attraction among dace appeared weak; foraging groups most often resulted from dace aggregating in preferred foraging sites. The strongest evidence of social attraction was during autumn, when dace departure probability often decreased with increasing group size, possibly in response to increased threat of predation by a seasonally occurring predator. Dace also rarely avoided conspecifics, except when an aggressive individual defended a foraging site. Otherwise, there was little evidence of exploitative competition among dace for drifting prey or of foraging benefits in groups, because group size usually did not affect individual feeding rates. These results suggest that the benefits of group foraging demonstrated under laboratory conditions in other studies may not always apply to field conditions.

Estimating yields of salt- and water-stressed forages with remote sensing in the visible and near infrared.

PubMed

Poss, J A; Russell, W B; Grieve, C M

2006-01-01

In arid irrigated regions, the proportion of crop production under deficit irrigation with poorer quality water is increasing as demand for fresh water soars and efforts to prevent saline water table development occur. Remote sensing technology to quantify salinity and water stress effects on forage yield can be an important tool to address yield loss potential when deficit irrigating with poor water quality. Two important forages, alfalfa (Medicago sativa L.) and tall wheatgrass (Agropyron elongatum L.), were grown in a volumetric lysimeter facility where rootzone salinity and water content were varied and monitored. Ground-based hyperspectral canopy reflectance in the visible and near infrared (NIR) were related to forage yields from a broad range of salinity and water stress conditions. Canopy reflectance spectra were obtained in the 350- to 1000-nm region from two viewing angles (nadir view, 45 degrees from nadir). Nadir view vegetation indices (VI) were not as strongly correlated with leaf area index changes attributed to water and salinity stress treatments for both alfalfa and wheatgrass. From a list of 71 VIs, two were selected for a multiple linear-regression model that estimated yield under varying salinity and water stress conditions. With data obtained during the second harvest of a three-harvest 100-d growing period, regression coefficients for each crop were developed and then used with the model to estimate fresh weights for preceding and succeeding harvests during the same 100-d interval. The model accounted for 72% of the variation in yields in wheatgrass and 94% in yields of alfalfa within the same salinity and water stress treatment period. The model successfully predicted yield in three out of four cases when applied to the first and third harvest yields. Correlations between indices and yield increased as canopy development progressed. Growth reductions attributed to simultaneous salinity and water stress were well characterized, but the corrections for effects of varying tissue nitrogen (N) and very low leaf area index (LAI) are necessary.

Dance communication affects consistency, but not breadth, of resource use in pollen-foraging honey bees.

PubMed

Donaldson-Matasci, Matina; Dornhaus, Anna

2014-01-01

In groups of cooperatively foraging individuals, communication may improve the group's performance by directing foraging effort to where it is most useful. Honey bees (Apis mellifera) use a specialized dance to communicate the location of floral resources. Because honey bees dance longer for more rewarding resources, communication may shift the colony's foraging effort towards higher quality resources, and thus narrow the spectrum of resource types used. To test the hypothesis that dance communication changes how much honey bee colonies specialize on particular resources, we manipulated their ability to communicate location, and assessed the relative abundance of different pollen taxa they collected. This was repeated across five natural habitats that differed in floral species richness and spatial distribution. Contrary to expectation, impairing communication did not change the number or diversity of pollen (resource) types used by individual colonies per day. However, colonies with intact dance communication were more consistent in their resource use, while those with impaired communication were more likely to collect rare, novel pollen types. This suggests that communication plays an important role in shaping how much colonies invest in exploring new resources versus exploiting known ones. Furthermore, colonies that did more exploration also tended to collect less pollen overall, but only in environments with greater floral abundance per patch. In such environments, the ability to effectively exploit highly rewarding resources may be especially important-and dance communication may help colonies do just that. This could help explain how communication benefits honey bee colonies, and also why it does so only under certain environmental conditions.

Dance Communication Affects Consistency, but Not Breadth, of Resource Use in Pollen-Foraging Honey Bees

PubMed Central

Donaldson-Matasci, Matina; Dornhaus, Anna

2014-01-01

In groups of cooperatively foraging individuals, communication may improve the group’s performance by directing foraging effort to where it is most useful. Honey bees (Apis mellifera) use a specialized dance to communicate the location of floral resources. Because honey bees dance longer for more rewarding resources, communication may shift the colony’s foraging effort towards higher quality resources, and thus narrow the spectrum of resource types used. To test the hypothesis that dance communication changes how much honey bee colonies specialize on particular resources, we manipulated their ability to communicate location, and assessed the relative abundance of different pollen taxa they collected. This was repeated across five natural habitats that differed in floral species richness and spatial distribution. Contrary to expectation, impairing communication did not change the number or diversity of pollen (resource) types used by individual colonies per day. However, colonies with intact dance communication were more consistent in their resource use, while those with impaired communication were more likely to collect rare, novel pollen types. This suggests that communication plays an important role in shaping how much colonies invest in exploring new resources versus exploiting known ones. Furthermore, colonies that did more exploration also tended to collect less pollen overall, but only in environments with greater floral abundance per patch. In such environments, the ability to effectively exploit highly rewarding resources may be especially important–and dance communication may help colonies do just that. This could help explain how communication benefits honey bee colonies, and also why it does so only under certain environmental conditions. PMID:25271418

Increased plastic litter cover affects the foraging activity of the sandy intertidal gastropod Nassarius pullus.

PubMed

Aloy, Alexander B; Vallejo, Benjamin M; Juinio-Meñez, Marie Antonette

2011-08-01

This study analyzed the foraging behavior of the gastropod Nassarius pullus on garbage-impacted sandy shores of Talim Bay, Batangas, Philippines. The effect of different levels of plastic garbage cover on foraging efficiency was investigated. Controlled in situ baiting experiments were conducted to quantify aspects of foraging behavior as affected by the levels of plastic litter cover in the foraging area. The results of the study indicated that the gastropod's efficiency in locating and in moving towards a food item generally decreased as the level of plastic cover increased. Prolonged food searching time and increased self-burial in sand were highly correlated with increased plastic cover. The accuracy of orientation towards the actual position of the bait decreased significantly when the amount of plastic cover increased to 50%. These results are consistent with the significant decreases in the abundance of the gastropod observed during periods of deposition of large amounts of plastic and other debris on the shore. Copyright © 2011 Elsevier Ltd. All rights reserved.

Net effects of nitrogen fertilization on the nutritive value and digestibility of oat forages

USDA-ARS?s Scientific Manuscript database

Applications of soil amendments containing N are part of routine forage management strategies for grasses, with a primary goal of increasing forage yield. However, the effects of N fertilization on forage nutritive value, estimates of energy density, and in-vitro DM or NDF disappearance often have b...

Contrafreeloading in grizzly bears: implications for captive foraging enrichment.

PubMed

McGowan, Ragen T S; Robbins, Charles T; Alldredge, J Richard; Newberry, Ruth C

2010-01-01

Although traditional feeding regimens for captive animals were focused on meeting physiological needs to assure good health, more recently emphasis has also been placed on non-nutritive aspects of feeding. The provision of foraging materials to diversify feeding behavior is a common practice in zoos but selective consumption of foraging enrichment items over more balanced "chow" diets could lead to nutrient imbalance. One alternative is to provide balanced diets in a contrafreeloading paradigm. Contrafreeloading occurs when animals choose resources that require effort to exploit when identical resources are freely available. To investigate contrafreeloading and its potential as a theoretical foundation for foraging enrichment, we conducted two experiments with captive grizzly bears (Ursus arctos horribilis). In Experiment 1, bears were presented with five foraging choices simultaneously: apples, apples in ice, salmon, salmon in ice, and plain ice under two levels of food restriction. Two measures of contrafreeloading were considered: weight of earned food consumed and time spent working for earned food. More free than earned food was eaten, with only two bears consuming food extracted from ice, but all bears spent more time manipulating ice containing salmon or apples than plain ice regardless of level of food restriction. In Experiment 2, food-restricted bears were presented with three foraging choices simultaneously: apples, apples inside a box, and an empty box. Although they ate more free than earned food, five bears consumed food from boxes and all spent more time manipulating boxes containing apples than empty boxes. Our findings support the provision of contrafreeloading opportunities as a foraging enrichment strategy for captive wildlife. (c) 2009 Wiley-Liss, Inc.

Quasi-planktonic behavior of foraging top marine predators

NASA Astrophysics Data System (ADS)

Della Penna, Alice; de Monte, Silvia; Kestenare, Elodie; Guinet, Christophe; D'Ovidio, Francesco

2015-12-01

Monitoring marine top predators is fundamental for assessing the health and functioning of open ocean ecosystems. Although recently tracking observations have substantially increased, factors determining the horizontal exploration of the ocean by marine predators are still largely unknown, especially at the scale of behavioral switches (1-100 km, days-weeks). It is commonly assumed that the influence of water movement can be neglected for animals capable of swimming faster than the current. Here, we challenge this assumption by combining the use of biologging (GPS and accelerometry), satellite altimetry and in-situ oceanographic data (ADCP and drifting buoys) to investigate the effect of the mesoscale ocean dynamics on a marine predator, the southern elephant seal. A Lagrangian approach reveals that trajectories of elephant seals are characterized by quasi-planktonic bouts where the animals are horizontally drifting. These bouts correspond to periods of increased foraging effort, indicating that in the quasi-planktonic conditions energy is allocated to diving and chasing, rather than in horizontal search of favourable grounds. These results suggest that mesoscale features like eddies and fronts may act as a focal points for trophic interactions not only by bottom-up modulation of nutrient injection, but also by directly entraining horizontal displacements of the upper trophic levels.

Quasi-planktonic behavior of foraging top marine predators.

PubMed

Della Penna, Alice; De Monte, Silvia; Kestenare, Elodie; Guinet, Christophe; d'Ovidio, Francesco

2015-12-15

Monitoring marine top predators is fundamental for assessing the health and functioning of open ocean ecosystems. Although recently tracking observations have substantially increased, factors determining the horizontal exploration of the ocean by marine predators are still largely unknown, especially at the scale of behavioral switches (1-100 km, days-weeks). It is commonly assumed that the influence of water movement can be neglected for animals capable of swimming faster than the current. Here, we challenge this assumption by combining the use of biologging (GPS and accelerometry), satellite altimetry and in-situ oceanographic data (ADCP and drifting buoys) to investigate the effect of the mesoscale ocean dynamics on a marine predator, the southern elephant seal. A Lagrangian approach reveals that trajectories of elephant seals are characterized by quasi-planktonic bouts where the animals are horizontally drifting. These bouts correspond to periods of increased foraging effort, indicating that in the quasi-planktonic conditions energy is allocated to diving and chasing, rather than in horizontal search of favourable grounds. These results suggest that mesoscale features like eddies and fronts may act as a focal points for trophic interactions not only by bottom-up modulation of nutrient injection, but also by directly entraining horizontal displacements of the upper trophic levels.

In search of annual legumes to improve forage sorghum yield and nutritive value in the southern high plains

USDA-ARS?s Scientific Manuscript database

Livestock production is significant in the Southern High Plains of the USA and demand is increasing for greater forage dry matter (DM) yield with increased nutritive value. Forage sorghum (FS)[Sorghum bicolor (L.) Moench] is commonly used, although, it is low in crude protein (CP) and high in fiber....

A properly adjusted forage harvester can save time and money

USDA-ARS?s Scientific Manuscript database

A properly adjusted forage harvester can save fuel and increase the realizable milk per ton of your silage. This article details the adjustments necessary to minimize energy while maximizing productivity and forage quality....

Multiple-stage decisions in a marine central-place forager

NASA Astrophysics Data System (ADS)

Friedlaender, Ari S.; Johnston, David W.; Tyson, Reny B.; Kaltenberg, Amanda; Goldbogen, Jeremy A.; Stimpert, Alison K.; Curtice, Corrie; Hazen, Elliott L.; Halpin, Patrick N.; Read, Andrew J.; Nowacek, Douglas P.

2016-05-01

Air-breathing marine animals face a complex set of physical challenges associated with diving that affect the decisions of how to optimize feeding. Baleen whales (Mysticeti) have evolved bulk-filter feeding mechanisms to efficiently feed on dense prey patches. Baleen whales are central place foragers where oxygen at the surface represents the central place and depth acts as the distance to prey. Although hypothesized that baleen whales will target the densest prey patches anywhere in the water column, how depth and density interact to influence foraging behaviour is poorly understood. We used multi-sensor archival tags and active acoustics to quantify Antarctic humpback whale foraging behaviour relative to prey. Our analyses reveal multi-stage foraging decisions driven by both krill depth and density. During daylight hours when whales did not feed, krill were found in deep high-density patches. As krill migrated vertically into larger and less dense patches near the surface, whales began to forage. During foraging bouts, we found that feeding rates (number of feeding lunges per hour) were greatest when prey was shallowest, and feeding rates decreased with increasing dive depth. This strategy is consistent with previous models of how air-breathing diving animals optimize foraging efficiency. Thus, humpback whales forage mainly when prey is more broadly distributed and shallower, presumably to minimize diving and searching costs and to increase feeding rates overall and thus foraging efficiency. Using direct measurements of feeding behaviour from animal-borne tags and prey availability from echosounders, our study demonstrates a multi-stage foraging process in a central place forager that we suggest acts to optimize overall efficiency by maximizing net energy gain over time. These data reveal a previously unrecognized level of complexity in predator-prey interactions and underscores the need to simultaneously measure prey distribution in marine central place forager studies.

Food limitation of sea lion pups and the decline of forage off central and southern California

PubMed Central

McClatchie, Sam; Field, John; Thompson, Andrew R.; Gerrodette, Tim; Lowry, Mark; Fiedler, Paul C.; Watson, William; Nieto, Karen M.; Vetter, Russell D.

2016-01-01

California sea lions increased from approximately 50 000 to 340 000 animals in the last 40 years, and their pups are starving and stranding on beaches in southern California, raising questions about the adequacy of their food supply. We investigated whether the declining sea lion pup weight at San Miguel rookery was associated with changes in abundance and quality of sardine, anchovy, rockfish and market squid forage. In the last decade off central California, where breeding female sea lions from San Miguel rookery feed, sardine and anchovy greatly decreased in biomass, whereas market squid and rockfish abundance increased. Pup weights fell as forage food quality declined associated with changes in the relative abundances of forage species. A model explained 67% of the variance in pup weights using forage from central and southern California and 81% of the variance in pup weights using forage from the female sea lion foraging range. A shift from high to poor quality forage for breeding females results in food limitation of the pups, ultimately flooding animal rescue centres with starving sea lion pups. Our study is unusual in using a long-term, fishery-independent dataset to directly address an important consequence of forage decline on the productivity of a large marine predator. Whether forage declines are environmentally driven, are due to a combination of environmental drivers and fishing removals, or are due to density-dependent interactions between forage and sea lions is uncertain. However, declining forage abundance and quality was coherent over a large area (32.5–38° N) for a decade, suggesting that trends in forage are environmentally driven. PMID:27069651

Multiple-stage decisions in a marine central-place forager.

PubMed

Friedlaender, Ari S; Johnston, David W; Tyson, Reny B; Kaltenberg, Amanda; Goldbogen, Jeremy A; Stimpert, Alison K; Curtice, Corrie; Hazen, Elliott L; Halpin, Patrick N; Read, Andrew J; Nowacek, Douglas P

2016-05-01

Air-breathing marine animals face a complex set of physical challenges associated with diving that affect the decisions of how to optimize feeding. Baleen whales (Mysticeti) have evolved bulk-filter feeding mechanisms to efficiently feed on dense prey patches. Baleen whales are central place foragers where oxygen at the surface represents the central place and depth acts as the distance to prey. Although hypothesized that baleen whales will target the densest prey patches anywhere in the water column, how depth and density interact to influence foraging behaviour is poorly understood. We used multi-sensor archival tags and active acoustics to quantify Antarctic humpback whale foraging behaviour relative to prey. Our analyses reveal multi-stage foraging decisions driven by both krill depth and density. During daylight hours when whales did not feed, krill were found in deep high-density patches. As krill migrated vertically into larger and less dense patches near the surface, whales began to forage. During foraging bouts, we found that feeding rates (number of feeding lunges per hour) were greatest when prey was shallowest, and feeding rates decreased with increasing dive depth. This strategy is consistent with previous models of how air-breathing diving animals optimize foraging efficiency. Thus, humpback whales forage mainly when prey is more broadly distributed and shallower, presumably to minimize diving and searching costs and to increase feeding rates overall and thus foraging efficiency. Using direct measurements of feeding behaviour from animal-borne tags and prey availability from echosounders, our study demonstrates a multi-stage foraging process in a central place forager that we suggest acts to optimize overall efficiency by maximizing net energy gain over time. These data reveal a previously unrecognized level of complexity in predator-prey interactions and underscores the need to simultaneously measure prey distribution in marine central place forager studies.

Coastal leatherback turtles reveal conservation hotspot

PubMed Central

Robinson, Nathan J.; Morreale, Stephen J.; Nel, Ronel; Paladino, Frank V.

2016-01-01

Previous studies have shown that the world’s largest reptile – the leatherback turtle Dermochelys coriacea – conducts flexible foraging migrations that can cover thousands of kilometres between nesting sites and distant foraging areas. The vast distances that may be travelled by migrating leatherback turtles have greatly complicated conservation efforts for this species worldwide. However, we demonstrate, using a combination of satellite telemetry and stable isotope analysis, that approximately half of the nesting leatherbacks from an important rookery in South Africa do not migrate to distant foraging areas, but rather, forage in the coastal waters of the nearby Mozambique Channel. Moreover, this coastal cohort appears to remain resident year-round in shallow waters (<50 m depth) in a relatively fixed area. Stable isotope analyses further indicate that the Mozambique Channel also hosts large numbers of loggerhead turtles Caretta caretta. The rare presence of a resident coastal aggregation of leatherback turtles not only presents a unique opportunity for conservation, but alongside the presence of loggerhead turtles and other endangered marine megafauna in the Mozambique Channel, highlights the importance of this area as a marine biodiversity hotspot. PMID:27886262

Subglacial discharges create fluctuating foraging hotspots for sea birds in tidewater glacier bays

PubMed Central

Urbanski, Jacek Andrzej; Stempniewicz, Lech; Węsławski, Jan Marcin; Dragańska-Deja, Katarzyna; Wochna, Agnieszka; Goc, Michał; Iliszko, Lech

2017-01-01

Although the processes occurring at the front of an ice face in tidewater glacier bays still await thorough investigation, their importance to the rapidly changing polar environment is spurring a considerable research effort. Glacier melting, sediment delivery and the formation of seabird foraging hotspots are governed by subglacial discharges of meltwater. We have combined the results of tracking black-legged kittiwakes Rissa tridactyla equipped with GPS loggers, analyses of satellite images and in situ measurements of water temperature, salinity and turbidity in order to examine the magnitude and variability of such hotspots in the context of glacier bay hydrology. Small though these hotspots are in size, foraging in them appears to be highly intensive. They come into existence only if the subglacial discharge reaches the surface, if the entrainment velocity at a conduit is high and if there is sufficient macroplankton in the entrainment layer. The position and type of subglacial discharges may fluctuate in time and space, thereby influencing glacier bay hydrology and the occurrence of foraging hotspots. PMID:28266602

Human memory retrieval as Lévy foraging

NASA Astrophysics Data System (ADS)

Rhodes, Theo; Turvey, Michael T.

2007-11-01

When people attempt to recall as many words as possible from a specific category (e.g., animal names) their retrievals occur sporadically over an extended temporal period. Retrievals decline as recall progresses, but short retrieval bursts can occur even after tens of minutes of performing the task. To date, efforts to gain insight into the nature of retrieval from this fundamental phenomenon of semantic memory have focused primarily upon the exponential growth rate of cumulative recall. Here we focus upon the time intervals between retrievals. We expected and found that, for each participant in our experiment, these intervals conformed to a Lévy distribution suggesting that the Lévy flight dynamics that characterize foraging behavior may also characterize retrieval from semantic memory. The closer the exponent on the inverse square power-law distribution of retrieval intervals approximated the optimal foraging value of 2, the more efficient was the retrieval. At an abstract dynamical level, foraging for particular foods in one's niche and searching for particular words in one's memory must be similar processes if particular foods and particular words are randomly and sparsely located in their respective spaces at sites that are not known a priori. We discuss whether Lévy dynamics imply that memory processes, like foraging, are optimized in an ecological way.

A Breath of Fresh Air in Foraging Theory: The Importance of Wind for Food Size Selection in a Central-Place Forager.

PubMed

Alma, Andrea Marina; Farji-Brener, Alejandro G; Elizalde, Luciana

2017-09-01

Empirical data about food size carried by central-place foragers do not often fit with the optimum predicted by classical foraging theory. Traditionally, biotic constraints such as predation risk and competition have been proposed to explain this inconsistency, leaving aside the possible role of abiotic factors. Here we documented how wind affects the load size of a central-place forager (leaf-cutting ants) through a mathematical model including the whole foraging process. The model showed that as wind speed at ground level increased from 0 to 2 km/h, load size decreased from 91 to 30 mm 2 , a prediction that agreed with empirical data from windy zones, highlighting the relevance of considering abiotic factors to predict foraging behavior. Furthermore, wind reduced the range of load sizes that workers should select to maintain a similar rate of food intake and decreased the foraging rate by ∼70% when wind speed increased 1 km/h. These results suggest that wind could reduce the fitness of colonies and limit the geographic distribution of leaf-cutting ants. The developed model offers a complementary explanation for why load size in central-place foragers may not fit theoretical predictions and could serve as a basis to study the effects of other abiotic factors that influence foraging.

The implications of condensed tannins on the nutritive value of temperate forages fed to ruminants.

PubMed

Barry, T N; McNabb, W C

1999-04-01

New methodology for measuring forage condensed tannin (CT) content is described and the effects of CT upon forage feeding and nutritive value for ruminant animals are reviewed. CT react with forage proteins in a pH-reversible manner, with reactivity determined by the concentration, structure and molecular mass of the CT. Increasing concentrations of CT in Lotus corniculatus and Lotus pedunculatus reduce the rates of solubilization and degradation of fraction 1 leaf protein in the rumen and increase duodenal non-NH3 N flow. Action of medium concentrations of total CT in Lotus corniculatus (30-40 g/kg DM) increased the absorption of essential amino acids from the small intestine and increased wool growth, milk secretion and reproductive rate in grazing sheep without affecting voluntary feed intake, thus improving the efficiency of food conversion. High concentrations of CT in Lotus pedunculatus (75-100 g/kg DM) depressed voluntary feed intake and rumen carbohydrate digestion and depressed rates of body and wool growth in grazing sheep. The minimum concentration of CT to prevent rumen frothy bloat in cattle is defined as 5 g/kg DM and sheep grazing CT-containing legumes were shown to better tolerate internal parasite infections than sheep grazing non CT-containing forages. It was concluded that defined concentrations of forage CT can be used to increase the efficiencies of protein digestion and animal productivity in forage-fed ruminants and to develop more ecologically sustainable systems of controlling some diseases under grazing.

Bioinformatics in the orphan crops.

PubMed

Armstead, Ian; Huang, Lin; Ravagnani, Adriana; Robson, Paul; Ougham, Helen

2009-11-01

Orphan crops are those which are grown as food, animal feed or other crops of some importance in agriculture, but which have not yet received the investment of research effort or funding required to develop significant public bioinformatics resources. Where an orphan crop is related to a well-characterised model plant species, comparative genomics and bioinformatics can often, though not always, be exploited to assist research and crop improvement. This review addresses some challenges and opportunities presented by bioinformatics in the orphan crops, using three examples: forage grasses from the genera Lolium and Festuca, forage legumes and the second generation energy crop Miscanthus.

Stingless bees (Melipona scutellaris) learn to associate footprint cues at food sources with a specific reward context.

PubMed

Roselino, Ana Carolina; Rodrigues, André Vieira; Hrncir, Michael

2016-10-01

Foraging insects leave chemical footprints on flowers that subsequent foragers may use as indicators for recent flower visits and, thus, potential resource depletion. Accordingly, foragers should reject food sources presenting these chemical cues. Contrasting this assumption, experimental studies in stingless bees (Apidae, Meliponini), so far, demonstrated an attractive effect of footprints. These findings lead to doubts about the meaning of these chemical cues in natural foraging contexts. Here, we asked whether foragers of stingless bees (Melipona scutellaris) use footprints according to the previously experienced reward level of visited food sources. Bees were trained to artificial flower patches, at which the reward of a flower either decreased or, alternatively, increased after a visit by a forager. Individuals were allowed a total of nine foraging bouts to the patch, after which their preference for visited or unvisited flowers was tested. In the choice tests, bees trained under the decreasing reward context preferred unvisited flowers, whereas individuals trained under the increasing reward context preferred visited flowers. Foragers without experience chose randomly between visited and unvisited flowers. These results demonstrate that M. scutellaris learns to associate unspecific footprint cues at food sources with differential, specific reward contexts, and uses these chemical cues accordingly for their foraging decisions.

Apparent changes in body insulation of juvenile king penguins suggest an energetic challenge during their early life at sea.

PubMed

Enstipp, Manfred R; Bost, Charles-André; Le Bohec, Céline; Bost, Caroline; Le Maho, Yvon; Weimerskirch, Henri; Handrich, Yves

2017-07-15

Little is known about the early life at sea of marine top predators, like deep-diving king penguins ( Aptenodytes patagonicus ), although this dispersal phase is probably a critical phase in their life. Apart from finding favourable foraging sites, they have to develop effective prey search patterns as well as physiological capacities that enable them to capture sufficient prey to meet their energetic needs. To investigate the ontogeny of their thermoregulatory responses at sea, we implanted 30 juvenile king penguins and 8 adult breeders with a small data logger that recorded pressure and subcutaneous temperature continuously for up to 2.5 years. We found important changes in the development of peripheral temperature patterns of foraging juvenile king penguins throughout their first year at sea. Peripheral temperature during foraging bouts fell to increasingly lower levels during the first 6 months at sea, after which it stabilized. Most importantly, these changes re-occurred during their second year at sea, after birds had fasted for ∼4 weeks on land during their second moult. Furthermore, similar peripheral temperature patterns were also present in adult birds during foraging trips throughout their breeding cycle. We suggest that rather than being a simple consequence of concurrent changes in dive effort or an indication of a physiological maturation process, these seasonal temperature changes mainly reflect differences in thermal insulation. Heat loss estimates for juveniles at sea were initially high but declined to approximately half after ∼6 months at sea, suggesting that juvenile king penguins face a strong energetic challenge during their early oceanic existence. © 2017. Published by The Company of Biologists Ltd.

Central-place foraging and ecological effects of an invasive predator across multiple habitats.

PubMed

Benkwitt, Cassandra E

2016-10-01

Cross-habitat foraging movements of predators can have widespread implications for predator and prey populations, community structure, nutrient transfer, and ecosystem function. Although central-place foraging models and other aspects of optimal foraging theory focus on individual predator behavior, they also provide useful frameworks for understanding the effects of predators on prey populations across multiple habitats. However, few studies have examined both the foraging behavior and ecological effects of nonnative predators across multiple habitats, and none has tested whether nonnative predators deplete prey in a manner predicted by these foraging models. I conducted behavioral observations of invasive lionfish (Pterois volitans) to determine whether they exhibit foraging movements similar to other central-place consumers. Then, I used a manipulative field experiment to test whether their effects on prey populations are consistent with three qualitative predictions from optimal foraging models. Specifically, I predicted that the effects of invasive lionfish on native prey will (1) occur at central sites first and then in surrounding habitats, (2) decrease with increasing distance away from their shelter site, and (3) extend to greater distances when prey patches are spaced closer together. Approximately 40% of lionfish exhibited short-term crepuscular foraging movements into surrounding habitats from the coral patch reefs where they shelter during daylight hours. Over the course of 7 weeks, lionfish depleted native fish populations on the coral patch reefs where they reside, and subsequently on small structures in the surrounding habitat. However, their effects did not decrease with increasing distance from the central shelter site and the influence of patch spacing was opposite the prediction. Instead, lionfish always had the greatest effects in areas with the highest prey densities. The differences between the predicted and observed effects of lionfish foraging are likely due to different constraints faced by invasive predators compared to native predators, namely that lionfish do not face increased predation risk with increased movement away from shelter sites. By foraging at greater distances from patch reefs than native predators, lionfish eliminated a spatial refuge from predation used by juveniles of many commercially and ecologically important reef fishes. © 2016 by the Ecological Society of America.

Effects of corn particle size and source on performance of lactating cows fed direct-cut grass-legume forage.

PubMed

Reis, R B; Emeterio, F S; Combs, D K; Satter, L D; Costa, H N

2001-02-01

We conducted two experiments to evaluate the effects of corn supplementation, source of corn, and corn particle size on performance and nutrient utilization of lactating dairy cows. In experiment 1, treatments were 1) direct-cut grass-legume forage without supplement, 2) direct-cut forage plus 10 kg DM of ground dry shelled corn-based concentrate, and 3) direct-cut forage plus 10 kg DM of coarsely ground high moisture ear corn-based concentrate. In experiment 2, treatments were 1) direct-cut grass-legume forage plus 10 kg DM of ground dry shelled corn-based concentrate, 2) direct-cut forage plus 10 kg DM of coarsely ground high moisture ear corn-based concentrate, and 3) direct-cut forage plus 10 kg of DM finely ground high moisture ear corn-based concentrate. Both experiments were designed as 3 x 3 Latin squares replicated three times. In experiment 1, yields of milk and milk protein increased with concentrate supplementation, but were not affected by source of corn. Solids-corrected milk yield tended to increase with grain supplementation. Dry matter intake increased with concentrate supplementation, but was not affected by source of corn or corn particle size. Corn supplements decreased ruminal pH and acetate to propionate ratio and increased ruminal propionate concentration. Grain supplements reduced ruminal ammonia concentration, increased concentration of urine allantoin, and increased the urinary allantoin to creatinine ratio. In the second study, fine grinding of high moisture corn reduced fecal starch plus free glucose levels and tended to increase its apparent digestibility. In both experiments, starch plus free glucose intake was higher on the diets with dry corn, but its utilization was not affected by source of corn.

Habitat use by female caribou: Tradeoffs associated with parturition

USGS Publications Warehouse

Barten, Neil L.; Bowyer, R.T.; Jenkins, Kurt J.

2001-01-01

We compared habitat use, forage characteristics, and group size among preparturient, parturient, and nonparturient female caribou (Rangifer tarandus) during and after the birthing season to test hypotheses involving acquisition of forage and risk of predation. We monitored 39 radiocollared females from the Mentasta caribou herd, Alaska, in 1994 and 40 animals in 1995. Group size of females giving birth at higher elevations was smaller (P 0.5). During peak parturition, females with young used sites with fewer predators (P < 0.05), a lower abundance of forage (P < 0.05), but with variable forage quality compared with those sites used by females without young. We hypothesized that parturient females used birth sites that lowered risk of predation, and traded-off forage abundance for increased safety. Nonetheless, few differences existed between parturient and nonparturient females in composition of diet or in indices of diet quality; we could not demonstrate a nutritional cost to maternal females from our analyses. We suggest that increasing population density might intensify intraspecific competition among females for birth sites, and thereby increase nutritional costs of using high-elevation areas with less forage but fewer predators.

Season and landscape composition affect pollen foraging distances and habitat use of honey bees.

PubMed

Danner, Nadja; Molitor, Anna Maria; Schiele, Susanne; Härtel, Stephan; Steffan-Dewenter, Ingolf

2016-09-01

Honey bees (Apis mellifera L.) show a large variation in foraging distances and use a broad range of plant species as pollen resources, even in regions with intensive agriculture. However, it is unknown how increasing areas of mass-flowering crops like oilseed rape (Brassica napus; OSR) or a decrease of seminatural habitats (SNH) change the temporal and spatial availability of pollen resources for honey bee colonies, and thus foraging distances and frequency in different habitat types. We studied pollen foraging of honey bee colonies in 16 agricultural landscapes with independent gradients of OSR and SNH area within 2 km and used waggle dances and digital geographic maps with major land cover types to reveal the distance and visited habitat type on a landscape level. Mean pollen foraging distance of 1347 decoded bee dances was 1015 m (± 26 m; SEM). In spring, increasing area of flowering OSR within 2 km reduced mean pollen foraging distances from 1324 m to only 435 m. In summer, increasing cover of SNH areas close to the colonies (within 200 m radius) reduced mean pollen foraging distances from 846 to 469 m. Frequency of pollen foragers per habitat type, measured as the number of dances per hour and hectare, was equally high for SNH, grassland, and OSR fields, but lower for other crops and forests. In landscapes with a small proportion of SNH a significantly higher density of pollen foragers on SNH was observed, indicating that pollen resources in such simple agricultural landscapes are more limited. Overall, we conclude that SNH and mass-flowering crops can reduce foraging distances of honey bee colonies at different scales and seasons with possible benefits for the performance of honey bee colonies. Further, mixed agricultural landscapes with a high proportion of SNH reduce foraging densities of honey bees in SNH and thus possible competition for pollen resources. © 2016 by the Ecological Society of America.

Hypothermic stunning of green sea turtles in a western Gulf of Mexico foraging habitat.

PubMed

Shaver, Donna J; Tissot, Philippe E; Streich, Mary M; Walker, Jennifer Shelby; Rubio, Cynthia; Amos, Anthony F; George, Jeffrey A; Pasawicz, Michelle R

2017-01-01

Texas waters provide one of the most important developmental and foraging habitats for juvenile green turtles (Chelonia mydas) in the western Gulf of Mexico, but hypothermic stunning is a significant threat and was the largest cause of green turtle strandings in Texas from 1980 through 2015; of the 8,107 green turtles found stranded, 4,529 (55.9%) were victims of hypothermic stunning. Additionally, during this time, 203 hypothermic stunned green turtles were found incidentally captured due to power plant water intake entrapment. Overall, 63.9% of 4,529 hypothermic stunned turtles were found alive, and 92.0% of those survived rehabilitation and were released. Numbers of green turtles recorded as stranded and as affected by hypothermic stunning increased over time, and were most numerous from 2007 through 2015. Large hypothermic stunning events (with more than 450 turtles documented) occurred during the winters of 2009-2010, 2010-2011, 2013-2014, and 2014-2015. Hypothermic stunning was documented between November and March, but peaked at various times depending on passage of severe weather systems. Hypothermic stunning occurred state-wide, but was most prevalent in South Texas, particularly the Laguna Madre. In the Laguna Madre, hypothermic stunning was associated with an abrupt drop in water temperatures strong northerly winds, and a threshold mean water temperature of 8.0°C predicted large turtle hypothermic stunning events. Knowledge of environmental parameters contributing to hypothermic stunning and the temporal and spatial distribution of turtles affected in the past, can aid with formulation of proactive, targeted search and rescue efforts that can ultimately save the lives of many affected individuals, and aid with recovery efforts for this bi-national stock. Such rescue efforts are required under the U.S. Endangered Species Act and respond to humanitarian concerns of the public.

Environmental variability drives shifts in the foraging behaviour and reproductive success of an inshore seabird.

PubMed

Kowalczyk, Nicole D; Reina, Richard D; Preston, Tiana J; Chiaradia, André

2015-08-01

Marine animals forage in areas that aggregate prey to maximize their energy intake. However, these foraging 'hot spots' experience environmental variability, which can substantially alter prey availability. To survive and reproduce animals need to modify their foraging in response to these prey shifts. By monitoring their inter-annual foraging behaviours, we can understand which environmental variables affect their foraging efficiency, and can assess how they respond to environmental variability. Here, we monitored the foraging behaviour and isotopic niche of little penguins (Eudyptula minor), over 3 years (2008, 2011, and 2012) of climatic and prey variability within Port Phillip Bay, Australia. During drought (2008), penguins foraged in close proximity to the Yarra River outlet on a predominantly anchovy-based diet. In periods of heavy rainfall, when water depth in the largest tributary into the bay (Yarra River) was high, the total distance travelled, maximum distance travelled, distance to core-range, and size of core- and home-ranges of penguins increased significantly. This larger foraging range was associated with broad dietary diversity and high reproductive success. These results suggest the increased foraging range and dietary diversity of penguins were a means to maximize resource acquisition rather than a strategy to overcome local depletions in prey. Our results demonstrate the significance of the Yarra River in structuring predator-prey interactions in this enclosed bay, as well as the flexible foraging strategies of penguins in response to environmental variability. This plasticity is central to the survival of this small-ranging, resident seabird species.

Integrating research and management to conserve wildfowl (Anatidae) and wetlands in the Mississippi Alluvial Valley, U.S.A

USGS Publications Warehouse

Reinecke, K.J.; Loesch, C.R.; Birkan, Marcel

1996-01-01

Efforts to conserve winter habitat for wildfowl, Anatidae, in the alluvial valley of the lower Mississippi River, U.S.A., are directed by the Lower Mississippi Valley (LMV) Joint Venture of the North American Waterfowl Management Plan (NA WMP). The Joint Venture is based on a biological framework developed through cooperative planning by wildfowl researchers and managers. Important elements of the framework include: (1) numeric population goals, (2) assumptions about potential limiting factors, (3) explicit relationships between wildfowl abundance and habitat characteristics, (4) numeric foraging habitat goals, and (5) criteria for evaluating success. The population goal of the Joint Venture for the Mississippi Alluvial Valley (MA V) is to enable 4.3 million ducks to, survive winter and join continental breeding populations in spring. Currently, available data suggest that foraging habitat is the primary factor limiting duck populations in the MA II. To establish a goal for foraging habitat, we assumed the length of the wintering period is 110 days and calculated that a population of 4.3 million breeding ducks (plus 15% to account for winter mortality) would need 546 million duck-days of food in the preceding winter. Then, we used estimates of daily energy requirements, food densities, and food energy values to calculate the carrying capacity or number of duck-days of food available in the three primary foraging habitats in the MAV (flooded croplands, forested wetlands, and moist-soil wetlands). Thus, availability of foraging habitat can be used as a criterion for evaluating success of the Joint Venture if accurate inventories of foraging habitat can be conducted. Development of an explicit biological framework for the Joint Venture enabled wildfowl managers and researchers to establish specific objectives for management of foraging habitat and identify priority problems requiring further study.

Behavioral Effects of an Enhanced Enrichment Program for Group-Housed Sooty Mangabeys (Cercocebus atys)

PubMed Central

Crast, Jessica; Bloomsmith, Mollie A; Jonesteller, Trina J

2016-01-01

Evaluating the behavioral effects of enrichment on animals housed in biomedical facilities is necessary to effectively support their care and wellbeing. We tested the cumulative effects of an enhanced enrichment program on sooty mangabey behavior: locomotion, feeding and foraging, manipulating items in the enclosure, social affiliation, aggression, and abnormal behavior. The enhanced enrichment program included the addition of a substrate (timothy hay), widely distributing small pieces of produce and a forage mixture in the hay, adding structures and perching, and increasing the variety of food items, foraging devices, and other manipulable items. We tested 10 groups living in runs (n = 54) by using an ABA experimental design (phase A, standard enrichment; phase B, enhanced enrichment) and Wilcoxon signed-rank tests to compare behavior across phases. During phase B, subjects significantly increased feeding, foraging, and manipulation of items, and they decreased self-grooming, social affiliation, and aggression. Combined enrichment use increased from approximately 10% to 21% of the mangabeys’ time. Enhanced enrichment did not affect locomotion or abnormal behavior. The increases in feeding, foraging, and manipulation during enhanced enrichment were driven primarily by the subjects’ preference for foraging in the hay: it was the most effective component of the program in promoting feeding and foraging behavior, which comprises the majority of wild sooty mangabeys’ daily activity. Developing an effective, species-appropriate, and comprehensive enrichment program is essential to successfully promote the health and wellbeing of captive NHP. PMID:27931313

Behavioral Effects of an Enhanced Enrichment Program for Group-Housed Sooty Mangabeys (Cercocebus atys).

PubMed

Crast, Jessica; Bloomsmith, Mollie A; Jonesteller, Trina J

2016-11-01

Evaluating the behavioral effects of enrichment on animals housed in biomedical facilities is necessary to effectively support their care and wellbeing. We tested the cumulative effects of an enhanced enrichment program on sooty mangabey behavior: locomotion, feeding and foraging, manipulating items in the enclosure, social affiliation, aggression, and abnormal behavior. The enhanced enrichment program included the addition of a substrate (timothy hay), widely distributing small pieces of produce and a forage mixture in the hay, adding structures and perching, and increasing the variety of food items, foraging devices, and other manipulable items. We tested 10 groups living in runs (n = 54) by using an ABA experimental design (phase A, standard enrichment; phase B, enhanced enrichment) and Wilcoxon signed-rank tests to compare behavior across phases. During phase B, subjects significantly increased feeding, foraging, and manipulation of items, and they decreased self-grooming, social affiliation, and aggression. Combined enrichment use increased from approximately 10% to 21% of the mangabeys' time. Enhanced enrichment did not affect locomotion or abnormal behavior. The increases in feeding, foraging, and manipulation during enhanced enrichment were driven primarily by the subjects' preference for foraging in the hay: it was the most effective component of the program in promoting feeding and foraging behavior, which comprises the majority of wild sooty mangabeys' daily activity. Developing an effective, species-appropriate, and comprehensive enrichment program is essential to successfully promote the health and wellbeing of captive NHP.

Conservation seeding and diverse seed species performance

USDA-ARS?s Scientific Manuscript database

The rehabilitation of degraded big sagebrush (Artemisia spp.) communities infested with cheatgrass (Bromus tectorum) and other competitive weeds is a daunting task facing resource managers and land owners. In an effort to improve wildlife and livestock forage on degraded rangelands, the USDA-ARS-Gr...

Supplementing a ruminally undegradable protein supplement to maintain essential amino acid supply to the small intestine when forage intake is restricted in beef cattle.

PubMed

Scholljegerdes, E J; Weston, T R; Ludden, P A; Hess, B W

2005-09-01

Twelve Angus crossbred cattle (eight heifers and four steers; average initial BW = 594 +/- 44.4 kg) fitted with ruminal and duodenal cannulas and fed restricted amounts of forage plus a ruminally undegradable protein (RUP) supplement were used in a triplicated 4 x 4 Latin square design experiment to determine intestinal supply of essential AA. Cattle were fed four different levels of chopped (2.54 cm) bromegrass hay (11.4% CP, 57% NDF; OM basis): 30, 55, 80, or 105% of the forage intake required for maintenance. Cattle fed below maintenance were given specified quantities of a RUP supplement (6.8% porcine blood meal, 24.5% hydrolyzed feather meal, and 68.7% menhaden fish meal; DM basis) designed to provide duodenal essential AA flow equal to that of cattle fed forage at 105% of maintenance. Experimental periods lasted 21 d (17 d of adaptation and 4 d of sampling). Total OM intake and duodenal OM flow increased linearly (P < 0.001) as cattle consumed more forage; however, OM truly digested in the rumen (% of intake) did not change (P = 0.43) as intake increased. True ruminal N degradation (% of intake) tended (P = 0.07) to increase linearly, and true ruminal N degradation (g/d) decreased quadratically (P = 0.02) as intake increased from 30 to 105%. Duodenal N flow was equal (P = 0.33) across intake levels, even though microbial N flow increased linearly (P < 0.001) as forage OM intake increased. Total and individual essential AA intake decreased (cubic; P < 0.001) as forage intake increased because the supply of nonammonia, nonmicrobial N flow from RUP was decreased (linear; P < 0.001) by design. Total duodenal flow of essential AA did not differ (P = 0.39) across these levels of forage intake. Although the profile of essential AA reaching the duodenum differed (P < or = 0.02) for all 10 essential AA, the range of each essential AA as a proportion of total essential AA was low (11.1 to 11.2% of total essential AA for phenylalanine to 12.3 to 14.3% of total essential AA for lysine). Duodenal essential AA flow did not differ (P = 0.10 to 0.65) with forage intake level for eight of the 10 essential AA. Duodenal flow of arginine decreased linearly (P = 0.01), whereas duodenal flow of tryptophan increased linearly (P = 0.002) as forage intake increased from 30 to 105% of maintenance. Balancing intestinal essential AA supply in beef cattle can be accomplished by varying intake of a RUP supplement.

Multiple-stage decisions in a marine central-place forager

PubMed Central

Friedlaender, Ari S.; Johnston, David W.; Tyson, Reny B.; Kaltenberg, Amanda; Goldbogen, Jeremy A.; Stimpert, Alison K.; Curtice, Corrie; Hazen, Elliott L.; Halpin, Patrick N.; Read, Andrew J.; Nowacek, Douglas P.

2016-01-01

Air-breathing marine animals face a complex set of physical challenges associated with diving that affect the decisions of how to optimize feeding. Baleen whales (Mysticeti) have evolved bulk-filter feeding mechanisms to efficiently feed on dense prey patches. Baleen whales are central place foragers where oxygen at the surface represents the central place and depth acts as the distance to prey. Although hypothesized that baleen whales will target the densest prey patches anywhere in the water column, how depth and density interact to influence foraging behaviour is poorly understood. We used multi-sensor archival tags and active acoustics to quantify Antarctic humpback whale foraging behaviour relative to prey. Our analyses reveal multi-stage foraging decisions driven by both krill depth and density. During daylight hours when whales did not feed, krill were found in deep high-density patches. As krill migrated vertically into larger and less dense patches near the surface, whales began to forage. During foraging bouts, we found that feeding rates (number of feeding lunges per hour) were greatest when prey was shallowest, and feeding rates decreased with increasing dive depth. This strategy is consistent with previous models of how air-breathing diving animals optimize foraging efficiency. Thus, humpback whales forage mainly when prey is more broadly distributed and shallower, presumably to minimize diving and searching costs and to increase feeding rates overall and thus foraging efficiency. Using direct measurements of feeding behaviour from animal-borne tags and prey availability from echosounders, our study demonstrates a multi-stage foraging process in a central place forager that we suggest acts to optimize overall efficiency by maximizing net energy gain over time. These data reveal a previously unrecognized level of complexity in predator–prey interactions and underscores the need to simultaneously measure prey distribution in marine central place forager studies. PMID:27293784

The tremble dance of honey bees can be caused by hive-external foraging experience.

PubMed

Thom, Corinna

2003-07-01

The tremble dance of honey bee nectar foragers is part of the communication system that regulates a colony's foraging efficiency. A forager that returns to the hive with nectar, but then experiences a long unloading delay because she has difficulty finding a nectar receiver bee, will perform a tremble dance to recruit additional nectar receiver bees. A forager that experiences a short unloading delay will perform a waggle dance to recruit more nectar foragers. A long unloading delay was until now the only known cause of tremble dancing. However, several studies suggested that factors at the food source may also cause tremble dancing. Here I test whether one of these factors, crowding of nectar foragers at the food source, stimulates tremble dancing because it causes long unloading delays. To do so, I increased the density of nectar foragers at a food source by suddenly reducing the size of an artificial feeder, and recorded the unloading delay experienced by each forager, as well as the dance she performed, if any. A forager's unloading delay was measured as the time interval between entering the hive and either (1) the first unloading contact with a nectar receiver bee, or (2) the start of the first dance, if dancing began before the first unloading contact. I also recorded the unloading delays and dances of nectar foragers that returned from natural food sources. The results show that crowding of nectar foragers at the food source increases the probability of tremble dancing, but does not cause long unloading delays, and that tremble dancers that foraged at natural food sources also often have short unloading delays. When the cause of the tremble dance is not a low supply of nectar receiver bees, the tremble dance may have a function in addition to the recruitment of nectar receiver bees.

Nectar loads as fuel for collecting nectar and pollen in honeybees: adjustment by sugar concentration.

PubMed

Harano, Ken-Ichi; Nakamura, Jun

2016-06-01

When honeybee foragers leave the nest, they receive nectar from nest mates for use as fuel for flight or as binding material to build pollen loads. We examined whether the concentration of nectar carried from the nest changes with the need for sugar. We found that pollen foragers had more-concentrated nectar (61.8 %) than nectar foragers (43.8 %). Further analysis revealed that the sugar concentration of the crop load increased significantly with waggle duration, an indicator of food-source distance, in both groups of foragers. Crop volume also increased with waggle duration. The results support our argument that foragers use concentrated nectar when the need for sugar is high and suggest that they precisely adjust the amount of sugar in the crop by altering both volume and nectar concentrations. We also investigated the impact of the area where foragers receive nectar on the crop load concentration at departure. Although nectar and pollen foragers tend to load nectar at different areas in the nest, area did not have a significant effect on crop load concentration. Departing foragers showed an average of 2.2 momentary (<1 s) begging trophallactic contacts before leaving the nest. They might be rejecting nectar with inappropriate concentrations during these contacts.

Age variation in the body coloration of the orb-weaver spider Alpaida tuonabo and its implications on foraging.

PubMed

Gálvez, Dumas; Añino, Yostin; De la O, Jorge M

2018-02-26

Spiders show a repertoire of strategies to increase their foraging success. In particular, some orb-weaver spiders use attractive body colorations to lure prey. Interestingly, coloration varies with age in many species, which may result in ontogenetic variation of foraging success. By using field observations, laboratory experiments and spectrophotometric analysis, we investigated whether pale juveniles and bright adults of the orb-weaver Alpaida tuonabo use different foraging strategies due to ontogenetic variation in coloration. Field observations revealed that foraging success of juveniles and adults was influenced by web properties. However, foraging success increased with body size only in adults, supporting the idea that larger individuals produce a stronger visual signal for prey. The attractiveness of the adult coloration for prey was confirmed in the laboratory with frame-web-choice experiments, in which webs bearing a spider intercepted more bees than empty webs. Our spectrophotometric analysis suggests that the yellow coloration may produce the deceiving signal for prey. Moreover, we identified potential alternative foraging strategies: cryptic juveniles at higher heights and 'attractive' adults at lower heights. This study reveals how ontogenetic colour variation may favour the use of alternative foraging strategies in orb-weaver spiders and reduces intraspecific competition.

Windscapes shape seabird instantaneous energy costs but adult behavior buffers impact on offspring.

PubMed

Elliott, Kyle Hamish; Chivers, Lorraine S; Bessey, Lauren; Gaston, Anthony J; Hatch, Scott A; Kato, Akiko; Osborne, Orla; Ropert-Coudert, Yan; Speakman, John R; Hare, James F

2014-01-01

Windscapes affect energy costs for flying animals, but animals can adjust their behavior to accommodate wind-induced energy costs. Theory predicts that flying animals should decrease air speed to compensate for increased tailwind speed and increase air speed to compensate for increased crosswind speed. In addition, animals are expected to vary their foraging effort in time and space to maximize energy efficiency across variable windscapes. We examined the influence of wind on seabird (thick-billed murre Uria lomvia and black-legged kittiwake Rissa tridactyla) foraging behavior. Airspeed and mechanical flight costs (dynamic body acceleration and wing beat frequency) increased with headwind speed during commuting flights. As predicted, birds adjusted their airspeed to compensate for crosswinds and to reduce the effect of a headwind, but they could not completely compensate for the latter. As we were able to account for the effect of sampling frequency and wind speed, we accurately estimated commuting flight speed with no wind as 16.6 ms(?1) (murres) and 10.6 ms(?1) (kittiwakes). High winds decreased delivery rates of schooling fish (murres), energy (murres) and food (kittiwakes) but did not impact daily energy expenditure or chick growth rates. During high winds, murres switched from feeding their offspring with schooling fish, which required substantial above-water searching, to amphipods, which required less above-water searching. Adults buffered the adverse effect of high winds on chick growth rates by switching to other food sources during windy days or increasing food delivery rates when weather improved.

Vigilance and feeding behaviour in large feeding flocks of laughing gulls, Larus atricilla, on Delaware Bay

NASA Astrophysics Data System (ADS)

Burger, Joanna; Gochfeld, Michael

1991-02-01

Laughing gulls ( Larus atricilla) forage on horseshoe crab ( Limulus polyphemus) eggs during May in Delaware Bay each year. They feed in dense flocks, and foraging rates vary with vigilance, bird density, number of steps and location in the flock, whereas time devoted to vigilance is explained by number of steps, density, location and feeding rates. The time devoted to vigilance decreases with increasing density, increasing foraging rates and decreasing aggression. Birds foraging on the edge of flocks take fewer pecks and more steps, and devote more time to vigilance than those in the intermediate or central parts of a flock.

Relating ranging ecology, limb length, and locomotor economy in terrestrial animals.

PubMed

Pontzer, Herman

2012-03-07

Ecomorphological analyses have identified a number of important evolutionary trends in vertebrate limb design, but the relationships between daily travel distance, locomotor ecology, and limb length in terrestrial animals remain poorly understood. In this paper I model the net rate of energy intake as a function of foraging efficiency, and thus of locomotor economy; improved economy leads to greater net energy intake. However, the relationship between locomotor economy and net intake is highly dependent on foraging efficiency; only species with low foraging efficiencies experience strong selection pressure for improved locomotor economy and increased limb length. Examining 237 terrestrial species, I find that nearly all taxa obtain sufficiently high foraging efficiencies that selection for further increases in economy is weak. Thus selection pressures for increased economy and limb length among living terrestrial animals may be relatively weak and similar in magnitude across ecologically diverse species. The Economy Selection Pressure model for locomotor economy may be useful in investigating the evolution of limb design in early terrestrial taxa and the coevolution of foraging ecology and locomotor anatomy in lineages with low foraging efficiencies. Copyright © 2011 Elsevier Ltd. All rights reserved.

Skills, division of labour and economies of scale among Amazonian hunters and South Indian honey collectors.

PubMed

Hooper, Paul L; Demps, Kathryn; Gurven, Michael; Gerkey, Drew; Kaplan, Hillard S

2015-12-05

In foraging and other productive activities, individuals make choices regarding whether and with whom to cooperate, and in what capacities. The size and composition of cooperative groups can be understood as a self-organized outcome of these choices, which are made under local ecological and social constraints. This article describes a theoretical framework for explaining the size and composition of foraging groups based on three principles: (i) the sexual division of labour; (ii) the intergenerational division of labour; and (iii) economies of scale in production. We test predictions from the theory with data from two field contexts: Tsimane' game hunters of lowland Bolivia, and Jenu Kuruba honey collectors of South India. In each case, we estimate the impacts of group size and individual group members' effort on group success. We characterize differences in the skill requirements of different foraging activities and show that individuals participate more frequently in activities in which they are more efficient. We evaluate returns to scale across different resource types and observe higher returns at larger group sizes in foraging activities (such as hunting large game) that benefit from coordinated and complementary roles. These results inform us that the foraging group size and composition are guided by the motivated choice of individuals on the basis of relative efficiency, benefits of cooperation, opportunity costs and other social considerations. © 2015 The Author(s).

DNA barcoding reveals seasonal shifts in diet and consumption of deep-sea fishes in wedge-tailed shearwaters

PubMed Central

Ando, Haruko; Horikoshi, Kazuo; Suzuki, Hajime; Isagi, Yuji

2018-01-01

The foraging ecology of pelagic seabirds is difficult to characterize because of their large foraging areas. In the face of this difficulty, DNA metabarcoding may be a useful approach to analyze diet compositions and foraging behaviors. Using this approach, we investigated the diet composition and its seasonal variation of a common seabird species on the Ogasawara Islands, Japan: the wedge-tailed shearwater Ardenna pacifica. We collected fecal samples during the prebreeding (N = 73) and rearing (N = 96) periods. The diet composition of wedge-tailed shearwater was analyzed by Ion Torrent sequencing using two universal polymerase chain reaction primers for the 12S and 16S mitochondrial DNA regions that targeted vertebrates and mollusks, respectively. The results of a BLAST search of obtained sequences detected 31 and 1 vertebrate and mollusk taxa, respectively. The results of the diet composition analysis showed that wedge-tailed shearwaters frequently consumed deep-sea fishes throughout the sampling season, indicating the importance of these fishes as a stable food resource. However, there was a marked seasonal shift in diet, which may reflect seasonal changes in food resource availability and wedge-tailed shearwater foraging behavior. The collected data regarding the shearwater diet may be useful for in situ conservation efforts. Future research that combines DNA metabarcoding with other tools, such as data logging, may provide further insight into the foraging ecology of pelagic seabirds. PMID:29630670

Comparison of alternative beef production systems based on forage finishing or grain-forage diets with or without growth promotants: 2. Meat quality, fatty acid composition, and overall palatability.

PubMed

Faucitano, L; Chouinard, P Y; Fortin, J; Mandell, I B; Lafrenière, C; Girard, C L; Berthiaume, R

2008-07-01

Five beef cattle management regimens were evaluated for their effect on meat quality, fatty acid composition, and overall palatability of the longis-simus dorsi (LD) muscle in Angus cross steers. A 98-d growing phase was conducted using grass silage with or without supplementation of growth promotants (Revalor G and Rumensin) or soybean meal. Dietary treatments in the finishing phase were developed with or without supplementation of growth promotants based on exclusive feeding of forages with no grain supplementation, or the feeding of grain:forage (70:30) diets. Growth promotants increased (P < 0.01) shear force and tended (P = 0.06) to increase toughness of the LD muscle due to limited postmortem proteolytic activity (lower myofibrillar fragmentation index value; P = 0.02). Grain feeding increased DM and intramuscular fat content (P = 0.03 and P = 0.05, respectively) in the LD but decreased the sensory panel tenderness score (P = 0.01). Growth promotants increased (P

Effects of feeding salt-tolerant forage cultivated in saline-alkaline land on rumen fermentation, feed digestibility and nitrogen balance in lamb.

PubMed

Wang, Cong; Dong, Kuan Hu; Liu, Qiang; Yang, Wen Zhu; Zhao, Xiang; Liu, Sheng Qiang; He, Ting Ting; Liu, Zhuang Yu

2011-05-01

Mixing salt-tolerant plants with other plants may affect rumen fermentation, which could result in an increase of feed conversion rate. The objective of this study was to evaluate the effects of partially or entirely replacing the corn stover with a mixture of salt-tolerant forage (Dahurian wildrye grass, weeping alkaligrass and erect milkvetch) in the diet of lambs on ruminal fermentation, feed digestibility and nitrogen (N) balance. Ratios of corn stover to the mixture of salt-tolerant forages in the four experimental diets were 100:0, 67:33, 33:67 and 0:100, respectively, for control, low (LF), medium (MF) and high (HF). Ruminal pH was lower (P = 0.048) with LF and MF than with control and HF diets. Total VFA concentration was consistently higher (P = 0.039) for LF and MF than for control and HF with increasing amount of salt-tolerant forage. Ratio of acetate to propionate was linearly (P = 0.019) decreased due to the decrease in acetate production. Digestibilities of OM, NDF and CP in the whole tract linearly (P < 0.002) decreased with increasing amount of salt-tolerant forage. Similarly, retained N and ratio of retained N to digestible N also linearly (P < 0.005) decreased. Feeding salt-tolerant forage cultivated in saline-alkaline land improved rumen fermentation with increased total VFA production, and changed the rumen fermentation pattern to increased butyrate production. However, the decreased feed digestibility in the whole digestive tract of lamb may reduce nutrient availability to animals and thus adversely affect animal productivity. Additionally, feeding salt-tolerant forages may require more protein supplement to meet animal requirements, because of the low protein content and low protein digestibility of the salt-tolerant forages. Copyright © 2011 Society of Chemical Industry.

Assessing the Effects of Grassland Management on Forage Production and Environmental Quality to Identify Paths to Ecological Intensification in Mountain Grasslands.

PubMed

Loucougaray, Grégory; Dobremez, Laurent; Gos, Pierre; Pauthenet, Yves; Nettier, Baptiste; Lavorel, Sandra

2015-11-01

Ecological intensification in grasslands can be regarded as a process for increasing forage production while maintaining high levels of ecosystem functions and biodiversity. In the mountain Vercors massif, where dairy cattle farming is the main component of agriculture, how to achieve forage autonomy at farm level while sustaining environmental quality for tourism and local dairy products has recently stimulated local debate. As specific management is one of the main drivers of ecosystem functioning, we assessed the response of forage production and environmental quality at grassland scale across a wide range of management practices. We aimed to determine which components of management can be harnessed to better match forage production and environmental quality. We sampled the vegetation of 51 grasslands stratified across 13 grassland types. We assessed each grassland for agronomic and environmental properties, measuring forage production, forage quality, and indices based on the abundance of particular plant species such as timing flexibility, apiarian potential, and aromatic plants. Our results revealed an expected trade-off between forage production and environmental quality, notably by stressing the contrasts between sown and permanent grasslands. However, strong within-type variability in both production and environmental quality as well as in flexibility of timing of use suggests possible ways to improve this trade-off at grassland and farm scales. As achieving forage autonomy relies on increasing both forage production and grassland resilience, our results highlight the critical role of the ratio between sown and permanent grasslands as a major path for ecological intensification in mountain grasslands.

Experience-dependent plasticity in the mushroom bodies of the solitary bee Osmia lignaria (Megachilidae).

PubMed

Withers, Ginger S; Day, Nancy F; Talbot, Emily F; Dobson, Heidi E M; Wallace, Christopher S

2008-01-01

All members of the solitary bee species Osmia lignaria (the orchard bee) forage upon emergence from their natal nest cell. Conversely, in the honey bee, days-to-weeks of socially regulated behavioral development precede the onset of foraging. The social honey bee's behavioral transition to foraging is accompanied by neuroanatomical changes in the mushroom bodies, a region of the insect brain implicated in learning. If these changes were general adaptations to foraging, they should also occur in the solitary orchard bee. Using unbiased stereological methods, we estimated the volume of the major compartments of the mushroom bodies, the neuropil and Kenyon cell body region, in adult orchard bees. We compared the mushroom bodies of recently emerged bees with mature bees that had extensive foraging experience. To separate effects of general maturation from field foraging, some orchard bees were confined to a cage indoors. The mushroom body neuropil of experienced field foragers was significantly greater than that of both recently emerged and mature caged orchard bees, suggesting that, like the honey bee, this increase is driven by outdoor foraging experience. Unlike the honey bee, where increases in the ratio of neuropil to Kenyon cell region occur in the worker after emerging from the hive cell, the orchard bee emerged from the natal nest cell with a ratio that did not change with maturation and was comparable to honey-bee foragers. These results suggest that a common developmental endpoint may be reached via different development paths in social and solitary species of foraging bees.

Boldness predicts an individual's position along an exploration-exploitation foraging trade-off.

PubMed

Patrick, Samantha C; Pinaud, David; Weimerskirch, Henri

2017-09-01

Individuals do not have complete information about the environment and therefore they face a trade-off between gathering information (exploration) and gathering resources (exploitation). Studies have shown individual differences in components of this trade-off but how stable these strategies are in a population and the intrinsic drivers of these differences is not well understood. Top marine predators are expected to experience a particularly strong trade-off as many species have large foraging ranges and their prey often have a patchy distribution. This environment leads these species to exhibit pronounced exploration and exploitation phases but differences between individuals are poorly resolved. Personality differences are known to be important in foraging behaviour but also in the trade-off between exploration and exploitation. Here we test whether personality predicts an individual exploration-exploitation strategy using wide ranging wandering albatrosses (Diomedea exulans) as a model system. Using GPS tracking data from 276 wandering albatrosses, we extract foraging parameters indicative of exploration (searching) and exploitation (foraging) and show that foraging effort, time in patch and size of patch are strongly correlated, demonstrating these are indicative of an exploration-exploitation (EE) strategy. Furthermore, we show these are consistent within individuals and appear stable in the population, with no reproductive advantage. The searching and foraging behaviour of bolder birds placed them towards the exploration end of the trade-off, whereas shy birds showed greater exploitation. This result provides a mechanism through which individual foraging strategies may emerge. Age and sex affected components of the trade-off, but not the trade-off itself, suggesting these factors may drive behavioural compensation to maintain resource acquisition and this was supported by the evidence that there were no fitness consequence of any EE trait nor the trade-off itself. These results demonstrate a clear trade-off between information gathering and exploitation of prey patches, and reveals for the first time that boldness may drive these differences. This provides a mechanism through which widely reported links between personality and foraging may emerge. © 2017 The Authors. Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.

Foraging areas, offshore habitat use, and colony overlap by incubating Leach’s storm-petrels Oceanodroma leucorhoa in the Northwest Atlantic

PubMed Central

Hedd, April; Pollet, Ingrid L.; Mauck, Robert A.; Burke, Chantelle M.; Mallory, Mark L.; McFarlane Tranquilla, Laura A.; Montevecchi, William A.; Robertson, Gregory J.; Ronconi, Robert A.; Shutler, Dave; Wilhelm, Sabina I.; Burgess, Neil M.

2018-01-01

Despite their importance in marine food webs, much has yet to be learned about the spatial ecology of small seabirds. This includes the Leach’s storm-petrel Oceanodroma leucorhoa, a species that is declining throughout its Northwest Atlantic breeding range. In 2013 and 2014, we used global location sensors to track foraging movements of incubating storm-petrels from 7 eastern Canadian breeding colonies. We determined and compared the foraging trip and at-sea habitat characteristics, analysed spatial overlap among colonies, and determined whether colony foraging ranges intersected with offshore oil and gas operations. Individuals tracked during the incubation period made 4.0 ± 1.4 day foraging trips, travelling to highly pelagic waters over and beyond continental slopes which ranged, on average, 400 to 830 km from colonies. Cumulative travel distances ranged from ~900 to 2,100 km among colonies. While colony size did not influence foraging trip characteristics or the size of areas used at sea, foraging distances tended to be shorter for individuals breeding at the southern end of the range. Core areas did not overlap considerably among colonies, and individuals from all sites except Kent Island in the Bay of Fundy foraged over waters with median depths > 1,950 m and average chlorophyll a concentrations ≤ 0.6 mg/m3. Sea surface temperatures within colony core areas varied considerably (11–23°C), coincident with the birds’ use of cold waters of the Labrador Current or warmer waters of the Gulf Stream Current. Offshore oil and gas operations intersected with the foraging ranges of 5 of 7 colonies. Three of these, including Baccalieu Island, Newfoundland, which supports the species’ largest population, have experienced substantial declines in the last few decades. Future work should prioritize modelling efforts to incorporate information on relative predation risk at colonies, spatially explicit risks at-sea on the breeding and wintering grounds, effects of climate and marine ecosystem change, as well as lethal and sub-lethal effects of environmental contaminants, to better understand drivers of Leach’s storm-petrel populations trends in Atlantic Canada. PMID:29742124

Seed storage effects on germination for two forage kochia cultivars

USDA-ARS?s Scientific Manuscript database

The cultivar ‘Snowstorm’ forage kochia was released by the USDA-ARS in 2012. It is a synthetic cultivar selected for stature, forage production, and adaptation to semiarid environments. Similar to the earlier released (1984) ‘Immigrant’ cultivar it can increase rangeland productivity magnitudes when...

Prescribed fire effects on resource selection by cattle in mesic sagebrush steppe. Part 2: Mid-summer grazing

USDA-ARS?s Scientific Manuscript database

Prescribed fire can release herbaceous forages from woody plant competition thus promoting increased forage plant production, vigor, and accessibility. Prescribe fire also consumes standing litter thereby improving forage quality and palatability. Consequently, prescribed fire is commonly consider...

Transgenic Alfalfa Plants Expressing the Sweetpotato Orange Gene Exhibit Enhanced Abiotic Stress Tolerance

PubMed Central

Wang, Zhi; Ke, Qingbo; Kim, Myoung Duck; Kim, Sun Ha; Ji, Chang Yoon; Jeong, Jae Cheol; Lee, Haeng-Soon; Park, Woo Sung; Ahn, Mi-Jeong; Li, Hongbing; Xu, Bingcheng; Deng, Xiping; Lee, Sang-Hoon; Lim, Yong Pyo; Kwak, Sang-Soo

2015-01-01

Alfalfa (Medicago sativa L.), a perennial forage crop with high nutritional content, is widely distributed in various environments worldwide. We recently demonstrated that the sweetpotato Orange gene (IbOr) is involved in increasing carotenoid accumulation and enhancing resistance to multiple abiotic stresses. In this study, in an effort to improve the nutritional quality and environmental stress tolerance of alfalfa, we transferred the IbOr gene into alfalfa (cv. Xinjiang Daye) under the control of an oxidative stress-inducible peroxidase (SWPA2) promoter through Agrobacterium tumefaciens-mediated transformation. Among the 11 transgenic alfalfa lines (referred to as SOR plants), three lines (SOR2, SOR3, and SOR8) selected based on their IbOr transcript levels were examined for their tolerance to methyl viologen (MV)-induced oxidative stress in a leaf disc assay. The SOR plants exhibited less damage in response to MV-mediated oxidative stress and salt stress than non-transgenic plants. The SOR plants also exhibited enhanced tolerance to drought stress, along with higher total carotenoid levels. The results suggest that SOR alfalfa plants would be useful as forage crops with improved nutritional value and increased tolerance to multiple abiotic stresses, which would enhance the development of sustainable agriculture on marginal lands. PMID:25946429

Transgenic alfalfa plants expressing the sweetpotato Orange gene exhibit enhanced abiotic stress tolerance.

PubMed

Wang, Zhi; Ke, Qingbo; Kim, Myoung Duck; Kim, Sun Ha; Ji, Chang Yoon; Jeong, Jae Cheol; Lee, Haeng-Soon; Park, Woo Sung; Ahn, Mi-Jeong; Li, Hongbing; Xu, Bingcheng; Deng, Xiping; Lee, Sang-Hoon; Lim, Yong Pyo; Kwak, Sang-Soo

2015-01-01

Alfalfa (Medicago sativa L.), a perennial forage crop with high nutritional content, is widely distributed in various environments worldwide. We recently demonstrated that the sweetpotato Orange gene (IbOr) is involved in increasing carotenoid accumulation and enhancing resistance to multiple abiotic stresses. In this study, in an effort to improve the nutritional quality and environmental stress tolerance of alfalfa, we transferred the IbOr gene into alfalfa (cv. Xinjiang Daye) under the control of an oxidative stress-inducible peroxidase (SWPA2) promoter through Agrobacterium tumefaciens-mediated transformation. Among the 11 transgenic alfalfa lines (referred to as SOR plants), three lines (SOR2, SOR3, and SOR8) selected based on their IbOr transcript levels were examined for their tolerance to methyl viologen (MV)-induced oxidative stress in a leaf disc assay. The SOR plants exhibited less damage in response to MV-mediated oxidative stress and salt stress than non-transgenic plants. The SOR plants also exhibited enhanced tolerance to drought stress, along with higher total carotenoid levels. The results suggest that SOR alfalfa plants would be useful as forage crops with improved nutritional value and increased tolerance to multiple abiotic stresses, which would enhance the development of sustainable agriculture on marginal lands.

Quasi-planktonic behavior of foraging top marine predators

PubMed Central

Della Penna, Alice; De Monte, Silvia; Kestenare, Elodie; Guinet, Christophe; d’Ovidio, Francesco

2015-01-01

Monitoring marine top predators is fundamental for assessing the health and functioning of open ocean ecosystems. Although recently tracking observations have substantially increased, factors determining the horizontal exploration of the ocean by marine predators are still largely unknown, especially at the scale of behavioral switches (1–100 km, days-weeks). It is commonly assumed that the influence of water movement can be neglected for animals capable of swimming faster than the current. Here, we challenge this assumption by combining the use of biologging (GPS and accelerometry), satellite altimetry and in-situ oceanographic data (ADCP and drifting buoys) to investigate the effect of the mesoscale ocean dynamics on a marine predator, the southern elephant seal. A Lagrangian approach reveals that trajectories of elephant seals are characterized by quasi-planktonic bouts where the animals are horizontally drifting. These bouts correspond to periods of increased foraging effort, indicating that in the quasi-planktonic conditions energy is allocated to diving and chasing, rather than in horizontal search of favourable grounds. These results suggest that mesoscale features like eddies and fronts may act as a focal points for trophic interactions not only by bottom-up modulation of nutrient injection, but also by directly entraining horizontal displacements of the upper trophic levels. PMID:26666350

Infectious disease, behavioural flexibility and the evolution of culture in primates.

PubMed

McCabe, Collin M; Reader, Simon M; Nunn, Charles L

2015-01-22

Culturally transmitted traits are observed in a wide array of animal species, yet we understand little about the costs of the behavioural patterns that underlie culture, such as innovation and social learning. We propose that infectious diseases are a significant cost associated with cultural transmission. We investigated two hypotheses that may explain such a connection: that social learning and exploratory behaviours (specifically, innovation and extractive foraging) either compensate for existing infection or increase exposure to infectious agents. We used Bayesian comparative methods, controlling for sampling effort, body mass, group size, geographical range size, terrestriality, latitude and phylogenetic uncertainty. Across 127 primate species, we found a positive association between pathogen richness and rates of innovation, extractive foraging and social learning. This relationship was driven by two independent phenomena: socially contagious diseases were positively associated with rates of social learning, and environmentally transmitted diseases were positively associated with rates of exploration. Because higher pathogen burdens can contribute to morbidity and mortality, we propose that parasitism is a significant cost associated with the behavioural patterns that underpin culture, and that increased pathogen exposure is likely to have played an important role in the evolution of culture in both non-human primates and humans. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Wetland use and feeding by lesser scaup during spring migration across the upper Midwest, USA

USGS Publications Warehouse

Anteau, M.J.; Afton, A.D.

2009-01-01

Low food availability and forage quality and concomitant decreased lipid reserves of lesser scaup (Aythya affinis; hereafter scaup) during spring migration in the upper Midwest may partially explain reductions in the continental population of scaup. In springs 20042005, we examined wetland use and feeding activity of scaup on 356 randomly-selected wetlands within 6 regions in Iowa, Minnesota, and North Dakota. We examined wetland characteristics that favor high scaup use in 286 of these wetlands. We found that probabilities of wetland use and feeding by scaup increased with turbidity up to 45 and 30 NTU, respectively, but then declined at higher turbidity levels. Wetland use was positively correlated with size of open-water zone and amphipod densities, but was not correlated with chironomid densities. Feeding increased with amphipod density up to 26 m-3 and then declined at higher amphipod densities; scaup seemingly forage most efficiently at amphipod densities above 26 m -3. Wetland use was higher in North Dakota than in southern Minnesota and Iowa. Our results indicate that effective wetland restoration efforts to benefit scaup require maintaining abundant populations of amphipods (generally near 26 m-3 landscape geometric mean) in wetlands with large (> 500 m diameter) open-water zones throughout the upper Midwest, but especially within Iowa and southern Minnesota.

Systems assessment of water savings impact of controlled environment agriculture (CEA) utilizing wirelessly networked Sense•Decide•Act•Communicate (SDAC) systems.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campbell, Jonathan T.; Baynes, Edward E., Jr.; Aguirre,Carlos

Reducing agricultural water use in arid regions while maintaining or improving economic productivity of the agriculture sector is a major challenge. Controlled environment agriculture (CEA, or, greenhouse agriculture) affords advantages in direct resource use (less land and water required) and productivity (i.e., much higher product yield and quality per unit of resources used) relative to conventional open-field practices. These advantages come at the price of higher operating complexity and costs per acre. The challenge is to implement and apply CEA such that the productivity and resource use advantages will sufficiently outweigh the higher operating costs to provide for overall benefitmore » and viability. This project undertook an investigation of CEA for livestock forage production as a water-saving alternative to open-field forage production in arid regions. Forage production is a large consumer of fresh water in many arid regions of the world, including the southwestern U.S. and northern Mexico. With increasing competition among uses (agriculture, municipalities, industry, recreation, ecosystems, etc.) for limited fresh water supplies, agricultural practice alternatives that can potentially maintain or enhance productivity while reducing water use warrant consideration. The project established a pilot forage production greenhouse facility in southern New Mexico based on a relatively modest and passive (no active heating or cooling) system design pioneered in Chihuahua, Mexico. Experimental operations were initiated in August 2004 and carried over into early-FY05 to collect data and make initial assessments of operational and technical system performance, assess forage nutrition content and suitability for livestock, identify areas needing improvement, and make initial assessment of overall feasibility. The effort was supported through the joint leveraging of late-start FY04 LDRD funds and bundled CY2004 project funding from the New Mexico Small Business Technical Assistance program at Sandia. Despite lack of optimization with the project system, initial results show the dramatic water savings potential of hydroponic forage production compared with traditional irrigated open field practice. This project produced forage using only about 4.5% of the water required for equivalent open field production. Improved operation could bring water use to 2% or less. The hydroponic forage production system and process used in this project are labor intensive and not optimized for minimum water usage. Freshly harvested hydroponic forage has high moisture content that dilutes its nutritional value by requiring that livestock consume more of it to get the same nutritional content as conventional forage. In most other aspects the nutritional content compares well on a dry weight equivalent basis with other conventional forage. More work is needed to further explore and quantify the opportunities, limitations, and viability of this technique for broader use. Collection of greenhouse environmental data in this project was uniquely facilitated through the implementation and use of a self-organizing, wirelessly networked, multi-modal sensor system array with remote cell phone data link capability. Applications of wirelessly networked sensing with improved modeling/simulation and other Sandia technologies (e.g., advanced sensing and control, embedded reasoning, modeling and simulation, materials, robotics, etc.) can potentially contribute to significant improvement across a broad range of CEA applications.« less

Intra-seasonal variation in foraging behavior among Adélie penguins (Pygocelis adeliae) breeding at Cape Hallett, Ross Sea, Antarctica

USGS Publications Warehouse

Lyver, P.O.B.; MacLeod, C.J.; Ballard, G.; Karl, B.J.; Barton, K.J.; Adams, J.; Ainley, D.G.; Wilson, P.R.

2011-01-01

We investigated intra-seasonal variation in foraging behavior of chick-rearing Adélie penguins,Pygoscelis adeliae, during two consecutive summers at Cape Hallett, northwestern Ross Sea. Although foraging behavior of this species has been extensively studied throughout the broad continental shelf region of the Ross Sea, this is the first study to report foraging behaviors and habitat affiliations among birds occupying continental slope waters. Continental slope habitat supports the greatest abundances of this species throughout its range, but we lack information about how intra-specific competition for prey might affect foraging and at-sea distribution and how these attributes compare with previous Ross Sea studies. Foraging trips increased in both distance and duration as breeding advanced from guard to crèche stage, but foraging dive depth, dive rates, and vertical dive distances travelled per hour decreased. Consistent with previous studies within slope habitats elsewhere in Antarctic waters, Antarctic krill (Euphausia superba) dominated chick meal composition, but fish increased four-fold from guard to crèche stages. Foraging-, focal-, and core areas all doubled during the crèche stage as individuals shifted distribution in a southeasterly direction away from the coast while simultaneously becoming more widely dispersed (i.e., less spatial overlap among individuals). Intra-specific competition for prey among Adélie penguins appears to influence foraging behavior of this species, even in food webs dominated by Antarctic krill.

Intra-seasonal variation in foraging behavior among Adélie penguins (Pygocelis adeliae) breeding at Cape Hallett, Ross Sea, Antarctica

USGS Publications Warehouse

Lyver, P.O.B.; MacLeod, C.J.; Ballard, G.; Karl, B.J.; Barton, K.J.; Adams, J.; Ainley, D.G.; Wilson, P.R.

2011-01-01

We investigated intra-seasonal variation in foraging behavior of chick-rearing Adélie penguins, Pygoscelis adeliae, during two consecutive summers at Cape Hallett, northwestern Ross Sea. Although foraging behavior of this species has been extensively studied throughout the broad continental shelf region of the Ross Sea, this is the first study to report foraging behaviors and habitat affiliations among birds occupying continental slope waters. Continental slope habitat supports the greatest abundances of this species throughout its range, but we lack information about how intra-specific competition for prey might affect foraging and at-sea distribution and how these attributes compare with previous Ross Sea studies. Foraging trips increased in both distance and duration as breeding advanced from guard to crèche stage, but foraging dive depth, dive rates, and vertical dive distances travelled per hour decreased. Consistent with previous studies within slope habitats elsewhere in Antarctic waters, Antarctic krill (Euphausia superba) dominated chick meal composition, but fish increased four-fold from guard to crèche stages. Foraging-, focal-, and core areas all doubled during the crèche stage as individuals shifted distribution in a southeasterly direction away from the coast while simultaneously becoming more widely dispersed (i.e., less spatial overlap among individuals). Intra-specific competition for prey among Adélie penguins appears to influence foraging behavior of this species, even in food webs dominated by Antarctic krill.

Walrus areas of use in the Chukchi Sea during sparse sea ice cover

USGS Publications Warehouse

Jay, Chadwick V.; Fischbach, Anthony S.; Kochnev, Anatoly A.

2012-01-01

The Pacific walrus Odobenus rosmarus divergens feeds on benthic invertebrates on the continental shelf of the Chukchi and Bering Seas and rests on sea ice between foraging trips. With climate warming, ice-free periods in the Chukchi Sea have increased and are projected to increase further in frequency and duration. We radio-tracked walruses to estimate areas of walrus foraging and occupancy in the Chukchi Sea from June to November of 2008 to 2011, years when sea ice was sparse over the continental shelf in comparison to historical records. The earlier and more extensive sea ice retreat in June to September, and delayed freeze-up of sea ice in October to November, created conditions for walruses to arrive earlier and stay later in the Chukchi Sea than in the past. The lack of sea ice over the continental shelf from September to October caused walruses to forage in nearshore areas instead of offshore areas as in the past. Walruses did not frequent the deep waters of the Arctic Basin when sea ice retreated off the shelf. Walruses foraged in most areas they occupied, and areas of concentrated foraging generally corresponded to regions of high benthic biomass, such as in the northeastern (Hanna Shoal) and southwestern Chukchi Sea. A notable exception was the occurrence of concentrated foraging in a nearshore area of northwestern Alaska that is apparently depauperate in walrus prey. With increasing sea ice loss, it is likely that walruses will increase their use of coastal haul-outs and nearshore foraging areas, with consequences to the population that are yet to be understood.

Common Starlings (Sturnus vulgaris) increasingly select for grazed areas with increasing distance-to-nest.

PubMed

Heldbjerg, Henning; Fox, Anthony D; Thellesen, Peder V; Dalby, Lars; Sunde, Peter

2017-01-01

The abundant and widespread Common Starling (Sturnus vulgaris) is currently declining across much of Europe due to landscape changes caused by agricultural intensification. The proximate mechanisms causing adverse effects to breeding Starlings are unclear, hampering our ability to implement cost-efficient agri-environmental schemes to restore populations to former levels. This study aimed to show how this central foraging farmland bird uses and selects land cover types in general and how use of foraging habitat changes in relation to distance from the nest. We attached GPS-loggers to 17 breeding Starlings at a Danish dairy cattle farm in 2015 and 2016 and analysed their use of different land cover types as a function of distance intervals from the nest and their relative availability. As expected for a central place forager, Starlings increasingly avoided potential foraging areas with greater distance-to-nest: areas ≥ 500 m were selected > 100 times less frequently than areas within 100 m. On average, Starlings selected the land cover category Grazed most frequently, followed by Short Grass, Bare Ground, Meadow and Winter Crops. Starlings compensated for elevated travel costs by showing increasing habitat selection the further they foraged from the nest. Our results highlight the importance of Grazed foraging habitats close to the nest site of breeding Starlings. The ecological capacity of intensively managed farmlands for insectivorous birds like the Starling is decreasing through conversion of the most strongly selected land cover type (Grazed) to the least selected (Winter Crops) which may be further exacerbated through spatial segregation of foraging and breeding habitats.

Common Starlings (Sturnus vulgaris) increasingly select for grazed areas with increasing distance-to-nest

PubMed Central

Fox, Anthony D.; Thellesen, Peder V.; Dalby, Lars; Sunde, Peter

2017-01-01

The abundant and widespread Common Starling (Sturnus vulgaris) is currently declining across much of Europe due to landscape changes caused by agricultural intensification. The proximate mechanisms causing adverse effects to breeding Starlings are unclear, hampering our ability to implement cost-efficient agri-environmental schemes to restore populations to former levels. This study aimed to show how this central foraging farmland bird uses and selects land cover types in general and how use of foraging habitat changes in relation to distance from the nest. We attached GPS-loggers to 17 breeding Starlings at a Danish dairy cattle farm in 2015 and 2016 and analysed their use of different land cover types as a function of distance intervals from the nest and their relative availability. As expected for a central place forager, Starlings increasingly avoided potential foraging areas with greater distance-to-nest: areas ≥ 500 m were selected > 100 times less frequently than areas within 100 m. On average, Starlings selected the land cover category Grazed most frequently, followed by Short Grass, Bare Ground, Meadow and Winter Crops. Starlings compensated for elevated travel costs by showing increasing habitat selection the further they foraged from the nest. Our results highlight the importance of Grazed foraging habitats close to the nest site of breeding Starlings. The ecological capacity of intensively managed farmlands for insectivorous birds like the Starling is decreasing through conversion of the most strongly selected land cover type (Grazed) to the least selected (Winter Crops) which may be further exacerbated through spatial segregation of foraging and breeding habitats. PMID:28771556

Forage Production on Dry Rangelands of Binary Grass-Legume Mixtures at Four Plant Densities

USDA-ARS?s Scientific Manuscript database

Forage production on Western US rangelands can be increased with the right combination of plants. Our objective was to demonstrate the relative forage production advantage of including a legume on dry rangelands. A falcata and rhizomatous alfalfa (medicago sativa L.), alti wildrye [Leymus andustus...

N fertilization for improved forage yields has little impact on nutritive value

USDA-ARS?s Scientific Manuscript database

Applications of soil amendments or fertilizers containing nitrogen are a routine part of most grass forage management strategies, with the primary goal of improving forage yields. But an increase in yield is usually accompanied by a decrease in nutritive value. In order to better evaluate this trade...

Forage yield of grass-alfalfa and grass-forage kochia mixtues on semi-arid rangelands

USDA-ARS?s Scientific Manuscript database

Increased productivity of semiarid western U.S.A. grazing lands is possible with the appropriate plant material combinations. The objective of this study was to compare late summer forage yield of 'Vavilov' Siberian wheatgrass (Agropyron fragile) and 'Mustang' altai wildrye (Leymus angustus) in bin...

Evaluating Agronomic Performance and Investigating Molecular Structure of Drought and Heat Tolerant Wild Alfalfa (Medicago sativa L.) Collection from the Southeastern Turkey.

PubMed

Basbag, Mehmet; Aydin, Ali; Sakiroglu, Muhammet

2017-02-01

Drought is a major stress factor for agricultural production including alfalfa production. One way to counterbalance the yield losses is the introgression of drought tolerant germplasm into breeding programs. As an effort to exploit such germplasm, 16 individual plants were selected from the Southeastern Turkey from their natural habitat and clonally propagated in field trials with an ultimate goal to use the germplasm as parents for releasing a synthetic cultivar. Forage yield and forage quality traits were evaluated and molecular genetic diversity among genotypes were determined using inter simple sequence repeat markers. Genotypes showed a variation from growth habit to yield and quality traits indicating sufficient phenotypic variation for diverse breeding efforts (for grazing or harvesting) and long term selection schemes. A large amount of genetic variation was observed even with a limited number of marker and genotypes. However, no pattern of spatial genetic structure was observed for the scale of the study when genetic variation is linked to the geographic origin. We conclude that ex situ natural variation provides a wealth of germplasm that could be incorporated into breeding programs aiming to improve drought tolerance. We also suggest an extensive collection of seeds/plant tissue from unique plants with desirable traits rather than putting more efforts to create a spatial germplasm sampling efforts in narrow regions.

Men's status and reproductive success in 33 nonindustrial societies: Effects of subsistence, marriage system, and reproductive strategy.

PubMed

von Rueden, Christopher R; Jaeggi, Adrian V

2016-09-27

Social status motivates much of human behavior. However, status may have been a relatively weak target of selection for much of human evolution if ancestral foragers tended to be more egalitarian. We test the "egalitarianism hypothesis" that status has a significantly smaller effect on reproductive success (RS) in foragers compared with nonforagers. We also test between alternative male reproductive strategies, in particular whether reproductive benefits of status are due to lower offspring mortality (parental investment) or increased fertility (mating effort). We performed a phylogenetic multilevel metaanalysis of 288 statistical associations between measures of male status (physical formidability, hunting ability, material wealth, political influence) and RS (mating success, wife quality, fertility, offspring mortality, and number of surviving offspring) from 46 studies in 33 nonindustrial societies. We found a significant overall effect of status on RS (r = 0.19), though this effect was significantly lower than for nonhuman primates (r = 0.80). There was substantial variation due to marriage system and measure of RS, in particular status associated with offspring mortality only in polygynous societies (r = -0.08), and with wife quality only in monogamous societies (r = 0.15). However, the effects of status on RS did not differ significantly by status measure or subsistence type: foraging, horticulture, pastoralism, and agriculture. These results suggest that traits that facilitate status acquisition were not subject to substantially greater selection with domestication of plants and animals, and are part of reproductive strategies that enhance fertility more than offspring well-being.

Use of long-distance migration patterns of an endangered species to inform conservation planning for the world's largest marine protected area.

PubMed

Hays, Graeme C; Mortimer, Jeanne A; Ierodiaconou, Daniel; Esteban, Nicole

2014-12-01

Large marine protected areas (MPAs), each hundreds of thousands of square kilometers, have been set up by governments around the world over the last decade as part of efforts to reduce ocean biodiversity declines, yet their efficacy is hotly debated. The Chagos Archipelago MPA (640,000 km(2) ) (Indian Ocean) lies at the heart of this debate. We conducted the first satellite tracking of a migratory species, the green turtle (Chelonia mydas), within the MPA and assessed the species' use of protected versus unprotected areas. We developed an approach to estimate length of residence within the MPA that may have utility across migratory taxa including tuna and sharks. We recorded the longest ever published migration for an adult cheloniid turtle (3979 km). Seven of 8 tracked individuals migrated to distant foraging grounds, often ≥1000 km outside the MPA. One turtle traveled to foraging grounds within the MPA. Thus, networks of small MPAs, developed synergistically with larger MPAs, may increase the amount of time migrating species spend within protected areas. The MPA will protect turtles during the breeding season and will protect some turtles on their foraging grounds within the MPA and others during the first part of their long-distance postbreeding oceanic migrations. International cooperation will be needed to develop the network of small MPAs needed to supplement the Chagos Archipelago MPA. © 2014 Society for Conservation Biology.

Foraging-Based Enrichment Promotes More Varied Behaviour in Captive Australian Fur Seals (Arctocephalus pusillus doriferus)

PubMed Central

Hocking, David P.; Salverson, Marcia; Evans, Alistair R.

2015-01-01

During wild foraging, Australian fur seals (Arctocephalus pusillus doriferus) encounter many different types of prey in a wide range of scenarios, yet in captive environments they are typically provided with a narrower range of opportunities to display their full repertoire of behaviours. This study aimed to quantitatively explore the effect of foraging-based enrichment on the behaviour and activity patterns displayed by two captive Australian fur seals at Melbourne Zoo, Australia. Food was presented as a scatter in open water, in a free-floating ball device, or in a static box device, with each treatment separated by control trials with no enrichment. Both subjects spent more time interacting with the ball and static box devices than the scatter feed. The total time spent pattern swimming was reduced in the enrichment treatments compared to the controls, while the time spent performing random swimming behaviours increased. There was also a significant increase in the total number of bouts of behaviour performed in all three enrichment treatments compared to controls. Each enrichment method also promoted a different suit of foraging behaviours. Hence, rather than choosing one method, the most effective way to increase the diversity of foraging behaviours, while also increasing variation in general activity patterns, is to provide seals with a wide range of foraging scenarios where food is encountered in different ways. PMID:25946412

Reproductive performance and diving behaviour share a common sea-ice concentration optimum in Adélie penguins (Pygoscelis adeliae).

PubMed

Le Guen, Camille; Kato, Akiko; Raymond, Ben; Barbraud, Christophe; Beaulieu, Michaël; Bost, Charles-André; Delord, Karine; MacIntosh, Andrew J J; Meyer, Xavier; Raclot, Thierry; Sumner, Michael; Takahashi, Akinori; Thiebot, Jean-Baptiste; Ropert-Coudert, Yan

2018-06-29

The Southern Ocean is currently experiencing major environmental changes, including in sea-ice cover. Such changes strongly influence ecosystem structure and functioning and affect the survival and reproduction of predators such as seabirds. These effects are likely mediated by reduced availability of food resources. As such, seabirds are reliable eco-indicators of environmental conditions in the Antarctic region. Here, based on nine years of sea-ice data, we found that the breeding success of Adélie penguins (Pygoscelis adeliae) reaches a peak at intermediate sea-ice cover (ca. 20%). We further examined the effects of sea-ice conditions on the foraging activity of penguins, measured at multiple scales from individual dives to foraging trips. Analysis of temporal organisation of dives, including fractal and bout analyses, revealed an increasingly consistent behaviour during years with extensive sea-ice cover. The relationship between several dive parameters and sea-ice cover in the foraging area appears to be quadratic. In years of low and high sea-ice cover, individuals adjusted their diving effort by generally diving deeper, more frequently and by resting at the surface between dives for shorter periods of time than in years with intermediate sea-ice cover. Our study therefore suggests that sea-ice cover is likely to affect the reproductive performance of Adélie penguins through its effects on foraging behaviour, as breeding success and most diving parameters share a common optimum. Some years, however, deviated from this general trend, suggesting that other factors (e.g. precipitation during the breeding season) might sometimes become preponderant over the sea-ice effects on breeding and foraging performance. Our study highlights the value of monitoring fitness parameters and individual behaviour concomitantly over the long term to better characterize optimal environmental conditions and potential resilience of wildlife. Such an approach is crucial if we want to anticipate the effects of environmental change on Antarctic penguin populations. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Selective food preferences of walleyes of the 1959 year class in Lake Erie

USGS Publications Warehouse

Parsons, John W.

1971-01-01

Stomachs were examined from 1,473 walleyes (Stizostedion vitreum vitreum) of the 1959 year class collected in western Lake Erie from June 1959 to October 1960. In the same period, the relative abundance and lengths of potential forage species were determined from trawl catches. The walleye fed almost entirely on fish. In 1959 the food was dominated first (in June and July) by yellow perch (Perca flavescens) and then, in sequence, by spottail shiners (Notropis hudsonius) and emerald shiners (Notropis atherinoides). In 1960, the walleyes fed mostly on yearling spottail shiners and emerald shiners in the spring and summer but young alewives (Alosa pseudoharengus) became the dominant food in the fall. The length of forage fish increased with the length of walleyes and walleyes of a given length usually ate forage fish within a restricted range of lengths. This size preference was shown by walleyes of the same length in the same and different months. The increased in length of forage fish with length of walleye was not proportionate. Walleyes 2.5 inches long ate forage fish 0.44 times their length whereas walleyes 15.5 inches long ate forage fish only 0.28 times their length. The diet of the walleyes changed according to species and lengths of forage fish available. Since young of several species hatched in different months and grew at different rates, abundance and suitability as forage sometimes changed rapidly.

Implementing unpredictability in feeding enrichment for Malayan sun bears (Helarctos malayanus).

PubMed

Schneider, Marion; Nogge, Gunther; Kolter, Lydia

2014-01-01

Bears in the wild spend large proportions of time in foraging activities. In zoos their time budgets differ markedly from those of their wild counterparts. Feeding enrichment has been documented to increase foraging behavior and to reduce stereotypies. But in general these procedures have no long-term effects and result in habituation. As can be expected by the predictions of the optimal foraging theory, foraging activities are restricted as long as the availability of food is predictable. To quantify the effect of spatial unpredictability, three feeding methods have been designed to stimulate functional foraging behavior in captive Malayan sun bears in the long-term. In order to examine if habituation occurs, the most effective method was tested for 12 consecutive days. Activities of four adult sun bears at the Cologne Zoo were recorded by focal animal recording of foraging behaviors and time sampling of activities for a total of 360 hr. Implementing unpredictability significantly increased the time the bears spent foraging and led to a higher diversity of foraging behaviors. The effects lasted throughout the entire day and no habituation occurred in the course of 12 consecutive days. The study shows how functional species typical behavior in captive Malayan sun bears can be stimulated in the long-term by simulating natural characteristics of food availability. © 2014 Wiley Periodicals, Inc.

Traffic noise reduces foraging efficiency in wild owls

NASA Astrophysics Data System (ADS)

Senzaki, Masayuki; Yamaura, Yuichi; Francis, Clinton D.; Nakamura, Futoshi

2016-08-01

Anthropogenic noise has been increasing globally. Laboratory experiments suggest that noise disrupts foraging behavior across a range of species, but to reveal the full impacts of noise, we must examine the impacts of noise on foraging behavior among species in the wild. Owls are widespread nocturnal top predators and use prey rustling sounds for localizing prey when hunting. We conducted field experiments to examine the effect of traffic noise on owls’ ability to detect prey. Results suggest that foraging efficiency declines with increasing traffic noise levels due to acoustic masking and/or distraction and aversion to traffic noise. Moreover, we estimate that effects of traffic noise on owls’ ability to detect prey reach >120 m from a road, which is larger than the distance estimated from captive studies with bats. Our study provides the first evidence that noise reduces foraging efficiency in wild animals, and highlights the possible pervasive impacts of noise.

Traffic noise reduces foraging efficiency in wild owls.

PubMed

Senzaki, Masayuki; Yamaura, Yuichi; Francis, Clinton D; Nakamura, Futoshi

2016-08-18

Anthropogenic noise has been increasing globally. Laboratory experiments suggest that noise disrupts foraging behavior across a range of species, but to reveal the full impacts of noise, we must examine the impacts of noise on foraging behavior among species in the wild. Owls are widespread nocturnal top predators and use prey rustling sounds for localizing prey when hunting. We conducted field experiments to examine the effect of traffic noise on owls' ability to detect prey. Results suggest that foraging efficiency declines with increasing traffic noise levels due to acoustic masking and/or distraction and aversion to traffic noise. Moreover, we estimate that effects of traffic noise on owls' ability to detect prey reach >120 m from a road, which is larger than the distance estimated from captive studies with bats. Our study provides the first evidence that noise reduces foraging efficiency in wild animals, and highlights the possible pervasive impacts of noise.

Marine foraging ecology influences mercury bioaccumulation in deep-diving northern elephant seals

USGS Publications Warehouse

Peterson, Sarah H.; Ackerman, Joshua T.; Costa, Daniel P.

2015-01-01

Mercury contamination of oceans is prevalent worldwide and methylmercury concentrations in the mesopelagic zone (200–1000 m) are increasing more rapidly than in surface waters. Yet mercury bioaccumulation in mesopelagic predators has been understudied. Northern elephant seals (Mirounga angustirostris) biannually travel thousands of kilometres to forage within coastal and open-ocean regions of the northeast Pacific Ocean. We coupled satellite telemetry, diving behaviour and stable isotopes (carbon and nitrogen) from 77 adult females, and showed that variability among individuals in foraging location, diving depth and δ13C values were correlated with mercury concentrations in blood and muscle. We identified three clusters of foraging strategies, and these resulted in substantially different mercury concentrations: (i) deeper-diving and offshore-foraging seals had the greatest mercury concentrations, (ii) shallower-diving and offshore-foraging seals had intermediate levels, and (iii) coastal and more northerly foraging seals had the lowest mercury concentrations. Additionally, mercury concentrations were lower at the end of the seven-month-long foraging trip (n = 31) than after the two-month- long post-breeding trip (n = 46). Our results indicate that foraging behaviour influences mercury exposure and mesopelagic predators foraging in the northeast Pacific Ocean may be at high risk for mercury bioaccumulation.

Suboptimal foraging behavior: A new perspective on gambling

PubMed Central

Addicott, Merideth A.; Pearson, John M.; Kaiser, Nicole; Platt, Michael L.; McClernon, F. Joseph

2015-01-01

Why do people gamble? Conventional views hold that gambling may be motivated by irrational beliefs, risk-seeking, impulsive temperament, or dysfunction within the same reward circuitry affected by drugs of abuse. An alternate, unexplored perspective is that gambling is an extension of natural foraging behavior to a financial environment. However, when these foraging algorithms are applied to stochastic gambling outcomes, undesirable results may occur. To test this hypothesis, we recruited participants based on their frequency of gambling – yearly (or less), monthly, and weekly – and investigated how gambling frequency related to irrational beliefs, risk-taking/impulsivity, and foraging behavior. We found that increased gambling frequency corresponded to greater gambling-related beliefs, more exploratory choices on an explore/exploit foraging task, and fewer points earned on a patchy foraging task. Gambling-related beliefs negatively related to performance on the patchy foraging task, indicating that individuals with more gambling-related cognitions tended to leave a patch too quickly. This indicates that frequent gamblers have reduced foraging ability to maximize rewards; however, gambling frequency- and by extension, poor foraging ability- was not related to risk-taking or impulsive behavior. These results suggest that gambling reflects the application of a dysfunctional foraging process to financial outcomes. PMID:26191945

Suboptimal foraging behavior: a new perspective on gambling.

PubMed

Addicott, Merideth A; Pearson, John M; Kaiser, Nicole; Platt, Michael L; McClernon, F Joseph

2015-10-01

Why do people gamble? Conventional views hold that gambling may be motivated by irrational beliefs, risk-seeking, impulsive temperament, or dysfunction within the same reward circuitry affected by drugs of abuse. An alternate, unexplored perspective is that gambling is an extension of natural foraging behavior to a financial environment. However, when these foraging algorithms are applied to stochastic gambling outcomes, undesirable results may occur. To test this hypothesis, we recruited participants based on their frequency of gambling-yearly (or less), monthly, and weekly-and investigated how gambling frequency related to irrational beliefs, risk-taking/impulsivity, and foraging behavior. We found that increased gambling frequency corresponded to greater gambling-related beliefs, more exploratory choices on an explore/exploit foraging task, and fewer points earned on a Patchy Foraging Task. Gambling-related beliefs negatively related to performance on the Patchy Foraging Task, indicating that individuals with more gambling-related cognitions tended to leave a patch too quickly. This indicates that frequent gamblers have reduced foraging ability to maximize rewards; however, gambling frequency -and by extension, poor foraging ability- was not related to risk-taking or impulsive behavior. These results suggest that gambling reflects the application of a dysfunctional foraging process to financial outcomes. (c) 2015 APA, all rights reserved).

Breeding success of a marine central place forager in the context of climate change: A modeling approach.

PubMed

Massardier-Galatà, Lauriane; Morinay, Jennifer; Bailleul, Frédéric; Wajnberg, Eric; Guinet, Christophe; Coquillard, Patrick

2017-01-01

In response to climate warming, a southward shift in productive frontal systems serving as the main foraging sites for many top predator species is likely to occur in Subantarctic areas. Central place foragers, such as seabirds and pinnipeds, are thus likely to cope with an increase in the distance between foraging locations and their land-based breeding colonies. Understanding how central place foragers should modify their foraging behavior in response to changes in prey accessibility appears crucial. A spatially explicit individual-based simulation model (Marine Central Place Forager Simulator (MarCPFS)), including bio-energetic components, was built to evaluate effects of possible changes in prey resources accessibility on individual performances and breeding success. The study was calibrated on a particular example: the Antarctic fur seal (Arctocephalus gazella), which alternates between oceanic areas in which females feed and the land-based colony in which they suckle their young over a 120 days rearing period. Our model shows the importance of the distance covered to feed and prey aggregation which appeared to be key factors to which animals are highly sensitive. Memorization and learning abilities also appear to be essential breeding success traits. Females were found to be most successful for intermediate levels of prey aggregation and short distance to the resource, resulting in optimal female body length. Increased distance to resources due to climate warming should hinder pups' growth and survival while female body length should increase.

Breeding success of a marine central place forager in the context of climate change: A modeling approach

PubMed Central

Massardier-Galatà, Lauriane; Morinay, Jennifer; Bailleul, Frédéric; Wajnberg, Eric; Guinet, Christophe; Coquillard, Patrick

2017-01-01

In response to climate warming, a southward shift in productive frontal systems serving as the main foraging sites for many top predator species is likely to occur in Subantarctic areas. Central place foragers, such as seabirds and pinnipeds, are thus likely to cope with an increase in the distance between foraging locations and their land-based breeding colonies. Understanding how central place foragers should modify their foraging behavior in response to changes in prey accessibility appears crucial. A spatially explicit individual-based simulation model (Marine Central Place Forager Simulator (MarCPFS)), including bio-energetic components, was built to evaluate effects of possible changes in prey resources accessibility on individual performances and breeding success. The study was calibrated on a particular example: the Antarctic fur seal (Arctocephalus gazella), which alternates between oceanic areas in which females feed and the land-based colony in which they suckle their young over a 120 days rearing period. Our model shows the importance of the distance covered to feed and prey aggregation which appeared to be key factors to which animals are highly sensitive. Memorization and learning abilities also appear to be essential breeding success traits. Females were found to be most successful for intermediate levels of prey aggregation and short distance to the resource, resulting in optimal female body length. Increased distance to resources due to climate warming should hinder pups’ growth and survival while female body length should increase. PMID:28355282

Foraging and fasting can influence contaminant concentrations in animals: an example with mercury contamination in a free-ranging marine mammal.

PubMed

Peterson, Sarah H; Ackerman, Joshua T; Crocker, Daniel E; Costa, Daniel P

2018-02-14

Large fluctuations in animal body mass in relation to life-history events can influence contaminant concentrations and toxicological risk. We quantified mercury concentrations in adult northern elephant seals ( Mirounga angustirostris ) before and after lengthy at sea foraging trips ( n = 89) or fasting periods on land ( n = 27), and showed that mercury concentrations in blood and muscle changed in response to these events. The highest blood mercury concentrations were observed after the breeding fast, whereas the highest muscle mercury concentrations were observed when seals returned to land to moult. Mean female blood mercury concentrations decreased by 30% across each of the two annual foraging trips, demonstrating a foraging-associated dilution of mercury concentrations as seals gained mass. Blood mercury concentrations increased by 103% and 24% across the breeding and moulting fasts, respectively, demonstrating a fasting-associated concentration of mercury as seals lost mass. In contrast to blood, mercury concentrations in female's muscle increased by 19% during the post-breeding foraging trip and did not change during the post-moulting foraging trip. While fasting, female muscle mercury concentrations increased 26% during breeding, but decreased 14% during moulting. Consequently, regardless of exposure, an animal's contaminant concentration can be markedly influenced by their annual life-history events. © 2018 The Author(s).

Foraging and fasting can influence contaminant concentrations in animals: an example with mercury contamination in a free-ranging marine mammal

USGS Publications Warehouse

Peterson, Sarah; Ackerman, Joshua T.; Crocker, Daniel E.; Costa, Daniel P.

2018-01-01

Large fluctuations in animal body mass in relation to life-history events can influence contaminant concentrations and toxicological risk. We quantified mercury concentrations in adult northern elephant seals (Mirounga angustirostris) before and after lengthy at sea foraging trips (n = 89) or fasting periods on land (n = 27), and showed that mercury concentrations in blood and muscle changed in response to these events. The highest blood mercury concentrations were observed after the breeding fast, whereas the highest muscle mercury concentrations were observed when seals returned to land to moult. Mean female blood mercury concentrations decreased by 30% across each of the two annual foraging trips, demonstrating a foraging-associated dilution of mercury concentrations as seals gained mass. Blood mercury concentrations increased by 103% and 24% across the breeding and moulting fasts, respectively, demonstrating a fasting-associated concentration of mercury as seals lost mass. In contrast to blood, mercury concentrations in female's muscle increased by 19% during the post-breeding foraging trip and did not change during the post-moulting foraging trip. While fasting, female muscle mercury concentrations increased 26% during breeding, but decreased 14% during moulting. Consequently, regardless of exposure, an animal's contaminant concentration can be markedly influenced by their annual life-history events.

Retrospective analysis of bottlenose dolphin foraging: a legacy of anthropogenic ecosystem disturbance

USGS Publications Warehouse

Rossman, Sam; Barros, Nélio B.; Ostrom, Peggy H.; Stricker, Craig A.; Hohn, Aleta A.; Gandhi, Hasand; Wells, Randall S.

2013-01-01

We used stable isotope analysis to investigate the foraging ecology of coastal bottlenose dolphins (Tursiops truncatus) in relation to a series of anthropogenic disturbances. We first demonstrated that stable isotopes are a faithful indicator of habitat use by comparing muscle isotope values to behavioral foraging data from the same individuals. δ13C values increased, while δ34S and δ15N values decreased with the percentage of feeding observations in seagrass habitat. We then utilized stable isotope values of muscle to assess temporal variation in foraging habitat from 1991 to 2010 and collagen from tooth crown tips to assess the time period 1944 to 2007. From 1991 to 2010, δ13C values of muscle decreased while δ34S values increased indicating reduced utilization of seagrass habitat. From 1944 to 1989 δ13C values of the crown tip declined significantly, likely due to a reduction in the coverage of seagrass habitat and δ15N values significantly increased, a trend we attribute to nutrient loading from a rapidly increasing human population. Our results demonstrate the utility of using marine mammal foraging habits to retrospectively assess the extent to which anthropogenic disturbance impacts coastal food webs.

Intercropping Corn with Lablab bean, Velvet Bean, and Scarlet Runner Bean for Forage

USDA-ARS?s Scientific Manuscript database

Low crude protein (CP) concentration in corn (Zea mays L.) forage is its major limitation in dairy rations. This experiment was designed to determine if intercropping corn with climbing beans is a viable option to increase CP concentration in forage rather than purchasing costly CP supplements for ...

Lignin and Fiber digestibility in Caffeic Acid 3-O-Methyltransferase and Caffeoyl CoA 3-O-Methyltransferase Downregulated Alfalfa

USDA-ARS?s Scientific Manuscript database

Alfalfa (Medicago sativa L.) is one of the most important forages in the United States. Increasing alfalfa fiber digestibility would improve forage management and ration formulation flexibility. Currently, growers and breeders rely on near infrared spectroscopy (NIRS) to predict forage quality tra...

Combined use of tri-axial accelerometers and GPS reveals the flexible foraging strategy of a bird in relation to weather conditions

PubMed Central

Rodríguez, Carlos; Dell’Omo, Giacomo; Bustamante, Javier

2017-01-01

Tri-axial accelerometry has proved to be a useful technique to study animal behavior with little direct observation, and also an effective way to measure energy expenditure, allowing a refreshing revisit to optimal foraging theory. This theory predicts that individuals should gain the most energy for the lowest cost in terms of time and energy when foraging, in order to maximize their fitness. However, during a foraging trip, central-place foragers could face different trade-offs during the commuting and searching parts of the trip, influencing behavioral decisions. Using the lesser kestrel (Falco naumanni) as an example we study the time and energy costs of different behaviors during the commuting and searching parts of a foraging trip. Lesser kestrels are small insectivorous falcons that behave as central-place foragers during the breeding season. They can commute by adopting either time-saving flapping flights or energy-saving soaring-gliding flights, and capture prey by using either time-saving active hovering flights or energy-saving perch-hunting. We tracked 6 lesser kestrels using GPS and tri-axial accelerometers during the breeding season. Our results indicate that males devoted more time and energy to flight behaviors than females in agreement with being the sex responsible for food provisioning to the nest. During the commuting flights, kestrels replaced flapping with soaring-gliding flights as solar radiation increased and thermal updrafts got stronger. In the searching part, they replaced perch-hunting with hovering as wind speed increased and they experienced a stronger lift. But also, they increased the use of hovering as air temperature increased, which has a positive influence on the activity level of the preferred prey (large grasshoppers). Kestrels maintained a constant energy expenditure per foraging trip, although flight and hunting strategies changed dramatically with weather conditions, suggesting a fixed energy budget per trip to which they adjusted their commuting and searching strategies in response to weather conditions. PMID:28591181

Seasonal Food Scarcity Prompts Long-Distance Foraging by a Wild Social Bee.

PubMed

Pope, Nathaniel S; Jha, Shalene

2018-01-01

Foraging is an essential process for mobile animals, and its optimization serves as a foundational theory in ecology and evolution; however, drivers of foraging are rarely investigated across landscapes and seasons. Using a common bumblebee species from the western United States (Bombus vosnesenskii), we ask whether seasonal decreases in food resources prompt changes in foraging behavior and space use. We employ a unique integration of population genetic tools and spatially explicit foraging models to estimate foraging distances and rates of patch visitation for wild bumblebee colonies across three study regions and two seasons. By mapping the locations of 669 wild-caught individual foragers, we find substantial variation in colony-level foraging distances, often exhibiting a 60-fold difference within a study region. Our analysis of visitation rates indicates that foragers display a preference for destination patches with high floral cover and forage significantly farther for these patches, but only in the summer, when landscape-level resources are low. Overall, these results indicate that an increasing proportion of long-distance foraging bouts take place in the summer. Because wild bees are pollinators, their foraging dynamics are of urgent concern, given the potential impacts of global change on their movement and services. The behavioral shift toward long-distance foraging with seasonal declines in food resources suggests a novel, phenologically directed approach to landscape-level pollinator conservation and greater consideration of late-season floral resources in pollinator habitat management.

Do wintering Harlequin Ducks forage nocturnally at high latitudes?

USGS Publications Warehouse

Rizzolo, D.J.; Esler, Daniel N.; Roby, D.D.; Jarvis, R.L.

2005-01-01

We monitored radio-tagged Harlequin Ducks (Histrionicus histrionicus) to determine whether nocturnal feeding was part of their foraging strategy during winter in south-central Alaska. Despite attributes of our study site (low ambient temperatures, harsh weather, short day length) and study species (small body size, high daytime foraging rates) that would be expected to favor nocturnal foraging, we found no evidence of nocturnal dive-feeding. Signals from eight radio-tagged Harlequin Ducks never exhibited signal loss due to diving during a total of 780 minutes of nocturnal monitoring. In contrast, the same eight birds exhibited signal loss during 62 ± 7% (SE) of 5-minute diurnal monitoring periods (total of 365 minutes of monitoring). Our results suggest that Harlequin Ducks in south-central Alaska face a stringent time constraint on daytime foraging during midwinter. Harlequin Ducks wintering at high latitudes, therefore, may be particularly sensitive to factors that increase foraging requirements or decrease foraging efficiency.

Foraging Parameters Influencing the Detection and Interpretation of Area-Restricted Search Behaviour in Marine Predators: A Case Study with the Masked Booby

PubMed Central

Sommerfeld, Julia; Kato, Akiko; Ropert-Coudert, Yan; Garthe, Stefan; Hindell, Mark A.

2013-01-01

Identification of Area-restricted search (ARS) behaviour is used to better understand foraging movements and strategies of marine predators. Track-based descriptive analyses are commonly used to detect ARS behaviour, but they may be biased by factors such as foraging trip duration or non-foraging behaviours (i.e. resting on the water). Using first-passage time analysis we tested if (I) daylight resting at the sea surface positions falsely increase the detection of ARS behaviour and (II) short foraging trips are less likely to include ARS behaviour in Masked Boobies Sula dactylatra. We further analysed whether ARS behaviour may be used as a proxy to identify important feeding areas. Depth-acceleration and GPS-loggers were simultaneously deployed on chick-rearing adults to obtain (1) location data every 4 minutes and (2) detailed foraging activity such as diving rates, time spent sitting on the water surface and in flight. In 82% of 50 foraging trips, birds adopted ARS behaviour. In 19.3% of 57 detected ARS zones, birds spent more than 70% of total ARS duration resting on the water, suggesting that these ARS zones were falsely detected. Based on generalized linear mixed models, the probability of detecting false ARS zones was 80%. False ARS zones mostly occurred during short trips in close proximity to the colony, with low or no diving activity. This demonstrates the need to account for resting on the water surface positions in marine animals when determining ARS behaviour based on foraging locations. Dive rates were positively correlated with trip duration and the probability of ARS behaviour increased with increasing number of dives, suggesting that the adoption of ARS behaviour in Masked Boobies is linked to enhanced foraging activity. We conclude that ARS behaviour may be used as a proxy to identify important feeding areas in this species. PMID:23717471

Foraging parameters influencing the detection and interpretation of area-restricted search behaviour in marine predators: a case study with the masked booby.

PubMed

Sommerfeld, Julia; Kato, Akiko; Ropert-Coudert, Yan; Garthe, Stefan; Hindell, Mark A

2013-01-01

Identification of Area-restricted search (ARS) behaviour is used to better understand foraging movements and strategies of marine predators. Track-based descriptive analyses are commonly used to detect ARS behaviour, but they may be biased by factors such as foraging trip duration or non-foraging behaviours (i.e. resting on the water). Using first-passage time analysis we tested if (I) daylight resting at the sea surface positions falsely increase the detection of ARS behaviour and (II) short foraging trips are less likely to include ARS behaviour in Masked Boobies Sula dactylatra. We further analysed whether ARS behaviour may be used as a proxy to identify important feeding areas. Depth-acceleration and GPS-loggers were simultaneously deployed on chick-rearing adults to obtain (1) location data every 4 minutes and (2) detailed foraging activity such as diving rates, time spent sitting on the water surface and in flight. In 82% of 50 foraging trips, birds adopted ARS behaviour. In 19.3% of 57 detected ARS zones, birds spent more than 70% of total ARS duration resting on the water, suggesting that these ARS zones were falsely detected. Based on generalized linear mixed models, the probability of detecting false ARS zones was 80%. False ARS zones mostly occurred during short trips in close proximity to the colony, with low or no diving activity. This demonstrates the need to account for resting on the water surface positions in marine animals when determining ARS behaviour based on foraging locations. Dive rates were positively correlated with trip duration and the probability of ARS behaviour increased with increasing number of dives, suggesting that the adoption of ARS behaviour in Masked Boobies is linked to enhanced foraging activity. We conclude that ARS behaviour may be used as a proxy to identify important feeding areas in this species.

Trapline foraging by pollinators: its ontogeny, economics and possible consequences for plants.

PubMed

Ohashi, Kazuharu; Thomson, James D

2009-06-01

Trapline foraging (repeated sequential visits to a series of feeding locations) has been often observed in pollinators collecting nectar or pollen from flowers. Although field studies on bumble-bees and hummingbirds have clarified fundamental aspects of this behaviour, trapline foraging still poses several difficult questions from the perspectives of both animals and plants. These questions include whether and how traplining improves foraging performance, how animals develop traplines with accumulating foraging experience, and how traplining affects pollen flow or plant reproduction. First, we review our previous work performed by using computer simulations and indoor flight-cage experiments with bumble-bees foraging from arrays of automated feeders. Our findings include the following: (1) traplining benefits foragers that are competing for resources that replenish in a decelerating way, (2) traplining is a learned behaviour that develops over a period of hours and (3) the establishment of traplines could be hampered by spatial configuration of plants such as zigzags. Second, using a simulation model linking pollinator movement and pollen transfer, we consider how service by pollinators with different foraging patterns (searchers or trapliners) would affect pollen flow. Traplining increases mating distance and mate diversity, and reduces 'iterogamy' (self-pollination caused by return visits) at the population level. Furthermore, increased visitation rates can have opposite effects on the reproductive success of a plant, depending on whether the visitors are traplining or searching. Finally, we discuss possible consequences of traplining for plants in the light of new experimental work and modelling. We suggest that trapline foraging by pollinators increases variation among plant populations in genetic diversity, inbreeding depression and contributions of floral traits to plant fitness, which should in turn affect the rates and directions of floral evolution. More theoretical and empirical studies are needed to clarify possible outcomes of such a neglected side of pollination.

Non-cultivated plants present a season-long route of pesticide exposure for honey bees

PubMed Central

Long, Elizabeth Y.; Krupke, Christian H.

2016-01-01

Recent efforts to evaluate the contribution of neonicotinoid insecticides to worldwide pollinator declines have focused on honey bees and the chronic levels of exposure experienced when foraging on crops grown from neonicotinoid-treated seeds. However, few studies address non-crop plants as a potential route of pollinator exposure to neonicotinoid and other insecticides. Here we show that pollen collected by honey bee foragers in maize- and soybean-dominated landscapes is contaminated throughout the growing season with multiple agricultural pesticides, including the neonicotinoids used as seed treatments. Notably, however, the highest levels of contamination in pollen are pyrethroid insecticides targeting mosquitoes and other nuisance pests. Furthermore, pollen from crop plants represents only a tiny fraction of the total diversity of pollen resources used by honey bees in these landscapes, with the principle sources of pollen originating from non-cultivated plants. These findings provide fundamental information about the foraging habits of honey bees in these landscapes. PMID:27240870

Simulation modeling to understand how selective foraging by beaver can drive the structure and function of a willow community

USGS Publications Warehouse

Peinetti, H.R.; Baker, B.W.; Coughenour, M.B.

2009-01-01

Beaver-willow (Castor-Salix) communities are a unique and vital component of healthy wetlands throughout the Holarctic region. Beaver selectively forage willow to provide fresh food, stored winter food, and construction material. The effects of this complex foraging behavior on the structure and function of willow communities is poorly understood. Simulation modeling may help ecologists understand these complex interactions. In this study, a modified version of the SAVANNA ecosystem model was developed to better understand how beaver foraging affects the structure and function of a willow community in a simulated riparian ecosystem in Rocky Mountain National Park, Colorado (RMNP). The model represents willow in terms of plant and stem dynamics and beaver foraging in terms of the quantity and quality of stems cut to meet the energetic and life history requirements of beaver. Given a site where all stems were equally available, the model suggested a simulated beaver family of 2 adults, 2 yearlings, and 2 kits required a minimum of 4 ha of willow (containing about10 stems m-2) to persist in a steady-state condition. Beaver created a willow community where the annual net primary productivity (ANPP) was 2 times higher and plant architecture was more diverse than the willow community without beaver. Beaver foraging created a plant architecture dominated by medium size willow plants, which likely explains how beaver can increase ANPP. Long-term simulations suggested that woody biomass stabilized at similar values even though availability differed greatly at initial condition. Simulations also suggested that willow ANPP increased across a range of beaver densities until beaver became food limited. Thus, selective foraging by beaver increased productivity, decreased biomass, and increased structural heterogeneity in a simulated willow community.

Breeding for genetic improvement of forage plants in relation to increasing animal production with reduced environmental footprint.

PubMed

Kingston-Smith, A H; Marshall, A H; Moorby, J M

2013-03-01

Animal production is a fundamental component of the food supply chain, and with an increasing global population production levels are set to increase. Ruminant animals in particular are valuable in their ability to convert a fibre-rich forage diet into a high-quality protein product for human consumption, although this benefit is offset by inefficiencies in rumen fermentation that contribute to emission of significant quantities of methane and nitrogenous waste. Through co-operation between plant and animal sciences, we can identify how the nutritional requirements of ruminants can be satisfied by high-quality forages for the future. Selective forage plant breeding has supported crop improvement for nearly a century. Early plant breeding programmes were successful in terms of yield gains (4% to 5% per decade), with quality traits becoming increasingly important breeding targets (e.g. enhanced disease resistance and digestibility). Recently, demands for more sustainable production systems have required high yielding, high-quality forages that enable efficient animal production with minimal environmental impact. Achieving this involves considering the entire farm system and identifying opportunities for maximising nutrient use efficiency in both forage and animal components. Forage crops of the future must be able to utilise limited resources (water and nutrients) to maximise production on a limited land area and this may require us to consider alternative plant species to those currently in use. Furthermore, new breeding targets will be identified as the interactions between plants and the animals that consume them become better understood. This will ensure that available resources are targeted at delivering maximum benefits to the animal through enhanced transformation efficiency.

Variation and correlations among European and North American orchardgrass germplasm for herbage yield and nutritive value

USDA-ARS?s Scientific Manuscript database

Efforts to improve water soluble carbohydrate (WSC) concentrations have come to the forefront of perennial forage grass breeding over the last decades. Perennial ryegrass (Lolium perenne L.) breeding has been very successful in developing new cultivars with high WSC and high agronomic performance. ...

Cognitive Performance across the Life Course of Bolivian Forager-Farmers with Limited Schooling

ERIC Educational Resources Information Center

Gurven, Michael; Fuerstenberg, Eric; Trumble, Benjamin; Stieglitz, Jonathan; Beheim, Bret; Davis, Helen; Kaplan, Hillard

2017-01-01

Cognitive performance is characterized by at least two distinct life course trajectories. Many cognitive abilities (e.g., "effortful processing" abilities, including fluid reasoning and processing speed) improve throughout early adolescence and start declining in early adulthood, whereas other abilities (e.g., "crystallized"…

Impact of dietary fiber and physical form on performance of lactating dairy cows.

PubMed

Woodford, J A; Jorgensen, N A; Barrington, G P

1986-04-01

Two trials were conducted to study the effects of forage intake and physical form on lactating cow performance. In trial 1, four cows in a 4 X 4 Latin square were fed long alfalfa hay at 28, 36, 45, and 53% of total dry matter plus concentrate. Total dry matter intake was not affected by forage percent. Total chewing time and milk fat percentage increased linearly with increasing forage consumption. Maximum 4% fat-corrected milk production occurred when diets contained 27% neutral detergent fiber and 18% acid detergent fiber. In trial 2, four cows in a 4 X 4 Latin square were fed diets of chopped alfalfa hay and concentrate in proportions to supply 27.4% total ration neutral detergent fiber. Mean particle length measured with an oscillating screen particle separator of the chopped hay was .26, .46, .64, and .90 cm. Total dry matter and forage dry matter intakes and total chewing were not influenced by forage mean particle length. Mean particle length did not affect actual milk or 4% fat-corrected milk production. Depression of milk fat percentage was prevented when forage mean particle length was greater than or equal .64 cm. Apparent digestibility of dietary constituents and rate of passage of hay and concentrate was not influenced by forage intake or physical form.

Stingless bees (Melipona subnitida) adjust brood production rather than foraging activity in response to changes in pollen stores.

PubMed

Maia-Silva, Camila; Hrncir, Michael; Imperatriz-Fonseca, Vera Lucia; Schorkopf, Dirk Louis P

2016-10-01

Highly eusocial bees (honey bees and stingless bees) sustain their colonies through periods of resource scarcity by food stored within the nest. The protein supply necessary for successful brood production is ensured through adjustments of the colonies' pollen foraging according to the availability of this resource in the environment. In honey bees Apis mellifera, in addition, pollen foraging is regulated through the broods' demand for this resource. Here, we investigated the influence of the colony's pollen store level on pollen foraging and brood production in stingless bees (Melipona subnitida). When pollen was added to the nests, colonies increased their brood production and reduced their pollen foraging within 24 h. On the other hand, when pollen reserves were removed, colonies significantly reduced their brood production. In strong contrast to A. mellifera; however, M. subnitida did not significantly increase its pollen foraging activity under poor pollen store conditions. This difference concerning the regulation of pollen foraging may be due to differences regarding the mechanism of brood provisioning. Honey bees progressively feed young larvae and, consequently, require a constant pollen supply. Stingless bees, by contrast, mass-provision their brood cells and temporary absence of pollen storage will not immediately result in substantial brood loss.

Feeding ecology of arctic-nesting sandpipers during spring migration through the prairie pothole region

USGS Publications Warehouse

Eldridge, J.L.; Krapu, G.L.; Johnson, D.H.

2009-01-01

We evaluated food habits of 4 species of spring-migrant calidrid sandpipers in the Prairie Pothole Region (PPR) of North Dakota. Sandpipers foraged in several wetland classes and fed primarily on aquatic dipterans, mostly larvae, and the midge family Chironomidae was the primary food eaten. Larger sandpiper species foraged in deeper water and took larger larvae than did smaller sandpipers. The diverse wetland habitats that migrant shorebirds use in the PPR suggest a landscape-level approach be applied to wetland conservation efforts. We recommend that managers use livestock grazing and other tools, where applicable, to keep shallow, freshwater wetlands from becoming choked with emergent vegetation limiting chironomid production and preventing shorebird use.

Foraging in subterranean termites (Isoptera: Rhinotermitidae): how do Heterotermes tenuis and Coptotermes gestroi behave when they locate equivalent food resources?

PubMed

Lima, J T; Costa-Leonardo, A M

2014-08-01

A previous research suggests that when subterranean termites locate equivalent food they consume the initial food resource. However, little is known about the movement of foragers among these food sources. For this reason, this study analyzed the feeding behavior of Heterotermes tenuis and Coptotermes gestroi in the presence of equivalent foods. The experimental arenas were composed of a release chamber connected to food chambers. The consumption of each wood block and percentage of the foraging individuals recruited for the food chambers were observed in relation to the total survival rate. The results showed that in the multiple-choice tests, wood block consumptions and the recruitment of individuals did not differ between replicates of each termite species. However, in different tests of tenacity, the chambers with the first food presented higher feeding rates by both H. tenuis and C. gestroi and resulted in a higher recruitment of workers and soldiers. In these conditions, it may be concluded that foragers of either species do not concentrate their efforts on the consumption of only one food resource when they are able to reach multiple cellulosic sources simultaneously. Additionally, the data concerning tenacity tests suggest that there is a chronologic priority of consumption in relation to the discovery of available food sources. Knowledge about the foraging biology of subterranean termites is important for future studies of their feeding behavior, and it is indispensable for improving control strategies.

More milk from forage: Milk production, blood metabolites, and forage intake of dairy cows grazing pasture mixtures and spatially adjacent monocultures.

PubMed

Pembleton, Keith G; Hills, James L; Freeman, Mark J; McLaren, David K; French, Marion; Rawnsley, Richard P

2016-05-01

There is interest in the reincorporation of legumes and forbs into pasture-based dairy production systems as a means of increasing milk production through addressing the nutritive value limitations of grass pastures. The experiments reported in this paper were undertaken to evaluate milk production, blood metabolite concentrations, and forage intake levels of cows grazing either pasture mixtures or spatially adjacent monocultures containing perennial ryegrass (Lolium perenne), white clover (Trifolium repens), and plantain (Plantago lanceolata) compared with cows grazing monocultures of perennial ryegrass. Four replicate herds, each containing 4 spring-calving, cross-bred dairy cows, grazed 4 different forage treatments over the periods of early, mid, and late lactation. Forage treatments were perennial ryegrass monoculture (PRG), a mixture of white clover and plantain (CPM), a mixture of perennial ryegrass, white clover, and plantain (RCPM), and spatially adjacent monocultures (SAM) of perennial ryegrass, white clover, and plantain. Milk volume, milk composition, blood fatty acids, blood β-hydroxybutyrate, blood urea N concentrations, live weight change, and estimated forage intake were monitored over a 5-d response period occurring after acclimation to each of the forage treatments. The acclimation period for the early, mid, and late lactation experiments were 13, 13, and 10 d, respectively. Milk yield (volume and milk protein) increased for cows grazing the RCPM and SAM in the early lactation experiment compared with cows grazing the PRG, whereas in the mid lactation experiment, milk fat increased for the cows grazing the RCPM and SAM when compared with the PRG treatments. Improvements in milk production from grazing the RCPM and SAM treatments are attributed to improved nutritive value (particularly lower neutral detergent fiber concentrations) and a potential increase in forage intake. Pasture mixtures or SAM containing plantain and white clover could be a strategy for alleviating the nutritive limitations of perennial ryegrass monocultures, leading to an increase in milk production for spring calving dairy cows during early and mid lactation. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Matching forage systems with cow size and environment for sustainable cow-calf production in the southern region

USDA-ARS?s Scientific Manuscript database

There has been increased interest in intensification of cow-calf production due to an increasing world population and red meat demand along with reductions in available grazing lands. Intensified production can come about by increasing fertilization, supplementation, or feeding of stored forages, bu...

Partial disturbance of resources foraged by Reticulitermes flavipes.

Treesearch

Thomas Shelton; Gerard Patrick; Terence Wagner

2009-01-01

The introduction of termiticidal baits over 10 years ago has increased interest in the basic foraging behavior of pest termite species. Due to the amount of interference with foraged cellulose material (bait matrices, both treated and untreated) in bait stations as part of some control programs, the following study was initiated to examine the response of termites to...

Partial disturbance of resources foraged by Reticulitermes flavipes

Treesearch

Thomas G. Shelton; Patrick D. Gerard; Terence L. Wagner

2009-01-01

The introduction of termiticidal baits over 10 years ago has increased interest in the basic foraging behavior of pest termite species. Due to the amount of interference with foraged cellulose material (bait matrices, both treated and untreated) in bait stations as part of some control programs, the following study was initiated to examine the response of termites to...

Case study: dairies utilizing ultra-high stocking density grazing in Pennsylvania and New York

USDA-ARS?s Scientific Manuscript database

Ultra-high stocking density (UHSD) grazing has gained interest in the forage industry. Proponents of UHSD emphasize increased forage use efficiency and soil improvement by grazing mature forage with stocking densities up to 560,425 kg ha**-1 of beef cattle on small paddocks with rest periods of up t...

Testosterone and paternal care in East African foragers and pastoralists

PubMed Central

Muller, Martin N.; Marlowe, Frank W.; Bugumba, Revocatus; Ellison, Peter T.

2008-01-01

The ‘challenge hypothesis’ posits that testosterone facilitates reproductive effort (investment in male–male competition and mate-seeking) at the expense of parenting effort (investment in offspring and mates). Multiple studies, primarily in North America, have shown that men in committed relationships, fathers, or both maintain lower levels of testosterone than unpaired men. Data from non-western populations, however, show inconsistent results. We hypothesized that much of this cross-cultural variation can be attributed to differential investment in mating versus parenting effort, even among married fathers. Here, we directly test this idea by comparing two neighbouring Tanzanian groups that exhibit divergent styles of paternal involvement: Hadza foragers and Datoga pastoralists. We predicted that high levels of paternal care by Hadza fathers would be associated with decreased testosterone in comparison with non-fathers, and that no such difference between fathers and non-fathers would be evident in Datoga men, who provide minimal direct paternal care. Twenty-seven Hadza men and 80 Datoga men between the ages of 17 and 60 provided morning and afternoon saliva samples from which testosterone was assayed. Measurements in both populations confirmed these predictions, adding further support to the hypothesis that paternal care is associated with decreased testosterone production in men. PMID:18826936

An integrated approch to the foraging ecology of marine birds and mammals

NASA Astrophysics Data System (ADS)

Croll, Donald A.; Tershy, Bernie R.; Hewitt, Roger P.; Demer, David A.; Fiedler, Paul C.; Smith, Susan E.; Armstrong, Wesley; Popp, Jacqueline M.; Kiekhefer, Thomas; Lopez, Vanesa R.; Urban, Jorge; Gendron, Diane

Birds and mammals are important components of pelagic marine ecosystems, but our knowledge of their foraging ecology is limited. We distinguish six distinct types of data that can be used in various combinations to understand their foraging behavior and ecology. We describe methods that combine concurrent dive recorder deployment, oceanographic sampling, and hydroacoustic surveys to generate hypotheses about interactions between the physical environment and the distribution, abundance, and behavior of pelagic predators and their prey. Our approach is to (1) map the distribution of whales in relation to the distribution of their prey and the physical features of the study area (bottom topography, temperature, and salinity); and (2) measure the foraging behavior and diet of instrumented whales in the context of the fine-scale distribution and composition of their prey and the physical environment. We use this approach to demonstrate a relationship between blue whale distribution, sea surface temperature, and concentrations of their euphausiid prey at different spatial scales offshore of the Channel Islands, California. Blue whale horizontal spatial distribution was correlated with regions of high acoustic backscatter. Blue whale dive depths closely tracked the depth distribution of krill. Net sampling and whale diet revealed that whales fed exclusively upon dense schools of Euphausia pacifica (between 100 and 200 m) and Thysanoessa spinifera (from the surface to 100 m). Whales concentrated foraging efforts upon those dense euphausiid schools that form downstream from an upwelling center in close proximity to regions of steep topographic relief. We propose that (1) the distribution of Balaenoptera whales in the coastal California Current region is defined by their attraction to areas of predictably high prey density; (2) the preferred prey of these whales are several species of euphausiids ( E. pacifica, T. spinifera, and N. simplex) that are abundant in the California Current region; (3) blue whales concentrate their foraging efforts on dense aggregations of euphausiids found at discrete depths in the water column; (4) these localized areas of high euphausiid densities are predictable and sustained by enhanced levels of primary productivity in regions which are located downstream from coastal upwelling centers (indicated by sea surface temperature); (5) topographic breaks in the continental shelf located downstream from these upwelling centers work in concert with euphausiid behavior to collect and maintain large concentrations of euphausiids swarms, and (6) despite seasonal and inter-annual variability, these processes are sufficiently consistent that the distribution of Balaenoptera whales can be predicted.

Effects of selection for honey bee worker reproduction on foraging traits.

PubMed

Oldroyd, Benjamin P; Beekman, Madeleine

2008-03-04

The "reproductive ground plan" hypothesis (RGPH) proposes that reproductive division of labour in social insects had its antecedents in the ancient gene regulatory networks that evolved to regulate the foraging and reproductive phases of their solitary ancestors. Thus, queens express traits that are characteristic of the reproductive phase of solitary insects, whereas workers express traits characteristic of the foraging phase. The RGPH has also been extended to help understand the regulation of age polyethism within the worker caste and more recently to explain differences in the foraging specialisations of individual honey bee workers. Foragers that specialise in collecting proteinaceous pollen are hypothesised to have higher reproductive potential than individuals that preferentially forage for nectar because genes that were ancestrally associated with the reproductive phase are active. We investigated the links between honey bee worker foraging behaviour and reproductive traits by comparing the foraging preferences of a line of workers that has been selected for high rates of worker reproduction with the preferences of wild-type bees. We show that while selection for reproductive behaviour in workers has not altered foraging preferences, the age at onset of foraging of our selected line has been increased. Our findings therefore support the hypothesis that age polyethism is related to the reproductive ground plan, but they cast doubt on recent suggestions that foraging preferences and reproductive traits are pleiotropically linked.

Annual Forages: Influence on Animal Performance and Water/Nutrient Management

USDA-ARS?s Scientific Manuscript database

Annuals can provide short-term grazing between crop rotations or can be interseeded into perennial pastures to increase forage quality and productivity. They provide an opportunity to increase the economic and environmental sustainability of traditional grazing systems. However, to be profitable, an...

Marine foraging ecology influences mercury bioaccumulation in deep-diving northern elephant seals

PubMed Central

Peterson, Sarah H.; Ackerman, Joshua T.; Costa, Daniel P.

2015-01-01

Mercury contamination of oceans is prevalent worldwide and methylmercury concentrations in the mesopelagic zone (200–1000 m) are increasing more rapidly than in surface waters. Yet mercury bioaccumulation in mesopelagic predators has been understudied. Northern elephant seals (Mirounga angustirostris) biannually travel thousands of kilometres to forage within coastal and open-ocean regions of the northeast Pacific Ocean. We coupled satellite telemetry, diving behaviour and stable isotopes (carbon and nitrogen) from 77 adult females, and showed that variability among individuals in foraging location, diving depth and δ13C values were correlated with mercury concentrations in blood and muscle. We identified three clusters of foraging strategies, and these resulted in substantially different mercury concentrations: (i) deeper-diving and offshore-foraging seals had the greatest mercury concentrations, (ii) shallower-diving and offshore-foraging seals had intermediate levels, and (iii) coastal and more northerly foraging seals had the lowest mercury concentrations. Additionally, mercury concentrations were lower at the end of the seven-month-long foraging trip (n = 31) than after the two-month- long post-breeding trip (n = 46). Our results indicate that foraging behaviour influences mercury exposure and mesopelagic predators foraging in the northeast Pacific Ocean may be at high risk for mercury bioaccumulation. PMID:26085591

Understanding the ontogeny of foraging behaviour: insights from combining marine predator bio-logging with satellite-derived oceanography in hidden Markov models.

PubMed

Grecian, W James; Lane, Jude V; Michelot, Théo; Wade, Helen M; Hamer, Keith C

2018-06-01

The development of foraging strategies that enable juveniles to efficiently identify and exploit predictable habitat features is critical for survival and long-term fitness. In the marine environment, meso- and sub-mesoscale features such as oceanographic fronts offer a visible cue to enhanced foraging conditions, but how individuals learn to identify these features is a mystery. In this study, we investigate age-related differences in the fine-scale foraging behaviour of adult (aged ≥ 5 years) and immature (aged 2-4 years) northern gannets Morus bassanus Using high-resolution GPS-loggers, we reveal that adults have a much narrower foraging distribution than immature birds and much higher individual foraging site fidelity. By conditioning the transition probabilities of a hidden Markov model on satellite-derived measures of frontal activity, we then demonstrate that adults show a stronger response to frontal activity than immature birds, and are more likely to commence foraging behaviour as frontal intensity increases. Together, these results indicate that adult gannets are more proficient foragers than immatures, supporting the hypothesis that foraging specializations are learned during individual exploratory behaviour in early life. Such memory-based individual foraging strategies may also explain the extended period of immaturity observed in gannets and many other long-lived species. © 2018 The Authors.

Adaptive collective foraging in groups with conflicting nutritional needs

PubMed Central

Senior, Alistair M.; Lihoreau, Mathieu; Charleston, Michael A.; Buhl, Jerome; Raubenheimer, David; Simpson, Stephen J.

2016-01-01

Collective foraging, based on positive feedback and quorum responses, is believed to improve the foraging efficiency of animals. Nutritional models suggest that social information transfer increases the ability of foragers with closely aligned nutritional needs to find nutrients and maintain a balanced diet. However, whether or not collective foraging is adaptive in a heterogeneous group composed of individuals with differing nutritional needs is virtually unexplored. Here we develop an evolutionary agent-based model using concepts of nutritional ecology to address this knowledge gap. Our aim was to evaluate how collective foraging, mediated by social retention on foods, can improve nutrient balancing in individuals with different requirements. The model suggests that in groups where inter-individual nutritional needs are unimodally distributed, high levels of collective foraging yield optimal individual fitness by reducing search times that result from moving between nutritionally imbalanced foods. However, where nutritional needs are highly bimodal (e.g. where the requirements of males and females differ) collective foraging is selected against, leading to group fission. In this case, additional mechanisms such as assortative interactions can coevolve to allow collective foraging by subgroups of individuals with aligned requirements. Our findings indicate that collective foraging is an efficient strategy for nutrient regulation in animals inhabiting complex nutritional environments and exhibiting a range of social forms. PMID:27152206

Pollen foraging: learning a complex motor skill by bumblebees (Bombus terrestris)

NASA Astrophysics Data System (ADS)

Raine, Nigel E.; Chittka, Lars

2007-06-01

To investigate how bumblebees (Bombus terrestris) learn the complex motor skills involved in pollen foraging, we observed naïve workers foraging on arrays of nectarless poppy flowers (Papaver rhoeas) in a greenhouse. Foraging skills were quantified by measuring the pollen load collected during each foraging bout and relating this to the number of flowers visited and bout duration on two consecutive days. The pollen standing crop (PSC) in each flower decreased drastically from 0530 to 0900 hours. Therefore, we related foraging performance to the changing levels of pollen available (per flower) and found that collection rate increased over the course of four consecutive foraging bouts (comprising between 277 and 354 individual flower visits), suggesting that learning to forage for pollen represents a substantial time investment for individual foragers. The pollen collection rate and size of pollen loads collected at the start of day 2 were markedly lower than at the end of day 1, suggesting that components of pollen foraging behaviour could be subject to imperfect overnight retention. Our results suggest that learning the necessary motor skills to collect pollen effectively from morphologically simple flowers takes three times as many visits as learning how to handle the most morphologically complex flowers to extract nectar, potentially explaining why bees are more specialised in their choice of pollen flowers.

Impact of the 2015 El Niño-Southern Oscillation on the Abundance and Foraging Habits of Guadalupe Fur Seals and California Sea Lions from the San Benito Archipelago, Mexico.

PubMed

Elorriaga-Verplancken, Fernando R; Sierra-Rodríguez, Gema E; Rosales-Nanduca, Hiram; Acevedo-Whitehouse, Karina; Sandoval-Sierra, Julieta

2016-01-01

The abundance of California sea lions (Zalophus californianus) (CSLs) and Guadalupe fur seals (Arctocephalus philippii townsendi) (GFSs) from the San Benito Archipelago (SBA) was determined through nine monthly surveys in 2014-2015. Assessment of their foraging habits was examined based on the isotopic analysis of pups (maternal indicators) (SIAR/SIBER-R). Environmental variability between 2014 and 2015 was also analyzed, in terms of sea surface temperature (SST) and chlorophyll (Chl-a) concentration. Both otariids reached their highest abundance in July of both years; however, relative to 2014, the 2015 survey showed a 59.7% decline in the total GFS abundance and a 42.9% decrease of GFS pups, while total CSL abundance decreased 52.0% and CSL pup presence decreased in 61.7%. All monthly surveys for both otariids showed a similar trend (>50% decrease in 2015). Compared to 2014, the 2015 GFSs isotopic niche was three times larger (2.0 in 2015, 0.6 in 2014) and the δ13C was significantly lower. CSLs also showed significantly lower δ13C and higher δ15N in 2015. Interannual segregation was greater for CSLs, and their pup body mass was also significantly lower during the 2015 breeding season (mean = 8.7 kg) than in the same season of 2014 (mean = 9.9 kg). The decrease in δ13C for both otariids reflected a more oceanic foraging; most likely associated with the decline in primary productivity in surrounding areas to the SBA, related to a higher SST caused by the 2015 ENSO, with a subsequent increase in foraging effort. These would explain the fewer observed individuals on land, especially pups, which showed diminished body condition (CSLs). This study highlights the importance of marine mammals as sentinel species that respond dynamically to changes in environment, providing valuable information on the effect of ENSO on pinnipeds in Mexican waters.

Impact of the 2015 El Niño-Southern Oscillation on the Abundance and Foraging Habits of Guadalupe Fur Seals and California Sea Lions from the San Benito Archipelago, Mexico

PubMed Central

Elorriaga-Verplancken, Fernando R.; Sierra-Rodríguez, Gema E.; Rosales-Nanduca, Hiram; Acevedo-Whitehouse, Karina; Sandoval-Sierra, Julieta

2016-01-01

The abundance of California sea lions (Zalophus californianus) (CSLs) and Guadalupe fur seals (Arctocephalus philippii townsendi) (GFSs) from the San Benito Archipelago (SBA) was determined through nine monthly surveys in 2014–2015. Assessment of their foraging habits was examined based on the isotopic analysis of pups (maternal indicators) (SIAR/SIBER-R). Environmental variability between 2014 and 2015 was also analyzed, in terms of sea surface temperature (SST) and chlorophyll (Chl-a) concentration. Both otariids reached their highest abundance in July of both years; however, relative to 2014, the 2015 survey showed a 59.7% decline in the total GFS abundance and a 42.9% decrease of GFS pups, while total CSL abundance decreased 52.0% and CSL pup presence decreased in 61.7%. All monthly surveys for both otariids showed a similar trend (>50% decrease in 2015). Compared to 2014, the 2015 GFSs isotopic niche was three times larger (2.0 in 2015, 0.6 in 2014) and the δ13C was significantly lower. CSLs also showed significantly lower δ13C and higher δ15N in 2015. Interannual segregation was greater for CSLs, and their pup body mass was also significantly lower during the 2015 breeding season (mean = 8.7 kg) than in the same season of 2014 (mean = 9.9 kg). The decrease in δ13C for both otariids reflected a more oceanic foraging; most likely associated with the decline in primary productivity in surrounding areas to the SBA, related to a higher SST caused by the 2015 ENSO, with a subsequent increase in foraging effort. These would explain the fewer observed individuals on land, especially pups, which showed diminished body condition (CSLs). This study highlights the importance of marine mammals as sentinel species that respond dynamically to changes in environment, providing valuable information on the effect of ENSO on pinnipeds in Mexican waters. PMID:27171473

Modelling food and population dynamics in honey bee colonies.

PubMed

Khoury, David S; Barron, Andrew B; Myerscough, Mary R

2013-01-01

Honey bees (Apis mellifera) are increasingly in demand as pollinators for various key agricultural food crops, but globally honey bee populations are in decline, and honey bee colony failure rates have increased. This scenario highlights a need to understand the conditions in which colonies flourish and in which colonies fail. To aid this investigation we present a compartment model of bee population dynamics to explore how food availability and bee death rates interact to determine colony growth and development. Our model uses simple differential equations to represent the transitions of eggs laid by the queen to brood, then hive bees and finally forager bees, and the process of social inhibition that regulates the rate at which hive bees begin to forage. We assume that food availability can influence both the number of brood successfully reared to adulthood and the rate at which bees transition from hive duties to foraging. The model predicts complex interactions between food availability and forager death rates in shaping colony fate. Low death rates and high food availability results in stable bee populations at equilibrium (with population size strongly determined by forager death rate) but consistently increasing food reserves. At higher death rates food stores in a colony settle at a finite equilibrium reflecting the balance of food collection and food use. When forager death rates exceed a critical threshold the colony fails but residual food remains. Our model presents a simple mathematical framework for exploring the interactions of food and forager mortality on colony fate, and provides the mathematical basis for more involved simulation models of hive performance.

Foraging modality and plasticity in foraging traits determine the strength of competitive interactions among carnivorous plants, spiders and toads.

PubMed

Jennings, David E; Krupa, James J; Rohr, Jason R

2016-07-01

Foraging modalities (e.g. passive, sit-and-wait, active) and traits are plastic in some species, but the extent to which this plasticity affects interspecific competition remains unclear. Using a long-term laboratory mesocosm experiment, we quantified competition strength and the plasticity of foraging traits in a guild of generalist predators of arthropods with a range of foraging modalities. Each mesocosm contained eight passively foraging pink sundews, and we employed an experimental design where treatments were the presence or absence of a sit-and-wait foraging spider and actively foraging toad crossed with five levels of prey abundance. We hypothesized that actively foraging toads would outcompete the other species at low prey abundance, but that spiders and sundews would exhibit plasticity in foraging traits to compensate for strong competition when prey were limited. Results generally supported our hypotheses. Toads had a greater effect on sundews at low prey abundances, and toad presence caused spiders to locate webs higher above the ground. Additionally, the closer large spider webs were to the ground, the greater the trichome densities produced by sundews. Also, spider webs were larger with than without toads and as sundew numbers increased, and these effects were more prominent as resources became limited. Finally, spiders negatively affected toad growth only at low prey abundance. These findings highlight the long-term importance of foraging modality and plasticity of foraging traits in determining the strength of competition within and across taxonomic kingdoms. Future research should assess whether plasticity in foraging traits helps to maintain coexistence within this guild and whether foraging modality can be used as a trait to reliably predict the strength of competitive interactions. © 2016 The Authors. Journal of Animal Ecology © 2016 British Ecological Society.

A roadmap for research on crassulacean acid metabolism (CAM) to enhance sustainable food and bioenergy production in a hotter, drier world

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Xiaohan; Cushman, John C.; Borland, Anne M.

Crassulacean acid metabolism (CAM) is a specialized mode of photosynthesis that features nocturnal CO₂ uptake, facilitates increased water-use efficiency (WUE), and enables CAM plants to inhabit water-limited environments such as semi-arid deserts or seasonally dry forests. Human population growth and global climate change now present challenges for agricultural production systems to increase food, feed, forage, fiber, and fuel production. One approach to meet these challenges is to increase reliance on CAM crops, such as Agave and Opuntia, for biomass production on semi-arid, abandoned, marginal, or degraded agricultural lands. Major research efforts are now underway to assess the productivity of CAMmore » crop species and to harness the WUE of CAM by engineering this pathway into existing food and bioenergy crops. An improved understanding of CAM gained through intensive and expanded research efforts has potential for high returns on research investment in the foreseeable future. To help realize the potential of sustainable dryland agricultural systems, it is necessary to address scientific questions related to the genomic features, regulatory mechanisms, and evolution of CAM; CAM-into-C3 engineering; and the production of CAM crops. Answering these questions requires collaborative efforts to build infrastructure for CAM model systems, field trials, mutant collections, and data management.« less

A roadmap for research on crassulacean acid metabolism (CAM) to enhance sustainable food and bioenergy production in a hotter, drier world

DOE PAGES

Yang, Xiaohan; Cushman, John C.; Borland, Anne M.; ...

2015-07-07

Crassulacean acid metabolism (CAM) is a specialized mode of photosynthesis that features nocturnal CO₂ uptake, facilitates increased water-use efficiency (WUE), and enables CAM plants to inhabit water-limited environments such as semi-arid deserts or seasonally dry forests. Human population growth and global climate change now present challenges for agricultural production systems to increase food, feed, forage, fiber, and fuel production. One approach to meet these challenges is to increase reliance on CAM crops, such as Agave and Opuntia, for biomass production on semi-arid, abandoned, marginal, or degraded agricultural lands. Major research efforts are now underway to assess the productivity of CAMmore » crop species and to harness the WUE of CAM by engineering this pathway into existing food and bioenergy crops. An improved understanding of CAM gained through intensive and expanded research efforts has potential for high returns on research investment in the foreseeable future. To help realize the potential of sustainable dryland agricultural systems, it is necessary to address scientific questions related to the genomic features, regulatory mechanisms, and evolution of CAM; CAM-into-C3 engineering; and the production of CAM crops. Answering these questions requires collaborative efforts to build infrastructure for CAM model systems, field trials, mutant collections, and data management.« less

Flexibility in the parental effort of an Arctic-breeding seabird

USGS Publications Warehouse

Harding, A.M.A.; Kitaysky, A.S.; Hall, M.E.; Welcker, J.; Karnovsky, N.J.; Talbot, S.L.; Hamer, K.C.; Gremillet, D.

2009-01-01

Parental investment strategies are considered to represent a trade-off between the benefits of investment in current offspring and costs to future reproduction. Due to their high residual reproductive value, long-lived organisms are predicted to be more reluctant to increase parental effort. 2. We tested the hypothesis that breeding little auks (Alle alle) have a fixed level of reproductive investment, and thus reduce parental effort when costs associated with reproduction increase. 3. To test this hypothesis we experimentally increased the flight costs of breeding little auks via feather clipping. In 2005 we examined changes in the condition of manipulated parents, of the mates of manipulated parents, and of their chick as direct measures of change in parental resource allocation between self-maintenance and current reproduction. In 2007 we increased sample sizes to determine whether there was a physiological cost (elevated corticosterone, CORT) associated with the manipulation. 4. We found that: (i) clipped birds and their mates lost more body mass than controls, but there was no difference in mass loss between members of a pair; (ii) clipped birds had higher CORT levels than control birds; (iii) there were no inter-annual differences in body mass and CORT levels between clipped individuals and their mates at recapture, and (iv) chicks with a clipped parent had lower peak and fledging mass, and higher CORT levels than control chicks in both years. 5. Contrary to our hypothesis, the reduction in body mass of partners to clipped birds suggests that little auks can increase parental effort to some extent. Nonetheless, the lower fledging mass and higher CORT of chicks with a clipped parent indicates provisioning rates may not have been fully maintained. 6. As predicted by life-history theory, there may be a threshold to the additional reproductive costs breeders will accept, with parents prioritizing self-maintenance over increased provisioning effort when foraging costs become too high. ?? 2008 British Ecological Society.

A predator equalizes rate of capture of a schooling prey in a patchy environment.

PubMed

Vijayan, Sundararaj; Kotler, Burt P; Abramsky, Zvika

2017-05-01

Prey individuals are often distributed heterogeneously in the environment, and their abundances and relative availabilities vary among patches. A foraging predator should maximize energetic gains by selectively choosing patches with higher prey density. However, catching behaviorally responsive and group-forming prey in patchy environments can be a challenge for predators. First, they have to identify the profitable patches, and second, they must manage the prey's sophisticated anti-predator behavior. Thus, the forager and its prey have to continuously adjust their behavior to that of their opponent. Given these conditions, the foraging predator's behavior should be dynamic with time in terms of foraging effort and prey capture rates across different patches. Theoretically, the allocation of its time among patches of behaviorally responsive prey should be such that it equalizes its prey capture rates across patches through time. We tested this prediction in a model system containing a predator (little egret) and group-forming prey (common gold fish) in two sets of experiments in which (1) patches (pools) contained equal numbers of prey, or in which (2) patches contained unequal densities of prey. The egret equalized the prey capture rate through time in both equal and different density experiments. Copyright © 2017 Elsevier B.V. All rights reserved.

Prey state shapes the effects of temporal variation in predation risk

PubMed Central

Matassa, Catherine M.; Trussell, Geoffrey C.

2014-01-01

The ecological impacts of predation risk are influenced by how prey allocate foraging effort across periods of safety and danger. Foraging decisions depend on current danger, but also on the larger temporal, spatial or energetic context in which prey manage their risks of predation and starvation. Using a rocky intertidal food chain, we examined the responses of starved and fed prey (Nucella lapillus dogwhelks) to different temporal patterns of risk from predatory crabs (Carcinus maenas). Prey foraging activity declined during periods of danger, but as dangerous periods became longer, prey state altered the magnitude of risk effects on prey foraging and growth, with likely consequences for community structure (trait-mediated indirect effects on basal resources, Mytilus edulis mussels), prey fitness and trophic energy transfer. Because risk is inherently variable over time and space, our results suggest that non-consumptive predator effects may be most pronounced in productive systems where prey can build energy reserves during periods of safety and then burn these reserves as ‘trophic heat’ during extended periods of danger. Understanding the interaction between behavioural (energy gain) and physiological (energy use) responses to risk may illuminate the context dependency of trait-mediated trophic cascades and help explain variation in food chain length. PMID:25339716

Enemy deterrence in the recruitment strategy of a termite: Soldier-organized foraging in Nasutitermes costalis

PubMed Central

Traniello, James F. A.

1981-01-01

The nasute soldiers of the neotropical termite Nasutitermes costalis function as scouts by exploring new terrain for food in advance of the worker caste and regulate foraging activity by laying trails composed of sternal gland pheromone. Additional soldiers are at first recruited in large numbers, and subsequently workers appear as the pheromone concentration increases. The role of the nasutes in the organization of foraging is extremely unusual for the soldier caste in social insects and appears to be a component of a foraging/defense system that controls the recruitment of foragers and effectively deters attacks by ants, the most fierce and important predators of termites. PMID:16592995

Foraging Ecology of Fall-Migrating Shorebirds in the Illinois River Valley

PubMed Central

Smith, Randolph V.; Stafford, Joshua D.; Yetter, Aaron P.; Horath, Michelle M.; Hine, Christopher S.; Hoover, Jeffery P.

2012-01-01

Populations of many shorebird species appear to be declining in North America, and food resources at stopover habitats may limit migratory bird populations. We investigated body condition of, and foraging habitat and diet selection by 4 species of shorebirds in the central Illinois River valley during fall migrations 2007 and 2008 (Killdeer [Charadrius vociferus], Least Sandpiper [Calidris minutilla], Pectoral Sandpiper [Calidris melanotos], and Lesser Yellowlegs [Tringa flavipes]). All species except Killdeer were in good to excellent condition, based on size-corrected body mass and fat scores. Shorebird diets were dominated by invertebrate taxa from Orders Diptera and Coleoptera. Additionally, Isopoda, Hemiptera, Hirudinea, Nematoda, and Cyprinodontiformes contribution to diets varied by shorebird species and year. We evaluated diet and foraging habitat selection by comparing aggregate percent dry mass of food items in shorebird diets and core samples from foraging substrates. Invertebrate abundances at shorebird collection sites and random sites were generally similar, indicating that birds did not select foraging patches within wetlands based on invertebrate abundance. Conversely, we found considerable evidence for selection of some diet items within particular foraging sites, and consistent avoidance of Oligochaeta. We suspect the diet selectivity we observed was a function of overall invertebrate biomass (51.2±4.4 [SE] kg/ha; dry mass) at our study sites, which was greater than estimates reported in most other food selection studies. Diet selectivity in shorebirds may follow tenants of optimal foraging theory; that is, at low food abundances shorebirds forage opportunistically, with the likelihood of selectivity increasing as food availability increases. Nonetheless, relationships between the abundance, availability, and consumption of Oligochaetes for and by waterbirds should be the focus of future research, because estimates of foraging carrying capacity would need to be revised downward if Oligochaetes are truly avoided or unavailable for consumption. PMID:23028795

Honey bee forager thoracic temperature inside the nest is tuned to broad-scale differences in recruitment motivation.

PubMed

Sadler, Nik; Nieh, James C

2011-02-01

Insects that regulate flight muscle temperatures serve as crucial pollinators in a broad range of ecosystems, in part because they forage over a wide span of temperatures. Honey bees are a classic example and maintain their thoracic muscles at temperatures (T(th)) tuned to the caloric benefits of floral resources. Using infrared thermography, we tested the hypothesis that forager motivation to recruit nestmates for a food source is positively correlated with T(th). We trained bees to a sucrose feeder located 5-100 m from the nest. Recruiting foragers had a significantly higher average T(th) (2.7°C higher) when returning from 2.5 mol l(-1) sucrose (65% w/w) than when returning from 1.0 mol l(-1) sucrose (31% w/w). Foragers exhibited significantly larger thermal fluctuations the longer they spent inside the nest between foraging trips. The difference between maximum and minimum temperatures during a nest visit (T(range)) increased with total duration of the nest visit (0.7°C increase per additional min spent inside the nest). Bees that recruited nestmates (waggle or round danced) were significantly warmer, with a 1.4-1.5 times higher ΔT(th) (difference between T(th) and nest ambient air temperature) than bees who tremble danced or simply walked on the nest floor without recruiting between foraging bouts. However, recruiter T(th) was not correlated with finer-scale measures of motivation: the number of waggle dance circuits or waggle dance return phase duration. These results support the hypothesis that forager T(th) within the nest is correlated to broad-scale differences in foraging motivation.

Effects of tidal cycles on shorebird distribution and foraging behaviour in a coastal tropical wetland: Insights for carrying capacity assessment

NASA Astrophysics Data System (ADS)

Fonseca, Juanita; Basso, Enzo; Serrano, David; Navedo, Juan G.

2017-11-01

Wetland loss has driven negative effects on biodiversity by a reduction in potential available habitats, directly impacting wetland-dependent species such as migratory shorebirds. At coastal areas where tidal cycles can restrict food access, the degree to which density of foraging birds is mediated by conspecific abundance or by the available areas is crucial to understanding patterns of bird distribution and wetland carrying capacity. We used the bathymetry of two sectors modeled with two numerical matrices to determine the availability of intertidal foraging areas in relation to tidal level (spring and neap tides), and this information was used to estimate shorebird density and foraging activity throughout the low-tide cycle in a tropical coastal lagoon in northwestern Mexico. Relative to spring tides, an 80% reduction in available foraging areas occurred during neap tides. Overall shorebird abundance was significantly reduced during neap tide periods, with differences between species. Densities of shorebirds increased during neap tides, particularly in one sector, and remained similar throughout the low-tide period (i.e. 4 h) either during spring or neap tides. Time spent foraging was consistently lower during neap-tides relative to spring-tides, especially for Long-billed curlew (44% reduction), Willet (37% reduction) and Black-necked stilt (29% reduction). These decreases in foraging activity when available habitats became reduced can hamper the opportunities of migratory shorebirds to reach their daily energy requirements to survive during the non-breeding season. This study shows that when intertidal habitats are severely reduced an important fraction of shorebird populations would probably be forced to find alternative areas to forage or increase foraging time during the night. Serving an essential function as top-predators, these results can have important implications on carrying capacity assessment for shorebirds at coastal wetlands.

Mercury bioaccumulation and risk to three waterbird foraging guilds is influenced by foraging ecology and breeding stage

USGS Publications Warehouse

Eagles-Smith, Collin A.; Ackerman, Joshua T.; de la Cruz, S.E.W.; Takekawa, John Y.

2009-01-01

We evaluated mercury (Hg) in five waterbird species representing three foraging guilds in San Francisco Bay, CA. Fish-eating birds (Forster's and Caspian terns) had the highest Hg concentrations in thier tissues, but concentrations in an invertebrate-foraging shorebird (black-necked stilt) were also elevated. Foraging habitat was important for Hg exposure as illustrated by within-guild differences, where species more associated with marshes and salt ponds had higher concentrations than those more associated with open-bay and tidal mudflats. Importantly, Hg concentrations increased with time spent in the estuary. Surf scoter concentrations tripled over six months, whereas Forster's terns showed an up to 5-fold increase between estuary arrival and breeding. Breeding waterbirds were at elevated risk of Hg-induced reproductive impairment, particularly Forster's terns, in which 48% of breeding birds were at high risk due to their Hg??levels. Our results highlight the importance of habitat and exposure timing, in addition to trophic position, on waterbird Hg bioaccumulation and risk.

Collective Response of Leaf-Cutting Ants to the Effects of Wind on Foraging Activity.

PubMed

Alma, Andrea Marina; Farji-Brener, Alejandro G; Elizalde, Luciana

2016-11-01

One advantage of sociality is to mitigate environmental restrictions through collective behavior. Here we document a colony-level response of leaf-cutting ants to wind, an environmental factor that impedes foraging. Given that larger ants adhere more strongly to the substrate, increasing forager size in windy conditions should reduce the negative effect of wind. We tested this idea for Acromyrmex lobicornis in windy regions of Patagonia. We examined (1) whether the fraction of larger ants versus smaller ants increased in windy conditions and (2) whether the effect of wind on the ants' movement was lower for larger ants. The size-frequency distribution of foragers was skewed more toward larger ants in nature under more windy conditions. Under windy conditions in the field, the mobility of smaller ants was more reduced than that of larger ants. The change toward larger foragers in windy conditions reduced the negative effect of wind by 32%, illustrating how a social organism can collectively mitigate the adverse effects of the environment.

Forage kochia and Russian wildrye potential for rehabilitating Gardner's saltbush ecosystems degraded by halogeton

USDA-ARS?s Scientific Manuscript database

Gardner saltbush ecosystems are increasingly being invaded by halogeton (Halogeton glomeratus), which is extremely competitive and believed to increase soil surface salinity making it difficult to establish other desired plants. This study evaluated the ability of forage kochia (Kochia prostrata), ...

Burrowing and foraging activity of marsh crabs under different inundation regimes

EPA Science Inventory

New England salt marshes are susceptible to degradation and habitat loss as a result of increased periods of inundation as sea levels rise. Increased inundation may exacerbate marsh degradation that can result from crab burrowing and foraging. Most studies to date have focused on...

Economic impacts of increasing seasonal precipitation variation on southeast Wyoming cow-calf enterprises

USDA-ARS?s Scientific Manuscript database

Economic impacts of predicted increases in precipitation variability on cow-calf enterprises, through influences of precipitation on both forage and cattle productivity, are needed by land managers for risk management strategies. Here we utilize existing forage production and cattle performance data...

Managing uncertainty: information and insurance under the risk of starvation.

PubMed Central

Dall, Sasha R X; Johnstone, Rufus A

2002-01-01

In an uncertain world, animals face both unexpected opportunities and danger. Such outcomes can select for two potential strategies: collecting information to reduce uncertainty, or insuring against it. We investigate the relative value of information and insurance (energy reserves) under starvation risk by offering model foragers a choice between constant and varying food sources over finite foraging bouts. We show that sampling the variable option (choosing it when it is not expected to be good) should decline both with lower reserves and late in foraging bouts; in order to be able to reap the reduction in uncertainty associated with exploiting a variable resource effectively, foragers must be able to afford and compensate for an initial increase in the risk of an energetic shortfall associated with choosing the option when it is bad. Consequently, expected exploitation of the varying option increases as it becomes less variable, and when the overall risk of energetic shortfall is reduced. In addition, little activity on the variable alternative is expected until reserves are built up early in a foraging bout. This indicates that gathering information is a luxury while insurance is a necessity, at least when foraging on stochastic and variable food under the risk of starvation. PMID:12495509

Comment on “Marine plastic debris emits a keystone infochemical for olfactory foraging seabirds” by Savoca et al.

PubMed Central

Dell’Ariccia, Gaia; Phillips, Richard A.; van Franeker, Jan A.; Gaidet, Nicolas; Catry, Paulo; Granadeiro, José P.; Ryan, Peter G.; Bonadonna, Francesco

2017-01-01

In their recent paper, Savoca and collaborators (2016) showed that plastic debris in the ocean may acquire a dimethyl sulfide (DMS) signature from biofouling developing on their surface. According to them, DMS emission may represent an olfactory trap for foraging seabirds, which explains patterns of plastic ingestion among procellariiform seabirds. This hypothesis is appealing, but some of the data that Savoca et al. used to support their claim are questionable, resulting in a misclassification of species, as well as other decisions regarding the variables to include in their models. Furthermore, with their focus on a single lifestyle trait (nesting habit) of dubious relevance for explaining plastic ingestion, Savoca et al. neglect the opportunity to explore other factors that might provide better ecological insight. Finally, we are deeply concerned by the conservation policy recommendation proposed by Savoca et al.—to increase antifouling properties of consumer plastics—which constitutes a substantial environmental risk and delivers the wrong message to decision-makers. The reduction of plastic consumption, waste prevention, and proactive reuse through a circular economy should be at the heart of policy recommendations for future mitigation efforts. PMID:28782012

Comment on "Marine plastic debris emits a keystone infochemical for olfactory foraging seabirds" by Savoca et al.

PubMed

Dell'Ariccia, Gaia; Phillips, Richard A; van Franeker, Jan A; Gaidet, Nicolas; Catry, Paulo; Granadeiro, José P; Ryan, Peter G; Bonadonna, Francesco

2017-06-01

In their recent paper, Savoca and collaborators (2016) showed that plastic debris in the ocean may acquire a dimethyl sulfide (DMS) signature from biofouling developing on their surface. According to them, DMS emission may represent an olfactory trap for foraging seabirds, which explains patterns of plastic ingestion among procellariiform seabirds. This hypothesis is appealing, but some of the data that Savoca et al. used to support their claim are questionable, resulting in a misclassification of species, as well as other decisions regarding the variables to include in their models. Furthermore, with their focus on a single lifestyle trait (nesting habit) of dubious relevance for explaining plastic ingestion, Savoca et al. neglect the opportunity to explore other factors that might provide better ecological insight. Finally, we are deeply concerned by the conservation policy recommendation proposed by Savoca et al. -to increase antifouling properties of consumer plastics-which constitutes a substantial environmental risk and delivers the wrong message to decision-makers. The reduction of plastic consumption, waste prevention, and proactive reuse through a circular economy should be at the heart of policy recommendations for future mitigation efforts.

Evidence of trapline foraging in honeybees.

PubMed

Buatois, Alexis; Lihoreau, Mathieu

2016-08-15

Central-place foragers exploiting floral resources often use multi-destination routes (traplines) to maximise their foraging efficiency. Recent studies on bumblebees have showed how solitary foragers can learn traplines, minimising travel costs between multiple replenishing feeding locations. Here we demonstrate a similar routing strategy in the honeybee (Apis mellifera), a major pollinator known to recruit nestmates to discovered food resources. Individual honeybees trained to collect sucrose solution from four artificial flowers arranged within 10 m of the hive location developed repeatable visitation sequences both in the laboratory and in the field. A 10-fold increase of between-flower distances considerably intensified this routing behaviour, with bees establishing more stable and more efficient routes at larger spatial scales. In these advanced social insects, trapline foraging may complement cooperative foraging for exploiting food resources near the hive (where dance recruitment is not used) or when resources are not large enough to sustain multiple foragers at once. © 2016. Published by The Company of Biologists Ltd.

Rapid behavioral maturation accelerates failure of stressed honey bee colonies

PubMed Central

Perry, Clint J.; Myerscough, Mary R.; Barron, Andrew B.

2015-01-01

Many complex factors have been linked to the recent marked increase in honey bee colony failure, including pests and pathogens, agrochemicals, and nutritional stressors. It remains unclear, however, why colonies frequently react to stressors by losing almost their entire adult bee population in a short time, resulting in a colony population collapse. Here we examine the social dynamics underlying such dramatic colony failure. Bees respond to many stressors by foraging earlier in life. We manipulated the demography of experimental colonies to induce precocious foraging in bees and used radio tag tracking to examine the consequences of precocious foraging for their performance. Precocious foragers completed far fewer foraging trips in their life, and had a higher risk of death in their first flights. We constructed a demographic model to explore how this individual reaction of bees to stress might impact colony performance. In the model, when forager death rates were chronically elevated, an increasingly younger forager force caused a positive feedback that dramatically accelerated terminal population decline in the colony. This resulted in a breakdown in division of labor and loss of the adult population, leaving only brood, food, and few adults in the hive. This study explains the social processes that drive rapid depopulation of a colony, and we explore possible strategies to prevent colony failure. Understanding the process of colony failure helps identify the most effective strategies to improve colony resilience. PMID:25675508

Waggle Dance Distances as Integrative Indicators of Seasonal Foraging Challenges

PubMed Central

Couvillon, Margaret J.; Schürch, Roger; Ratnieks, Francis L. W.

2014-01-01

Even as demand for their services increases, honey bees (Apis mellifera) and other pollinating insects continue to decline in Europe and North America. Honey bees face many challenges, including an issue generally affecting wildlife: landscape changes have reduced flower-rich areas. One way to help is therefore to supplement with flowers, but when would this be most beneficial? We use the waggle dance, a unique behaviour in which a successful forager communicates to nestmates the location of visited flowers, to make a 2-year survey of food availability. We “eavesdropped” on 5097 dances to track seasonal changes in foraging, as indicated by the distance to which the bees as economic foragers will recruit, over a representative rural-urban landscape. In year 3, we determined nectar sugar concentration. We found that mean foraging distance/area significantly increase from springs (493 m, 0.8 km2) to summers (2156 m, 15.2 km2), even though nectar is not better quality, before decreasing in autumns (1275 m, 5.1 km2). As bees will not forage at long distances unnecessarily, this suggests summer is the most challenging season, with bees utilizing an area 22 and 6 times greater than spring or autumn. Our study demonstrates that dancing bees as indicators can provide information relevant to helping them, and, in particular, can show the months when additional forage would be most valuable. PMID:24695678

Effects of Climate Change on Range Forage Production in the San Francisco Bay Area

PubMed Central

Chaplin-Kramer, Rebecca; George, Melvin R.

2013-01-01

The San Francisco Bay Area in California, USA is a highly heterogeneous region in climate, topography, and habitats, as well as in its political and economic interests. Successful conservation strategies must consider various current and future competing demands for the land, and should pay special attention to livestock grazing, the dominant non-urban land-use. The main objective of this study was to predict changes in rangeland forage production in response to changes in temperature and precipitation projected by downscaled output from global climate models. Daily temperature and precipitation data generated by four climate models were used as input variables for an existing rangeland forage production model (linear regression) for California’s annual rangelands and projected on 244 12 km x 12 km grid cells for eight Bay Area counties. Climate model projections suggest that forage production in Bay Area rangelands may be enhanced by future conditions in most years, at least in terms of peak standing crop. However, the timing of production is as important as its peak, and altered precipitation patterns could mean delayed germination, resulting in shorter growing seasons and longer periods of inadequate forage quality. An increase in the frequency of extremely dry years also increases the uncertainty of forage availability. These shifts in forage production will affect the economic viability and conservation strategies for rangelands in the San Francisco Bay Area. PMID:23472102

Rapid behavioral maturation accelerates failure of stressed honey bee colonies.

PubMed

Perry, Clint J; Søvik, Eirik; Myerscough, Mary R; Barron, Andrew B

2015-03-17

Many complex factors have been linked to the recent marked increase in honey bee colony failure, including pests and pathogens, agrochemicals, and nutritional stressors. It remains unclear, however, why colonies frequently react to stressors by losing almost their entire adult bee population in a short time, resulting in a colony population collapse. Here we examine the social dynamics underlying such dramatic colony failure. Bees respond to many stressors by foraging earlier in life. We manipulated the demography of experimental colonies to induce precocious foraging in bees and used radio tag tracking to examine the consequences of precocious foraging for their performance. Precocious foragers completed far fewer foraging trips in their life, and had a higher risk of death in their first flights. We constructed a demographic model to explore how this individual reaction of bees to stress might impact colony performance. In the model, when forager death rates were chronically elevated, an increasingly younger forager force caused a positive feedback that dramatically accelerated terminal population decline in the colony. This resulted in a breakdown in division of labor and loss of the adult population, leaving only brood, food, and few adults in the hive. This study explains the social processes that drive rapid depopulation of a colony, and we explore possible strategies to prevent colony failure. Understanding the process of colony failure helps identify the most effective strategies to improve colony resilience.

Over-Expression of Arabidopsis EDT1 Gene Confers Drought Tolerance in Alfalfa (Medicago sativa L.)

PubMed Central

Zheng, Guangshun; Fan, Cunying; Di, Shaokang; Wang, Xuemin; Xiang, Chengbin; Pang, Yongzhen

2017-01-01

Alfalfa (Medicago sativa L.) is an important legume forage crop with great economic value. However, as the growth of alfalfa is seriously affected by an inadequate supply of water, drought is probably the major abiotic environmental factor that most severely affects alfalfa production worldwide. In an effort to enhance alfalfa drought tolerance, we transformed the Arabidopsis Enhanced Drought Tolerance 1 (AtEDT1) gene into alfalfa via Agrobacterium-mediated transformation. Compared with wild type plants, drought stress treatment resulted in higher survival rates and biomass, but reduced water loss rates in the transgenic plants. Furthermore, transgenic alfalfa plants had increased stomatal size, but reduced stomatal density, and these stomatal changes contributed greatly to reduced water loss from leaves. Importantly, transgenic alfalfa plants exhibited larger root systems with larger root lengths, root weight, and root diameters than wild type plants. The transgenic alfalfa plants had reduced membrane permeability and malondialdehyde content, but higher soluble sugar and proline content, higher superoxide dismutase activity, higher chlorophyll content, enhanced expression of drought-responsive genes, as compared with wild type plants. Notably, transgenic alfalfa plants grew better in a 2-year field trial and showed enhanced growth performance with increased biomass yield. All of our morphological, physiological, and molecular analyses demonstrated that the ectopic expression of AtEDT1 improved growth and enhanced drought tolerance in alfalfa. Our study provides alfalfa germplasm for use in forage improvement programs, and may help to increase alfalfa production in arid lands. PMID:29326737

Over-Expression of Arabidopsis EDT1 Gene Confers Drought Tolerance in Alfalfa (Medicago sativa L.).

PubMed

Zheng, Guangshun; Fan, Cunying; Di, Shaokang; Wang, Xuemin; Xiang, Chengbin; Pang, Yongzhen

2017-01-01

Alfalfa ( Medicago sativa L.) is an important legume forage crop with great economic value. However, as the growth of alfalfa is seriously affected by an inadequate supply of water, drought is probably the major abiotic environmental factor that most severely affects alfalfa production worldwide. In an effort to enhance alfalfa drought tolerance, we transformed the Arabidopsis Enhanced Drought Tolerance 1 ( AtEDT1 ) gene into alfalfa via Agrobacterium -mediated transformation. Compared with wild type plants, drought stress treatment resulted in higher survival rates and biomass, but reduced water loss rates in the transgenic plants. Furthermore, transgenic alfalfa plants had increased stomatal size, but reduced stomatal density, and these stomatal changes contributed greatly to reduced water loss from leaves. Importantly, transgenic alfalfa plants exhibited larger root systems with larger root lengths, root weight, and root diameters than wild type plants. The transgenic alfalfa plants had reduced membrane permeability and malondialdehyde content, but higher soluble sugar and proline content, higher superoxide dismutase activity, higher chlorophyll content, enhanced expression of drought-responsive genes, as compared with wild type plants. Notably, transgenic alfalfa plants grew better in a 2-year field trial and showed enhanced growth performance with increased biomass yield. All of our morphological, physiological, and molecular analyses demonstrated that the ectopic expression of AtEDT1 improved growth and enhanced drought tolerance in alfalfa. Our study provides alfalfa germplasm for use in forage improvement programs, and may help to increase alfalfa production in arid lands.

The status of the Willow and Pacific-slope flycatchers in northwestern California and southern Oregon

Treesearch

C. John Ralph; K. Hollinger

2003-01-01

The Willow (Empidonax traillii) and Pacific-slope (E. dificilis) flycatchers are generally similar in their morphology and foraging, but differ in their habitat and population dynamics. Through a concentration of constant-effort mist-netting stations, we documented the movements and composition of populations over a relatively...

Honeybee economics: optimisation of foraging in a variable world.

PubMed

Stabentheiner, Anton; Kovac, Helmut

2016-06-20

In honeybees fast and efficient exploitation of nectar and pollen sources is achieved by persistent endothermy throughout the foraging cycle, which means extremely high energy costs. The need for food promotes maximisation of the intake rate, and the high costs call for energetic optimisation. Experiments on how honeybees resolve this conflict have to consider that foraging takes place in a variable environment concerning microclimate and food quality and availability. Here we report, in simultaneous measurements of energy costs, gains, and intake rate and efficiency, how honeybee foragers manage this challenge in their highly variable environment. If possible, during unlimited sucrose flow, they follow an 'investment-guided' ('time is honey') economic strategy promising increased returns. They maximise net intake rate by investing both own heat production and solar heat to increase body temperature to a level which guarantees a high suction velocity. They switch to an 'economizing' ('save the honey') optimisation of energetic efficiency if the intake rate is restricted by the food source when an increased body temperature would not guarantee a high intake rate. With this flexible and graded change between economic strategies honeybees can do both maximise colony intake rate and optimise foraging efficiency in reaction to environmental variation.

Men’s status and reproductive success in 33 nonindustrial societies: Effects of subsistence, marriage system, and reproductive strategy

PubMed Central

von Rueden, Christopher R.; Jaeggi, Adrian V.

2016-01-01

Social status motivates much of human behavior. However, status may have been a relatively weak target of selection for much of human evolution if ancestral foragers tended to be more egalitarian. We test the “egalitarianism hypothesis” that status has a significantly smaller effect on reproductive success (RS) in foragers compared with nonforagers. We also test between alternative male reproductive strategies, in particular whether reproductive benefits of status are due to lower offspring mortality (parental investment) or increased fertility (mating effort). We performed a phylogenetic multilevel metaanalysis of 288 statistical associations between measures of male status (physical formidability, hunting ability, material wealth, political influence) and RS (mating success, wife quality, fertility, offspring mortality, and number of surviving offspring) from 46 studies in 33 nonindustrial societies. We found a significant overall effect of status on RS (r = 0.19), though this effect was significantly lower than for nonhuman primates (r = 0.80). There was substantial variation due to marriage system and measure of RS, in particular status associated with offspring mortality only in polygynous societies (r = −0.08), and with wife quality only in monogamous societies (r = 0.15). However, the effects of status on RS did not differ significantly by status measure or subsistence type: foraging, horticulture, pastoralism, and agriculture. These results suggest that traits that facilitate status acquisition were not subject to substantially greater selection with domestication of plants and animals, and are part of reproductive strategies that enhance fertility more than offspring well-being. PMID:27601650

To dare or not to dare? Risk management by owls in a predator-prey foraging game.

PubMed

Embar, Keren; Raveh, Ashael; Burns, Darren; Kotler, Burt P

2014-07-01

In a foraging game, predators must catch elusive prey while avoiding injury. Predators manage their hunting success with behavioral tools such as habitat selection, time allocation, and perhaps daring-the willingness to risk injury to increase hunting success. A predator's level of daring should be state dependent: the hungrier it is, the more it should be willing to risk injury to better capture prey. We ask, in a foraging game, will a hungry predator be more willing to risk injury while hunting? We performed an experiment in an outdoor vivarium in which barn owls (Tyto alba) were allowed to hunt Allenby's gerbils (Gerbillus andersoni allenbyi) from a choice of safe and risky patches. Owls were either well fed or hungry, representing the high and low state, respectively. We quantified the owls' patch use behavior. We predicted that hungry owls would be more daring and allocate more time to the risky patches. Owls preferred to hunt in the safe patches. This indicates that owls manage risk of injury by avoiding the risky patches. Hungry owls doubled their attacks on gerbils, but directed the added effort mostly toward the safe patch and the safer, open areas in the risky patch. Thus, owls dared by performing a risky action-the attack maneuver-more times, but only in the safest places-the open areas. We conclude that daring can be used to manage risk of injury and owls implement it strategically, in ways we did not foresee, to minimize risk of injury while maximizing hunting success.

Energetic Optimisation of Foraging Honeybees: Flexible Change of Strategies in Response to Environmental Challenges

PubMed Central

Stabentheiner, Anton; Kovac, Helmut

2014-01-01

Heterothermic insects like honeybees, foraging in a variable environment, face the challenge of keeping their body temperature high to enable immediate flight and to promote fast exploitation of resources. Because of their small size they have to cope with an enormous heat loss and, therefore, high costs of thermoregulation. This calls for energetic optimisation which may be achieved by different strategies. An ‘economizing’ strategy would be to reduce energetic investment whenever possible, for example by using external heat from the sun for thermoregulation. An ‘investment-guided’ strategy, by contrast, would be to invest additional heat production or external heat gain to optimize physiological parameters like body temperature which promise increased energetic returns. Here we show how honeybees balance these strategies in response to changes of their local microclimate. In a novel approach of simultaneous measurement of respiration and body temperature foragers displayed a flexible strategy of thermoregulatory and energetic management. While foraging in shade on an artificial flower they did not save energy with increasing ambient temperature as expected but acted according to an ‘investment-guided’ strategy, keeping the energy turnover at a high level (∼56–69 mW). This increased thorax temperature and speeded up foraging as ambient temperature increased. Solar heat was invested to increase thorax temperature at low ambient temperature (‘investment-guided’ strategy) but to save energy at high temperature (‘economizing’ strategy), leading to energy savings per stay of ∼18–76% in sunshine. This flexible economic strategy minimized costs of foraging, and optimized energetic efficiency in response to broad variation of environmental conditions. PMID:25162211

The Main Suppressing Factors of Dry Forage Intake in Large-type Goats

PubMed Central

Van Thang, Tran; Sunagawa, Katsunori; Nagamine, Itsuki; Kishi, Tetsuya; Ogura, Go

2012-01-01

In large-type goats that were fed on dry forage twice daily, dry forage intake was markedly suppressed after 40 min of feeding had elapsed. The objective of this study was to determine whether or not marked decreases in dry forage intake after 40 min of feeding are mainly caused by the two factors, that is, ruminal distension and increased plasma osmolality induced thirst produced by dry forage feeding. Six large-type male esophageal- and ruminal-fistulated goats (crossbred Japanese Saanen/Nubian, aged 2 to 6 years, weighing 85.1±4.89 kg) were used in two experiments. The animals were fed ad libitum a diet of roughly crushed alfalfa hay cubes for 2 h from 10:00 to 12:00 am during two experiments. Water was withheld during feeding in both experiments but was available for a period of 30 min after completion of the 2 h feeding period. In experiment 1, saliva lost via the esophageal fistula was replenished by an intraruminal infusion of artificial parotid saliva (RIAPS) in sham feeding conditions (SFC) control, and the treatment was maintained under normal feeding conditions (NFC). In experiment 2, a RIAPS and non-insertion of a balloon (RIAPS-NB) control was conducted in the same manner as the SFC control of experiment 1. The intraruminal infusion of hypertonic solution and insertion of a balloon (RIHS-IB) treatment was carried out simultaneously to reproduce the effects of changing salt content and ruminal distension due to feed entering the rumen. The results of experiment 1 showed that due to the effects of multiple dry forage suppressing factors when feed boluses entered the rumen, eating rates in the NFC treatment decreased (p<0.05) after 40 min of feeding and cumulative dry forage intake for the 2 h feeding period reduced to 43.8% of the SFC control (p<0.01). The results of experiment 2 indicated that due to the two suppressing factors of ruminal distension and increased plasma osmolality induced thirst, eating rates in the RIHS-IB treatment were, as observed under NFC, reduced (p<0.05) and cumulative dry forage intake for the 2 h feeding period decreased to 34.0% of the RIAPS-NB control (p<0.01). The combined effects of ruminal distension and increased plasma osmolality accounted for 77.5% of the suppression of dry forage intake 40 min after the start of dry forage feeding. The results indicate that ruminal distension and increased plasma osmolality induced thirst are the main factors in the suppression of dry forage intake in large-type goats. PMID:25049572

Soil erosion studies in buffelgrass pastures

Treesearch

Diego Valdez-Zamudio; D. Phillip Guertin

2000-01-01

The introduction of exotic grasses in native rangelands to increase the production of forage has been a good alternative for the cattle industry in North America. Different studies have demonstrated that buffelgrass (Cenchrus ciliaris L.), a plant introduced from Africa, increases the annual green forage production approximately three times in comparison to production...

An energy-circuit population model for great egrets (Ardea alba) at Lake Okeechobee, Florida, U.S.A

USGS Publications Warehouse

Smith, Jeff P.

1997-01-01

I simulated the annual population cycles of Great Egrets (Ardea alba) at Lake Okeechobee, Florida, to provide a framework for evaluating the local population dynamics of nesting and foraging wading birds. The external forcing functions were solar energy, minimum air temperature, water depth, surface-water drying rate, and season. Solar input controlled the production of prey at moderate to high lake stages, but water area exerted primary control during a two-year drought. Modeling prey production as a linear function of water area resulted in underestimation of prey density during the drought, suggesting that prey organisms maintained high fecundity while concentrated in submerged vegetation at the lakeward fringe of the littoral zone. Simulation confirmed that large influxes of wading birds during the drought were the combined result of a regional refuge response and the availability of concentrated prey. Modeling immigration and emigration as primarily functions of the surface-water drying rate, rather than lake stage, resulted in a closer match of observed and simulated population trends for foraging birds, suggesting that the pattern of surface-water fluctuations was a more important factor than water depth. Simulation indicated an abrupt-threshold response rather than a linear association between foraging efficiency and low temperatures, which reduce activity levels of forage fishes. Great Egret breeder recruitment is primarily a function of prey availability, climate, and hydrologic trends, but simulation confirmed the concurrent involvement of a seasonal or physiological-readiness factor. An attractor function driven by high winter lake stages was necessary to reproduce observed patterns of breeder recruitment, suggesting that Great Egrets initiate nesting based on environmental cues that lead to peak food availability when nestlings are present. Poor correspondence of reproductive effort and nest productivity suggested that the drought compromised the birds' predictive abilities. The need to model breeder recruitment as a function of a maximum rate rather than the size of the local foraging population suggested that birds may nest on the lake even though on-lake foraging conditions are poor. Simulated and observed estimates of egg and hatching production did not match, suggesting that the causes of failure during incubation were complex or more localized than could be accounted for with lakewide hydrologic and climatic data. A forced increase in prey consumption of 12% was necessary to reproduce observed, high levels of nest productivity in 1990, which corresponded to the finding that panhandled fish constituted 10–12% of the biomass fed to Great Egret nestlings that year.

Cumulative Effects of Foraging Behavior and Social Dominance on Brain Development in a Facultatively Social Bee (Ceratina australensis).

PubMed

Rehan, Sandra M; Bulova, Susan J; O'Donnell, Sean

2015-01-01

In social insects, both task performance (foraging) and dominance are associated with increased brain investment, particularly in the mushroom bodies. Whether and how these factors interact is unknown. Here we present data on a system where task performance and social behavior can be analyzed simultaneously: the small carpenter bee Ceratina australensis. We show that foraging and dominance have separate and combined cumulative effects on mushroom body calyx investment. Female C. australensis nest solitarily and socially in the same populations at the same time. Social colonies comprise two sisters: the social primary, which monopolizes foraging and reproduction, and the social secondary, which is neither a forager nor reproductive but rather remains at the nest as a guard. We compare the brains of solitary females that forage and reproduce but do not engage in social interactions with those of social individuals while controlling for age, reproductive status, and foraging experience. Mushroom body calyx volume was positively correlated with wing wear, a proxy for foraging experience. We also found that, although total brain volume did not vary among reproductive strategies (solitary vs. social nesters), socially dominant primaries had larger mushroom body calyx volumes (corrected for both brain and body size variation) than solitary females; socially subordinate secondaries (that are neither dominant nor foragers) had the least-developed mushroom body calyces. These data demonstrate that sociality itself does not explain mushroom body volume; however, achieving and maintaining dominance status in a group was associated with mushroom body calyx enlargement. Dominance and foraging effects were cumulative; dominant social primary foragers had larger mushroom body volumes than solitary foragers, and solitary foragers had larger mushroom body volumes than nonforaging social secondary guards. This is the first evidence for cumulative effects on brain development by dominance and task performance.

Predation Risk Perception, Food Density and Conspecific Cues Shape Foraging Decisions in a Tropical Lizard

PubMed Central

Kolbe, Jason J.

2015-01-01

When foraging, animals can maximize their fitness if they are able to tailor their foraging decisions to current environmental conditions. When making foraging decisions, individuals need to assess the benefits of foraging while accounting for the potential risks of being captured by a predator. However, whether and how different factors interact to shape these decisions is not yet well understood, especially in individual foragers. Here we present a standardized set of manipulative field experiments in the form of foraging assays in the tropical lizard Anolis cristatellus in Puerto Rico. We presented male lizards with foraging opportunities to test how the presence of conspecifics, predation-risk perception, the abundance of food, and interactions among these factors determines the outcome of foraging decisions. In Experiment 1, anoles foraged faster when food was scarce and other conspecifics were present near the feeding tray, while they took longer to feed when food was abundant and when no conspecifics were present. These results suggest that foraging decisions in anoles are the result of a complex process in which individuals assess predation risk by using information from conspecific individuals while taking into account food abundance. In Experiment 2, a simulated increase in predation risk (i.e., distance to the feeding tray) confirmed the relevance of risk perception by showing that the use of available perches is strongly correlated with the latency to feed. We found Puerto Rican crested anoles integrate instantaneous ecological information about food abundance, conspecific activity and predation risk, and adjust their foraging behavior accordingly. PMID:26384236

Ant Foraging As an Indicator of Tropical Dry Forest Restoration.

PubMed

Hernández-Flores, J; Osorio-Beristain, M; Martínez-Garza, C

2016-08-01

Variation in foraging behavior may indicate differences in food availability and allow assessment of restoration actions. Ants are prominent bioindicators used in assessing ecological responses to disturbance. However, behavioral data have been poorly incorporated as an index. The foraging performance of red harvester ants was quantified in order to evaluate the success of a restoration ecology experiment in the tropical dry forest of Sierra de Huautla, Morelos, in central Mexico. Foraging performance by granivorous, Pogonomyrmex barbatus, ants was diminished after 6 and 8 years of cattle grazing and wood harvest were excluded as part of a restoration experiment in a highly degraded biome. Despite investing more time in foraging, ant colonies in exclusion plots showed lower foraging success and acquired less seed biomass than colonies in control plots. In line with the predictions of optimal foraging theory, in restored plots where ant foraging performance was poor, ants harvested a higher diversity of seeds. Reduced foraging success and increased harvest of non-preferred foods in exclusion plots were likely due to the growth of herbaceous vegetation, which impedes travel by foragers. Moreover, by 8 years of exclusion, 37% of nests in exclusion plots had disappeared compared to 0% of nests in control plots. Ants' foraging success and behavior were sensitive to changes in habitat quality due to the plant successional process triggered by a restoration intervention. This study spotlights on the utility of animal foraging behavior in the evaluation of habitat restoration programs. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Caffeinated forage tricks honeybees into increasing foraging and recruitment behaviors.

PubMed

Couvillon, Margaret J; Al Toufailia, Hasan; Butterfield, Thomas M; Schrell, Felix; Ratnieks, Francis L W; Schürch, Roger

2015-11-02

In pollination, plants provide food reward to pollinators who in turn enhance plant reproduction by transferring pollen, making the relationship largely cooperative; however, because the interests of plants and pollinators do not always align, there exists the potential for conflict, where it may benefit both to cheat the other [1, 2]. Plants may even resort to chemistry: caffeine, a naturally occurring, bitter-tasting, pharmacologically active secondary compound whose main purpose is to detract herbivores, is also found in lower concentrations in the nectar of some plants, even though nectar, unlike leaves, is made to be consumed by pollinators. [corrected]. A recent laboratory study showed that caffeine may lead to efficient and effective foraging by aiding honeybee memory of a learned olfactory association [4], suggesting that caffeine may enhance bee reward perception. However, without field data, the wider ecological significance of caffeinated nectar remains difficult to interpret. Here we demonstrate in the field that caffeine generates significant individual- and colony-level effects in free-flying worker honeybees. Compared to a control, a sucrose solution with field-realistic doses of caffeine caused honeybees to significantly increase their foraging frequency, waggle dancing probability and frequency, and persistency and specificity to the forage location, resulting in a quadrupling of colony-level recruitment. An agent-based model also demonstrates how caffeine-enhanced foraging may reduce honey storage. Overall, caffeine causes bees to overestimate forage quality, tempting the colony into sub-optimal foraging strategies, which makes the relationship between pollinator and plant less mutualistic and more exploitative. VIDEO ABSTRACT. Copyright © 2015 Elsevier Ltd. All rights reserved.

Assessing Honey Bee (Hymenoptera: Apidae) Foraging Populations and the Potential Impact of Pesticides on Eight U.S. Crops

PubMed Central

Frazier, Maryann T.; Mullin, Chris A.; Frazier, Jim L.; Ashcraft, Sara A.; Leslie, Tim W.; Mussen, Eric C.; Drummond, Frank A.

2015-01-01

Beekeepers who use honey bees (Apis mellifera L.) for crop pollination services, or have colonies making honey on or in close proximity to agricultural crops, are concerned about the reductions of colony foragers and ultimate weakening of their colonies. Pesticide exposure is a potential factor in the loss of foragers. During 2009–2010, we assessed changes in the field force populations of 9–10 colonies at one location per crop on each of the eight crops by counting departing foragers leaving colonies at regular intervals during the respective crop blooming periods. The number of frames of adult bees was counted before and after bloom period. For pesticide analysis, we collected dead and dying bees near the hives, returning foragers, crop flowers, trapped pollen, and corn-flowers associated with the cotton crop. The number of departing foragers changed over time in all crops except almonds; general patterns in foraging activity included declines (cotton), noticeable peaks and declines (alfalfa, blueberries, cotton, corn, and pumpkins), and increases (apples and cantaloupes). The number of adult bee frames increased or remained stable in all crops except alfalfa and cotton. A total of 53 different pesticide residues were identified in samples collected across eight crops. Hazard quotients (HQ) were calculated for the combined residues for all crop-associated samples and separately for samples of dead and dying bees. A decrease in the number of departing foragers in cotton was one of the most substantial crop-associated impacts and presented the highest pesticide risk estimated by a summed pesticide residue HQ. PMID:26453703

Hypothermic stunning of green sea turtles in a western Gulf of Mexico foraging habitat

PubMed Central

Tissot, Philippe E.; Streich, Mary M.; Walker, Jennifer Shelby; Rubio, Cynthia; Amos, Anthony F.; George, Jeffrey A.; Pasawicz, Michelle R.

2017-01-01

Texas waters provide one of the most important developmental and foraging habitats for juvenile green turtles (Chelonia mydas) in the western Gulf of Mexico, but hypothermic stunning is a significant threat and was the largest cause of green turtle strandings in Texas from 1980 through 2015; of the 8,107 green turtles found stranded, 4,529 (55.9%) were victims of hypothermic stunning. Additionally, during this time, 203 hypothermic stunned green turtles were found incidentally captured due to power plant water intake entrapment. Overall, 63.9% of 4,529 hypothermic stunned turtles were found alive, and 92.0% of those survived rehabilitation and were released. Numbers of green turtles recorded as stranded and as affected by hypothermic stunning increased over time, and were most numerous from 2007 through 2015. Large hypothermic stunning events (with more than 450 turtles documented) occurred during the winters of 2009–2010, 2010–2011, 2013–2014, and 2014–2015. Hypothermic stunning was documented between November and March, but peaked at various times depending on passage of severe weather systems. Hypothermic stunning occurred state-wide, but was most prevalent in South Texas, particularly the Laguna Madre. In the Laguna Madre, hypothermic stunning was associated with an abrupt drop in water temperatures strong northerly winds, and a threshold mean water temperature of 8.0°C predicted large turtle hypothermic stunning events. Knowledge of environmental parameters contributing to hypothermic stunning and the temporal and spatial distribution of turtles affected in the past, can aid with formulation of proactive, targeted search and rescue efforts that can ultimately save the lives of many affected individuals, and aid with recovery efforts for this bi-national stock. Such rescue efforts are required under the U.S. Endangered Species Act and respond to humanitarian concerns of the public. PMID:28306747

GPS tracking devices reveal foraging strategies of black-legged kittiwakes

USGS Publications Warehouse

Kotzerka, Jana; Garthe, Stefan; Hatch, Scott A.

2010-01-01

The Black-legged Kittiwake Rissa tridactyla is the most abundant gull species in the world, but some populations have declined in recent years, apparently due to food shortage. Kittiwakes are surface feeders and thus can compensate for low food availability only by increasing their foraging range and/or devoting more time to foraging. The species is widely studied in many respects, but long-distance foraging and the limitations of conventional radio telemetry have kept its foraging behavior largely out of view. The development of Global Positioning System (GPS) loggers is advancing rapidly. With devices as small as 8 g now available, it is possible to use this technology for tracking relatively small species of oceanic birds like kittiwakes. Here we present the first results of GPS telemetry applied to Black-legged Kittiwakes in 2007 in the North Pacific. All but one individual foraged in the neritic zone north of the island. Three birds performed foraging trips only close to the colony (within 13 km), while six birds had foraging ranges averaging about 40 km. The maximum foraging range was 59 km, and the maximum distance traveled was 165 km. Maximum trip duration was 17 h (mean 8 h). An apparently bimodal distribution of foraging ranges affords new insight on the variable foraging behaviour of Black-legged Kittiwakes. Our successful deployment of GPS loggers on kittiwakes holds much promise for telemetry studies on many other bird species of similar size and provides an incentive for applying this new approach in future studies.

Nonstructural carbohydrate supplementation of yearling heifers and range beef cows.

PubMed

Bowman, J G P; Sowell, B F; Surber, L M M; Daniels, T K

2004-09-01

A digestion study with 28 yearling heifers (428 +/- 9.9 kg; Exp. 1) and a 2-yr winter grazing trial with 60 crossbred cows (552 +/- 6.9 kg; Exp. 2) were used to determine the effects of level of nonstructural carbohydrate (NSC) supplementation on intake and digestibility of low-quality forage. Treatments were as follows: 1) control, no supplement; 2) 0.32 kg of NSC (1.8 kg/d of soybean hulls and soybean meal; DM basis); 3) 0.64 kg of NSC (1.7 kg/d of wheat middlings; DM basis); and 4) 0.96 kg of NSC (1.7 kg/d of barley and soybean meal; DM basis). Supplements provided 0.34 kg of CP/d and 5.1 Mcal of ME/d. In Exp. 1, heifers were individually fed hay (5.5% CP, DM basis) and their respective supplements in Calan gates for 28 d. Data were analyzed as a completely randomized design. In Exp. 2, cows were individually fed supplement on alternate days, and grazed a single rangeland pasture stocked at 1.8 ha/ animal unit month. Two ruminally cannulated cows were used per treatment to obtain forage extrusa and to measure in situ DM disappearance (DMD) and carboxymethylcellulase (CMCase) activity of particle-associated ruminal microbes. Data were analyzed as a completely randomized design with the effects of treatment, year, and their interaction. In both experiments, Cr2O3 boluses were used to determine fecal output, individual animal was the experimental unit, and contrasts were used to test linear and quadratic effects of NSC level and control vs. supplemented treatments. In Exp. 1, hay and diet DM, NDF, and CP intakes and digestibilities were increased (P < 0.01) by NSC supplementation compared with the control. In Exp. 2, 72-h in situ DMD and CMCase were decreased linearly (P < 0.08) with increasing NSC supplementation. Intake of forage DM, NDF, and CP was decreased linearly (P < 0.01) with increasing NSC supplementation during both years. Supplementation with NSC decreased (P = 0.01) cow BW loss compared with the control in yr 1, whereas in yr 2, cow BW loss was linearly increased (P = 0.03) by increasing NSC supplementation. Supplements containing NSC improved forage digestion and intake when heifers consumed forage deficient in CP relative to energy (digestible OM:CP > 7), but decreased forage digestion and intake when cows grazed forage with adequate CP relative to energy (digestible OM:CP < 7). Forage and supplement digestible OM:CP seemed to be superior predictors of response to supplementation with NSC compared with forage CP levels alone.

Effects of stored feed cropping systems and farm size on the profitability of Maine organic dairy farm simulations.

PubMed

Hoshide, A K; Halloran, J M; Kersbergen, R J; Griffin, T S; DeFauw, S L; LaGasse, B J; Jain, S

2011-11-01

United States organic dairy production has increased to meet the growing demand for organic milk. Despite higher prices received for milk, organic dairy farmers have come under increasing financial stress due to increases in concentrated feed prices over the past few years, which can make up one-third of variable costs. Market demand for milk has also leveled in the last year, resulting in some downward pressure on prices paid to dairy farmers. Organic dairy farmers in the Northeast United States have experimented with growing different forage and grain crops to maximize on-farm production of protein and energy to improve profitability. Three representative organic feed systems were simulated using the integrated farm system model for farms with 30, 120, and 220 milk cows. Increasing intensity of equipment use was represented by organic dairy farms growing only perennial sod (low) to those with corn-based forage systems, which purchase supplemental grain (medium) or which produce and feed soybeans (high). The relative profitability of these 3 organic feed systems was strongly dependent on dairy farm size. From results, we suggest smaller organic dairy farms can be more profitable with perennial sod-based rather than corn-based forage systems due to lower fixed costs from using only equipment associated with perennial forage harvest and storage. The largest farm size was more profitable using a corn-based system due to greater economies of scale for growing soybeans, corn grain, winter cereals, and corn silages. At an intermediate farm size of 120 cows, corn-based forage systems were more profitable if perennial sod was not harvested at optimum quality, corn was grown on better soils, or if milk yield was 10% higher. Delayed harvest decreased the protein and energy content of perennial sod crops, requiring more purchased grain to balance the ration and resulting in lower profits. Corn-based systems were less affected by lower perennial forage quality, as corn silage is part of the forage base. Growing on better soils increased corn yields more than perennial forage yields. Large corn-based organic dairy farms that produced and fed soybeans minimized off-farm grain purchases and were the most profitable among large farms. Although perennial sod-based systems purchased more grain, these organic systems were more profitable under timely forage harvest, decreased soil quality, and relatively lower purchased energy prices and higher protein supplement prices. Copyright © 2011 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Longer guts and higher food quality increase energy intake in migratory swans.

PubMed

van Gils, Jan A; Beekman, Jan H; Coehoorn, Pieter; Corporaal, Els; Dekkers, Ten; Klaassen, Marcel; van Kraaij, Rik; de Leeuw, Rinze; de Vries, Peter P

2008-11-01

1. Within the broad field of optimal foraging, it is increasingly acknowledged that animals often face digestive constraints rather than constraints on rates of food collection. This therefore calls for a formalization of how animals could optimize food absorption rates. 2. Here we generate predictions from a simple graphical optimal digestion model for foragers that aim to maximize their (true) metabolizable food intake over total time (i.e. including nonforaging bouts) under a digestive constraint. 3. The model predicts that such foragers should maintain a constant food retention time, even if gut length or food quality changes. For phenotypically flexible foragers, which are able to change the size of their digestive machinery, this means that an increase in gut length should go hand in hand with an increase in gross intake rate. It also means that better quality food should be digested more efficiently. 4. These latter two predictions are tested in a large avian long-distance migrant, the Bewick's swan (Cygnus columbianus bewickii), feeding on grasslands in its Dutch wintering quarters. 5. Throughout winter, free-ranging Bewick's swans, growing a longer gut and experiencing improved food quality, increased their gross intake rate (i.e. bite rate) and showed a higher digestive efficiency. These responses were in accordance with the model and suggest maintenance of a constant food retention time. 6. These changes doubled the birds' absorption rate. Had only food quality changed (and not gut length), then absorption rate would have increased by only 67%; absorption rate would have increased by only 17% had only gut length changed (and not food quality). 7. The prediction that gross intake rate should go up with gut length parallels the mechanism included in some proximate models of foraging that feeding motivation scales inversely to gut fullness. We plea for a tighter integration between ultimate and proximate foraging models.

Forage yield increased by clearcutting and site preparation

Treesearch

John J. Stransky; Lowell K. Halls

1977-01-01

Total forage yield (TFY) on a pine-hardwood forest site in east Texas was sampled before and 1 growing season after clearcutting (1972 and 1973), also 1 and 3 growing seasons after planting site preparation by burning, choping, or KG blading (1974 and 1976). Total forage yield was only 359 ka/ha in the uncut forest, but 2217 kg/ha after clearcutting. On control plots (...

Effects of alfalfa hay and its physical form (chopped versus pelleted) on performance of Holstein calves.

PubMed

Jahani-Moghadam, M; Mahjoubi, E; Hossein Yazdi, M; Cardoso, F C; Drackley, J K

2015-06-01

Inclusion of forage and its physical form in starter may affect rumen development, average daily gain (ADG), and dry matter intake (DMI) of dairy calves. To evaluate the effects of forage and its physical form (chopped vs. pelleted) on growth of calves under a high milk feeding regimen, 32 Holstein calves (38.8±1.1kg) were assigned at birth to 1 of 3 treatments in a completely randomized block design. Dietary treatments (% of dry matter) were (1) 100% semi-texturized starter (CON); (2) 90% semi-texturized starter + 10% chopped alfalfa hay (mean particle size=5.4mm) as a total mixed ration (TMR; CH); and (3) 90% semi-texturized starter + 10% pelleted alfalfa (mean=5.8mm) hay as a TMR (PH). Data were subjected to mixed model analysis with contrasts used to evaluate effect of forage inclusion. Calves were weaned at 76 d of age and the experiment finished 2 wk after weaning. Individual milk and solid feed consumption were recorded daily. Solid feed consumption and ADG increased as age increased (effect of week), but neither forage inclusion nor physical form of forage affected these variables pre- or postweaning. Plasma urea N was affected by treatments such that the CON group had a lower concentration than forage-fed groups. Forage inclusion, but not physical form, resulted in increased total protein in plasma. Although days with elevated rectal temperature, fecal score, and general appearance were not affected by dietary treatments, calves fed alfalfa hay during the first month of life had fewer days with respiratory issues, regardless of physical form of hay. We concluded that provision of forage does have some beneficial effects in calves fed large amounts of milk replacer, but pelleted alfalfa hay did not result in any improvement in calf performance or health. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

By the Light of the Moon: North Pacific Dolphins Optimize Foraging with the Lunar Cycle

NASA Astrophysics Data System (ADS)

Simonis, Anne Elizabeth

The influence of the lunar cycle on dolphin foraging behavior was investigated in the productive, southern California Current Ecosystem and the oligotrophic Hawaiian Archipelago. Passive acoustic recordings from 2009 to 2015 were analyzed to document the presence of echolocation from four dolphin species that demonstrate distinct foraging preferences and diving abilities. Visual observations of dolphins, cloud coverage, commercial landings of market squid (Doryteuthis opalescens) and acoustic backscatter of fish were also considered in the Southern California Bight. The temporal variability of echolocation is described from daily to annual timescales, with emphasis on the lunar cycle as an established behavioral driver for potential dolphin prey. For dolphins that foraged at night, the presence of echolocation was reduced during nights of the full moon and during times of night that the moon was present in the night sky. In the Southern California Bight, echolocation activity was reduced for both shallow- diving common dolphins (Delphinus delphis) and deeper-diving Risso's dolphins (Grampus griseus) during times of increased illumination. Seasonal differences in acoustic behavior for both species suggest a geographic shift in dolphin populations, shoaling scattering layers or prey switching behavior during warm months, whereby dolphins target prey that do not vertically migrate. In the Hawaiian Archipelago, deep-diving short-finned pilot whales (Globicephala macrorhynchus) and shallow-diving false killer whales (Pseudorca crassidens) also showed reduced echolocation behavior during periods of increased lunar illumination. In contrast to nocturnal foraging in the northwestern Hawaiian Islands, false killer whales in the main Hawaiian Islands mainly foraged during the day and the lunar cycle showed little influence on their nocturnal acoustic behavior. Different temporal patterns in false killer whale acoustic behavior between the main and northwestern Hawaiian Islands can likely be attributed to the presence of distinct populations or social clusters with dissimilar foraging strategies. Consistent observations of reduced acoustic activity during times of increased lunar illumination show that the lunar cycle is an important predictor for nocturnal dolphin foraging behavior. The result of this research advances the scientific understanding of how dolphins optimize their foraging behavior in response to the changing distribution and abundance of their prey.

Fine scale bio-physical oceanographic characteristics predict the foraging occurrence of contrasting seabird species; Gannet (Morus bassanus) and storm petrel (Hydrobates pelagicus)

NASA Astrophysics Data System (ADS)

Scott, B. E.; Webb, A.; Palmer, M. R.; Embling, C. B.; Sharples, J.

2013-10-01

As we begin to manage our oceans in much more spatial detail we must understand a great deal more about oceanographic habitat preferences of marine mobile top predators. In this unique field study we test a hypothesis on the mechanisms defining mobile predator foraging habitat characteristics by comparing temporally and spatially detailed bio-physical oceanographic data from contrasting topographical locations. We contrast the foraging locations of two very different seabird species, gannets and storm petrels, by repeatedly sampling a bank and a nearby flat area over daily tidal cycles during spring and neap tides. The results suggest that storm petrels are linked to foraging in specific locations where internal waves are produced, which is mainly on banks. These locations can also include the presence of high biomass of chlorophyll. In contrast, the location where more gannets are foraging is significantly influenced by temporal variables with higher densities of foraging birds much more likely during the neap tide than times of spring tide. The foraging times of both species was influenced by differences between the vertical layers of the water column above and below the thermocline; via either vertical shear of horizontal currents or absolute differences in speed between layers. Higher densities of foraging gannets were significantly more likely to be found at ebb tides in both bank and flat regions however over the bank, the density of foraging gannets was higher when the differences in speed between the layers were at a maximum. Both gannets and storm petrels appear to be more likely to forage when wind direction is opposed to tidal direction. This detailed understanding links foraging behaviour to predictable spatial and temporal bio-physical vertical characteristics and thus can be immediately used to explain variance and increase certainty in past abundance and distributional surveys. These results also illuminate the types of variables that should be considered when assessing potential changes to the distribution and characteristics of habitats from increased anthropogenic disturbances such as large scale offshore wind, wave and tidal renewable deployments.

BILL E. KUNKLE INTERDISCIPLINARY BEEF SYMPOSIUM: A meta-analysis of research efforts aimed at reducing the impact of fescue toxicosis on cattle weight gain and feed intake.

PubMed

Gadberry, M S; Hawley, J; Beck, P A; Jennings, J A; Kegley, E B; Coffey, K P

2015-12-01

The objective of this paper is to present a systematic review and meta-analysis of research efforts aimed at recovering cattle production losses attributed to toxic endophyte-infected [ (Morgan-Jones & Gams.) Glenn, Bacon, & Hanlin comb. Nov.] tall fescue [ (Schreb.) Darbysh.]. The strategies presented include those 1) applied with forage systems, 2) based on pharmacological compounds and functional foods, and 3) based on supplemental dietary nutrients. Cattle BW gain and DM intake was the dependent response evaluated. Among the forage systems reviewed, studies with nontoxic, endophyte-infected tall fescue as a total replacement forage system demonstrated the greatest improvement in per-hectare (152 ± 27.5 kg/ha) and per-animal (0.29 ± 0.03 kg/d) BW gain. Studies with interseeded legumes have exhibited a small and highly variable BW gain effect size per hectare (52 ± 24.1 kg/ha) and per animal (0.11 ± 0.03 kg/d). The legume response was seasonal, with summer exhibiting the greatest benefit. Studies with chemicals that suppress plant growth demonstrated BW gain responses (0.17 ± 0.06 kg/d) equal to or greater than the response observed with legume studies. Cattle grazing toxic tall fescue responded well to anthelmentics, antimicrobial feed additives, and steroid implants, and the use of these technologies may additively help recover production losses. As a group, functional foods have not improved BW gain ( = 0.85). Studies with cattle supplemented with highly digestible fiber supplements observed a 0.15 kg greater BW gain compared with studies using starch- and sugar-based supplements ( < 0.05). Weight gain was positively impacted by the level of supplementation (0.06 kg/DM intake as percent BW). Supplement feed conversion was estimated at 6:1 for the highly digestible fiber supplements compared with 11:1 for starch-based supplements. Tall fescue forage DM intake was predicted to maximize at a supplemental feeding rate of 0.24% BW with a breakpoint at 0.5% BW, and total maximum DM intake (forage plus supplement) occurred at 2.7% BW when supplemental feeding approached 0.9% BW. Results from this meta-analysis should be useful for 1) establishing and comparing measured responses to theoretical improvements in BW gain when additive strategies are considered, 2) research planning, and 3) producer education.

Neural encoding of competitive effort in the anterior cingulate cortex.

PubMed

Hillman, Kristin L; Bilkey, David K

2012-09-01

In social environments, animals often compete to obtain limited resources. Strategically electing to work against another animal represents a cost-benefit decision. Is the resource worth an investment of competitive effort? The anterior cingulate cortex (ACC) has been implicated in cost-benefit decision-making, but its role in competitive effort has not been examined. We recorded ACC neurons in freely moving rats as they performed a competitive foraging choice task. When at least one of the two choice options demanded competitive effort, the majority of ACC neurons exhibited heightened and differential firing between the goal trajectories. Inter- and intrasession manipulations revealed that differential firing was not attributable to effort or reward in isolation; instead ACC encoding patterns appeared to indicate net utility assessments of available choice options. Our findings suggest that the ACC is important for encoding competitive effort, a cost-benefit domain that has received little neural-level investigation despite its predominance in nature.

Foraging across the life span: is there a reduction in exploration with aging?

PubMed Central

Mata, Rui; Wilke, Andreas; Czienskowski, Uwe

2013-01-01

Does foraging change across the life span, and in particular, with aging? We report data from two foraging tasks used to investigate age differences in search in external environments as well as internal search in memory. Overall, the evidence suggests that foraging behavior may undergo significant changes across the life span across internal and external search. In particular, we find evidence of a trend toward reduced exploration with increased age. We discuss these findings in light of theories that postulate a link between aging and reductions in novelty seeking and exploratory behavior. PMID:23616741

Patch dynamics of a foraging assemblage of bees.

PubMed

Wright, David Hamilton

1985-03-01

The composition and dynamics of foraging assemblages of bees were examined from the standpoint of species-level arrival and departure processes in patches of flowers. Experiments with bees visiting 4 different species of flowers in subalpine meadows in Colorado gave the following results: 1) In enriched patches the rates of departure of bees were reduced, resulting in increases in both the number of bees per species and the average number of species present. 2) The reduction in bee departure rates from enriched patches was due to mechanical factors-increased flower handling time, and to behavioral factors-an increase in the number of flowers visited per inflorescence and in the number of inflorescences visited per patch. Bees foraging in enriched patches could collect nectar 30-45% faster than those foraging in control patches. 3) The quantitative changes in foraging assemblages due to enrichment, in terms of means and variances of species population sizes, fraction of time a species was present in a patch, and in mean and variance of the number of species present, were in reasonable agreement with predictions drawn from queuing theory and studies in island biogeography. 4) Experiments performed with 2 species of flowers with different corolla tube lengths demonstrated that manipulation of resources of differing availability had unequal effects on particular subsets of the larger foraging community. The arrival-departure process of bees on flowers and the immigration-extinction process of species on islands are contrasted, and the value of the stochastic, species-level approach to community composition is briefly discussed.

Modelling foraging movements of diving predators: a theoretical study exploring the effect of heterogeneous landscapes on foraging efficiency

PubMed Central

Bartoń, Kamil A.; Scott, Beth E.; Travis, Justin M.J.

2014-01-01

Foraging in the marine environment presents particular challenges for air-breathing predators. Information about prey capture rates, the strategies that diving predators use to maximise prey encounter rates and foraging success are still largely unknown and difficult to observe. As well, with the growing awareness of potential climate change impacts and the increasing interest in the development of renewable sources it is unknown how the foraging activity of diving predators such as seabirds will respond to both the presence of underwater structures and the potential corresponding changes in prey distributions. Motivated by this issue we developed a theoretical model to gain general understanding of how the foraging efficiency of diving predators may vary according to landscape structure and foraging strategy. Our theoretical model highlights that animal movements, intervals between prey capture and foraging efficiency are likely to critically depend on the distribution of the prey resource and the size and distribution of introduced underwater structures. For multiple prey loaders, changes in prey distribution affected the searching time necessary to catch a set amount of prey which in turn affected the foraging efficiency. The spatial aggregation of prey around small devices (∼ 9 × 9 m) created a valuable habitat for a successful foraging activity resulting in shorter intervals between prey captures and higher foraging efficiency. The presence of large devices (∼ 24 × 24 m) however represented an obstacle for predator movement, thus increasing the intervals between prey captures. In contrast, for single prey loaders the introduction of spatial aggregation of the resources did not represent an advantage suggesting that their foraging efficiency is more strongly affected by other factors such as the timing to find the first prey item which was found to occur faster in the presence of large devices. The development of this theoretical model represents a useful starting point to understand the energetic reasons for a range of potential predator responses to spatial heterogeneity and environmental uncertainties in terms of search behaviour and predator–prey interactions. We highlight future directions that integrated empirical and modelling studies should take to improve our ability to predict how diving predators will be impacted by the deployment of manmade structures in the marine environment. PMID:25250211

Evaluating the use of plant hormones and biostimulators in forage pastures to enhance shoot dry biomass production by perennial ryegrass (Lolium perenne L.).

PubMed

Zaman, Mohammad; Kurepin, Leonid V; Catto, Warwick; Pharis, Richard P

2016-02-01

Fertilisation of established perennial ryegrass forage pastures with nitrogen (N)-based fertilisers is currently the most common practice used on farms to increase pasture forage biomass yield. However, over-fertilisation can lead to undesired environmental impacts, including nitrate leaching into waterways and increased gaseous emissions of ammonia and nitrous oxide to the atmosphere. Additionally, there is growing interest from pastoral farmers to adopt methods for increasing pasture dry matter yield which use 'natural', environmentally safe plant growth stimulators, together with N-based fertilisers. Such plant growth stimulators include plant hormones and plant growth promotive microorganisms such as bacteria and fungi ('biostimulators', which may produce plant growth-inducing hormones), as well as extracts of seaweed (marine algae). This review presents examples and discusses current uses of plant hormones and biostimulators, applied alone or together with N-based fertilisers, to enhance shoot dry matter yield of forage pasture species, with an emphasis on perennial ryegrass. © 2015 Society of Chemical Industry.

Potential for increased use of cereal grain forages on dairy operations

USDA-ARS?s Scientific Manuscript database

Farmers are increasingly using cereal grain cover crops, which allows them to take advantage of additional growing days in early spring and late fall. The use of cereal grain forages, such as rye, wheat, or triticale as cover crops helps to reduce soil and nutrient losses, and also allows for addit...

Yield and soil carbon sequestration in grazed pastures sown with two or five forage species

USDA-ARS?s Scientific Manuscript database

Increasing plant species richness is often associated with an increase in productivity and associated ecosystem services such as soil C sequestration. In this paper we report on a nine-year experiment to evaluate the relative forage production and C sequestration potential of grazed pastures sown to...

Generalized optimal risk allocation: foraging and antipredator behavior in a fluctuating environment.

PubMed

Higginson, Andrew D; Fawcett, Tim W; Trimmer, Pete C; McNamara, John M; Houston, Alasdair I

2012-11-01

Animals live in complex environments in which predation risk and food availability change over time. To deal with this variability and maximize their survival, animals should take into account how long current conditions may persist and the possible future conditions they may encounter. This should affect their foraging activity, and with it their vulnerability to predation across periods of good and bad conditions. Here we develop a comprehensive theory of optimal risk allocation that allows for environmental persistence and for fluctuations in food availability as well as predation risk. We show that it is the duration of good and bad periods, independent of each other, rather than the overall proportion of time exposed to each that is the most important factor affecting behavior. Risk allocation is most pronounced when conditions change frequently, and optimal foraging activity can either increase or decrease with increasing exposure to bad conditions. When food availability fluctuates rapidly, animals should forage more when food is abundant, whereas when food availability fluctuates slowly, they should forage more when food is scarce. We also show that survival can increase as variability in predation risk increases. Our work reveals that environmental persistence should profoundly influence behavior. Empirical studies of risk allocation should therefore carefully control the duration of both good and bad periods and consider manipulating food availability as well as predation risk.

Disruption of Foraging by a Dominant Invasive Species to Decrease Its Competitive Ability

PubMed Central

Westermann, Fabian Ludwig; Suckling, David Maxwell; Lester, Philip John

2014-01-01

Invasive species are a major threat to biodiversity when dominant within their newly established habitat. The globally distributed Argentine ant Linepithema humile has been reported to break the trade-off between interference and exploitative competition, achieve high population densities, and overpower nests of many endemic ant species. We have used the sensitivity of the Argentine ant to the synthetic trail pheromone (Z)-9-hexadecanal to investigate species interactions for the first time. We predicted that disrupting Argentine ant trail following behaviour would reduce their competitive ability and create an opportunity for three other resident species to increase their foraging success. Argentine ant success in the control was reduced with increasing pheromone concentration, as predicted, but interactions varied among competing resident species. These behavioural variations provide an explanation for observed differences in foraging success of the competing resident species and how much each of these individual competitors can increase their foraging if the competitive ability of the dominant invader is decreased. The mechanism for the observed increase in resource acquisition of resident species appears to be a decrease in aggressive behaviour displayed by the Argentine ant, which may create an opportunity for other resident species to forage more successfully. Our demonstration of species interactions with trail pheromone disruption is the first known case of reduced dominance under a pheromone treatment in ants. PMID:24594633

Interspecific signalling between mutualists: food-thieving drongos use a cooperative sentinel call to manipulate foraging partners

PubMed Central

Baigrie, Bruce D.; Thompson, Alex M.; Flower, Tom P.

2014-01-01

Interspecific communication is common in nature, particularly between mutualists. However, whether signals evolved for communication with other species, or are in fact conspecific signals eavesdropped upon by partners, is often unclear. Fork-tailed drongos (Dicrurus adsimilis) associate with mixed-species groups and often produce true alarms at predators, whereupon associating species flee to cover, but also false alarms to steal associating species' food (kleptoparasitism). Despite such deception, associating species respond to drongo non-alarm calls by increasing their foraging and decreasing vigilance. Yet, whether these calls represent interspecific sentinel signals remains unknown. We show that drongos produced a specific sentinel call when foraging with a common associate, the sociable weaver (Philetairus socius), but not when alone. Weavers increased their foraging and decreased vigilance when naturally associating with drongos, and in response to sentinel call playback. Further, drongos sentinel-called more often when weavers were moving, and weavers approached sentinel calls, suggesting a recruitment function. Finally, drongos sentinel-called when weavers fled following false alarms, thereby reducing disruption to weaver foraging time. Results therefore provide evidence of an ‘all clear’ signal that mitigates the cost of inaccurate communication. Our results suggest that drongos enhance exploitation of a foraging mutualist through coevolution of interspecific sentinel signals. PMID:25080343

A test of the critical assumption of the sensory bias model for the evolution of female mating preference using neural networks.

PubMed

Fuller, Rebecca C

2009-07-01

The sensory bias model for the evolution of mating preferences states that mating preferences evolve as correlated responses to selection on nonmating behaviors sharing a common sensory system. The critical assumption is that pleiotropy creates genetic correlations that affect the response to selection. I simulated selection on populations of neural networks to test this. First, I selected for various combinations of foraging and mating preferences. Sensory bias predicts that populations with preferences for like-colored objects (red food and red mates) should evolve more readily than preferences for differently colored objects (red food and blue mates). Here, I found no evidence for sensory bias. The responses to selection on foraging and mating preferences were independent of one another. Second, I selected on foraging preferences alone and asked whether there were correlated responses for increased mating preferences for like-colored mates. Here, I found modest evidence for sensory bias. Selection for a particular foraging preference resulted in increased mating preference for similarly colored mates. However, the correlated responses were small and inconsistent. Selection on foraging preferences alone may affect initial levels of mating preferences, but these correlations did not constrain the joint evolution of foraging and mating preferences in these simulations.

The amino acid composition of rumen-undegradable protein: a comparison between forages.

PubMed

Edmunds, B; Südekum, K-H; Bennett, R; Schröder, A; Spiekers, H; Schwarz, F J

2013-07-01

The objective of this study was to improve knowledge regarding the amino acid profile of the insoluble portion of ingested forage escaping rumen degradation. Six forage categories were analyzed. Categories varied in botanical composition and each contained 2 samples. Samples within categories were derived from the same parent material but differed in harvest, maturity, or conservation type. The rumen-undegradable protein of all forages was measured by incubation for 16h in the rumen of 3 nonlactating cows. All residues were corrected for microbial colonization. The AA profile of the residue was different to the original profile. Degradation trends of individual AA, in terms of increase or decrease relative to the original concentration, were similar between all forages. The AA profiles of forage residues, both within and between categories, were more similar to each other than to their respective original profile. This information may aid in improving the accuracy of estimating postruminal AA supply from forages while decreasing the number of samples required to be analyzed. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Walrus distributional and foraging response to changing ice and benthic conditions in the Chukchi Sea

USGS Publications Warehouse

Jay, Chadwick V.; Grebmeier, Jacqueline M.; Fischbach, Anthony S.

2012-01-01

Arctic species such as the Pacific walrus (Odobenus rosmarus divergens) are facing a rapidly changing environment. Walruses are benthic foragers and may shift their spatial patterns of foraging in response to changes in prey distribution. We used data from satellite radio-tags attached to walruses in 2009-2010 to map walrus foraging locations with concurrent sampling of benthic infauna to examine relationships between distributions of dominant walrus prey and spatial patterns of walrus foraging. Walrus foraging was concentrated offshore in the NE Chukchi Sea, and coastal areas of northwestern Alaska when sea ice was sparse. Walrus foraging areas in August-September were coincident with the biomass of two dominant bivalve taxa (Tellinidae and Nuculidae) and sipunculid worms. Walrusforaging costs associated with increased travel time to higher biomass food patches from land may be significantly higher than the costs from sea ice haul-outs and result in reduced energy storesin walruses. Identifying what resources are selected by walruses and how those resources are distributed in space and time will improve our ability to forecast how walruses might respond to a changing climate.

Field Margins, Foraging Distances and Their Impacts on Nesting Pollinator Success

PubMed Central

Rands, Sean A.; Whitney, Heather M.

2011-01-01

The areas of wild land around the edges of agricultural fields are a vital resource for many species. These include insect pollinators, to whom field margins provide both nest sites and important resources (especially when adjacent crops are not in flower). Nesting pollinators travel relatively short distances from the nest to forage: most species of bee are known to travel less than two kilometres away. In order to ensure that these pollinators have sufficient areas of wild land within reach of their nests, agricultural landscapes need to be designed to accommodate the limited travelling distances of nesting pollinators. We used a spatially-explicit modelling approach to consider whether increasing the width of wild strips of land within the agricultural landscape will enhance the amount of wild resources available to a nesting pollinator, and if it would impact differently on pollinators with differing foraging strategies. This was done both by creating field structures with a randomised geography, and by using landscape data based upon the British agricultural landscape. These models demonstrate that enhancing field margins should lead to an increase in the availability of forage to pollinators that nest within the landscape. With the exception of species that only forage within a very short range of their nest (less than 125 m), a given amount of field margin manipulation should enhance the proportion of land available to a pollinator for foraging regardless of the distance over which it normally travels to find food. A fixed amount of field edge manipulation should therefore be equally beneficial for both longer-distance nesting foragers such as honeybees, and short-distance foragers such as solitary bees. PMID:21991390

Fine-scale foraging movements by fish-eating killer whales (Orcinus orca) relate to the vertical distributions and escape responses of salmonid prey (Oncorhynchus spp.).

PubMed

Wright, Brianna M; Ford, John K B; Ellis, Graeme M; Deecke, Volker B; Shapiro, Ari Daniel; Battaile, Brian C; Trites, Andrew W

2017-01-01

We sought to quantitatively describe the fine-scale foraging behavior of northern resident killer whales ( Orcinus orca ), a population of fish-eating killer whales that feeds almost exclusively on Pacific salmon ( Oncorhynchus spp.). To reconstruct the underwater movements of these specialist predators, we deployed 34 biologging Dtags on 32 individuals and collected high-resolution, three-dimensional accelerometry and acoustic data. We used the resulting dive paths to compare killer whale foraging behavior to the distributions of different salmonid prey species. Understanding the foraging movements of these threatened predators is important from a conservation standpoint, since prey availability has been identified as a limiting factor in their population dynamics and recovery. Three-dimensional dive tracks indicated that foraging ( N  = 701) and non-foraging dives ( N  = 10,618) were kinematically distinct (Wilks' lambda: λ 16  = 0.321, P  < 0.001). While foraging, killer whales dove deeper, remained submerged longer, swam faster, increased their dive path tortuosity, and rolled their bodies to a greater extent than during other activities. Maximum foraging dive depths reflected the deeper vertical distribution of Chinook (compared to other salmonids) and the tendency of Pacific salmon to evade predators by diving steeply. Kinematic characteristics of prey pursuit by resident killer whales also revealed several other escape strategies employed by salmon attempting to avoid predation, including increased swimming speeds and evasive maneuvering. High-resolution dive tracks reconstructed using data collected by multi-sensor accelerometer tags found that movements by resident killer whales relate significantly to the vertical distributions and escape responses of their primary prey, Pacific salmon.

The dynamics of foraging trails in the tropical arboreal ant Cephalotes goniodontus.

PubMed

Gordon, Deborah M

2012-01-01

The foraging behavior of the arboreal turtle ant, Cephalotes goniodontus, was studied in the tropical dry forest of western Mexico. The ants collected mostly plant-derived food, including nectar and fluids collected from the edges of wounds on leaves, as well as caterpillar frass and lichen. Foraging trails are on small pieces of ephemeral vegetation, and persist in exactly the same place for 4-8 days, indicating that food sources may be used until they are depleted. The species is polydomous, occupying many nests which are abandoned cavities or ends of broken branches in dead wood. Foraging trails extend from trees with nests to trees with food sources. Observations of marked individuals show that each trail is travelled by a distinct group of foragers. This makes the entire foraging circuit more resilient if a path becomes impassable, since foraging in one trail can continue while a different group of ants forms a new trail. The colony's trails move around the forest from month to month; from one year to the next, only one colony out of five was found in the same location. There is continual searching in the vicinity of trails: ants recruited to bait within 3 bifurcations of a main foraging trail within 4 hours. When bait was offered on one trail, to which ants recruited, foraging activity increased on a different trail, with no bait, connected to the same nest. This suggests that the allocation of foragers to different trails is regulated by interactions at the nest.

Simulating secondary succession of elk forage values in a managed forest landscape, western Washington

USGS Publications Warehouse

Jenkins, Kurt J.; Starkey, Edward E.

1996-01-01

Modern timber management practices often influence forage production for elk (Cervus elaphus) on broad temporal and spatial scales in forested landscapes. We incorporated site-specific information on postharvesting forest succession and forage characteristics in a simulation model to evaluate past and future influences of forest management practices on forage values for elk in a commercially managed Douglas fir (Pseudotsuga menziesii, PSME)-western hemlock (Tsuga heterophylla, TSHE) forest in western Washington. We evaluated future effects of: (1) clear-cut logging 0, 20, and 40% of harvestable stands every five years; (2) thinning 20-year-old Douglas fir forests; and (3) reducing the harvesting cycle from 60 to 45 years. Reconstruction of historical patterns of vegetation succession indicated that forage values peaked in the 1960s and declined from the 1970s to the present, but recent values still were higher than may have existed in the unmanaged landscape in 1945. Increased forest harvesting rates had little short-term influence on forage trends because harvestable stands were scarce. Simulations of forest thinning also produced negligible benefits because thinning did not improve forage productivity appreciably at the stand level. Simulations of reduced harvesting cycles shortened the duration of declining forage values from approximately 30 to 15 years. We concluded that simulation models are useful tools for examining landscape responses of forage production to forest management strategies, but the options examined provided little potential for improving elk forages in the immediate future.

Learning to be different: Acquired skills, social learning, frequency dependence, and environmental variation can cause behaviourally mediated foraging specializations

USGS Publications Warehouse

Tinker, M.T.; Mangel, M.; Estes, J.A.

2009-01-01

Question: How does the ability to improve foraging skills by learning, and to transfer that learned knowledge, affect the development of intra-population foraging specializations? Features of the model: We use both a state-dependent life-history model implemented by stochastic dynamic programming (SDPM) and an individual-based model (IBM) to capture the dynamic nature of behavioural preferences in feeding. Variables in the SDPM include energy reserves, skill levels, energy and handling time per single prey item, metabolic rate, the rates at which skills are learned and forgotten, the effect of skills on handling time, and the relationship between energy reserves and fitness. Additional variables in the IBM include the probability of successful weaning, the logistic dynamics of the prey species with stochastic recruitment, the intensity of top-down control of prey by predators, the mean and variance in skill levels of new recruits, and the extent to which learned Information can be transmitted via matrilineal social learning. Key range of variables: We explore the effects of approaching the time horizon in the SDPM, changing the extent to which skills can improve with experience, increasing the rates of learning or forgetting of skills, changing whether the learning curve is constant, accelerating (T-shaped) or decelerating ('r'-shaped), changing both mean and maximum possible energy reserves, changing metabolic costs of foraging, and changing the rate of encounter with prey. Conclusions: The model results show that the following factors increase the degree of prey specialization observed in a predator population: (1) Experience handling a prey type can substantially improve foraging skills for that prey. (2) There is limited ability to retain complex learned skills for multiple prey types. (3) The learning curve for acquiring new foraging skills is accelerating, or J-shaped. (4) The metabolic costs of foraging are high relative to available energy reserves. (5) Offspring can learn foraging skills from their mothers (matrilineal social learning). (6) Food abundance is limited, such that average individual energy reserves are low Additionally, the following factors increase the likelihood of alternative specializations co-occurring in a predator population: (1) The predator exerts effective top-down control of prey abundance, resulting in frequency-dependent dynamics. (2) There is stochastic Variation in prey population dynamics, but this Variation is neither too extreme in magnitude nor too 'slow' with respect to the time required for an individual forager to learn new foraging skills. For a given predator population, we deduce that the degree of specialization will be highest for those prey types requiring complex capture or handling skills, while prey species that are both profitable and easy to capture and handle will be included in the diet of all individuals. Frequency-dependent benefits of selecting alternative prey types, combined with the ability of foragers to improve their foraging skills by learning, and transmit learned skills to offspring, can result in behaviourally mediated foraging specialization, and also lead to the co-existence of alternative specializations. The extent of such specialization is predicted to be a variable trait, increasing in locations or years when intra-specific competition is high relative to inter-specific competition. ?? 2009 M. Tim Tinker.

Use of non-natal estuaries by migratory striped bass (Morone saxatilis) in summer

USGS Publications Warehouse

Mather, M. E.; Finn, John T.; Ferry, K.H.; Deegan, Linda A.; Nelson, G.A.

2009-01-01

For most migratory fish, little is known about the location and size of foraging areas or how long individuals remain in foraging areas, even though these attributes may affect their growth, survival, and impact on local prey. We tested whether striped bass (Morone saxatilis Walbaum), found in Massachusetts in summer, were migratory, how long they stayed in non-natal estuaries, whether observed spatial patterns differed from random model predictions, whether fish returned to the same area across multiple years, and whether fishing effort could explain recapture patterns. Anchor tags were attached to striped bass that were caught and released in Massachusetts in 1999 and 2000, and recaptured between 1999 and 2007. In fall, tagged striped bass were caught south of where they were released in summer, confirming that fish were coastal migrants. In the first summer, 77% and 100% of the recaptured fish in the Great Marsh and along the Massachusetts coast, respectively, were caught in the same place where they were released. About two thirds of all fish recaptured near where they were released were caught 2-7 years after tagging. Our study shows that smaller (400-500 mm total length) striped bass migrate hundreds of kilometers along the Atlantic Ocean coast, cease their mobile lifestyle in summer when they use a relatively localized area for foraging (<20 km2), and return to these same foraging areas in subsequent years.

Reproductive constraints influence habitat accessibility, segregation, and preference of sympatric albatross species.

PubMed

Kappes, Michelle A; Shaffer, Scott A; Tremblay, Yann; Foley, David G; Palacios, Daniel M; Bograd, Steven J; Costa, Daniel P

2015-01-01

The spatiotemporal distribution of animals is dependent on a suite of factors, including the distribution of resources, interactions within and between species, physiological limitations, and requirements for reproduction, dispersal, or migration. During breeding, reproductive constraints play a major role in the distribution and behavior of central place foragers, such as pelagic seabirds. We examined the foraging behavior and marine habitat selection of Laysan (Phoebastria immutabilis) and black-footed (P. nigripes) albatrosses throughout their eight month breeding cycle at Tern Island, Northwest Hawaiian Islands to evaluate how variable constraints of breeding influenced habitat availability and foraging decisions. We used satellite tracking and light-based geolocation to determine foraging locations of individuals, and applied a biologically realistic null usage model to generate control locations and model habitat preference under a case-control design. Remotely sensed oceanographic data were used to characterize albatross habitats in the North Pacific. Individuals of both species ranged significantly farther and for longer durations during incubation and chick-rearing compared to the brooding period. Interspecific segregation of core foraging areas was observed during incubation and chick-rearing, but not during brooding. At-sea activity patterns were most similar between species during brooding; neither species altered foraging effort to compensate for presumed low prey availability and high energy demands during this stage. Habitat selection during long-ranging movements was most strongly associated with sea surface temperature for both species, with a preference for cooler ocean temperatures compared to overall availability. During brooding, lower explanatory power of habitat models was likely related to the narrow range of ocean temperatures available for selection. Laysan and black-footed albatrosses differ from other albatross species in that they breed in an oligotrophic marine environment. During incubation and chick-rearing, they travel to cooler, more productive waters, but are restricted to the low-productivity environment near the colony during brooding, when energy requirements are greatest. Compared to other albatross species, Laysan and black-footed albatrosses spend a greater proportion of time in flight when foraging, especially during the brooding period; this strategy may be adaptive for locating dispersed prey in an oligotrophic environment.

A fundamental study revisited: Quantitative evidence for territory quality in oystercatchers (Haematopus ostralegus) using GPS data loggers.

PubMed

Schwemmer, Philipp; Weiel, Stefan; Garthe, Stefan

2017-01-01

A fundamental study by Ens et al. (1992, Journal of Animal Ecology , 61, 703) developed the concept of two different nest-territory qualities in Eurasian oystercatchers ( Haematopus ostralegus , L.), resulting in different reproductive successes. "Resident" oystercatchers use breeding territories close to the high-tide line and occupy adjacent foraging territories on mudflats. "Leapfrog" oystercatchers breed further away from their foraging territories. In accordance with this concept, we hypothesized that both foraging trip duration and trip distance from the high-tide line to the foraging territory would be linearly related to distance between the nest site and the high tide line. We also expected tidal stage and time of day to affect this relationship. The former study used visual observations of marked oystercatchers, which could not be permanently tracked. This concept model can now be tested using miniaturized GPS devices able to record data at high temporal and spatial resolutions. Twenty-nine oystercatchers from two study sites were equipped with GPS devices during the incubation periods (however, not during chick rearing) over 3 years, providing data for 548 foraging trips. Trip distances from the high-tide line were related to distance between the nest and high-tide line. Tidal stage and time of day were included in a mixing model. Foraging trip distance, but not duration (which was likely more impacted by intake rate), increased with increasing distance between the nest and high-tide line. There was a site-specific effect of tidal stage on both trip parameters. Foraging trip duration, but not distance, was significantly longer during the hours of darkness. Our findings support and additionally quantify the previously developed concept. Furthermore, rather than separating breeding territory quality into two discrete classes, this classification should be extended by the linear relationship between nest-site and foraging location. Finally, oystercatcher's foraging territories overlapped strongly in areas of high food abundance.

8. The development and evolution of division of labor and foraging specialization in a social insect (Apis mellifera L.).

PubMed

Page, Robert E; Scheiner, Ricarda; Erber, Joachim; Amdam, Gro V

2006-01-01

How does complex social behavior evolve? What are the developmental building blocks of division of labor and specialization, the hallmarks of insect societies? Studies have revealed the developmental origins in the evolution of division of labor and specialization in foraging worker honeybees, the hallmarks of complex insect societies. Selective breeding for a single social trait, the amount of surplus pollen stored in the nest (pollen hoarding) revealed a phenotypic architecture of correlated traits at multiple levels of biological organization in facultatively sterile female worker honeybees. Verification of this phenotypic architecture in "wild-type" bees provided strong support for a "pollen foraging syndrome" that involves increased senso-motor responses, motor activity, associative learning, reproductive status, and rates of behavioral development, as well as foraging behavior. This set of traits guided further research into reproductive regulatory systems that were co-opted by natural selection during the evolution of social behavior. Division of labor, characterized by changes in the tasks performed by bees, as they age, is controlled by hormones linked to ovary development. Foraging specialization on nectar and pollen results also from different reproductive states of bees where nectar foragers engage in pre-reproductive behavior, foraging for nectar for self-maintenance, while pollen foragers perform foraging tasks associated with reproduction and maternal care, collecting protein.

Differential adult survival at close seabird colonies: The importance of spatial foraging segregation and bycatch risk during the breeding season.

PubMed

Genovart, Meritxell; Bécares, Juan; Igual, José-Manuel; Martínez-Abraín, Alejandro; Escandell, Raul; Sánchez, Antonio; Rodríguez, Beneharo; Arcos, José M; Oro, Daniel

2018-03-01

Marine megafauna, including seabirds, are critically affected by fisheries bycatch. However, bycatch risk may differ on temporal and spatial scales due to the uneven distribution and effort of fleets operating different fishing gear, and to focal species distribution and foraging behavior. Scopoli's shearwater Calonectris diomedea is a long-lived seabird that experiences high bycatch rates in longline fisheries and strong population-level impacts due to this type of anthropogenic mortality. Analyzing a long-term dataset on individual monitoring, we compared adult survival (by means of multi-event capture-recapture models) among three close predator-free Mediterranean colonies of the species. Unexpectedly for a long-lived organism, adult survival varied among colonies. We explored potential causes of this differential survival by (1) measuring egg volume as a proxy of food availability and parental condition; (2) building a specific longline bycatch risk map for the species; and (3) assessing the distribution patterns of breeding birds from the three study colonies via GPS tracking. Egg volume was very similar between colonies over time, suggesting that environmental variability related to habitat foraging suitability was not the main cause of differential survival. On the other hand, differences in foraging movements among individuals from the three colonies expose them to differential mortality risk, which likely influenced the observed differences in adult survival. The overlap of information obtained by the generation of specific bycatch risk maps, the quantification of population demographic parameters, and the foraging spatial analysis should inform managers about differential sensitivity to the anthropogenic impact at mesoscale level and guide decisions depending on the spatial configuration of local populations. The approach would apply and should be considered in any species where foraging distribution is colony-specific and mortality risk varies spatially. © 2017 John Wiley & Sons Ltd.

Multinational tagging efforts illustrate regional scale of distribution and threats for east pacific green turtles (Chelonia mydas agassizii).

PubMed

Hart, Catherine E; Blanco, Gabriela S; Coyne, Michael S; Delgado-Trejo, Carlos; Godley, Brendan J; Jones, T Todd; Resendiz, Antonio; Seminoff, Jeffrey A; Witt, Matthew J; Nichols, Wallace J

2015-01-01

To further describe movement patterns and distribution of East Pacific green turtles (Chelonia mydas agassizii) and to determine threat levels for this species within the Eastern Pacific. In order to do this we combined published data from existing flipper tagging and early satellite tracking studies with data from an additional 12 satellite tracked green turtles (1996-2006). Three of these were tracked from their foraging grounds in the Gulf of California along the east coast of the Baja California peninsula to their breeding grounds in Michoacán (1337-2928 km). In addition, three post-nesting females were satellite tracked from Colola beach, Michoacán to their foraging grounds in southern Mexico and Central America (941.3-3020 km). A further six turtles were tracked in the Gulf of California within their foraging grounds giving insights into the scale of ranging behaviour. Turtles undertaking long-distance migrations showed a tendency to follow the coastline. Turtles tracked within foraging grounds showed that foraging individuals typically ranged up to 691.6 km (maximum) from release site location. Additionally, we carried out threat analysis (using the cumulative global human impact in the Eastern Pacific) clustering pre-existing satellite tracking studies from Galapagos, Costa Rica, and data obtained from this study; this indicated that turtles foraging and nesting in Central American waters are subject to the highest anthropogenic impact. Considering that turtles from all three rookeries were found to migrate towards Central America, it is highly important to implement conservation plans in Central American coastal areas to ensure the survival of the remaining green turtles in the Eastern Pacific. Finally, by combining satellite tracking data from this and previous studies, and data of tag returns we created the best available distributional patterns for this particular sea turtle species, which emphasized that conservation measures in key areas may have positive consequences on a regional scale.

Multinational Tagging Efforts Illustrate Regional Scale of Distribution and Threats for East Pacific Green Turtles (Chelonia mydas agassizii)

PubMed Central

Hart, Catherine E.; Blanco, Gabriela S.; Coyne, Michael S.; Delgado-Trejo, Carlos; Godley, Brendan J.; Jones, T. Todd; Resendiz, Antonio; Seminoff, Jeffrey A.; Witt, Matthew J.; Nichols, Wallace J.

2015-01-01

To further describe movement patterns and distribution of East Pacific green turtles (Chelonia mydas agassizii) and to determine threat levels for this species within the Eastern Pacific. In order to do this we combined published data from existing flipper tagging and early satellite tracking studies with data from an additional 12 satellite tracked green turtles (1996-2006). Three of these were tracked from their foraging grounds in the Gulf of California along the east coast of the Baja California peninsula to their breeding grounds in Michoacán (1337-2928 km). In addition, three post-nesting females were satellite tracked from Colola beach, Michoacán to their foraging grounds in southern Mexico and Central America (941.3-3020 km). A further six turtles were tracked in the Gulf of California within their foraging grounds giving insights into the scale of ranging behaviour. Turtles undertaking long-distance migrations showed a tendency to follow the coastline. Turtles tracked within foraging grounds showed that foraging individuals typically ranged up to 691.6 km (maximum) from release site location. Additionally, we carried out threat analysis (using the cumulative global human impact in the Eastern Pacific) clustering pre-existing satellite tracking studies from Galapagos, Costa Rica, and data obtained from this study; this indicated that turtles foraging and nesting in Central American waters are subject to the highest anthropogenic impact. Considering that turtles from all three rookeries were found to migrate towards Central America, it is highly important to implement conservation plans in Central American coastal areas to ensure the survival of the remaining green turtles in the Eastern Pacific. Finally, by combining satellite tracking data from this and previous studies, and data of tag returns we created the best available distributional patterns for this particular sea turtle species, which emphasized that conservation measures in key areas may have positive consequences on a regional scale. PMID:25646803

Body mass and anaerobic tolerance influence vertical habitat selection in meso- and bathypelagic foraging toothed whales of the Bahamas

NASA Astrophysics Data System (ADS)

Joyce, T. W.; Durban, J. W.; Fearnbach, H. H.; Claridge, D. E.; Ballance, L. T.

2016-02-01

Diving and spatial distribution data from small (55g) satellite transmitter tags attached to five species of deep-diving toothed whales were used to examine the physiological and ecological tradeoffs influencing vertical foraging ranges in the Bahamas. These tradeoffs have important consequences in terms of the ecological impacts of different toothed whale predators on meso- and bathypelagic prey populations, and also on relative vulnerabilities to human impacts (e.g., noise, vessel-strike). Within this assemblage, larger toothed-whales were hypothesized to more efficiently access deeper prey by having the capacity to sustain longer dives, based on a divergence of metabolic rates from oxygen storage capacity as mass increases. However, the observed vertical foraging ranges of melon-headed whales (Peponocephala electra, n=13), short-finned pilot whales (Globicephala macrorhynchus, n=15), Blainville's beaked whales (Mesoplodon densirostris, n=12), Cuvier's beaked whales (Ziphius cavirostris, n=7), and sperm whales (Physeter macrocephalus, n=27), only weakly support hypothesized increases in dive duration and depth as power law functions body mass (R2=0.36 & 0.23). In particular, the relatively small beaked whales (M.d. 853kg; Z.c. 1557kg) performed extremely long and deep foraging dives (M.d. max. 67mins & 1888m; Z.c. max. 103mins & 1888m) relative to expectations of simple allometric scaling. Based on foraging dive durations and post-foraging dive recovery patterns, both beaked whales appear to exceed aerobic dive limits, which enabled access to bathypelagic niches but at the cost of significantly longer recovery periods between foraging dives and comparatively low foraging time efficiency (<29% of time in foraging strata). The inclusion of aerobic and anaerobic dive strategies in allometric models of dive duration and depth yielded considerably greater explanatory power (R2=0.96 & 0.90), providing an improved framework for interpreting the tradeoffs between body size, diving efficiency, and access to different prey layers. Vertical foraging ranges in turn had important implications in terms of responses to diurnal variation in light intensity, and the relative affinities of different species to deep-scattering and benthic boundary layers of prey.

Natural History of the Neotropical Arboreal Ant, Odontomachus hastatus: Nest Sites, Foraging Schedule, and Diet

PubMed Central

Camargo, Rafael X.; Oliveira, Paulo S.

2012-01-01

The ecology of most arboreal ants remains poorly documented because of the difficulty in accessing ant nests and foragers in the forest canopy. This study documents the nesting and foraging ecology of a large (∼13 mm total length) arboreal trap—jaw ant, Odontomachus hastatus (Fabricius) (Hymenoptera: Formicidae) in a sandy plain forest on Cardoso Island, off the coast of Southeast Brazil. The results showed that O. hastatus nested in root clusters of epiphytic bromeliads, most commonly Vriesea procera (70% of nest plants). Mature O. hastatus colonies include one to several queens and about 500 workers. Foraging by O. hastatus is primarily nocturnal year—round, with increased foraging activity during the wet/warm season. The foragers hunt singly in the trees, preying on a variety of canopy—dwelling arthropods, with flies, moths, ants, and spiders accounting for > 60% of the prey captured. Although predators often have impacts on prey populations, the ecological importance of O. hastatus remains to be studied. PMID:22957686

Short-term prey field lability constrains individual specialisation in resource selection and foraging site fidelity in a marine predator.

PubMed

Courbin, Nicolas; Besnard, Aurélien; Péron, Clara; Saraux, Claire; Fort, Jérôme; Perret, Samuel; Tornos, Jérémy; Grémillet, David

2018-04-16

Spatio-temporally stable prey distributions coupled with individual foraging site fidelity are predicted to favour individual resource specialisation. Conversely, predators coping with dynamic prey distributions should diversify their individual diet and/or shift foraging areas to increase net intake. We studied individual specialisation in Scopoli's shearwaters (Calonectris diomedea) from the highly dynamic Western Mediterranean, using daily prey distributions together with resource selection, site fidelity and trophic-level analyses. As hypothesised, we found dietary diversification, low foraging site fidelity and almost no individual specialisation in resource selection. Crucially, shearwaters switched daily foraging tactics, selecting areas with contrasting prey of varying trophic levels. Overall, information use and plastic resource selection of individuals with reduced short-term foraging site fidelity allow predators to overcome prey field lability. Our study is an essential step towards a better understanding of individual responses to enhanced environmental stochasticity driven by global changes, and of pathways favouring population persistence. © 2018 John Wiley & Sons Ltd/CNRS.

Dynamics of foraging trails in the Neotropical termite Velocitermes heteropterus (Isoptera: Termitidae).

PubMed

Haifig, Ives; Jost, Christian; Fourcassié, Vincent; Zana, Yossi; Costa-Leonardo, Ana Maria

2015-09-01

Foraging behavior in termites varies with the feeding habits of each species but often occurs through the formation of well-defined trails that connect the nest to food sources in species that build structured nests. We studied the formation of foraging trails and the change in caste ratio during foraging in the termite Velocitermes heteropterus. This species is widespread in Cerrado vegetation where it builds epigeal nests and forages in open-air at night. Our aim was to understand the processes involved in the formation of foraging trails, from the exploration of new unmarked areas to the recruitment of individuals to food and the stabilization of traffic on the trails, as well as the participation of the different castes during these processes. Foraging trails were videotaped in the laboratory and the videos were then analyzed both manually and automatically to assess the flow of individuals and the caste ratio on the trails as well as to examine the spatial organization of traffic over time. Foraging trails were composed of minor workers, major workers, and soldiers. The flow of individuals on the trails gradually increased from the beginning of the exploration of new areas up to the discovery of the food. The caste ratio remained constant throughout the foraging excursion: major workers, minor workers and soldiers forage in a ratio of 8:1:1, respectively. The speed of individuals was significantly different among castes, with major workers and soldiers being significantly faster than minor workers. Overall, our results show that foraging excursions in V. heteropterus may be divided in three different phases, characterized by individual speeds, differential flows and lane segregation. Copyright © 2015 Elsevier B.V. All rights reserved.

Shedding light on light: benefits of anthropogenic illumination to a nocturnally foraging shorebird.

PubMed

Dwyer, Ross G; Bearhop, Stuart; Campbell, Hamish A; Bryant, David M

2013-03-01

Intertidal habitats provide important feeding areas for migratory shorebirds. Anthropogenic developments along coasts can increase ambient light levels at night across adjacent inter-tidal zones. Here, we report the effects of elevated nocturnal light levels upon the foraging strategy of a migratory shorebird (common redshank Tringa totanus) overwintering on an industrialised estuary in Northern Europe. To monitor behaviour across the full intertidal area, individuals were located by day and night using VHF transmitters, and foraging behaviour was inferred from inbuilt posture sensors. Natural light was scored using moon-phase and cloud cover information and nocturnal artificial light levels were obtained using geo-referenced DMSP/OLS night-time satellite imagery at a 1-km resolution. Under high illumination levels, the commonest and apparently preferred foraging behaviour was sight-based. Conversely, birds feeding in areas with low levels of artificial light had an elevated foraging time and fed by touch, but switched to visual rather than tactile foraging behaviour on bright moonlit nights in the absence of cloud cover. Individuals occupying areas which were illuminated continuously by lighting from a large petrochemical complex invariably exhibited a visually based foraging behaviour independently of lunar phase and cloud cover. We show that ambient light levels affect the timing and distribution of foraging opportunities for redshank. We argue that light emitted from an industrial complex improved nocturnal visibility. This allowed sight-based foraging in place of tactile foraging, implying both a preference for sight-feeding and enhanced night-time foraging opportunities under these conditions. The study highlights the value of integrating remotely sensed data and telemetry techniques to assess the effect of anthropogenic change upon nocturnal behaviour and habitat use. © 2012 The Authors. Journal of Animal Ecology © 2012 British Ecological Society.

THE SEARCH DYNAMICS OF RECRUITED HONEY BEES, APIS MELLIFERA LIGUSTICA SPINOLA.

PubMed

Friesen, Larry Jon

1973-02-01

Some variables in the recruitment process of honey bees were studied as they affected the distribution and success of the searching population in the field. The dance language and odor dependence hypotheses were contrasted and their predictions compared with the following observations. 1. Recruits were attracted to the odors from the food which were carried by foragers and were dependent on these odors for success. 2. A monitoring of recruit densities in the field demonstrated an association of searchers with the forager flight path. 3. The degree of correspondence between the distribution of recruits and the direction of the flight path to the feeding site was correlated with wind direction, not search efficiency. 4. Feeding stations upwind of the hive provided the highest recruit success rates, shortest search times, and the least dependence on wind speed. Downwind stations provided the lowest recruit success rates, the longest search times, and the greatest dependence on wind speed. 5. A disproportionate increase in recruit success with an increase in the number of foragers visiting a feeding site was correlated with the density of the foragers in the field. 6. Increased bee densities at the feeding site, even with bees from different hives, increased recruit success and shortened search times. 7. The progression of and the extremely long intervals between the onset of recruit arrivals at areas along the forager flight path suggested communication among bees in the field and a dependence of recruit success on the density and growth of the searching population. These observations are compatible with an odor dependent search behavior and together fail to support the predictions of the dance language hypothesis. Dance attendants appeared to have been conditioned to the odors associated with returning foragers and, after leaving the hive, entered a searching population dependent on these odors for success. The dependence of recruit success on food odor at the feeding station, the density of foragers between this station and the hive, and the direction of the wind indicates that the integrity of the forager flight path was extremely important to this success. The distributions and extended search times of recruits indicated a search behavior based on positive anemotaxis during the perception of the proper combination of odors and negative anemotaxis after the loss of this stimulation.

Forage quality declines with rising temperatures, with implications for livestock production and methane emissions

NASA Astrophysics Data System (ADS)

Lee, Mark A.; Davis, Aaron P.; Chagunda, Mizeck G. G.; Manning, Pete

2017-03-01

Livestock numbers are increasing to supply the growing demand for meat-rich diets. The sustainability of this trend has been questioned, and future environmental changes, such as climate change, may cause some regions to become less suitable for livestock. Livestock and wild herbivores are strongly dependent on the nutritional chemistry of forage plants. Nutrition is positively linked to weight gains, milk production and reproductive success, and nutrition is also a key determinant of enteric methane production. In this meta-analysis, we assessed the effects of growing conditions on forage quality by compiling published measurements of grass nutritive value and combining these data with climatic, edaphic and management information. We found that forage nutritive value was reduced at higher temperatures and increased by nitrogen fertiliser addition, likely driven by a combination of changes to species identity and changes to physiology and phenology. These relationships were combined with multiple published empirical models to estimate forage- and temperature-driven changes to cattle enteric methane production. This suggested a previously undescribed positive climate change feedback, where elevated temperatures reduce grass nutritive value and correspondingly may increase methane production by 0.9 % with a 1 °C temperature rise and 4.5 % with a 5 °C rise (model average), thus creating an additional climate forcing effect. Future methane production increases are expected to be largest in parts of North America, central and eastern Europe and Asia, with the geographical extent of hotspots increasing under a high emissions scenario. These estimates require refinement and a greater knowledge of the abundance, size, feeding regime and location of cattle, and the representation of heat stress should be included in future modelling work. However, our results indicate that the cultivation of more nutritious forage plants and reduced livestock farming in warming regions may reduce this additional source of pastoral greenhouse gas emissions.

The oxidative debt of fasting: evidence for short- to medium-term costs of advanced fasting in adult king penguins.

PubMed

Schull, Quentin; Viblanc, Vincent A; Stier, Antoine; Saadaoui, Hédi; Lefol, Emilie; Criscuolo, François; Bize, Pierre; Robin, Jean-Patrice

2016-10-15

In response to prolonged periods of fasting, animals have evolved metabolic adaptations helping to mobilize body reserves and/or reduce metabolic rate to ensure a longer usage of reserves. However, those metabolic changes can be associated with higher exposure to oxidative stress, raising the question of how species that naturally fast during their life cycle avoid an accumulation of oxidative damage over time. King penguins repeatedly cope with fasting periods of up to several weeks. Here, we investigated how adult male penguins deal with oxidative stress after an experimentally induced moderate fasting period (PII) or an advanced fasting period (PIII). After fasting in captivity, birds were released to forage at sea. We measured plasmatic oxidative stress on the same individuals at the start and end of the fasting period and when they returned from foraging at sea. We found an increase in activity of the antioxidant enzyme superoxide dismutase along with fasting. However, PIII individuals showed higher oxidative damage at the end of the fast compared with PII individuals. When they returned from re-feeding at sea, all birds had recovered their initial body mass and exhibited low levels of oxidative damage. Notably, levels of oxidative damage after the foraging trip were correlated to the rate of mass gain at sea in PIII individuals but not in PII individuals. Altogether, our results suggest that fasting induces a transitory exposure to oxidative stress and that effort to recover in body mass after an advanced fasting period may be a neglected carryover cost of fasting. © 2016. Published by The Company of Biologists Ltd.

Effect of rumen-undegradable protein supplementation and fresh forage composition on nitrogen utilization of dairy ewes.

PubMed

Mikolayunas, C; Thomas, D L; Armentano, L E; Berger, Y M

2011-01-01

Previous trials with dairy ewes fed stored feeds indicate a positive effect of rumen-undegradable protein (RUP) supplementation on milk yield. However, dairy sheep production in the United States is primarily based on grazing mixed grass-legume pastures, which contain a high proportion of rumen-degradable protein. Two trials were conducted to evaluate the effects of high-RUP protein supplementation and fresh forage composition on milk yield and N utilization of lactating dairy ewes fed in confinement or on pasture. In a cut-and-carry trial, 16 multiparous dairy ewes in mid-lactation were randomly assigned to 8 pens of 2 ewes each. Pens were randomly assigned 1 of 2 protein supplementation treatments, receiving either 0.0 or 0.3 kg of a high-RUP protein supplement (Soy Pass, LignoTech USA Inc., Rothschild, WI) per day. Within supplementation treatment, pens were randomly assigned to 1 of 4 forage treatments, which were applied in a 4×4 Latin square design for 10-d periods. Forage treatments included the following percentages of orchardgrass:alfalfa dry matter: 25:75, 50:50, 75:25, and 100:0. No interactions were observed between supplement and forage treatments. Supplementation with a high-RUP source tended to increase milk yield by 9%. Milk yield, milk protein yield, milk urea N, and urinary urea N excretion increased linearly with increased percentage of alfalfa. Milk N efficiency was greatest on the 100% orchardgrass diet. In a grazing trial, 12 multiparous dairy ewes in mid lactation were randomly assigned to 3 groups of 4 ewes each. Within group, 2 ewes were randomly assigned to receive either 0.0 or 0.3 kg of a high-RUP protein supplement (SoyPlus, West Central Cooperative, Ralston, IA) per day. Grazing treatments were arranged in a 3×3 Latin square design and applied to groups for 10-d periods. Ewes grazed paddocks that contained the following percentages of surface area of pure stands of orchardgrass:alfalfa: 50:50, 75:25, and 100:0. No interactions were found between supplement and forage treatments. Milk yield, milk protein yield, and milk urea N increased linearly with increased percentage of alfalfa in the paddock. In conclusion, supplementing with high-RUP protein tended to increase milk yield and increasing the proportion of alfalfa in the diet increased dry matter intake, milk yield, and protein yield of lactating dairy ewes fed or grazing fresh forage. Copyright © 2011 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Macronutrient ratios in pollen shape bumble bee (Bombus impatiens) foraging strategies and floral preferences

PubMed Central

Vaudo, Anthony D.; Patch, Harland M.; Mortensen, David A.; Tooker, John F.; Grozinger, Christina M.

2016-01-01

To fuel their activities and rear their offspring, foraging bees must obtain a sufficient quality and quantity of nutritional resources from a diverse plant community. Pollen is the primary source of proteins and lipids for bees, and the concentrations of these nutrients in pollen can vary widely among host-plant species. Therefore we hypothesized that foraging decisions of bumble bees are driven by both the protein and lipid content of pollen. By successively reducing environmental and floral cues, we analyzed pollen-foraging preferences of Bombus impatiens in (i) host-plant species, (ii) pollen isolated from these host-plant species, and (iii) nutritionally modified single-source pollen diets encompassing a range of protein and lipid concentrations. In our semifield experiments, B. impatiens foragers exponentially increased their foraging rates of pollen from plant species with high protein:lipid (P:L) ratios; the most preferred plant species had the highest ratio (∼4.6:1). These preferences were confirmed in cage studies where, in pairwise comparisons in the absence of other floral cues, B. impatiens workers still preferred pollen with higher P:L ratios. Finally, when presented with nutritionally modified pollen, workers were most attracted to pollen with P:L ratios of 5:1 and 10:1, but increasing the protein or lipid concentration (while leaving ratios intact) reduced attraction. Thus, macronutritional ratios appear to be a primary factor driving bee pollen-foraging behavior and may explain observed patterns of host-plant visitation across the landscape. The nutritional quality of pollen resources should be taken into consideration when designing conservation habitats supporting bee populations. PMID:27357683

Puffins reveal contrasting relationships between forage fish and ocean climate in the North Pacific

USGS Publications Warehouse

Sydeman, William J.; Piatt, John F.; Thompson, Sarah Ann; Garcia-Reyes, Marisol; Hatch, Scott A.; Arimitsu, Mayumi L.; Slater, Leslie; Williams, Jeffrey C.; Rojek, Nora A.; Zador, Stephani G.; Renner, Heather M.

2017-01-01

Long-term studies of predator food habits (i.e., ‘predator-based sampling’) are useful for identifying patterns of spatial and temporal variability of forage nekton in marine ecosystems. We investigated temporal changes in forage fish availability and relationships to ocean climate by analyzing diet composition of three puffin species (horned puffin Fratercula corniculata, tufted puffin Fratercula cirrhata, and rhinoceros auklet Cerorhinca monocerata) from five sites in the North Pacific from 1978–2012. Dominant forage species included squids and hexagrammids in the western Aleutians, gadids and Pacific sand lance (Ammodytes personatus) in the eastern Aleutians and western Gulf of Alaska (GoA), and sand lance and capelin (Mallotus villosus) in the northern and eastern GoA. Interannual fluctuations in forage availability dominated variability in the western Aleutians, whereas lower-frequency shifts in forage fish availability dominated elsewhere. We produced regional multivariate indicators of sand lance, capelin, and age-0 gadid availability by combining data across species and sites using Principal Component Analysis, and related these indices to environmental factors including sea level pressure (SPL), winds, and sea surface temperature (SST). There was coherence in the availability of sand lance and capelin across the study area. Sand lance availability increased linearly with environmental conditions leading to warmer ocean temperatures, whereas capelin availability increased in a non-linear manner when environmental changes led to lower ocean temperatures. Long-term studies of puffin diet composition appear to be a promising tool for understanding the availability of these difficult-to-survey forage nekton in remote regions of the North Pacific.

Visual field shape and foraging ecology in diurnal raptors.

PubMed

Potier, Simon; Duriez, Olivier; Cunningham, Gregory B; Bonhomme, Vincent; O'Rourke, Colleen; Fernández-Juricic, Esteban; Bonadonna, Francesco

2018-05-18

Birds, particularly raptors, are believed to forage primarily using visual cues. However, raptor foraging tactics are highly diverse - from chasing mobile prey to scavenging - which may reflect adaptations of their visual systems. To investigate this, we studied the visual field configuration of 15 species of diurnal Accipitriformes that differ in such tactics, first focusing on the binocular field and blind area by using a single traits approach, and then exploring the shape of the binocular field with morphometric approaches. While the maximum binocular field width did not differ in species of different foraging tactics, the overall shape of their binocular fields did. In particular, raptors chasing terrestrial prey (ground predators) had a more protruding binocular field and a wider blind area above the head than did raptors chasing aerial or aquatic prey and obligate scavengers. Ground predators that forage on mammals from above have a wide but short bill - which increases ingestion rate - and large suborbital ridge to avoid sun glare. This may explain the protruding binocular field and the wide blind area above the head. By contrast, species from the two other groups have long but narrow bills used to pluck, flake or tear food and may need large visual coverage (and reduced suborbital ridges) to increase their foraging efficiency ( e.g. using large visual coverage to follow the escaping prey in three dimensions or detect conspecifics). We propose that binocular field shape is associated with bill and suborbital ridge shape and, ultimately, foraging strategies. © 2018. Published by The Company of Biologists Ltd.

The Dynamics of Foraging Trails in the Tropical Arboreal Ant Cephalotes goniodontus

PubMed Central

Gordon, Deborah M.

2012-01-01

The foraging behavior of the arboreal turtle ant, Cephalotes goniodontus, was studied in the tropical dry forest of western Mexico. The ants collected mostly plant-derived food, including nectar and fluids collected from the edges of wounds on leaves, as well as caterpillar frass and lichen. Foraging trails are on small pieces of ephemeral vegetation, and persist in exactly the same place for 4–8 days, indicating that food sources may be used until they are depleted. The species is polydomous, occupying many nests which are abandoned cavities or ends of broken branches in dead wood. Foraging trails extend from trees with nests to trees with food sources. Observations of marked individuals show that each trail is travelled by a distinct group of foragers. This makes the entire foraging circuit more resilient if a path becomes impassable, since foraging in one trail can continue while a different group of ants forms a new trail. The colony’s trails move around the forest from month to month; from one year to the next, only one colony out of five was found in the same location. There is continual searching in the vicinity of trails: ants recruited to bait within 3 bifurcations of a main foraging trail within 4 hours. When bait was offered on one trail, to which ants recruited, foraging activity increased on a different trail, with no bait, connected to the same nest. This suggests that the allocation of foragers to different trails is regulated by interactions at the nest. PMID:23209749

Estimating thermal regimes of bull trout and assessing the potential effects of climate warming on critical habitats

USGS Publications Warehouse

Jones, Leslie A.; Muhlfeld, Clint C.; Marshall, Lucy A.; McGlynn, Brian L.; Kershner, Jeffrey L.

2013-01-01

Understanding the vulnerability of aquatic species and habitats under climate change is critical for conservation and management of freshwater systems. Climate warming is predicted to increase water temperatures in freshwater ecosystems worldwide, yet few studies have developed spatially explicit modelling tools for understanding the potential impacts. We parameterized a nonspatial model, a spatial flow-routed model, and a spatial hierarchical model to predict August stream temperatures (22-m resolution) throughout the Flathead River Basin, USA and Canada. Model comparisons showed that the spatial models performed significantly better than the nonspatial model, explaining the spatial autocorrelation found between sites. The spatial hierarchical model explained 82% of the variation in summer mean (August) stream temperatures and was used to estimate thermal regimes for threatened bull trout (Salvelinus confluentus) habitats, one of the most thermally sensitive coldwater species in western North America. The model estimated summer thermal regimes of spawning and rearing habitats at <13 C° and foraging, migrating, and overwintering habitats at <14 C°. To illustrate the useful application of such a model, we simulated climate warming scenarios to quantify potential loss of critical habitats under forecasted climatic conditions. As air and water temperatures continue to increase, our model simulations show that lower portions of the Flathead River Basin drainage (foraging, migrating, and overwintering habitat) may become thermally unsuitable and headwater streams (spawning and rearing) may become isolated because of increasing thermal fragmentation during summer. Model results can be used to focus conservation and management efforts on populations of concern, by identifying critical habitats and assessing thermal changes at a local scale.

Impact of changing wind conditions on foraging and incubation success in male and female wandering albatrosses.

PubMed

Cornioley, Tina; Börger, Luca; Ozgul, Arpat; Weimerskirch, Henri

2016-09-01

Wind is an important climatic factor for flying animals as by affecting their locomotion, it can deeply impact their life-history characteristics. In the context of globally changing wind patterns, we investigated the mechanisms underlying recently reported increase in body mass of a population of wandering albatrosses (Diomedea exulans) with increasing wind speed over time. We built a foraging model detailing the effects of wind on movement statistics and ultimately on mass gained by the forager and mass lost by the incubating partner. We then simulated the body mass of incubating pairs under varying wind scenarios. We tracked the frequency at which critical mass leading to nest abandonment was reached to assess incubation success. We found that wandering albatrosses behave as time minimizers during incubation as mass gain was independent of any movement statistics but decreased with increasing mass at departure. Individuals forage until their energy requirements, which are determined by their body conditions, are fulfilled. This can come at the cost of their partner's condition as mass loss of the incubating partner depended on trip duration. This behaviour is consistent with strategies of long-lived species which favoured their own survival over their current reproductive attempt. In addition, wind speed increased ground speed which in turn reduced trip duration and males foraged further away than females at high ground speed. Contrasted against an independent data set, the simulation performed satisfactorily for males but less so for females under current wind conditions. The simulation predicted an increase in male body mass growth rate with increasing wind speed, whereas females' rate decreased. This trend may provide an explanation for the observed increase in mass of males but not of females. Conversely, the simulation predicted very few nest abandonments, which is in line with the high breeding success of this species and is contrary to the hypothesis that wind patterns impact incubation success by altering foraging movement. © 2016 The Authors. Journal of Animal Ecology © 2016 British Ecological Society.

Effects of feeding fatty acid calcium and the interaction of forage quality on production performance and biochemical indexes in early lactation cow.

PubMed

Hu, Z Y; Yin, Z Y; Lin, X Y; Yan, Z G; Wang, Z H

2015-10-01

Multiparous early lactation Holstein cows (n = 16) were used in a randomized complete block design to determine the effects of feeding fatty acid calcium and the interaction of forage quality on production performance and biochemical indexes in early lactation cow. Treatments were as follows: (i) feeding low-quality forage without supplying fatty acid calcium (Diet A), (ii) feeding low-quality forage with supplying 400 g fatty acid calcium (Diet B), (iii) feeding high-quality forage without supplying fatty acid calcium (Diet C) and (iv) feeding high-quality forage with supplying 400 g fatty acid calcium. This experiment consisted 30 days. The milk and blood samples were collected in the last day of the trail. Intakes were recorded in the last 2 days of the trail. Supplementation of fatty acid calcium decreased significantly dry matter intake (DMI) (p < 0.01). Addition fatty acid calcium decreased milk protein percentage (p < 0.01) and milk SNF percentage (p < 0.01), but increased MUN (p < 0.05). Supplemented fatty acid decreased concentration of blood BHBA (p < 0.05), but increased TG, NEFA, glucagon, GLP-1, CCK, leptin, ApoA-IV, serotonin and MSH concentration in blood, the CCK concentration and feed intake showed a significant negative correlation (p < 0.05). Journal of Animal Physiology and Animal Nutrition © 2015 Blackwell Verlag GmbH.

A nicotinic acetylcholine receptor agonist affects honey bee sucrose responsiveness and decreases waggle dancing.

PubMed

Eiri, Daren M; Nieh, James C

2012-06-15

A nicotinic acetylcholine receptor agonist, imidacloprid, impairs memory formation in honey bees and has general effects on foraging. However, little is known about how this agonist affects two specific aspects of foraging: sucrose responsiveness (SR) and waggle dancing (which recruits nestmates). Using lab and field experiments, we tested the effect of sublethal doses of imidacloprid on (1) bee SR with the proboscis extension response assay, and (2) free-flying foragers visiting and dancing for a sucrose feeder. Bees that ingested imidacloprid (0.21 or 2.16 ng bee(-1)) had higher sucrose response thresholds 1 h after treatment. Foragers that ingested imidacloprid also produced significantly fewer waggle dance circuits (10.5- and 4.5-fold fewer for 50% and 30% sucrose solutions, respectively) 24 h after treatment as compared with controls. However, there was no significant effect of imidacloprid on the sucrose concentrations that foragers collected at a feeder 24 h after treatment. Thus, imidacloprid temporarily increased the minimum sucrose concentration that foragers would accept (short time scale, 1 h after treatment) and reduced waggle dancing (longer time scale, 24 h after treatment). The effect of time suggests different neurological effects of imidacloprid resulting from the parent compound and its metabolites. Waggle dancing can significantly increase colony food intake, and thus a sublethal dose (0.21 ng bee(-1), 24 p.p.b.) of this commonly used pesticide may impair colony fitness.

Precision-feeding dairy heifers a high rumen-undegradable protein diet with different proportions of dietary fiber and forage-to-concentrate ratios.

PubMed

Koch, L E; Gomez, N A; Bowyer, A; Lascano, G J

2017-12-01

The addition of dietary fiber can alter nutrient and N utilization in precision-fed dairy heifers and may further benefit from higher inclusion levels of RUP. The objective of this experiment was to determine the effects of feeding a high-RUP diet when dietary fiber content was manipulated within differing forage-to-concentrate ratios (F:C) on nutrient utilization of precision-fed dairy heifers. Six rumen-cannulated Holstein heifers (555.4 ± 31.4 kg BW; 17.4 ± 0.1 mo) were randomly assigned to 2 levels of forage, high forage (HF; 60% forage) or low forage (LF; 45% forage), and to a fiber proportion sequence (low fiber: 100% oat hay and silage [OA], 0% wheat straw [WS]; medium fiber: 83.4% OA, 16.6% WS; and high fiber: 66.7% OA, 33.3% WS) administered according to a split-plot 3 × 3 Latin square design (21-d periods). Similar levels of N intake (1.70 g N/kg BW) and RUP (55% of CP) were provided. Data were analyzed as a split-plot, 3 × 3 Latin square design using a mixed model with fixed effects of period and treatment. A repeated measures model was used with data that had multiple measurements over time. No differences were observed for DM, OM, NDF, or ADF apparent digestibility coefficients (dC) between HF- and LF-fed heifers. Heifers receiving LF diets had greater starch dC compared to HF heifers. Increasing the fiber level through WS addition resulted in a linear reduction of OM dC. There was a linear interaction for DM dC with a concurrent linear interaction in NDF dC. Nitrogen intake, dC, and retention did not differ; however, urine and total N excretion increased linearly with added fiber. Predicted microbial CP flow (MP) linearly decreased with WS inclusion mainly in LF heifers, as indicated by a significant interaction between F:C and WS. Rumen pH linearly increased with WS addition, although no F:C effect was detected. Ruminal ammonia concentration had an opposite linear effect with respect to MP as WS increased. Diets with the higher proportion of fiber benefited the most from a high RUP supply, complementing the substantial reduction in predicted MP caused by the incremental dietary fiber concentration. These results suggest that RUP supplementation is a practical method for reestablishing optimal ruminal N balance in the event of increased dietary fiber through forage inclusion in precision-fed dairy heifer diets.

Increasing physically effective fiber content of dairy cow diets through forage proportion versus forage chop length: chewing and ruminal pH.

PubMed

Yang, W Z; Beauchemin, K A

2009-04-01

A study was conducted to evaluate whether the risk of acidosis in dairy cows can be lowered by increasing the physically effective fiber (peNDF) concentration of the diet, either through increased theoretical chop length of alfalfa silage or higher proportion of forage in the diet. The experiment was designed as a replicated 4 x 4 Latin square using 8 ruminally cannulated lactating dairy cows. Treatments were arranged in a 2 x 2 factorial design; 2 forage particle lengths (FPL) of alfalfa silage (short and long) were combined with low (35:65) and high (60:40) forage:concentrate (F:C) ratios [dry matter (DM) basis]. Dietary peNDF concentration (DM basis) was determined from the sum of the proportion of dietary DM retained either on the 2 sieves (8 and 19 mm) or on the 3 sieves (1.18, 8, and 19 mm) of the Penn State Particle Separator multiplied by the neutral detergent fiber concentration of the diet. The dietary peNDF concentrations were altered by changing the F:C or the FPL, and ranged from 10.7 to 17.5% using 2 sieves, or from 23.1 to 28.2% using 3 sieves. Intake of peNDF was increased by increasing FPL but not by increasing F:C ratio because of the reduction of DM intake at the higher F:C ratio. Chewing activity, including number of chews and chewing time, increased with increasing F:C ratio or FPL. Mean ruminal pH was elevated by 0.4 and 0.2 units with increasing F:C ratio and FPL, respectively. Lowering the F:C ratio decreased the duration that ruminal pH was below 5.8 (1.2 vs. 8 h/d). Increased F:C ratio or FPL reduced ruminal volatile fatty acids concentration from 137 to 122 or from 133 to 126 mM, respectively, whereas acetate:propionate ratio was increased from 2.55 to 3.46 with increasing F:C ratio. Dietary peNDF concentration measured using 2 sieves was correlated to chewing time (r = 0.57) and mean ruminal pH (r = 0.75), whereas dietary peNDF concentration measured using 3 sieves was correlated to mean ruminal pH (r = 0.83) and negatively correlated to the time that pH was below 5.8 (r = -0.78). This study shows that the risk of ruminal acidosis is high for cows fed a low F:C diet. Increasing the proportion of forage in the diet helps prevent ruminal acidosis through increased chewing time, a change in meal patterns, and decreased ruminal acid production. Increasing FPL elevates ruminal pH, but in low forage diets, increased FPL does not alleviate subacute acidosis because the fermentability of the diet is high and changes in chewing activity are marginal.

JPRS Report, Science & Technology Europe & Latin America.

DTIC Science & Technology

1988-02-22

and a diagnostic test for paracetamol poisoning. Encouraged by this first experi- ence, the company focused its efforts on biosensors capable of...information about the microscopic mechanism responsible for the observed Tc- degradation . The step by step modification of the properties of a...of microorganisms. 5. Bibliographical References Akin, D.E. Forage cell wall degradation and p-coumaric, ferulic, and sinaptic acids. Agron. J

75 FR 57496 - Notice of Proposed Supplementary Rule To Require the Use of Certified Noxious-Weed-Free Forage...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-21

... mulch for project work. This action is a cooperative effort between the BLM, the U.S. Forest Service... a week. SUPPLEMENTARY INFORMATION: I. Public Comment Procedures You may mail comments to Roger... work. Once this rule becomes effective, there will be a 60-day grace period for enforcement of this...

Search path of a fossorial herbivore, Geomys bursarius, foraging in structurally complex plant communities

USGS Publications Warehouse

Andersen, Douglas C.

1990-01-01

The influence of habitat patchiness and unpalatable plants on the search path of the plains pocket gopher (Geomys bursarius) was examined in outdoor enclosures. Separate experiments were used to evaluate how individual animals explored (by tunnel excavation) enclosures free of plants except for one or more dense patches of a palatable plant (Daucus carota), a dense patch of an unpalatable species (Pastinaca sativa) containing a few palatable plants (D. carota), or a relatively sparse mixture of palatable (D. carota) and unpalatable (Raphanus sativus) species. Only two of eight individuals tested showed the predicted pattern of concentrating search effort in patches of palatable plants. The maintenance of relatively high levels of effort in less profitable sites may reflect the security afforded food resources by the solitary social system and fossorial lifestyle of G. bursarius. Unpalatable plants repelled animals under some conditions, but search paths in the sparsely planted mixed-species treatment suggest animals can use visual or other cues to orient excavations. Evidence supporting area-restricted search was weak. More information about the use of visual cues by G. bursarius and the influence of experience on individual search mode is needed for refining current models of foraging behavior in this species.

Does food availability affect energy expenditure rates of nesting seabirds? A supplemental-feeding experiment with Black-Legged Kittiwakes (Rissa tridactyla)

USGS Publications Warehouse

Jodice, Patrick G.R.; Roby, Daniel D.; Hatch, Scott A.; Gill, Verena A.; Lanctot, Richard B.; Visser, G. Henk

2002-01-01

We used a supplemental-feeding experiment, the doubly labeled water technique, and a model-selection approach based upon the Akaike Information Criterion to examine effects of food availability on energy expenditure rates of Black-legged Kittiwakes (Rissa tridactyla) raising young. Energy expenditure rates of supplementally fed females (n = 14) and males (n = 16) were 34 and 20% lower than those of control females (n = 14) and males (n = 18), respectively. Energy expenditure rates of females were more responsive to fluctuations in food availability than those of males. Fed males likely expended more energy while off the nest than fed females, possibly because of nest defense. Energy expenditure rates of fed kittiwakes were similar to values reported for kittiwakes that were either not raising young or not foraging. Parent kittiwakes, therefore, adjusted parental effort in response to variation in breeding conditions due to changes in food availability. Adjustments in reproductive effort in response to variable foraging conditions may have significant effects on the survival and productivity of individuals, and thus provide substantial fitness benefits for long-lived seabirds such as Black-legged Kittiwakes.

Hydrocarbons Emitted by Waggle-Dancing Honey Bees Increase Forager Recruitment by Stimulating Dancing

PubMed Central

Gilley, David C.

2014-01-01

Hydrocarbons emitted by waggle-dancing honey bees are known to reactivate experienced foragers to visit known food sources. This study investigates whether these hydrocarbons also increase waggle-dance recruitment by observing recruitment and dancing behavior when the dance compounds are introduced into the hive. If the hydrocarbons emitted by waggle-dancing bees affect the recruitment of foragers to a food source, then the number of recruits arriving at a food source should be greater after introduction of dance compounds versus a pure-solvent control. This prediction was supported by the results of experiments in which recruits were captured at a feeder following introduction of dance-compounds into a hive. This study also tested two nonexclusive behavioral mechanism(s) by which the compounds might stimulate recruitment; 1) increased recruitment could occur by means of increasing the recruitment effectiveness of each dance and/or 2) increased recruitment could occur by increasing the intensity of waggle-dancing. These hypotheses were tested by examining video records of the dancing and recruitment behavior of individually marked bees following dance-compound introduction. Comparisons of numbers of dance followers and numbers of recruits per dance and waggle run showed no significant differences between dance-compound and solvent-control introduction, thus providing no support for the first hypothesis. Comparison of the number of waggle-dance bouts and the number of waggle runs revealed significantly more dancing during morning dance-compound introduction than morning solvent-control introduction, supporting the second hypothesis. These results suggest that the waggle-dance hydrocarbons play an important role in honey bee foraging recruitment by stimulating foragers to perform waggle dances following periods of inactivity. PMID:25140740

Hydrocarbons emitted by waggle-dancing honey bees increase forager recruitment by stimulating dancing.

PubMed

Gilley, David C

2014-01-01

Hydrocarbons emitted by waggle-dancing honey bees are known to reactivate experienced foragers to visit known food sources. This study investigates whether these hydrocarbons also increase waggle-dance recruitment by observing recruitment and dancing behavior when the dance compounds are introduced into the hive. If the hydrocarbons emitted by waggle-dancing bees affect the recruitment of foragers to a food source, then the number of recruits arriving at a food source should be greater after introduction of dance compounds versus a pure-solvent control. This prediction was supported by the results of experiments in which recruits were captured at a feeder following introduction of dance-compounds into a hive. This study also tested two nonexclusive behavioral mechanism(s) by which the compounds might stimulate recruitment; 1) increased recruitment could occur by means of increasing the recruitment effectiveness of each dance and/or 2) increased recruitment could occur by increasing the intensity of waggle-dancing. These hypotheses were tested by examining video records of the dancing and recruitment behavior of individually marked bees following dance-compound introduction. Comparisons of numbers of dance followers and numbers of recruits per dance and waggle run showed no significant differences between dance-compound and solvent-control introduction, thus providing no support for the first hypothesis. Comparison of the number of waggle-dance bouts and the number of waggle runs revealed significantly more dancing during morning dance-compound introduction than morning solvent-control introduction, supporting the second hypothesis. These results suggest that the waggle-dance hydrocarbons play an important role in honey bee foraging recruitment by stimulating foragers to perform waggle dances following periods of inactivity.

Increasing metabolic rate despite declining body weight in an adult parasitoid wasp.

PubMed

Casas, Jérôme; Body, Mélanie; Gutzwiller, Florence; Giron, David; Lazzari, Claudio R; Pincebourde, Sylvain; Richard, Romain; Llandres, Ana L

2015-08-01

Metabolic rate is a positive function of body weight, a rule valid for most organisms and the basis of several theories of metabolic ecology. For adult insects, however, the diversity of relationships between body mass and respiration remains unexplained. The aim of this study is to relate the respiratory metabolism of a parasitoid with body weight and foraging activity. We compared the metabolic rate of groups of starving and host-fed females of the parasitoid Eupelmus vuilleti recorded with respirometry for 7days, corresponding to the mean lifetime of starving females and over half of the lifetime of foraging females. The dynamics of carbohydrate, lipid and protein in the body of foraging females were quantified with biochemical techniques. Body mass and all body nutrients declined sharply from the first day onwards. By contrast, the CO2 produced and the O2 consumed increased steadily. Starving females showed the opposite trend, identifying foraging as the reason for the respiration increase of feeding females. Two complementary physiological processes explain the unexpected relationship between increasing metabolic rate and declining body weight. First, host hemolymph is a highly unbalanced food, and the excess nutrients (protein and carbohydrate) need to be voided, partially through excretion and partially through respiration. Second, a foraging young female produces eggs at an increasing rate during the first half of its lifetime, a process that also increases respiration. We posit that the time-varying metabolic rate contributions of the feeding and reproductive processes supplements the contribution of the structural mass and lead to the observed trend. We extend our explanations to other insect groups and discuss the potential for unification using Dynamic Energy Budget theory. Copyright © 2015 Elsevier Ltd. All rights reserved.

Optimal foraging in seasonal environments: implications for residency of Australian flying foxes in food-subsidized urban landscapes.

PubMed

Páez, David J; Restif, Olivier; Eby, Peggy; Plowright, Raina K

2018-05-05

Bats provide important ecosystem services such as pollination of native forests; they are also a source of zoonotic pathogens for humans and domestic animals. Human-induced changes to native habitats may have created more opportunities for bats to reside in urban settings, thus decreasing pollination services to native forests and increasing opportunities for zoonotic transmission. In Australia, fruit bats ( Pteropus spp. flying foxes) are increasingly inhabiting urban areas where they feed on anthropogenic food sources with nutritional characteristics and phenology that differ from native habitats. We use optimal foraging theory to investigate the relationship between bat residence time in a patch, the time it takes to search for a new patch (simulating loss of native habitat) and seasonal resource production. We show that it can be beneficial to reside in a patch, even when food productivity is low, as long as foraging intensity is low and the expected searching time is high. A small increase in the expected patch searching time greatly increases the residence time, suggesting nonlinear associations between patch residence and loss of seasonal native resources. We also found that sudden increases in resource consumption due to an influx of new bats has complex effects on patch departure times that again depend on expected searching times and seasonality. Our results suggest that the increased use of urban landscapes by bats may be a response to new spatial and temporal configurations of foraging opportunities. Given that bats are reservoir hosts of zoonotic diseases, our results provide a framework to study the effects of foraging ecology on disease dynamics.One contribution of 14 to a theme isssue 'Anthropogenic resource subsidies and host-parasite dynamics in wildlife'. © 2018 The Author(s).

Sub-lethal effects of dietary neonicotinoid insecticide exposure on honey bee queen fecundity and colony development

NASA Astrophysics Data System (ADS)

Wu-Smart, Judy; Spivak, Marla

2016-08-01

Many factors can negatively affect honey bee (Apis mellifera L.) health including the pervasive use of systemic neonicotinoid insecticides. Through direct consumption of contaminated nectar and pollen from treated plants, neonicotinoids can affect foraging, learning, and memory in worker bees. Less well studied are the potential effects of neonicotinoids on queen bees, which may be exposed indirectly through trophallaxis, or food-sharing. To assess effects on queen productivity, small colonies of different sizes (1500, 3000, and 7000 bees) were fed imidacloprid (0, 10, 20, 50, and 100 ppb) in syrup for three weeks. We found adverse effects of imidacloprid on queens (egg-laying and locomotor activity), worker bees (foraging and hygienic activities), and colony development (brood production and pollen stores) in all treated colonies. Some effects were less evident as colony size increased, suggesting that larger colony populations may act as a buffer to pesticide exposure. This study is the first to show adverse effects of imidacloprid on queen bee fecundity and behavior and improves our understanding of how neonicotinoids may impair short-term colony functioning. These data indicate that risk-mitigation efforts should focus on reducing neonicotinoid exposure in the early spring when colonies are smallest and queens are most vulnerable to exposure.

Sub-lethal effects of dietary neonicotinoid insecticide exposure on honey bee queen fecundity and colony development

PubMed Central

Wu-Smart, Judy; Spivak, Marla

2016-01-01

Many factors can negatively affect honey bee (Apis mellifera L.) health including the pervasive use of systemic neonicotinoid insecticides. Through direct consumption of contaminated nectar and pollen from treated plants, neonicotinoids can affect foraging, learning, and memory in worker bees. Less well studied are the potential effects of neonicotinoids on queen bees, which may be exposed indirectly through trophallaxis, or food-sharing. To assess effects on queen productivity, small colonies of different sizes (1500, 3000, and 7000 bees) were fed imidacloprid (0, 10, 20, 50, and 100 ppb) in syrup for three weeks. We found adverse effects of imidacloprid on queens (egg-laying and locomotor activity), worker bees (foraging and hygienic activities), and colony development (brood production and pollen stores) in all treated colonies. Some effects were less evident as colony size increased, suggesting that larger colony populations may act as a buffer to pesticide exposure. This study is the first to show adverse effects of imidacloprid on queen bee fecundity and behavior and improves our understanding of how neonicotinoids may impair short-term colony functioning. These data indicate that risk-mitigation efforts should focus on reducing neonicotinoid exposure in the early spring when colonies are smallest and queens are most vulnerable to exposure. PMID:27562025

Management, morphological, and environmental factors influencing Douglas-fir bark furrows in the Oregon Coast Range

USGS Publications Warehouse

Sheridan, Christopher D.; Puettmann, Klaus J.; Huso, Manuela M.P.; Hagar, Joan C.; Falk, Kristen R.

2013-01-01

Many land managers in the Pacific Northwest have the goal of increasing late-successional forest structures. Despite the documented importance of Douglas-fir tree bark structure in forested ecosystems, little is known about factors influencing bark development and how foresters can manage development. This study investigated the relative importance of tree size, growth, environmental factors, and thinning on Douglas-fir bark furrow characteristics in the Oregon Coast Range. Bark furrow depth, area, and bark roughness were measured for Douglas-fir trees in young heavily thinned and unthinned sites and compared to older reference sites. We tested models for relationships between bark furrow response and thinning, tree diameter, diameter growth, and environmental factors. Separately, we compared bark responses measured on trees used by bark-foraging birds with trees with no observed usage. Tree diameter and diameter growth were the most important variables in predicting bark characteristics in young trees. Measured environmental variables were not strongly related to bark characteristics. Bark furrow characteristics in old trees were influenced by tree diameter and surrounding tree densities. Young trees used by bark foragers did not have different bark characteristics than unused trees. Efforts to enhance Douglas-fir bark characteristics should emphasize retention of larger diameter trees' growth enhancement.

Floral Resource Competition Between Honey Bees and Wild Bees: Is There Clear Evidence and Can We Guide Management and Conservation?

PubMed

Wojcik, Victoria A; Morandin, Lora A; Davies Adams, Laurie; Rourke, Kelly E

2018-06-05

Supporting managed honey bees by pasturing in natural landscapes has come under review due to concerns that honey bees could negatively impact the survival of wild bees through competition for floral resources. Critique and assessment of the existing body of published literature against our criteria focussing on studies that can support best management resulted in 19 experimental papers. Indirect measures of competition examining foraging patterns and behavior yielded equivocal results. Direct measures of reproduction and growth were investigated in only seven studies, with six indicating negative impacts to wild bees from the presence of managed honey bees. Three of these studies examined fitness impacts to BombusLatreille and all three indicated reduced growth or reduced reproductive output. Because there is a severe lack of literature, yet potential that honey bee presence could negatively impact wild bees, exemplified with bumble bee studies, we advocate for further research into the fitness impacts of competition between managed and wild pollinators. Conservative approaches should be taken with respect to pasturing honey bees on natural lands with sensitive bumble bee populations. Correspondingly, forage opportunities for honey bees in managed, agricultural landscapes, should be increased in an effort to reduce potential pressure and infringement on wild bee populations in natural areas.

Epidemiological models to control the spread of information in marine mammals.

PubMed

Schakner, Zachary A; Buhnerkempe, Michael G; Tennis, Mathew J; Stansell, Robert J; van der Leeuw, Bjorn K; Lloyd-Smith, James O; Blumstein, Daniel T

2016-12-14

Socially transmitted wildlife behaviours that create human-wildlife conflict are an emerging problem for conservation efforts, but also provide a unique opportunity to apply principles of infectious disease control to wildlife management. As an example, California sea lions (Zalophus californianus) have learned to exploit concentrations of migratory adult salmonids below the fish ladders at Bonneville Dam, impeding endangered salmonid recovery. Proliferation of this foraging behaviour in the sea lion population has resulted in a controversial culling programme of individual sea lions at the dam, but the impact of such culling remains unclear. To evaluate the effectiveness of current and alternative culling strategies, we used network-based diffusion analysis on a long-term dataset to demonstrate that social transmission is implicated in the increase in dam-foraging behaviour and then studied different culling strategies within an epidemiological model of the behavioural transmission data. We show that current levels of lethal control have substantially reduced the rate of social transmission, but failed to effectively reduce overall sea lion recruitment. Earlier implementation of culling could have substantially reduced the extent of behavioural transmission and, ultimately, resulted in fewer animals being culled. Epidemiological analyses offer a promising tool to understand and control socially transmissible behaviours. © 2016 The Author(s).

Sub-lethal effects of dietary neonicotinoid insecticide exposure on honey bee queen fecundity and colony development.

PubMed

Wu-Smart, Judy; Spivak, Marla

2016-08-26

Many factors can negatively affect honey bee (Apis mellifera L.) health including the pervasive use of systemic neonicotinoid insecticides. Through direct consumption of contaminated nectar and pollen from treated plants, neonicotinoids can affect foraging, learning, and memory in worker bees. Less well studied are the potential effects of neonicotinoids on queen bees, which may be exposed indirectly through trophallaxis, or food-sharing. To assess effects on queen productivity, small colonies of different sizes (1500, 3000, and 7000 bees) were fed imidacloprid (0, 10, 20, 50, and 100 ppb) in syrup for three weeks. We found adverse effects of imidacloprid on queens (egg-laying and locomotor activity), worker bees (foraging and hygienic activities), and colony development (brood production and pollen stores) in all treated colonies. Some effects were less evident as colony size increased, suggesting that larger colony populations may act as a buffer to pesticide exposure. This study is the first to show adverse effects of imidacloprid on queen bee fecundity and behavior and improves our understanding of how neonicotinoids may impair short-term colony functioning. These data indicate that risk-mitigation efforts should focus on reducing neonicotinoid exposure in the early spring when colonies are smallest and queens are most vulnerable to exposure.

Altering physically effective fiber intake through forage proportion and particle length: chewing and ruminal pH.

PubMed

Yang, W Z; Beauchemin, K A

2007-06-01

Alfalfa silages varying in theoretical chop length and diets high and low in forage proportion were used to evaluate whether increasing the physically effective (pe) neutral detergent fiber (NDF) content of dairy cow diets reduces the risk of acidosis. The experiment was designed as a replicated 4 x 4 Latin square using 8 ruminally cannulated lactating dairy cows. Treatments were arranged in a 2 x 2 factorial design; 2 forage particle lengths (FPL) of alfalfa silage (short and long) were combined with low (35:65) and high (60:40) forage:concentrate (F:C) ratios [dry matter (DM) basis]. Dietary peNDF content (DM basis) was determined from the sum of the proportion of dietary DM retained on either the 2 sieves (8 and 19 mm) or the 3 sieves (1.18, 8, and 19 mm) of the Penn State Particle Separator multiplied by the NDF content of the diet. The dietary peNDF contents ranged from 9.6 to 19.8% using 2 sieves, or from 28.6 to 34.0% using 3 sieves. Intake of peNDF was increased by increasing both the F:C ratio and the FPL of the diets. However, F:C ratio and FPL affected chewing activity differently; increasing F:C ratio increased chewing time but increasing FPL only increased chewing when a high-forage diet was fed. Mean ruminal pH was increased by 0.5 and 0.2 units with increasing F:C ratio and FPL, respectively. Cows fed the low F:C diet had > 10 or 7 h daily in which ruminal pH was below 5.8 or 5.5, respectively, compared with 1.2 and 0.1 h for cows fed the high F:C ratio diet. Increased F:C ratio reduced ruminal VFA concentration from 135 to 121 mM but increased the acetate:propionate ratio from 1.82 to 3.13. Dietary peNDF content when measured using 2 sieves was positively correlated to chewing time (r = 0.61) and mean ruminal pH (r = 0.73), and negatively correlated to the time that pH was below 5.8 or 5.5 (r = -0.46). This study shows that the risk of ruminal acidosis is high for cows fed a low F:C diet, particularly when finely chopped silage is used. Intake of dietary peNDF is a good indicator of ruminal pH status of dairy cows. Increasing the proportion of forage in the diet helps prevent ruminal acidosis through increased chewing time, a change in meal patterns, and decreased ruminal acid production. Increasing FPL elevates ruminal pH, but in low-forage diets increased FPL does not completely alleviate subacute acidosis because the fermentability of the diet is high and changes in chewing activity are marginal.

Optimisation of a honeybee-colony's energetics via social learning based on queuing delays

NASA Astrophysics Data System (ADS)

Thenius, Ronald; Schmickl, Thomas; Crailsheim, Karl

2008-06-01

Natural selection shaped the foraging-related processes of honeybees in such a way that a colony can react to changing environmental conditions optimally. To investigate this complex dynamic social system, we developed a multi-agent model of the nectar flow inside and outside of a honeybee colony. In a honeybee colony, a temporal caste collects nectar in the environment. These foragers bring their harvest into the colony, where they unload their nectar loads to one or more storer bees. Our model predicts that a cohort of foragers, collecting nectar from a single nectar source, is able to detect changes in quality in other food sources they have never visited, via the nectar processing system of the colony. We identified two novel pathways of forager-to-forager communication. Foragers can gain information about changes in the nectar flow in the environment via changes in their mean waiting time for unloadings and the number of experienced multiple unloadings. This way two distinct groups of foragers that forage on different nectar sources and that never communicate directly can share information via a third cohort of worker bees. We show that this noisy and loosely knotted social network allows a colony to perform collective information processing, so that a single forager has all necessary information available to be able to 'tune' its social behaviour, like dancing or dance-following. This way the net nectar gain of the colony is increased.

Foraging recruitment by the Giant Tropical Ant Paraponera clavata (Hymenoptera, Formicidae)

USGS Publications Warehouse

Barrett, Bruce A.; Jorgenson, Clive D.; Looman, Sandra J.

1985-01-01

Increased foraging of an exceptionally abundant, but ephemeral, food source by ants can result from foraging excitement that does not include pheromone trails, tandem running, or from recruitment of other workers along pheromone trails (Carrol and Janzen, 1973). They also provided rationale for two types of short-lived pheromone trails resulting in mass or group recruitment. These both seem to fall into the Type II foraging strategy described by Oster and Wilson (1978). Neither of these discussions conveniently allow for pheromone recruitment by relatively small colonies of a primitive monomorphic species such as Paraponera clavata. Our observations suggest that recruitment to an abundant ephemeral food source does occur naturally and can be induced artificially in colonies of P. clavata.Paraponera clavata is considered primitive (Wilson, 1958), particularly in foraging habits (Young and Hermann, 1980; Young, 1977). Hermann (1973, 1975) reported the P. clavata, unlike more advanced species, forages independently; following shot periods of apparent group activity outside of the colony (Young and Hermann, 1980). It reportedly does not return to a food source when only part has been harvested. After returning to its colony with booty, a single worker resumes foraging independently, with no observable tendency to return to partially harvested booty or without recruiting additional workers to collect the remaining food (Hermann, 1973; Young and Hermann, 1980). Reports of independent foraging, lack of forager recruitment, and apparent lack of food source fidelity resulted in the assumption that P. clavata probably lacks an effective pheromone trail communication system (Young and Hermann, 1980).

Using diel movement behavior to infer foraging strategies related to ecological and social factors in elephants.

PubMed

Polansky, Leo; Douglas-Hamilton, Iain; Wittemyer, George

2013-01-01

Adaptive movement behaviors allow individuals to respond to fluctuations in resource quality and distribution in order to maintain fitness. Classically, studies of the interaction between ecological conditions and movement behavior have focused on such metrics as travel distance, velocity, home range size or patch occupancy time as the salient metrics of behavior. Driven by the emergence of very regular high frequency data, more recently the importance of interpreting the autocorrelation structure of movement as a behavioral metric has become apparent. Studying movement of a free ranging African savannah elephant population, we evaluated how two movement metrics, diel displacement (DD) and movement predictability (MP - the degree of autocorrelated movement activity at diel time scales), changed in response to variation in resource availability as measured by the Normalized Difference Vegetation Index. We were able to capitalize on long term (multi-year) yet high resolution (hourly) global positioning system tracking datasets, the sample size of which allows robust analysis of complex models. We use optimal foraging theory predictions as a framework to interpret our results, in particular contrasting the behaviors across changes in social rank and resource availability to infer which movement behaviors at diel time scales may be optimal in this highly social species. Both DD and MP increased with increasing forage availability, irrespective of rank, reflecting increased energy expenditure and movement predictability during time periods of overall high resource availability. However, significant interactions between forage availability and social rank indicated a stronger response in DD, and a weaker response in MP, with increasing social status. Relative to high ranking individuals, low ranking individuals expended more energy and exhibited less behavioral movement autocorrelation during lower forage availability conditions, likely reflecting sub-optimal movement behavior. Beyond situations of contest competition, rank status appears to influence the extent to which individuals can modify their movement strategies across periods with differing forage availability. Large-scale spatiotemporal resource complexity not only impacts fine scale movement and optimal foraging strategies directly, but likely impacts rates of inter- and intra-specific interactions and competition resulting in socially based movement responses to ecological dynamics.

Depletion of deep marine food patches forces divers to give up early.

PubMed

Thums, Michele; Bradshaw, Corey J A; Sumner, Michael D; Horsburgh, Judy M; Hindell, Mark A

2013-01-01

Many optimal foraging models for diving animals examine strategies that maximize time spent in the foraging zone, assuming that prey acquisition increases linearly with search time. Other models have considered the effect of patch quality and predict a net energetic benefit if dives where no prey is encountered early in the dive are abandoned. For deep divers, however, the energetic benefit of giving up is reduced owing to the elevated energy costs associated with descending to physiologically hostile depths, so patch residence time should be invariant. Others consider an asymptotic gain function where the decision to leave a patch is driven by patch-depletion effects - the marginal value theorem. As predator behaviour is increasingly being used as an index of marine resource density and distribution, it is important to understand the nature of this gain function. We investigated the dive behaviour of the world's deepest-diving seal, the southern elephant seal Mirounga leonina, in response to patch quality. Testing these models has largely been limited to controlled experiments on captive animals. By integrating in situ measurements of the seal's relative lipid content obtained from drift rate data (a measure of foraging success) with area-restricted search behaviour identified from first-passage time analysis, we identified regions of high- and low-quality patches. Dive durations and bottom times were not invariant and did not increase in regions of high quality; rather, both were longer when patches were of relatively low quality. This is consistent with the predictions of the marginal value theorem and provides support for a nonlinear relationship between search time and prey acquisition. We also found higher descent and ascent rates in high-quality patches suggesting that seals minimized travel time to the foraging patch when quality was high; however, this was not achieved by increasing speed or dive angle. Relative body lipid content was an important predictor of dive behaviour. Seals did not schedule their diving to maximize time spent in the foraging zone in higher-quality patches, challenging the widely held view that maximizing time in the foraging zone translates to greater foraging success. © 2012 The Authors. Journal of Animal Ecology © 2012 British Ecological Society.

Individual variation in baseline and stress-induced corticosterone and prolactin levels predicts parental effort by nesting mourning doves

USGS Publications Warehouse

Miller, David A.; Vleck, Carol M.; Otis, David L.

2009-01-01

Endocrine systems have an important mechanistic role in structuring life-history trade-offs. During breeding, individual variation in prolactin (PRL) and corticosterone (CORT) levels affects behavioral and physiological processes that drive trade-offs between reproduction and self-maintenance. We examined patterns in baseline (BL) and stress induced (SI; level following a standard capture-restraint protocol) levels of PRL and CORT for breeding mourning doves (Zenaida macroura). We determined whether the relationship of adult condition and parental effort to hormone levels in wild birds was consistent with life-history predictions. Both BL PRL and BL CORT level in adults were positively related to nestling weight at early nestling ages, consistent with the prediction of a positive relationship of hormone levels to current parental effort of adults and associated increased energy demand. Results are consistent with the two hormones acting together at baseline levels to limit negative effects of CORT on reproduction while maintaining beneficial effects such as increased foraging for nestling feeding. Our data did not support predictions that SI responses would vary in response to nestling or adult condition. The magnitude of CORT response in the parents to our capture-restraint protocol was negatively correlated with subsequent parental effort. Average nestling weights for adults with the highest SI CORT response were on average 10–15% lighter than expected for their age in follow-up visits after the stress event. Our results demonstrated a relationship between individual hormone levels and within population variation in parental effort and suggested that hormonal control plays an important role in structuring reproductive decisions for mourning doves.

Individual variation in baseline and stress-induced corticosterone and prolactin levels predicts parental effort by nesting mourning doves

USGS Publications Warehouse

Miller, David A.; Vleck, Carol M.; Otis, David L.

2009-01-01

Endocrine systems have an important mechanistic role in structuring life-history trade-offs. During breeding, individual variation in prolactin (PRL) and corticosterone (CORT) levels affects behavioral and physiological processes that drive trade-offs between reproduction and self-maintenance. We examined patterns in baseline (BL) and stress induced (SI; level following a standard capture-restraint protocol) levels of PRL and CORT for breeding mourning doves (Zenaida macroura). We determined whether the relationship of adult condition and parental effort to hormone levels in wild birds was consistent with life-history predictions. Both BL PRL and BL CORT level in adults were positively related to nestling weight at early nestling ages, consistent with the prediction of a positive relationship of hormone levels to current parental effort of adults and associated increased energy demand. Results are consistent with the two hormones acting together at baseline levels to limit negative effects of CORT on reproduction while maintaining beneficial effects such as increased foraging for nestling feeding. Our data did not support predictions that SI responses would vary in response to nestling or adult condition. The magnitude of CORT response in the parents to our capture-restraint protocol was negatively correlated with subsequent parental effort. Average nestling weights for adults with the highest SI CORT response were on average 10–15% lighter than expected for their age in follow-up visits after the stress event. Our results demonstrated a relationship between individual hormone levels and within population variation in parental effort and suggested that hormonal control plays an important role in structuring reproductive decisions for mourning doves.

Bumble bee nest abundance, foraging distance, and host-plant reproduction: implications for management and conservation.

PubMed

Geib, Jennifer C; Strange, James P; Galenj, Candace

2015-04-01

Recent reports of global declines in pollinator species imply an urgent need to assess the abundance of native pollinators and density-dependent benefits for linked plants. In this study, we investigated (1) pollinator nest distributions and estimated colony abundances, (2) the relationship between abundances of foraging workers and the number of nests they represent, (3) pollinator foraging ranges, and (4) the relationship between pollinator abundance and plant reproduction. We examined these questions in an alpine ecosystem in the Colorado Rocky Mountains, focusing on four alpine bumble bee species (Bombus balteatus, B. flavifrons, B. bifarius, and B. sylvicola), and two host plants that differ in their degrees of pollinator specialization (Trifolium dasyphyllum and T. parryi). Using microsatellites, we found that estimated colony abundances among Bombus species ranged from ~18 to 78 colonies/0.01 km2. The long-tongued species B. balteatus was most common, especially high above treeline, but the subalpine species B. bifarius was unexpectedly abundant for this elevation range. Nests detected among sampled foragers of each species were correlated with the number of foragers caught. Foraging ranges were smaller than expected for all Bombus species, ranging from 25 to 110 m. Fruit set for the specialized plant, Trifolium parryi, was positively related to the abundance of its Bombus pollinator. In contrast, fruit set for the generalized plant, T. dasyphyllum, was related to abundance of all Bombus species. Because forager abundance was related to nest abundance of each Bombus species and was an equally effective predictor of plant fecundity, forager inventories are probably suitable for assessing the health of outcrossing plant populations. However, nest abundance, rather than forager abundance, better reflects demographic and genetic health in populations of eusocial pollinators such as bumble bees. Development of models incorporating the parameters we have measured here (nest abundance, forager abundance, and foraging distance) could increase the usefulness of foraging worker inventories in nionitoring, managing, and conserving pollinator populations.

Air pollutants degrade floral scents and increase insect foraging times

NASA Astrophysics Data System (ADS)

Fuentes, Jose D.; Chamecki, Marcelo; Roulston, T.'ai; Chen, Bicheng; Pratt, Kenneth R.

2016-09-01

Flowers emit mixtures of scents that mediate plant-insect interactions such as attracting insect pollinators. Because of their volatile nature, however, floral scents readily react with ozone, nitrate radical, and hydroxyl radical. The result of such reactions is the degradation and the chemical modification of scent plumes downwind of floral sources. Large Eddy Simulations (LES) are developed to investigate dispersion and chemical degradation and modification of floral scents due to reactions with ozone, hydroxyl radical, and nitrate radical within the atmospheric surface layer. Impacts on foraging insects are investigated by utilizing a random walk model to simulate insect search behavior. Results indicate that even moderate air pollutant levels (e.g., ozone mixing ratios greater than 60 parts per billion on a per volume basis, ppbv) substantially degrade floral volatiles and alter the chemical composition of released floral scents. As a result, insect success rates of locating plumes of floral scents were reduced and foraging times increased in polluted air masses due to considerable degradation and changes in the composition of floral scents. Results also indicate that plant-pollinator interactions could be sensitive to changes in floral scent composition, especially if insects are unable to adapt to the modified scentscape. The increase in foraging time could have severe cascading and pernicious impacts on the fitness of foraging insects by reducing the time devoted to other necessary tasks.

Assessing honeybee and wasp thermoregulation and energetics—New insights by combination of flow-through respirometry with infrared thermography

PubMed Central

Stabentheiner, Anton; Kovac, Helmut; Hetz, Stefan K.; Käfer, Helmut; Stabentheiner, Gabriel

2012-01-01

Endothermic insects like honeybees and some wasps have to cope with an enormous heat loss during foraging because of their small body size in comparison to endotherms like mammals and birds. The enormous costs of thermoregulation call for optimisation. Honeybees and wasps differ in their critical thermal maximum, which enables the bees to kill the wasps by heat. We here demonstrate the benefits of a combined use of body temperature measurement with infrared thermography, and respiratory measurements of energy turnover (O2 consumption or CO2 production via flow-through respirometry) to answer questions of insect ecophysiological research, and we describe calibrations to receive accurate results. To assess the question of what foraging honeybees optimise, their body temperature was compared with their energy turnover. Honeybees foraging from an artificial flower with unlimited sucrose flow increased body surface temperature and energy turnover with profitability of foraging (sucrose content of the food; 0.5 or 1.5 mol/L). Costs of thermoregulation, however, were rather independent of ambient temperature (13–30 °C). External heat gain by solar radiation was used to increase body temperature. This optimised foraging energetics by increasing suction speed. In determinations of insect respiratory critical thermal limits, the combined use of respiratory measurements and thermography made possible a more conclusive interpretation of respiratory traces. PMID:22723718

Effect of corn dry distiller grains plus solubles supplementation level on performance and digestion characteristics of steers grazing native range during forage growing season.

PubMed

Martínez-Pérez, M F; Calderón-Mendoza, D; Islas, A; Encinias, A M; Loya-Olguín, F; Soto-Navarro, S A

2013-03-01

Two experiments were conducted to evaluate effects of corn dry distiller grains plus condensed solubles (DDGS) supplementation level on performance digestion characteristics of steers grazing native range during the forage growing season. In the performance study, 72 (206 ± 23.6 kg; 2008) and 60 (230 ± 11.3 kg; 2009) English crossbred steer calves were used in a randomized complete block design replicated over 2 yr. The grazing periods lasted 56 and 58 d and started on August 11 and 18 for 2008 and 2009, respectively. Each year, steers were blocked by BW (light, medium, and heavy), stratified by BW within blocks, and randomly assigned to 1 of 4 grazing groups. Each grazing group (6 steers in 2008 and 5 in 2009) was assigned to a DDGS supplementation levels (0, 0.2, 0.4, and 0.6% BW). Grazing group served as the experimental unit with 12 groups per year receiving 1 of 4 treatments for 2 yr (n = 6). In the metabolism study, 16 English crossbred steers (360 ± 28.9 kg) fitted with ruminal cannulas grazing native range during the summer growing season were used in a completely randomized design to evaluate treatment effects on forage intake and digestion. The experiment was conducted during the first and second weeks of October 2008. Steers were randomly assigned to supplement level (0, 0.2, 0.4, and 0.6% BW; n = 4) and grazed a single native range pasture with supplements offered individually once daily at 0700 h. In the performance study, ADG (0.64, 0.75, 0.80, and 0.86 ± 0.03 kg/d for 0, 0.2, 0.4, and 0.6% BW, respectively) increased linearly (P = 0.01) with increasing DDGS supplementation level. In the metabolism study, forage OM, NDF, CP, and ether extract (EE) intake decreased (P ≤ 0.05) linearly with increasing DDGS supplementation level. Total CP and EE intake increased (P ≤ 0.002) with increasing DDGS supplementation level. Digestibility of OM, NDF, and EE increased (linear; P ≤ 0.008) whereas the soluble CP fraction of forage masticate sample linearly increased (P = 0.01) and slowly degradable CP fraction linearly decreased (P = 0.05) with increasing DDGS supplementation level. Forage in situ masticate DM and NDF disappearance rate decreased (quadratic; P ≤ 0.05) and DDGS in situ DM disappearance rate increased (linear; P = 0.03) with increasing supplementation levels. These results indicate that DDGS supplementation enhanced grazing performance and total-tract digestion of steers grazing native range during the forage growing season.

Effect of restricted forage intake on ruminal disappearance of bromegrass hay and a blood meal, feather meal, and fish meal supplement.

PubMed

Scholljegerdes, E J; Ludden, P A; Hess, B W

2005-09-01

Two experiments were conducted to determine in situ disappearance of bromegrass hay and a ruminally undegraded protein (RUP) supplement in beef cattle fed restricted amounts of forage. Six Angus crossbred cattle (BW = 589 +/- 44.4 kg; three steers and three heifers) fitted with ruminal cannulas were fed chopped (2.54 cm) bromegrass hay (8.9% CP) at one of three percentages of maintenance intake (30, 55, or 80%; one steer and one heifer per treatment). In both experiments, the cattle were allowed 7 d for diet adaptation followed by 3 d of sample collection. In Exp 1, in situ bags (50 microm pore size) containing 4.1 g of brome-grass hay (OM basis) were inserted into the rumen and subsequently removed at 3, 6, 9, 12, 15, 18, 24, 36, and 48 h after insertion. Nonlinear regression models were used to determine the rapidly solubilized protein Fraction A, the potentially ruminal degradable protein Fraction B, the ruminally undegraded protein Fraction C, and protein degradation rate. Intake level did not affect (P = 0.15 to 0.95) forage protein remaining after in situ incubation or Fractions A, B, and C; however, effective ruminal degradation of hay protein tended to increase quadratically (P = 0.12) as forage intake increased. In Exp 2, 4.2 g (OM basis) of an RUP supplement (6.8% porcine blood meal, 24.5% hydrolyzed feather meal, and 68.7% menhaden fish meal) formulated to provide equal amounts of metabolizable protein across all levels of hay consumption was evaluated in a similar manner as in Exp 1. The undegraded protein fraction of the supplement did not differ (P = 0.16 to 0.74) across treatments at 3, 6, 9, and 18 h; however, increasing forage intake resulted in a linear increase (P < or = 0.06) in undegraded protein remaining at 12, 15, 24, 36, and 48 h. Dietary treatment had no affect (P = 0.30) on protein Fractions A, B, or C; however, protein degradation rate of the supplement decreased linearly (P = 0.03) as forage intake increased. Therefore, effective ruminal degradation of the supplement decreased linearly (P = 0.01) from 50.8 to 40.9% as forage intake increased from 30 to 80% of maintenance. Corresponding estimates of supplement RUP were 49.2, 56.5, and 59.1% for the 30, 55, and 80% of maintenance intake treatments, respectively. Restricting dietary intake can decrease the quantity of dietary protein that escapes ruminal degradation. Tabular estimates of RUP may not be appropriate for formulating diets to balance metabolizable protein in beef cattle consuming limited quantities of forage.

Assessing Social – Ecological Trade-Offs to Advance Ecosystem-Based Fisheries Management

PubMed Central

Voss, Rudi; Quaas, Martin F.; Schmidt, Jörn O.; Tahvonen, Olli; Lindegren, Martin; Möllmann, Christian

2014-01-01

Modern resource management faces trade-offs in the provision of various ecosystem goods and services to humanity. For fisheries management to develop into an ecosystem-based approach, the goal is not only to maximize economic profits, but to consider equally important conservation and social equity goals. We introduce such a triple-bottom line approach to the management of multi-species fisheries using the Baltic Sea as a case study. We apply a coupled ecological-economic optimization model to address the actual fisheries management challenge of trading-off the recovery of collapsed cod stocks versus the health of ecologically important forage fish populations. Management strategies based on profit maximization would rebuild the cod stock to high levels but may cause the risk of stock collapse for forage species with low market value, such as Baltic sprat (Fig. 1A). Economically efficient conservation efforts to protect sprat would be borne almost exclusively by the forage fishery as sprat fishing effort and profits would strongly be reduced. Unless compensation is paid, this would challenge equity between fishing sectors (Fig. 1B). Optimizing equity while respecting sprat biomass precautionary levels would reduce potential profits of the overall Baltic fishery, but may offer an acceptable balance between overall profits, species conservation and social equity (Fig. 1C). Our case study shows a practical example of how an ecosystem-based fisheries management will be able to offer society options to solve common conflicts between different resource uses. Adding equity considerations to the traditional trade-off between economy and ecology will greatly enhance credibility and hence compliance to management decisions, a further footstep towards healthy fish stocks and sustainable fisheries in the world ocean. PMID:25268117

Triticale for dairy forage systems

USDA-ARS?s Scientific Manuscript database

Triticale forages have become increasingly important components of dairy-cropping systems. In part, this trend has occurred in response to environmental pressures, specifically a desire to capture N and other nutrients from land-applied manure, and/or to improve stewardship of the land by providing ...

Use of Urban Marine Habitats by Foraging Wading Birds

EPA Science Inventory

Wading birds that utilize coastal habitats may be at risk from increasing urbanization near their foraging and stopover sites. However, the relative importance of human disturbance in the context of other landscape and biological factors that may be influencing their distributio...

Relationships between breeding status, social -congregation attendance, and foraging distance of xantus's murrelets

USGS Publications Warehouse

Hamilton, C.D.; Golightly, R.T.; Takekawa, John Y.

2011-01-01

At night during the breeding season, Xantus's Murrelets (Synthliboramphus hypoleucus) congregate on the water adjacent to nesting colonies. We examined relationships of attendance at these nocturnal congregations, breeding status, and daytime foraging locations of radio-marked Xantus's Murrelets from Anacapa Island (33 in 2002, 44 in 2003) and Santa Barbara Island (35 in 2002) in the California Channel Islands. Murrelets thatspent more nights attending congregations were located closer to the island during the day, so regular attendance at the congregations may have constrained daytime traveling distances to foraging locations. In mid-May 2003 home-range sizes increased while congregation attendance decreased, likely indicating the end of colony attendance and declining availability of prey near Anacapa Island. In both years, incubating murrelets foraged farther from the colony than did nonbreeding murrelets, suggesting that breeding and nonbreeding murrelets use different foraging strategies to meet their energetic requirements. Copyright ?? The Cooper Ornithological Society 2011.

Are Dispersal Mechanisms Changing the Host-Parasite Relationship and Increasing the Virulence of Varroa destructor (Mesostigmata: Varroidae) in Managed Honey Bee (Hymenoptera: Apidae) Colonies?

PubMed

DeGrandi-Hoffman, Gloria; Ahumada, Fabiana; Graham, Henry

2017-08-01

Varroa (Varroa destructor Anderson and Trueman) are a serious pest of European honey bees (Apis mellifera L.), and difficult to control in managed colonies. In our 11-mo longitudinal study, we applied multiple miticide treatments, yet mite numbers remained high and colony losses exceeded 55%. High mortality from varroa in managed apiaries is a departure from the effects of the mite in feral colonies where bees and varroa can coexist. Differences in mite survival strategies and dispersal mechanisms may be contributing factors. In feral colonies, mites can disperse through swarming. In managed apiaries, where swarming is reduced, mites disperse on foragers robbing or drifting from infested hives. Using a honey bee-varroa population model, we show that yearly swarming curtails varroa population growth, enabling colony survival for >5 yr. Without swarming, colonies collapsed by the third year. To disperse, varroa must attach to foragers that then enter other hives. We hypothesize that stress from parasitism and virus infection combined with effects that viruses have on cognitive function may contribute to forager drift and mite and virus dispersal. We also hypothesize that drifting foragers with mites can measurably increase mite populations. Simulations initialized with field data indicate that low levels of drifting foragers with mites can create sharp increases in mite populations in the fall and heavily infested colonies in the spring. We suggest new research directions to investigate factors leading to mite dispersal on foragers, and mite management strategies with consideration of varroa as a migratory pest. Published by Oxford University Press on behalf of Entomological Society of America 2017. This work is written by US Government employees and is in the public domain in the US.

The Importance of Distance to Resources in the Spatial Modelling of Bat Foraging Habitat

PubMed Central

Rainho, Ana; Palmeirim, Jorge M.

2011-01-01

Many bats are threatened by habitat loss, but opportunities to manage their habitats are now increasing. Success of management depends greatly on the capacity to determine where and how interventions should take place, so models predicting how animals use landscapes are important to plan them. Bats are quite distinctive in the way they use space for foraging because (i) most are colonial central-place foragers and (ii) exploit scattered and distant resources, although this increases flying costs. To evaluate how important distances to resources are in modelling foraging bat habitat suitability, we radio-tracked two cave-dwelling species of conservation concern (Rhinolophus mehelyi and Miniopterus schreibersii) in a Mediterranean landscape. Habitat and distance variables were evaluated using logistic regression modelling. Distance variables greatly increased the performance of models, and distance to roost and to drinking water could alone explain 86 and 73% of the use of space by M. schreibersii and R. mehelyi, respectively. Land-cover and soil productivity also provided a significant contribution to the final models. Habitat suitability maps generated by models with and without distance variables differed substantially, confirming the shortcomings of maps generated without distance variables. Indeed, areas shown as highly suitable in maps generated without distance variables proved poorly suitable when distance variables were also considered. We concluded that distances to resources are determinant in the way bats forage across the landscape, and that using distance variables substantially improves the accuracy of suitability maps generated with spatially explicit models. Consequently, modelling with these variables is important to guide habitat management in bats and similarly mobile animals, particularly if they are central-place foragers or depend on spatially scarce resources. PMID:21547076

Foraging behavior of pileated woodpeckers in partial cut and uncut bottomland hardwood forest

USGS Publications Warehouse

Newell, P.; King, Sammy L.; Kaller, Michael D.

2009-01-01

In bottomland hardwood forests, partial cutting techniques are increasingly advocated and used to create habitat for priority wildlife like Louisiana black bear (Ursus americanus luteolus), white-tailed deer (Odocoileus virginianus), and Neotropical migrants. Although partial cutting may be beneficial to some species, those that use dead wood may be negatively affected since large diameter and poor quality trees (deformed, moribund, or dead) are rare, but normally targeted for removal. On the other hand, partial cutting can create dead wood if logging slash is left on-site. We studied foraging behavior of pileated woodpeckers (Dryocopus pileatus) in one- and two-year-old partial cuts designed to benefit priority species and in uncut forest during winter, spring, and summer of 2006 and 2007 in Louisiana. Males and females did not differ in their use of tree species, dbh class, decay class, foraging height, use of foraging tactics or substrate types; however, males foraged on larger substrates than females. In both partial cut and uncut forest, standing live trees were most frequently used (83% compared to 14% for standing dead trees and 3% for coarse woody debris); however, dead trees were selected (i.e. used out of proportion to availability). Overcup oak (Quercus lyrata) and bitter pecan (Carya aquatica) were also selected and sugarberry (Celtis laevigata) avoided. Pileated woodpeckers selected trees >= 50 cm dbh and avoided trees in smaller dbh classes (10-20 cm). Density of selected foraging substrates was the same in partial cut and uncut forest. Of the foraging substrates, woodpeckers spent 54% of foraging time on live branches and boles, 37% on dead branches and boles, and 9% on vines. Of the foraging tactics, the highest proportion of foraging time was spent excavating (58%), followed by pecking (14%), gleaning (14%), scaling (7%), berry-eating (4%), and probing (3%). Woodpecker use of foraging tactics and substrates, and foraging height and substrate diameter did not differ between recent partial cut and uncut forest. Partial cutting designed to improve or maintain habitat for priority wildlife did not affect pileated woodpecker foraging behavior or availability of selected trees compared to uncut forest in the short term.

Foraging behavior of pileated woodpeckers in partial cut and uncut bottomland hardwood forest

USGS Publications Warehouse

Newell, P.; King, S.; Kaller, M.

2009-01-01

In bottomland hardwood forests, partial cutting techniques are increasingly advocated and used to create habitat for priority wildlife like Louisiana black bear (Ursus americanus luteolus), white-tailed deer (Odocoileus virginianus), and Neotropical migrants. Although partial cutting may be beneficial to some species, those that use dead wood may be negatively affected since large diameter and poor quality trees (deformed, moribund, or dead) are rare, but normally targeted for removal. On the other hand, partial cutting can create dead wood if logging slash is left on-site. We studied foraging behavior of pileated woodpeckers (Dryocopus pileatus) in one- and two-year-old partial cuts designed to benefit priority species and in uncut forest during winter, spring, and summer of 2006 and 2007 in Louisiana. Males and females did not differ in their use of tree species, dbh class, decay class, foraging height, use of foraging tactics or substrate types; however, males foraged on larger substrates than females. In both partial cut and uncut forest, standing live trees were most frequently used (83% compared to 14% for standing dead trees and 3% for coarse woody debris); however, dead trees were selected (i.e. used out of proportion to availability). Overcup oak (Quercus lyrata) and bitter pecan (Carya aquatica) were also selected and sugarberry (Celtis laevigata) avoided. Pileated woodpeckers selected trees ???50 cm dbh and avoided trees in smaller dbh classes (10-20 cm). Density of selected foraging substrates was the same in partial cut and uncut forest. Of the foraging substrates, woodpeckers spent 54% of foraging time on live branches and boles, 37% on dead branches and boles, and 9% on vines. Of the foraging tactics, the highest proportion of foraging time was spent excavating (58%), followed by pecking (14%), gleaning (14%), scaling (7%), berry-eating (4%), and probing (3%). Woodpecker use of foraging tactics and substrates, and foraging height and substrate diameter did not differ between recent partial cut and uncut forest. Partial cutting designed to improve or maintain habitat for priority wildlife did not affect pileated woodpecker foraging behavior or availability of selected trees compared to uncut forest in the short term. ?? 2009 Elsevier B.V.

Hunting behaviour and breeding performance of northern goshawks Accipiter gentilis, in relation to resource availability, sex, age and morphology

NASA Astrophysics Data System (ADS)

Penteriani, Vincenzo; Rutz, Christian; Kenward, Robert

2013-10-01

Animal territories that differ in the availability of food resources will require (all other things being equal) different levels of effort for successful reproduction. As a consequence, breeding performance may become most strongly dependent on factors that affect individual foraging where resources are poor. We investigated potential links between foraging behaviour, reproductive performance and morphology in a goshawk Accipiter gentilis population, which experienced markedly different resource levels in two different parts of the study area (rabbit-rich vs. rabbit-poor areas). Our analyses revealed (1) that rabbit abundance positively affected male reproductive output; (2) that age, size and rabbit abundance (during winter) positively affected different components of female reproductive output; (3) that foraging movements were inversely affected by rabbit abundance for both sexes (for females, this may mainly have reflected poor provisioning by males in the rabbit-poor area); (4) that younger breeders (both in males and females) tended to move over larger distances than older individuals (which may have reflected both a lack of hunting experience and mate searching); and (5) that male body size (wing length) showed some covariation with resource conditions (suggesting possible adaptations to hunting agile avian prey in the rabbit-poor area). Although we are unable to establish firm causal relationships with our observational data set, our results provide an example of how territory quality (here, food abundance) and individual features (here, age and morphology) may combine to shape a predator's foraging behaviour and, ultimately, its breeding performance.

Foraging behavior of lactating South American sea lions (Otaria flavescens) and spatial-temporal resource overlap with the Uruguayan fisheries

NASA Astrophysics Data System (ADS)

Riet-Sapriza, Federico G.; Costa, Daniel P.; Franco-Trecu, Valentina; Marín, Yamandú; Chocca, Julio; González, Bernardo; Beathyate, Gastón; Louise Chilvers, B.; Hückstadt, Luis A.

2013-04-01

Resource competition between fisheries and marine mammal continue to raise concern worldwide. Understanding this complex conflict requires data on spatial and dietary overlap of marine mammal and fisheries. In Uruguay the South American sea lions population has been dramatically declining over the past decade. The reasons for this population decline are unknown but may include the following: (1) direct harvesting; (2) reduced prey availability and distribution as a consequence of environmental change; or (3) biological interaction with fisheries. This study aims to determine resource overlap and competition between South American sea lions (SASL, Otaria flavescens, n=10) and the artisanal fisheries (AF), and the coastal bottom trawl fisheries (CBTF). We integrated data on sea lions diet (scat analysis), spatial and annual consumption estimates; and foraging behavior-satellite-tracking data from lactating SASL with data on fishing effort areas and fisheries landings. We found that lactating SASL are benthic divers and forage in shallow water within the continental shelf. SASL's foraging areas overlapped with CBTF and AF fisheries operational areas. Dietary analysis indicated a high degree of overlap between the diet of SASL and the AF and CBTF fisheries catch. The results of our work show differing degrees of spatial resource overlap with AF and CBTF, highlighting that there are differences in potential impact from each fishery; and that different management/conservation approaches may need to be taken to solve the fisheries-SASL conflict.

Deep-water feeding and behavioral plasticity in Manta birostris revealed by archival tags and submersible observations.

PubMed

Stewart, Joshua D; Hoyos-Padilla, Edgar Mauricio; Kumli, Katherine R; Rubin, Robert D

2016-10-01

Foraging drives many fundamental aspects of ecology, and an understanding of foraging behavior aids in the conservation of threatened species by identifying critical habitats and spatial patterns relevant to management. The world's largest ray, the oceanic manta (Manta birostris) is poorly studied and threatened globally by targeted fisheries and incidental capture. Very little information is available on the natural history, ecology and behavior of the species, complicating management efforts. This study provides the first data on the diving behavior of the species based on data returned from six tagged individuals, and an opportunistic observation from a submersible of a manta foraging at depth. Pop-off archival satellite tags deployed on mantas at the Revillagigedo Archipelago, Mexico recorded seasonal shifts in diving behavior, likely related to changes in the location and availability of zooplankton prey. Across seasons, mantas spent a large proportion of their time centered around the upper limit of the thermocline, where zooplankton often aggregate. Tag data reveal a gradual activity shift from surface waters to 100-150m across the tagging period, possibly indicating a change in foraging behavior from targeting surface-associated zooplankton to vertical migrators. The depth ranges accessed by mantas in this study carry variable bycatch risks from different fishing gear types. Consequently, region-specific data on diving behavior can help inform local management strategies that reduce or mitigate bycatch of this vulnerable species. Copyright © 2016 Elsevier GmbH. All rights reserved.

Characteristics of foraging sites and protein status in wintering muskoxen: insights from isotopes of nitrogen

USGS Publications Warehouse

Gustine, David D.; Barboza, Perry S.; Lawler, James P.; Arthur, Stephen M.; Shults, Brad S.; Persons, Kate; Adams, Layne G.

2011-01-01

Identifying links between nutritional condition of individuals and population trajectories greatly enhances our understanding of the ecology, conservation, and management of wildlife. For northern ungulates, the potential impacts of a changing climate to populations are predicted to be nutritionally mediated through an increase in the severity and variance in winter conditions. Foraging conditions and the availability of body protein as a store for reproduction in late winter may constrain productivity in northern ungulates, yet the link between characteristics of wintering habitats and protein status has not been established for a wild ungulate. We used a non‐invasive proxy of protein status derived from isotopes of N in excreta to evaluate the influence of winter habitats on the protein status of muskoxen in three populations in Alaska (2005–2008). Multiple regression and an information‐theoretic approach were used to compare models that evaluated the influence of population, year, and characteristics of foraging sites (components of diet and physiography) on protein status for groups of muskoxen. The observed variance in protein status among groups of muskoxen across populations and years was partially explained (45%) by local foraging conditions that affected forage availability. Protein status improved for groups of muskoxen as the amount of graminoids in the diet increased (−0.430 ± 0.31, β± 95% CI) and elevation of foraging sites decreased (0.824 ± 0.67). Resources available for reproduction in muskoxen are highly dependent upon demographic, environmental, and physiographic constraints that affect forage availability in winter. Due to their very sedentary nature in winter, muskoxen are highly susceptible to localized foraging conditions; therefore, the spatial variance in resource availability may exert a strong effect on productivity. Consequently, there is a clear need to account for climate–topography effects in winter at multiple scales when predicting the potential impacts of climatic shifts on population trajectories of muskoxen.

A Strong Immune Response in Young Adult Honeybees Masks Their Increased Susceptibility to Infection Compared to Older Bees

PubMed Central

Bull, James C.; Ryabov, Eugene V.; Prince, Gill; Mead, Andrew; Zhang, Cunjin; Baxter, Laura A.; Pell, Judith K.; Osborne, Juliet L.; Chandler, Dave

2012-01-01

Honeybees, Apis mellifera, show age-related division of labor in which young adults perform maintenance (“housekeeping”) tasks inside the colony before switching to outside foraging at approximately 23 days old. Disease resistance is an important feature of honeybee biology, but little is known about the interaction of pathogens and age-related division of labor. We tested a hypothesis that older forager bees and younger “house” bees differ in susceptibility to infection. We coupled an infection bioassay with a functional analysis of gene expression in individual bees using a whole genome microarray. Forager bees treated with the entomopathogenic fungus Metarhizium anisopliae s.l. survived for significantly longer than house bees. This was concomitant with substantial differences in gene expression including genes associated with immune function. In house bees, infection was associated with differential expression of 35 candidate immune genes contrasted with differential expression of only two candidate immune genes in forager bees. For control bees (i.e. not treated with M. anisopliae) the development from the house to the forager stage was associated with differential expression of 49 candidate immune genes, including up-regulation of the antimicrobial peptide gene abaecin, plus major components of the Toll pathway, serine proteases, and serpins. We infer that reduced pathogen susceptibility in forager bees was associated with age-related activation of specific immune system pathways. Our findings contrast with the view that the immunocompetence in social insects declines with the onset of foraging as a result of a trade-off in the allocation of resources for foraging. The up-regulation of immune-related genes in young adult bees in response to M. anisopliae infection was an indicator of disease susceptibility; this also challenges previous research in social insects, in which an elevated immune status has been used as a marker of increased disease resistance and fitness without considering the effects of age-related development. PMID:23300441

Ocean sunfish rewarm at the surface after deep excursions to forage for siphonophores.

PubMed

Nakamura, Itsumi; Goto, Yusuke; Sato, Katsufumi

2015-05-01

Ocean sunfish (Mola mola) were believed to be inactive jellyfish feeders because they are often observed lying motionless at the sea surface. Recent tracking studies revealed that they are actually deep divers, but there has been no evidence of foraging in deep water. Furthermore, the surfacing behaviour of ocean sunfish was thought to be related to behavioural thermoregulation, but there was no record of sunfish body temperature. Evidence of ocean sunfish feeding in deep water was obtained using a combination of an animal-borne accelerometer and camera with a light source. Siphonophores were the most abundant prey items captured by ocean sunfish and were typically located at a depth of 50-200 m where the water temperature was <12 °C. Ocean sunfish were diurnally active, made frequently deep excursions and foraged mainly at 100-200 m depths during the day. Ocean sunfish body temperatures were measured under natural conditions. The body temperatures decreased during deep excursions and recovered during subsequent surfacing periods. Heat-budget models indicated that the whole-body heat-transfer coefficient between sunfish and the surrounding water during warming was 3-7 times greater than that during cooling. These results suggest that the main function of surfacing is the recovery of body temperature, and the fish might be able to increase heat gain from the warm surface water by physiological regulation. The thermal environment of ocean sunfish foraging depths was lower than their thermal preference (c. 16-17 °C). The behavioural and physiological thermoregulation enables the fish to increase foraging time in deep, cold water. Feeding rate during deep excursions was not related to duration or depth of the deep excursions. Cycles of deep foraging and surface warming were explained by a foraging strategy, to maximize foraging time with maintaining body temperature by vertical temperature environment. © 2015 The Authors. Journal of Animal Ecology © 2015 British Ecological Society.

Balancing energy budget in a central-place forager: which habitat to select in a heterogeneous environment?

PubMed

Patenaude-Monette, Martin; Bélisle, Marc; Giroux, Jean-François

2014-01-01

Foraging animals are influenced by the distribution of food resources and predation risk that both vary in space and time. These constraints likely shape trade-offs involving time, energy, nutrition, and predator avoidance leading to a sequence of locations visited by individuals. According to the marginal-value theorem (MVT), a central-place forager must either increase load size or energy content when foraging farther from their central place. Although such a decision rule has the potential to shape movement and habitat selection patterns, few studies have addressed the mechanisms underlying habitat use at the landscape scale. Our objective was therefore to determine how Ring-billed gulls (Larus delawarensis) select their foraging habitats while nesting in a colony located in a heterogeneous landscape. Based on locations obtained by fine-scale GPS tracking, we used resource selection functions (RSFs) and residence time analyses to identify habitats selected by gulls for foraging during the incubation and brood rearing periods. We then combined this information to gull survey data, feeding rates, stomach contents, and calorimetric analyses to assess potential trade-offs. Throughout the breeding season, gulls selected landfills and transhipment sites that provided higher mean energy intake than agricultural lands or riparian habitats. They used landfills located farther from the colony where no deterrence program had been implemented but avoided those located closer where deterrence measures took place. On the other hand, gulls selected intensively cultured lands located relatively close to the colony during incubation. The number of gulls was then greater in fields covered by bare soil and peaked during soil preparation and seed sowing, which greatly increase food availability. Breeding Ring-billed gulls thus select habitats according to both their foraging profitability and distance from their nest while accounting for predation risk. This supports the predictions of the MVT for central-place foraging over large spatial scales.

Evidence for density dependence in foraging and migratory behavior of a subtropical nearshore seabird

USGS Publications Warehouse

Lamb, Juliet S.; Satgé, Yvan G.; Jodice, Patrick G. R.

2017-01-01

Density-dependent competition for food resources influences both foraging ecology and reproduction in a variety of animals. The relationship between colony size, local prey depletion, and reproductive output in colonial central-place foragers has been extensively studied in seabirds; however, most studies have focused on effects of intraspecific competition during the breeding season, while little is known about whether density-dependent resource depletion influences individual migratory behavior outside the breeding season. Using breeding colony size as a surrogate for intraspecific resource competition, we tested for effects of colony size on breeding home range, nestling health, and migratory patterns of a nearshore colonial seabird, the brown pelican (Pelecanus occidentalis), originating from seven breeding colonies of varying sizes in the subtropical northern Gulf of Mexico. We found evidence for density-dependent effects on foraging behavior during the breeding season, as individual foraging areas increased linearly with the number of breeding pairs per colony. Contrary to our predictions, however, nestlings from more numerous colonies with larger foraging ranges did not experience either decreased condition or increased stress. During nonbreeding, individuals from larger colonies were more likely to migrate, and traveled longer distances, than individuals from smaller colonies, indicating that the influence of density-dependent effects on distribution persists into the nonbreeding period. We also found significant effects of individual physical condition, particularly body size, on migratory behavior, which in combination with colony size suggesting that dominant individuals remain closer to breeding sites during winter. We conclude that density-dependent competition may be an important driver of both the extent of foraging ranges and the degree of migration exhibited by brown pelicans. However, the effects of density-dependent competition on breeding success and population regulation remain uncertain in this system.

Climate-driven Sympatry does not Lead to Foraging Competition Between Adélie and Gentoo Penguins

NASA Astrophysics Data System (ADS)

Cimino, M. A.; Moline, M. A.; Fraser, W.; Patterson-Fraser, D.; Oliver, M. J.

2016-02-01

Climate-driven sympatry may lead to competition for food resources between species, population shifts and changes in ecosystem structure. Rapid warming in the West Antarctic Peninsula (WAP) is coincident with increasing gentoo penguin and decreasing Adélie penguin populations, suggesting that competition for food may exacerbate the Adélie penguin decline. At Palmer Station, we tested for foraging competition between these species by comparing their prey, Antarctic krill, distributions and penguin foraging behaviors on fine scales. To study these predator-prey dynamics, we simultaneously deployed penguin satellite transmitters, and a REMUS autonomous underwater vehicle that acoustically detected krill aggregations and measured physical and biological properties of the water column. We detected krill aggregations within the horizontal and vertical foraging ranges of Adélie and gentoo penguin. In the upper 100 m of the water column, the distribution of krill aggregations were mainly associated with CHL and light, suggesting that krill selected for habitats that balance the need to consume food and avoid predation. Adélie and gentoo penguins mainly had spatially segregated foraging areas but in areas of overlap, gentoo penguins switched foraging behavior by foraging at deeper depths, a strategy which limits competition with Adélie penguins. This suggests that climate-driven sympatry does not necessarily result in competitive exclusion. Contrary to a recent theory, which suggests that increased competition for krill is the major driver of Adélie penguin population declines, we suggest that declines in Adélie penguins along the WAP are more likely due to direct and indirect climate impacts on their life histories.

Effects of water level changes and wading bird abundance on the foraging behaviour of blacknecked storks Ephippiorhynchus asiaticus in Dudwa National Park, India.

PubMed

Maheswaran, G; Rahmani, A R

2001-09-01

The effect of water level changes and wading birds' abundance on the foraging behaviour of the blacknecked stork (BNS) Ephippiorhynchus asiaticus was studied from January 1995 to June 1997 in Dudwa National Park, Uttar Pradesh. Our observations indicate that BNS territoriality increased as food levels became depleted, resulting in increased rates of aggression towards intruders. Chasing or aggression was more intense during the early period (February and March) than the late period (April, May and June). Most of (> 50%) the aggressive encounters were observed between 0600 and 1000 h of the day. Seventeen species (including BNS) were observed interacting with BNS, throughout the study period. Most interactions were with the spoonbill, Platalea leucorodia (67.4%), followed by the whitenecked stork, Ciconia episcopus (16.6%). The distance (while foraging) between BNS and other wading birds varied significantly (P < 0.001) between years indicating that BNS and other water birds foraged at different water depths and thereby explored the wetlands fully. Spoonbills were chased often; the number varied from 1 to 43 birds. BNS occasionally accepted the presence of other wading birds, including spoonbills and started foraging amidst them. This led to successful foraging of BNS (solitary feeder). Other fish-eating bird species and their numbers also limited the food consumption of foraging BNS as they had to spend time chasing away the intruders. Availability of the preferred prey fish species, Heteropnestus fossilis, forced BNS to stay throughout the year in their respective territories. High (> 60 cm) water levels were not suitable for BNS even though the patch had high prey abundance.

Sexual differences in post-hatching Saunders's gulls: size, locomotor activity, and foraging skill.

PubMed

Yoon, Jongmin; Lee, Seung-Hee; Joo, Eun-Jin; Na, Ki-Jeong; Park, Shi-Ryong

2013-04-01

Various selection pressures induce the degree and direction of sexual size dimorphism in animals. Selection favors either larger males for contests over mates or resources, or smaller males are favored for maneuverability; whereas larger females are favored for higher fecundity, or smaller females for earlier maturation for reproduction. In the genus of Larus (seagulls), adult males are generally known to be larger in size than adult females. However, the ontogeny of sexual size dimorphism is not well understood, compared to that in adults. The present study investigates the ontogeny of sexual size dimorphism in Saunders's gulls (Larus saundersi) in captivity. We artificially incubated fresh eggs collected in Incheon, South Korea, and measured body size, locomotor activity, and foraging skill in post-hatching chicks in captivity. Our results indicated that the sexual differences in size and locomotor activity occurred with the post-hatching development. Also, larger males exhibited greater foraging skills for food acquisition than smaller females at 200 days of age. Future studies should assess how the adaptive significance of the sexual size dimorphism in juveniles is linked with sexual divergence in survival rates, intrasexual contests, or parental effort in sexes.

On salesmen and tourists: Two-step optimization in deterministic foragers

NASA Astrophysics Data System (ADS)

Maya, Miguel; Miramontes, Octavio; Boyer, Denis

2017-02-01

We explore a two-step optimization problem in random environments, the so-called restaurant-coffee shop problem, where a walker aims at visiting the nearest and better restaurant in an area and then move to the nearest and better coffee-shop. This is an extension of the Tourist Problem, a one-step optimization dynamics that can be viewed as a deterministic walk in a random medium. A certain amount of heterogeneity in the values of the resources to be visited causes the emergence of power-laws distributions for the steps performed by the walker, similarly to a Lévy flight. The fluctuations of the step lengths tend to decrease as a consequence of multiple-step planning, thus reducing the foraging uncertainty. We find that the first and second steps of each planned movement play very different roles in heterogeneous environments. The two-step process improves only slightly the foraging efficiency compared to the one-step optimization, at a much higher computational cost. We discuss the implications of these findings for animal and human mobility, in particular in relation to the computational effort that informed agents should deploy to solve search problems.

Waterbirds foods in winter-managed ricefields in Mississippi

USGS Publications Warehouse

Manley, S.W.; Kaminski, R.M.; Reinecke, K.J.; Gerard, P.D.

2004-01-01

Ricefields are important foraging habitats for waterfowl and other waterbirds in primary North American wintering regions. We conducted a large-scale experiment to test effects of post-harvest ricefield treatment, winter water management, and temporal factors on availabilities of rice, moist-soil plant seeds, aquatic invertebrates, and green forage in the Mississippi Alluvial Valley (MAV), Mississippi, USA, fall-winter 1995-1997. Our results revealed that a large decrease in rice grain occurred between harvest and early winter (79-99%), which, if generally true throughout the MAV, would have critical implications on foraging carrying capacity of ricefields for migrating and wintering waterbirds. During the remainder of winter, food resources generally were similar among treatment combinations. An exception was biomass of aquatic invertebrates, which demonstrated potential to increase by late winter in ricefields that remained flooded. We offer revised calculations of foraging carrying capacity for waterfowl in MAV ricefields and recommend continuing research and management designed to increase availability of residual rice and aquatic invertebrates in winter.

A stochastic differential equation model for the foraging behavior of fish schools.

PubMed

Tạ, Tôn Việt; Nguyen, Linh Thi Hoai

2018-03-15

Constructing models of living organisms locating food sources has important implications for understanding animal behavior and for the development of distribution technologies. This paper presents a novel simple model of stochastic differential equations for the foraging behavior of fish schools in a space including obstacles. The model is studied numerically. Three configurations of space with various food locations are considered. In the first configuration, fish swim in free but limited space. All individuals can find food with large probability while keeping their school structure. In the second and third configurations, they move in limited space with one and two obstacles, respectively. Our results reveal that the probability of foraging success is highest in the first configuration, and smallest in the third one. Furthermore, when school size increases up to an optimal value, the probability of foraging success tends to increase. When it exceeds an optimal value, the probability tends to decrease. The results agree with experimental observations.

A stochastic differential equation model for the foraging behavior of fish schools

NASA Astrophysics Data System (ADS)

Tạ, Tôn ệt, Vi; Hoai Nguyen, Linh Thi

2018-05-01

Constructing models of living organisms locating food sources has important implications for understanding animal behavior and for the development of distribution technologies. This paper presents a novel simple model of stochastic differential equations for the foraging behavior of fish schools in a space including obstacles. The model is studied numerically. Three configurations of space with various food locations are considered. In the first configuration, fish swim in free but limited space. All individuals can find food with large probability while keeping their school structure. In the second and third configurations, they move in limited space with one and two obstacles, respectively. Our results reveal that the probability of foraging success is highest in the first configuration, and smallest in the third one. Furthermore, when school size increases up to an optimal value, the probability of foraging success tends to increase. When it exceeds an optimal value, the probability tends to decrease. The results agree with experimental observations.

Sward structure and nutritive value of Alexandergrass fertilized with nitrogen.

PubMed

Salvador, Paulo R; Pötter, Luciana; Rocha, Marta G; Hundertmarck, Anelise P; Sichonany, Maria José O; Amaral Neto, Luiz G; Negrini, Mateus; Moterle, Paulo H

2016-03-01

This experiment evaluated forage production, sward structure, stocking rate, weight gain per area and nutritive value of forage as grazed by beef heifers on Alexandergrass (Urochloa plantaginea (Link) Hitch) pasture fertilized with nitrogen (N): 0; 100; 200 or 300 kg of N/ha. The experiment was a completely randomized design following a repeated measurement arrangement. The experimental animals were Angus heifers with initial age and weight of 15 months and 241.5±5 kg, respectively. The grazing method was continuous, with put-and-take stocking. N utilization, regardless of the level, increase by 25% the daily forage accumulation rate and the weight gain per area by 23%. The level of 97.2 kg N/ha leads to a higher leaf blade mass and increases by 20% the leaf:stem ratio. Alterations in sward structure changes the nutritive value of forage as grazed. The utilization of 112.7 kg of N/ha allows the highest stocking rate (2049.8 kg of BW/ha), equivalent to 7.5 heifers per hectare.

Fragmentation of nest and foraging habitat affects time budgets of solitary bees, their fitness and pollination services, depending on traits: Results from an individual-based model

PubMed Central

Settele, Josef; Dormann, Carsten F.

2018-01-01

Solitary bees are important but declining wild pollinators. During daily foraging in agricultural landscapes, they encounter a mosaic of patches with nest and foraging habitat and unsuitable matrix. It is insufficiently clear how spatial allocation of nesting and foraging resources and foraging traits of bees affect their daily foraging performance. We investigated potential brood cell construction (as proxy of fitness), number of visited flowers, foraging habitat visitation and foraging distance (pollination proxies) with the model SOLBEE (simulating pollen transport by solitary bees, tested and validated in an earlier study), for landscapes varying in landscape fragmentation and spatial allocation of nesting and foraging resources. Simulated bees varied in body size and nesting preference. We aimed to understand effects of landscape fragmentation and bee traits on bee fitness and the pollination services bees provide, as well as interactions between them, and the general consequences it has to our understanding of the system. This broad scope gives multiple key results. 1) Body size determines fitness more than landscape fragmentation, with large bees building fewer brood cells. High pollen requirements for large bees and the related high time budgets for visiting many flowers may not compensate for faster flight speeds and short handling times on flowers, giving them overall a disadvantage compared to small bees. 2) Nest preference does affect distribution of bees over the landscape, with cavity-nesting bees being restricted to nesting along field edges, which inevitably leads to performance reductions. Fragmentation mitigates this for cavity-nesting bees through increased edge habitat. 3) Landscape fragmentation alone had a relatively small effect on all responses. Instead, the local ratio of nest to foraging habitat affected bee fitness positively through reduced local competition. The spatial coverage of pollination increases steeply in response to this ratio for all bee sizes. The nest to foraging habitat ratio, a strong habitat proxy incorporating fragmentation could be a promising and practical measure for comparing landscape suitability for pollinators. 4) The number of flower visits was hardly affected by resource allocation, but predominantly by bee size. 5) In landscapes with the highest visitation coverage, bees flew least far, suggesting that these pollination proxies are subject to a trade-off between either longer pollen transport distances or a better pollination coverage, linked to how nests are distributed over the landscape rather than being affected by bee size. PMID:29444076

Fragmentation of nest and foraging habitat affects time budgets of solitary bees, their fitness and pollination services, depending on traits: Results from an individual-based model.

PubMed

Everaars, Jeroen; Settele, Josef; Dormann, Carsten F

2018-01-01

Solitary bees are important but declining wild pollinators. During daily foraging in agricultural landscapes, they encounter a mosaic of patches with nest and foraging habitat and unsuitable matrix. It is insufficiently clear how spatial allocation of nesting and foraging resources and foraging traits of bees affect their daily foraging performance. We investigated potential brood cell construction (as proxy of fitness), number of visited flowers, foraging habitat visitation and foraging distance (pollination proxies) with the model SOLBEE (simulating pollen transport by solitary bees, tested and validated in an earlier study), for landscapes varying in landscape fragmentation and spatial allocation of nesting and foraging resources. Simulated bees varied in body size and nesting preference. We aimed to understand effects of landscape fragmentation and bee traits on bee fitness and the pollination services bees provide, as well as interactions between them, and the general consequences it has to our understanding of the system. This broad scope gives multiple key results. 1) Body size determines fitness more than landscape fragmentation, with large bees building fewer brood cells. High pollen requirements for large bees and the related high time budgets for visiting many flowers may not compensate for faster flight speeds and short handling times on flowers, giving them overall a disadvantage compared to small bees. 2) Nest preference does affect distribution of bees over the landscape, with cavity-nesting bees being restricted to nesting along field edges, which inevitably leads to performance reductions. Fragmentation mitigates this for cavity-nesting bees through increased edge habitat. 3) Landscape fragmentation alone had a relatively small effect on all responses. Instead, the local ratio of nest to foraging habitat affected bee fitness positively through reduced local competition. The spatial coverage of pollination increases steeply in response to this ratio for all bee sizes. The nest to foraging habitat ratio, a strong habitat proxy incorporating fragmentation could be a promising and practical measure for comparing landscape suitability for pollinators. 4) The number of flower visits was hardly affected by resource allocation, but predominantly by bee size. 5) In landscapes with the highest visitation coverage, bees flew least far, suggesting that these pollination proxies are subject to a trade-off between either longer pollen transport distances or a better pollination coverage, linked to how nests are distributed over the landscape rather than being affected by bee size.

Nutrient-mediated architectural plasticity of a predatory trap.

PubMed

Blamires, Sean J; Tso, I-Min

2013-01-01

Nutrients such as protein may be actively sought by foraging animals. Many predators exhibit foraging plasticity, but how their foraging strategies are affected when faced with nutrient deprivation is largely unknown. In spiders, the assimilation of protein into silk may be in conflict with somatic processes so we predicted web building to be affected under protein depletion. To assess the influence of protein intake on foraging plasticity we fed the orb-web spiders Argiope aemula and Cyclosa mulmeinensis high, low or no protein solutions over 10 days and allowed them to build webs. We compared post-feeding web architectural components and major ampullate (MA) silk amino acid compositions. We found that the number of radii in webs increased in both species when fed high protein solutions. Mesh size increased in A. aemula when fed a high protein solution. MA silk proline and alanine compositions varied in each species with contrasting variations in alanine between the two species. Glycine compositions only varied in C. mulmeinensis silk. No spiders significantly lost or gained mass on any feeding treatment, so they did not sacrifice somatic maintenance for amino acid investment in silk. Our results show that the amount of protein taken in significantly affects the foraging decisions of trap-building predators, such as orb web spiders. Nevertheless, the subtle differences found between species in the association between protein intake, the amino acids invested in silk and web architectural plasticity show that the influence of protein deprivation on specific foraging strategies differs among different spiders.

The influence of oceanographic features on the foraging behavior of the olive ridley sea turtle Lepidochelys olivacea along the Guiana coast

NASA Astrophysics Data System (ADS)

Chambault, Philippine; de Thoisy, Benoît; Heerah, Karine; Conchon, Anna; Barrioz, Sébastien; Dos Reis, Virginie; Berzins, Rachel; Kelle, Laurent; Picard, Baptiste; Roquet, Fabien; Le Maho, Yvon; Chevallier, Damien

2016-03-01

The circulation in the Western Equatorial Atlantic is characterized by a highly dynamic mesoscale activity that shapes the Guiana continental shelf. Olive ridley sea turtles (Lepidochelys olivacea) nesting in French Guiana cross this turbulent environment during their post-nesting migration. We studied how oceanographic and biological conditions drove the foraging behavior of 18 adult females, using satellite telemetry, remote sensing data (sea surface temperature, sea surface height, current velocity and euphotic depth), simulations of micronekton biomass (pelagic organisms) and in situ records (water temperature and salinity). The occurrence of foraging events throughout migration was located using Residence Time analysis, while an innovative proxy of the hunting time within a dive was used to identify and quantify foraging events during dives. Olive ridleys migrated northwestwards using the Guiana current and remained on the continental shelf at the edge of eddies formed by the North Brazil retroflection, an area characterized by low turbulence and high micronekton biomass. They performed mainly pelagic dives, hunting for an average 77% of their time. Hunting time within a dive increased with shallower euphotic depth and with lower water temperatures, and mean hunting depth increased with deeper thermocline. This is the first study to quantify foraging activity within dives in olive ridleys, and reveals the crucial role played by the thermocline on the foraging behavior of this carnivorous species. This study also provides novel and detailed data describing how turtles actively use oceanographic structures during post-nesting migration.

Implementing the expanded prescribed fire program on the Gila National Forest, New Mexico: implications for snag management

Treesearch

Paul F. Boucher; William M. Block; Gary V. Benavidez; L. E. Wiebe

2000-01-01

Efforts to return natural fire to the Gila National Forest, New Mexico, have resulted in controversy regarding management of snags (standing dead trees). The importance of snags for wildlife, especially cavity-dependent birds, is well documented. Although general uses of snags by birds are known (nesting, roosting, perching, and foraging), we know little about the...

Modeling of Habitat and Foraging Behavior of Beaked Whales in the Southern California Bight

DTIC Science & Technology

2014-09-30

preference. APPROACH High-Frequency Acoustic Recording Packages ( HARPs , Wiggins & Hildebrand 2007) have collected acoustic data at 17 sites...signal processing for HARP data is performed using the MATLAB (Mathworks, Natick, MA) based custom program Triton (Wiggins & Hildebrand 2007) and... HARP data are stored with the remainder of metadata (e.g. project name, instrument location, detection settings, detection effort) in the database

The forager oral tradition and the evolution of prolonged juvenility.

PubMed

Scalise Sugiyama, Michelle

2011-01-01

The foraging niche is characterized by the exploitation of nutrient-rich resources using complex extraction techniques that take a long time to acquire. This costly period of development is supported by intensive parental investment. Although human life history theory tends to characterize this investment in terms of food and care, ethnographic research on foraging skill transmission suggests that the flow of resources from old-to-young also includes knowledge. Given the adaptive value of information, parents may have been under selection pressure to invest knowledge - e.g., warnings, advice - in children: proactive provisioning of reliable information would have increased offspring survival rates and, hence, parental fitness. One way that foragers acquire subsistence knowledge is through symbolic communication, including narrative. Tellingly, oral traditions are characterized by an old-to-young transmission pattern, which suggests that, in forager groups, storytelling might be an important means by which adults transfer knowledge to juveniles. In particular, by providing juveniles with vicarious experience, storytelling may expand episodic memory, which is believed to be integral to the generation of possible future scenarios (i.e., planning). In support of this hypothesis, this essay reviews evidence that: mastery of foraging knowledge and skill sets takes a long time to acquire; foraging knowledge is transmitted from parent to child; the human mind contains adaptations specific to social learning; full assembly of learning mechanisms is not complete in early childhood; and forager oral traditions contain a wide range of information integral to occupation of the foraging niche. It concludes with suggestions for tests of the proposed hypothesis.

Flight restriction prevents associative learning deficits but not changes in brain protein-adduct formation during honeybee ageing.

PubMed

Tolfsen, Christina C; Baker, Nicholas; Kreibich, Claus; Amdam, Gro V

2011-04-15

Honeybees (Apis mellifera) senesce within 2 weeks after they discontinue nest tasks in favour of foraging. Foraging involves metabolically demanding flight, which in houseflies (Musca domestica) and fruit flies (Drosophila melanogaster) is associated with markers of ageing such as increased mortality and accumulation of oxidative damage. The role of flight in honeybee ageing is incompletely understood. We assessed relationships between honeybee flight activity and ageing by simulating rain that confined foragers to their colonies most of the day. After 15 days on average, flight-restricted foragers were compared with bees with normal (free) flight: one group that foraged for ∼15 days and two additional control groups, for flight duration and chronological age, that foraged for ∼5 days. Free flight over 15 days on average resulted in impaired associative learning ability. In contrast, flight-restricted foragers did as well in learning as bees that foraged for 5 days on average. This negative effect of flight activity was not influenced by chronological age or gustatory responsiveness, a measure of the bees' motivation to learn. Contrasting their intact learning ability, flight-restricted bees accrued the most oxidative brain damage as indicated by malondialdehyde protein adduct levels in crude cytosolic fractions. Concentrations of mono- and poly-ubiquitinated brain proteins were equal between the groups, whereas differences in total protein amounts suggested changes in brain protein metabolism connected to forager age, but not flight. We propose that intense flight is causal to brain deficits in aged bees, and that oxidative protein damage is unlikely to be the underlying mechanism.

Flight restriction prevents associative learning deficits but not changes in brain protein-adduct formation during honeybee ageing

PubMed Central

Tolfsen, Christina C.; Baker, Nicholas; Kreibich, Claus; Amdam, Gro V.

2011-01-01

SUMMARY Honeybees (Apis mellifera) senesce within 2 weeks after they discontinue nest tasks in favour of foraging. Foraging involves metabolically demanding flight, which in houseflies (Musca domestica) and fruit flies (Drosophila melanogaster) is associated with markers of ageing such as increased mortality and accumulation of oxidative damage. The role of flight in honeybee ageing is incompletely understood. We assessed relationships between honeybee flight activity and ageing by simulating rain that confined foragers to their colonies most of the day. After 15 days on average, flight-restricted foragers were compared with bees with normal (free) flight: one group that foraged for ∼15 days and two additional control groups, for flight duration and chronological age, that foraged for ∼5 days. Free flight over 15 days on average resulted in impaired associative learning ability. In contrast, flight-restricted foragers did as well in learning as bees that foraged for 5 days on average. This negative effect of flight activity was not influenced by chronological age or gustatory responsiveness, a measure of the bees' motivation to learn. Contrasting their intact learning ability, flight-restricted bees accrued the most oxidative brain damage as indicated by malondialdehyde protein adduct levels in crude cytosolic fractions. Concentrations of mono- and poly-ubiquitinated brain proteins were equal between the groups, whereas differences in total protein amounts suggested changes in brain protein metabolism connected to forager age, but not flight. We propose that intense flight is causal to brain deficits in aged bees, and that oxidative protein damage is unlikely to be the underlying mechanism. PMID:21430210

The Forager Oral Tradition and the Evolution of Prolonged Juvenility

PubMed Central

Scalise Sugiyama, Michelle

2011-01-01

The foraging niche is characterized by the exploitation of nutrient-rich resources using complex extraction techniques that take a long time to acquire. This costly period of development is supported by intensive parental investment. Although human life history theory tends to characterize this investment in terms of food and care, ethnographic research on foraging skill transmission suggests that the flow of resources from old-to-young also includes knowledge. Given the adaptive value of information, parents may have been under selection pressure to invest knowledge – e.g., warnings, advice – in children: proactive provisioning of reliable information would have increased offspring survival rates and, hence, parental fitness. One way that foragers acquire subsistence knowledge is through symbolic communication, including narrative. Tellingly, oral traditions are characterized by an old-to-young transmission pattern, which suggests that, in forager groups, storytelling might be an important means by which adults transfer knowledge to juveniles. In particular, by providing juveniles with vicarious experience, storytelling may expand episodic memory, which is believed to be integral to the generation of possible future scenarios (i.e., planning). In support of this hypothesis, this essay reviews evidence that: mastery of foraging knowledge and skill sets takes a long time to acquire; foraging knowledge is transmitted from parent to child; the human mind contains adaptations specific to social learning; full assembly of learning mechanisms is not complete in early childhood; and forager oral traditions contain a wide range of information integral to occupation of the foraging niche. It concludes with suggestions for tests of the proposed hypothesis. PMID:21897825

Extreme precipitation variability, forage quality and large herbivore diet selection in arid environments

USGS Publications Warehouse

Cain, James W.; Gedir, Jay V.; Marshal, Jason P.; Krausman, Paul R.; Allen, Jamison D.; Duff, Glenn C.; Jansen, Brian; Morgart, John R.

2017-01-01

Nutritional ecology forms the interface between environmental variability and large herbivore behaviour, life history characteristics, and population dynamics. Forage conditions in arid and semi-arid regions are driven by unpredictable spatial and temporal patterns in rainfall. Diet selection by herbivores should be directed towards overcoming the most pressing nutritional limitation (i.e. energy, protein [nitrogen, N], moisture) within the constraints imposed by temporal and spatial variability in forage conditions. We investigated the influence of precipitation-induced shifts in forage nutritional quality and subsequent large herbivore responses across widely varying precipitation conditions in an arid environment. Specifically, we assessed seasonal changes in diet breadth and forage selection of adult female desert bighorn sheep Ovis canadensis mexicana in relation to potential nutritional limitations in forage N, moisture and energy content (as proxied by dry matter digestibility, DMD). Succulents were consistently high in moisture but low in N and grasses were low in N and moisture until the wet period. Nitrogen and moisture content of shrubs and forbs varied among seasons and climatic periods, whereas trees had consistently high N and moderate moisture levels. Shrubs, trees and succulents composed most of the seasonal sheep diets but had little variation in DMD. Across all seasons during drought and during summer with average precipitation, forages selected by sheep were higher in N and moisture than that of available forage. Differences in DMD between sheep diets and available forage were minor. Diet breadth was lowest during drought and increased with precipitation, reflecting a reliance on few key forage species during drought. Overall, forage selection was more strongly associated with N and moisture content than energy content. Our study demonstrates that unlike north-temperate ungulates which are generally reported to be energy-limited, N and moisture may be more nutritionally limiting for desert ungulates than digestible energy.

Good Days, Bad Days: Wind as a Driver of Foraging Success in a Flightless Seabird, the Southern Rockhopper Penguin

PubMed Central

Dehnhard, Nina; Ludynia, Katrin; Poisbleau, Maud; Demongin, Laurent; Quillfeldt, Petra

2013-01-01

Due to their restricted foraging range, flightless seabirds are ideal models to study the short-term variability in foraging success in response to environmentally driven food availability. Wind can be a driver of upwelling and food abundance in marine ecosystems such as the Southern Ocean, where wind regime changes due to global warming may have important ecological consequences. Southern rockhopper penguins (Eudyptes chrysocome) have undergone a dramatic population decline in the past decades, potentially due to changing environmental conditions. We used a weighbridge system to record daily foraging mass gain (the difference in mean mass of adults leaving the colony in the morning and returning to the colony in the evening) of adult penguins during the chick rearing in two breeding seasons. We related the day-to-day variability in foraging mass gain to ocean wind conditions (wind direction and wind speed) and tested for a relationship between wind speed and sea surface temperature anomaly (SSTA). Foraging mass gain was highly variable among days, but did not differ between breeding seasons, chick rearing stages (guard and crèche) and sexes. It was strongly correlated between males and females, indicating synchronous changes among days. There was a significant interaction of wind direction and wind speed on daily foraging mass gain. Foraging mass gain was highest under moderate to strong winds from westerly directions and under weak winds from easterly directions, while decreasing under stronger easterly winds and storm conditions. Ocean wind speed showed a negative correlation with daily SSTA, suggesting that winds particularly from westerly directions might enhance upwelling and consequently the prey availability in the penguins' foraging areas. Our data emphasize the importance of small-scale, wind-induced patterns in prey availability on foraging success, a widely neglected aspect in seabird foraging studies, which might become more important with increasing changes in climatic variability. PMID:24236139

Nutritional composition and in vitro digestibility of grass and legume winter (cover) crops.

PubMed

Brown, A N; Ferreira, G; Teets, C L; Thomason, W E; Teutsch, C D

2018-03-01

In dairy farming systems, growing winter crops for forage is frequently limited to annual grasses grown in monoculture. The objectives of this study were to determine how cropping grasses alone or in mixtures with legumes affects the yield, nutritional composition, and in vitro digestibility of fresh and ensiled winter crops and the yield, nutritional composition, and in vitro digestibility of the subsequent summer crops. Experimental plots were planted with 15 different winter crops at 3 locations in Virginia. At each site, 4 plots of each treatment were planted in a randomized complete block design. The 15 treatments included 5 winter annual grasses [barley (BA), ryegrass (RG), rye (RY), triticale (TR), and wheat (WT)] in monoculture [i.e., no legumes (NO)] or with 1 of 2 winter annual legumes [crimson clover (CC) and hairy vetch (HV)]. After harvesting the winter crops, corn and forage sorghum were planted within the same plots perpendicular to the winter crop plantings. The nutritional composition and the in vitro digestibility of winter and summer crops were determined for fresh and ensiled samples. Growing grasses in mixtures with CC increased forage dry matter (DM) yield (2.84 Mg/ha), but the yield of mixtures with HV (2.47 Mg/ha) was similar to that of grasses grown in monoculture (2.40 Mg/ha). Growing grasses in mixtures with legumes increased the crude protein concentration of the fresh forage from 13.0% to 15.5% for CC and to 17.3% for HV. For neutral detergent fiber (NDF) concentrations, the interaction between grasses and legumes was significant for both fresh and ensiled forages. Growing BA, RY, and TR in mixtures with legumes decreased NDF concentrations, whereas growing RG and WT with legumes did not affect the NDF concentrations of either the fresh or the ensiled forages. Growing grasses in mixtures with legumes decreased the concentration of sugars of fresh forages relative to grasses grown in monoculture. Primarily, this decrease can be attributed to low concentrations of sugars of mixtures with HV (10.5%). Growing grasses in mixtures with legumes reduced the fiber digestibility of both winter crops (75.7% to 72.8% NDF). Growing grasses in mixtures with legumes did not affect estimated DM yield, nutritional composition, or digestibility of the succeeding summer crops. In conclusion, growing grasses in mixtures with legumes as winter forage crops can increase forage estimated DM yields and its nutritional quality in dairy farming sytems. Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Bigger is better: honeybee colonies as distributed information-gathering systems.

PubMed

Donaldson-Matasci, Matina C; DeGrandi-Hoffman, Gloria; Dornhaus, Anna

2013-03-01

In collectively foraging groups, communication about food resources can play an important role in the organization of the group's activity. For example, the honeybee dance communication system allows colonies to selectively allocate foragers among different floral resources according to their quality. Because larger groups can potentially collect more information than smaller groups, they might benefit more from communication because it allows them to integrate and use that information to coordinate forager activity. Larger groups might also benefit more from communication because it allows them to dominate high-value resources by recruiting large numbers of foragers. By manipulating both colony size and the ability to communicate location information in the dance, we show that larger colonies of honeybees benefit more from communication than do smaller colonies. In fact, colony size and dance communication worked together to improve foraging performance; the estimated net gain per foraging trip was highest in larger colonies with unimpaired communication. These colonies also had the earliest peaks in foraging activity, but not the highest ones. This suggests they may find and recruit to resources more quickly, but not more heavily. The benefits of communication we observed in larger colonies are thus likely a result of more effective informationgathering due to massive parallel search rather than increased competitive ability due to heavy recruitment.

Foraging decisions, patch use, and seasonality in egrets (Aves: ciconiiformes)

USGS Publications Warehouse

Erwin, R.M.

1985-01-01

Feeding snowy (Egretta thula) and great (Casmerodius albus) egrets were observed during 2 breeding seasons in coastal New Jersey and 2 brief winter periods in northeast Florida (USA). A number of tests based on assumptions of foraging models, predictions from foraging theory, and earlier empirical tests concerning time allocation and movement in foraging patches was made. Few of the expectations based on foraging theory and/or assumptions were supported by the empirical evidence. Snowy egrets fed with greater intensity and efficiency during the breeding season (when young were being fed) than during winter. They also showed some tendency to leave patches when their capture rate declined, and they spent more time foraging in patches when other birds were present nearby. Great egrets showed few of these tendencies, although they did leave patches when their intercapture intervals increased. Satiation differences had some influence on feeding rates in snowy egrets, but only at the end of feeding bouts. Some individuals of both species revisited areas in patches that had recently been exploited, and success rates were usually higher after the 2nd visit. Apparently, for predators of active prey, short-term changes in resource availability ('resource depression') may be more important than resource depletion, a common assumption in most optimal foraging theory models.

Bigger is better: honeybee colonies as distributed information-gathering systems

PubMed Central

Donaldson-Matasci, Matina C.; DeGrandi-Hoffman, Gloria; Dornhaus, Anna

2015-01-01

In collectively foraging groups, communication about food resources can play an important role in the organization of the group’s activity. For example, the honeybee dance communication system allows colonies to selectively allocate foragers among different floral resources according to their quality. Because larger groups can potentially collect more information than smaller groups, they might benefit more from communication because it allows them to integrate and use that information to coordinate forager activity. Larger groups might also benefit more from communication because it allows them to dominate high-value resources by recruiting large numbers of foragers. By manipulating both colony size and the ability to communicate location information in the dance, we show that larger colonies of honeybees benefit more from communication than do smaller colonies. In fact, colony size and dance communication worked together to improve foraging performance; the estimated net gain per foraging trip was highest in larger colonies with unimpaired communication. These colonies also had the earliest peaks in foraging activity, but not the highest ones. This suggests they may find and recruit to resources more quickly, but not more heavily. The benefits of communication we observed in larger colonies are thus likely a result of more effective informationgathering due to massive parallel search rather than increased competitive ability due to heavy recruitment. PMID:26213412

Space use and resource selection by foraging Indiana bats at the northern edge of their distribution

USGS Publications Warehouse

Jachowski, David S.; Johnson, Joshua B.; Dobony, Christopher A.; Edwards, John W.; Ford, W. Mark

2014-01-01

Despite 4 decades of conservation concern, managing endangered Indiana bat (Myotis sodalis) populations remains a difficult wildlife resource issue facing natural resource managers in the eastern United States. After small signs of population recovery, the recent emergence of white-nose syndrome has led to concerns of local and/or regional extirpation of the species. Where Indiana bats persist, retaining high-quality foraging areas will be critical to meet physiological needs and ensure successful recruitment and overwinter survival. However, insight into foraging behavior has been lacking in the Northeast of the USA. We radio-tracked 12 Indiana bats over 2 summers at Fort Drum, New York, to evaluate factors influencing Indiana bat resource selection during night-time foraging. We found that foraging space use decreased 2% for every 100 m increase in distance to water and 6% for every 100 m away from the forest edge. This suggests high use of riparian areas in close proximity to forest and is somewhat consistent with the species’ foraging ecology in the Midwest and upper South. Given the importance of providing access to high-quality foraging areas during the summer maternity season, Indiana bat conservation at the northern extent of the species’ range will be linked to retention of forested habitat in close proximity to riparian zones. 

Dissecting the genetics of rhizomatousness: Towards sustainable food, forage, and bioenergy

USDA-ARS?s Scientific Manuscript database

Rhizomatousness is a key trait influencing both the perenniality and biomass partitioning of plants. Increased understanding of the genetic control of rhizome growth offers potential towards the creation of more sustainable grain, forage, and bioenergy cropping systems. It is also applicable to th...

Genomic selection in forage breeding: designing an estimation population

USDA-ARS?s Scientific Manuscript database

The benefits of genomic selection to livestock, crops and forest tree breeding can be extended to forage grasses and legumes. The main benefits expected are increased selection accuracy and reduced costs per unit of genotype evaluated and breeding cycle length. Aiming at designing a training populat...

Mob grazing for dairy cows

USDA-ARS?s Scientific Manuscript database

Proponents of mob grazing emphasize increased forage use efficiency and soil improvement by grazing mature forage with stocking densities up to 560,425 lb/ac of beef cattle on small paddocks with rest periods up to 125 days. However, it is unclear if this management technique is appropriate for dair...

Increase in dance imprecision with decreasing foraging distance in the honey bee Apis mellifera L. is partly explained by physical constraints.

PubMed

Beekman, Madeleine; Doyen, Laurent; Oldroyd, Benjamin P

2005-12-01

Honey bee foragers communicate the direction and distance of both food sources and new nest sites to nest mates by means of a symbolic dance language. Interestingly, the precision by which dancers transfer directional information is negatively correlated with the distance to the advertised food source. The 'tuned-error' hypothesis suggests that colonies benefit from this imprecision as it spreads recruits out over a patch of constant size irrespective of the distance to the advertised site. An alternative to the tuned-error hypothesis is that dancers are physically incapable of dancing with great precision for nearby sources. Here we revisit the tuned-error hypothesis by studying the change in dance precision with increasing foraging distance over relatively short distances while controlling for environmental influences. We show that bees indeed increase their dance precision with the increase in foraging distance. However, we also show that dance performed by swarm-scouts for a nearby (30 m) nest site, where there could be no benefit to imprecision, are either without or with only limited directional information. This result suggests that imprecision in dance communication is caused primarily by physical constraints in the ability of dancers to turn around quickly enough when the advertised site is nearby.

Assignment tests, telemetry and tag-recapture data converge to identify natal origins of leatherback turtles foraging in Atlantic Canadian waters.

PubMed

Stewart, Kelly R; James, Michael C; Roden, Suzanne; Dutton, Peter H

2013-07-01

Investigating migratory connectivity between breeding and foraging areas is critical to effective management and conservation of highly mobile marine taxa, particularly threatened, endangered, or economically important species that cross through regional, national and international boundaries. The leatherback turtle (Dermochelys coriacea, Vandelli 1761) is one such transboundary species that spends time at breeding areas at low latitudes in the northwest Atlantic during spring and summer. From there, they migrate widely throughout the North Atlantic, but many show fidelity to one region off eastern Canada, where critical foraging habitat has been proposed. Our goal was to identify nesting beach origins for turtles foraging here. Using genetics, we identified natal beaches for 288 turtles that were live-captured off the coast of Nova Scotia, Canada. Turtles were sampled (skin or blood) and genotyped using 17 polymorphic microsatellite markers. Results from three assignment testing programs (ONCOR, GeneClass2 and Structure) were compared. Our nesting population reference data set included 1417 individuals from nine Atlantic nesting assemblages. A supplementary data set for 83 foraging turtles traced to nesting beaches using flipper tags and/or PIT tags (n = 72), or inferred from satellite telemetry (n = 11), enabled ground-truthing of the assignments. We first assigned turtles using only genetic information and then used the supplementary recapture information to verify assignments. ONCOR performed best, assigning 64 of the 83 recaptured turtles to natal beaches (77·1%). Turtles assigned to Trinidad (164), French Guiana (72), Costa Rica (44), St. Croix (7), and Florida (1) reflect the relative size of those nesting populations, although none of the turtles were assigned to four other potential source nesting assemblages. Our results demonstrate the utility of genetic approaches for determining source populations of foraging marine animals and include the first identification of natal rookeries of male leatherbacks, identified through satellite telemetry and verified with genetics. This work highlights the importance of long-term monitoring and tagging programmes in nesting and high-use foraging areas. Moreover, it provides a scientific basis for evaluating stock-specific effects of fisheries on migratory marine species, thus identifying where coordinated international recovery efforts may be most effective. © 2013 NOAA ‐ National Marine Fisheries Service. Journal of Animal Ecology © 2013 British Ecological Society.

Giant panda foraging and movement patterns in response to bamboo shoot growth.

PubMed

Zhang, Mingchun; Zhang, Zhizhong; Li, Zhong; Hong, Mingsheng; Zhou, Xiaoping; Zhou, Shiqiang; Zhang, Jindong; Hull, Vanessa; Huang, Jinyan; Zhang, Hemin

2018-03-01

Diet plays a pivotal role in dictating behavioral patterns of herbivorous animals, particularly specialist species. The giant panda (Ailuropoda melanoleuca) is well-known as a bamboo specialist. In the present study, the response of giant pandas to spatiotemporal variation of bamboo shoots was explored using field surveys and GPS collar tracking. Results show the dynamics in panda-bamboo space-time relationships that have not been previously articulated. For instance, we found a higher bamboo stump height of foraged bamboo with increasing elevation, places where pandas foraged later in spring when bamboo shoots become more fibrous and woody. The time required for shoots to reach optimum height for foraging was significantly delayed as elevation increased, a pattern which corresponded with panda elevational migration patterns beginning from the lower elevational end of Fargesia robusta distribution and gradually shifting upward until the end of the shooting season. These results indicate that giant pandas can respond to spatiotemporal variation of bamboo resources, such as available shoots. Anthropogenic interference of low-elevation F. robusta habitat should be mitigated, and conservation attention and increased monitoring should be given to F. robusta areas at the low- and mid-elevation ranges, particularly in the spring shooting season.

Baseline glucose level is an individual trait that is negatively associated with lifespan and increases due to adverse environmental conditions during development and adulthood.

PubMed

Montoya, Bibiana; Briga, Michael; Jimeno, Blanca; Moonen, Sander; Verhulst, Simon

2018-05-01

High baseline glucose levels are associated with pathologies and shorter lifespan in humans, but little is known about causes and consequences of individual variation in glucose levels in other species. We tested to what extent baseline blood glucose level is a repeatable trait in adult zebra finches, and whether glucose levels were associated with age, manipulated environmental conditions during development (rearing brood size) and adulthood (foraging cost), and lifespan. We found that: (1) repeatability of glucose levels was 30%, both within and between years. (2) Having been reared in a large brood and living with higher foraging costs as adult were independently associated with higher glucose levels. Furthermore, the finding that baseline glucose was low when ambient temperature was high, and foraging costs were low, indicates that glucose is regulated at a lower level when energy turnover is low. (3) Survival probability decreased with increasing baseline glucose. We conclude that baseline glucose is an individual trait negatively associated with survival, and increases due to adverse environmental conditions during development (rearing brood size) and adulthood (foraging cost). Blood glucose may be, therefore, part of the physiological processes linking environmental conditions to lifespan.

Comparison of alternative beef production systems based on forage finishing or grain-forage diets with or without growth promotants: 1. Feedlot performance, carcass quality, and production costs.

PubMed

Berthiaume, R; Mandell, I; Faucitano, L; Lafrenière, C

2006-08-01

Forty Angus-cross steers were used to evaluate 5 beef cattle management regimens for their effect on growth performance, carcass characteristics, and cost of production. A 98-d growing phase was incorporated using grass silage with or without growth promotants (trenbolone acetate + estradiol implants, and monensin in the feed) or soybean meal. Dietary treatments in the finishing phase were developed, with or without addition of the same growth promotants, based on exclusive feeding of forages with minimal supplementation or the feeding of barley-based diets. Overall, ADG for animals treated with growth promotants or fed supplemented diets (soybean meal and barley) was increased (P < 0.01) by 25 and 21%, respectively, compared with steers reared on grass silage alone and not treated with growth promotants. Except for HCW (P < 0.01), the use of growth promotants did not affect carcass measurements. Increasing the proportion of barley in the diet of steers finished on forage produced a heavier HCW (P < 0.01) and a greater (P < 0.01) quality grade. Because of their lower HCW and quality grade, cattle targeted to a forage-fed, nonimplanted beef market would need to garner a 16% premium to be economically competitive with cattle finished conventionally.

Parasitoid Diaeretiella rapae (Hymenoptera: Braconidae) Adjusts Reproductive Strategy When Competing for Hosts.

PubMed

Kant, Rashmi; Minor, Maria A

2017-06-01

Parasitoid fitness depends on its ability to manipulate reproductive strategies when in competition. This study investigated the parasitism and sex allocation strategies of the parasitic wasp Diaeretiella rapae McIntosh at a range of host (Brevicoryne brassicae L.) and conspecific densities. The results suggest that D. rapae females adjust their progeny production and progeny sex ratio with changing competition. When foraging alone, female D. rapae parasitize larger number of B. brassicae nymphs when the number of available hosts is increased, but the overall proportion of parasitized hosts decreases with increase in host density. The proportion of female offspring also decreases with elevated host density. Increase in the number of female D. rapae foraging together increased total parasitism, but reduced relative contribution of each individual female. The number of female progeny decreased when multiple females competed for the same host. However, foraging experience in the presence of one or more conspecifics increased the parasitism rate and proportion of female progeny. Competing females were more active during oviposition and had shorter lives. The study suggests that both host and foundress (female parasitoid) densities have significant effect on progeny production, sex allocation, and longevity of foraging females. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Amygdala Signaling during Foraging in a Hazardous Environment.

PubMed

Amir, Alon; Lee, Seung-Chan; Headley, Drew B; Herzallah, Mohammad M; Pare, Denis

2015-09-23

We recorded basolateral amygdala (BL) neurons in a seminaturalistic foraging task. Rats had to leave their nest to retrieve food in an elongated arena inhabited by a mechanical predator. There were marked trial-to-trial variations in behavior. After poking their head into the foraging arena and waiting there for a while, rats either retreated to their nest or initiated foraging. Before initiating foraging, rats waited longer on trials that followed failed than successful trials indicating that prior experience influenced behavior. Upon foraging initiation, most principal cells (Type-1) reduced their firing rate, while in a minority (Type-2) it increased. When rats aborted foraging, Type-1 cells increased their firing rates, whereas in Type-2 cells it did not change. Surprisingly, the opposite activity profiles of Type-1 and Type-2 units were also seen in control tasks devoid of explicit threats or rewards. The common correlate of BL activity across these tasks was movement velocity, although an influence of position was also observed. Thus depending on whether rats initiated movement or not, the activity of BL neurons decreased or increased, regardless of whether threat or rewards were present. Therefore, BL activity not only encodes threats or rewards, but is closely related to behavioral output. We propose that higher order cortical areas determine task-related changes in BL activity as a function of reward/threat expectations and internal states. Because Type-1 and Type-2 cells likely form differential connections with the central amygdala (controlling freezing), this process would determine whether movement aimed at attaining food or exploration is suppressed or facilitated. Significance statement: For decades, amygdala research has been dominated by pavlovian and operant conditioning paradigms. This work has led to the view that amygdala neurons signal threats or rewards, in turn causing defensive or approach behaviors. However, the artificial circumstances of conditioning studies bear little resemblance to normal life. In natural conditions, subjects are simultaneously presented with potential threats and rewards, forcing them to engage in a form of risk assessment. We examined this process using a seminaturalistic foraging task. In constant conditions of threats and rewards, amygdala activity could be high or low, depending on the rats' decisions on a given trial. Therefore, amygdala activity does not only encode threats or rewards but is also closely related to behavioral output. Copyright © 2015 the authors 0270-6474/15/3512994-12$15.00/0.

Precision-feeding dairy heifers a high rumen-degradable protein diet with different proportions of dietary fiber and forage-to-concentrate ratios.

PubMed

Lascano, G J; Koch, L E; Heinrichs, A J

2016-09-01

The objective of this experiment was to determine the effects of feeding a high-rumen-degradable protein (RDP) diet when dietary fiber content is manipulated within differing forage-to-concentrate ratio (F:C) on nutrient utilization of precision-fed dairy heifers. Six cannulated Holstein heifers (486.98±15.07kg of body weight) were randomly assigned to 2 F:C, low- (45% forage; LF) and high-forage (90% forage; HF) diets and to a fiber proportion sequence [33% grass hay and wheat straw (HS), 67% corn silage (CS; low fiber); 50% HS, 50% CS (medium fiber); and 67% HS, 33% CS (high fiber)] within forage proportion administered according to a split-plot, 3×3 Latin square design (16-d periods). Heifers fed LF had greater apparent total-tract organic matter digestibility coefficients (dC), neutral detergent fiber, and cellulose than those fed LC diets. Substituting CS with HS resulted in a linear reduction in dry matter, organic matter, and cellulose dC. Nitrogen dC was not different between F:C or with increasing proportions of HS in diets, but N retention tended to decrease linearly as HS was increased in the diets. Predicted microbial protein flow to the duodenum decreased linearly with HS addition and protozoa numbers HS interacted linearly, exhibiting a decrease as HS increased for LF, whereas no effects were observed for HF. Blood urea N increased linearly as HS was incorporated. The LF-fed heifers had a greater ruminal volatile fatty acids concentration. We noted a tendency for a greater dry matter, and a significantly higher liquid fraction turnover rate for HF diets. There was a linear numerical increase in the liquid and solid fraction turnover rate as fiber was added to the diets. Rumen fermentation parameters and fractional passages (solid and liquid) rates support the reduction in dC, N retention, and microbial protein synthesis observed as more dietary fiber is added to the rations of dairy heifers precision-fed a constant proportion of rumen-degradable protein. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Persistent producer-scrounger relationships in bats.

PubMed

Harten, Lee; Matalon, Yasmin; Galli, Naama; Navon, Hagit; Dor, Roi; Yovel, Yossi

2018-02-01

Social foraging theory suggests that group-living animals gain from persistent social bonds, which lead to increased tolerance in competitive foraging and information sharing. Bats are among the most social mammals, often living in colonies of tens to thousands of individuals for dozens of years, yet little is known about their social foraging dynamics. We observed three captive bat colonies for over a year, quantifying >13,000 social foraging interactions. We found that individuals consistently used one of two foraging strategies, either producing (collecting) food themselves or scrounging it directly from the mouth of other individuals. Individual foraging types were consistent over at least 16 months except during the lactation period when females shifted toward producing. Scroungers intentionally selected whom to interact with when socially foraging, thus generating persistent nonrandom social relationships with two to three specific producers. These persistent producer-scrounger relationships seem to reduce aggression over time. Finally, scrounging was highly correlated with vigilance, and we hypothesize that vigilant-prone individuals turn to scrounging in the wild to mitigate the risk of landing on a potentially unsafe fruit tree. We find the bat colony to be a rich and dynamic social system, which can serve as a model to study the role that social foraging plays in the evolution of mammalian sociality. Our results highlight the importance of considering individual tendencies when exploring social behavior patterns of group-living animals. These tendencies further emphasize the necessity of studying social networks over time.

Persistent producer-scrounger relationships in bats

PubMed Central

Harten, Lee; Matalon, Yasmin; Galli, Naama; Navon, Hagit; Dor, Roi; Yovel, Yossi

2018-01-01

Social foraging theory suggests that group-living animals gain from persistent social bonds, which lead to increased tolerance in competitive foraging and information sharing. Bats are among the most social mammals, often living in colonies of tens to thousands of individuals for dozens of years, yet little is known about their social foraging dynamics. We observed three captive bat colonies for over a year, quantifying >13,000 social foraging interactions. We found that individuals consistently used one of two foraging strategies, either producing (collecting) food themselves or scrounging it directly from the mouth of other individuals. Individual foraging types were consistent over at least 16 months except during the lactation period when females shifted toward producing. Scroungers intentionally selected whom to interact with when socially foraging, thus generating persistent nonrandom social relationships with two to three specific producers. These persistent producer-scrounger relationships seem to reduce aggression over time. Finally, scrounging was highly correlated with vigilance, and we hypothesize that vigilant-prone individuals turn to scrounging in the wild to mitigate the risk of landing on a potentially unsafe fruit tree. We find the bat colony to be a rich and dynamic social system, which can serve as a model to study the role that social foraging plays in the evolution of mammalian sociality. Our results highlight the importance of considering individual tendencies when exploring social behavior patterns of group-living animals. These tendencies further emphasize the necessity of studying social networks over time. PMID:29441356

Grazing and Land Management Strategies for Hardwood Rangelands

Treesearch

Melvin R. George

1991-01-01

Annual rangelands produce 84 percent of California's range forage which are used all year by sedentary ranching operations and seasonally by migratory operations. Environmental policy, energy and water costs may reduce traditional summer forage sources, resulting in increased grazing pressure on hardwood and annual rangelands. However, the landowner's...

Anthelmintic effect of plant extracts containing condensed and hydrolyzable tannins on Caenorhabditis elegans and their antioxidant capacity

USDA-ARS?s Scientific Manuscript database

Although tannin-rich forages are known to increase protein uptake and to reduce gastrointestinal nematode infections in grazing ruminants, most published research involves forages with condensed tannins (CT), while published literature lacks information on the anthelmintic capacity, nutritional bene...

Methane and hydrogen sulfide production during co-digestion of forage radish and dairy manure

USDA-ARS?s Scientific Manuscript database

Forage radish cover crops were investigated as a co-substrate to increase biogas production from dairy manure-based anaerobic digestion. Lab-scale batch digesters (300 mL) were operated under mesophilic conditions during two experiments. In the first experiment, the optimal co-digestion ratio for ...

Low-dose glyphosate does not control annual bromes in the northern Great Plains

USDA-ARS?s Scientific Manuscript database

Annual bromes (downy brome and Japanese brome) have been shown to decrease perennial grass forage production and alter ecosystem functions in northern Great Plains rangelands. Large-scale chemical control might be a method for increasing rangeland forage production if low application rates confer co...

A look at dairy mob grazing in the Northeast

USDA-ARS?s Scientific Manuscript database

Proponents of ultra-high stocking density (UHSD) grazing emphasize increased forage use efficiency and soil improvement by grazing mature forage with stocking densities up to 560,425 kg/ha of beef cattle on small paddocks with rest periods up to 125 days. However, it is unclear if this management te...

Effects of fire and nitrogen addition on forage quality of Aristida purpurea

USDA-ARS?s Scientific Manuscript database

Purple threeawn (Aristida purpurea Nutt.) is a native perennial bunchgrass with limited forage value that dominates sites with disturbed soils and persists with continued severe grazing. Fire and nitrogen addition have been used to reduce threeawn and may increase grazing utilization of threeawn by...

Composted manure application promotes long-term invasion of semi-arid rangeland by Bromus tectorum

USDA-ARS?s Scientific Manuscript database

Composted organic matter derived from sewage treatment facilities or livestock manure from feedlots is often applied to rangelands of western North America to increase soil fertility, forage production, forage quality, and soil carbon (C) storage. This practice can have a number of undesirable side ...

Evaluation of the nutritional value of locally produced forage in Korea using chemical analysis and in vitro ruminal fermentation.

PubMed

Ki, Kwang Seok; Park, Su Bum; Lim, Dong Hyun; Seo, Seongwon

2017-03-01

The use of locally produced forage (LPF) in cattle production has economic and environmental advantages over imported forage. The objective of this study was to characterize the nutritional value of LPF commonly used in Korea. Differences in ruminal fermentation characteristics were also examined for the LPF species commonly produced from two major production regions: Chungcheong and Jeolla. Ten LPF (five from each of the two regions) and six of the most widely used imported forages originating from North America were obtained at least three times throughout a year. Each forage species was pooled and analyzed for nutrient content using detailed chemical analysis. Ruminal fermentation characteristics were also determined by in vitro anaerobic incubations using strained rumen fluid for 0, 3, 6, 12, 24, and 48 h. At each incubation time, total gas, pH, ammonia, volatile fatty acid (VFA) concentrations, and neutral detergent fiber digestibility were measured. By fitting an exponential model, gas production kinetics were obtained. Significant differences were found in the non-fiber carbohydrate (NFC) content among the forage species and the regions (p<0.01). No nutrient, other than NFC, showed significant differences among the regions. Crude protein, NFC, and acid detergent lignin significantly differed by forage species. The amount of acid detergent insoluble protein tended to differ among the forages. The forages produced in Chungcheong had a higher amount of NFC than that in Jeolla (p<0.05). There were differences in ruminal fermentation of LPF between the two regions and interactions between regions and forage species were also significant (p<0.05). The pH following a 48-h ruminal fermentation was lower in the forages from Chungcheong than from Jeolla (p<0.01), and total VFA concentration was higher in Chungcheong than in Jeolla (p = 0.05). This implies that fermentation was more active with the forages from Chungcheong than from Jeolla. Analysis of gas production profiles showed the rate of fermentation differed among forage species (p<0.05). The results of the present study showed that the nutritional values of some LPF (i.e., corn silage and Italian ryegrass) are comparable to those of imported forages widely used in Korea. This study also indicated that the nutritional value of LPF differs by origin, as well as by forage species. Detailed analyses of nutrient composition and digestion kinetics of LPF should be routinely employed to evaluate the correct nutritional value of LPF and to increase their use in the field.

Evaluation of the nutritional value of locally produced forage in Korea using chemical analysis and in vitro ruminal fermentation

PubMed Central

Ki, Kwang Seok; Park, Su Bum; Lim, Dong Hyun; Seo, Seongwon

2017-01-01

Objective The use of locally produced forage (LPF) in cattle production has economic and environmental advantages over imported forage. The objective of this study was to characterize the nutritional value of LPF commonly used in Korea. Differences in ruminal fermentation characteristics were also examined for the LPF species commonly produced from two major production regions: Chungcheong and Jeolla. Methods Ten LPF (five from each of the two regions) and six of the most widely used imported forages originating from North America were obtained at least three times throughout a year. Each forage species was pooled and analyzed for nutrient content using detailed chemical analysis. Ruminal fermentation characteristics were also determined by in vitro anaerobic incubations using strained rumen fluid for 0, 3, 6, 12, 24, and 48 h. At each incubation time, total gas, pH, ammonia, volatile fatty acid (VFA) concentrations, and neutral detergent fiber digestibility were measured. By fitting an exponential model, gas production kinetics were obtained. Results Significant differences were found in the non-fiber carbohydrate (NFC) content among the forage species and the regions (p<0.01). No nutrient, other than NFC, showed significant differences among the regions. Crude protein, NFC, and acid detergent lignin significantly differed by forage species. The amount of acid detergent insoluble protein tended to differ among the forages. The forages produced in Chungcheong had a higher amount of NFC than that in Jeolla (p<0.05). There were differences in ruminal fermentation of LPF between the two regions and interactions between regions and forage species were also significant (p<0.05). The pH following a 48-h ruminal fermentation was lower in the forages from Chungcheong than from Jeolla (p<0.01), and total VFA concentration was higher in Chungcheong than in Jeolla (p = 0.05). This implies that fermentation was more active with the forages from Chungcheong than from Jeolla. Analysis of gas production profiles showed the rate of fermentation differed among forage species (p<0.05). Conclusion The results of the present study showed that the nutritional values of some LPF (i.e., corn silage and Italian ryegrass) are comparable to those of imported forages widely used in Korea. This study also indicated that the nutritional value of LPF differs by origin, as well as by forage species. Detailed analyses of nutrient composition and digestion kinetics of LPF should be routinely employed to evaluate the correct nutritional value of LPF and to increase their use in the field. PMID:28002936

Geographic structure of adelie penguin populations: overlap in colony-specific foraging areas

USGS Publications Warehouse

Ainley, D.G.; Ribic, C.A.; Ballard, G.; Heath, S.; Gaffney, I.; Karl, B.J.; Barton, K.J.; Wilson, P.R.; Webb, S.

2004-01-01

In an investigation of the factors leading to geographic structuring among Ade??lie Penguin (Pygoscelis adeliae) populations, we studied the size and overlap of colony-specific foraging areas within an isolated cluster of colonies. The study area, in the southwestern Ross Sea, included one large and three smaller colonies, ranging in size from 3900 to 135000 nesting pairs, clustered on Ross and Beaufort Islands. We used triangulation of radio signals from transmitters attached to breeding penguins to determine foraging locations and to define colony-specific foraging areas during the chick-provisioning period of four breeding seasons, 1997-2000. Colony populations (nesting pairs) were determined using aerial photography just after egg-laying; reproductive success was estimated by comparing ground counts of chicks fledged to the number of breeding pairs apparent in aerial photos. Foraging-trip duration, meal size, and adult body mass were estimated using RFID (radio frequency identification) tags and an automated reader and weighbridge. Chick growth was assessed by weekly weighing. We related the following variables to colony size: foraging distance, area, and duration; reproductive success; chick meal size and growth rate; and seasonal variation in adult body mass. We found that penguins foraged closest to their respective colonies, particularly at the smaller colonies. However, as the season progressed, foraging distance, duration, and area increased noticeably, especially at the largest colony. The foraging areas of the smaller colonies overlapped broadly, but very little foraging area overlap existed between the large colony and the smaller colonies, even though the foraging area of the large colony was well within range of the smaller colonies. Instead, the foraging areas of the smaller colonies shifted as that of the large colony grew. Colony size was not related to chick meal size, chick growth, or parental body mass. This differed from the year previous to the study, when foraging trips of the large colony were very long, parents lost mass, and chick meals were smaller. In light of existing data on prey abundance in neritic waters in Antarctica suggesting that krill are relatively evenly distributed and in high abundance in the Southern Ross Sea, we conclude that penguins depleted or changed the availability of their prey, that the degree of alteration was a function of colony size, and that the large colony affected the location (and perhaps ultimately the size) of foraging areas for the smaller colonies. It appears, therefore, that foraging dynamics play a role in the geographic structuring of colonies in this species. ?? 2004 by the Ecological Society of America.

Long-term effects of the 'Exxon Valdez' oil spill: Sea otter foraging in the intertidal as a pathway of exposure to lingering oil

USGS Publications Warehouse

Bodkin, James L.; Ballachey, Brenda E.; Coletti, Heather A.; Esslinger, George G.; Kloecker, Kimberly A.; Rice, Stanley D.; Reed, John; Monson, Daniel H.

2012-01-01

The protracted recovery of some bird and mammal populations in western Prince William Sound (WPWS), Alaska, and the persistence of spilled 'Exxon Valdez' oil in intertidal sediments, suggests a pathway of exposure to consumers that occupy nearshore habitats. To evaluate the hypothesis that sea otter (Enhydra lutris) foraging allows access to lingering oil, we contrast spatial relations between foraging behavior and documented oil distribution. We recovered archival time-depth recorders implanted in 19 sea otters in WPWS, where lingering oil and delayed ecosystem recovery are well documented. Sea otter foraging dives ranged from +2.7 to -92 m below sea level (MLLW), with intertidal accounting for 5 to 38% of all foraging. On average, female sea otters made 16050 intertidal dives per year and 18% of these dives were at depths above the +0.80 m tidal elevation. Males made 4100 intertidal dives per year and 26% of intertidal foraging took place at depths above the +0.80 m tidal elevation. Estimated annual oil encounter rates ranged from 2 to 24 times yr-1 for females, and 2 to 4 times yr-1 for males. Exposure rates increased in spring when intertidal foraging doubled and females were with small pups. In summer 2008, we found sea otter foraging pits on 13.5 of 24.8 km of intertidal shoreline surveyed. Most pits (82%) were within 0.5 m of the zero tidal elevation and 15% were above 0.5 m, the level above which most (65%) lingering oil remains. In August 2008, we detected oil above background concentrations in 18 of 41 (44%) pits excavated by sea otters on beaches with prior evidence of oiling, with total PAH concentrations up to 56000 ng g−1 dry weight. Our estimates of intertidal foraging, the widespread presence of foraging pits in the intertidal, and the presence of oil in and near sea otter foraging pits documents a pathway of exposure from lingering intertidal oil to sea otters foraging in WPWS.

The role of foraging behaviour in the sexual segregation of the African elephant.

PubMed

Shannon, Graeme; Page, Bruce R; Duffy, Kevin J; Slotow, Rob

2006-11-01

Elephants (Loxodonta africana) exhibit pronounced sexual dimorphism, and in this study we test the prediction that the differences in body size and sociality are significant enough to drive divergent foraging strategies and ultimately sexual segregation. Body size influences the foraging behaviour of herbivores through the differential scaling coefficients of metabolism and gut size, with larger bodied individuals being able to tolerate greater quantities of low-quality, fibrous vegetation, whilst having lower mass-specific energy requirements. We test two distinct theories: the scramble competition hypothesis (SCH) and the forage selection hypothesis (FSH). Comprehensive behavioural data were collected from the Pongola Game Reserve and the Phinda Private Game Reserve in South Africa over a 2.5-year period. The data were analysed using sex as the independent variable. Adult females targeted a wider range of species, adopted a more selective foraging approach and exhibited greater bite rates as predicted by the body size hypothesis and the increased demands of reproductive investment (lactation and pregnancy). Males had longer feeding bouts, displayed significantly more destructive behaviour (31% of observations, 11% for females) and ingested greater quantities of forage during each feeding bout. The independent ranging behaviour of adult males enables them to have longer foraging bouts as they experience fewer social constraints than females. The SCH was rejected as a cause of sexual segregation due to the relative abundance of low quality forage, and the fact that feeding heights were similar for both males and females. However, we conclude that the differences in the foraging strategies of the sexes are sufficient to cause spatial segregation as postulated by the FSH. Sexual dimorphism and the associated behavioural differences have important implications for the management and conservation of elephant and other dimorphic species, with the sexes effectively acting as distinct "ecological species".

Evidence for foraging -site fidelity and individual foraging behavior of pelagic cormorants rearing chicks in the gulf of Alaska

USGS Publications Warehouse

Kotzerka, J.; Hatch, Shyla A.; Garthe, S.

2011-01-01

The Pelagic Cormorant (Phalacrocorax pelagicus) is the most widespread cormorant in the North Pacific, but little is known about its foraging and diving behavior. However, knowledge of seabirds' foraging behavior is important to understanding their function in the marine environment. In 2006, using GPS dataloggers, we studied the foraging behavior of 14 male Pelagic Cormorants rearing chicks on Middleton Island, Alaska. For foraging, the birds had high fidelity to a small area 8 km north of the colony. Within that area, the cormorants' diving activity was of two distinct kinds-near-surface dives (1-6 m) and benthic dives (28-33 m). Individuals were consistent in the depths of their dives, either mostly shallow or mostly deep. Few showed no depth preference. Dive duration, time at maximum depth, and pauses at the water surface between consecutive dives were shorter for shallow dives than for deep dives. The cormorants made dives of both types throughout the day, but the frequency of deep dives increased toward evening. Maximum foraging range was 9 km; maximum total distance traveled per trip was 43.4 km. Trip durations ranged from 0.3 to 7.7 hr. Maximum depth of a dive was 42.2 m, and duration of dives ranged from 4 to 120 sec. We found that Pelagic Cormorants at Middleton Island were faithful to one particular foraging area and individuals dived in distinct patterns. Distinct, specialized foraging behavior may be advantageous in reducing intra- and interspecific competition but may also render the species vulnerable to changing environmental conditions. Copyright ?? The Cooper Ornithological Society 2011.

Fatigue modulates dopamine availability and promotes flexible choice reversals during decision making.

PubMed

Iodice, Pierpaolo; Ferrante, Claudio; Brunetti, Luigi; Cabib, Simona; Protasi, Feliciano; Walton, Mark E; Pezzulo, Giovanni

2017-04-03

During decisions, animals balance goal achievement and effort management. Despite physical exercise and fatigue significantly affecting the levels of effort that an animal exerts to obtain a reward, their role in effort-based choice and the underlying neurochemistry are incompletely known. In particular, it is unclear whether fatigue influences decision (cost-benefit) strategies flexibly or only post-decision action execution and learning. To answer this question, we trained mice on a T-maze task in which they chose between a high-cost, high-reward arm (HR), which included a barrier, and a low-cost, low-reward arm (LR), with no barrier. The animals were parametrically fatigued immediately before the behavioural tasks by running on a treadmill. We report a sharp choice reversal, from the HR to LR arm, at 80% of their peak workload (PW), which was temporary and specific, as the mice returned to choose the HC when the animals were successively tested at 60% PW or in a two-barrier task. These rapid reversals are signatures of flexible choice. We also observed increased subcortical dopamine levels in fatigued mice: a marker of individual bias to use model-based control in humans. Our results indicate that fatigue levels can be incorporated in flexible cost-benefits computations that improve foraging efficiency.

Does similarity in call structure or foraging ecology explain interspecific information transfer in wild Myotis bats?

PubMed

Hügel, Theresa; van Meir, Vincent; Muñoz-Meneses, Amanda; Clarin, B-Markus; Siemers, Björn M; Goerlitz, Holger R

2017-01-01

Animals can gain important information by attending to the signals and cues of other animals in their environment, with acoustic information playing a major role in many taxa. Echolocation call sequences of bats contain information about the identity and behaviour of the sender which is perceptible to close-by receivers. Increasing evidence supports the communicative function of echolocation within species, yet data about its role for interspecific information transfer is scarce. Here, we asked which information bats extract from heterospecific echolocation calls during foraging. In three linked playback experiments, we tested in the flight room and field if foraging Myotis bats approached the foraging call sequences of conspecifics and four heterospecifics that were similar in acoustic call structure only (acoustic similarity hypothesis), in foraging ecology only (foraging similarity hypothesis), both, or none. Compared to the natural prey capture rate of 1.3 buzzes per minute of bat activity, our playbacks of foraging sequences with 23-40 buzzes/min simulated foraging patches with significantly higher profitability. In the flight room, M. capaccinii only approached call sequences of conspecifics and of the heterospecific M. daubentonii with similar acoustics and foraging ecology. In the field, M. capaccinii and M. daubentonii only showed a weak positive response to those two species. Our results confirm information transfer across species boundaries and highlight the importance of context on the studied behaviour, but cannot resolve whether information transfer in trawling Myotis is based on acoustic similarity only or on a combination of similarity in acoustics and foraging ecology. Animals transfer information, both voluntarily and inadvertently, and within and across species boundaries. In echolocating bats, acoustic call structure and foraging ecology are linked, making echolocation calls a rich source of information about species identity, ecology and activity of the sender, which receivers might exploit to find profitable foraging grounds. We tested in three lab and field experiments if information transfer occurs between bat species and if bats obtain information about ecology from echolocation calls. Myotis capaccinii/daubentonii bats approached call playbacks, but only those from con- and heterospecifics with similar call structure and foraging ecology, confirming interspecific information transfer. Reactions differed between lab and field, emphasising situation-dependent differences in animal behaviour, the importance of field research, and the need for further studies on the underlying mechanism of information transfer and the relative contributions of acoustic and ecological similarity.

Anthropogenic noise disrupts use of vocal information about predation risk.

PubMed

Kern, Julie M; Radford, Andrew N

2016-11-01

Anthropogenic noise is rapidly becoming a universal environmental feature. While the impacts of such additional noise on avian sexual signals are well documented, our understanding of its effect in other terrestrial taxa, on other vocalisations, and on receivers is more limited. Little is known, for example, about the influence of anthropogenic noise on responses to vocalisations relating to predation risk, despite the potential fitness consequences. We use playback experiments to investigate the impact of traffic noise on the responses of foraging dwarf mongooses (Helogale parvula) to surveillance calls produced by sentinels, individuals scanning for danger from a raised position whose presence usually results in reduced vigilance by foragers. Foragers exhibited a lessened response to surveillance calls in traffic-noise compared to ambient-sound playback, increasing personal vigilance. A second playback experiment, using noise playbacks without surveillance calls, suggests that the increased vigilance could arise in part from the direct influence of additional noise as there was an increase in response to traffic-noise playback alone. Acoustic masking could also play a role. Foragers maintained the ability to distinguish between sentinels of different dominance class, increasing personal vigilance when presented with subordinate surveillance calls compared to calls of a dominant groupmate in both noise treatments, suggesting complete masking was not occurring. However, an acoustic-transmission experiment showed that while surveillance calls were potentially audible during approaching traffic noise, they were probably inaudible during peak traffic intensity noise. While recent work has demonstrated detrimental effects of anthropogenic noise on defensive responses to actual predatory attacks, which are relatively rare, our results provide evidence of a potentially more widespread influence since animals should constantly assess background risk to optimise the foraging-vigilance trade-off. Copyright © 2016 Elsevier Ltd. All rights reserved.

Habitat use and foraging patterns of molting male Long-tailed Ducks in lagoons of the central Beaufort Sea, Alaska

USGS Publications Warehouse

Flint, Paul L.; Reed, John; Deborah Lacroix,; Richard Lanctot,

2016-01-01

From mid-July through September, 10 000 to 30 000 Long-tailed Ducks (Clangula hyemalis) use the lagoon systems of the central Beaufort Sea for remigial molt. Little is known about their foraging behavior and patterns of habitat use during this flightless period. We used radio transmitters to track male Long-tailed Ducks through the molt period from 2000 to 2002 in three lagoons: one adjacent to industrial oil field development and activity and two in areas without industrial activity. We found that an index to time spent foraging generally increased through the molt period. Foraging, habitat use, and home range size showed similar patterns, but those patterns were highly variable among lagoons and across years. Even with continuous daylight during the study period, birds tended to use offshore areas during the day for feeding and roosted in protected nearshore waters at night. We suspect that variability in behaviors associated with foraging, habitat use, and home range size are likely influenced by availability of invertebrate prey. Proximity to oil field activity did not appear to affect foraging behaviors of molting Long-tailed Ducks.

Considerations on the Use of Exogenous Fibrolytic Enzymes to Improve Forage Utilization

PubMed Central

Mendoza, Germán D.; Plata-Pérez, Fernando X.

2014-01-01

Digestion of cell wall fractions of forage in the rumen is incomplete due to the complex links which limit their degradation. It is therefore necessary to find options to optimize the use of forages in ruminant production systems. One alternative is to use exogenous enzymes. Exogenous fibrolytic enzymes are of fungal or bacterial origin and increase nutrient availability from the cell wall, which consists of three fractions in different proportions depending on the species of forage: digestible, potentially digestible, and indigestible. The response to addition of exogenous enzymes varies with the type of forage; many researchers infer that there are enzyme-forage interactions but fail to explain the biological mechanism. We hypothesize that the response is related to the proportion of the potentially digestible fraction. The exogenous enzyme activity depends on several factors but if the general conditions for enzyme action are available, the potentially digestible fraction may determine the magnitude of the response. Results of experiments with exogenous fibrolytic enzymes in domestic ruminants are inconsistent. This, coupled with their high cost, has made their use unattractive to farmers. Development of cheaper products exploring other microorganisms with fibrolytic activity, such as Fomes fomentarius or Cellulomonas flavigena, is required. PMID:25379525

Nutrient-Mediated Architectural Plasticity of a Predatory Trap

PubMed Central

Blamires, Sean J.; Tso, I-Min

2013-01-01

Background Nutrients such as protein may be actively sought by foraging animals. Many predators exhibit foraging plasticity, but how their foraging strategies are affected when faced with nutrient deprivation is largely unknown. In spiders, the assimilation of protein into silk may be in conflict with somatic processes so we predicted web building to be affected under protein depletion. Methodology/Principal Findings To assess the influence of protein intake on foraging plasticity we fed the orb-web spiders Argiope aemula and Cyclosa mulmeinensis high, low or no protein solutions over 10 days and allowed them to build webs. We compared post-feeding web architectural components and major ampullate (MA) silk amino acid compositions. We found that the number of radii in webs increased in both species when fed high protein solutions. Mesh size increased in A. aemula when fed a high protein solution. MA silk proline and alanine compositions varied in each species with contrasting variations in alanine between the two species. Glycine compositions only varied in C. mulmeinensis silk. No spiders significantly lost or gained mass on any feeding treatment, so they did not sacrifice somatic maintenance for amino acid investment in silk. Conclusions/Significance Our results show that the amount of protein taken in significantly affects the foraging decisions of trap-building predators, such as orb web spiders. Nevertheless, the subtle differences found between species in the association between protein intake, the amino acids invested in silk and web architectural plasticity show that the influence of protein deprivation on specific foraging strategies differs among different spiders. PMID:23349928

Effects of small-scale clustering of flowers on pollinator foraging behaviour and flower visitation rate.

PubMed

Akter, Asma; Biella, Paolo; Klecka, Jan

2017-01-01

Plants often grow in clusters of various sizes and have a variable number of flowers per inflorescence. This small-scale spatial clustering affects insect foraging strategies and plant reproductive success. In our study, we aimed to determine how visitation rate and foraging behaviour of pollinators depend on the number of flowers per plant and on the size of clusters of multiple plants using Dracocephalum moldavica (Lamiaceae) as a target species. We measured flower visitation rate by observations of insects visiting single plants and clusters of plants with different numbers of flowers. Detailed data on foraging behaviour within clusters of different sizes were gathered for honeybees, Apis mellifera, the most abundant visitor of Dracocephalum in the experiments. We found that the total number of flower visitors increased with the increasing number of flowers on individual plants and in larger clusters, but less then proportionally. Although individual honeybees visited more flowers in larger clusters, they visited a smaller proportion of flowers, as has been previously observed. Consequently, visitation rate per flower and unit time peaked in clusters with an intermediate number of flowers. These patterns do not conform to expectations based on optimal foraging theory and the ideal free distribution model. We attribute this discrepancy to incomplete information about the distribution of resources. Detailed observations and video recordings of individual honeybees also showed that the number of flowers had no effect on handling time of flowers by honeybees. We evaluated the implications of these patterns for insect foraging biology and plant reproduction.

Effects of small-scale clustering of flowers on pollinator foraging behaviour and flower visitation rate

PubMed Central

2017-01-01

Plants often grow in clusters of various sizes and have a variable number of flowers per inflorescence. This small-scale spatial clustering affects insect foraging strategies and plant reproductive success. In our study, we aimed to determine how visitation rate and foraging behaviour of pollinators depend on the number of flowers per plant and on the size of clusters of multiple plants using Dracocephalum moldavica (Lamiaceae) as a target species. We measured flower visitation rate by observations of insects visiting single plants and clusters of plants with different numbers of flowers. Detailed data on foraging behaviour within clusters of different sizes were gathered for honeybees, Apis mellifera, the most abundant visitor of Dracocephalum in the experiments. We found that the total number of flower visitors increased with the increasing number of flowers on individual plants and in larger clusters, but less then proportionally. Although individual honeybees visited more flowers in larger clusters, they visited a smaller proportion of flowers, as has been previously observed. Consequently, visitation rate per flower and unit time peaked in clusters with an intermediate number of flowers. These patterns do not conform to expectations based on optimal foraging theory and the ideal free distribution model. We attribute this discrepancy to incomplete information about the distribution of resources. Detailed observations and video recordings of individual honeybees also showed that the number of flowers had no effect on handling time of flowers by honeybees. We evaluated the implications of these patterns for insect foraging biology and plant reproduction. PMID:29136042

Examining short-term nutritional status among BaAka foragers in transitional economies.

PubMed

Remis, Melissa J; Jost Robinson, Carolyn A

2014-07-01

Foragers in transitioning economies are at an increased risk of negative health outcomes as they undergo changes in subsistence patterns and diet. Here, we provide anthropometric data and examine the nutrition and health of adult BaAka foragers in relationship to declining wildlife and economic change in the Dzanga Sangha Protected Areas (APDS), Central African Republic. From June to August 2012, we collected biological data and dietary recall surveys from individuals in Mossapoula (MS) and Yandoumbé (YDBE) villages using standard anthropometric techniques and a single capillary blood finger prick. In our analysis, we identified variation in anthropometric measurements and hemoglobin levels by village (MS = 66, YDBE = 75) and gender (64 men, 77 women). Immigration, increased gun hunting and wildlife trades have reduced forager reliance on forest resources. These changes are evidenced in the marginal health of contemporary BaAka foragers of APDS. Although anthropometric measures of nutritional status do not significantly differ between communities, hemoglobin data highlight inequities in access to forest products between villages with different proximity to community hunting zones. Further, poor dietary diversity and low frequency of purchased foods in the diet indicate that the transition to a market economy has not been fully realized and diets are impoverished. Economic changes appear to have had the most impact at MS village, where forest use is most restricted and consumption of meat and forest products was reduced. This work highlights the nutritional and health needs of foragers in rapidly transitioning economies; especially those impacted by conservation management and zoning policies. © 2014 Wiley Periodicals, Inc.

Titrating the Cost of Plant Toxins Against Predators: a Case Study with Common Duikers, Sylvicapra grimmia.

PubMed

Abu Baker, Mohammad A

2015-10-01

Foragers face many variables that influence their food intake. These may include habitat structure, time, climate, resource characteristic, food quality, and plant defenses. I conducted foraging experiments using common duikers that involved: 1) testing the effect of plant toxins on foraging, and 2) titrating toxin intake against safety. I used giving up densities (GUDs, food remaining after foraging) to test for selection among trays containing alfalfa pellets treated with water, with 10% oxalic acid, or 10% quebracho tannin. Pairs of trays were placed within islands of woody vegetation and out in open grass. I also conducted a titration experiment by offering the duikers a choice between a patch with water-treated pellets placed at a risky site, or a patch with one of three oxalic acid-treated pellets at a safe site. This made it possible to determine the concentration of oxalic acid at which the cost of toxin in the safe site equals the predation cost at the risky site. The common duikers showed no selectivity among the three treatments at 10% concentration, however, GUDs in the open grass (i.e., safe) were significantly lower than in the wooded islands (i.e., risky). As the oxalic acid concentration increased at the safe sites, the duiker's food intake from the risky sites increased significantly. The results demonstrate that foraging hazards may come in different forms such as predation and plant toxins, and their interactions may alter habitat use, foraging patterns, and perceptions of risk. These variables occur under natural situations, altering the overall habitat quality.

Bats aggregate to improve prey search but might be impaired when their density becomes too high.

PubMed

Cvikel, Noam; Egert Berg, Katya; Levin, Eran; Hurme, Edward; Borissov, Ivailo; Boonman, Arjan; Amichai, Eran; Yovel, Yossi

2015-01-19

Social foraging is a very common yet extremely complex behavior. Numerous studies attempted to model it with little supporting evidence. Studying it in the wild is difficult because it requires monitoring the animal's movement, its foraging success, and its interactions with conspecifics. We present a novel system that enables full night ultrasonic recording of freely foraging bats, in addition to GPS tracking. As they rely on echolocation, audio recordings of bats allow tapping into their sensory acquisition of the world. Rapid changes in echolocation allowed us to reveal the bats' dynamic reactions in response to prey or conspecifics—two key behaviors that are extremely difficult to assess in most animals. We found that bats actively aggregate and forage as a group. However, we also found that when the group became too dense, bats were forced to devote sensory attention to conspecifics that frequently entered their biosonar "field of view," impairing the bats' prey detection performance. Why then did bats fly in such high densities? By emitting echolocation calls, bats constantly provide public information about their detection of prey. Bats could therefore benefit from intentionally flying at a distance that enables eavesdropping on conspecifics. Group foraging, therefore, probably allowed bats to effectively operate as an array of sensors, increasing their searching efficiency. We suggest that two opposing forces are at play in determining the efficient foraging density: on the one hand, higher densities improve prey detection, but on the other hand, they increase conspecific interference. Copyright © 2015 Elsevier Ltd. All rights reserved.

Ethanol concentration in food and body condition affect foraging behavior in Egyptian fruit bats ( Rousettus aegyptiacus)

NASA Astrophysics Data System (ADS)

Sánchez, Francisco; Korine, Carmi; Kotler, Burt P.; Pinshow, Berry

2008-06-01

Ethanol occurs in fleshy fruit as a result of sugar fermentation by both microorganisms and the plant itself; its concentration [EtOH] increases as fruit ripens. At low concentrations, ethanol is a nutrient, whereas at high concentrations, it is toxic. We hypothesized that the effects of ethanol on the foraging behavior of frugivorous vertebrates depend on its concentration in food and the body condition of the forager. We predicted that ethanol stimulates food consumption when its concentration is similar to that found in ripe fruit, whereas [EtOH] below or above that of ripe fruit has either no effect, or else deters foragers, respectively. Moreover, we expected that the amount of food ingested on a particular day of feeding influences the toxic effects of ethanol on a forager, and consequently shapes its feeding decisions on the following day. We therefore predicted that for a food-restricted forager, ethanol-rich food is of lower value than ethanol-free food. We used Egyptian fruit bats ( Rousettus aegyptiacus) as a model to test our hypotheses, and found that ethanol did not increase the value of food for the bats. High [EtOH] reduced the value of food for well-fed bats. However, for food-restricted bats, there was no difference between the value of ethanol-rich and ethanol-free food. Thus, microorganisms, via their production of ethanol, may affect the patterns of feeding of seed-dispersing frugivores. However, these patterns could be modified by the body condition of the animals because they might trade-off the costs of intoxication against the value of nutrients acquired.

Further assessment of the protozoal contribution to the nutrition of the ruminant animal.

PubMed

Hook, Sarah E; France, James; Dijkstra, Jan

2017-03-07

The flow of protozoa from the reticulo-rumen is lower than expected, due to ability of protozoa to prevent washout through sequestration on feed particles and the rumen epithelium. In order to estimate the distribution of protozoa within the reticulo-rumen and passage to the omasum, Czerkawski (1987) developed a model containing pools for the rumen liquid phase, rumen solid phase, and the omasum. This model was used to estimate loss of protozoa in the omasum as well as the amount of protozoal protein available to the animal in the lower gut. A number of assumptions were incorporated into the model, some of which appear unsupported by current research. This paper represents an update, revision, and re-evaluation of Czerkawski's model, where the assumptions that all protozoa in the 'attached' phase are in solid digesta, and that protozoa only leave the rumen in the liquid, have been relaxed. Therefore, the revised model allows for sequestration of protozoa on the rumen epithelium and protozoal passage with particulate outflow. Using experimental observations with inputs within biological limits, the revised model and Czerkawski's original model were verified. The effect of diet on the model was then assessed using inputs from a 100% forage diet and a 35-65% concentrate diet. The extent of sequestration was also varied from complete sequestration, to partial sequestration, and no sequestration. A sensitivity analysis was conducted through a linear regression of perturbed mean inputs versus outputs. The results from the revised model indicate that within the reticulo-rumen, the concentrate diet has a greater fractional flow rate of protozoa from the liquid to solid phase, but a lesser fractional flow rate back to the liquid phase, compared to the forage diet. As well, the concentrate diet has a slower net growth rate of protozoa in the attached phase, compared to the forage diet. In the omasum, the forage diet has a less negative net growth rate, compared to the concentrate diet. The forage diet was also associated with smaller loss of protozoa from the omasum. There are limited data from the omasum to be incorporated into the revised model, especially for quantity of protozoa in the omasum. Further research on quantification of protozoa in the omasum could strengthen the predictions made by the model. Despite this, the revised model found a loss of protozoa in the omasum similar to that suggested by Czerkawski's original model 65-73% versus 66%. The revised model results indicate that efforts to increase protozoal flow to the duodenum should focus on reduced sequestration and increased outflow rate from the rumen, although more research is needed to quantify protozoa in the omasum, and to investigate the role of sequestration onto the wall of the reticulo-rumen. Copyright © 2016 Elsevier Ltd. All rights reserved.

Food resources of the California condor

USGS Publications Warehouse

Wilbur, S.R.

1972-01-01

Conclusions and Recommendations: Although much of the above information is imprecise and inconclusive, it is evident that the condors foraging habitat is diminishing. Food supply probably is still adequate for free-ranging nonbreeding birds, but could become limited if current land use trends continue. Congregating condors on fewer and fewer acres could be detrimental in other ways. It seems the needs of condors can best be met by maintaining a continuous band of :foraging country throughout the species' horseshoe-shaped range. Public needs for open space and livestock agriculture can also be served by land use zoning, cooperative agreements, easements or other land controls implemented with consideration :for the condors' welfare. Of immediate concern is the declining food situation in the general vicinity of the active condor nests in the Sespe-Piru region. Reproduction is definitely depressed, and the reduced local food supply is the only apparent cause. Predicted future developments can only worsen the situation. A concerted effort should be made immediately to slow the loss of food and foraging area closest to the Sespe Condor Sanctuary including: (1) the Big Mountain-Newhall Ranch regions of southern Ventura County; (2) the arc of grassland around the southern and eastern boundaries of the Sespe Sanctuary; and (3) the Tejon Ranch. Within these areas efforts should be made to increase the amount of condor food by: (1) increasing the amount of livestock, if compatible with proper land use; (2) modifying procedures for disposal of dead livestock, so that more are available to condors; (3) encouraging (subsidizing) ranchers to sacrifice livestock for condor food at certain times o:f the year; and (4) developing a state or Federal supplemental feeding program utilizing cattle, deer or other carrion regularly distributed at close, protected feeding sites. If a convenient food supply is as important to reproduction as it appears, those nest sites closest to the best food source may become most productive and significant in the preservation of this species. These sites, which are in the Piru Creek area, are outside the boundaries o:f the Sespe Condor Sanctuary, but are recognized by the U.S. Forest Service (1971) as extremely important to condor survival. Protective measures recommended in the Forest Service plan should be implemented as soon as possible to preserve this area's usefulness as condor nesting habitat. Food may not be the factor currently limiting condor reproduction. However, the reproductive rate is inadequate to sustain the condor population for long. As food shortage has been shown to limit breeding in many species (Lack 1954, 1966), and as it is something which can be manipulated, it is a logical factor for further study and experimentation.

Cotton Rats Alter Foraging in Response to an Invasive Ant.

PubMed

Darracq, Andrea K; Conner, L Mike; Brown, Joel S; McCleery, Robert A

We assessed the effects of red imported fire ants (Solenopsis invicta; hereafter fire ant) on the foraging of hispid cotton rats (Sigmodon hispidus). We used a manipulative experiment, placing resource patches with a known amount of millet seed within areas with reduced (RIFA [-]) or ambient (RIFA [+]) numbers of fire ants. We measured giving up densities (the amount of food left within each patch) within the resource patches for 4 days to quantify the effects of fire ants on cotton rat foraging. We assessed the effects of fire ant treatment (RIFA), Day, and their interaction on cotton rat giving up densities. Giving up densities on RIFA [+] grids were nearly 2.2 times greater across all foraging days and ranged from 1.6 to 2.3 times greater from day 1 to day 4 than the RIFA [-] grids. From day 1 to day 4, mean giving up densities decreased significantly faster for the RIFA [-] than RIFA [+] treatments, 58% and 13%, respectively. Our results demonstrate that cotton rats perceive a risk of injury from fire ants, which is likely caused by interference competition, rather than direct predation. Envenomation from ants likely decrease the foraging efficiency of cotton rats resulting in more time spent foraging. Increased time spent foraging is likely stressful in terms of the opportunity for direct injury and encounters with other predators. These indirect effects may reduce an individual cotton rat's fitness and translate into lowered population abundances.

Intraspecific Variation among Social Insect Colonies: Persistent Regional and Colony-Level Differences in Fire Ant Foraging Behavior

PubMed Central

Bockoven, Alison A.; Wilder, Shawn M.; Eubanks, Micky D.

2015-01-01

Individuals vary within a species in many ecologically important ways, but the causes and consequences of such variation are often poorly understood. Foraging behavior is among the most profitable and risky activities in which organisms engage and is expected to be under strong selection. Among social insects there is evidence that within-colony variation in traits such as foraging behavior can increase colony fitness, but variation between colonies and the potential consequences of such variation are poorly documented. In this study, we tested natural populations of the red imported fire ant, Solenopsis invicta, for the existence of colony and regional variation in foraging behavior and tested the persistence of this variation over time and across foraging habitats. We also reared single-lineage colonies in standardized environments to explore the contribution of colony lineage. Fire ants from natural populations exhibited significant and persistent colony and regional-level variation in foraging behaviors such as extra-nest activity, exploration, and discovery of and recruitment to resources. Moreover, colony-level variation in extra-nest activity was significantly correlated with colony growth, suggesting that this variation has fitness consequences. Lineage of the colony had a significant effect on extra-nest activity and exploratory activity and explained approximately half of the variation observed in foraging behaviors, suggesting a heritable component to colony-level variation in behavior. PMID:26197456

The ontogeny of handling hard-to-process food in wild brown capuchins (Cebus apella apella): evidence from foraging on the fruit of Maximiliana maripa.

PubMed

Gunst, Noëlle; Leca, Jean-Baptiste; Boinski, Sue; Fragaszy, Dorothy

2010-11-01

We examined age-related differences in wild brown capuchins' foraging efficiency and the food-processing behaviors directed toward maripa palm fruit (Maximiliana maripa). A detailed comparison of the different foraging techniques showed that plucking the fruit from the infructescence constituted the main difficulty of this task. Foraging efficiency tended to increase with age, with a threshold at which sufficient strength allowed immatures by the age of three to reach adult-level efficiency. Youngsters spent more time than older individuals browsing the infructescence and pulling the fruit in an attempt to harvest it. Infants tried to compensate for their inability to pluck fruit by adopting alternative strategies but with low payback, such as gnawing unplucked fruit and opportunistically scrounging others' partially processed food. Although around 2 years of age, young capuchins exhibited all of the behaviors used by adults, they did not reach adult-level proficiency at feeding on maripa until about 3 years (older juveniles). We compared this developmental pattern with that of extractive foraging on beetle larvae (Myelobia sp.) hidden in bamboo stalks, a more difficult food for these monkeys [Gunst N, Boinski S, Fragaszy DM. Behaviour 145:195-229, 2008]. For maripa, the challenge was mainly physical (plucking the fruit) once a tree was encountered, whereas for larvae, the challenge was primarily perceptual (locating the hidden larvae). For both foods, capuchins practice for years before achieving adult-level foraging competence, and the timeline is extended for larvae foraging (until 6 years) compared with maripa (3 years). The differing combinations of opportunities and challenges for learning to forage on these different foods illustrate how young generalist foragers (i.e. exploiting a large number of animal and plant species) may compensate for their low efficiency in extractive foraging tasks by showing earlier competence in processing less difficult but nutritious foods, such as maripa fruit. © 2010 Wiley-Liss, Inc.

Foraging behavior of redheads (Aythya americana) wintering in Texas and Louisiana

USGS Publications Warehouse

Woodin, M.C.; Michot, T.C.

2006-01-01

Redheads, Aythya americana, concentrate in large numbers annually in traditional wintering areas along the western and northern rim of the Gulf of Mexico. Two of these areas are the Laguna Madre of Texas and Chandeleur Sound of Louisiana. We collected data on 54,340 activities from 103 redhead flocks in Texas and 51,650 activities from 57 redhead flocks in Louisiana. Males and females fed similarly, differing neither in levels of feeding (percent of all birds in flock that were feeding) (p>0.90) nor in percentages of birds feeding by diving, tipping, dipping, or gleaning from the surface (p>0.10). The foraging level of redheads in the upper Laguna Madre region was relatively constant throughout two winters. Foraging of redheads in early winter in Louisiana was significantly greater than redhead foraging in the upper Laguna Madre, but by late winter, foraging by redheads in Louisiana had declined to the same level as that shown by redheads foraging in the upper Laguna Madre. The overall foraging level of redheads from Chandeleur Sound was greater (41%) than that of redheads in the upper Laguna Madre (26%), yet it was quite similar to the 46% foraging level reported for redheads from the lower Laguna Madre. Redheads in the upper Laguna Madre region of Texas fed more by diving than did those in the Chandeleur Sound and the lower Laguna Madre. Diving increased in frequency in late winter. Greater reliance by redheads on diving in January and February indicates that the birds altered their foraging to feed in deeper water, suggesting that the large concentrations of redheads staging at this time for spring migration may have displaced some birds to alternative foraging sites. Our results imply that the most likely period for food resources to become limiting for wintering redheads is when they are staging in late winter. ?? Springer 2006.

Individual Foraging Strategies Reveal Niche Overlap between Endangered Galapagos Pinnipeds

PubMed Central

Villegas-Amtmann, Stella; Jeglinski, Jana W. E.; Costa, Daniel P.; Robinson, Patrick W.; Trillmich, Fritz

2013-01-01

Most competition studies between species are conducted from a population-level approach. Few studies have examined inter-specific competition in conjunction with intra-specific competition, with an individual-based approach. To our knowledge, none has been conducted on marine top predators. Sympatric Galapagos fur seals (Arctocephalus galapagoensis) and sea lions (Zalophus wollebaeki) share similar geographic habitats and potentially compete. We studied their foraging niche overlap at Cabo Douglas, Fernandina Island from simultaneously collected dive and movement data to examine spatial and temporal inter- and intra-specific competition. Sea lions exhibited 3 foraging strategies (shallow, intermediate and deep) indicating intra-specific competition. Fur seals exhibited one foraging strategy, diving predominantly at night, between 0–80 m depth and mostly at 19–22 h. Most sea lion dives also occurred at night (63%), between 0–40 m, within fur seals' diving depth range. 34% of sea lions night dives occurred at 19–22 h, when fur seals dived the most, but most of them occurred at dawn and dusk, when fur seals exhibited the least amount of dives. Fur seals and sea lions foraging behavior overlapped at 19 and 21 h between 0–30 m depths. Sea lions from the deep diving strategy exhibited the greatest foraging overlap with fur seals, in time (19 h), depth during overlapping time (21–24 m), and foraging range (37.7%). Fur seals foraging range was larger. Cabo Douglas northwest coastal area, region of highest diving density, is a foraging “hot spot” for both species. Fur seals and sea lions foraging niche overlap occurred, but segregation also occurred; fur seals primarily dived at night, while sea lions exhibited night and day diving. Both species exploited depths and areas exclusive to their species. Niche breadth generally increases with environmental uncertainty and decreased productivity. Potential competition between these species could be greater during warmer periods when prey availability is reduced. PMID:23967096

Male songbirds provide indirect parental care by guarding females during incubation

USGS Publications Warehouse

Fedy, B.C.; Martin, T.E.

2009-01-01

Across many taxa, guarding of fertile mates is a widespread tactic that enhances paternity assurance. However, guarding of mates can also occur during the nonfertile period, and the fitness benefits of this behavior are unclear. Male songbirds, for example, sometimes guard nonfertile females during foraging recesses from incubation. We hypothesized that guarding postreproductive mates may have important, but unrecognized, benefits by enhancing female foraging efficiency, thereby increasing time spent incubating eggs. We tested the hypothesis in 2 songbird species by examining female behavior during natural and experimentally induced absences of males. Male absence caused increased vigilance in foraging females that decreased their efficiency and resulted in less time spent incubating eggs. Male guarding of nonfertile females can thus provide a previously unrecognized form of indirect parental care.

Winter use of sea ice and ocean water mass habitat by southern elephant seals: The length and breadth of the mystery

NASA Astrophysics Data System (ADS)

Labrousse, Sara; Vacquié-Garcia, Jade; Heerah, Karine; Guinet, Christophe; Sallée, Jean-Baptiste; Authier, Matthieu; Picard, Baptiste; Roquet, Fabien; Bailleul, Frédéric; Hindell, Mark; Charrassin, Jean-Benoit

2015-09-01

Understanding the responses of animals to the environment is crucial for identifying critical foraging habitat. Elephant seals (Mirounga leonina) from the Kerguelen Islands (49°20‧S, 70°20‧E) have several different foraging strategies. Why some individuals undertake long trips to the Antarctic continent while others utilize the relatively close frontal zones is poorly understood. Here, we investigate how physical properties within the sea ice zone are linked to foraging activities of southern elephant seals (SES). To do this, we first developed a new approach using indices of foraging derived from high temporal resolution dive and accelerometry data to predict foraging behaviour in an extensive, low resolution dataset from CTD-Satellite Relay Data Loggers (CTD-SRDLs). A sample of 37 post-breeding SES females were used to construct a predictive model applied to demersal and pelagic dive strategies relating prey encounter events (PEE) to dive parameters (dive duration, bottom duration, hunting-time, maximum depth, ascent speed, descent speed, sinuosity, and horizontal speed) for each strategy. We applied these models to a second sample of 35 seals, 20 males and 15 females, during the post-moult foraging trip to the Antarctic continental shelf between 2004 and 2013, which did not have fine-scale behavioural data. The females were widely distributed with important foraging activity south of the Southern Boundary Front, while males predominately travelled to the south-eastern part of the East Antarctica region. Combining our predictions of PEE with environmental features (sea ice concentration, water masses at the bottom phase of dives, bathymetry and slope index) we found higher foraging activity for females over shallower seabed depths and at the boundary between the overlying Antarctic Surface Water (AASW) and the underlying Modified Circumpolar Deep Water (MCDW). Increased biological activity associated with the upper boundary of MCDW, may provide overwintering areas for SES prey. Male foraging activity was strongly associated with pelagic dives within the Antarctic Slope Front where upwelling of nutrient rich Circumpolar Deep Water onto surface water may enhance and concentrate resources. A positive association between sea ice and foraging activity was found for both sexes where increased biological activity may sustain an under-ice ecosystem. Variability of the East Antarctic sea ice season duration is likely a crucial element to allow air-breathing predators to benefit from profitable prey patches within the pack ice habitat.

The impact of different hydrographic conditions and zooplankton communities on provisioning Little Auks along the West coast of Spitsbergen

NASA Astrophysics Data System (ADS)

Kwasniewski, Slawomir; Gluchowska, Marta; Jakubas, Dariusz; Wojczulanis-Jakubas, Katarzyna; Walkusz, Wojciech; Karnovsky, Nina; Blachowiak-Samolyk, Katarzyna; Cisek, Malgorzata; Stempniewicz, Lech

2010-10-01

Composition and abundance of zooplankton were studied simultaneously with feeding ecology of planktivorous Little Auks ( Alle alle) in two different sea shelf areas of West Spitsbergen, Norway, in summer 2007. Zooplankton was collected adjacent to bird colonies in Magdalenefjorden (influenced by Atlantic West Spitsbergen Current) and Hornsund (dominated by the Arctic Sørkapp Current). In spite of different hydrological situations, the abundance of prey preferred by Little Auks, Arctic Calanus glacialis copepodids stage V, among zooplankton was similar in both localities. However, there was much more of Atlantic Calanus finmarchicus on the shelf outside Magdalenefjorden compared to Hornsund, resulting in different abundance ratios of Arctic to Atlantic copepods in the two areas (1:14 and 1:1, respectively). Even greater differences between the two areas occurred in the ratio of C. glacialis CV to other zooplankters, amounting to 1:40 in Magdalenefjorden and 1:6 in Hornsund. In both Little Auk colonies food brought by parents to their chicks contained mainly C. glacialis CV, albeit the proportion of this copepod in meals was significantly higher in Hornsund. Meals delivered to Little Auk chicks in Hornsund had also higher zooplankton numbers, biomass and energy content. In Magdalenefjorden, on the other hand, a higher number of feedings and longer duration of foraging trips were recorded. These differences became more apparent with increasing energy requirements of the fast growing nestlings. This was probably a consequence of lower relative abundance of the Little Auks’ preferred prey in the sea adjacent to Magdalenefjorden colony. It seems that searching for the preferred food items, such as C. glacialis, among abundant but less favored C. finmarchicus, may require more time and energy demanding foraging behavior. As a consequence, foraging effort of the Little Auk parents from Magdalenefjorden was higher, and feeding efficiency lower, than those of birds from Hornsund. Increasing influx of warm Atlantic waters that bring boreal zooplankton to the Arctic Seas may have negative impacts on Little Auks’ time and energy budgets and eventually on their breeding success and range of breeding distribution.

Can cover crops pull double duty: Conservation and profitable forage production in the Midwestern U.S.?

USDA-ARS?s Scientific Manuscript database

Data from a recent survey suggests that the major reasons Nebraska farmer’s plant cover crops are to: improve soil organic matter, reduce erosion, improve soil water holding capacity, produce forage, and increase soil microbial biomass. Many of these benefits appear to be positively correlated with...

Evaluation of sprouted barley fodder production systems on organic dairy farms in temperate regions of the United States

USDA-ARS?s Scientific Manuscript database

Take home Message Producing high-quality forage is more economical than producing fodder for US organic dairy farms Introduction Organic dairy farmers have shown increased interest in growing sprouted barley fodder in temperate regions of the United States where producing high-quality forage has b...

Elevated CO2 induces substantial and persistent declines in forage quality irrespective of warming in mixed grass prairie

USDA-ARS?s Scientific Manuscript database

Increasing atmospheric [CO2] and temperature are expected to affect the productivity, species composition, biogeochemistry, and therefore the quantity and quality of forage available to herbivores in rangeland ecosystems. Both elevated CO2 (eCO2) and warming affect plant tissue chemistry through mul...

Animal impacts

Treesearch

Norbert V. DeByle

1985-01-01

The aspen ecosystem is rich in number and species of animals, especially in comparison to associated coniferous forest types. This natural species diversity and richness has been both increased and influenced by the introduction of domestic livestock. The high value of the aspen type as a forage resource for livestock and as forage and cover for wildlife makes the...

Dairy farmers using mob grazing in Pennsylvania and New York

USDA-ARS?s Scientific Manuscript database

Proponents of ultra-high stocking density grazing emphasize increased forage use efficiency and soil improvement by grazing mature forage with stocking densities up to 500,000 lb per acre of beef cattle on small paddocks with rest periods up to 180 days. However, it is unclear if this management tec...

Domestic cats and dogs create a landscape of fear for pest rodents around rural homesteads.

PubMed

Mahlaba, Themb'alilahlwa A M; Monadjem, Ara; McCleery, Robert; Belmain, Steven R

2017-01-01

Using domestic predators such as cats to control rodent pest problems around farms and homesteads is common across the world. However, practical scientific evidence on the impact of such biological control in agricultural settings is often lacking. We tested whether the presence of domestic cats and/or dogs in rural homesteads would affect the foraging behaviour of pest rodents. We estimated giving up densities (GUDs) from established feeding patches and estimated relative rodent activity using tracking tiles at 40 homesteads across four agricultural communities. We found that the presence of cats and dogs at the same homestead significantly reduced activity and increased GUDs (i.e. increased perception of foraging cost) of pest rodent species. However, if only cats or dogs alone were present at the homestead there was no observed difference in rodent foraging activity in comparison to homesteads with no cats or dogs. Our results suggest that pest rodent activity can be discouraged through the presence of domestic predators. When different types of predator are present together they likely create a heightened landscape of fear for foraging rodents.

Distribution and diurnal behavior of Steller's Eiders wintering on the Alaska Peninsula

USGS Publications Warehouse

Laubhan, M.K.; Metzner, K.A.

1999-01-01

We studied the distribution and activities of adult Steller's Eiders (Polysticta stelleri) during winter and spring on a deep-water embayment and a shallow lagoon along the Alaska Peninsula from September 1980 to May 1981. During the remigial molt, eiders were observed on Izembek Lagoon but not on Cold Bay. Following the flightless period, Izembek Lagoon continued to support 63-100% of eiders encountered during surveys. As ice cover on Izembek Lagoon increased, the number of birds decreased on Izembek Lagoon but increased on Cold Bay, suggesting that some eiders disperse to nearshore, deep-water habitats in close proximity to Izembek Lagoon during severe weather. Diurnal activity budgets indicated that the amount of time resting or engaged in aggression and alert activities was similar among locations, seasons, tidal stages, and sexes. In contrast, time spent foraging differed among seasons and locations but did not differ among tidal stages or sexes. Although time spent foraging was similar during winter and spring on Izembek Lagoon, eiders on Cold Bay foraged more during winter compared to spring. Synchronous diving was the dominant foraging strategy.

Guild-specific responses of avian species richness to LiDAR-derived habitat heterogeneity

USGS Publications Warehouse

Weisberg, Peter J.; Dilts, Thomas E.; Becker, Miles E.; Young, Jock S.; Wong-Kone, Diane C.; Newton, Wesley E.; Ammon, Elisabeth M.

2014-01-01

Ecological niche theory implies that more heterogeneous habitats have the potential to support greater biodiversity. Positive heterogeneity-diversity relationships have been found for most studies investigating animal taxa, although negative relationships also occur and the scale dependence of heterogeneity-diversity relationships is little known. We investigated multi-scale, heterogeneity-diversity relationships for bird communities in a semi-arid riparian landscape, using airborne LiDAR data to derive key measures of structural habitat complexity. Habitat heterogeneity-diversity relationships were generally positive, although the overall strength of relationships varied across avian life history guilds (R2 range: 0.03–0.41). Best predicted were the species richness indices of cavity nesters, habitat generalists, woodland specialists, and foliage foragers. Heterogeneity-diversity relationships were also strongly scale-dependent, with strongest associations at the 200-m scale (4 ha) and weakest associations at the 50-m scale (0.25 ha). Our results underscore the value of LiDAR data for fine-grained quantification of habitat structure, as well as the need for biodiversity studies to incorporate variation among life-history guilds and to simultaneously consider multiple guild functional types (e.g. nesting, foraging, habitat). Results suggest that certain life-history guilds (foliage foragers, cavity nesters, woodland specialists) are more susceptible than others (ground foragers, ground nesters, low nesters) to experiencing declines in local species richness if functional elements of habitat heterogeneity are lost. Positive heterogeneity-diversity relationships imply that riparian conservation efforts need to not only provide high-quality riparian habitat locally, but also to provide habitat heterogeneity across multiple scales.

Preparation and use of varied natural tools for extractive foraging by bonobos (Pan Paniscus).

PubMed

Roffman, Itai; Savage-Rumbaugh, Sue; Rubert-Pugh, Elizabeth; Stadler, André; Ronen, Avraham; Nevo, Eviatar

2015-09-01

The tool-assisted extractive foraging capabilities of captive (zoo) and semi-captive (sanctuary) bonobo (Pan paniscus) groups were compared to each other and to those known in wild chimpanzee (Pan troglodytes) cultures. The bonobos were provided with natural raw materials and challenged with tasks not previously encountered, in experimental settings simulating natural contexts where resources requiring special retrieval efforts were hidden. They were shown that food was buried underground or inserted into long bone cavities, and left to tackle the tasks without further intervention. The bonobos used modified branches and unmodified antlers or stones to dig under rocks and in the ground or to break bones to retrieve the food. Antlers, short sticks, long sticks, and rocks were effectively used as mattocks, daggers, levers, and shovels, respectively. One bonobo successively struck a long bone with an angular hammer stone, completely bisecting it longitudinally. Another bonobo modified long branches into spears and used them as attack weapons and barriers. Bonobos in the sanctuary, unlike those in the zoo, used tool sets to perform sequential actions. The competent and diverse tool-assisted extractive foraging by the bonobos corroborates and complements the extensive information on similar tool use by chimpanzees, suggesting that such competence is a shared trait. Better performance by the sanctuary bonobos than the zoo group was probably due to differences in their cultural exposure and housing conditions. The bonobos' foraging techniques resembled some of those attributed to Oldowan hominins, implying that they can serve as referential models. © 2015 Wiley Periodicals, Inc.

Guild-specific responses of avian species richness to LiDAR-derived habitat heterogeneity

NASA Astrophysics Data System (ADS)

Weisberg, Peter J.; Dilts, Thomas E.; Becker, Miles E.; Young, Jock S.; Wong-Kone, Diane C.; Newton, Wesley E.; Ammon, Elisabeth M.

2014-08-01

Ecological niche theory implies that more heterogeneous habitats have the potential to support greater biodiversity. Positive heterogeneity-diversity relationships have been found for most studies investigating animal taxa, although negative relationships also occur and the scale dependence of heterogeneity-diversity relationships is little known. We investigated multi-scale, heterogeneity-diversity relationships for bird communities in a semi-arid riparian landscape, using airborne LiDAR data to derive key measures of structural habitat complexity. Habitat heterogeneity-diversity relationships were generally positive, although the overall strength of relationships varied across avian life history guilds (R2 range: 0.03-0.41). Best predicted were the species richness indices of cavity nesters, habitat generalists, woodland specialists, and foliage foragers. Heterogeneity-diversity relationships were also strongly scale-dependent, with strongest associations at the 200-m scale (4 ha) and weakest associations at the 50-m scale (0.25 ha). Our results underscore the value of LiDAR data for fine-grained quantification of habitat structure, as well as the need for biodiversity studies to incorporate variation among life-history guilds and to simultaneously consider multiple guild functional types (e.g. nesting, foraging, habitat). Results suggest that certain life-history guilds (foliage foragers, cavity nesters, woodland specialists) are more susceptible than others (ground foragers, ground nesters, low nesters) to experiencing declines in local species richness if functional elements of habitat heterogeneity are lost. Positive heterogeneity-diversity relationships imply that riparian conservation efforts need to not only provide high-quality riparian habitat locally, but also to provide habitat heterogeneity across multiple scales.

Barley processing, forage:concentrate, and forage length effects on chewing and digesta passage in lactating cows.

PubMed

Yang, W Z; Beauchemin, K A; Rode, L M

2001-12-01

Dietary factors that alter fermentability, NDF content, or particle size of the diet were evaluated for their effects on chewing behavior and distribution and passage of feed particles in the digestive tract of dairy cows. A double 4 x 4 quasi-Latin square design with a 2(3) factorial arrangement of treatments was used. The dietary factors were: extent of barley grain processing, coarse (1.60 mm) or flat (1.36 mm); forage-to-concentrate ratio (F:C), low (35:65) or high (55:45) (dry matter basis); and forage particle length, long (7.59 mm) or short (6.08 mm). Eight lactating cows with ruminal and duodenal cannulas were offered ad libitum access to total mixed diets. Chewing time, expressed as minutes per day or per kilogram of dry matter or neutral detergent fiber (NDF), was increased with high F:C diets due to increased eating and ruminating times but was decreased when expressed per kilogram of NDF intake from forage. The influence of forage particle length or grain processing on chewing activity was less pronounced than F:C ratio. Chewing activity was positively correlated to proportion of long forage particles in the diet but not to particle length of the diets. Influence of feed particle size on particle size distribution in different sites of the digestive tract was minimal. Particle size distributions of duodenal digesta and feces differed; the proportion of particles retained on the 3.35- or 1.18-mm screens was higher, but proportion of particles that passed through the 1.18-mm screen was lower in duodenal digesta than in feces. Relationships between chewing activities and ruminal pH or fractional passage rate of rumen contents were not significant. These results indicate that particle size of barley-based diets was not a reliable indicator of chewing activity. Forage particle size and NDF content of the diets were more reliable indicators of chewing activity than was the NDF content of forage. Fecal particle size was not an appropriate means of estimating the size of particles exiting the reticulorumen, at least for barley-based diets. Breakdown of coarse particles was necessary, but not a rate-limiting step for particles exiting the rumen. Passage rate of the rumen contents was affected by numerous factors including chewing activity.

Nitrous oxide emission factors for urine and dung from sheep fed either fresh forage rape (Brassica napus L.) or fresh perennial ryegrass (Lolium perenne L.).

PubMed

Luo, J; Sun, X Z; Pacheco, D; Ledgard, S F; Lindsey, S B; Hoogendoorn, C J; Wise, B; Watkins, N L

2015-03-01

In New Zealand, agriculture is predominantly based on pastoral grazing systems and animal excreta deposited on soil during grazing have been identified as a major source of nitrous oxide (N2O) emissions. Forage brassicas (Brassica spp.) have been increasingly used to improve lamb performance. Compared with conventional forage perennial ryegrass (Lolium perenne L.), a common forage in New Zealand, forage brassicas have faster growth rates, higher dry matter production and higher nutritive value. The aim of this study was to determine the partitioning of dietary nitrogen (N) between urine and dung in the excreta from sheep fed forage brassica rape (B. napus subsp. oleifera L.) or ryegrass, and then to measure N2O emissions when the excreta from the two different feed sources were applied to a pasture soil. A sheep metabolism study was conducted to determine urine and dung-N outputs from sheep fed forage rape or ryegrass, and N partitioning between urine and dung. Urine and dung were collected and then used in a field plot experiment for measuring N2O emissions. The experimental site contained a perennial ryegrass/white clover pasture on a poorly drained silt-loam soil. The treatments included urine from sheep fed forage rape or ryegrass, dung from sheep fed forage rape or ryegrass, and a control without dung or urine applied. N2O emission measurements were carried out using a static chamber technique. For each excreta type, the total N2O emissions and emission factor (EF3; N2O-N emitted during the 3- or 8-month measurement period as a per cent of animal urine or dung-N applied, respectively) were calculated. Our results indicate that, in terms of per unit of N intake, a similar amount of N was excreted in urine from sheep fed either forage rape or ryegrass, but less dung N was excreted from sheep fed forage rape than ryegrass. The EF3 for urine from sheep fed forage rape was lower compared with urine from sheep fed ryegrass. This may have been because of plant secondary metabolites, such as glucosinolates in forage rape and their degradation products, are transferred to urine and affect soil N transformation processes. However, the difference in the EF3 for dung from sheep fed ryegrass and forage rape was not significant.

Relationship between chemical composition of native forage and nutrient digestibility by Tibetan sheep on the Qinghai-Tibetan Plateau.

PubMed

Yang, Chuntao; Gao, Peng; Hou, Fujiang; Yan, Tianhai; Chang, Shenghua; Chen, Xianjiang; Wang, Zhaofeng

2018-04-02

To better utilize native pasture at the high altitude region, three-consecutive-year feeding experiments and a total of seven metabolism trials were conducted to evaluate the impact of three forage stages of maturity on the chemical composition, nutrient digestibility, and energy metabolism of native forage in Tibetan sheep on the Qinghai-Tibetan Plateau (QTP). Forages were harvested from June to July, August to October, and November to December of 2011 to 2013, corresponding to the vegetative, bloom, and senescent stages of the annual forages. Twenty male Tibetan sheep were selected for each study and fed native forage ad libitum. The digestibility of DM, OM, CP, NDF, ADF, DE, DE/GE, and ME/GE were greatest (P < 0.01) from the vegetative stage, intermediate (P < 0.01) from the bloom stage, and least (P < 0.01) from the senescent stage. Nutrient digestibility and energy parameters correlated positively (linear, 0.422 to 0.778; quadratic, 0.568 to 0.815; P < 0.01) with the CP content of forage but correlated negatively with the content of NDF (linear, 0.343 to 0.689; quadratic, 0.444 to 0.777; P ≤ 0.02), ADF (linear, 0.563 to 0.766; quadratic, 0.582 to 0.770; P < 0.01), and ether extract (EE, linear, 0.283 to 0.574; quadratic, 0.366 to 0.718; P ≤ 0.04) of forage. For each predicted variable, the prediction of DMI expressed as grams per kilogram of BW (g/kg BW·d) yielded a greater R2 value (0.677 to 0.761 vs. 0.616 to 0.711) compared with the equations of DMI expressed as g/kg metabolic BW by step-wise regression. The results suggest that parameters of forage CP, NDF, and ADF content were most closely related to nutrient digestibility. Contrary to previous studies, in this study, ADF content had a greater linear relationship (0.766 vs. 0.563 to 0.732) with OM digestibility than the other parameters of nutrient digestibility. The quadratic relationship between forage CP content and CP digestibility indicates that when forage CP content exceeds the peak point (9.7% DM in the present study), increasing forage CP content could decrease CP digestibility when Tibetan sheep were offered native forage alone on the QTP. Additionally, using the forage CP, EE, NDF, and ADF content to predict DMI (g/kg BW·d) yielded the best fit equation for Tibetan sheep living in the northeast portion of the QTP.

The effect of supplemental food on the growth rates of neonatal, young, and adult cotton rats ( Sigmodon hispidus) in northeastern Kansas, USA

NASA Astrophysics Data System (ADS)

Eifler, Maria A.; Slade, Norman A.; Doonan, Terry J.

2003-09-01

In food-limited populations, the presence of extra food resources can influence the way individuals allocate energy to growth and reproduction. We experimentally increased food available to cotton rats ( Sigmodon hispidus) near the northern limit of their range over a 2-year period and tested the hypothesis that seasonal growth rates would be enhanced by supplemental food during winter and spring when natural food levels are low. We also examined whether additional food resources were allocated to somatic growth or reproductive effort by pregnant and lactating females. The effect of supplemental food on growth varied with mass and season, but did not influence the growth rates of most cotton rats during spring and winter. In winter, small animals on supplemented grids had higher growth rates than small animals on control grids, but females in spring had lower growth rates under supplemented conditions. Growth rates of supplemented cotton rats were enhanced in summer. Northern cotton rat populations may use season-specific foraging strategies, maximizing energy intake during the reproductive season and minimizing time spent foraging in winter. Adult females invest extra resources in reproduction rather than in somatic growth. Pregnant females receiving supplemental food had higher growth rates than control females, and dependent pups (≤ 1 month of age) born to supplemented mothers had higher growth rates than those born to control mothers. Increased body size seems to confer an advantage during the reproductive season, but has no concomitant advantage to overwinter survival.

Effects of forage species or concentrate finishing on animal performance, carcass and meat quality.

PubMed

Duckett, S K; Neel, J P S; Lewis, R M; Fontenot, J P; Clapham, W M

2013-03-01

Angus-cross steers (n = 128; initial BW = 270 ± 3.8 kg) were used in a 3-yr study to assess effects of forage species grazed before slaughter versus concentrate finishing on carcass and meat quality. At the completion of the stockering phase, steers were randomly allotted to mixed pasture (MP; n = 36/yr) or corn-silage concentrate (CON; n = 12/yr) finishing treatments. At 40 d before harvest, MP steers were randomly divided into 3 forage species treatments: alfalfa (AL), pearl millet (PM), or mixed pasture (MP). Average daily BW gain was greater (P = 0.001) for CON than for forage-finished (FOR) steers during the early and overall finishing phase. During the late finishing phase when FOR steers were grazing difference forage species, ADG was greater (P = 0.03) for PM than MP or AL. Harvest weight and HCW were greater (P < 0.001) for CON than FOR due to the differences in animal performance. Total fat percentage of the 9th to 11th rib section was 46% less(P = 0.028) for FOR than CON due to reductions (P < 0.001) in the percentage of subcutaneous fat. Warner-Bratzler shear force (WBS) values at 14 d and 28 d of aging did not differ (P > 0.78) between CON and FOR and were not altered (P > 0.40) by forage species. Trained sensory panel juiciness, initial tenderness, and overall tenderness scores did not differ (P > 0.17) by finishing treatment or forage species. Beef flavor intensity was greater (P < 0.001) for CON than FOR. Beef flavor intensity was greater (P < 0.02) for AL and PM than MP. Off-flavor intensity was greater (P < 0.001) for all forage-fed steaks, regardless of forage species, than CON. Finishing on forages reduced (P = 0.003) total lipid content by 61% for the LM compared with CON finished cattle. Forage species grazed before harvest did not alter (P > 0.05) total lipid content of the LM. Oleic acid concentration and total MUFA of the LM were 21% and 22% less (P = 0.001) for FOR than CON. Concentrations of all individual [linolenic acid, eicosapentaenoic (EPA), docosapentaenoic (DPA), and docosadexaenoic (DHA) acids] and total n-3 fatty acids were greater (P < 0.001) for FOR than CON. Finishing on AL increased (P = 0.017) the concentration of linolenic acid compared with MP or PM. The ratio of n-6 to n-3 fatty acids was greater (P = 0.001) for CON than FOR and did not differ (P = 0.88) by forage species. Concentrate finishing increases carcass weight with same time endpoints and accelerates deposition of MUFA in comparison with FOR, which reduces carcass weight and fat deposition but maintains high concentrations of n-3 and CLA fatty acids. Finishing system or forage species grazed 40 d before slaughter did not alter beef tenderness but FOR had greater off-flavors according to both trained and descriptive sensory panelists.

Responses of nocturnal rodents to shrub encroachment in Banni grasslands, Gujarat, India

NASA Astrophysics Data System (ADS)

Jayadevan, A.

2016-12-01

Shrub encroachment is one of the greatest threats to grasslands globally. These woodlands can strongly influence the behaviour of small mammals adapted to more open habitats, which rely on high visibility for early detection of predators. In semi-arid grasslands, rodents are considered keystone species. Although shrub encroachment is known to negatively affect rodent assemblages, its impact on the foraging behaviour of rodents, which is known to vary in response to risky situations, is unknown. Understanding whether shrub encroachment alters such antipredator behaviour is important as antipredator behaviour can alter the distribution, abundance and ultimately, survival of prey species. In this study, I explored the effects of shrub encroachment on the foraging behaviour of nocturnal rodent communities in the Banni grasslands, India. I examined foraging behaviour, quantified using the giving-up density (GUD) framework and the number of rodent crossings around food patches, in two habitats that differed in the extent of shrub encroachment. Under the GUD framework, the amount of food left behind by a forager in a food patch reflects the costs of feeding at the patch. Higher GUDs imply higher foraging costs. I also investigated how removal of an invasive woody plant, Prosopis juliflora would affect foraging behaviour of nocturnal rodents. High shrub encroachment was associated with higher foraging costs (higher GUDs) and lower activity than the sparsely wooded habitat, likely due to low visibility in the densely wooded habitat. The dense habitat also supported a higher richness and relative abundance of generalist rodents than the sparse habitat, likely due to the increased heterogeneity of the habitat. The tree removal experiment revealed that rodents had lower GUDs (i.e., low foraging costs) after the event of tree cutting. This may be due to the reduction of cover in the habitat, leading to higher visibility and lower predation risk. My results suggest that shrub encroachment is associated with changes in both behaviour and species composition of rodents. Given that rodents play the role of ecosystem engineers in grasslands, these results underscore the need to conserve and restore the grasslands of Banni which are facing increasing encroachment by woodland species and are also subject to afforestation schemes.

Stable Isotope Tracking of Endangered Sea Turtles: Validation with Satellite Telemetry and δ15N Analysis of Amino Acids

PubMed Central

Seminoff, Jeffrey A.; Benson, Scott R.; Arthur, Karen E.; Eguchi, Tomoharu; Dutton, Peter H.; Tapilatu, Ricardo F.; Popp, Brian N.

2012-01-01

Effective conservation strategies for highly migratory species must incorporate information about long-distance movements and locations of high-use foraging areas. However, the inherent challenges of directly monitoring these factors call for creative research approaches and innovative application of existing tools. Highly migratory marine species, such as marine turtles, regularly travel hundreds or thousands of kilometers between breeding and feeding areas, but identification of migratory routes and habitat use patterns remains elusive. Here we use satellite telemetry in combination with compound-specific isotope analysis of amino acids to confirm that insights from bulk tissue stable isotope analysis can reveal divergent migratory strategies and within-population segregation of foraging groups of critically endangered leatherback sea turtles (Dermochelys coriacea) across the Pacific Ocean. Among the 78 turtles studied, we found a distinct dichotomy in δ15N values of bulk skin, with distinct “low δ15N” and “high δ15N” groups. δ15N analysis of amino acids confirmed that this disparity resulted from isotopic differences at the base of the food chain and not from differences in trophic position between the two groups. Satellite tracking of 13 individuals indicated that their bulk skin δ15N value was linked to the particular foraging region of each turtle. These findings confirm that prevailing marine isoscapes of foraging areas can be reflected in the isotopic compositions of marine turtle body tissues sampled at nesting beaches. We use a Bayesian mixture model to show that between 82 and 100% of the 78 skin-sampled turtles could be assigned with confidence to either the eastern Pacific or western Pacific, with 33 to 66% of all turtles foraging in the eastern Pacific. Our forensic approach validates the use of stable isotopes to depict leatherback turtle movements over broad spatial ranges and is timely for establishing wise conservation efforts in light of this species’ imminent risk of extinction in the Pacific. PMID:22666354

Stable isotope tracking of endangered sea turtles: validation with satellite telemetry and δ15N analysis of amino acids.

PubMed

Seminoff, Jeffrey A; Benson, Scott R; Arthur, Karen E; Eguchi, Tomoharu; Dutton, Peter H; Tapilatu, Ricardo F; Popp, Brian N

2012-01-01

Effective conservation strategies for highly migratory species must incorporate information about long-distance movements and locations of high-use foraging areas. However, the inherent challenges of directly monitoring these factors call for creative research approaches and innovative application of existing tools. Highly migratory marine species, such as marine turtles, regularly travel hundreds or thousands of kilometers between breeding and feeding areas, but identification of migratory routes and habitat use patterns remains elusive. Here we use satellite telemetry in combination with compound-specific isotope analysis of amino acids to confirm that insights from bulk tissue stable isotope analysis can reveal divergent migratory strategies and within-population segregation of foraging groups of critically endangered leatherback sea turtles (Dermochelys coriacea) across the Pacific Ocean. Among the 78 turtles studied, we found a distinct dichotomy in δ(15)N values of bulk skin, with distinct "low δ(15)N" and "high δ(15)N" groups. δ(15)N analysis of amino acids confirmed that this disparity resulted from isotopic differences at the base of the food chain and not from differences in trophic position between the two groups. Satellite tracking of 13 individuals indicated that their bulk skin δ(15)N value was linked to the particular foraging region of each turtle. These findings confirm that prevailing marine isoscapes of foraging areas can be reflected in the isotopic compositions of marine turtle body tissues sampled at nesting beaches. We use a Bayesian mixture model to show that between 82 and 100% of the 78 skin-sampled turtles could be assigned with confidence to either the eastern Pacific or western Pacific, with 33 to 66% of all turtles foraging in the eastern Pacific. Our forensic approach validates the use of stable isotopes to depict leatherback turtle movements over broad spatial ranges and is timely for establishing wise conservation efforts in light of this species' imminent risk of extinction in the Pacific.

Feeding-Related Traits Are Affected by Dosage of the foraging Gene in Drosophila melanogaster

PubMed Central

Allen, Aaron M.; Anreiter, Ina; Neville, Megan C.; Sokolowski, Marla B.

2017-01-01

Nutrient acquisition and energy storage are critical parts of achieving metabolic homeostasis. The foraging gene in Drosophila melanogaster has previously been implicated in multiple feeding-related and metabolic traits. Before foraging’s functions can be further dissected, we need a precise genetic null mutant to definitively map its amorphic phenotypes. We used homologous recombination to precisely delete foraging, generating the for0 null allele, and used recombineering to reintegrate a full copy of the gene, generating the {forBAC} rescue allele. We show that a total loss of foraging expression in larvae results in reduced larval path length and food intake behavior, while conversely showing an increase in triglyceride levels. Furthermore, varying foraging gene dosage demonstrates a linear dose-response on these phenotypes in relation to foraging gene expression levels. These experiments have unequivocally proven a causal, dose-dependent relationship between the foraging gene and its pleiotropic influence on these feeding-related traits. Our analysis of foraging’s transcription start sites, termination sites, and splicing patterns using rapid amplification of cDNA ends (RACE) and full-length cDNA sequencing, revealed four independent promoters, pr1–4, that produce 21 transcripts with nine distinct open reading frames (ORFs). The use of alternative promoters and alternative splicing at the foraging locus creates diversity and flexibility in the regulation of gene expression, and ultimately function. Future studies will exploit these genetic tools to precisely dissect the isoform- and tissue-specific requirements of foraging’s functions and shed light on the genetic control of feeding-related traits involved in energy homeostasis. PMID:28007892

Food searching behaviour of a Lepidoptera pest species is modulated by the foraging gene polymorphism.

PubMed

Chardonnet, Floriane; Capdevielle-Dulac, Claire; Chouquet, Bastien; Joly, Nicolas; Harry, Myriam; Le Ru, Bruno; Silvain, Jean-François; Kaiser, Laure

2014-10-01

The extent of damage to crop plants from pest insects depends on the foraging behaviour of the insect's feeding stage. Little is known, however, about the genetic and molecular bases of foraging behaviour in phytophagous pest insects. The foraging gene (for), a candidate gene encoding a PKG-I, has an evolutionarily conserved function in feeding strategies. Until now, for had never been studied in Lepidoptera, which includes major pest species. The cereal stem borer Sesamia nonagrioides is therefore a relevant species within this order with which to study conservation of and polymorphism in the for gene, and its role in foraging - a behavioural trait that is directly associated with plant injuries. Full sequencing of for cDNA in S. nonagrioides revealed a high degree of conservation with other insect taxa. Activation of PKG by a cGMP analogue increased larval foraging activity, measured by how frequently larvae moved between food patches in an actimeter. We found one non-synonymous allelic variation in a natural population that defined two allelic variants. These variants presented significantly different levels of foraging activity, and the behaviour was positively correlated to gene expression levels. Our results show that for gene function is conserved in this species of Lepidoptera, and describe an original case of a single nucleotide polymorphism associated with foraging behaviour variation in a pest insect. By illustrating how variation in this single gene can predict phenotype, this work opens new perspectives into the evolutionary context of insect adaptation to plants, as well as pest management. © 2014. Published by The Company of Biologists Ltd.

The Role of Natural Enemy Foraging Guilds in Controlling Cereal Aphids in Michigan Wheat

PubMed Central

Safarzoda, Shahlo; Bahlai, Christine A.; Fox, Aaron F.; Landis, Douglas A.

2014-01-01

Insect natural enemies (predators and parasitoids) provide important ecosystem services by suppressing populations of insect pests in many agricultural crops. However, the role of natural enemies against cereal aphids in Michigan winter wheat (Triticum aestivum L.) is largely unknown. The objectives of this research were to characterize the natural enemy community in wheat fields and evaluate the role of different natural enemy foraging guilds (foliar-foraging versus ground-dwelling predators) in regulating cereal aphid population growth. We investigated these objectives during the spring and summer of 2012 and 2013 in four winter wheat fields on the Michigan State University campus farm in East Lansing, Michigan. We monitored and measured the impact of natural enemies by experimentally excluding or allowing their access to wheat plants infested with Rhopalosiphum padi (L.) and Sitobion avenae (F.) (Hemiptera: Aphidae). Our results indicate that the natural enemy community in the wheat fields consisted mostly of foliar-foraging and ground-dwelling predators with relatively few parasitoids. In combination, these natural enemy groups were very effective at reducing cereal aphid populations. We also investigated the role of each natural enemy foraging guild (foliar-foraging versus ground-dwelling predators) independently. Overall, our results suggest that, in combination, natural enemies can almost completely halt early-season aphid population increase. Independently, ground-dwelling predators were more effective at suppressing cereal aphid populations than foliar-foraging predators under the conditions we studied. Our results differ from studies in Europe and the US Great Plains where foliar foraging predators and parasitoids are frequently more important cereal aphid natural enemies. PMID:25473951

Evaluation of radio-tracking and strip transect methods for determining foraging ranges of Black-Legged Kittiwakes

USGS Publications Warehouse

Ostrand, William D.; Drew, G.S.; Suryan, R.M.; McDonald, L.L.

1998-01-01

We compared strip transect and radio-tracking methods of determining foraging range of Black-legged Kittiwakes (Rissa tridactyla). The mean distance birds were observed from their colony determined by radio-tracking was significantly greater than the mean value calculated from strip transects. We determined that this difference was due to two sources of bias: (1) as distance from the colony increased, the area of available habitat also increased resulting in decreasing bird densities (bird spreading). Consequently, the probability of detecting birds during transect surveys also would decrease as distance from the colony increased, and (2) the maximum distance birds were observed from the colony during radio-tracking exceeded the extent of the strip transect survey. We compared the observed number of birds seen on the strip transect survey to the predictions of a model of the decreasing probability of detection due to bird spreading. Strip transect data were significantly different from modeled data; however, the field data were consistently equal to or below the model predictions, indicating a general conformity to the concept of declining detection at increasing distance. We conclude that radio-tracking data gave a more representative indication of foraging distances than did strip transect sampling. Previous studies of seabirds that have used strip transect sampling without accounting for bird spreading or the effects of study-area limitations probably underestimated foraging range.

Digesting or swimming? Integration of the postprandial metabolism, behavior and locomotion in a frequently foraging fish.

PubMed

Nie, Li-Juan; Cao, Zhen-Dong; Fu, Shi-Jian

2017-02-01

Fish that are active foragers usually perform routine activities while digesting their food; thus, their postprandial swimming capacity and related behavior adjustments might be ecologically important. To test whether digestion affect swimming performance and the relationships of digestion with metabolism and behavior in an active forager, we investigated the postprandial metabolic response, spontaneous swimming activities, critical swimming speed (Ucrit), and fast-start escape performance of both fasted and digesting (3h after feeding to satiation) juvenile rose bitterling (Rhodeus ocellatus). Feeding to satiation elicited a 50% increase in the oxygen consumption rate, which peaked at 3h after feeding and returned to the prefeeding state after another 3h. However, approximately 50% and 90% of individuals resumed feeding behavior at 2 and 3h postfeeding, respectively, although the meal size varied substantially. Digestion showed no effect on either steady swimming performance as suggested by the Ucrit or unsteady swimming performance indicated by the maximum linear velocity in fast-start escape movement. However, digesting fish showed more spontaneous activity as indicated by the longer total distance traveled, mainly through an increased percentage of time spent moving (PTM). A further analysis found that fasting individuals with high swimming speed were more inclined to increase their PTM during digestive processes. The present study suggests that as an active forager With a small meal size and hence limited postprandial physiological and morphological changes, the swimming performance of rose bitterling is maintained during digestion, which might be crucial for its active foraging mode and anti-predation strategy. Copyright © 2016 Elsevier Inc. All rights reserved.

Foraging decisions of bison for rapid energy gains can explain the relative risk to neighboring plants in complex swards.

PubMed

Courant, Sabrina; Fortin, Daniel

2010-06-01

Herbivores commonly base their foraging decisions not only on the intrinsic characteristics of plants, but also on the attributes of neighboring species. Although herbivores commonly orient their food choices toward the maximization of energy intake, the impact of such choices on neighboring plants remains largely unexplored. We evaluated whether foraging decisions by herbivores aiming at a rapid intake of digestible energy could explain multiple neighboring effects in complex swards. Specifically, we assessed how spatial patterns of occurrence of Carex atherodes, a highly profitable sedge species, could control the risk of bison (Bison bison) herbivory for seven other plant species. The foraging behavior of 70 free-ranging bison was evaluated in their natural environment during summer, and then related to plant characteristics. We used this information to estimate the instantaneous intake rate of digestible energy at individual feeding stations. We found that neighbor contrast defense and associational susceptibility can both be explained by simple foraging rules of energy maximization. Energy gains were higher when C. atherodes was consumed while avoiding the species for which we detected neighbor contrast defense. The lower intake rate associated with their consumption was due to an increase in handling time caused by their small size relative to C. atherodes. Bison also had higher energy gains by consuming instead of avoiding the plant species that experienced associational susceptibility. Because most of these plants were at least as tall as C. atherodes, their presence increased the heterogeneity of the grazed stratum. Avoiding their consumption increased handling time thereby reducing the instantaneous rate of energy intake. Overall, we found that bison adjust their fine-scale foraging decisions to vertical and horizontal sward structures in a way that maximizes their energy intake rate. Energy maximization principles thus provide a valuable framework to evaluate a broad-range of neighboring effects for prey faced with generalist consumers.

The ontogeny of immunity: development of innate immune strength in the honey bee (Apis mellifera).

PubMed

Wilson-Rich, Noah; Dres, Stephanie T; Starks, Philip T

2008-01-01

Honey bees (Apis mellifera) are of vital economic and ecological importance. These eusocial animals display temporal polyethism, which is an age-driven division of labor. Younger adult bees remain in the hive and tend to developing brood, while older adult bees forage for pollen and nectar to feed the colony. As honey bees mature, the types of pathogens they experience also change. As such, pathogen pressure may affect bees differently throughout their lifespan. We provide the first direct tests of honey bee innate immune strength across developmental stages. We investigated immune strength across four developmental stages: larvae, pupae, nurses (1-day-old adults), and foragers (22-30 days old adults). The immune strength of honey bees was quantified using standard immunocompetence assays: total hemocyte count, encapsulation response, fat body quantification, and phenoloxidase activity. Larvae and pupae had the highest total hemocyte counts, while there was no difference in encapsulation response between developmental stages. Nurses had more fat body mass than foragers, while phenoloxidase activity increased directly with honey bee development. Immune strength was most vigorous in older, foraging bees and weakest in young bees. Importantly, we found that adult honey bees do not abandon cellular immunocompetence as has recently been proposed. Induced shifts in behavioral roles may increase a colony's susceptibility to disease if nurses begin foraging activity prematurely.

Integrating diverse forage sources reduces feed gaps on mixed crop-livestock farms.

PubMed

Bell, L W; Moore, A D; Thomas, D T

2017-12-04

Highly variable climates induce large variability in the supply of forage for livestock and so farmers must manage their livestock systems to reduce the risk of feed gaps (i.e. periods when livestock feed demand exceeds forage supply). However, mixed crop-livestock farmers can utilise a range of feed sources on their farms to help mitigate these risks. This paper reports on the development and application of a simple whole-farm feed-energy balance calculator which is used to evaluate the frequency and magnitude of feed gaps. The calculator matches long-term simulations of variation in forage and metabolisable energy supply from diverse sources against energy demand for different livestock enterprises. Scenarios of increasing the diversity of forage sources in livestock systems is investigated for six locations selected to span Australia's crop-livestock zone. We found that systems relying on only one feed source were prone to higher risk of feed gaps, and hence, would often have to reduce stocking rates to mitigate these risks or use supplementary feed. At all sites, by adding more feed sources to the farm feedbase the continuity of supply of both fresh and carry-over forage was improved, reducing the frequency and magnitude of feed deficits. However, there were diminishing returns from making the feedbase more complex, with combinations of two to three feed sources typically achieving the maximum benefits in terms of reducing the risk of feed gaps. Higher stocking rates could be maintained while limiting risk when combinations of other feed sources were introduced into the feedbase. For the same level of risk, a feedbase relying on a diversity of forage sources could support stocking rates 1.4 to 3 times higher than if they were using a single pasture source. This suggests that there is significant capacity to mitigate both risk of feed gaps at the same time as increasing 'safe' stocking rates through better integration of feed sources on mixed crop-livestock farms across diverse regions and climates.

Linking foraging behaviour to physical oceanographic structures: Southern elephant seals and mesoscale eddies east of Kerguelen Islands

NASA Astrophysics Data System (ADS)

Dragon, Anne-Cecile; Monestiez, P.; Bar-Hen, A.; Guinet, C.

2010-10-01

In the Southern Ocean, mesoscale features, such as fronts and eddies, have been shown to have a significant impact in structuring and enhancing primary productivity. They are therefore likely to influence the spatial structure of prey fields and play a key role in the creation of preferred foraging regions for oceanic top-predators. Optimal foraging theory predicts that predators should adjust their movement behaviour in relation to prey density. While crossing areas with sufficient prey density, we expect predators would change their behaviour by, for instance, decreasing their speed and increasing their turning frequency. Diving predators would as well increase the useful part of their dive i.e. increase bottom-time thereby increasing the fraction of time spent capturing prey. Southern elephant seals from the Kerguelen population have several foraging areas: in Antarctic waters, on the Kerguelen Plateau and in the interfrontal zone between the Subtropical and Polar Fronts. This study investigated how the movement and diving behaviour of 22 seals equipped with satellite-relayed data loggers changed in relation to mesoscale structures typical of the interfrontal zone. We studied the links between oceanographic variables including temperature and sea level anomalies, and diving and movement behaviour such as displacement speed, diving duration and bottom-time. Correlation coefficients between each of the time series were calculated and their significance tested with a parametric bootstrap. We focused on oceanographic changes, both temporal and spatial, occurring during behavioural transitions in order to clarify the connections between the behaviour and the marine environment of the animals. We showed that a majority of seals displayed a specific foraging behaviour related to the presence of both cyclonic and anticyclonic eddies. We characterized mesoscale oceanographic zones as either favourable or unfavourable based on the intensity of foraging activity as identified by the behavioural variables. Our findings highlight the importance of mesoscale features for top-predators’ behaviour and introduce a new approach for evaluating the importance to the seals of the origin and intensity of these features.

Pheromone-modulated behavioral suites influence colony growth in the honey bee (Apis mellifera)

NASA Astrophysics Data System (ADS)

Pankiw, Tanya; Roman, Roman; Sagili, Ramesh R.; Zhu-Salzman, Keyan

2004-12-01

The success of a species depends on its ability to assess its environment and to decide accordingly which behaviors are most appropriate. Many animal species, from bacteria to mammals, are able to communicate using interspecies chemicals called pheromones. In addition to exerting physiological effects on individuals, for social species, pheromones communicate group social structure. Communication of social structure is important to social insects for the allocation of its working members into coordinated suites of behaviors. We tested effects of long-term treatment with brood pheromone on suites of honey bee brood rearing and foraging behaviors. Pheromone-treated colonies reared significantly greater brood areas and more adults than controls, while amounts of stored pollen and honey remained statistically similar. Brood pheromone increased the number of pollen foragers and the pollen load weights they returned. It appeared that the pheromone-induced increase in pollen intake was directly canalized into more brood rearing. A two-way pheromone priming effect was observed, such that some workers from the same age cohorts showed an increased and extended capacity to rear larvae, while others were recruited at significantly younger ages into pollen-specific foraging. Brood pheromone affected suites of nursing and foraging behaviors allocating worker and pollen resources associated with an important fitness trait, colony growth.

Foraging in an unsteady world: bumblebee flight performance in field-realistic turbulence

PubMed Central

Chang, J. J.; Oppenheimer, R. L.; Combes, S. A.

2017-01-01

Natural environments are characterized by variable wind that can pose significant challenges for flying animals and robots. However, our understanding of the flow conditions that animals experience outdoors and how these impact flight performance remains limited. Here, we combine laboratory and field experiments to characterize wind conditions encountered by foraging bumblebees in outdoor environments and test the effects of these conditions on flight. We used radio-frequency tags to track foraging activity of uniquely identified bumblebee (Bombus impatiens) workers, while simultaneously recording local wind flows. Despite being subjected to a wide range of speeds and turbulence intensities, we find that bees do not avoid foraging in windy conditions. We then examined the impacts of turbulence on bumblebee flight in a wind tunnel. Rolling instabilities increased in turbulence, but only at higher wind speeds. Bees displayed higher mean wingbeat frequency and stroke amplitude in these conditions, as well as increased asymmetry in stroke amplitude—suggesting that bees employ an array of active responses to enable flight in turbulence, which may increase the energetic cost of flight. Our results provide the first direct evidence that moderate, environmentally relevant turbulence affects insect flight performance, and suggest that flying insects use diverse mechanisms to cope with these instabilities. PMID:28163878

Foraging in an unsteady world: bumblebee flight performance in field-realistic turbulence.

PubMed

Crall, J D; Chang, J J; Oppenheimer, R L; Combes, S A

2017-02-06

Natural environments are characterized by variable wind that can pose significant challenges for flying animals and robots. However, our understanding of the flow conditions that animals experience outdoors and how these impact flight performance remains limited. Here, we combine laboratory and field experiments to characterize wind conditions encountered by foraging bumblebees in outdoor environments and test the effects of these conditions on flight. We used radio-frequency tags to track foraging activity of uniquely identified bumblebee ( Bombus impatiens ) workers, while simultaneously recording local wind flows. Despite being subjected to a wide range of speeds and turbulence intensities, we find that bees do not avoid foraging in windy conditions. We then examined the impacts of turbulence on bumblebee flight in a wind tunnel. Rolling instabilities increased in turbulence, but only at higher wind speeds. Bees displayed higher mean wingbeat frequency and stroke amplitude in these conditions, as well as increased asymmetry in stroke amplitude-suggesting that bees employ an array of active responses to enable flight in turbulence, which may increase the energetic cost of flight. Our results provide the first direct evidence that moderate, environmentally relevant turbulence affects insect flight performance, and suggest that flying insects use diverse mechanisms to cope with these instabilities.

Short-term foraging costs and long-term fueling rates in central-place foraging swans revealed by giving-up exploitation times.

PubMed

van Gils, J A; Tijsen, W

2007-05-01

Foragers tend to exploit patches to a lesser extent farther away from their central place. This has been interpreted as a response to increased risk of predation or increased metabolic costs of prey delivery. Here we show that migratory Bewick's swans (Cygnus columbianus bewickii), though not incurring greater predation risks farther out or delivering food to a central place, also feed for shorter periods at patches farther away from their roost. Predictions from an energy budget model suggest that increasing metabolic travel costs per se are responsible. Establishing the relation between intake rate and exploitation time enabled us to express giving-up exploitation times as quitting harvest rates (QHRs). This revealed that net QHRs were not different from observed long-term net intake rates, a sign that the birds were maximizing their long-term net intake rate. This study is unique because giving-up decisions were measured at the individual level, metabolic and predation costs were assessed simultaneously, the relation with harvest rate was made explicit, and finally, short-term giving-up decisions were related to long-term net intake rates. We discuss and conceptualize the implications of metabolic traveling costs for carrying-capacity predictions by bridging the gap between optimal-foraging theory and optimal-migration theory.

Seasonal foraging patterns of forest-grazing Japanese Black heifers with increased plasma total antioxidant capacity.

PubMed

Haga, Satoshi; Nakano, Miwa; Nakao, Seiji; Hirano, Kiyoshi; Yamamoto, Yoshito; Sasaki, Hiroyuki; Ishizaki, Hiroshi

2016-02-01

Forest-grazing enables the intake of high total antioxidant capacity (TAC) plants that might be beneficial for the TAC status of cattle. This study evaluated the relation between the seasonal foraging patterns of forest-grazing Japanese Black (JB) heifers or the TAC levels in shrubs and trees and the changes of plasma TAC. We examined 12 JB heifers, four each of which were allocated to forest-grazing (F), pasture-grazing, and pen-housed groups. The plasma TAC level in F heifers on July 26, August 13, 30 and September 17 were significantly higher than those on April 27 and June 4 (P < 0.05). In F group, the mean rates of foraging frequency (FF) of shrubs and trees during July 5-8 and September 13-16 were much higher than that during May 31-June 3 (P < 0.05). The rate of FF of grass significantly decreased later in the season (P < 0.05). The mean TAC levels in these shrubs and trees were higher than those in grasses, concentrates, and timothy hay. Results suggest that an important factor in the increase of plasma TAC in forest-grazing cattle might be the increased foraging of TAC-rich shrubs and trees during summer-fall. © 2015 Japanese Society of Animal Science.

Pheromone-modulated behavioral suites influence colony growth in the honey bee (Apis mellifera).

PubMed

Pankiw, Tanya; Roman, Roman; Sagili, Ramesh R; Zhu-Salzman, Keyan

2004-12-01

The success of a species depends on its ability to assess its environment and to decide accordingly which behaviors are most appropriate. Many animal species, from bacteria to mammals, are able to communicate using interspecies chemicals called pheromones. In addition to exerting physiological effects on individuals, for social species, pheromones communicate group social structure. Communication of social structure is important to social insects for the allocation of its working members into coordinated suites of behaviors. We tested effects of long-term treatment with brood pheromone on suites of honey bee brood rearing and foraging behaviors. Pheromone-treated colonies reared significantly greater brood areas and more adults than controls, while amounts of stored pollen and honey remained statistically similar. Brood pheromone increased the number of pollen foragers and the pollen load weights they returned. It appeared that the pheromone-induced increase in pollen intake was directly canalized into more brood rearing. A two-way pheromone priming effect was observed, such that some workers from the same age cohorts showed an increased and extended capacity to rear larvae, while others were recruited at significantly younger ages into pollen-specific foraging. Brood pheromone affected suites of nursing and foraging behaviors allocating worker and pollen resources associated with an important fitness trait, colony growth.

Behavioral and physiological responses to subgroup size and number of people in howler monkeys inhabiting a forest fragment used for nature-based tourism.

PubMed

Aguilar-Melo, Adriana R; Andresen, Ellen; Cristóbal-Azkarate, Jurgi; Arroyo-Rodríguez, Victor; Chavira, Roberto; Schondube, Jorge; Serio-Silva, Juan Carlos; Cuarón, Alfredo D

2013-11-01

Animals' responses to potentially threatening factors can provide important information for their conservation. Group size and human presence are potentially threatening factors to primates inhabiting small reserves used for recreation. We tested these hypotheses by evaluating behavioral and physiological responses in two groups of mantled howler monkeys (Alouatta palliata mexicana) at the "Centro Ecológico y Recreativo El Zapotal", a recreational forest reserve and zoo located in the Mexican state of Chiapas. Both groups presented fission-fusion dynamics, splitting into foraging subgroups which varied in size among, but not within days. Neither subgroup size nor number of people had an effect on fecal cortisol. Out of 16 behavioral response variables tested, the studied factors had effects on six: four were affected by subgroup size and two were affected by number of people. With increasing subgroup size, monkeys increased daily path lengths, rested less, increased foraging effort, and used more plant individuals for feeding. As the number of people increased, monkeys spent more time in lower-quality habitat, and less time engaged in social interactions. Although fecal cortisol levels were not affected by the factors studied, one of the monkey groups had almost twice the level of cortisol compared to the other group. The group with higher cortisol levels also spent significantly more time in the lower-quality habitat, compared to the other group. Our results suggest that particular behavioral adjustments might allow howler monkeys at El Zapotal to avoid physiological stress due to subgroup size and number of people. However, the fact that one of the monkey groups is showing increased cortisol levels may be interpreted as a warning sign, indicating that an adjustment threshold is being reached, at least for part of the howler monkey population in this forest fragment. © 2013 Wiley Periodicals, Inc.

Effects of N loading rate on CH4 and N2O emissions during cultivation and fallow periods from forage rice fields fertilized with liquid cattle waste.

PubMed

Riya, S; Zhou, S; Kobara, Y; Sagehashi, M; Terada, A; Hosomi, M

2015-09-15

The use of liquid cattle waste (LCW) as a fertilizer for forage rice is important for material recycling because it can promote biomass production, and reduce the use of chemical fertilizer. Meanwhile, increase in emission of greenhouse gases (GHGs), especially CH4 and N2O would be concerned. We conducted a field study to determine the optimum loading rate of LCW as N to promote forage rice growth with lower GHG emissions. The LCW was applied to forage rice fields, N100, N250, N500, and N750, at four different N loading rates of 107, 258, 522, and 786 kg N ha(-1), respectively, including 50 kg N ha(-1) of basal chemical fertilizer. The above-ground biomass yields increased 14.6-18.5 t ha(-1) with increases in N loading rates. During the cultivation period, both the CH4 and N2O fluxes increased with increases in LCW loading rates. In the treatments of N100, N250, N500, and N750, the cumulative CH4 emissions during the entire period, including cultivation and fallow period were 29.6, 18.1, 54.4, and 67.5 kg C ha(-1), respectively, whereas those of N2O were -0.15, -0.02, 1.49, and 5.82 kg N ha(-1), respectively. Considering the greenhouse gas emissions and above-ground biomass, the yield-scaled CO2-equivalents (CO2-eqs) were 66.3, 35.9, 161, and 272 kg CO2 t(-1) for N100, N250, N500, and N750, respectively. These results suggest that N250 is the most appropriate LCW loading rate for promoting forage rice production with lower GHG emissions. Copyright © 2015 Elsevier Ltd. All rights reserved.

Influence of dietary forage and feed intake on carbohydrase activities and small intestinal morphology of calves.

PubMed

Kreikemeier, K K; Harmon, D L; Peters, J P; Gross, K L; Armendariz, C K; Krehbiel, C R

1990-09-01

Twenty (12 Holstein, 8 Longhorn cross) calves (198 kg and 7 mo old) were used in a randomized complete block design to evaluate the effects of dietary forage concentration and feed intake on carbohydrase activities and small intestinal (SI) morphology. Calves were individually fed 90% forage (alfalfa) or a 90% concentrate (50% sorghum: 50% wheat) diet at either one or two times NEm for 140 d and slaughtered; tissues and small intestinal digesta were collected. Increased feed intake increased (P less than .05) pancreatic weight, alpha-amylase and glucoamylase activities in the pancreas, SI length and SI digesta weight. Forage-fed calves gained faster (P less than .01) and had greater (P less than .05) pancreatic protein concentrations, alpha-amylase and glucoamylase activities in the pancreas and greater SI digesta alpha-amylase activities than grain-fed calves did. Increased feed intake increased (P less than .01) mucosal weight/cm small intestine only in forage-fed calves and increased (P less than .05) SI surface/volume only in grain-fed calves. Mucosal weight was greatest (P less than .05) at the terminal ileum, surface/volume was greatest (P less than .05) in the duodenum, and mucosal protein concentration was highest (P less than .05) in the SI mid-section. Mucosal lactase was higher (P less than .05) in proximal segments, whereas mucosal isomaltase was higher in middle and distal segments of the small intestine. For mucosal maltase activity, there was a feed intake x SI sampling site interaction (P less than .05) and for trehalase, a diet x feed intake x SI sampling site interaction (P less than .05). The SI distribution patterns of maltase and isomaltase were similar, as were those of trehalase and lactase. The alpha-amylase activity in the pancreas and SI morphology were influenced greatly by diet composition and feed intake by calves.

A perspective on forage production in Canada.

PubMed

Gareau, L

1980-03-01

Over the past decade, the cattle industry has experienced practically a full circle. With the promising beef prices in the early 1970s, with the glut of grain and a generous assist from government incentive programs, the forage acreage and cattle population have increased at a record rate. By 1974, the tide began to turn - grain prices went up sharply and beef prices became sluggish - and by 1976 a major crisis faced the producers. The cattle industry which had been developing on a cheap grain economy was now obliged to rely more on forage for its survival. Unfortunately, the forage was not existent and the only salvation of the industry was the gift of Providence - weather patterns that provided ample moisture conditions and above normal forage crops, the utilization of cereals and the intervention of government cow-calf support programs. Over the past year, the cycle was completed and record beef prices again prevail. The barley bins are full again and the cattlemen are gearing up for a few fat years. Demands for forage seed are brisk and the seeding down of forage acreage is bound to increase substantially over the next few years. And with this increase, cattle population expansion is bound to follow: how much expansion can the economy support? The production cost factors will determine the extent, but one can almost be certain that any expansion will either be modest or of short duration. At least, it should be. If the cattle industry is to establish solid foundations, it cannot be dependent upon the instability of a grain surplus-shortage position. With the present resources and the potential for developing it in direct competition with other crops, one can only expect a small and steady expansion over a long time span. One must agree with the range researchers and specialists of the Canada Research Stations at Lethbridge and Swift Current that pasture and range will continue to be the limiting factors of cattle expansion as they have been for the past 50 years. It is interesting to note that in the Prairie Provinces at least, the number of livestock raised each year has not changed since 1930 although cattle have largely replaced the horses. It is easy to speculate on paper that Canada can double in the next 20 years its forage and cattle production on its large expanses of land on the fringes of the agriculturally settled areas. It is true that these lands, while marginal for cash crops, could produce excellent forage. But at what cost? And what kind of pasture could we grow on them?It is easy to speculate that our livestock geneticists can breed a ruminant-type animal that will feed on poplar saplings and poplar leaves, or develop a new breed of cattle with buffalo vigor that will thrive in the extreme north. But looking at the musk-ox experience in the Northwest Territories and the history of the Wood Buffalo National Park leaves little room for optimism. The present generation is not likely to see in its lifetime the cattle population go beyond the 20 million mark. We can look, however, with good assurance on the present cattle numbers remaining stable and can look forward to gradual increase brought about by normal improvement in both forage and cattle management.Hopefully, both the cattle producer and the veterinarian will be able to reap the benefits of this most important segment of Canada's agricultural industry.