Construction patterns of birds' nests provide insight into nest-building behaviours.

PubMed

Biddle, Lucia; Goodman, Adrian M; Deeming, D Charles

2017-01-01

Previous studies have suggested that birds and mammals select materials needed for nest building based on their thermal or structural properties, although the amounts or properties of the materials used have been recorded for only a very small number of species. Some of the behaviours underlying the construction of nests can be indirectly determined by careful deconstruction of the structure and measurement of the biomechanical properties of the materials used. Here we examined this idea in an investigation of Bullfinch ( Pyrrhula pyrrhula ) nests as a model for open-nesting songbird species that construct a "twig" nest, and tested the hypothesis that materials in different parts of nests serve different functions. The quantities of materials present in the nest base, sides and cup were recorded before structural analysis. Structural analysis showed that the base of the outer nests were composed of significantly thicker, stronger and more rigid materials compared to the side walls, which in turn were significantly thicker, stronger and more rigid than materials used in the cup. These results suggest that the placement of particular materials in nests may not be random, but further work is required to determine if the final structure of a nest accurately reflects the construction process.

Waterfowl productivity and use of nesting structures in the prairie pothole region

USGS Publications Warehouse

Johnson, Rex R.; Higgins, Kenneth F.; Ball, I.J.; Kohn, Stan C.

1994-01-01

Over-water duck nests are usually more successful than upland nests. We evaluated mallard (Anas platyrhynchos) and giant Canada goose (Branta canadensis maxima) use of nest baskets, straw and hay bales, and earth-filled culverts and determined nesting success rates by structure type during 1987-1989. Mallards used bales and culverts more than baskets, whereas Canada geese used baskets more than bales or culverts. Nesting success was greatest for baskets and culverts (>80%) and lowest for bales (58.3%). Logistics aside, culverts appear to be the most valuable nesting structures for mallards, and baskets are the most valuable structures for Canada geese.

Importance of structural stability to success of mourning dove nests

USGS Publications Warehouse

Coon, R.A.; Nichols, J.D.; Percival, H.F.

1981-01-01

Studies of nest-site selection and nesting habitats often involve a "characterization" of nests and of habitats in which nests are found. Our objective in the present work is to identify nest-site characteristics that are associated with variation in components of Mourning Dove (Zenaida macroura) fitness (e.g. the probability of a nest succeeding), as opposed to simply "characterizing" dove nest sites. If certain nest- site characteristics affect the probability that a nest will succeed, then we suspect that these characteristics will be associated with either concealment (the probability of detection by certain predators) or structural stability (the probability of eggs or entire nests falling to the ground as a result of wind, rain storms, parental activity, etc.). Although other workers agree that structural stability is an important determinant of Mourning Dove nesting success (e.g. McClure 1944: 384; Woolfenden and Rohwer 1969: 59), we are aware of no actual tests of this hypothesis.

[Structure characteristics of natural nests and its implication to artificial nest frame design for Ciconia boyciana].

PubMed

Wei, Yi-qing; Cui, Guo-fa

2014-12-01

Artificial nest can improve the breeding success of birds in the field, and it has been proved to be more effective to endangered species. We surveyed the structure characteristics of natural nest and the status of the use of artificial nests for oriental white stork, Ciconia boyciana, in Honghe National Nature Reserve, Heilongjiang Province. Differences were investigated among the structure characteristics of the used and unused artificial nests, and natural nests based on one-way ANOVA. It was observed that significant differences in the diameter of nest branch, the vertical an- gle between nest branch, the height of the jointthe height of the nest above ground exited in different nest types. On account of the structure characteristics of the natural nests of C. boyciana, the suitable diameter of nest pillar for artificial nest frame should be 15.0-25.0 cm with the height of 5.0-12.0 m, which would be better if they were constructed by some acid-resistant materials, e.g., cement. The number of nest stands should be 3-4 individuals with the diameter of 9.0-12.0 cm, the vertical angle of 45 degrees-60 degrees, and the length of 90.0-140.0 cm.

Construction patterns of birds’ nests provide insight into nest-building behaviours

PubMed Central

Goodman, Adrian M.

2017-01-01

Previous studies have suggested that birds and mammals select materials needed for nest building based on their thermal or structural properties, although the amounts or properties of the materials used have been recorded for only a very small number of species. Some of the behaviours underlying the construction of nests can be indirectly determined by careful deconstruction of the structure and measurement of the biomechanical properties of the materials used. Here we examined this idea in an investigation of Bullfinch (Pyrrhula pyrrhula) nests as a model for open-nesting songbird species that construct a “twig” nest, and tested the hypothesis that materials in different parts of nests serve different functions. The quantities of materials present in the nest base, sides and cup were recorded before structural analysis. Structural analysis showed that the base of the outer nests were composed of significantly thicker, stronger and more rigid materials compared to the side walls, which in turn were significantly thicker, stronger and more rigid than materials used in the cup. These results suggest that the placement of particular materials in nests may not be random, but further work is required to determine if the final structure of a nest accurately reflects the construction process. PMID:28265501

The Impact of Ignoring the Level of Nesting Structure in Nonparametric Multilevel Latent Class Models

ERIC Educational Resources Information Center

Park, Jungkyu; Yu, Hsiu-Ting

2016-01-01

The multilevel latent class model (MLCM) is a multilevel extension of a latent class model (LCM) that is used to analyze nested structure data structure. The nonparametric version of an MLCM assumes a discrete latent variable at a higher-level nesting structure to account for the dependency among observations nested within a higher-level unit. In…

Methods for excluding cliff swallows from nesting on highway structures.

DOT National Transportation Integrated Search

2009-08-01

Cliff swallows (Petrochelidon pyrrhonota) are colonially breeding migratory birds that frequently nest on highway : structures. Protected by the Migratory Bird Treaty Act of 1918, nesting control methods cannot harm swallows or active : nests. This c...

Canada goose nest survival at rural wetlands in north-central Iowa

USGS Publications Warehouse

Ness, Brenna N.; Klaver, Robert W.

2016-01-01

The last comprehensive nest survival study of the breeding giant Canada goose (Branta canadensis maxima) population in Iowa, USA, was conducted >30 years ago during a period of population recovery, during which available nesting habitat consisted primarily of artificial nest structures. Currently, Iowa's resident goose population is stable and nests in a variety of habitats. We analyzed the effects of available habitat on nest survival and how nest survival rates compared with those of the expanding goose population studied previously to better understand how to maintain a sustainable Canada goose population in Iowa. We documented Canada goose nest survival at rural wetland sites in north-central Iowa. We monitored 121 nests in 2013 and 149 nests in 2014 at 5 Wildlife Management Areas (WMAs) with various nesting habitats, including islands, muskrat (Ondatra zibethicus) houses, and elevated nest structures. We estimated daily nest-survival rate using the nest survival model in Program MARK. Survival was influenced by year, site, stage, presence of a camera, nest age, and an interaction between nest age and stage. Nest success rates for the 28-day incubation period by site and year combination ranged from 0.10 to 0.84. Nest survival was greatest at sites with nest structures (β = 17.34). Nest survival was negatively affected by lowered water levels at Rice Lake WMA (2013 β = −0.77, nest age β = −0.07). Timing of water-level drawdowns for shallow lake restorations may influence nest survival rates.

Can hedgerow management mitigate the impacts of predation on songbird nest survival?

PubMed

Dunn, Jenny C; Gruar, Derek; Stoate, Chris; Szczur, John; Peach, Will J

2016-12-15

Nest predators can have significant impacts on songbird reproductive success. These impacts may be amplified by habitat simplification and here we test whether sympathetic management of farmland hedgerows can reduce nest depredation, especially by corvids. We test whether songbirds select nest sites according to structural features of hedgerows (including nest visibility and accessibility), and whether these features influence nest predation risk. Songbirds selected nesting sites affording higher vegetation cover above the nest, increased visibility on the nest-side of the hedgerow and reduced visibility on the far side of the hedge. Nest survival was unrelated to corvid abundance and only weakly related (at the egg stage) to corvid nest proximity. Nest survival at the chick stage was higher where vegetation structure restricted access to corvid-sized predators (averaging 0.78 vs. 0.53), and at nests close to potential vantage points. Overall nest survival was sensitive to hedgerow structure (accessibility) particularly at low exposure to corvid predation, while the overall impact of corvid exposure was dependent on the relationship involving proximity to vantage points. Nest survival over the chick stage was much higher (0.67) in stock-proof, trimmed and mechanically cut hedgerows, (which tended to provide lower side visibility and accessibility) than in recently laid, remnant or leggy hedgerows (0.18). Long-term reductions in the management of British hedgerows may therefore be exposing nesting songbirds to increased predation risk. We recommend regular rotational cutting of hedgerows to maintain a dense woody structure and thereby reduce songbird nest predation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Variability in vegetation effects on density and nesting success of grassland birds

USGS Publications Warehouse

Winter, Maiken; Johnson, Douglas H.; Shaffer, Jill A.

2005-01-01

The structure of vegetation in grassland systems, unlike that in forest systems, varies dramatically among years on the same sites, and among regions with similar vegetation. The role of this variation in vegetation structure on bird density and nesting success of grassland birds is poorly understood, primarily because few studies have included sufficiently large temporal and spatial scales to capture the variation in vegetation structure, bird density, or nesting success. To date, no large-scale study on grassland birds has been conducted to investigate whether grassland bird density and nesting success respond similarly to changes in vegetation structure. However, reliable management recommendations require investigations into the distribution and nesting success of grassland birds over larger temporal and spatial scales. In addition, studies need to examine whether bird density and nesting success respond similarly to changing environmental conditions. We investigated the effect of vegetation structure on the density and nesting success of 3 grassland-nesting birds: clay-colored sparrow (Spizella pallida), Savannah sparrow (Passerculus sandwichensis), and bobolink (Dolichonyx oryzivorus) in 3 regions of the northern tallgrass prairie in 1998-2001. Few vegetation features influenced the densities of our study species, and each species responded differently to those vegetation variables. We could identify only 1 variable that clearly influenced nesting success of 1 species: clay-colored sparrow nesting success increased with increasing percentage of nest cover from the surrounding vegetation. Because responses of avian density and nesting success to vegetation measures varied among regions, years, and species, land managers at all times need to provide grasslands with different types of vegetation structure. Management guidelines developed from small-scale, short-term studies may lead to misrepresentations of the needs of grassland-nesting birds.

The evolution of cerebellum structure correlates with nest complexity.

PubMed

Hall, Zachary J; Street, Sally E; Healy, Susan D

2013-01-01

Across the brains of different bird species, the cerebellum varies greatly in the amount of surface folding (foliation). The degree of cerebellar foliation is thought to correlate positively with the processing capacity of the cerebellum, supporting complex motor abilities, particularly manipulative skills. Here, we tested this hypothesis by investigating the relationship between cerebellar foliation and species-typical nest structure in birds. Increasing complexity of nest structure is a measure of a bird's ability to manipulate nesting material into the required shape. Consistent with our hypothesis, avian cerebellar foliation increases as the complexity of the nest built increases, setting the scene for the exploration of nest building at the neural level.

Structural and Practical Identifiability Issues of Immuno-Epidemiological Vector-Host Models with Application to Rift Valley Fever.

PubMed

Tuncer, Necibe; Gulbudak, Hayriye; Cannataro, Vincent L; Martcheva, Maia

2016-09-01

In this article, we discuss the structural and practical identifiability of a nested immuno-epidemiological model of arbovirus diseases, where host-vector transmission rate, host recovery, and disease-induced death rates are governed by the within-host immune system. We incorporate the newest ideas and the most up-to-date features of numerical methods to fit multi-scale models to multi-scale data. For an immunological model, we use Rift Valley Fever Virus (RVFV) time-series data obtained from livestock under laboratory experiments, and for an epidemiological model we incorporate a human compartment to the nested model and use the number of human RVFV cases reported by the CDC during the 2006-2007 Kenya outbreak. We show that the immunological model is not structurally identifiable for the measurements of time-series viremia concentrations in the host. Thus, we study the non-dimensionalized and scaled versions of the immunological model and prove that both are structurally globally identifiable. After fixing estimated parameter values for the immunological model derived from the scaled model, we develop a numerical method to fit observable RVFV epidemiological data to the nested model for the remaining parameter values of the multi-scale system. For the given (CDC) data set, Monte Carlo simulations indicate that only three parameters of the epidemiological model are practically identifiable when the immune model parameters are fixed. Alternatively, we fit the multi-scale data to the multi-scale model simultaneously. Monte Carlo simulations for the simultaneous fitting suggest that the parameters of the immunological model and the parameters of the immuno-epidemiological model are practically identifiable. We suggest that analytic approaches for studying the structural identifiability of nested models are a necessity, so that identifiable parameter combinations can be derived to reparameterize the nested model to obtain an identifiable one. This is a crucial step in developing multi-scale models which explain multi-scale data.

Big Atoms for Small Children: Building Atomic Models from Common Materials to Better Visualize and Conceptualize Atomic Structure

ERIC Educational Resources Information Center

Cipolla, Laura; Ferrari, Lia A.

2016-01-01

A hands-on approach to introduce the chemical elements and the atomic structure to elementary/middle school students is described. The proposed classroom activity presents Bohr models of atoms using common and inexpensive materials, such as nested plastic balls, colored modeling clay, and small-sized pasta (or small plastic beads).

Eggshell Porosity Provides Insight on Evolution of Nesting in Dinosaurs.

PubMed

Tanaka, Kohei; Zelenitsky, Darla K; Therrien, François

2015-01-01

Knowledge about the types of nests built by dinosaurs can provide insight into the evolution of nesting and reproductive behaviors among archosaurs. However, the low preservation potential of their nesting materials and nesting structures means that most information can only be gleaned indirectly through comparison with extant archosaurs. Two general nest types are recognized among living archosaurs: 1) covered nests, in which eggs are incubated while fully covered by nesting material (as in crocodylians and megapodes), and 2) open nests, in which eggs are exposed in the nest and brooded (as in most birds). Previously, dinosaur nest types had been inferred by estimating the water vapor conductance (i.e., diffusive capacity) of their eggs, based on the premise that high conductance corresponds to covered nests and low conductance to open nests. However, a lack of statistical rigor and inconsistencies in this method render its application problematic and its validity questionable. As an alternative we propose a statistically rigorous approach to infer nest type based on large datasets of eggshell porosity and egg mass compiled for over 120 extant archosaur species and 29 archosaur extinct taxa/ootaxa. The presence of a strong correlation between eggshell porosity and nest type among extant archosaurs indicates that eggshell porosity can be used as a proxy for nest type, and thus discriminant analyses can help predict nest type in extinct taxa. Our results suggest that: 1) covered nests are likely the primitive condition for dinosaurs (and probably archosaurs), and 2) open nests first evolved among non-avian theropods more derived than Lourinhanosaurus and were likely widespread in non-avian maniraptorans, well before the appearance of birds. Although taphonomic evidence suggests that basal open nesters (i.e., oviraptorosaurs and troodontids) were potentially the first dinosaurs to brood their clutches, they still partially buried their eggs in sediment. Open nests with fully exposed eggs only became widespread among Euornithes. A potential co-evolution of open nests and brooding behavior among maniraptorans may have freed theropods from the ground-based restrictions inherent to covered nests and allowed the exploitation of alternate nesting locations. These changes in nesting styles and behaviors thus may have played a role in the evolutionary success of maniraptorans (including birds).

Eggshell Porosity Provides Insight on Evolution of Nesting in Dinosaurs

PubMed Central

2015-01-01

Knowledge about the types of nests built by dinosaurs can provide insight into the evolution of nesting and reproductive behaviors among archosaurs. However, the low preservation potential of their nesting materials and nesting structures means that most information can only be gleaned indirectly through comparison with extant archosaurs. Two general nest types are recognized among living archosaurs: 1) covered nests, in which eggs are incubated while fully covered by nesting material (as in crocodylians and megapodes), and 2) open nests, in which eggs are exposed in the nest and brooded (as in most birds). Previously, dinosaur nest types had been inferred by estimating the water vapor conductance (i.e., diffusive capacity) of their eggs, based on the premise that high conductance corresponds to covered nests and low conductance to open nests. However, a lack of statistical rigor and inconsistencies in this method render its application problematic and its validity questionable. As an alternative we propose a statistically rigorous approach to infer nest type based on large datasets of eggshell porosity and egg mass compiled for over 120 extant archosaur species and 29 archosaur extinct taxa/ootaxa. The presence of a strong correlation between eggshell porosity and nest type among extant archosaurs indicates that eggshell porosity can be used as a proxy for nest type, and thus discriminant analyses can help predict nest type in extinct taxa. Our results suggest that: 1) covered nests are likely the primitive condition for dinosaurs (and probably archosaurs), and 2) open nests first evolved among non-avian theropods more derived than Lourinhanosaurus and were likely widespread in non-avian maniraptorans, well before the appearance of birds. Although taphonomic evidence suggests that basal open nesters (i.e., oviraptorosaurs and troodontids) were potentially the first dinosaurs to brood their clutches, they still partially buried their eggs in sediment. Open nests with fully exposed eggs only became widespread among Euornithes. A potential co-evolution of open nests and brooding behavior among maniraptorans may have freed theropods from the ground-based restrictions inherent to covered nests and allowed the exploitation of alternate nesting locations. These changes in nesting styles and behaviors thus may have played a role in the evolutionary success of maniraptorans (including birds). PMID:26605799

Weather radar data correlate to hail-induced mortality in grassland birds

USGS Publications Warehouse

Carver, Amber; Ross, Jeremy D.; Augustine, David J.; Skagen, Susan K.; Dwyer, Angela M.; Tomback, Diana F.; Wunder, Michael B.

2017-01-01

Small-bodied terrestrial animals such as songbirds (Order Passeriformes) are especially vulnerable to hail-induced mortality; yet, hail events are challenging to predict, and they often occur in locations where populations are not being studied. Focusing on nesting grassland songbirds, we demonstrate a novel approach to estimate hail-induced mortality. We quantify the relationship between the probability of nests destroyed by hail and measured Level-III Next Generation Radar (NEXRAD) data, including atmospheric base reflectivity, maximum estimated size of hail and maximum estimated azimuthal wind shear. On 22 June 2014, a hailstorm in northern Colorado destroyed 102 out of 203 known nests within our research site. Lark bunting (Calamospiza melanocorys) nests comprised most of the sample (n = 186). Destroyed nests were more likely to be found in areas of higher storm intensity, and distributions of NEXRAD variables differed between failed and surviving nests. For 133 ground nests where nest-site vegetation was measured, we examined the ameliorative influence of woody vegetation, nest cover and vegetation density by comparing results for 13 different logistic regression models incorporating the independent and additive effects of weather and vegetation variables. The most parsimonious model used only the interactive effect of hail size and wind shear to predict the probability of nest survival, and the data provided no support for any of the models without this predictor. We conclude that vegetation structure may not mitigate mortality from severe hailstorms and that weather radar products can be used remotely to estimate potential for hail mortality of nesting grassland birds. These insights will improve the efficacy of grassland bird population models under predicted climate change scenarios.

A 3-level Bayesian mixed effects location scale model with an application to ecological momentary assessment data.

PubMed

Lin, Xiaolei; Mermelstein, Robin J; Hedeker, Donald

2018-06-15

Ecological momentary assessment studies usually produce intensively measured longitudinal data with large numbers of observations per unit, and research interest is often centered around understanding the changes in variation of people's thoughts, emotions and behaviors. Hedeker et al developed a 2-level mixed effects location scale model that allows observed covariates as well as unobserved variables to influence both the mean and the within-subjects variance, for a 2-level data structure where observations are nested within subjects. In some ecological momentary assessment studies, subjects are measured at multiple waves, and within each wave, subjects are measured over time. Li and Hedeker extended the original 2-level model to a 3-level data structure where observations are nested within days and days are then nested within subjects, by including a random location and scale intercept at the intermediate wave level. However, the 3-level random intercept model assumes constant response change rate for both the mean and variance. To account for changes in variance across waves, as well as clustering attributable to waves, we propose a more comprehensive location scale model that allows subject heterogeneity at baseline as well as across different waves, for a 3-level data structure where observations are nested within waves and waves are then further nested within subjects. The model parameters are estimated using Markov chain Monte Carlo methods. We provide details on the Bayesian estimation approach and demonstrate how the Stan statistical software can be used to sample from the desired distributions and achieve consistent estimates. The proposed model is validated via a series of simulation studies. Data from an adolescent smoking study are analyzed to demonstrate this approach. The analyses clearly favor the proposed model and show significant subject heterogeneity at baseline as well as change over time, for both mood mean and variance. The proposed 3-level location scale model can be widely applied to areas of research where the interest lies in the consistency in addition to the mean level of the responses. Copyright © 2018 John Wiley & Sons, Ltd.

Nest Site Characteristics of Cavity Nesting Birds in Central Missouri

Treesearch

Jeffery D. Brawn; Bernice Tannenbaum; Keith E. Evans

1984-01-01

Two study sites in central Missouri oak-hickory forests were searched for nest sites of cavity nesting birds. Researchers located and measured 133 nests of 11 species. Cavity nesting bird habitat selection is affected by both snag characteristics and vegetation structure.

The Antsy Social Network: Determinants of Nest Structure and Arrangement in Asian Weaver Ants.

PubMed

Devarajan, Kadambari

2016-01-01

Asian weaver ants (Oecophylla smaragdina) are arboreal ants that are known to form mutualistic complexes with their host trees. They are eusocial ants that build elaborate nests in the canopy in tropical areas. A colony comprises of multiple nests, usually on multiple trees, and the boundaries of the colony may be difficult to identify. However, they provide the ideal model for studying group living in invertebrates since there are a definite number of nests for a given substrate, the tree. Here, we briefly examine the structure of the nests and the processes involved in the construction and maintenance of these nests. We have described the spatial arrangement of weaver ant nests on trees in two distinct tropical clusters, a few hundred kilometres apart in India. Measurements were made for 13 trees with a total of 71 nests in the two field sites. We have considered a host of biotic and abiotic factors that may be crucial in determining the location of the nesting site by Asian weaver ants. Our results indicate that tree characteristics and architecture followed by leaf features help determine nest location in Asian weaver ants. While environmental factors may not be as influential to nest arrangement, they seem to be important determinants of nest structure. The parameters that may be considered in establishing the nests could be crucial in picking the evolutionary drivers for colonial living in social organisms.

Nest size is predicted by female identity and the local environment in the blue tit (Cyanistes caeruleus), but is not related to the nest size of the genetic or foster mother

PubMed Central

Parker, Timothy H.; Griffith, Simon C.

2018-01-01

The potential for animals to respond to changing climates has sparked interest in intraspecific variation in avian nest structure since this may influence nest microclimate and protect eggs and offspring from inclement weather. However, there have been relatively few large-scale attempts to examine variation in nests or the determinates of individual variation in nest structure within populations. Using a set of mostly pre-registered analyses, we studied potential predictors of variation in the size of a large sample (803) of blue tit (Cyanistes caeruleus) nests across three breeding seasons at Wytham Woods, UK. While our pre-registered analyses found that individual females built very similar nests across years, there was no evidence in follow-up (post hoc) analyses that their nest size correlated to that of their genetic mother or, in a cross-fostering experiment, to the nest where they were reared. In further pre-registered analyses, spatial environmental variability explained nest size variability at relatively broad spatial scales, and especially strongly at the scale of individual nest boxes. Our study indicates that nest structure is a characteristic of individuals, but is not strongly heritable, indicating that it will not respond rapidly to selection. Explaining the within-individual and within-location repeatability we observed requires further study. PMID:29765658

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

3D deformable image matching: a hierarchical approach over nested subspaces

NASA Astrophysics Data System (ADS)

Musse, Olivier; Heitz, Fabrice; Armspach, Jean-Paul

2000-06-01

This paper presents a fast hierarchical method to perform dense deformable inter-subject matching of 3D MR Images of the brain. To recover the complex morphological variations in neuroanatomy, a hierarchy of 3D deformations fields is estimated, by minimizing a global energy function over a sequence of nested subspaces. The nested subspaces, generated from a single scaling function, consist of deformation fields constrained at different scales. The highly non linear energy function, describing the interactions between the target and the source images, is minimized using a coarse-to-fine continuation strategy over this hierarchy. The resulting deformable matching method shows low sensitivity to local minima and is able to track large non-linear deformations, with moderate computational load. The performances of the approach are assessed both on simulated 3D transformations and on a real data base of 3D brain MR Images from different individuals. The method has shown efficient in putting into correspondence the principle anatomical structures of the brain. An application to atlas-based MRI segmentation, by transporting a labeled segmentation map on patient data, is also presented.

Risk of predation and weather events affect nest site selection by sympatric Pacific (Gavia pacifica) and Yellow-billed (Gavia adamsii) loons in Arctic habitats

USGS Publications Warehouse

Haynes, Trevor B.; Schmutz, Joel A.; Lindberg, Mark S.; Rosenberger, Amanda E.

2014-01-01

Pacific (Gavia pacifica) and Yellow-billed (G. adamsii) loons nest sympatrically in Arctic regions. These related species likely face similar constraints and requirements for nesting success; therefore, use of similar habitats and direct competition for nesting habitat is likely. Both of these loon species must select a breeding lake that provides suitable habitat for nesting and raising chicks; however, characteristics of nest site selection by either species on interior Arctic lakes remains poorly understood. Here, logistic regression was used to compare structural and habitat characteristics of all loon nest locations with random points from lakes on the interior Arctic Coastal Plain, Alaska. Results suggest that both loon species select nest sites to avoid predation and exposure to waves and shifting ice. Loon nest sites were more likely to be on islands and peninsulas (odds ratio = 16.13, 95% CI = 4.64–56.16) than mainland shoreline, which may help loons avoid terrestrial predators. Further, nest sites had a higher degree of visibility (mean degrees of visibility to 100 and 200 m) of approaching predators than random points (odds ratio = 2.57, 95% CI = 1.22–5.39). Nests were sheltered from exposure, having lower odds of being exposed to prevailing winds (odds ratio = 0.34, 95% CI = 0.13–0.92) and lower odds of having high fetch values (odds ratio = 0.46, 95% CI = 0.22–0.96). Differences between Pacific and Yellow-billed loon nesting sites were subtle, suggesting that both species have similar general nest site requirements. However, Yellow-billed Loons nested at slightly higher elevations and were more likely to nest on peninsulas than Pacific Loons. Pacific Loons constructed built up nests from mud and vegetation, potentially in response to limited access to suitable shoreline due to other territorial loons. Results suggest that land managers wishing to protect habitats for these species should focus on lakes with islands as well as shorelines sheltered from exposure to prevailing wind and ice patterns.

Stigmergic construction and topochemical information shape ant nest architecture

PubMed Central

Khuong, Anaïs; Gautrais, Jacques; Perna, Andrea; Sbaï, Chaker; Combe, Maud; Kuntz, Pascale; Jost, Christian; Theraulaz, Guy

2016-01-01

The nests of social insects are not only impressive because of their sheer complexity but also because they are built from individuals whose work is not centrally coordinated. A key question is how groups of insects coordinate their building actions. Here, we use a combination of experimental and modeling approaches to investigate nest construction in the ant Lasius niger. We quantify the construction dynamics and the 3D structures built by ants. Then, we characterize individual behaviors and the interactions of ants with the structures they build. We show that two main interactions are involved in the coordination of building actions: (i) a stigmergic-based interaction that controls the amplification of depositions at some locations and is attributable to a pheromone added by ants to the building material; and (ii) a template-based interaction in which ants use their body size as a cue to control the height at which they start to build a roof from existing pillars. We then develop a 3D stochastic model based on these individual behaviors to analyze the effect of pheromone presence and strength on construction dynamics. We show that the model can quantitatively reproduce key features of construction dynamics, including a large-scale pattern of regularly spaced pillars, the formation and merging of caps over the pillars, and the remodeling of built structures. Finally, our model suggests that the lifetime of the pheromone is a highly influential parameter that controls the growth and form of nest architecture. PMID:26787857

Stigmergic construction and topochemical information shape ant nest architecture.

PubMed

Khuong, Anaïs; Gautrais, Jacques; Perna, Andrea; Sbaï, Chaker; Combe, Maud; Kuntz, Pascale; Jost, Christian; Theraulaz, Guy

2016-02-02

The nests of social insects are not only impressive because of their sheer complexity but also because they are built from individuals whose work is not centrally coordinated. A key question is how groups of insects coordinate their building actions. Here, we use a combination of experimental and modeling approaches to investigate nest construction in the ant Lasius niger. We quantify the construction dynamics and the 3D structures built by ants. Then, we characterize individual behaviors and the interactions of ants with the structures they build. We show that two main interactions are involved in the coordination of building actions: (i) a stigmergic-based interaction that controls the amplification of depositions at some locations and is attributable to a pheromone added by ants to the building material; and (ii) a template-based interaction in which ants use their body size as a cue to control the height at which they start to build a roof from existing pillars. We then develop a 3D stochastic model based on these individual behaviors to analyze the effect of pheromone presence and strength on construction dynamics. We show that the model can quantitatively reproduce key features of construction dynamics, including a large-scale pattern of regularly spaced pillars, the formation and merging of caps over the pillars, and the remodeling of built structures. Finally, our model suggests that the lifetime of the pheromone is a highly influential parameter that controls the growth and form of nest architecture.

Lifespan Analyses of Forest Raptor Nests: Patterns of Creation, Persistence and Reuse

PubMed Central

Jiménez-Franco, María V.; Martínez, José E.; Calvo, José F.

2014-01-01

Structural elements for breeding such as nests are key resources for the conservation of bird populations. This is especially true when structural elements require a specific and restricted habitat, or if the construction of nests is costly in time and energy. The availability of nesting-platforms is influenced by nest creation and persistence. In a Mediterranean forest in southeastern Spain, nesting-platforms are the only structural element for three forest-dwelling raptor species: booted eagle Aquila pennata, common buzzard Buteo buteo and northern goshawk Accipiter gentilis. From 1998 to 2013, we tracked the fate of 157 nesting-platforms built and reused by these species with the aim of determining the rates of creation and destruction of nesting-platforms, estimating nest persistence by applying two survival analyses, describing the pattern of nest reuse and testing the effects of nest use on breeding success. Nest creation and destruction rates were low (0.14 and 0.05, respectively). Using Kaplan Meier survival estimates and Cox proportional-hazards regression models we found that median nest longevity was 12 years and that this was not significantly affected by nest characteristics, nest-tree dimensions, nest-builder species, or frequency of use of the platform. We also estimated a transition matrix, considering the different stages of nest occupation (vacant or occupied by one of the focal species), to obtain the fundamental matrix and the average life expectancies of nests, which varied from 17.9 to 19.7 years. Eighty six percent of nests were used in at least one breeding attempt, 67.5% were reused and 17.8% were successively occupied by at least two of the study species. The frequency of nest use had no significant effects on the breeding success of any species. We conclude that nesting-platforms constitute an important resource for forest raptors and that their longevity is sufficiently high to allow their reuse in multiple breeding attempts. PMID:24717935

Lifespan analyses of forest raptor nests: patterns of creation, persistence and reuse.

PubMed

Jiménez-Franco, María V; Martínez, José E; Calvo, José F

2014-01-01

Structural elements for breeding such as nests are key resources for the conservation of bird populations. This is especially true when structural elements require a specific and restricted habitat, or if the construction of nests is costly in time and energy. The availability of nesting-platforms is influenced by nest creation and persistence. In a Mediterranean forest in southeastern Spain, nesting-platforms are the only structural element for three forest-dwelling raptor species: booted eagle Aquila pennata, common buzzard Buteo buteo and northern goshawk Accipiter gentilis. From 1998 to 2013, we tracked the fate of 157 nesting-platforms built and reused by these species with the aim of determining the rates of creation and destruction of nesting-platforms, estimating nest persistence by applying two survival analyses, describing the pattern of nest reuse and testing the effects of nest use on breeding success. Nest creation and destruction rates were low (0.14 and 0.05, respectively). Using Kaplan Meier survival estimates and Cox proportional-hazards regression models we found that median nest longevity was 12 years and that this was not significantly affected by nest characteristics, nest-tree dimensions, nest-builder species, or frequency of use of the platform. We also estimated a transition matrix, considering the different stages of nest occupation (vacant or occupied by one of the focal species), to obtain the fundamental matrix and the average life expectancies of nests, which varied from 17.9 to 19.7 years. Eighty six percent of nests were used in at least one breeding attempt, 67.5% were reused and 17.8% were successively occupied by at least two of the study species. The frequency of nest use had no significant effects on the breeding success of any species. We conclude that nesting-platforms constitute an important resource for forest raptors and that their longevity is sufficiently high to allow their reuse in multiple breeding attempts.

The Advantages of Hierarchical Linear Modeling. ERIC/AE Digest.

ERIC Educational Resources Information Center

Osborne, Jason W.

This digest introduces hierarchical data structure, describes how hierarchical models work, and presents three approaches to analyzing hierarchical data. Hierarchical, or nested data, present several problems for analysis. People or creatures that exist within hierarchies tend to be more similar to each other than people randomly sampled from the…

When social behaviour is moulded in clay: on growth and form of social insect nests.

PubMed

Perna, Andrea; Theraulaz, Guy

2017-01-01

The nests built by social insects are among the most complex structures produced by animal groups. They reveal the social behaviour of a colony and as such they potentially allow comparative studies. However, for a long time, research on nest architecture was hindered by the lack of technical tools allowing the visualisation of their complex 3D structures and the quantification of their properties. Several techniques, developed over the years, now make it possible to study the organisation of these nests and how they are built. Here, we review present knowledge of the mechanisms of nest construction, and how nest structure affects the behaviour of individual insects and the organisation of activities within a colony. © 2017. Published by The Company of Biologists Ltd.

Nest site characteristics of three coexisting Accipiter hawks in northeastern Oregon

USGS Publications Warehouse

Moore, K.R.; Henny, C.J.

1983-01-01

Habitat data were evaluated at 34 Goshawk (Accipiter gentilis), 31 Cooper's Hawk (A. cooperii), and 15 Sharp-shinned Hawk (A. striatus) nest sites in coniferous forests of northeastern Oregon. Crown volume profiles indicate a strong similarity in vegetative structure at nest sites of cooperii and striatus; both commonly nest in younger successional stands than gentilis. Habitat separation of nest sites among the three species was illustrated using a stepwise discriminant analysis; 88% of all gentilis sites were correctly classified. Interspecific overlap in nest site habitat was further demonstrated using a canonical analysis of habitat variables. Nest site habitat space of gentilis is distinct and is less variable in structure than that of the other species. Cooperii preferred nesting sites with norhern aspects, whereas striatus and gentilis showed no preference. The use of mistletoe (Arceuthobium sp.) growth by cooperii for nest platforms (64% of all nests) may explain its preference for Douglas fir (Pseudotsuga menziesii) as a nesting tree. Douglas fir is most commonly parasitized by mistletoe.

Damage tolerant design using collapse techniques

NASA Technical Reports Server (NTRS)

Haftka, R. T.

1982-01-01

A new approach to the design of structures for improved global damage tolerance is presented. In its undamaged condition the structure is designed subject to strength, displacement and buckling constraints. In the damaged condition the only constraint is that the structure will not collapse. The collapse load calculation is formulated as a maximization problem and solved by an interior extended penalty function. The design for minimum weight subject to constraints on the undamaged structure and a specified level of the collapse load is a minimization problem which is also solved by a penalty function formulation. Thus the overall problem is of a nested or multilevel optimization. Examples are presented to demonstrate the difference between the present and more traditional approaches.

Time-varying effect moderation using the structural nested mean model: estimation using inverse-weighted regression with residuals

PubMed Central

Almirall, Daniel; Griffin, Beth Ann; McCaffrey, Daniel F.; Ramchand, Rajeev; Yuen, Robert A.; Murphy, Susan A.

2014-01-01

This article considers the problem of examining time-varying causal effect moderation using observational, longitudinal data in which treatment, candidate moderators, and possible confounders are time varying. The structural nested mean model (SNMM) is used to specify the moderated time-varying causal effects of interest in a conditional mean model for a continuous response given time-varying treatments and moderators. We present an easy-to-use estimator of the SNMM that combines an existing regression-with-residuals (RR) approach with an inverse-probability-of-treatment weighting (IPTW) strategy. The RR approach has been shown to identify the moderated time-varying causal effects if the time-varying moderators are also the sole time-varying confounders. The proposed IPTW+RR approach provides estimators of the moderated time-varying causal effects in the SNMM in the presence of an additional, auxiliary set of known and measured time-varying confounders. We use a small simulation experiment to compare IPTW+RR versus the traditional regression approach and to compare small and large sample properties of asymptotic versus bootstrap estimators of the standard errors for the IPTW+RR approach. This article clarifies the distinction between time-varying moderators and time-varying confounders. We illustrate the methodology in a case study to assess if time-varying substance use moderates treatment effects on future substance use. PMID:23873437

Enclosed nests may provide greater thermal than nest predation benefits compared with open nests across latitudes

USGS Publications Warehouse

Martin, Thomas E.; Boyce, Andy J.; Fierro-Calderon, Karolina; Mitchell, Adam E.; Armstad, Connor E.; Mouton, James C.; Bin Soudi, Evertius E.

2017-01-01

Nest structure is thought to provide benefits that have fitness consequences for several taxa. Traditionally, reduced nest predation has been considered the primary benefit underlying evolution of nest structure, whereas thermal benefits have been considered a secondary or even non-existent factor. Yet, the relative roles of these factors on nest structures remain largely unexplored.Enclosed nests have a constructed or natural roof connected to sides that allow a restricted opening or tube entrance that provides cover in all directions except the entrance, whereas open nests are cups or platforms that are open above. We show that construction of enclosed nests is more common among songbirds (Passeriformes) in tropical and southern hemisphere regions than in north temperate regions. This geographic pattern may reflect selection from predation risk, under long-standing assumptions that nest predation rates are higher in southern regions and that enclosed nests reduce predation risk compared with open cup nests. We therefore compared nest predation rates between enclosed vs. open nests in 114 songbird species that do not nest in tree holes among five communities of coexisting birds, and for 205 non-hole-nesting species from the literature, across northern temperate, tropical, and southern hemisphere regions.Among coexisting species, enclosed nests had lower nest predation rates than open nests in two south temperate sites, but not in either of two tropical sites or a north temperate site. Nest predation did not differ between nest types at any latitude based on literature data. Among 319 species from both our field studies and the literature, enclosed nests did not show consistent benefits of reduced predation and, in fact, predation was not consistently higher in the tropics, contrary to long-standing perspectives.Thermal benefits of enclosed nests were indicated based on three indirect results. First, species that built enclosed nests were smaller than species using open nests both among coexisting species and among species from the literature. Smaller species lose heat fastest and thereby may gain important thermal benefits from reduced convective cooling. Second, eggs were warmed by parents for less time in species with enclosed nests, as can be expected if egg cooling rates are slower. Finally, species using enclosed nests exhibited enhanced growth of mass and wings compared with species using open nests, suggesting reduced thermoregulatory costs allowed increased energy for growth.Enclosed nests may therefore provide more consistent thermal than nest predation benefits, counter to long-standing perspectives.

New homes for prairie ducks

USGS Publications Warehouse

Doty, H.A.

1970-01-01

This pamphlet describes how to make, install and care for inexpensive duck nesting baskets. Ducks have been attracted to these structures in the prairies of eastern North and South Dakota, western Minnesota, and northern Iowa. Nesting structures can help increase the number of local nesting ducks, especially mallards.

Effects of shallow natural gas well structures and associated roads on grassland songbird reproductive success in Alberta, Canada

PubMed Central

Koper, Nicola

2017-01-01

Grassland songbird populations across North America have experienced dramatic population declines due to habitat loss and degradation. In Canada, energy development continues to fragment and disturb prairie habitat, but effects of oil and gas development on reproductive success of songbirds in North American mixed-grass prairies remains largely unknown. From 2010–2012, in southeastern Alberta, Canada, we monitored 257 nests of two ground-nesting grassland songbird species, Savannah sparrow (Passerculus sandwichensis) and chestnut-collared longspur (Calcarius ornatus). Nest locations varied with proximity to and density of conventional shallow gas well structures and associated roads in forty-two 258-ha mixed-grass prairie sites. We estimated the probabilities of nest success and clutch size relative to gas well structures and roads. There was little effect of distance to or density of gas well structure on nest success; however, Savannah sparrow experienced lower nest success near roads. Clutch sizes were lower near gas well structures and cattle water sources. Minimizing habitat disturbance surrounding gas well structures, and reducing abundance of roads and trails, would help minimize impacts on reproductive success for some grassland songbirds. PMID:28355241

Effects of shallow natural gas well structures and associated roads on grassland songbird reproductive success in Alberta, Canada.

PubMed

Yoo, Jenny; Koper, Nicola

2017-01-01

Grassland songbird populations across North America have experienced dramatic population declines due to habitat loss and degradation. In Canada, energy development continues to fragment and disturb prairie habitat, but effects of oil and gas development on reproductive success of songbirds in North American mixed-grass prairies remains largely unknown. From 2010-2012, in southeastern Alberta, Canada, we monitored 257 nests of two ground-nesting grassland songbird species, Savannah sparrow (Passerculus sandwichensis) and chestnut-collared longspur (Calcarius ornatus). Nest locations varied with proximity to and density of conventional shallow gas well structures and associated roads in forty-two 258-ha mixed-grass prairie sites. We estimated the probabilities of nest success and clutch size relative to gas well structures and roads. There was little effect of distance to or density of gas well structure on nest success; however, Savannah sparrow experienced lower nest success near roads. Clutch sizes were lower near gas well structures and cattle water sources. Minimizing habitat disturbance surrounding gas well structures, and reducing abundance of roads and trails, would help minimize impacts on reproductive success for some grassland songbirds.

Why are some plant-pollinator networks more nested than others?

PubMed

Song, Chuliang; Rohr, Rudolf P; Saavedra, Serguei

2017-10-01

Empirical studies have found that the mutualistic interactions forming the structure of plant-pollinator networks are typically more nested than expected by chance alone. Additionally, theoretical studies have shown a positive association between the nested structure of mutualistic networks and community persistence. Yet, it has been shown that some plant-pollinator networks may be more nested than others, raising the interesting question of which factors are responsible for such enhanced nested structure. It has been argued that ordered network structures may increase the persistence of ecological communities under less predictable environments. This suggests that nested structures of plant-pollinator networks could be more advantageous under highly seasonal environments. While several studies have investigated the link between nestedness and various environmental variables, unfortunately, there has been no unified answer to validate these predictions. Here, we move from the problem of describing network structures to the problem of comparing network structures. We develop comparative statistics, and apply them to investigate the association between the nested structure of 59 plant-pollinator networks and the temperature seasonality present in their locations. We demonstrate that higher levels of nestedness are associated with a higher temperature seasonality. We show that the previous lack of agreement came from an extended practice of using standardized measures of nestedness that cannot be compared across different networks. Importantly, our observations complement theory showing that more nested network structures can increase the range of environmental conditions compatible with species coexistence in mutualistic systems, also known as structural stability. This increase in nestedness should be more advantageous and occur more often in locations subject to random environmental perturbations, which could be driven by highly changing or seasonal environments. This synthesis of theory and observations could prove relevant for a better understanding of the ecological processes driving the assembly and persistence of ecological communities. © 2017 The Authors. Journal of Animal Ecology © 2017 British Ecological Society.

Two-way against one-way nesting for climate downscaling in Europe and the Mediterranean region using LMDZ4

NASA Astrophysics Data System (ADS)

Li, Shan; Li, Laurent; Le Treut, Hervé

2016-04-01

In the 21st century, the estimated surface temperature warming projected by General Circulation Models (GCMs) is between 0.3 and 4.8 °C, depending on the scenario considered. GCMs exhibit a good representation of climate on a global scale, but they are not able to reproduce regional climate processes with the same level of accuracy. Society and policymakers need model projections to define climate change adaptation and mitigation policies on a global, regional and local scale. Climate downscaling is mostly conducted with a regional model nested into the outputs of a global model. This one-way nesting approach is generally used in the climate community without feedbacks from Regional Climate Models (RCMs) to GCMs. This lack of interaction between the two models may affect regional modes of variability, in particular those with a boundary conflict. The objective of this study is to evaluate a two-way nesting configuration that makes an interactive coupling between the RCM and the GCM, an approach against the traditional configuration of one-way nesting system. An additional aim of this work is to examine if the two-way nesting system can improve the RCM performance. The atmospheric component of the IPSL integrated climate model (LMDZ) is configured at both regional (LMDZ-regional) and global (LMDZ-global) scales. The two models have the same configuration for the dynamical framework and the physical forcings. The climatology values of sea surface temperature (SST) are prescribed for the two models. The stretched-grid of LMDZ-global is applied to a region defined by Europe, the Mediterranean, North Africa and Western North Atlantic. To ensure a good statistical significance of results, all simulations last at least 80 years. The nesting process of models is performed by a relaxation procedure of a time scale of 90 minutes. In the case of two-way nesting, the exchange between the two models is every two hours. The relaxation procedure induces a boundary conflict, particularly in the eastern boundary for temperature and geopotential height. A correlation analysis on the synoptic scale evaluates the relationship between the GCM and the RCM. The beginning of the simulations shows a great consistency of the two models. When dominant dynamics apply, RCM inherits most of the GCM signal with a consistent spatial structure. On the contrary, when the atmospheric circulation is weak, there are not that many effects transferred from the GCM to the RCM. When the RCM has its own dynamics, the boundary conflict is more pronounced. Winter season is chosen for the two-way nesting test due to the predominant role of the atmospheric dynamics in winter. The new approach of a two-way nesting system reduces boundary bias, having a influence in some cases in climate model projections. The effect of two-way nesting is enhanced when using a finer grid.

Comparing Treatment Policies with Assistance from the Structural Nested Mean Model

PubMed Central

Lu, Xi; Lynch, Kevin G.; Oslin, David W.; Murphy, Susan

2015-01-01

Summary Treatment policies, also known as dynamic treatment regimes, are sequences of decision rules that link the observed patient history with treatment recommendations. Multiple, plausible, treatment policies are frequently constructed by researchers using expert opinion, theories and reviews of the literature. Often these different policies represent competing approaches to managing an illness. Here we develop an “assisted estimator” that can be used to compare the mean outcome of competing treatment policies. The term “assisted” refers to the fact estimators from the Structural Nested Mean Model, a parametric model for the causal effect of treatment at each time point, are used in the process of estimating the mean outcome. This work is motivated by our work on comparing the mean outcome of two competing treatment policies using data from the ExTENd study in alcohol dependence. PMID:26363892

Nested effects models for learning signaling networks from perturbation data.

PubMed

Fröhlich, Holger; Tresch, Achim; Beissbarth, Tim

2009-04-01

Targeted gene perturbations have become a major tool to gain insight into complex cellular processes. In combination with the measurement of downstream effects via DNA microarrays, this approach can be used to gain insight into signaling pathways. Nested Effects Models were first introduced by Markowetz et al. as a probabilistic method to reverse engineer signaling cascades based on the nested structure of downstream perturbation effects. The basic framework was substantially extended later on by Fröhlich et al., Markowetz et al., and Tresch and Markowetz. In this paper, we present a review of the complete methodology with a detailed comparison of so far proposed algorithms on a qualitative and quantitative level. As an application, we present results on estimating the signaling network between 13 genes in the ER-alpha pathway of human MCF-7 breast cancer cells. Comparison with the literature shows a substantial overlap.

Nest survival modelling using a multi-species approach in forests managed for timber and biofuel feedstock

USGS Publications Warehouse

Loman, Zachary G.; Monroe, Adrian; Riffell, Samuel K.; Miller, Darren A.; Vilella, Francisco; Wheat, Bradley R.; Rush, Scott A.; Martin, James A.

2018-01-01

Switchgrass (Panicum virgatum) intercropping is a novel forest management practice for biomass production intended to generate cellulosic feedstocks within intensively managed loblolly pine‐dominated landscapes. These pine plantations are important for early‐successional bird species, as short rotation times continually maintain early‐successional habitat. We tested the efficacy of using community models compared to individual surrogate species models in understanding influences on nest survival. We analysed nest data to test for differences in habitat use for 14 bird species in plots managed for switchgrass intercropping and controls within loblolly pine (Pinus taeda) plantations in Mississippi, USA.We adapted hierarchical models using hyper‐parameters to incorporate information from both common and rare species to understand community‐level nest survival. This approach incorporates rare species that are often discarded due to low sample sizes, but can inform community‐level demographic parameter estimates. We illustrate use of this approach in generating both species‐level and community‐wide estimates of daily survival rates for songbird nests. We were able to include rare species with low sample size (minimum n = 5) to inform a hyper‐prior, allowing us to estimate effects of covariates on daily survival at the community level, then compare this with a single‐species approach using surrogate species. Using single‐species models, we were unable to generate estimates below a sample size of 21 nests per species.Community model species‐level survival and parameter estimates were similar to those generated by five single‐species models, with improved precision in community model parameters.Covariates of nest placement indicated that switchgrass at the nest site (<4 m) reduced daily nest survival, although intercropping at the forest stand level increased daily nest survival.Synthesis and applications. Community models represent a viable method for estimating community nest survival rates and effects of covariates while incorporating limited data for rarely detected species. Intercropping switchgrass in loblolly pine plantations slightly increased daily nest survival at the research plot scale (0.1 km2), although at a local scale (50 m2) switchgrass negatively influenced nest survival. A likely explanation is intercropping shifted community composition, favouring species with greater disturbance tolerance.

The "Russian Doll" Approach: Developing Nested Case-Studies to Support International Comparative Research in Education

ERIC Educational Resources Information Center

Chong, Pei Wen; Graham, Linda J.

2013-01-01

International comparison is complicated by the use of different terms, classification methods, policy frameworks and system structures, not to mention different languages and terminology. Multi-case studies can assist in the understanding of the influence wielded by cultural, social, economic, historical and political forces upon educational…

The structure of gallery networks in the nests of termite Cubitermes spp. revealed by X-ray tomography

NASA Astrophysics Data System (ADS)

Perna, Andrea; Jost, Christian; Couturier, Etienne; Valverde, Sergi; Douady, Stéphane; Theraulaz, Guy

2008-09-01

Recent studies have introduced computer tomography (CT) as a tool for the visualisation and characterisation of insect architectures. Here, we use CT to map the three-dimensional networks of galleries inside Cubitermes nests in order to analyse them with tools from graph theory. The structure of these networks indicates that connections inside the nest are rearranged during the whole nest life. The functional analysis reveals that the final network topology represents an excellent compromise between efficient connectivity inside the nest and defence against attacking predators. We further discuss and illustrate the usefulness of CT to disentangle environmental and specific influences on nest architecture.

Physical cognition: birds learn the structural efficacy of nest material

PubMed Central

Bailey, Ida E.; Morgan, Kate V.; Bertin, Marion; Meddle, Simone L.; Healy, Susan D.

2014-01-01

It is generally assumed that birds’ choice of structurally suitable materials for nest building is genetically predetermined. Here, we tested that assumption by investigating whether experience affected male zebra finches’ (Taeniopygia guttata) choice of nest material. After a short period of building with relatively flexible string, birds preferred to build with stiffer string while those that had experienced a stiffer string were indifferent to string type. After building a complete nest with either string type, however, all birds increased their preference for stiff string. The stiffer string appeared to be the more effective building material as birds required fewer pieces of stiffer than flexible string to build a roofed nest. For birds that raised chicks successfully, there was no association between the material they used to build their nest and the type they subsequently preferred. Birds’ material preference reflected neither the preference of their father nor of their siblings but juvenile experience of either string type increased their preference for stiffer string. Our results represent two important advances: (i) birds choose nest material based on the structural properties of the material; (ii) nest material preference is not entirely genetically predetermined as both the type and amount of experience influences birds’ choices. PMID:24741011

Physical cognition: birds learn the structural efficacy of nest material.

PubMed

Bailey, Ida E; Morgan, Kate V; Bertin, Marion; Meddle, Simone L; Healy, Susan D

2014-06-07

It is generally assumed that birds' choice of structurally suitable materials for nest building is genetically predetermined. Here, we tested that assumption by investigating whether experience affected male zebra finches' (Taeniopygia guttata) choice of nest material. After a short period of building with relatively flexible string, birds preferred to build with stiffer string while those that had experienced a stiffer string were indifferent to string type. After building a complete nest with either string type, however, all birds increased their preference for stiff string. The stiffer string appeared to be the more effective building material as birds required fewer pieces of stiffer than flexible string to build a roofed nest. For birds that raised chicks successfully, there was no association between the material they used to build their nest and the type they subsequently preferred. Birds' material preference reflected neither the preference of their father nor of their siblings but juvenile experience of either string type increased their preference for stiffer string. Our results represent two important advances: (i) birds choose nest material based on the structural properties of the material; (ii) nest material preference is not entirely genetically predetermined as both the type and amount of experience influences birds' choices.

The design and function of birds' nests

PubMed Central

Mainwaring, Mark C; Hartley, Ian R; Lambrechts, Marcel M; Deeming, D Charles

2014-01-01

All birds construct nests in which to lay eggs and/or raise offspring. Traditionally, it was thought that natural selection and the requirement to minimize the risk of predation determined the design of completed nests. However, it is becoming increasingly apparent that sexual selection also influences nest design. This is an important development as while species such as bowerbirds build structures that are extended phenotypic signals whose sole purpose is to attract a mate, nests contain eggs and/or offspring, thereby suggesting a direct trade-off between the conflicting requirements of natural and sexual selection. Nest design also varies adaptively in order to both minimize the detrimental effects of parasites and to create a suitable microclimate for parents and developing offspring in relation to predictable variation in environmental conditions. Our understanding of the design and function of birds' nests has increased considerably in recent years, and the evidence suggests that nests have four nonmutually exclusive functions. Consequently, we conclude that the design of birds' nests is far more sophisticated than previously realized and that nests are multifunctional structures that have important fitness consequences for the builder/s. PMID:25505520

Crucial nesting habitat for gunnison sage-grouse: A spatially explicit hierarchical approach

USGS Publications Warehouse

Aldridge, Cameron L.; Saher, D.J.; Childers, T.M.; Stahlnecker, K.E.; Bowen, Z.H.

2012-01-01

Gunnison sage-grouse (Centrocercus minimus) is a species of special concern and is currently considered a candidate species under Endangered Species Act. Careful management is therefore required to ensure that suitable habitat is maintained, particularly because much of the species' current distribution is faced with exurban development pressures. We assessed hierarchical nest site selection patterns of Gunnison sage-grouse inhabiting the western portion of the Gunnison Basin, Colorado, USA, at multiple spatial scales, using logistic regression-based resource selection functions. Models were selected using Akaike Information Criterion corrected for small sample sizes (AIC c) and predictive surfaces were generated using model averaged relative probabilities. Landscape-scale factors that had the most influence on nest site selection included the proportion of sagebrush cover >5%, mean productivity, and density of 2 wheel-drive roads. The landscape-scale predictive surface captured 97% of known Gunnison sage-grouse nests within the top 5 of 10 prediction bins, implicating 57% of the basin as crucial nesting habitat. Crucial habitat identified by the landscape model was used to define the extent for patch-scale modeling efforts. Patch-scale variables that had the greatest influence on nest site selection were the proportion of big sagebrush cover >10%, distance to residential development, distance to high volume paved roads, and mean productivity. This model accurately predicted independent nest locations. The unique hierarchical structure of our models more accurately captures the nested nature of habitat selection, and allowed for increased discrimination within larger landscapes of suitable habitat. We extrapolated the landscape-scale model to the entire Gunnison Basin because of conservation concerns for this species. We believe this predictive surface is a valuable tool which can be incorporated into land use and conservation planning as well the assessment of future land-use scenarios. ?? 2011 The Wildlife Society.

Discovering Event Structure in Continuous Narrative Perception and Memory.

PubMed

Baldassano, Christopher; Chen, Janice; Zadbood, Asieh; Pillow, Jonathan W; Hasson, Uri; Norman, Kenneth A

2017-08-02

During realistic, continuous perception, humans automatically segment experiences into discrete events. Using a novel model of cortical event dynamics, we investigate how cortical structures generate event representations during narrative perception and how these events are stored to and retrieved from memory. Our data-driven approach allows us to detect event boundaries as shifts between stable patterns of brain activity without relying on stimulus annotations and reveals a nested hierarchy from short events in sensory regions to long events in high-order areas (including angular gyrus and posterior medial cortex), which represent abstract, multimodal situation models. High-order event boundaries are coupled to increases in hippocampal activity, which predict pattern reinstatement during later free recall. These areas also show evidence of anticipatory reinstatement as subjects listen to a familiar narrative. Based on these results, we propose that brain activity is naturally structured into nested events, which form the basis of long-term memory representations. Copyright © 2017 Elsevier Inc. All rights reserved.

Does survey method bias the description of northern goshawk nest-site structure?

USGS Publications Warehouse

Daw, S.K.; DeStefano, S.; Steidl, R.J.

1998-01-01

Past studies on the nesting habitat of northern goshawks (Accipiter gentilis) often relied on nests found opportunistically, either during timber-sale operations, by searching apparently 'good' goshawk habitat, or by other search methods where areas were preselected based on known forest conditions. Therefore, a bias in the characterization of habitat surrounding northern goshawk nest sites may exist toward late-forest structure (large trees, high canopy closure). This potential problem has confounded interpretation of data on nesting habitat of northern goshawks and added to uncertainty in the review process to consider the species for federal listing as threatened or endangered. Systematic survey methods, which strive for complete coverage of an area and often use broadcasts of conspecific calls, have been developed to overcome these potential biases, but no study has compared habitat characteristics around nests found opportunistically with those found systematically. We compared habitat characteristics in a 0.4-ha area around nests found systematically (n = 27) versus those found opportunistically (n = 22) on 3 national forests in eastern Oregon. We found that both density of large trees (systematic: x?? = 16.4 ?? 3.1 trees/ha; x?? ?? SE; opportunistic: x?? = 21.3 ?? 3.2; P = 0.56) and canopy closure (systematic: x?? = 72 ?? 2%; opportunistic: x?? = 70 ?? 2%; P = 0.61) were similar around nests found with either search method. Our results diminish concern that past survey methods mischaracterized northern goshawk nest-site structure. However, because northern goshawks nest in a variety of forest cover types with a wide range of structural characteristics, these results do not decrease the value of systematic survey methods in determining the most representative habitat descriptions for northern goshawks. Rigorous survey protocols allow repeatability and comparability of monitoring efforts and results over time.

Testing models of female reproductive migratory behaviour and population structure in the Caribbean hawksbill turtle, Eretmochelys imbricata, with mtDNA sequences.

PubMed

Bass, A L; Good, D A; Bjorndal, K A; Richardson, J I; Hillis, Z M; Horrocks, J A; Bowen, B W

1996-06-01

Information on the reproductive behaviour and population structure of female hawksbill turtles, Eretmochelys imbricata, is necessary to define conservation priorities for this highly endangered species. Two hypotheses to explain female nest site choice, natal homing and social facilitation, were tested by analyzing mtDNA control region sequences of 103 individuals from seven nesting colonies in the Caribbean and western Atlantic. Under the social facilitation model, newly mature females follow older females to a nesting location, and subsequently use this site for future nesting. This model generates an expectation that female lineages will be homogenized among regional nesting colonies. Contrary to expectations of the social facilitation model, mtDNA lineages were highly structured among western Atlantic nesting colonies. These analyses identified at least 6 female breeding stocks in the Caribbean and western Atlantic and support a natal homing model for recruitment of breeding females. Reproductive populations are effectively isolated over ecological time scales, and recovery plans for this species should include protection at the level of individual nesting colonies.

Nest-site characteristics and linear abundance of cliff-nesting American kestrels on San Clemente Island, California

USGS Publications Warehouse

Sullivan, Brian L.; Kershner, Eric L.; Finn, S.P.; Condon, Anne M.; Cooper, Douglass M.; Garcelon, David K.

2003-01-01

American Kestrels( Falco sparverius) are typically secondary-cavity nesters, and use of natural cliff cavities for nest sites is less-commonly reported. On San Clemente Island (SCI), California, however, American Kestrels nest primarily on cliffs in major canyons(93%), to a lesser extent on seacliffs(4%), as well as in man-made structures (3%). We located and mapped 99 American Kestrel territories on SCI, and recorded 11 nest-site characteristics at 40 cliff nests during 2001-02. Nest cliffs were typically fractured igneous rock with mean height of 16.1 m +_ 1.8 SE. Mean slope of nest cliffs was vertical (x=91 degrees). Nest cliffs and cavities were significantly oriented to the southeast, away from the prevailing wind direction(NW). In eight canyons, where we believe that we found all occupied American Kestrel territories, the mean linear abundance was 2.1 pairs/km, greater than most published estimates. Contrary to most previous studies, no American Kestrels nested in tree cavities despite their presence in SCI canyons. The absence of cavity-excavating breeding birds from the island likely restricts kestrels to nesting in naturally-formed cavities and man-made structures.

Flight initiation by Ferruginous Hawks depends on disturbance type, experience, and the anthropogenic landscape

PubMed Central

Wellicome, Troy I.; Bayne, Erin M.

2017-01-01

The expansion of humans and their related infrastructure is increasing the likelihood that wildlife will interact with humans. When disturbed by humans, animals often change their behaviour, which can result in time and energetic costs to that animal. An animal's decision to change behaviour is likely related to the type of disturbance, the individual's past experience with disturbance, and the landscape in which the disturbance occurs. In southern Alberta and Saskatchewan, we quantified probability of flight initiation from the nest by Ferruginous Hawks (Buteo regalis) during approaches to nests by investigators. We tested if probability of flight was related to different disturbance types, previous experience, and the anthropogenic landscape in which individual Ferruginous Hawks nested. Probability of flight was related to the type of approach by the investigator, the number of previous visits by investigators, and the vehicular traffic around the nest. Approaches by humans on foot resulted in a greater probability of flight than those in a vehicle. Approaches in a vehicle via low traffic volume access roads were related to increased probability of flight relative to other road types. The number of previous investigator approaches to the nest increased the probability of flight. Overall, we found support that Ferruginous Hawks show habituation to vehicles and the positive reinforcement hypotheses as probability of flight was negatively related to an index of traffic activity near the nest. Our work emphasizes that complex, dynamic processes drive the decision to initiate flight from the nest, and contributes to the growing body of work explaining how responses to humans vary within species. PMID:28542334

Flight initiation by Ferruginous Hawks depends on disturbance type, experience, and the anthropogenic landscape.

PubMed

Nordell, Cameron J; Wellicome, Troy I; Bayne, Erin M

2017-01-01

The expansion of humans and their related infrastructure is increasing the likelihood that wildlife will interact with humans. When disturbed by humans, animals often change their behaviour, which can result in time and energetic costs to that animal. An animal's decision to change behaviour is likely related to the type of disturbance, the individual's past experience with disturbance, and the landscape in which the disturbance occurs. In southern Alberta and Saskatchewan, we quantified probability of flight initiation from the nest by Ferruginous Hawks (Buteo regalis) during approaches to nests by investigators. We tested if probability of flight was related to different disturbance types, previous experience, and the anthropogenic landscape in which individual Ferruginous Hawks nested. Probability of flight was related to the type of approach by the investigator, the number of previous visits by investigators, and the vehicular traffic around the nest. Approaches by humans on foot resulted in a greater probability of flight than those in a vehicle. Approaches in a vehicle via low traffic volume access roads were related to increased probability of flight relative to other road types. The number of previous investigator approaches to the nest increased the probability of flight. Overall, we found support that Ferruginous Hawks show habituation to vehicles and the positive reinforcement hypotheses as probability of flight was negatively related to an index of traffic activity near the nest. Our work emphasizes that complex, dynamic processes drive the decision to initiate flight from the nest, and contributes to the growing body of work explaining how responses to humans vary within species.

Department of Defense Natural Resources Program: Songbird Nest Boxes. Section 5.1.8., US Army Corps of Engineers Wildlife Resources Management Manual

DTIC Science & Technology

1988-11-01

SUBJECT TERMS (Continue on reverse if necessary and idenify by block number) FIELD GROUP SUB-GROUP Artificial nesting structures Songbord management...5.1.8 in Chapter 5 -- MANAGEMENT PRACTICES AND TECHNIQUES , Part 5.1 -- NESTING AND ROOSTING STRUCTURES, of the US ARMY CORPS OF ENGINEERS WILDLIFE...natural cavities has become a widely used management technique . Nest box programs have played an important role in the restoration of species such as

Inferences about nested subsets structure when not all species are detected

USGS Publications Warehouse

Cam, E.; Nichols, J.D.; Hines, J.E.; Sauer, J.R.

2000-01-01

Comparisons of species composition among ecological communities of different size have often provided evidence that the species in communities with lower species richness form nested subsets of the species in larger communities. In the vast majority of studies, the question of nested subsets has been addressed using information on presence-absence, where a '0' is interpreted as the absence of a given species from a given location. Most of the methodological discussion in earlier studies investigating nestedness concerns the approach to generation of model-based matrices. However, it is most likely that in many situations investigators cannot detect all the species present in the location sampled. The possibility that zeros in incidence matrices reflect nondetection rather than absence of species has not been considered in studies addressing nested subsets, even though the position of zeros in these matrices forms the basis of earlier inference methods. These sampling artifacts are likely to lead to erroneous conclusions about both variation over space in species richness and the degree of similarity of the various locations. Here we propose an approach to investigation of nestedness, based on statistical inference methods explicitly incorporating species detection probability, that take into account the probabilistic nature of the sampling process. We use presence-absence data collected under Pollock?s robust capture-recapture design, and resort to an estimator of species richness originally developed for closed populations to assess the proportion of species shared by different locations. We develop testable predictions corresponding to the null hypothesis of a nonnested pattern, and an alternative hypothesis of perfect nestedness. We also present an index for assessing the degree of nestedness of a system of ecological communities. We illustrate our approach using avian data from the North American Breeding Bird Survey collected in Florida Keys.

Management of western coniferous forest habitat for nesting accipiter hawks

Treesearch

Richard T. Reynolds

1983-01-01

Availability of nesting sites can limit accipiter populations. Because accipiters nest in dense forest stands, any alteration that opens these stands is likely to lessen their desirability as nest sites. Tree growth and the associated changes in the vegetative structure of aging nest sites limit the number of years sites will be suitable. Therefore, prospective...

A kriging metamodel-assisted robust optimization method based on a reverse model

NASA Astrophysics Data System (ADS)

Zhou, Hui; Zhou, Qi; Liu, Congwei; Zhou, Taotao

2018-02-01

The goal of robust optimization methods is to obtain a solution that is both optimum and relatively insensitive to uncertainty factors. Most existing robust optimization approaches use outer-inner nested optimization structures where a large amount of computational effort is required because the robustness of each candidate solution delivered from the outer level should be evaluated in the inner level. In this article, a kriging metamodel-assisted robust optimization method based on a reverse model (K-RMRO) is first proposed, in which the nested optimization structure is reduced into a single-loop optimization structure to ease the computational burden. Ignoring the interpolation uncertainties from kriging, K-RMRO may yield non-robust optima. Hence, an improved kriging-assisted robust optimization method based on a reverse model (IK-RMRO) is presented to take the interpolation uncertainty of kriging metamodel into consideration. In IK-RMRO, an objective switching criterion is introduced to determine whether the inner level robust optimization or the kriging metamodel replacement should be used to evaluate the robustness of design alternatives. The proposed criterion is developed according to whether or not the robust status of the individual can be changed because of the interpolation uncertainties from the kriging metamodel. Numerical and engineering cases are used to demonstrate the applicability and efficiency of the proposed approach.

Management of livestock to improve and maintain prairie chicken habitat on the Sheyenne National Grasslands

Treesearch

Robert L. Eng; John E. Toepfer; Jay A. Newell

1988-01-01

Cover requirements of prairie grouse are primarily related to vegetative structure, whereas food needs are species related. Seasonal distribution and intensity of grazing initially alter the structure and ultimately can alter species composition. Initial successful nests were found in areas of more and higher residual cover than unsuccessful nests. Nesting areas were...

A demonstration of nesting in two antarctic icefish (genus Chionodraco) using a fin dimorphism analysis and ex situ videos.

PubMed

Ferrando, Sara; Castellano, Laura; Gallus, Lorenzo; Ghigliotti, Laura; Masini, Maria Angela; Pisano, Eva; Vacchi, Marino

2014-01-01

Visual observations and videos of Chionodraco hamatus icefish at the "Acquario di Genova" and histological analyses of congeneric species C. hamatus and C. rastrospinosus adults sampled in the field provided new anatomical and behavioral information on the reproductive biology of these white blooded species that are endemic to the High-Antarctic region. During the reproductive season, mature males of both species, which are different from females and immature males, display fleshy, club-like knob modifications of their anal fin that consisted of a much thicker epithelium. Histology indicated that the knobs were without any specialized glandular or sensorial organization, thus suggesting a mechanical and/or ornamental role of the modified anal fin. In addition, the occurrence of necrotic regions at the base of the thickened epithelium and the detachment of the knobs in post-spawning C. hamatus males indicated the temporary nature of the knobs. The role of these structures was confirmed as mechanical and was clarified using visual observations and videos of the behavior of two C. hamatus during a reproductive event that occurred in an exhibit tank at the "Acquario di Genova". The reproductive process included pre-spawning activity, preparation of the nest, egg guarding and successfully ended with egg hatching. When the spawning event approached, the male prepared the nest. The nest was constructed on an accurately selected bottom surface, which was flattened and maintained free from sand or debris by a combination of radial body movements and continuous anal fin sweeping, thus demonstrating the important mechanical/abrasive function of the anal fin knobs. The present data are the first records of active nesting in icefish and clarify the meaning of dimorphic temporary structures, whose function would have been difficult to obtain in the field.

Assessment of predation risk through referential communication in incubating birds

NASA Astrophysics Data System (ADS)

Suzuki, Toshitaka N.

2015-05-01

Parents of many bird species produce alarm calls when they approach and deter a nest predator in order to defend their offspring. Alarm calls have been shown to warn nestlings about predatory threats, but parents also face a similar risk of predation when incubating eggs in their nests. Here, I show that incubating female Japanese great tits, Parus minor, assess predation risk by conspecific alarm calls given outside the nest cavity. Tits produce acoustically discrete alarm calls for different nest predators: “jar” calls for snakes and “chicka” calls for other predators such as crows and martens. Playback experiments revealed that incubating females responded to “jar” calls by leaving their nest, whereas they responded to “chicka” calls by looking out of the nest entrance. Since snakes invade the nest cavity, escaping from the nest helps females avoid snake predation. In contrast, “chicka” calls are used for a variety of predator types, and therefore, looking out of the nest entrance helps females gather information about the type and location of approaching predators. These results show that incubating females derive information about predator type from different types of alarm calls, providing a novel example of functionally referential communication.

Assessment of predation risk through referential communication in incubating birds.

PubMed

Suzuki, Toshitaka N

2015-05-18

Parents of many bird species produce alarm calls when they approach and deter a nest predator in order to defend their offspring. Alarm calls have been shown to warn nestlings about predatory threats, but parents also face a similar risk of predation when incubating eggs in their nests. Here, I show that incubating female Japanese great tits, Parus minor, assess predation risk by conspecific alarm calls given outside the nest cavity. Tits produce acoustically discrete alarm calls for different nest predators: "jar" calls for snakes and "chicka" calls for other predators such as crows and martens. Playback experiments revealed that incubating females responded to "jar" calls by leaving their nest, whereas they responded to "chicka" calls by looking out of the nest entrance. Since snakes invade the nest cavity, escaping from the nest helps females avoid snake predation. In contrast, "chicka" calls are used for a variety of predator types, and therefore, looking out of the nest entrance helps females gather information about the type and location of approaching predators. These results show that incubating females derive information about predator type from different types of alarm calls, providing a novel example of functionally referential communication.

[Effect of landscape change on the structure of the sting-less bee community (Hymenoptera: Apidae) in Meta, Colombia].

PubMed

Nates-Parra, Guiomar; Palacios, Eliana; Parra-H, Alejandro

2008-09-01

Stingless bees represent one of the most diversified components of the natural Apoidea fauna of pollinators in the tropics. They use diverse kinds of substrates and inhabit varied habitats. Some species are typical for some natural either artificial place. The landscape alteration were this group of bees nests, has and important impact on the natural composition of its community structure, fact which is reflected in the nest density. We analyzed the structure composition of the stingless bees' community in three environments in the Colombian Ilanos piedmont, an important region that represents the transition between Andean ecosystems and a savannah that is seriously threatened by cattle practices. We made systematic samples in secondary forest, agro-ecosystems and urban areas, recording the presence of 204 nests from 11 genera (24 species). The nest density per landscape was heterogeneous and never higher than 16 nests/Ha. We observed two nesting patterns and an effect of sampling criterion on the measured biodiversity.

Computing and software

USGS Publications Warehouse

White, Gary C.; Hines, J.E.

2004-01-01

The reality is that the statistical methods used for analysis of data depend upon the availability of software. Analysis of marked animal data is no different than the rest of the statistical field. The methods used for analysis are those that are available in reliable software packages. Thus, the critical importance of having reliable, up–to–date software available to biologists is obvious. Statisticians have continued to develop more robust models, ever expanding the suite of potential analysis methodsavailable. But without software to implement these newer methods, they will languish in the abstract, and not be applied to the problems deserving them.In the Computers and Software Session, two new software packages are described, a comparison of implementation of methods for the estimation of nest survival is provided, and a more speculative paper about how the next generation of software might be structured is presented.Rotella et al. (2004) compare nest survival estimation with different software packages: SAS logistic regression, SAS non–linear mixed models, and Program MARK. Nests are assumed to be visited at various, possibly infrequent, intervals. All of the approaches described compute nest survival with the same likelihood, and require that the age of the nest is known to account for nests that eventually hatch. However, each approach offers advantages and disadvantages, explored by Rotella et al. (2004).Efford et al. (2004) present a new software package called DENSITY. The package computes population abundance and density from trapping arrays and other detection methods with a new and unique approach. DENSITY represents the first major addition to the analysis of trapping arrays in 20 years.Barker & White (2004) discuss how existing software such as Program MARK require that each new model’s likelihood must be programmed specifically for that model. They wishfully think that future software might allow the user to combine pieces of likelihood functions together to generate estimates. The idea is interesting, and maybe some bright young statistician can work out the specifics to implement the procedure.Choquet et al. (2004) describe MSURGE, a software package that implements the multistate capture–recapture models. The unique feature of MSURGE is that the design matrix is constructed with an interpreted language called GEMACO. Because MSURGE is limited to just multistate models, the special requirements of these likelihoods can be provided.The software and methods presented in these papers gives biologists and wildlife managers an expanding range of possibilities for data analysis. Although ease–of–use is generally getting better, it does not replace the need for understanding of the requirements and structure of the models being computed. The internet provides access to many free software packages as well as user–discussion groups to share knowledge and ideas. (A starting point for wildlife–related applications is (http://www.phidot.org).

Teaching Mathematics Problem Solving to Students with Limited English Proficiency through Nested Spiral Approach.

ERIC Educational Resources Information Center

Chyu, Chi-Oy W.

The Nested Spiral Approach (NSA) is an integrated instructional approach used to promote the motivated learning of mathematics problem solving in limited-English-proficient (LEP) students. The NSA is described and a trial use is discussed. The approach extends, elaborates, and supplements existing education and instruction theories to help LEP…

Age-specific productivity and nest site characteristics of Cooper's hawks (Accipiter cooperii)

USGS Publications Warehouse

Moore, K.R.; Henny, C.J.

1984-01-01

Nesting Cooper's Hawks (Accipiter cooperii) were studied in northeastern Oregon. Second-year (SY) males did not breed, but 22 percent of the breeding females were SY's. Mean clutch size (P = 0.012) and mean number of young fledged per pair that laid eggs (P < 0.10) were lower for SY females than for adult (after second year [ASY}) females; however, an equal percentage of the eggs (excluding a collected sample egg) yielded fledged young for each age class. Stepwise discriminant analysis suggested differences in structural characteristics of the nest site habitat for ASY and SY females, i.e., SY female nest sites were associated with younger successional stages than ASY female nest sites. Nests of both age groups were built in trees with high crown volume, but ASY females utilized mistletoe (Arceuthobium sp.) for nest structures more frequently (P < 0.01) than SY females.

Oviduct modifications in foam-nesting frogs, with emphasis on the genus Leptodactylus (Amphibia, Leptodactylidae)

USGS Publications Warehouse

Furness, Andrew I.; McDiarmid, Roy W.; Heyer, W. Ronald; Zug, George R.

2010-01-01

Various species of frogs produce foam nests that hold their eggs during development. We examined the external morphology and histology of structures associated with foam nest production in frogs of the genus Leptodactylus and a few other taxa. We found that the posterior convolutions of the oviducts in all mature female foam-nesting frogs that we examined were enlarged and compressed into globular structures. This organ-like portion of the oviduct has been called a "foam gland" and these structures almost certainly produce the secretion that is beaten by rhythmic limb movements into foam that forms the nest. However, the label "foam gland" is a misnomer because the structures are simply enlarged and tightly folded regions of the pars convoluta of the oviduct, rather than a separate structure; we suggest the name pars convoluta dilata (PCD) for this feature. Although all the foam-nesters we examined had a pars convoluta dilata, its size and shape showed considerable interspecific variation. Some of this variation likely reflects differences in the breeding behaviors among species and in the size, type, and placement of their foam nests. Other variation, particularly in size, may be associated with the physiological periodicity and reproductive state of the female, her age, and/or the number of times she has laid eggs.

Oh sister, where art thou? Spatial population structure and the evolution of an altruistic defence trait.

PubMed

Pamminger, T; Foitzik, S; Metzler, D; Pennings, P S

2014-11-01

The evolution of parasite virulence and host defences is affected by population structure. This effect has been confirmed in studies focusing on large spatial scales, whereas the importance of local structure is not well understood. Slavemaking ants are social parasites that exploit workers of another species to rear their offspring. Enslaved workers of the host species Temnothorax longispinosus have been found to exhibit an effective post-enslavement defence behaviour: enslaved workers were observed killing a large proportion of the parasites' offspring. As enslaved workers do not reproduce, they gain no direct fitness benefit from this 'rebellion' behaviour. However, there may be an indirect benefit: neighbouring host nests that are related to 'rebel' nests can benefit from a reduced raiding pressure, as a result of the reduction in parasite nest size due to the enslaved workers' killing behaviour. We use a simple mathematical model to examine whether the small-scale population structure of the host species could explain the evolution of this potentially altruistic defence trait against slavemaking ants. We find that this is the case if enslaved host workers are related to nearby host nests. In a population genetic study, we confirm that enslaved workers are, indeed, more closely related to host nests within the raiding range of their resident slavemaker nest, than to host nests outside the raiding range. This small-scale population structure seems to be a result of polydomy (e.g. the occupation of several nests in close proximity by a single colony) and could have enabled the evolution of 'rebellion' by kin selection. © 2014 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

Nonhydrostatic nested climate modeling: A case study of the 2010 summer season over the western United States

NASA Astrophysics Data System (ADS)

Lebassi-Habtezion, Bereket; Diffenbaugh, Noah S.

2013-10-01

potential importance of local-scale climate phenomena motivates development of approaches to enable computationally feasible nonhydrostatic climate simulations. To that end, we evaluate the potential viability of nested nonhydrostatic model approaches, using the summer climate of the western United States (WUSA) as a case study. We use the Weather Research and Forecast (WRF) model to carry out five simulations of summer 2010. This suite allows us to test differences between nonhydrostatic and hydrostatic resolutions, single and multiple nesting approaches, and high- and low-resolution reanalysis boundary conditions. WRF simulations were evaluated against station observations, gridded observations, and reanalysis data over domains that cover the 11 WUSA states at nonhydrostatic grid spacing of 4 km and hydrostatic grid spacing of 25 km and 50 km. Results show that the nonhydrostatic simulations more accurately resolve the heterogeneity of surface temperature, precipitation, and wind speed features associated with the topography and orography of the WUSA region. In addition, we find that the simulation in which the nonhydrostatic grid is nested directly within the regional reanalysis exhibits the greatest overall agreement with observational data. Results therefore indicate that further development of nonhydrostatic nesting approaches is likely to yield important insights into the response of local-scale climate phenomena to increases in global greenhouse gas concentrations. However, the biases in regional precipitation, atmospheric circulation, and moisture flux identified in a subset of the nonhydrostatic simulations suggest that alternative nonhydrostatic modeling approaches such as superparameterization and variable-resolution global nonhydrostatic modeling will provide important complements to the nested approaches tested here.

Arboreal nesting as anti-predator adaptation by savanna chimpanzees (Pan troglodytes verus) in southeastern Senegal.

PubMed

Pruetz, J D; Fulton, S J; Marchant, L F; McGrew, W C; Schiel, M; Waller, M

2008-04-01

Chimpanzees (Pan troglodytes) make nests for resting and sleeping, which is unusual for anthropoid primates but common to all great apes. Arboreal nesting has been linked to predation pressure, but few studies have tested the adaptive nature of this behavior. We collected data at two chimpanzee study sites in southeastern Senegal that differed in predator presence to test the hypothesis that elevated sleeping platforms are adaptations for predator defense. At Assirik in the Parc National du Niokolo-Koba, chimpanzees face four species of large carnivore, whereas at Fongoli, outside national park boundaries, humans have exterminated almost all natural predators. We quantified the availability of vegetation at the two sites to test the alternative hypothesis that differences in nesting reflect differences in habitat structure. We also examined possible sex differences in nesting behavior, community demographic differences, seasonality and nest age differences as variables also potentially affecting nest characteristics and nesting behavior between the two sites. Chimpanzees at Fongoli nested at lower heights and farther apart than did chimpanzees at Assirik and sometimes made nests on the ground. The absence of predators outside of the national park may account for the differences in nest characteristics at the two sites, given the similarities in habitat structure between Fongoli and Assirik. However, Fongoli chimpanzees regularly build arboreal nests for sleeping, even under minimal predation pressure, and this requires explanation.

Relationships of surrounding riparian habitat to nest-box use and reproductive outcome in House Wrens

Treesearch

Deborah M. Finch

1989-01-01

I assessed relationships among habitat structure, nest-site selection, and reproductive outcome of House Wrens (Troglodytes aedon) by establishing three nest-box grids in riparian woodlands in southeastern Wyoming. Over a 3-year period, 37% of the boxes contained House Wren nests; 20% contained unused nests built by male House Wrens; and 42% were never used by wrens....

A Hierarchical Modeling Approach to Data Analysis and Study Design in a Multi-Site Experimental fMRI Study

ERIC Educational Resources Information Center

Zhou, Bo; Konstorum, Anna; Duong, Thao; Tieu, Kinh H.; Wells, William M.; Brown, Gregory G.; Stern, Hal S.; Shahbaba, Babak

2013-01-01

We propose a hierarchical Bayesian model for analyzing multi-site experimental fMRI studies. Our method takes the hierarchical structure of the data (subjects are nested within sites, and there are multiple observations per subject) into account and allows for modeling between-site variation. Using posterior predictive model checking and model…

Parameter Recovery for the 1-P HGLLM with Non-Normally Distributed Level-3 Residuals

ERIC Educational Resources Information Center

Kara, Yusuf; Kamata, Akihito

2017-01-01

A multilevel Rasch model using a hierarchical generalized linear model is one approach to multilevel item response theory (IRT) modeling and is referred to as a one-parameter hierarchical generalized linear logistic model (1-P HGLLM). Although it has the flexibility to model nested structure of data with covariates, the model assumes the normality…

Use of the superpopulation approach to estimate breeding population size: An example in asynchronously breeding birds

USGS Publications Warehouse

Williams, K.A.; Frederick, P.C.; Nichols, J.D.

2011-01-01

Many populations of animals are fluid in both space and time, making estimation of numbers difficult. Much attention has been devoted to estimation of bias in detection of animals that are present at the time of survey. However, an equally important problem is estimation of population size when all animals are not present on all survey occasions. Here, we showcase use of the superpopulation approach to capture-recapture modeling for estimating populations where group membership is asynchronous, and where considerable overlap in group membership among sampling occasions may occur. We estimate total population size of long-legged wading bird (Great Egret and White Ibis) breeding colonies from aerial observations of individually identifiable nests at various times in the nesting season. Initiation and termination of nests were analogous to entry and departure from a population. Estimates using the superpopulation approach were 47-382% larger than peak aerial counts of the same colonies. Our results indicate that the use of the superpopulation approach to model nesting asynchrony provides a considerably less biased and more efficient estimate of nesting activity than traditional methods. We suggest that this approach may also be used to derive population estimates in a variety of situations where group membership is fluid. ?? 2011 by the Ecological Society of America.

Factors affecting songbird nest survival in riparian forests in a Midwestern agricultural landscape

Treesearch

Rebecca G. Peak; Frank R. Thompson; Terry L. Shaffer

2004-01-01

We investigated factors affecting nest success of songbirds in riparian forest and buffers in northeastern Missouri. We used an information-theoretic approach to determine support for hypotheses concerning effects of nest-site, habitat-patch, edge, and temporal factors on nest success of songbirds in three narrow (55-95 m) and three wide (400-530 m) riparian forests...

Does habitat fragmentation influence nest predation in the shortgrass prairie?

USGS Publications Warehouse

Howard, M.N.; Skagen, S.K.; Kennedy, P.L.

2001-01-01

We examined the effects of habitat fragmentation and vegetation structure of shortgrass prairie and Conservation Reserve Program (CRP) lands on predation rates of artificial and natural nests in northeastern Colorado. The CRP provides federal payments to landowners to take highly erodible cropland out of agricultural production. In our study area, CRP lands have been reseeded primarily with non-native grasses, and this vegetation is taller than native shortgrass prairie. We measured three indices of habitat fragmentation (patch size, degree of matrix fragmentation, and distance from edge), none of which influenced mortality rates of artificial or natural nests. Vegetation structure did influence predation rates of artificial nests; daily mortality decreased significantly with increasing vegetation height. Vegetation structure did not influence predation rates of natural nests. CRP lands and shortgrass sites did not differ with respect to mortality rates of artificial nests. Our study area is only moderately fragmented; 62% of the study area is occupied by native grassland. We conclude that the extent of habitat fragmentation in our study area does not result in increased predation in remaining patches of shortgrass prairie habitat.

Molecular forensics in avian conservation: a DNA-based approach for identifying mammalian predators of ground-nesting birds and eggs.

PubMed

Hopken, Matthew W; Orning, Elizabeth K; Young, Julie K; Piaggio, Antoinette J

2016-01-07

The greater sage-grouse (Centrocercus urophasianus) is a ground-nesting bird from the Northern Rocky Mountains and a species at risk of extinction in in multiple U.S. states and Canada. Herein we report results from a proof of concept that mitochondrial and nuclear DNAs from mammalian predator saliva could be non-invasively collected from depredated greater sage-grouse eggshells and carcasses and used for predator species identification. Molecular forensic approaches have been applied to identify predators from depredated remains as one strategy to better understand predator-prey dynamics and guide management strategies. This can aid conservation efforts by correctly identifying predators most likely to impact threatened and endangered species. DNA isolated from non-invasive samples around nesting sites (e.g. fecal or hair samples) is one method that can increase the success and accuracy of predator species identification when compared to relying on nest remains alone. Predator saliva DNA was collected from depredated eggshells and carcasses using swabs. We sequenced two partial fragments of two mitochondrial genes and obtained microsatellite genotypes using canid specific primers for species and individual identification, respectively. Using this multilocus approach we were able to identify predators, at least down to family, from 11 out of 14 nests (79%) and three out of seven carcasses (47%). Predators detected most frequently were canids (86%), while other taxa included rodents, a striped skunk, and cattle. We attempted to match the genotypes of individual coyotes obtained from eggshells and carcasses with those obtained from fecal samples and coyotes collected in the areas, but no genotype matches were found. Predation is a main cause of nest failure in ground-nesting birds and can impact reproduction and recruitment. To inform predator management for ground-nesting bird conservation, accurate identification of predator species is necessary. Considering predation can have a high impact on recruitment, predation events are very difficult to observe, and predator species are difficult to identify visually from nest remains, molecular approaches that reduce the need to observe or handle animals offer an additional tool to better understand predator-prey dynamics at nesting sites.

Cavity Nesting Birds

Treesearch

Virgil E. Scott; Keith E. Evans; David R. Patton; Charles P. Stone

1977-01-01

Many species of cavity-nesting birds have declined because of habitat reduction. In the eastern United States, where primeval forests are gone, purple martins depend almost entirely on man-made nesting structures (Allen and Nice 1952). The hole-nesting population of peregrine falcons disappeared with the felling of the giant trees upon which they depended (Hickey and...

Voluntary Nonmonetary Conservation Approaches on Private Land: A Review of Constraints, Risks, and Benefits for Raptor Nest Protection

NASA Astrophysics Data System (ADS)

Santangeli, Andrea; Laaksonen, Toni

2015-02-01

Biodiversity conservation on private land of the developed world faces several challenges. The costs of land are often high, and the attitudes of landowners towards conservation are variable. Scientists and practitioners need to scan for and adopt cost-effective solutions that allow for the long-term sustainability of conservation measures on private land. In this study, we focus on one of such possible solutions: Working with landowners to implement voluntary nonmonetary conservation. We restrict our focus to protection of raptor nests, but the ideas can be applied to other taxa as well. Through a literature review, we show that a voluntary nonmonetary approach for protecting raptor nests has been so far largely neglected and/or rarely reported in the scientific literature. However, results of a questionnaire sent to BirdLife partners across Europe indicate that this approach is more widely used than it appears from the literature. We show that voluntary nonmonetary approaches may represent useful tools to protect raptor nests on private land. We provide a workflow for implementation of such an approach in raptor nest protection, highlighting benefits, potential risks, and constraints in the application of the strategy. We suggest that a voluntary nonmonetary approach may have great potential for cost-effective conservation, but the risks it may entail should be carefully assessed in each case. There is an urgent need to consider and evaluate novel approaches, such as the one described here, which may constitute missed opportunities for cost-effective conservation.

Characteristics of nest trees and nest sites of California spotted owls in coniferous forests of the southern Sierra Nevada

Treesearch

George N. Steger; Thomas E. Munton; Kenneth D. Johnson; Gary E. Eberlein

1997-01-01

We described 86 nest sites of California spotted owl (Sh-ix occidentalis occrdentalzs) and tested for differences in vegetation structure at nest locations rn conifer-dominated stands in 2 study areas, the Sierra National Forest (SNF) and Sequoia and Kings Canyon National Parks (SNP), California. All nests were between 1061 and 2414 m in elevation, 52 were side-cavity...

Teaching Science to Students with Limited English Proficiency through Nested Spiral Approach.

ERIC Educational Resources Information Center

Chyu, Chi-oy W.

The Nested Spiral Approach (NSA) is a teaching technique designed for students of limited English proficiency that integrates four aspects of motivated learning: contents, language, culture, and real life experiences. The approach consists of: (1) effective use of student strengths; (2) three teaching cycles for each lesson; and (3) five steps in…

Nest suitability, fine-scale population structure and male-mediated dispersal of a solitary ground nesting bee in an urban landscape.

PubMed

López-Uribe, Margarita M; Morreale, Stephen J; Santiago, Christine K; Danforth, Bryan N

2015-01-01

Bees are the primary pollinators of flowering plants in almost all ecosystems. Worldwide declines in bee populations have raised awareness about the importance of their ecological role in maintaining ecosystem functioning. The naturally strong philopatric behavior that some bee species show can be detrimental to population viability through increased probability of inbreeding. Furthermore, bee populations found in human-altered landscapes, such as urban areas, can experience lower levels of gene flow and effective population sizes, increasing potential for inbreeding depression in wild bee populations. In this study, we investigated the fine-scale population structure of the solitary bee Colletes inaequalis in an urbanized landscape. First, we developed a predictive spatial model to detect suitable nesting habitat for this ground nesting bee and to inform our field search for nests. We genotyped 18 microsatellites in 548 female individuals collected from nest aggregations throughout the study area. Genetic relatedness estimates revealed that genetic similarity among individuals was slightly greater within nest aggregations than among randomly chosen individuals. However, genetic structure among nest aggregations was low (Nei's GST = 0.011). Reconstruction of parental genotypes revealed greater genetic relatedness among females than among males within nest aggregations, suggesting male-mediated dispersal as a potentially important mechanism of population connectivity and inbreeding avoidance. Size of nesting patch was positively correlated with effective population size, but not with other estimators of genetic diversity. We detected a positive trend between geographic distance and genetic differentiation between nest aggregations. Our landscape genetic models suggest that increased urbanization is likely associated with higher levels of inbreeding. Overall, these findings emphasize the importance of density and distribution of suitable nesting patches for enhancing bee population abundance and connectivity in human dominated habitats and highlights the critical contribution of landscape genetic studies for enhanced conservation and management of native pollinators.

Nest Suitability, Fine-Scale Population Structure and Male-Mediated Dispersal of a Solitary Ground Nesting Bee in an Urban Landscape

PubMed Central

López-Uribe, Margarita M.; Morreale, Stephen J.; Santiago, Christine K.; Danforth, Bryan N.

2015-01-01

Bees are the primary pollinators of flowering plants in almost all ecosystems. Worldwide declines in bee populations have raised awareness about the importance of their ecological role in maintaining ecosystem functioning. The naturally strong philopatric behavior that some bee species show can be detrimental to population viability through increased probability of inbreeding. Furthermore, bee populations found in human-altered landscapes, such as urban areas, can experience lower levels of gene flow and effective population sizes, increasing potential for inbreeding depression in wild bee populations. In this study, we investigated the fine-scale population structure of the solitary bee Colletes inaequalis in an urbanized landscape. First, we developed a predictive spatial model to detect suitable nesting habitat for this ground nesting bee and to inform our field search for nests. We genotyped 18 microsatellites in 548 female individuals collected from nest aggregations throughout the study area. Genetic relatedness estimates revealed that genetic similarity among individuals was slightly greater within nest aggregations than among randomly chosen individuals. However, genetic structure among nest aggregations was low (Nei’s GST = 0.011). Reconstruction of parental genotypes revealed greater genetic relatedness among females than among males within nest aggregations, suggesting male-mediated dispersal as a potentially important mechanism of population connectivity and inbreeding avoidance. Size of nesting patch was positively correlated with effective population size, but not with other estimators of genetic diversity. We detected a positive trend between geographic distance and genetic differentiation between nest aggregations. Our landscape genetic models suggest that increased urbanization is likely associated with higher levels of inbreeding. Overall, these findings emphasize the importance of density and distribution of suitable nesting patches for enhancing bee population abundance and connectivity in human dominated habitats and highlights the critical contribution of landscape genetic studies for enhanced conservation and management of native pollinators. PMID:25950429

Statistical Significance for Hierarchical Clustering

PubMed Central

Kimes, Patrick K.; Liu, Yufeng; Hayes, D. Neil; Marron, J. S.

2017-01-01

Summary Cluster analysis has proved to be an invaluable tool for the exploratory and unsupervised analysis of high dimensional datasets. Among methods for clustering, hierarchical approaches have enjoyed substantial popularity in genomics and other fields for their ability to simultaneously uncover multiple layers of clustering structure. A critical and challenging question in cluster analysis is whether the identified clusters represent important underlying structure or are artifacts of natural sampling variation. Few approaches have been proposed for addressing this problem in the context of hierarchical clustering, for which the problem is further complicated by the natural tree structure of the partition, and the multiplicity of tests required to parse the layers of nested clusters. In this paper, we propose a Monte Carlo based approach for testing statistical significance in hierarchical clustering which addresses these issues. The approach is implemented as a sequential testing procedure guaranteeing control of the family-wise error rate. Theoretical justification is provided for our approach, and its power to detect true clustering structure is illustrated through several simulation studies and applications to two cancer gene expression datasets. PMID:28099990

Migratory patterns and population structure among breeding and wintering red-breasted mergansers (Mergus serrator) and common mergansers (M. merganser)

USGS Publications Warehouse

Pearce, J.M.; McCracken, K.G.; Christensen, Thomas K.; Zhuravlev, Y.N.

2009-01-01

Philopatry has long been assumed to structure populations of waterfowl and other species of birds genetically, especially via maternally transmitted mitochondrial DNA (mtDNA), yet other migratory behaviors and nesting ecology (use of ground vs. cavity sites) may also contribute to population genetic structure. We investigated the effects of migration and nesting ecology on the population genetic structure of two Holarctic waterfowl, the Red-breasted Merganser (Mergus serrator) and Common Merganser (M. merganser), using mtDNA control-region sequence data. Red-breasted Mergansers (a ground-nesting species) exhibited lower levels of population differentiation across their North American range, possibly as a result of post-Pleistocene range expansion and population growth. By contrast, Common Mergansers (a cavity-nesting species) breeding in western and eastern North America were strongly differentiated, as were continental groups in North America and Europe. Our hypothesis that population differentiation of breeding female Common Mergansers results from limited migration during non-breeding periods was not supported, in that equally heterogeneous mtDNA lineages were observed in males and females on several wintering areas. The interspecific differences in mtDNA patterns for these two closely related species may have resulted from factors related to nesting ecology (ground vs. cavity nesting) and responses to historical climate change.

Biomimetic Ant-Nest Electrode Structures for High Sulfur Ratio Lithium–Sulfur Batteries

DOE PAGES

Ai, Guo; Dai, Yiling; Mao, Wenfeng; ...

2016-08-08

The lithium–sulfur (Li–S) rechargeable battery has the benefit of high gravimetric energy density and low cost. Significant research currently focuses on increasing the sulfur loading and sulfur/inactive-materials ratio, to improve life and capacity. Inspired by nature’s ant-nest structure, this study results in a novel Li–S electrode that is designed to meet both goals. With only three simple manufacturing-friendly steps, which include slurry ball-milling, doctor-blade-based laminate casting, and the use of the sacrificial method with water to dissolve away table salt, the ant-nest design has been successfully recreated in an Li–S electrode. The efficient capabilities of the ant-nest structure are adoptedmore » to facilitate fast ion transportation, sustain polysulfide dissolution, and assist efficient precipitation. Finally, high cycling stability in the Li–S batteries, for practical applications, has been achieved with up to 3 mg·cm –2 sulfur loading. Li–S electrodes with up to a 85% sulfur ratio have also been achieved for the efficient design of this novel ant-nest structure.« less

Bird nesting and droppings control on highway structures.

DOT National Transportation Integrated Search

2010-10-01

This report provides a comprehensive literature survey of permanent and temporary deterrents to nesting and roosting, a : discussion of risks to human health and safety from exposure to bird nests and droppings and recommended protective measures, : ...

A Minimally Invasive Method for Sampling Nest and Roost Cavities for Fungi: a Novel Approach to Identify the Fungi Associated with Cavity-Nesting Birds

Treesearch

Michelle A. Jusino; Daniel Lindner; John K. Cianchetti; Adam T. Grisé; Nicholas J. Brazee; Jeffrey R. Walters

2014-01-01

Relationships among cavity-nesting birds, trees, and wood decay fungi pose interesting management challenges and research questions in many systems. Ornithologists need to understand the relationships between cavity-nesting birds and fungi in order to understand the habitat requirements of these birds. Typically, researchers rely on fruiting body surveys to identify...

Habitat structure mediates predation risk for sedentary prey: Experimental tests of alternative hypotheses

USGS Publications Warehouse

Chalfoun, A.D.; Martin, T.E.

2009-01-01

Predation is an important and ubiquitous selective force that can shape habitat preferences of prey species, but tests of alternative mechanistic hypotheses of habitat influences on predation risk are lacking. 2. We studied predation risk at nest sites of a passerine bird and tested two hypotheses based on theories of predator foraging behaviour. The total-foliage hypothesis predicts that predation will decline in areas of greater overall vegetation density by impeding cues for detection by predators. The potential-prey-site hypothesis predicts that predation decreases where predators must search more unoccupied potential nest sites. 3. Both observational data and results from a habitat manipulation provided clear support for the potential-prey-site hypothesis and rejection of the total-foliage hypothesis. Birds chose nest patches containing both greater total foliage and potential nest site density (which were correlated in their abundance) than at random sites, yet only potential nest site density significantly influenced nest predation risk. 4. Our results therefore provided a clear and rare example of adaptive nest site selection that would have been missed had structural complexity or total vegetation density been considered alone. 5. Our results also demonstrated that interactions between predator foraging success and habitat structure can be more complex than simple impedance or occlusion by vegetation. ?? 2008 British Ecological Society.

Factors influencing depredation of artificial duck nests

USGS Publications Warehouse

Esler, Daniel N.; Grand, James B.

1993-01-01

Because artificial nests can facilitate controlled experiments of nest success, we used them to assess whether human visitation, nest density, vegetation structure, and proximity to habitat edge could affect depredation of duck nests on Yukon Flats National Wildlife Refuge, Alaska. More (P < 0.01) nests in a plot visited daily (100%) were depredated than those in plots visited at intervals of 7 (40%), 14 (35%), or 28 days (45%). More (P < 0.01) nests were depredated in a plot with 10 nests/ha (95%) than nests in a plot of a lower density (2/ha; 40%). Vegetation height, vegetation density, distance to a wetland, distance to forest edge, or distance to the nearest ecotone did not differ (P > 0.05) between depredated and undisturbed nests. We suggest that daily visitation of duck nests increases depredation, but longer intervals, typical of most nest studies, do not. High nesting densities, which could occur when flooding limits nesting habitat, may result in higher depredation rates.

MIMICKING COUNTERFACTUAL OUTCOMES TO ESTIMATE CAUSAL EFFECTS.

PubMed

Lok, Judith J

2017-04-01

In observational studies, treatment may be adapted to covariates at several times without a fixed protocol, in continuous time. Treatment influences covariates, which influence treatment, which influences covariates, and so on. Then even time-dependent Cox-models cannot be used to estimate the net treatment effect. Structural nested models have been applied in this setting. Structural nested models are based on counterfactuals: the outcome a person would have had had treatment been withheld after a certain time. Previous work on continuous-time structural nested models assumes that counterfactuals depend deterministically on observed data, while conjecturing that this assumption can be relaxed. This article proves that one can mimic counterfactuals by constructing random variables, solutions to a differential equation, that have the same distribution as the counterfactuals, even given past observed data. These "mimicking" variables can be used to estimate the parameters of structural nested models without assuming the treatment effect to be deterministic.

Evaluating nest supplementation as a recovery strategy for the endangered rodents of the Florida Keys

USGS Publications Warehouse

Cove, Michael V.; Simons, Theodore R.; Gardner, Beth; Maurer, Andrew S.; O'Connell, Allan F.

2017-01-01

The Key Largo woodrat (Neotoma floridana smalli) and Key Largo cotton mouse (Peromyscus gossypinus allapaticola) are federally endangered subspecies endemic to the tropical hardwood hammocks of Key Largo, Florida. Woodrats are considered generalists in habitat and diet, yet a steady decline in natural stick nests and capture rates over the past several decades suggests that they are limited by the availability of nesting habitat due to habitat loss and fragmentation. The more specialized Key Largo cotton mouse appears to rely on old growth hammock, a habitat type that is rare following past land clearing. In 2004, the U.S. Fish and Wildlife Service started building supplemental nest structures to restore habitat quality and connectivity for these endangered rodents, but nest use requires evaluation. We used camera traps and occupancy models to evaluate the factors influencing woodrat and cotton mouse use of the supplemental nests. We detected woodrats at 65 and cotton mice at 175 of 284 sampled nest structures, with co-occurrence at 38 nests. Woodrat nest use followed a gradient from low nest use in the north to high nest use in the south, which might relate to the proximity of free-ranging domestic cat (Felis catus) colonies in residential developments. Cotton mouse nest use, however, was related positively to mature hammock and related negatively to disturbed areas (e.g. scarified lands). The two species occurred independently of each other. Stick-stacking behavior was observed at supplemental nests and, although it was correlated with detection of woodrats, it was not a strong predictor of their occurrence. We suggest that nest supplementation can be an important tool for species recovery as habitat quality continues to improve with succession.

Interaction in Balanced Cross Nested Designs

NASA Astrophysics Data System (ADS)

Ramos, Paulo; Mexia, João T.; Carvalho, Francisco; Covas, Ricardo

2011-09-01

Commutative Jordan Algebras, CJA, are used in the study of mixed models obtained, through crossing and nesting, from simpler ones. In the study of cross nested models the interaction between nested factors have been systematically discarded. However this can constitutes an artificial simplification of the models. We point out that, when two crossed factors interact, such interaction is symmetric, both factors playing in it equivalent roles, while when two nested factors interact, the interaction is determined by the nesting factor. These interactions will be called interactions with nesting. In this work we present a coherent formulation of the algebraic structure of models enabling the choice of families of interactions between cross and nested factors using binary operations on CJA.

Wind Farm LES Simulations Using an Overset Methodology

NASA Astrophysics Data System (ADS)

Ananthan, Shreyas; Yellapantula, Shashank

2017-11-01

Accurate simulation of wind farm wakes under realistic atmospheric inflow conditions and complex terrain requires modeling a wide range of length and time scales. The computational domain can span several kilometers while requiring mesh resolutions in O(10-6) to adequately resolve the boundary layer on the blade surface. Overset mesh methodology offers an attractive option to address the disparate range of length scales; it allows embedding body-confirming meshes around turbine geomtries within nested wake capturing meshes of varying resolutions necessary to accurately model the inflow turbulence and the resulting wake structures. Dynamic overset hole-cutting algorithms permit relative mesh motion that allow this nested mesh structure to track unsteady inflow direction changes, turbine control changes (yaw and pitch), and wake propagation. An LES model with overset mesh for localized mesh refinement is used to analyze wind farm wakes and performance and compared with local mesh refinements using non-conformal (hanging node) unstructured meshes. Turbine structures will be modeled using both actuator line approaches and fully-resolved structures to test the efficacy of overset methods for wind farm applications. Exascale Computing Project (ECP), Project Number: 17-SC-20-SC, a collaborative effort of two DOE organizations - the Office of Science and the National Nuclear Security Administration.

Discriminating the Drivers of Edge Effects on Nest Predation: Forest Edges Reduce Capture Rates of Ship Rats (Rattus rattus), a Globally Invasive Nest Predator, by Altering Vegetation Structure

PubMed Central

Ruffell, Jay; Didham, Raphael K.; Barrett, Paul; Gorman, Nic; Pike, Rhonda; Hickey-Elliott, Andrée; Sievwright, Karin; Armstrong, Doug P.

2014-01-01

Forest edges can strongly affect avian nest success by altering nest predation rates, but this relationship is inconsistent and context dependent. There is a need for researchers to improve the predictability of edge effects on nest predation rates by examining the mechanisms driving their occurrence and variability. In this study, we examined how the capture rates of ship rats, an invasive nest predator responsible for avian declines globally, varied with distance from the forest edge within forest fragments in a pastoral landscape in New Zealand. We hypothesised that forest edges would affect capture rates by altering vegetation structure within fragments, and that the strength of edge effects would depend on whether fragments were grazed by livestock. We measured vegetation structure and rat capture rates at 488 locations ranging from 0–212 m from the forest edge in 15 forest fragments, seven of which were grazed. Contrary to the vast majority of previous studies of edge effects on nest predation, ship rat capture rates increased with increasing distance from the forest edge. For grazed fragments, capture rates were estimated to be 78% lower at the forest edge than 118 m into the forest interior (the farthest distance for grazed fragments). This relationship was similar for ungrazed fragments, with capture rates estimated to be 51% lower at the forest edge than 118 m into the forest interior. A subsequent path analysis suggested that these ‘reverse’ edge effects were largely or entirely mediated by changes in vegetation structure, implying that edge effects on ship rats can be predicted from the response of vegetation structure to forest edges. We suggest the occurrence, strength, and direction of edge effects on nest predation rates may depend on edge-driven changes in local habitat when the dominant predator is primarily restricted to forest patches. PMID:25412340

Discriminating the drivers of edge effects on nest predation: forest edges reduce capture rates of ship rats (Rattus rattus), a globally invasive nest predator, by altering vegetation structure.

PubMed

Ruffell, Jay; Didham, Raphael K; Barrett, Paul; Gorman, Nic; Pike, Rhonda; Hickey-Elliott, Andrée; Sievwright, Karin; Armstrong, Doug P

2014-01-01

Forest edges can strongly affect avian nest success by altering nest predation rates, but this relationship is inconsistent and context dependent. There is a need for researchers to improve the predictability of edge effects on nest predation rates by examining the mechanisms driving their occurrence and variability. In this study, we examined how the capture rates of ship rats, an invasive nest predator responsible for avian declines globally, varied with distance from the forest edge within forest fragments in a pastoral landscape in New Zealand. We hypothesised that forest edges would affect capture rates by altering vegetation structure within fragments, and that the strength of edge effects would depend on whether fragments were grazed by livestock. We measured vegetation structure and rat capture rates at 488 locations ranging from 0-212 m from the forest edge in 15 forest fragments, seven of which were grazed. Contrary to the vast majority of previous studies of edge effects on nest predation, ship rat capture rates increased with increasing distance from the forest edge. For grazed fragments, capture rates were estimated to be 78% lower at the forest edge than 118 m into the forest interior (the farthest distance for grazed fragments). This relationship was similar for ungrazed fragments, with capture rates estimated to be 51% lower at the forest edge than 118 m into the forest interior. A subsequent path analysis suggested that these 'reverse' edge effects were largely or entirely mediated by changes in vegetation structure, implying that edge effects on ship rats can be predicted from the response of vegetation structure to forest edges. We suggest the occurrence, strength, and direction of edge effects on nest predation rates may depend on edge-driven changes in local habitat when the dominant predator is primarily restricted to forest patches.

Territory and nest site selection patterns by Grasshopper Sparrows in southeastern Arizona

USGS Publications Warehouse

Ruth, Janet M.; Skagen, Susan K.

2017-01-01

Grassland bird populations are showing some of the greatest rates of decline of any North American birds, prompting measures to protect and improve important habitat. We assessed how vegetation structure and composition, habitat features often targeted for management, affected territory and nest site selection by Grasshopper Sparrows (Ammodramus savannarum ammolegus) in southeastern Arizona. To identify features important to males establishing territories, we compared vegetation characteristics of known territories and random samples on 2 sites over 5 years. We examined habitat selection patterns of females by comparing characteristics of nest sites with territories over 3 years. Males selected territories in areas of sparser vegetation structure and more tall shrubs (>2 m) than random plots on the site with low shrub densities. Males did not select territories based on the proportion of exotic grasses. Females generally located nest sites in areas with lower small shrub (1–2 m tall) densities than territories overall when possible and preferentially selected native grasses for nest construction. Whether habitat selection was apparent depended upon the range of vegetation structure that was available. We identified an upper threshold above which grass structure seemed to be too high and dense for Grasshopper Sparrows. Our results suggest that some management that reduces vegetative structure may benefit this species in desert grasslands at the nest and territory scale. However, we did not assess initial male habitat selection at a broader landscape scale where their selection patterns may be different and could be influenced by vegetation density and structure outside the range of values sampled in this study.

Comparative population structure of cavity-nesting sea ducks

USGS Publications Warehouse

Pearce, John M.; Eadie, John M.; Savard, Jean-Pierre L.; Christensen, Thomas K.; Berdeen, James; Taylor, Eric J.; Boyd, Sean; Einarsson, Árni

2014-01-01

A growing collection of mtDNA genetic information from waterfowl species across North America suggests that larger-bodied cavity-nesting species exhibit greater levels of population differentiation than smaller-bodied congeners. Although little is known about nest-cavity availability for these species, one hypothesis to explain differences in population structure is reduced dispersal tendency of larger-bodied cavity-nesting species due to limited abundance of large cavities. To investigate this hypothesis, we examined population structure of three cavity-nesting waterfowl species distributed across much of North America: Barrow's Goldeneye (Bucephala islandica), Common Goldeneye (B. clangula), and Bufflehead (B. albeola). We compared patterns of population structure using both variation in mtDNA control-region sequences and band-recovery data for the same species and geographic regions. Results were highly congruent between data types, showing structured population patterns for Barrow's and Common Goldeneye but not for Bufflehead. Consistent with our prediction, the smallest cavity-nesting species, the Bufflehead, exhibited the lowest level of population differentiation due to increased dispersal and gene flow. Results provide evidence for discrete Old and New World populations of Common Goldeneye and for differentiation of regional groups of both goldeneye species in Alaska, the Pacific Northwest, and the eastern coast of North America. Results presented here will aid management objectives that require an understanding of population delineation and migratory connectivity between breeding and wintering areas. Comparative studies such as this one highlight factors that may drive patterns of genetic diversity and population trends.

Assessing exotic plant species invasions and associated soil characteristics: A case study in eastern Rocky Mountain National Park, Colorado, USA, using the pixel nested plot design

USGS Publications Warehouse

Kalkhan, M.A.; Stafford, E.J.; Woodly, P.J.; Stohlgren, T.J.

2007-01-01

Rocky Mountain National Park (RMNP), Colorado, USA, contains a diversity of plant species. However, many exotic plant species have become established, potentially impacting the structure and function of native plant communities. Our goal was to quantify patterns of exotic plant species in relation to native plant species, soil characteristics, and other abiotic factors that may indicate or predict their establishment and success. Our research approach for field data collection was based on a field plot design called the pixel nested plot. The pixel nested plot provides a link to multi-phase and multi-scale spatial modeling-mapping techniques that can be used to estimate total species richness and patterns of plant diversity at finer landscape scales. Within the eastern region of RMNP, in an area of approximately 35,000 ha, we established a total of 60 pixel nested plots in 9 vegetation types. We used canonical correspondence analysis (CCA) and multiple linear regressions to quantify relationships between soil characteristics and native and exotic plant species richness and cover. We also used linear correlation, spatial autocorrelation and cross correlation statistics to test for the spatial patterns of variables of interest. CCA showed that exotic species were significantly (P < 0.05) associated with photosynthetically active radiation (r = 0.55), soil nitrogen (r = 0.58) and bare ground (r = -0.66). Pearson's correlation statistic showed significant linear relationships between exotic species, organic carbon, soil nitrogen, and bare ground. While spatial autocorrelations indicated that our 60 pixel nested plots were spatially independent, the cross correlation statistics indicated that exotic plant species were spatially associated with bare ground, in general, exotic plant species were most abundant in areas of high native species richness. This indicates that resource managers should focus on the protection of relatively rare native rich sites with little canopy cover, and fertile soils. Using the pixel nested plot approach for data collection can facilitate the ecological monitoring of these vulnerable areas at the landscape scale in a time- and cost-effective manner. ?? 2006 Elsevier B.V. All rights reserved.

Are They Really "Two Different Species?" Implicitly Elicited Student Perceptions about NESTs and NNESTs

ERIC Educational Resources Information Center

Aslan, Erhan; Thompson, Amy S.

2017-01-01

The native/nonnative-English-speaking teacher (NEST/NNEST) dichotomy has received much attention in the English language teaching profession. Although research shows that NESTs and NNESTs have different perceived strengths regarding English proficiency, personal characteristics, teaching behavior, and approaches to teaching English, more research…

Interactions between nesting pileated woodpeckers and wood ducks

Treesearch

Richard N. Conner; Clifford E. Shackelford; Daniel Saenz; Richard R. Schaefer

2001-01-01

We observed interactions between a nesting pair of pileated woodpeckers (Dryocopus pileatus) and what appeared to be four pairs of wood ducks (Aix sponsa). Wood ducks regularly approached and attempted to enter an active pileated woodpecker nest cavity that contained three fully feathered young pileated woodpeckers. The male...

Predation risk of artificial ground nests in managed floodplain meadows

NASA Astrophysics Data System (ADS)

Arbeiter, Susanne; Franke, Elisabeth

2018-01-01

Nest predation highly determines the reproductive success in birds. In agricultural grasslands, vegetation characteristics and management practices influences the predation risk of ground breeders. Little is known so far on the predation pressure on non-passerine nests in tall swards. Investigations on the interaction of land use with nesting site conditions and the habitat selection of nest predators are crucial to develop effective conservation measures for grassland birds. In this study, we used artificial nests baited with quail and plasticine eggs to identify potential predators of ground nests in floodplain meadows and related predation risk to vegetation structure and grassland management. Mean daily predation rate was 0.01 (±0.012) after an exposure duration of 21 days. 70% of all observed nest predations were caused by mammals (Red Fox and mustelids) and 17.5% by avian predators (corvids). Nest sites close to the meadow edge and those providing low forb cover were faced with a higher daily predation risk. Predation risk also increased later in the season. Land use in the preceding year had a significant effect on predation risk, showing higher predation rates on unmanaged sites than on mown sites. Unused meadows probably attract mammalian predators, because they provide a high abundance of small rodents and a more favourable vegetation structure for foraging, increasing also the risk of incidental nest predations. Although mowing operation is a major threat to ground-nesting birds, our results suggest that an annual removal of vegetation may reduce predation risk in the subsequent year.

Efficient propagation-inside-layer expansion algorithm for solving the scattering from three-dimensional nested homogeneous dielectric bodies with arbitrary shape.

PubMed

Bellez, Sami; Bourlier, Christophe; Kubické, Gildas

2015-03-01

This paper deals with the evaluation of electromagnetic scattering from a three-dimensional structure consisting of two nested homogeneous dielectric bodies with arbitrary shape. The scattering problem is formulated in terms of a set of Poggio-Miller-Chang-Harrington-Wu integral equations that are afterwards converted into a system of linear equations (impedance matrix equation) by applying the Galerkin method of moments (MoM) with Rao-Wilton-Glisson basis functions. The MoM matrix equation is then solved by deploying the iterative propagation-inside-layer expansion (PILE) method in order to obtain the unknown surface current densities, which are thereafter used to handle the radar cross-section (RCS) patterns. Some numerical results for various structures including canonical geometries are presented and compared with those of the FEKO software in order to validate the PILE-based approach as well as to show its efficiency to analyze the full-polarized RCS patterns.

Nesting in an Object Oriented Language is NOT for the Birds

NASA Astrophysics Data System (ADS)

Buhr, P. A.; Zarnke, C. R.

The notion of nested blocks has come into disfavour or has been ignored in recent program language design. Many of the current object oriented programming languages use subclassing as the sole mechanism to establish relationships between classes and have no general notion of nesting. We argue that nesting (and, more generally, hierarchical organization) is a powerful mechanism that provides facilities that are not otherwise possible in a class based programming language. We agree that traditional block structure and its associated nesting have severe problems, and we suggest several extensions to the notion of blocks and block structure that indirectly make nesting a useful and powerful mechanism, particularly in an object oriented programming system. The main extension is to allow references to definitions from outside of the containing block, thereby making the contained definitions available in a larger scope. References are made using either the name of the containing entity or an instance of the containing entity. The extensions suggest a way to organize the programming environment for a large, multi-user system. These facilities are not available with subclassing, and subclassing provides facilities not available by nesting; hence, an object oriented language can benefit by providing nesting as well.

Nested association mapping of stem rust resistance in wheat using genotyping by sequencing

USDA-ARS?s Scientific Manuscript database

Nested association mapping is an approach to map trait loci in which families within populations are interconnected by a common parent. By implementing joint-linkage association analysis, this approach is able to map causative loci with higher power and resolution compared to biparental linkage mapp...

Observer visitation frequency and success of mourning dove nests: A field experiment

USGS Publications Warehouse

Nichols, J.D.; Percival, H.F.; Coon, R.A.; Conroy, M.J.; Hensler, G.L.; Hines, J.E.

1984-01-01

Field studies of nesting success generally require visits by the investigator to the nests under study. Such visits may themselves influence nesting success, however, and this possibility has been discussed and investigated by a number of workers with a variety of bird species. Livezey (1980) reviewed the relevant literature for duck nests and noted that most studies failed to demonstrate differences in nesting success between visited nests and those not visited. Livezey (1980) found in his own work that nest abandonment may have occurred as a result of disturbance by observers but that nest predation was not related to time spent by observers at nests or number of observers approaching nests. Various components of nesting and breeding success in seabirds are thought to be adversely affected by human disturbance and nest visitation (Gillett et al. 1975, Robert and Ralph 1975, Ollason and Dunnet 1980). Upland, ground-nesting species have also been studied (e.g. Stoddard 1931, Evans and Wolfe 1967, Henry 1969, Roseberry and Klimstra 1970, Klimstra and Roseberry 1975), and, although conclusions have varied, a number of these workers found no effect of observers on nest-predation rates.

Sound absorption of a new oblique-section acoustic metamaterial with nested resonator

NASA Astrophysics Data System (ADS)

Gao, Nansha; Hou, Hong; Zhang, Yanni; Wu, Jiu Hui

2018-02-01

This study designs and investigates high-efficiency sound absorption of new oblique-section nested resonators. Impedance tube experiment results show that different combinations of oblique-section nest resonators have tunable low-frequency bandwidth characteristics. The sound absorption mechanism is due to air friction losses in the slotted region and the sample structure resonance. The acousto-electric analogy model demonstrates that the sound absorption peak and bandwidth can be modulated over an even wider frequency range by changing the geometric size and combinations of structures. The proposed structure can be easily fabricated and used in low-frequency sound absorption applications.

Formation mechanism of photo-induced nested wrinkles on siloxane-photomonomer hybrid film

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

Suzuki, Kazumasa; International Laboratory of Materials Science and Nanotechnology; Laboratorio di Scienz

Nested wrinkle structures, hierarchical surface wrinkles of different periodicities of sub-μm and tens-μm, have been fabricated on a siloxane-photomonomer hybrid film via a photo-induced surface polymerization of acrylamide. The formation mechanism of the nested wrinkle structures is examined based on a time-dependent structure observation and chemical composition analyses. In-situ observation of the evolving surface structure showed that sub-μm scale wrinkles first formed, subsequently the tens-μm scale ones did. In-situ FT-IR analysis indicated that the nested wrinkles formation took place along with the development of siloxane network of under layer. A cross sectional observation of the film revealed that the filmmore » was composed of three layers. FT-IR spectra of the film revealed that the surface and interior layers were polyacrylamide rich layer and siloxane-polymer rich layer, respectively. The intermediate layer formed as a diffusion layer by migration of acrylamide from interior to the surface. These three layers have different chemical compositions and therefore different mechanical characteristics, which allows the wrinkle formation. Shrinkage of siloxane-polymer interior layers, as a result of polycondensation of siloxane network, induced mechanical instabilities at interlayers, to form the nested wrinkle structures.« less

Risky business: Site selection by Acadian Flycatchers under threat of nest predation and brood parasitism

USGS Publications Warehouse

HazIer, K.R.; Cooper, R.J.; Twedt, D.J.

2006-01-01

Habitat quality is determined not only by habitat structure and the availability of resources, but also by competitors, cooperators, predators, and parasites. We hypothesized that, for passerines, minimizing risk from avian nest predators and brood parasites is an important factor in selecting a breeding site. Through the early part of two breeding seasons, we spot-mapped locations of Acadian Flycatchers (Empidonax virescens, territory selectors), Red-bellied Woodpeckers (Melanerpes carolinus, nest predators) and Brown-headed Cowbirds (Molothrus ater, brood parasites) in a 56-ha study area within an extensive bottomland hardwood forest. We were thereby able to determine the order of flycatcher territory settlement and nest initiation in relation to risk of predation and parasitism, while accounting for habitat structure. Male settlement was influenced by both habitat structure and risk avoidance. However, risk trom woodpeckers was relatively more important in the first season and risk from cowbirds in the second, evidently due to differences in the relative abundance of predator and brood-parasite in each year. For male flycatchers, settlement choices appear to be flexible in the face of changing 'risk landscapes.' For females, habitat structure was the most important predictor of nest site selection. Even so, there was evidence that females avoided cowbirds. Surprisingly, nest site selection was positively associated with woodpecker abundance in the first season when woodpeckers were present in greater numbers. Possible explanations for this contradictory result are discussed.

Nesting habits shape feeding preferences and predatory behavior in an ant genus

NASA Astrophysics Data System (ADS)

Dejean, Alain; Labrière, Nicolas; Touchard, Axel; Petitclerc, Frédéric; Roux, Olivier

2014-04-01

We tested if nesting habits influence ant feeding preferences and predatory behavior in the monophyletic genus Pseudomyrmex (Pseudomyrmecinae) which comprises terrestrial and arboreal species, and, among the latter, plant-ants which are obligate inhabitants of myrmecophytes (i.e., plants sheltering so-called plant-ants in hollow structures). A cafeteria experiment revealed that the diet of ground-nesting Pseudomyrmex consists mostly of prey and that of arboreal species consists mostly of sugary substances, whereas the plant-ants discarded all the food we provided. Workers forage solitarily, detecting prey from a distance thanks to their hypertrophied eyes. Approach is followed by antennal contact, seizure, and the manipulation of the prey to sting it under its thorax (next to the ventral nerve cord). Arboreal species were not more efficient at capturing prey than were ground-nesting species. A large worker size favors prey capture. Workers from ground- and arboreal-nesting species show several uncommon behavioral traits, each known in different ant genera from different subfamilies: leaping abilities, the use of surface tension strengths to transport liquids, short-range recruitment followed by conflicts between nestmates, the consumption of the prey's hemolymph, and the retrieval of entire prey or pieces of prey after having cut it up. Yet, we never noted group ambushing. We also confirmed that Pseudomyrmex plant-ants live in a kind of food autarky as they feed only on rewards produced by their host myrmecophyte, or on honeydew produced by the hemipterans they attend and possibly on the fungi they cultivate.

Flexible social organization and high incidence of drifting in the sweat bee, Halictus scabiosae.

PubMed

Ulrich, Yuko; Perrin, Nicolas; Chapuisat, Michel

2009-04-01

The very diverse social systems of sweat bees make them interesting models to study social evolution. Here we focus on the dispersal behaviour and social organization of Halictus scabiosae, a common yet poorly known species of Europe. By combining field observations and genetic data, we show that females have multiple reproductive strategies, which generates a large diversity in the social structure of nests. A detailed microsatellite analysis of 60 nests revealed that 55% of the nests contained the offspring of a single female, whereas the rest had more complex social structures, with three clear cases of multiple females reproducing in the same nest and frequent occurrence of unrelated individuals. Drifting among nests was surprisingly common, as 16% of the 122 nests in the overall sample and 44% of the nests with complex social structure contained females that had genotypes consistent with being full-sisters of females sampled in other nests of the population. Drifters originated from nests with an above-average productivity and were unrelated to their nestmates, suggesting that drifting might be a strategy to avoid competition among related females. The sex-specific comparison of genetic differentiation indicated that dispersal was male-biased, which would reinforce local resource competition among females. The pattern of genetic differentiation among populations was consistent with a dynamic process of patch colonization and extinction, as expected from the unstable, anthropogenic habitat of this species. Overall, our data show that H. scabiosae varies greatly in dispersal behaviour and social organization. The surprisingly high frequency of drifters echoes recent findings in wasps and bees, calling for further investigation of the adaptive basis of drifting in the social insects.

Nested mesoscale-to-LES modeling of the atmospheric boundary layer in the presence of under-resolved convective structures

DOE PAGES

Mazzaro, Laura J.; Munoz-Esparza, Domingo; Lundquist, Julie K.; ...

2017-07-06

Multiscale atmospheric simulations can be computationally prohibitive, as they require large domains and fine spatiotemporal resolutions. Grid-nesting can alleviate this by bridging mesoscales and microscales, but one turbulence scheme must run at resolutions within a range of scales known as the terra incognita (TI). TI grid-cell sizes can violate both mesoscale and microscale subgrid-scale parametrization assumptions, resulting in unrealistic flow structures. Herein we assess the impact of unrealistic lateral boundary conditions from parent mesoscale simulations at TI resolutions on nested large eddy simulations (LES), to determine whether parent domains bias the nested LES. We present a series of idealized nestedmore » mesoscale-to-LES runs of a dry convective boundary layer (CBL) with different parent resolutions in the TI. We compare the nested LES with a stand-alone LES with periodic boundary conditions. The nested LES domains develop ~20% smaller convective structures, while potential temperature profiles are nearly identical for both the mesoscales and LES simulations. The horizontal wind speed and surface wind shear in the nested simulations closely resemble the reference LES. Heat fluxes are overestimated by up to ~0.01 K m s –1 in the top half of the PBL for all nested simulations. Overestimates of turbulent kinetic energy (TKE) and Reynolds stress in the nested domains are proportional to the parent domain's grid-cell size, and are almost eliminated for the simulation with the finest parent grid-cell size. Furthermore, based on these results, we recommend that LES of the CBL be forced by mesoscale simulations with the finest practical resolution.« less

Nested mesoscale-to-LES modeling of the atmospheric boundary layer in the presence of under-resolved convective structures

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

Mazzaro, Laura J.; Munoz-Esparza, Domingo; Lundquist, Julie K.

Multiscale atmospheric simulations can be computationally prohibitive, as they require large domains and fine spatiotemporal resolutions. Grid-nesting can alleviate this by bridging mesoscales and microscales, but one turbulence scheme must run at resolutions within a range of scales known as the terra incognita (TI). TI grid-cell sizes can violate both mesoscale and microscale subgrid-scale parametrization assumptions, resulting in unrealistic flow structures. Herein we assess the impact of unrealistic lateral boundary conditions from parent mesoscale simulations at TI resolutions on nested large eddy simulations (LES), to determine whether parent domains bias the nested LES. We present a series of idealized nestedmore » mesoscale-to-LES runs of a dry convective boundary layer (CBL) with different parent resolutions in the TI. We compare the nested LES with a stand-alone LES with periodic boundary conditions. The nested LES domains develop ~20% smaller convective structures, while potential temperature profiles are nearly identical for both the mesoscales and LES simulations. The horizontal wind speed and surface wind shear in the nested simulations closely resemble the reference LES. Heat fluxes are overestimated by up to ~0.01 K m s –1 in the top half of the PBL for all nested simulations. Overestimates of turbulent kinetic energy (TKE) and Reynolds stress in the nested domains are proportional to the parent domain's grid-cell size, and are almost eliminated for the simulation with the finest parent grid-cell size. Furthermore, based on these results, we recommend that LES of the CBL be forced by mesoscale simulations with the finest practical resolution.« less

From neurons to nests: nest-building behaviour as a model in behavioural and comparative neuroscience.

PubMed

Hall, Zachary J; Meddle, Simone L; Healy, Susan D

Despite centuries of observing the nest building of most extant bird species, we know surprisingly little about how birds build nests and, specifically, how the avian brain controls nest building. Here, we argue that nest building in birds may be a useful model behaviour in which to study how the brain controls behaviour. Specifically, we argue that nest building as a behavioural model provides a unique opportunity to study not only the mechanisms through which the brain controls behaviour within individuals of a single species but also how evolution may have shaped the brain to produce interspecific variation in nest-building behaviour. In this review, we outline the questions in both behavioural and comparative neuroscience that nest building could be used to address, summarize recent findings regarding the neurobiology of nest building in lab-reared zebra finches and across species building different nest structures, and suggest some future directions for the neurobiology of nest building.

Estimating raptor nesting success: old and new approaches

USGS Publications Warehouse

Brown, Jessi L.; Steenhof, Karen; Kochert, Michael N.; Bond, Laura

2013-01-01

Studies of nesting success can be valuable in assessing the status of raptor populations, but differing monitoring protocols can present unique challenges when comparing populations of different species across time or geographic areas. We used large datasets from long-term studies of 3 raptor species to compare estimates of apparent nest success (ANS, the ratio of successful to total number of nesting attempts), Mayfield nesting success, and the logistic-exposure model of nest survival. Golden eagles (Aquila chrysaetos), prairie falcons (Falco mexicanus), and American kestrels (F. sparverius) differ in their breeding biology and the methods often used to monitor their reproduction. Mayfield and logistic-exposure models generated similar estimates of nesting success with similar levels of precision. Apparent nest success overestimated nesting success and was particularly sensitive to inclusion of nesting attempts discovered late in the nesting season. Thus, the ANS estimator is inappropriate when exact point estimates are required, especially when most raptor pairs cannot be located before or soon after laying eggs. However, ANS may be sufficient to assess long-term trends of species in which nesting attempts are highly detectable.

A Nested or Composite Shatter Cone Structure in the South Range of Sudbury

NASA Astrophysics Data System (ADS)

Hurwitz, D. M.; Zanetti, M.; Lucas, M. P.; Anders, D.; Kramer, G.; Thomson, O.; Kring, D. A.; Osinski, G. R.

2013-08-01

In a recent survey of Sudbury shatter cones, we identified an outcrop of stacked, curvilinear foliations with well-developed, nested shatter cones that trend toward the apex of the foliations. We interpret this structure as a composite cone.

Nest guarding by female Agassiz's desert tortoise (Gopherus agassizii) at a wind-energy facility near Palm Springs, California

USGS Publications Warehouse

Agha, Mickey; Lovich, Jeffrey E.; Ennen, Joshua R.; Wilcox, Ethan

2013-01-01

We observed behavior consistent with nest-guarding in Agassiz's desert tortoise (Gopherus agassizii) at two nests in a large wind-energy-generation facility near Palm Springs, California, locally known as the Mesa Wind Farm. As researchers approached the nests, female desert tortoises moved to the entrance of their burrows and positioned themselves sideways, directly over their nests. One female stretched her limbs outward and wedged herself into the burrow (her plastron directly above the nest). Guarding of nests is rarely observed in Agassiz's desert tortoise but can occur as a result of attempted predation on eggs by Gila monsters (Heloderma suspectum) or in direct response to the perceived threat posed by researchers. This is the first report of nest-guarding for G. agassizii in the Sonoran Desert ecosystem of California.

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

Khalid, Farah F.; Deptuch, Grzegorz; Shenai, Alpana

Monolithic Active Matrix with Binary Counters (MAMBO) is a counting ASIC designed for detecting and measuring low energy X-rays from 6-12 keV. Each pixel contains analogue functionality implemented with a charge preamplifier, CR-RC{sup 2} shaper and a baseline restorer. It also contains a window comparator which can be trimmed by 4 bit DACs to remove systematic offsets. The hits are registered by a 12 bit ripple counter which is reconfigured as a shift register to serially output the data from the entire ASIC. Each pixel can be tested individually. Two diverse approaches have been used to prevent coupling between themore » detector and electronics in MAMBO III and MAMBO IV. MAMBO III is a 3D ASIC, the bottom ASIC consists of diodes which are connected to the top ASIC using {mu}-bump bonds. The detector is decoupled from the electronics by physically separating them on two tiers and using several metal layers as a shield. MAMBO IV is a monolithic structure which uses a nested well approach to isolate the detector from the electronics. The ASICs are being fabricated using the SOI 0.2 {micro}m OKI process, MAMBO III is 3D bonded at T-Micro and MAMBO IV nested well structure was developed in collaboration between OKI and Fermilab.« less

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

Khalid, Farah; Deptuch, Grzegorz; Shenai, Alpana

Monolithic Active Matrix with Binary Counters (MAMBO) is a counting ASIC designed for detecting and measuring low energy X-rays from 6-12keV. Each pixel contains analogue functionality implemented with a charge preamplifier, CR-RC{sup 2} shaper and a baseline restorer. It also contains a window comparator which can be trimmed by 4 bit DACs to remove systematic offsets. The hits are registered by a 12 bit ripple counter which is reconfigured as a shift register to serially output the data from the entire ASIC. Each pixel can be tested individually. Two diverse approaches have been used to prevent coupling between the detectormore » and electronics in MAMBO III and MAMBO IV. MAMBO III is a 3D ASIC, the bottom ASIC consists of diodes which are connected to the top ASIC using {mu}-bump bonds. The detector is decoupled from the electronics by physically separating them on two tiers and using several metal layers as a shield. MAMBO IV is a monolithic structure which uses a nested well approach to isolate the detector from the electronics. The ASICs are being fabricated using the SOI 0.2 {micro}m OKI process, MAMBO III is 3D bonded at T-Micro and MAMBO IV nested well structure was developed in collaboration between OKI and Fermilab.« less

Seasonal and spatial community dynamics in the meromictic Lake Cadagno.

PubMed

Bosshard, P P; Stettler, R; Bachofen, R

2000-09-01

The seasonal and spatial variations in the community structure of bacterioplankton in the meromictic alpine Lake Cadagno were examined by temporal temperature gradient gel electrophoresis (TTGE) of PCR-amplified 16S rDNA fragments. Two different amplifications were performed, one specific for the domain Bacteria (Escherichia coli positions 8-536) and another specific for the family Chromatiaceae (E. coli positions 8-1005). The latter was followed by semi-nested reamplification with the bacterial primer set, allowing comparison of the two PCR approaches by TTGE. The TTGE patterns of samples from the chemocline and the anoxic monimolimnion were essentially identical, whereas the oxic mixolimnion displayed distinctively different banding patterns. For samples from the chemocline and the monimolimnion, dominant bands in the Bacteria-specific TTGE profiles comigrated with bands obtained by the semi-nested PCR approach specific for Chromatiaceae. This observation suggested that Chromatiaceae are in high abundance in the anoxic water layer. All dominant bands were excised and sequenced. Changes in the community structure, as indicated by changes in the TTGE profiles, were observed in samples taken at different times of the year. In the chemocline, Chomatium okenii was dominant in the summer months, whereas Amoebobacter purpureus populations dominated in autumn and winter. This change was confirmed by fluorescent in situ hybridization.

Variation in spatial scale of competing polydomous twig-nesting ants in coffee agroecosystems

PubMed Central

Mathis, Kaitlyn A.; Philpott, Stacy M.; Ramirez, Santiago R.

2016-01-01

Arboreal ants are both highly diverse and ecologically dominant in the tropics. This ecologically important group is particularly useful in ongoing efforts to understand processes that regulate species diversity and coexistence. Our study addresses how polydomy can influence patterns of nest occupation in competing arboreal ants. We examined the spatial structure of nest occupation (nest distance, abundance and density) in three polydomous co-occurring twig-nesting ant species (Pseudomyrmex simplex, P. ejectus and P. PSW-53) by mapping twigs occupied by ants from each species within plots in our study site. We then used two colony structure estimators (intraspecific aggression and cuticular hydrocarbon variation) to determine the relative degree of polydomy for each species. All work was conducted in coffee agroforests in Chiapas, Mexico. Our results revealed that the two species with highest abundance and nest density were also highly polydomous, where both species had either single or multiple non-aggressive colonies occupying nests on a large spatial scale (greater than the hectare level). Our results also indicate that the species with the lowest abundance and density is less polydomous, occupying several overlapping and territorial colonies at the hectare level in which multiple colonies never co-occur on the same host plant. These results contribute evidence that successful coexistence and highly polydomous colony structure may allow ants, through reduced intraspecific aggression, to successfully occupy more nests more densely than ant species that have multiple territorial colonies. Furthermore our study highlights the importance of considering intraspecific interactions when examining community assembly of ants. PMID:27795573

Industrious leaf cutter ants and their carbon footprints

NASA Astrophysics Data System (ADS)

Swanson, A. C.; Dierick, D.; Trahan, N. A.; Allen, M. F.; Schwendenmann, L.; Harmon, T. C.; Oberbauer, S. F.; Fernandez Bou, A. S.; Zelikova, T. J.

2017-12-01

Leaf cutter ants (LCA) are considered ecosystem engineers in Neotropical forest ecosystems because they alter physical and environmental conditions for other organisms. LCA excavate large underground nests, maintaining intricate tunnels and fungal and waste chambers, and they continuously bring in vast amounts of fresh leaf material. In order to understand their ecosystem-wide impacts, we set out to determine whether their engineering activities fundamentally alter soil structure, soil nutrient pools, and gas fluxes in a wet tropical rainforest in Costa Rica. To directly compare LCA nest to non-nest sites, we utilized embedded sensor arrays with series of soil moisture, CO2, O2, and temperature sensors placed at four soil depths and automated minirhizotrons (AMR) to measure root and hyphal production and turnover. We also collected soils for biogeochemical analyses and measured soil CO2 fluxes and carbon isotope ratios of below-ground CO2 for two years. Our measurements confirmed that LCA alter their soil environment to regulate internal soil CO2 concentrations, moisture, and temperature, increasing O2 concentrations in the process. There were marked differences in soil structure inside nests relative to non-nests and these were associated with increased root and hyphal production and turnover in nests. Soil C, N, P, and their respective degrading enzymes were highly variable among sites and between nests and controls but N and P increased with soil depth and were generally higher in nests than controls. Contrary to our expectations, C mineralization rates were lower in nests but CO2 fluxes were high from nest vents and similar to non-nests elsewhere. At the system scale, LCA appear to fundamentally change the soil environment inside their nests and create spatial heterogeneity in biogeochemical processes and root and hyphal growth, influencing the overall C balance of Neotropical forests.

Nested-scale discharge and groundwater level monitoring to improve predictions of flow route discharges and nitrate loads

NASA Astrophysics Data System (ADS)

van der Velde, Y.; Rozemeijer, J. C.; de Rooij, G. H.; van Geer, F. C.; Torfs, P. J. J. F.; de Louw, P. G. B.

2010-10-01

Identifying effective measures to reduce nutrient loads of headwaters in lowland catchments requires a thorough understanding of flow routes of water and nutrients. In this paper we assess the value of nested-scale discharge and groundwater level measurements for predictions of catchment-scale discharge and nitrate loads. In order to relate field-site measurements to the catchment-scale an upscaling approach is introduced that assumes that scale differences in flow route fluxes originate from differences in the relationship between groundwater storage and the spatial structure of the groundwater table. This relationship is characterized by the Groundwater Depth Distribution (GDD) curve that relates spatial variation in groundwater depths to the average groundwater depth. The GDD-curve was measured for a single field site (0.009 km2) and simple process descriptions were applied to relate the groundwater levels to flow route discharges. This parsimonious model could accurately describe observed storage, tube drain discharge, overland flow and groundwater flow simultaneously with Nash-Sutcliff coefficients exceeding 0.8. A probabilistic Monte Carlo approach was applied to upscale field-site measurements to catchment scales by inferring scale-specific GDD-curves from hydrographs of two nested catchments (0.4 and 6.5 km2). The estimated contribution of tube drain effluent (a dominant source for nitrates) decreased with increasing scale from 76-79% at the field-site to 34-61% and 25-50% for both catchment scales. These results were validated by demonstrating that a model conditioned on nested-scale measurements simulates better nitrate loads and better predictions of extreme discharges during validation periods compared to a model that was conditioned on catchment discharge only.

Improving catchment discharge predictions by inferring flow route contributions from a nested-scale monitoring and model setup

NASA Astrophysics Data System (ADS)

van der Velde, Y.; Rozemeijer, J. C.; de Rooij, G. H.; van Geer, F. C.; Torfs, P. J. J. F.; de Louw, P. G. B.

2011-03-01

Identifying effective measures to reduce nutrient loads of headwaters in lowland catchments requires a thorough understanding of flow routes of water and nutrients. In this paper we assess the value of nested-scale discharge and groundwater level measurements for the estimation of flow route volumes and for predictions of catchment discharge. In order to relate field-site measurements to the catchment-scale an upscaling approach is introduced that assumes that scale differences in flow route fluxes originate from differences in the relationship between groundwater storage and the spatial structure of the groundwater table. This relationship is characterized by the Groundwater Depth Distribution (GDD) curve that relates spatial variation in groundwater depths to the average groundwater depth. The GDD-curve was measured for a single field site (0.009 km2) and simple process descriptions were applied to relate groundwater levels to flow route discharges. This parsimonious model could accurately describe observed storage, tube drain discharge, overland flow and groundwater flow simultaneously with Nash-Sutcliff coefficients exceeding 0.8. A probabilistic Monte Carlo approach was applied to upscale field-site measurements to catchment scales by inferring scale-specific GDD-curves from the hydrographs of two nested catchments (0.4 and 6.5 km2). The estimated contribution of tube drain effluent (a dominant source for nitrates) decreased with increasing scale from 76-79% at the field-site to 34-61% and 25-50% for both catchment scales. These results were validated by demonstrating that a model conditioned on nested-scale measurements improves simulations of nitrate loads and predictions of extreme discharges during validation periods compared to a model that was conditioned on catchment discharge only.

An object-oriented approach to nested data parallelism

NASA Technical Reports Server (NTRS)

Sheffler, Thomas J.; Chatterjee, Siddhartha

1994-01-01

This paper describes an implementation technique for integrating nested data parallelism into an object-oriented language. Data-parallel programming employs sets of data called 'collections' and expresses parallelism as operations performed over the elements of a collection. When the elements of a collection are also collections, then there is the possibility for 'nested data parallelism.' Few current programming languages support nested data parallelism however. In an object-oriented framework, a collection is a single object. Its type defines the parallel operations that may be applied to it. Our goal is to design and build an object-oriented data-parallel programming environment supporting nested data parallelism. Our initial approach is built upon three fundamental additions to C++. We add new parallel base types by implementing them as classes, and add a new parallel collection type called a 'vector' that is implemented as a template. Only one new language feature is introduced: the 'foreach' construct, which is the basis for exploiting elementwise parallelism over collections. The strength of the method lies in the compilation strategy, which translates nested data-parallel C++ into ordinary C++. Extracting the potential parallelism in nested 'foreach' constructs is called 'flattening' nested parallelism. We show how to flatten 'foreach' constructs using a simple program transformation. Our prototype system produces vector code which has been successfully run on workstations, a CM-2, and a CM-5.

An optimized one-tube, semi-nested PCR assay for Paracoccidioides brasiliensis detection.

PubMed

Pitz, Amanda de Faveri; Koishi, Andrea Cristine; Tavares, Eliandro Reis; Andrade, Fábio Goulart de; Loth, Eduardo Alexandre; Gandra, Rinaldo Ferreira; Venancio, Emerson José

2013-01-01

Herein, we report a one-tube, semi-nested-polymerase chain reaction (OTsn-PCR) assay for the detection of Paracoccidioides brasiliensis. We developed the OTsn-PCR assay for the detection of P. brasiliensis in clinical specimens and compared it with other PCR methods. The OTsn-PCR assay was positive for all clinical samples, and the detection limit was better or equivalent to the other nested or semi-nested PCR methods for P. brasiliensis detection. The OTsn-PCR assay described in this paper has a detection limit similar to other reactions for the molecular detection of P. brasiliensis, but this approach is faster and less prone to contamination than other conventional nested or semi-nested PCR assays.

High-tech or field techs: Radio-telemetry is a cost-effective method for reducing bias in songbird nest searching

USGS Publications Warehouse

Peterson, Sean M.; Streby, Henry M.; Lehman, Justin A.; Kramer, Gunnar R.; Fish, Alexander C.; Andersen, David E.

2015-01-01

We compared the efficacy of standard nest-searching methods with finding nests via radio-tagged birds to assess how search technique influenced our determination of nest-site characteristics and nest success for Golden-winged Warblers (Vermivora chrysoptera). We also evaluated the cost-effectiveness of using radio-tagged birds to find nests. Using standard nest-searching techniques for 3 populations, we found 111 nests in locations with habitat characteristics similar to those described in previous studies: edges between forest and relatively open areas of early successional vegetation or shrubby wetlands, with 43% within 5 m of forest edge. The 83 nests found using telemetry were about half as likely (23%) to be within 5 m of forest edge. We spent little time searching >25 m into forest because published reports state that Golden-winged Warblers do not nest there. However, 14 nests found using telemetry (18%) were >25 m into forest. We modeled nest success using nest-searching method, nest age, and distance to forest edge as explanatory variables. Nest-searching method explained nest success better than nest age alone; we estimated that nests found using telemetry were 10% more likely to fledge young than nests found using standard nest-searching methods. Although radio-telemetry was more expensive than standard nest searching, the cost-effectiveness of both methods differed depending on searcher experience, amount of equipment owned, and bird population density. Our results demonstrate that telemetry can be an effective method for reducing bias in Golden-winged Warbler nest samples, can be cost competitive with standard nest-searching methods in some situations, and is likely to be a useful approach for finding nests of other forest-nesting songbirds.

Aircraft applications of fault detection and isolation techniques

NASA Astrophysics Data System (ADS)

Marcos Esteban, Andres

In this thesis the problems of fault detection & isolation and fault tolerant systems are studied from the perspective of LTI frequency-domain, model-based techniques. Emphasis is placed on the applicability of these LTI techniques to nonlinear models, especially to aerospace systems. Two applications of Hinfinity LTI fault diagnosis are given using an open-loop (no controller) design approach: one for the longitudinal motion of a Boeing 747-100/200 aircraft, the other for a turbofan jet engine. An algorithm formalizing a robust identification approach based on model validation ideas is also given and applied to the previous jet engine. A general linear fractional transformation formulation is given in terms of the Youla and Dual Youla parameterizations for the integrated (control and diagnosis filter) approach. This formulation provides better insight into the trade-off between the control and the diagnosis objectives. It also provides the basic groundwork towards the development of nested schemes for the integrated approach. These nested structures allow iterative improvements on the control/filter Youla parameters based on successive identification of the system uncertainty (as given by the Dual Youla parameter). The thesis concludes with an application of Hinfinity LTI techniques to the integrated design for the longitudinal motion of the previous Boeing 747-100/200 model.

A smoothed residual based goodness-of-fit statistic for nest-survival models

Treesearch

Rodney X. Sturdivant; Jay J. Rotella; Robin E. Russell

2008-01-01

Estimating nest success and identifying important factors related to nest-survival rates is an essential goal for many wildlife researchers interested in understanding avian population dynamics. Advances in statistical methods have led to a number of estimation methods and approaches to modeling this problem. Recently developed models allow researchers to include a...

Improvement of DGGE analysis by modifications of PCR protocols for analysis of microbial community members with low abundance.

PubMed

Wang, Yong-Feng; Zhang, Fang-Qiu; Gu, Ji-Dong

2014-06-01

Denaturing gradient gel electrophoresis (DGGE) is a powerful technique to reveal the community structures and composition of microorganisms in complex natural environments and samples. However, positive and reproducible polymerase chain reaction (PCR) products, which are difficult to acquire for some specific samples due to low abundance of the target microorganisms, significantly impair the effective applications of DGGE. Thus, nested PCR is often introduced to generate positive PCR products from the complex samples, but one problem is also introduced: The total number of thermocycling in nested PCR is usually unacceptably high, which results in skewed community structures by generation of random or mismatched PCR products on the DGGE gel, and this was demonstrated in this study. Furthermore, nested PCR could not resolve the uneven representative issue with PCR products of complex samples with unequal richness of microbial population. In order to solve the two problems in nested PCR, the general protocol was modified and improved in this study. Firstly, a general PCR procedure was used to amplify the target genes with the PCR primers without any guanine cytosine (GC) clamp, and then, the resultant PCR products were purified and diluted to 0.01 μg ml(-1). Subsequently, the diluted PCR products were utilized as templates to amplify again with the same PCR primers with the GC clamp for 17 cycles, and the products were finally subjected to DGGE analysis. We demonstrated that this is a much more reliable approach to obtain a high quality DGGE profile with high reproducibility. Thus, we recommend the adoption of this improved protocol in analyzing microorganisms of low abundance in complex samples when applying the DGGE fingerprinting technique to avoid biased results.

Shrub Nesting of the Red-Eyed Vireo in Relation to Structure of Aspen Forests

Treesearch

William J. Jr Mattson

1979-01-01

Nests were built in five species of high shrubs in four trembling aspen forests of northern Minnesoa. Nest densities ranged between 0.5 and 3.0 per acre and were positively related to the abundance3 of large (>1.2-cm diameter) shrub stems.

The Implications of Contamination for Educational Experiments with Two Levels of Nesting

ERIC Educational Resources Information Center

Rhoads, Christopher

2016-01-01

Experimental evaluations that involve the educational system usually involve a hierarchical structure (students are nested within classrooms that are nested within schools, etc.). Concerns about contamination, where research subjects receive certain features of an intervention intended for subjects in a different experimental group, have often led…

Breeding behavior of immature mourning doves

USGS Publications Warehouse

Irby, H.D.; Blankenship, L.H.

1966-01-01

Some immature mourning doves (Zenaidura mncroura) are capable of breeding in their first (calendar) year of life. The breeding activities of immatures observed in this study included calling, copulating, and nesting. Development of sexual structures such as cloacal papillae, oviduct openings, and gonads was also regarded as evidence of breeding potential. Immatures were identified principally by white-tipped wing coverts. Sexes were distinguished by behavioral characteristics. Males coo, perform flights, carry nest material, and attend nests during the day and females attend nests at night. Immatures were involved in at least ten nestings on two areas near Tucson, Arizona, in 1963. Five young fledged from these nests.

Fire and shade effects on ground cover structure in Kirtland's warbler habitat

Treesearch

John R. Probst; Deahn DonnerWright

2003-01-01

Researchers and managers have suggested that a narrow range of ground-cover structure resulting from fire might be necessary for suitable Kirtland`s warbler nesting conditions. Yet, Kirtland`s warblers have bred successfully in numerous unburned stands and there is little direct evidence to indicate that ground cover structure is a limiting factor for nest sites or...

An Odds Ratio Approach for Detecting DDF under the Nested Logit Modeling Framework

ERIC Educational Resources Information Center

Terzi, Ragip; Suh, Youngsuk

2015-01-01

An odds ratio approach (ORA) under the framework of a nested logit model was proposed for evaluating differential distractor functioning (DDF) in multiple-choice items and was compared with an existing ORA developed under the nominal response model. The performances of the two ORAs for detecting DDF were investigated through an extensive…

Monitoring bald eagles using lists of nests: Response to Watts and Duerr

USGS Publications Warehouse

Sauer, John R.; Otto, Mark C.; Kendall, William L.; Zimmerman, Guthrie S.

2011-01-01

The post-delisting monitoring plan for bald eagles (Haliaeetus leucocephalus) roposed use of a dual-frame sample design, in which sampling of known nest sites in combination with additional area-based sampling is used to estimate total number of nesting bald eagle pairs. Watts and Duerr (2010) used data from repeated observations of bald eagle nests in Virginia, USA to estimate a nest turnover rate and used this rate to simulate decline in number of occupied nests in list nests over time. Results of Watts and Duerr suggest that, given the rates of loss of nests from the list of known nest sites in Virginia, the list information will be of little value to sampling unless lists are constantly updated. Those authors criticize the plan for not placing sufficient emphasis on updating and maintaining lists of bald eagle nests. Watts and Duerr's metric of turnover rate does not distinguish detectability or temporary nonuse of nests from permanent loss of nests and likely overestimates turnover rate. We describe a multi-state capture–recapture model that allows appropriate estimation of rates of loss of nests, and we use the model to estimate rates of loss from a sample of nests from Maine, USA. The post-delisting monitoring plan addresses the need to maintain and update the lists of nests, and we show that dual frame sampling is an effective approach for sampling nesting bald eagle populations.

Construction of nested maximin designs based on successive local enumeration and modified novel global harmony search algorithm

NASA Astrophysics Data System (ADS)

Yi, Jin; Li, Xinyu; Xiao, Mi; Xu, Junnan; Zhang, Lin

2017-01-01

Engineering design often involves different types of simulation, which results in expensive computational costs. Variable fidelity approximation-based design optimization approaches can realize effective simulation and efficiency optimization of the design space using approximation models with different levels of fidelity and have been widely used in different fields. As the foundations of variable fidelity approximation models, the selection of sample points of variable-fidelity approximation, called nested designs, is essential. In this article a novel nested maximin Latin hypercube design is constructed based on successive local enumeration and a modified novel global harmony search algorithm. In the proposed nested designs, successive local enumeration is employed to select sample points for a low-fidelity model, whereas the modified novel global harmony search algorithm is employed to select sample points for a high-fidelity model. A comparative study with multiple criteria and an engineering application are employed to verify the efficiency of the proposed nested designs approach.

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.

Nest site characteristics and nesting success of the Western Burrowing Owl in the eastern Mojave Desert

USGS Publications Warehouse

Longshore, Kathleen M.; Crowe, Dorothy E.

2013-01-01

We evaluated nest site selection at two spatial scales (microsite, territory) and reproductive success of Western Burrowing Owls (Athene cunicularia hypugaea) at three spatial scales (microsite, territory, landscape) in the eastern Mojave Desert. We used binary logistic regression within an information-theoretic approach to assess factors influencing nest site choice and nesting success. Microsite-scale variables favored by owls included burrows excavated by desert tortoise (Gopherus agassizii), burrows with a large mound of excavated soil at the entrance, and a greater number of satellite burrows within 5 m of the nest burrow. At the territory scale, owls preferred patches with greater cover of creosote bush (Larrea tridentata) within 50 m of the nest burrow. An interaction between the presence or absence of a calcic soil horizon layer over the top of the burrow (microsite) and the number of burrows within 50 m (territory) influenced nest site choice. Nesting success was influenced by a greater number of burrows within 5 m of the nest burrow. Total cool season precipitation was a predictor of nesting success at the landscape scale. Conservation strategies can rely on management of habitat for favored and productive nesting sites for this declining species.

Quantifying the social structure of a large captive flock of greater flamingos (Phoenicopterus roseus): Potential implications for management in captivity.

PubMed

Rose, Paul E; Croft, Darren P

2018-05-01

An appropriate social environment for species held in captivity is key for ensuring both good welfare and reproductive performance. Species with a complex social structure may suffer if their social requirements are not taken into consideration as part of management and husbandry strategies. Here we aim to understand the drivers of social structure, and the link between social structure and reproduction in a flock of 281 greater flamingos (Phoenicopterus roseus) at WWT Slimbridge Wetland Centre. Proximity-based associations between birds were measured three and four times per day (depending upon season and husbandry) from 2012 to 2016. To determine the effect of reproductive activity on social structure, display and nesting behaviour were also recorded for the 2015 breeding season (April-July). Results showed that birds displayed a wider range of social relationships, and that affiliations within the flock were not random. This flamingo flock was differentiated into discrete subgroups, and social structure was stable across some years, but not over all seasons. Social bonds were more consistent across seasons into the nesting period rather than outside of it. During breeding, not all birds that displayed built a nest, and not all displaying birds nested. Future research should further investigate differences in display and nesting patterns within a flock, and determine how the social structure of large flocks compares to smaller flocks of this species. Comparing captive data to information on wild bird sociality would be relevant to highlight any differences in patterns of assortment and connectivity. Copyright © 2018 Elsevier B.V. All rights reserved.

Nested Structural Equation Models: Noncentrality and Power of Restriction Test.

ERIC Educational Resources Information Center

Raykov, Tenko; Penev, Spiridon

1998-01-01

Discusses the difference in noncentrality parameters of nested structural equation models and their utility in evaluating statistical power associated with the pertinent restriction test. Asymptotic confidence intervals for that difference are presented. These intervals represent a useful adjunct to goodness-of-fit indexes in assessing constraints…

Linking occurrence and fitness to persistence: Habitat-based approach for endangered Greater Sage-Grouse

USGS Publications Warehouse

Aldridge, Cameron L.; Boyce, Mark S.

2007-01-01

Detailed empirical models predicting both species occurrence and fitness across a landscape are necessary to understand processes related to population persistence. Failure to consider both occurrence and fitness may result in incorrect assessments of habitat importance leading to inappropriate management strategies. We took a two-stage approach to identifying critical nesting and brood-rearing habitat for the endangered Greater Sage-Grouse (Centrocercus urophasianus) in Alberta at a landscape scale. First, we used logistic regression to develop spatial models predicting the relative probability of use (occurrence) for Sage-Grouse nests and broods. Secondly, we used Cox proportional hazards survival models to identify the most risky habitats across the landscape. We combined these two approaches to identify Sage-Grouse habitats that pose minimal risk of failure (source habitats) and attractive sink habitats that pose increased risk (ecological traps). Our models showed that Sage-Grouse select for heterogeneous patches of moderate sagebrush cover (quadratic relationship) and avoid anthropogenic edge habitat for nesting. Nests were more successful in heterogeneous habitats, but nest success was independent of anthropogenic features. Similarly, broods selected heterogeneous high-productivity habitats with sagebrush while avoiding human developments, cultivated cropland, and high densities of oil wells. Chick mortalities tended to occur in proximity to oil and gas developments and along riparian habitats. For nests and broods, respectively, approximately 10% and 5% of the study area was considered source habitat, whereas 19% and 15% of habitat was attractive sink habitat. Limited source habitats appear to be the main reason for poor nest success (39%) and low chick survival (12%). Our habitat models identify areas of protection priority and areas that require immediate management attention to enhance recruitment to secure the viability of this population. This novel approach to habitat-based population viability modeling has merit for many species of concern. ?? 2007 by the Ecological Society of America.

The use of root plates for nesting sites by Anthophora abrupta (Hymenoptera: Apidae) may be common within forested habitats

Treesearch

Joshua W. Campbell; Cynthia C. Viguiera; Patrick Viguiera; John E. Hartgerink; Cathryn H. Greenberg

2017-01-01

This is the first reported use of root plates by Anthophora abrupta Say (Hymenoptera: Apidae). Previous reported nesting sites were vertical riverbanks and several man-made clay structures. Root plates in forested habitats may be the preferred nesting site for A. abrupta.

Nested Neural Networks

NASA Technical Reports Server (NTRS)

Baram, Yoram

1992-01-01

Report presents analysis of nested neural networks, consisting of interconnected subnetworks. Analysis based on simplified mathematical models more appropriate for artificial electronic neural networks, partly applicable to biological neural networks. Nested structure allows for retrieval of individual subpatterns. Requires fewer wires and connection devices than fully connected networks, and allows for local reconstruction of damaged subnetworks without rewiring entire network.

Collaboration and nested environmental governance: Scale dependency, scale framing, and cross-scale interactions in collaborative conservation.

PubMed

Wyborn, Carina; Bixler, R Patrick

2013-07-15

The problem of fit between social institutions and ecological systems is an enduring challenge in natural resource management and conservation. Developments in the science of conservation biology encourage the management of landscapes at increasingly larger scales. In contrast, sociological approaches to conservation emphasize the importance of ownership, collaboration and stewardship at scales relevant to the individual or local community. Despite the proliferation of initiatives seeking to work with local communities to undertake conservation across large landscapes, there is an inherent tension between these scales of operation. Consequently, questions about the changing nature of effective conservation across scales abound. Through an analysis of three nested cases working in a semiautonomous fashion in the Northern Rocky Mountains in North America, this paper makes an empirical contribution to the literature on nested governance, collaboration and communication across scales. Despite different scales of operation, constituencies and scale frames, we demonstrate a surprising similarity in organizational structure and an implicit dependency between these initiatives. This paper examines the different capacities and capabilities of collaborative conservation from the local to regional to supra regional. We draw on the underexplored concept of 'scale-dependent comparative advantage' (Cash and Moser, 2000), to gain insight into what activities take place at which scale and what those activities contribute to nested governance and collaborative conservation. The comparison of these semiautonomous cases provides fruitful territory to draw lessons for understanding the roles and relationships of organizations operating at different scales in more connected networks of nested governance. Copyright © 2013 Elsevier Ltd. All rights reserved.

The construction of ventilation turrets in Atta vollenweideri leaf-cutting ants: Carbon dioxide levels in the nest tunnels, but not airflow or air humidity, influence turret structure

PubMed Central

Roces, Flavio

2017-01-01

Nest ventilation in the leaf-cutting ant Atta vollenweideri is driven via a wind-induced mechanism. On their nests, workers construct small turrets that are expected to facilitate nest ventilation. We hypothesized that the construction and structural features of the turrets would depend on the colony’s current demands for ventilation and thus might be influenced by the prevailing environmental conditions inside the nest. Therefore, we tested whether climate-related parameters, namely airflow, air humidity and CO2 levels in the outflowing nest air influenced turret construction in Atta vollenweideri. In the laboratory, we simulated a semi-natural nest arrangement with fungus chambers, a central ventilation tunnel providing outflow of air and an aboveground building arena for turret construction. In independent series, different climatic conditions inside the ventilation tunnel were experimentally generated, and after 24 hours, several features of the built turret were quantified, i.e., mass, height, number and surface area (aperture) of turret openings. Turret mass and height were similar in all experiments even when no airflow was provided in the ventilation tunnel. However, elevated CO2 levels led to the construction of a turret with several minor openings and a larger total aperture. This effect was statistically significant at higher CO2 levels of 5% and 10% but not at 1% CO2. The construction of a turret with several minor openings did not depend on the strong differences in CO2 levels between the outflowing and the outside air, since workers also built permeated turrets even when the CO2 levels inside and outside were both similarly high. We propose that the construction of turrets with several openings and larger opening surface area might facilitate the removal of CO2 from the underground nest structure and could therefore be involved in the control of nest climate in leaf-cutting ants. PMID:29145459

The construction of ventilation turrets in Atta vollenweideri leaf-cutting ants: Carbon dioxide levels in the nest tunnels, but not airflow or air humidity, influence turret structure.

PubMed

Halboth, Florian; Roces, Flavio

2017-01-01

Nest ventilation in the leaf-cutting ant Atta vollenweideri is driven via a wind-induced mechanism. On their nests, workers construct small turrets that are expected to facilitate nest ventilation. We hypothesized that the construction and structural features of the turrets would depend on the colony's current demands for ventilation and thus might be influenced by the prevailing environmental conditions inside the nest. Therefore, we tested whether climate-related parameters, namely airflow, air humidity and CO2 levels in the outflowing nest air influenced turret construction in Atta vollenweideri. In the laboratory, we simulated a semi-natural nest arrangement with fungus chambers, a central ventilation tunnel providing outflow of air and an aboveground building arena for turret construction. In independent series, different climatic conditions inside the ventilation tunnel were experimentally generated, and after 24 hours, several features of the built turret were quantified, i.e., mass, height, number and surface area (aperture) of turret openings. Turret mass and height were similar in all experiments even when no airflow was provided in the ventilation tunnel. However, elevated CO2 levels led to the construction of a turret with several minor openings and a larger total aperture. This effect was statistically significant at higher CO2 levels of 5% and 10% but not at 1% CO2. The construction of a turret with several minor openings did not depend on the strong differences in CO2 levels between the outflowing and the outside air, since workers also built permeated turrets even when the CO2 levels inside and outside were both similarly high. We propose that the construction of turrets with several openings and larger opening surface area might facilitate the removal of CO2 from the underground nest structure and could therefore be involved in the control of nest climate in leaf-cutting ants.

Usage of Nest Materials by House Sparrow (Passer domesticus) Along an Urban to Rural Gradient in Coimbatore, India.

PubMed

Radhamany, Dhanya; Das, Karumampoyil Sakthidas Anoop; Azeez, Parappurath Abdul; Wen, Longying; Sreekala, Leelambika Krishnan

2016-08-01

The house sparrow (Passer domesticus) is a widely distributed bird species found throughout the world. Being a species which has close association with humans, they chiefly nest on man-made structures. Here we describe the materials used by the house sparrow for making nests along an urban to rural gradient. For the current study, we selected the Coimbatore to Anaikatty road (State Highway-164), a 27 km inter-state highway, which traverses along an urban core to rural outstretch of Coimbatore. Of the 30 nests observed, 15 nests were from the rural, 8 were from the suburban, and 7 were from the urban areas. The nests had two distinct layers, specifically the structural layer and the inner lining. In the current study, we identified 11 plant species, 2 types of animal matter, and 6 types of anthropogenic matter, including plastic pieces and fine rope. The amount of anthropogenic materials in the nest formation varied along the gradients. The usage of anthropogenic materials was high in urban areas (p<0.05) whereas it did not differ at the sub-urban regions (p>0.05). A gradual decrease in the usage of plant matter towards the urban area was noticed (p<0.05). This study explicitly documents the links between nest material usage along an urban to rural gradient, in a human associated bird.

Habitat fragmentation reduces nest survival in an Afrotropical bird community in a biodiversity hotspot

USGS Publications Warehouse

Newmark, W.D.; Stanley, T.R.

2011-01-01

Ecologists have long hypothesized that fragmentation of tropical landscapes reduces avian nest success. However, this hypothesis has not been rigorously assessed because of the difficulty of finding large numbers of well-hidden nests in tropical forests. Here we report that in the East Usambara Mountains in Tanzania, which are part of the Eastern Arc Mountains, a global biodiversity hotspot, that daily nest survival rate and nest success for seven of eight common understory bird species that we examined over a single breeding season were significantly lower in fragmented than in continuous forest, with the odds of nest failure for these seven species ranging from 1.9 to 196.8 times higher in fragmented than continuous forest. Cup-shaped nests were particularly vulnerable in fragments. We then examined over six breeding seasons and 14 study sites in a multivariable survival analysis the influence of landscape structure and nest location on daily nest survival for 13 common species representing 1,272 nests and four nest types (plate, cup, dome, and pouch). Across species and nest types, area, distance of nest to edge, and nest height had a dominant influence on daily nest survival, with area being positively related to nest survival and distance of nest to edge and nest height being both positively and negatively associated with daily nest survival. Our results indicate that multiple environmental factors contribute to reduce nest survival within a tropical understory bird community in a fragmented landscape and that maintaining large continuous forest is important for enhancing nest survival for Afrotropical understory birds.

Habitat fragmentation reduces nest survival in an Afrotropical bird community in a biodiversity hotspot.

PubMed

Newmark, William D; Stanley, Thomas R

2011-07-12

Ecologists have long hypothesized that fragmentation of tropical landscapes reduces avian nest success. However, this hypothesis has not been rigorously assessed because of the difficulty of finding large numbers of well-hidden nests in tropical forests. Here we report that in the East Usambara Mountains in Tanzania, which are part of the Eastern Arc Mountains, a global biodiversity hotspot, that daily nest survival rate and nest success for seven of eight common understory bird species that we examined over a single breeding season were significantly lower in fragmented than in continuous forest, with the odds of nest failure for these seven species ranging from 1.9 to 196.8 times higher in fragmented than continuous forest. Cup-shaped nests were particularly vulnerable in fragments. We then examined over six breeding seasons and 14 study sites in a multivariable survival analysis the influence of landscape structure and nest location on daily nest survival for 13 common species representing 1,272 nests and four nest types (plate, cup, dome, and pouch). Across species and nest types, area, distance of nest to edge, and nest height had a dominant influence on daily nest survival, with area being positively related to nest survival and distance of nest to edge and nest height being both positively and negatively associated with daily nest survival. Our results indicate that multiple environmental factors contribute to reduce nest survival within a tropical understory bird community in a fragmented landscape and that maintaining large continuous forest is important for enhancing nest survival for Afrotropical understory birds.

Habitat fragmentation reduces nest survival in an Afrotropical bird community in a biodiversity hotspot

PubMed Central

Newmark, William D.; Stanley, Thomas R.

2011-01-01

Ecologists have long hypothesized that fragmentation of tropical landscapes reduces avian nest success. However, this hypothesis has not been rigorously assessed because of the difficulty of finding large numbers of well-hidden nests in tropical forests. Here we report that in the East Usambara Mountains in Tanzania, which are part of the Eastern Arc Mountains, a global biodiversity hotspot, that daily nest survival rate and nest success for seven of eight common understory bird species that we examined over a single breeding season were significantly lower in fragmented than in continuous forest, with the odds of nest failure for these seven species ranging from 1.9 to 196.8 times higher in fragmented than continuous forest. Cup-shaped nests were particularly vulnerable in fragments. We then examined over six breeding seasons and 14 study sites in a multivariable survival analysis the influence of landscape structure and nest location on daily nest survival for 13 common species representing 1,272 nests and four nest types (plate, cup, dome, and pouch). Across species and nest types, area, distance of nest to edge, and nest height had a dominant influence on daily nest survival, with area being positively related to nest survival and distance of nest to edge and nest height being both positively and negatively associated with daily nest survival. Our results indicate that multiple environmental factors contribute to reduce nest survival within a tropical understory bird community in a fragmented landscape and that maintaining large continuous forest is important for enhancing nest survival for Afrotropical understory birds. PMID:21709237

The effect of wind on the rate of heat loss from avian cup-shaped nests.

PubMed

Heenan, Caragh B; Seymour, Roger S

2012-01-01

Forced convection can significantly influence the heat loss from birds and their offspring but effects may be reduced by using sheltered micro-sites such as cavities or constructing nests. The structural and thermal properties of the nests of two species, the spiny-cheeked honeyeater (Acanthagenys rufogularis) and yellow-throated miner (Manorina flavigula), were measured in relation to three wind speeds. Nest dimensions differ between the two species, despite the similar body mass of the incubating adults, however nest conductance is comparable. As wind speed increases, so does the rate of heat loss from the nests of both species, and further still during incubation recesses. The significance of forced convection through the nest is a near-doubling in heat production required by the parent, even when incubating at relatively low wind speeds. This provides confirmation that selecting a sheltered nest site is important for avian reproductive success.

The Effect of Wind on the Rate of Heat Loss from Avian Cup-Shaped Nests

PubMed Central

Heenan, Caragh B.; Seymour, Roger S.

2012-01-01

Forced convection can significantly influence the heat loss from birds and their offspring but effects may be reduced by using sheltered micro-sites such as cavities or constructing nests. The structural and thermal properties of the nests of two species, the spiny-cheeked honeyeater (Acanthagenys rufogularis) and yellow-throated miner (Manorina flavigula), were measured in relation to three wind speeds. Nest dimensions differ between the two species, despite the similar body mass of the incubating adults, however nest conductance is comparable. As wind speed increases, so does the rate of heat loss from the nests of both species, and further still during incubation recesses. The significance of forced convection through the nest is a near-doubling in heat production required by the parent, even when incubating at relatively low wind speeds. This provides confirmation that selecting a sheltered nest site is important for avian reproductive success. PMID:22389689

Direct effects of cattle on grassland birds in Canada.

PubMed

Bleho, Barbara I; Koper, Nicola; Machtans, Craig S

2014-06-01

Effects of grazing on grassland birds are generally thought to be indirect, through alteration of vegetation structure; however, livestock can also affect nest survival directly through trampling and other disturbances (e.g., livestock-induced abandonment). We extracted data on nest fates from 18 grazing studies conducted in Canada. We used these data to assess rates of nest destruction by cattle among 9 ecoregions and between seasonal and rotational grazing systems. Overall, few nests were destroyed by cattle (average 1.5% of 9132 nests). Nest destruction was positively correlated with grazing pressure (i.e., stocking rate or grazing intensity), but nest survival was higher in more heavily grazed areas for some species. Because rates of destruction of grassland bird nests by cattle are low in Canada, management efforts to reduce such destruction may not be of ecological or economic value in Canada. © 2014 Society for Conservation Biology.

Nestedness of desert bat assemblages: species composition patterns in insular and terrestrial landscapes.

PubMed

Frick, Winifred F; Hayes, John P; Heady, Paul A

2009-01-01

Nested patterns of community composition exist when species at depauperate sites are subsets of those occurring at sites with more species. Nested subset analysis provides a framework for analyzing species occurrences to determine non-random patterns in community composition and potentially identify mechanisms that may shape faunal assemblages. We examined nested subset structure of desert bat assemblages on 20 islands in the southern Gulf of California and at 27 sites along the Baja California peninsula coast, the presumable source pool for the insular faunas. Nested structure was analyzed using a conservative null model that accounts for expected variation in species richness and species incidence across sites (fixed row and column totals). Associations of nestedness and island traits, such as size and isolation, as well as species traits related to mobility, were assessed to determine the potential role of differential extinction and immigration abilities as mechanisms of nestedness. Bat faunas were significantly nested in both the insular and terrestrial landscape and island size was significantly correlated with nested structure, such that species on smaller islands tended to be subsets of species on larger islands, suggesting that differential extinction vulnerabilities may be important in shaping insular bat faunas. The role of species mobility and immigration abilities is less clearly associated with nestedness in this system. Nestedness in the terrestrial landscape is likely due to stochastic processes related to random placement of individuals and this may also influence nested patterns on islands, but additional data on abundances will be necessary to distinguish among these potential mechanisms.

Multiple imputation of missing data in nested case-control and case-cohort studies.

PubMed

Keogh, Ruth H; Seaman, Shaun R; Bartlett, Jonathan W; Wood, Angela M

2018-06-05

The nested case-control and case-cohort designs are two main approaches for carrying out a substudy within a prospective cohort. This article adapts multiple imputation (MI) methods for handling missing covariates in full-cohort studies for nested case-control and case-cohort studies. We consider data missing by design and data missing by chance. MI analyses that make use of full-cohort data and MI analyses based on substudy data only are described, alongside an intermediate approach in which the imputation uses full-cohort data but the analysis uses only the substudy. We describe adaptations to two imputation methods: the approximate method (MI-approx) of White and Royston () and the "substantive model compatible" (MI-SMC) method of Bartlett et al. (). We also apply the "MI matched set" approach of Seaman and Keogh () to nested case-control studies, which does not require any full-cohort information. The methods are investigated using simulation studies and all perform well when their assumptions hold. Substantial gains in efficiency can be made by imputing data missing by design using the full-cohort approach or by imputing data missing by chance in analyses using the substudy only. The intermediate approach brings greater gains in efficiency relative to the substudy approach and is more robust to imputation model misspecification than the full-cohort approach. The methods are illustrated using the ARIC Study cohort. Supplementary Materials provide R and Stata code. © 2018, The International Biometric Society.

Genetic structure of Florida green turtle rookeries as indicated by mitochondrial DNA control region sequences

USGS Publications Warehouse

Shamblin, Brian M.; Bagley, Dean A.; Ehrhart, Llewellyn M.; Desjardin, Nicole A.; Martin, R. Erik; Hart, Kristen M.; Naro-Maciel, Eugenia; Rusenko, Kirt; Stiner, John C.; Sobel, Debra; Johnson, Chris; Wilmers, Thomas; Wright, Laura J.; Nairn, Campbell J.

2014-01-01

Green turtle (Chelonia mydas) nesting has increased dramatically in Florida over the past two decades, ranking the Florida nesting aggregation among the largest in the Greater Caribbean region. Individual beaches that comprise several hundred kilometers of Florida’s east coast and Keys support tens to thousands of nests annually. These beaches encompass natural to highly developed habitats, and the degree of demographic partitioning among rookeries was previously unresolved. We characterized the genetic structure of ten Florida rookeries from Cape Canaveral to the Dry Tortugas through analysis of 817 base pair mitochondrial DNA (mtDNA) control region sequences from 485 nesting turtles. Two common haplotypes, CM-A1.1 and CM-A3.1, accounted for 87 % of samples, and the haplotype frequencies were strongly partitioned by latitude along Florida’s Atlantic coast. Most genetic structure occurred between rookeries on either side of an apparent genetic break in the vicinity of the St. Lucie Inlet that separates Hutchinson Island and Jupiter Island, representing the finest scale at which mtDNA structure has been documented in marine turtle rookeries. Florida and Caribbean scale analyses of population structure support recognition of at least two management units: central eastern Florida and southern Florida. More thorough sampling and deeper sequencing are necessary to better characterize connectivity among Florida green turtle rookeries as well as between the Florida nesting aggregation and others in the Greater Caribbean region.

Grassland bird productivity in warm season grass fields in southwest Wisconsin

USGS Publications Warehouse

Byers, Carolyn M.; Ribic, Christine; Sample, David W.; Dadisman, John D.; Guttery, Michael

2017-01-01

Surrogate grasslands established through federal set-aside programs, such as U.S. Department of Agriculture's Conservation Reserve Program (CRP), provide important habitat for grassland birds. Warm season grass CRP fields as a group have the potential for providing a continuum of habitat structure for breeding birds, depending on how the fields are managed and their floristic composition. We studied the nesting activity of four obligate grassland bird species, Bobolink (Dolichonyx oryzivorus), Eastern Meadowlark (Sturnella magna), Grasshopper Sparrow (Ammodramus savannarum), and Henslow's Sparrow (A. henslowii), in relation to vegetative composition and fire management in warm season CRP fields in southwest Wisconsin during 2009–2011. Intraspecific variation in apparent nest density was related to the number of years since the field was burned. Apparent Grasshopper Sparrow nest density was highest in the breeding season immediately following spring burns, apparent Henslow's Sparrow nest density was highest 1 y post burn, and apparent Bobolink and Eastern Meadowlark nest densities were higher in post fire years one to three. Grasshopper Sparrow nest density was highest on sites with more diverse vegetation, specifically prairie forbs, and on sites with shorter less dense vegetation. Bobolink, Eastern Meadowlark, and Henslow's Sparrow apparent nest densities were higher on sites with deeper litter; litter was the vegetative component that was most affected by spring burns. Overall nest success was 0.487 for Bobolink (22 d nesting period), 0.478 for Eastern Meadowlark (25 d nesting period), 0.507 for Grasshopper Sparrow (22 d nesting period), and 0.151 for Henslow's Sparrow (21 d nesting period). The major nest predators were grassland-associated species: thirteen-lined ground squirrel (Ictidomys tridecemlineatus), striped skunk (Mephitis mephitis), milk snake (Lampropeltis triangulum), American badger (Taxidea taxus), and western fox snake (Elaphe vulpina). Overall depredation rate was not affected by the number of years since the site had been burned. The diversity of vegetation on warm season CRP fields created by management using fire provides a continuum of structure for obligate grassland birds to use for breeding and habitat for a diversity of nest predators.

A Methodological Review of Statistical Methods for Handling Multilevel Non-Nested Longitudinal Data in Educational Research

ERIC Educational Resources Information Center

Sun, Shuyan; Pan, Wei

2014-01-01

As applications of multilevel modelling in educational research increase, researchers realize that multilevel data collected in many educational settings are often not purely nested. The most common multilevel non-nested data structure is one that involves student mobility in longitudinal studies. This article provides a methodological review of…

Nestly--a framework for running software with nested parameter choices and aggregating results.

PubMed

McCoy, Connor O; Gallagher, Aaron; Hoffman, Noah G; Matsen, Frederick A

2013-02-01

The execution of a software application or pipeline using various combinations of parameters and inputs is a common task in bioinformatics. In the absence of a specialized tool to organize, streamline and formalize this process, scientists must write frequently complex scripts to perform these tasks. We present nestly, a Python package to facilitate running tools with nested combinations of parameters and inputs. nestly provides three components. First, a module to build nested directory structures corresponding to choices of parameters. Second, the nestrun script to run a given command using each set of parameter choices. Third, the nestagg script to aggregate results of the individual runs into a CSV file, as well as support for more complex aggregation. We also include a module for easily specifying nested dependencies for the SCons build tool, enabling incremental builds. Source, documentation and tutorial examples are available at http://github.com/fhcrc/nestly. nestly can be installed from the Python Package Index via pip; it is open source (MIT license).

A comparison of burn season effects on nesting birds in North Dakota mixed-grass prairie

USGS Publications Warehouse

Higgins, K.F.

1986-01-01

During 1982-1985, the effects of single spring and fall burn treatments on ground nesting birds and residual cover were studied on five paired areas of native mixed-grass prairie in northwestern Stutsman County, ND. Annually, visual obstruction readings to index the height-density of residual cover were taken once and nest searches were made four times on each area. Residual nesting cover on fall burn plots averaged taller and denser than on spring burn plots during post-fire growing years 2-4. A total of 259 duck nests and 63 nests of non-passerine birds were found during the four years. Duck nesting success was significantly greater (P < 0.05) in fall burn plots than in spring burn plots for all species and years combined. Too few nests of other bird species were found for valid comparisons. Results suggest that vegetation structure and duck nesting response to spring and fall burns became similar again by the third post-fire growing season.

Habitat selection responses of parents to offspring predation risk: An experimental test

USGS Publications Warehouse

Fontaine, J.J.; Martin, T.E.

2006-01-01

The ability of nest predation to influence habitat settlement decisions in birds is widely debated, despite its importance in limiting fitness. Here, we experimentally manipulated nest predation risk across a landscape and asked the question, do migratory birds assess and respond to variation in nest predation risk when choosing breeding habitats? We examined habitat preference by quantifying the density and settlement date of eight species of migratory passerines breeding in areas with and without intact nest predator communities. We found consistently more individuals nesting in areas with reduced nest predation than in areas with intact predator assemblages, although predation risk had no influence on settlement or breeding phenology. Additionally, those individuals occupying safer nesting habitats exhibited increased singing activity. These findings support a causal relationship between habitat choice and nest predation risk and suggest the importance of nest predation risk in shaping avian community structure and breeding activity. ?? 2006 by The University of Chicago. All rights reserved.

Nest Records of Wreathed Hornbill (Rhyticeros undulates) in Gunung Gentong Station, Mount Ungaran Central Java

NASA Astrophysics Data System (ADS)

Rahayuningsih, M.; Kartijomo, NE; Retnaningsih, A.; Munir, M.; Dahlan, J.

2017-04-01

The remaining forest of Mount Ungaran, Central Javais the suitable habitat of Wreathed Hornbill (Rhyticeros undulatus), especially for a nesting site. The objective of the study was to analyse the nest record and characteristics of habitat around the nest, especially in Gunung Gentong station. The research was conducted from 2010-2016 using exploration method. The methodhabitat profile of the vertical structure tree canopy was taken by plot size 60 × 20 m. Measurements were taken to the standing of vegetation, canopy closure, the direction of the canopy, height canopy, a former branch of the vegetation height, and stem diameter. The Result of the study showed that Gunung Gentong is one of the research station that we have been recorded for nesting site on 2010-2015. Atotal of the nest record on Gunung Genting station was 10 nests. Estimate the elevation of nest location between 939-1240 AMSL. The tree species that used for nesting was Syzygium glabatrum, Syzygium antisepticum, Ceratoxylon formosum, and Ficus sp

Phenotypic integration in an extended phenotype: among-individual variation in nest-building traits of the alfalfa leafcutting bee (Megachile rotundata).

PubMed

Royauté, Raphaël; Wilson, Elisabeth S; Helm, Bryan R; Mallinger, Rachel E; Prasifka, Jarrad; Greenlee, Kendra J; Bowsher, Julia H

2018-03-02

Structures such as nests and burrows are an essential component of many organisms' life-cycle and require a complex sequence of behaviours. Because behaviours can vary consistently among individuals and be correlated with one another, we hypothesized that these structures would (1) show evidence of among-individual variation, (2) be organized into distinct functional modules and (3) show evidence of trade-offs among functional modules due to limits on energy budgets. We tested these hypotheses using the alfalfa leafcutting bee, Megachile rotundata, a solitary bee and important crop pollinator. Megachile rotundata constructs complex nests by gathering leaf materials to form a linear series of cells in pre-existing cavities. In this study, we examined variation in the following nest construction traits: reproduction (number of cells per nest and nest length), nest protection (cap length and number of leaves per cap), cell construction (cell size and number of leaves per cell) and cell provisioning (cell mass) from 60 nests. We found a general decline in investment in cell construction and provisioning with each new cell built. In addition, we found evidence for both repeatability and plasticity in cell provisioning with little evidence for trade-offs among traits. Instead, most traits were positively, albeit weakly, correlated (r ~ 0.15), and traits were loosely organized into covarying modules. Our results show that individual differences in nest construction are detectable at a level similar to that of other behavioural traits and that these traits are only weakly integrated. This suggests that nest components are capable of independent evolutionary trajectories. © 2018 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2018 European Society For Evolutionary Biology.

An Enhanced Memetic Algorithm for Single-Objective Bilevel Optimization Problems.

PubMed

Islam, Md Monjurul; Singh, Hemant Kumar; Ray, Tapabrata; Sinha, Ankur

2017-01-01

Bilevel optimization, as the name reflects, deals with optimization at two interconnected hierarchical levels. The aim is to identify the optimum of an upper-level  leader problem, subject to the optimality of a lower-level follower problem. Several problems from the domain of engineering, logistics, economics, and transportation have an inherent nested structure which requires them to be modeled as bilevel optimization problems. Increasing size and complexity of such problems has prompted active theoretical and practical interest in the design of efficient algorithms for bilevel optimization. Given the nested nature of bilevel problems, the computational effort (number of function evaluations) required to solve them is often quite high. In this article, we explore the use of a Memetic Algorithm (MA) to solve bilevel optimization problems. While MAs have been quite successful in solving single-level optimization problems, there have been relatively few studies exploring their potential for solving bilevel optimization problems. MAs essentially attempt to combine advantages of global and local search strategies to identify optimum solutions with low computational cost (function evaluations). The approach introduced in this article is a nested Bilevel Memetic Algorithm (BLMA). At both upper and lower levels, either a global or a local search method is used during different phases of the search. The performance of BLMA is presented on twenty-five standard test problems and two real-life applications. The results are compared with other established algorithms to demonstrate the efficacy of the proposed approach.

A multi-scale approach of fluvial biogeomorphic dynamics using photogrammetry.

PubMed

Hortobágyi, Borbála; Corenblit, Dov; Vautier, Franck; Steiger, Johannes; Roussel, Erwan; Burkart, Andreas; Peiry, Jean-Luc

2017-11-01

Over the last twenty years, significant technical advances turned photogrammetry into a relevant tool for the integrated analysis of biogeomorphic cross-scale interactions within vegetated fluvial corridors, which will largely contribute to the development and improvement of self-sustainable river restoration efforts. Here, we propose a cost-effective, easily reproducible approach based on stereophotogrammetry and Structure from Motion (SfM) technique to study feedbacks between fluvial geomorphology and riparian vegetation at different nested spatiotemporal scales. We combined different photogrammetric methods and thus were able to investigate biogeomorphic feedbacks at all three spatial scales (i.e., corridor, alluvial bar and micro-site) and at three different temporal scales, i.e., present, recent past and long term evolution on a diversified riparian landscape mosaic. We evaluate the performance and the limits of photogrammetric methods by targeting a set of fundamental parameters necessary to study biogeomorphic feedbacks at each of the three nested spatial scales and, when possible, propose appropriate solutions. The RMSE varies between 0.01 and 2 m depending on spatial scale and photogrammetric methods. Despite some remaining difficulties to properly apply them with current technologies under all circumstances in fluvial biogeomorphic studies, e.g. the detection of vegetation density or landform topography under a dense vegetation canopy, we suggest that photogrammetry is a promising instrument for the quantification of biogeomorphic feedbacks at nested spatial scales within river systems and for developing appropriate river management tools and strategies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Why are there more arboreal ant species in primary than in secondary tropical forests?

PubMed

Klimes, Petr; Idigel, Cliffson; Rimandai, Maling; Fayle, Tom M; Janda, Milan; Weiblen, George D; Novotny, Vojtech

2012-09-01

1. Species diversity of arboreal arthropods tends to increase during rainforest succession so that primary forest communities comprise more species than those from secondary vegetation, but it is not well understood why. Primary forests differ from secondary forests in a wide array of factors whose relative impacts on arthropod diversity have not yet been quantified. 2. We assessed the effects of succession-related determinants on a keystone ecological group, arboreal ants, by conducting a complete census of 1332 ant nests from all trees with diameter at breast height ≥ 5 cm occurring within two (unreplicated) 0·32-ha plots, one in primary and one in secondary lowland forest in New Guinea. Specifically, we used a novel rarefaction-based approach to match number, size distribution and taxonomic structure of trees in primary forest communities to those in secondary forest and compared the resulting numbers of ant species. 3. In total, we recorded 80 nesting ant species from 389 trees in primary forest but only 42 species from 295 trees in secondary forest. The two habitats did not differ in the mean number of ant species per tree or in the relationship between ant diversity and tree size. However, the between-tree similarity of ant communities was higher in secondary forest than in primary forest, as was the between-tree nest site similarity, suggesting that secondary trees were more uniform in providing nesting microhabitats. 4. Using our rarefaction method, the difference in ant species richness between two forest types was partitioned according to the effects of higher tree density (22·6%), larger tree size (15·5%) and higher taxonomic diversity of trees (14·3%) in primary than in secondary forest. The remaining difference (47·6%) was because of higher beta diversity of ant communities between primary forest trees. In contrast, difference in nest density was explained solely by difference in tree density. 5. Our study shows that reduction in plant taxonomic diversity in secondary forests is not the main driver of the reduction in canopy ant species richness. We suggest that the majority of arboreal species losses in secondary tropical forests are attributable to simpler vegetation structure, combined with lower turnover of nesting microhabitats between trees. © 2012 The Authors. Journal of Animal Ecology © 2012 British Ecological Society.

Influence of olfactory and visual cover on nest site selection and nest success for grassland-nesting birds.

PubMed

Fogarty, Dillon T; Elmore, R Dwayne; Fuhlendorf, Samuel D; Loss, Scott R

2017-08-01

Habitat selection by animals is influenced by and mitigates the effects of predation and environmental extremes. For birds, nest site selection is crucial to offspring production because nests are exposed to extreme weather and predation pressure. Predators that forage using olfaction often dominate nest predator communities; therefore, factors that influence olfactory detection (e.g., airflow and weather variables, including turbulence and moisture) should influence nest site selection and survival. However, few studies have assessed the importance of olfactory cover for habitat selection and survival. We assessed whether ground-nesting birds select nest sites based on visual and/or olfactory cover. Additionally, we assessed the importance of visual cover and airflow and weather variables associated with olfactory cover in influencing nest survival. In managed grasslands in Oklahoma, USA, we monitored nests of Northern Bobwhite ( Colinus virginianus ), Eastern Meadowlark ( Sturnella magna ), and Grasshopper Sparrow ( Ammodramus savannarum ) during 2015 and 2016. To assess nest site selection, we compared cover variables between nests and random points. To assess factors influencing nest survival, we used visual cover and olfactory-related measurements (i.e., airflow and weather variables) to model daily nest survival. For nest site selection, nest sites had greater overhead visual cover than random points, but no other significant differences were found. Weather variables hypothesized to influence olfactory detection, specifically precipitation and relative humidity, were the best predictors of and were positively related to daily nest survival. Selection for overhead cover likely contributed to mitigation of thermal extremes and possibly reduced detectability of nests. For daily nest survival, we hypothesize that major nest predators focused on prey other than the monitored species' nests during high moisture conditions, thus increasing nest survival on these days. Our study highlights how mechanistic approaches to studying cover informs which dimensions are perceived and selected by animals and which dimensions confer fitness-related benefits.

Nestedness in assemblages of helminth parasites of bats: a function of geography, environment, or host nestedness?

PubMed

Warburton, Elizabeth M; Van Der Mescht, Luther; Khokhlova, Irina S; Krasnov, Boris R; Vonhof, Maarten J

2018-05-01

Nested subsets occur in ecological communities when species-poor communities are subsets of larger, species-rich communities. Understanding this pattern can help elucidate species colonization abilities, extinction risks, and general structuring of biological communities. Here, we evaluate nestedness in a poorly studied host-parasite system, bats and their helminths, across the Japanese archipelago and within its different bioclimatic regions. We hypothesized that (1) if helminth communities are nested across geographic sites at the level of the archipelago, then broad-scale processes, like colonization-extinction dynamics, mainly structure parasite assemblages; (2) if helminth communities are nested across geographic sites at the level of the bioclimatic region, then fine-scale environmental variation plays a significant role in species nestedness; (3) if helminth community nestedness mirrors host species nestedness, then communities are nested because the habitats they occupy are nested; and (4) if nestedness does not occur or if it is not correlated with any geographical or host data, then passive sampling could be responsible for the patterns of parasite assemblage in our sample. We found that helminth communities were nested across host species throughout the archipelago but, when considering each bioclimatic region, helminths in only one region were significantly more nested than the null model. Helminth communities were also nested across sites within all four bioclimatic regions. These results suggest that helminths form nested subsets across the archipelago due to broad-scale processes that reflect the overall lineages of their mammalian hosts; however, at the regional scale, environmental processes related to nestedness of their habitats drive parasite community nestedness.

First description of the nest, eggs, and breeding behavior of the Mérida Tapaculo (Scytalopus meridanus)

USGS Publications Warehouse

Decker, Karie L.; Niklison, Alina M.; Martin, Thomas E.

2007-01-01

We provide the first description of the nest, eggs, and breeding behavior of the Mérida Tapaculo (Scytalopus meridanus). Data are from one pair in the moist cloud forest of Yacambu National Park, Venezuela during April–May 2004. Two nests, constructed by the same pair, were globular in structure and consisted of mossy material placed in a rock crevice of a muddy rock wall. The eggs were cream colored with an average mass of 4.19 g. Clutch sizes were one in the first nest and two in the second. The species showed bi-parental care in nest building and incubation. Nest attentiveness (percent time spent on the nest incubating) averaged 83.4 ± 14% (SD). Average on and off bouts were 33.24 and 6.34 min, respectively.

Terrestrial nest-building by wild chimpanzees (Pan troglodytes): implications for the tree-to-ground sleep transition in early hominins.

PubMed

Koops, Kathelijne; McGrew, William C; Matsuzawa, Tetsuro; Knapp, Leslie A

2012-07-01

Nest-building is a great ape universal and arboreal nesting in chimpanzees and bonobos suggests that the common ancestor of Pan and Homo also nested in trees. It has been proposed that arboreal nest-building remained the prevailing pattern until Homo erectus, a fully terrestrial biped, emerged. We investigated the unusual occurrence of ground-nesting in chimpanzees (Pan troglodytes), which may inform on factors influencing the tree-to-ground sleep transition in the hominin lineage. We used a novel genetic approach to examine ground-nesting in unhabituated chimpanzees at Seringbara in the Nimba Mountains, Guinea. Previous research showed that ground-nesting at Seringbara was not ecologically determined. Here, we tested a possible mate-guarding function of ground-nesting by analyzing DNA from shed hairs collected from ground nests and tree nests found in close proximity. We examined whether or not ground-nesting was a group-level behavioral pattern and whether or not it occurred in more than one community. We used multiple genetic markers to identify sex and to examine variation in mitochondrial DNA control region (HV1, HV2) sequences. Ground-nesting was a male-biased behavior and males constructed more elaborate ("night") nests than simple ("day") nests on the ground. The mate-guarding hypothesis was not supported, as ground and associated tree nests were built either by maternally-related males or possibly by the same individuals. Ground-nesting was widespread and likely habitual in two communities. We suggest that terrestrial nest-building may have already occurred in arboreally-adapted early hominins before the emergence of H. erectus. Copyright © 2012 Wiley Periodicals, Inc.

Inter-seasonal maintenance of individual nest site preferences in hawksbill sea turtles.

PubMed

Kamel, Stephanie J; Mrosovsky, N

2006-11-01

Within a single population of hawksbill sea turtles (Eretmochelys imbricata), we found a behavioral polymorphism for maternal nest site choice with respect to beach microhabitat characteristics. Some females preferred to nest in littoral forest and in places with overstory vegetation cover, and others preferred to nest in more open, deforested areas. Nest site choice was consistent within and between nesting seasons two years apart. This was not a result of females simply returning to the same location along the shoreline; beach sections used by individual turtles varied between seasons. Nest site choice was not influenced by changes in beach environment (e.g., beach width and foliage cover) or by changes in females' reproductive output (e.g., clutch size), suggesting that fidelity to particular microhabitats is a major determinant of the observed nesting patterns. Because hawksbills exhibit temperature-dependent sex determination, if the behavioral polymorphism in nest site choice has a genetic basis, as is plausible, then this would have implications for sex ratio evolution and offspring survival. By taking an individual-based approach to the study of maternal behavior we reveal previously overlooked individual variation and hope to provide some impetus for more detailed studies of nest site choice.

Phenotypic integration in an extended phenotype: among-individual variation in nest-building traits of the alfalfa leafcutting bee (Megachile rotundata)

USDA-ARS?s Scientific Manuscript database

Structures such as nests and burrows are an essential component of many organisms’ life-cycle and requires a complex sequence of behaviors. Because behaviors can vary consistently among individuals and be correlated with one another, we hypothesized that these structures would 1) show evidence of am...

Association of weather and nest-site structure with reproductive success in California spotted owls

Treesearch

Malcolm North; George Steger; Renee Denton; Gary Eberlein; Tom Munton; Ken Johnson

2000-01-01

Although the spotted owl (Strix occidentalis) has been intensively studied, factors influencing its reproduction are not well understood. We examined a 9-year demographic study of 51-86 pairs of the California spotted owl (S. o. occidentalis), weather conditions, and forest structure at nest sites in oak (Quercus sp.) woodland and...

Contrasting nest survival patterns for ducks and songbirds in northern mixed-grass prairie

USGS Publications Warehouse

Grant, Todd; Shaffer, Terry L.; Madden, Elizabeth M.; Nenneman, Melvin P.

2017-01-01

Management actions intended to protect or improve habitat for ducks may benefit grassland-nesting passerines, but scant information is available to explore this assumption. During 1998–2003, we examined nest survival of ducks and songbirds to determine whether effects of prescribed fire and other habitat features (e.g., shrub cover and distance to habitat edges) were similar for ducks and passerines breeding in North Dakota. We used the logistic-exposure method to estimate survival of duck and songbird nests (n = 3,171). We used an information-theoretic approach to identify factors that most influenced nest survival. Patterns of nest survival were markedly different between taxonomic groups. For ducks, nest survival was greater during the first postfire nesting season (daily survival rate [DSR] = 0.957, 85% CI = 0.951–0.963), relative to later postfire nesting seasons (DSR = 0.946, 85% CI = 0.942–0.950). Furthermore duck nest survival and nest densities were inversely related. Duck nest survival also was greater as shrub cover decreased and as distance from cropland and wetland edges increased. Passerines had lower nest survival during the first postfire nesting season (DSR = 0.934, 85% CI = 0.924–0.944), when densities also were low compared to subsequent postfire nesting seasons (DSR = 0.947, 85% CI = 0.944–0.950). Parasitism by brown-headed cowbirds (Molothrus ater) reduced passerine nest survival and this effect was more pronounced during the first postfire nesting season compared to subsequent nesting seasons. Passerine nest survival was greater as shrub cover decreased and perhaps for more concealed nests. Duck and songbird nest survival rates were not correlated during this study and for associated studies that examined additional variables using the same dataset, suggesting that different mechanisms influenced their survival. Based on our results, ducks should not be considered direct surrogates for passerines when predicting effects of prescribed fire, shrub cover, and habitat edges on nest survival.

Semi-arid grassland bird responses to patch-burn grazing and drought

USGS Publications Warehouse

Skagen, Susan K.; Augustine, David J.; Derner, Justin D.

2018-01-01

As grassland birds of central North America experience steep population declines with changes in land use, management of remaining tracts becomes increasingly important for population viability. The integrated use of fire and grazing may enhance vegetation heterogeneity and diversity in breeding birds, but the subsequent effects on reproduction are unknown. We examined the influence of patch-burn grazing management in shortgrass steppe in eastern Colorado on habitat use and reproductive success of 3 grassland bird species, horned lark (Eremophila alpestris), lark bunting (Calamospiza melanocorys), and McCown’s longspur (Rhynchophanes mccownii), at several spatial scales during 2011 and 2012. Although no simple direct relationship to patch-burn grazing treatment existed, habitat selection depended on precipitation- and management-induced vegetation conditions and spatial scale. All species selected taller-than-expected vegetation at the nest site, whereas at the territory scale, horned larks and McCown’s longspurs selected areas with low vegetation height and sparse cover of tall plants (taller than the dominant shortgrasses). Buntings nested primarily in unburned grassland under average rainfall. Larks and longspurs shifted activity from patch burns during average precipitation (2011) to unburned pastures during drought (2012). Daily survival rate (DSR) of nests varied with time in season, species, weather, and vegetation structure. Daily survival rate of McCown’s longspur nests did not vary with foliar cover of relatively tall vegetation at the nest under average precipitation but declined with increasing cover during drought. At the 200-m scale, increasing cover of shortgrasses, rather than taller plant species, improved DSR of larks and longspurs. These birds experience tradeoffs in the selection of habitat at different spatial scales: tall structure at nests may reduce visual detection by predators and provide protection from sun, wind, and rain, yet taller structure surrounding territories may host nest predators. Patch-burn grazing management in combination with other strategies that retain taller-structured vegetation may help sustain a diversity of breeding habitats for shortgrass birds under varying weather conditions.

Hierarchical structure of the Sicilian goats revealed by Bayesian analyses of microsatellite information.

PubMed

Siwek, M; Finocchiaro, R; Curik, I; Portolano, B

2011-02-01

Genetic structure and relationship amongst the main goat populations in Sicily (Girgentana, Derivata di Siria, Maltese and Messinese) were analysed using information from 19 microsatellite markers genotyped on 173 individuals. A posterior Bayesian approach implemented in the program STRUCTURE revealed a hierarchical structure with two clusters at the first level (Girgentana vs. Messinese, Derivata di Siria and Maltese), explaining 4.8% of variation (amovaФ(ST) estimate). Seven clusters nested within these first two clusters (further differentiations of Girgentana, Derivata di Siria and Maltese), explaining 8.5% of variation (amovaФ(SC) estimate). The analyses and methods applied in this study indicate their power to detect subtle population structure. © 2010 The Authors, Animal Genetics © 2010 Stichting International Foundation for Animal Genetics.

Effect of nest characteristics on thermal properties, clutch size, and reproductive performance for an open-cup nesting songbird

Treesearch

Michael E. Akresh; Daniel R. Ardia; David I. King

2017-01-01

Maintaining avian eggs and young at optimum temperatures for development can increase hatching success and nestling condition, but this maintenance requires parental energetic demands. Bird nests, which often provide a structure to safely hold the eggs and nestlings and protect them from predators, can additionally be designed to help maintain eggs' optimum...

Nesting characteristics of mourning doves in central New Mexico: Response to riparian forest change

Treesearch

D. Max Smith; Deborah M. Finch; David L. Hawksworth

2012-01-01

Riparian forests of the American Southwest are especially prone to changes in composition and structure due to natural and anthropogenic factors. To determine how breeding mourning doves (Zenaida macroura) respond to these changes, we examined nest site use and nest survival in control plots, fuel reduction plots before and after mechanical thinning, and post-wildfire...

34. THE CROW'S NEST. IN THE EARLY YEARS OF THE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

34. THE CROW'S NEST. IN THE EARLY YEARS OF THE INN MUSICIANS SAT AND PLAYED FOR THE GUESTS IN THE LOBBY BELOW. THE EARTHQUAKE IN 1959 CAUSED SOME STRUCTURAL DAMAGE AND NOW THE CROW'S NEST IS NOT ACCESSIBLE TO THE PUBLIC. - Old Faithful Inn, 900' northeast of Snowlodge & 1050' west of Old Faithful Lodge, Lake, Teton County, WY

Nest trampling and ground nesting birds: Quantifying temporal and spatial overlap between cattle activity and breeding redshank.

PubMed

Sharps, Elwyn; Smart, Jennifer; Mason, Lucy R; Jones, Kate; Skov, Martin W; Garbutt, Angus; Hiddink, Jan G

2017-08-01

Conservation grazing for breeding birds needs to balance the positive effects on vegetation structure and negative effects of nest trampling. In the UK, populations of Common redshank Tringa totanus breeding on saltmarshes declined by >50% between 1985 and 2011. These declines have been linked to changes in grazing management. The highest breeding densities of redshank on saltmarshes are found in lightly grazed areas. Conservation initiatives have encouraged low-intensity grazing at <1 cattle/ha, but even these levels of grazing can result in high levels of nest trampling. If livestock distribution is not spatially or temporally homogenous but concentrated where and when redshank breed, rates of nest trampling may be much higher than expected based on livestock density alone. By GPS tracking cattle on saltmarshes and monitoring trampling of dummy nests, this study quantified (i) the spatial and temporal distribution of cattle in relation to the distribution of redshank nesting habitats and (ii) trampling rates of dummy nests. The distribution of livestock was highly variable depending on both time in the season and the saltmarsh under study, with cattle using between 3% and 42% of the saltmarsh extent and spending most their time on higher elevation habitat within 500 m of the sea wall, but moving further onto the saltmarsh as the season progressed. Breeding redshank also nest on these higher elevation zones, and this breeding coincides with the early period of grazing. Probability of nest trampling was correlated to livestock density and was up to six times higher in the areas where redshank breed. This overlap in both space and time of the habitat use of cattle and redshank means that the trampling probability of a nest can be much higher than would be expected based on standard measures of cattle density. Synthesis and applications : Because saltmarsh grazing is required to maintain a favorable vegetation structure for redshank breeding, grazing management should aim to keep livestock away from redshank nesting habitat between mid-April and mid-July when nests are active, through delaying the onset of grazing or introducing a rotational grazing system.

High-field superconducting nested coil magnet

NASA Technical Reports Server (NTRS)

Laverick, C.; Lobell, G. M.

1970-01-01

Superconducting magnet, employed in conjunction with five types of superconducting cables in a nested solenoid configuration, produces total, central magnetic field strengths approaching 70 kG. The multiple coils permit maximum information on cable characteristics to be gathered from one test.

Decoration Increases the Conspicuousness of Raptor Nests

PubMed Central

Canal, David; Mulero-Pázmány, Margarita; Negro, Juan José; Sergio, Fabrizio

2016-01-01

Avian nests are frequently concealed or camouflaged, but a number of species builds noticeable nests or use conspicuous materials for nest decoration. In most cases, nest decoration has a role in mate choice or provides thermoregulatory or antiparasitic benefits. In territorial species however, decorations may serve additional or complementary functions, such as extended phenotypic signaling of nest-site occupancy and social status to potential intruders. The latter may benefit both signaler and receiver by minimizing the risk of aggressive interactions, especially in organisms with dangerous weaponry. Support for this hypothesis was recently found in a population of black kites (Milvus migrans), a territorial raptor that decorates its nest with white artificial materials. However, the crucial assumption that nest decorations increased nest-site visibility to conspecifics was not assessed, a key aspect given that black kite nests may be well concealed within the canopy. Here, we used an unmanned aircraft system to take pictures of black kite nests, with and without an experimentally placed decoration, from different altitudes and distances simulating the perspective of a flying and approaching, prospecting intruder. The pictures were shown to human volunteers through a standardized routine to determine whether detection rates varied according the nest decoration status and distance. Decorated nests consistently showed a higher detection frequency and a lower detection-latency, compared to undecorated versions of the same nests. Our results confirm that nest decoration in this species may act as a signaling medium that enhances nest visibility for aerial receivers, even at large distances. This finding complements previous work on this communication system, which showed that nest decoration was a threat informing trespassing conspecifics on the social dominance, territory quality and fighting capabilities of the signaler. PMID:27455066

Decoration Increases the Conspicuousness of Raptor Nests.

PubMed

Canal, David; Mulero-Pázmány, Margarita; Negro, Juan José; Sergio, Fabrizio

2016-01-01

Avian nests are frequently concealed or camouflaged, but a number of species builds noticeable nests or use conspicuous materials for nest decoration. In most cases, nest decoration has a role in mate choice or provides thermoregulatory or antiparasitic benefits. In territorial species however, decorations may serve additional or complementary functions, such as extended phenotypic signaling of nest-site occupancy and social status to potential intruders. The latter may benefit both signaler and receiver by minimizing the risk of aggressive interactions, especially in organisms with dangerous weaponry. Support for this hypothesis was recently found in a population of black kites (Milvus migrans), a territorial raptor that decorates its nest with white artificial materials. However, the crucial assumption that nest decorations increased nest-site visibility to conspecifics was not assessed, a key aspect given that black kite nests may be well concealed within the canopy. Here, we used an unmanned aircraft system to take pictures of black kite nests, with and without an experimentally placed decoration, from different altitudes and distances simulating the perspective of a flying and approaching, prospecting intruder. The pictures were shown to human volunteers through a standardized routine to determine whether detection rates varied according the nest decoration status and distance. Decorated nests consistently showed a higher detection frequency and a lower detection-latency, compared to undecorated versions of the same nests. Our results confirm that nest decoration in this species may act as a signaling medium that enhances nest visibility for aerial receivers, even at large distances. This finding complements previous work on this communication system, which showed that nest decoration was a threat informing trespassing conspecifics on the social dominance, territory quality and fighting capabilities of the signaler.

Is it safe to nest near conspicuous neighbours? Spatial patterns in predation risk associated with the density of American Golden-Plover nests

PubMed Central

Trottier-Paquet, Myriam; Bêty, Joël; Lamarre, Vincent; Lecomte, Nicolas

2016-01-01

Predation is one of the main factors explaining nesting mortality in most bird species. Birds can avoid nest predation or reduce predation pressure by breeding at higher latitude, showing anti-predator behaviour, selecting nest sites protected from predators, and nesting in association with protective species. American Golden-Plovers (Pluvialis dominica) defend their territory by using various warning and distraction behaviours displayed at varying levels of intensity (hereafter “conspicuous behaviour”), as well as more aggressive behaviours such as aerial attacks, but only in some populations. Such antipredator behaviour has the potential to repel predators and thus benefit the neighbouring nests by decreasing their predation risk. Yet, conspicuous behaviour could also attract predators by signalling the presence of a nest. To test for the existence of a protective effect associated with the conspicuous antipredator behaviour of American Golden-Plovers, we studied the influence of proximity to plover nests on predation risk of artificial nests on Igloolik Island (Nunavut, Canada) in July 2014. We predicted that the predation risk of artificial nests would decrease with proximity to and density of plover nests. We monitored 18 plover nests and set 35 artificial nests at 30, 50, 100, 200, and 500 m from seven of those plover nests. We found that the predation risk of artificial nests increases with the density of active plover nests. We also found a significant negative effect of the distance to the nearest active protector nest on predation risk of artificial nests. Understanding how the composition and structure of shorebird communities generate spatial patterns in predation risks represents a key step to better understand the importance of these species of conservation concern in tundra food webs. PMID:27602257

Is it safe to nest near conspicuous neighbours? Spatial patterns in predation risk associated with the density of American Golden-Plover nests.

PubMed

Giroux, Marie-Andrée; Trottier-Paquet, Myriam; Bêty, Joël; Lamarre, Vincent; Lecomte, Nicolas

2016-01-01

Predation is one of the main factors explaining nesting mortality in most bird species. Birds can avoid nest predation or reduce predation pressure by breeding at higher latitude, showing anti-predator behaviour, selecting nest sites protected from predators, and nesting in association with protective species. American Golden-Plovers (Pluvialis dominica) defend their territory by using various warning and distraction behaviours displayed at varying levels of intensity (hereafter "conspicuous behaviour"), as well as more aggressive behaviours such as aerial attacks, but only in some populations. Such antipredator behaviour has the potential to repel predators and thus benefit the neighbouring nests by decreasing their predation risk. Yet, conspicuous behaviour could also attract predators by signalling the presence of a nest. To test for the existence of a protective effect associated with the conspicuous antipredator behaviour of American Golden-Plovers, we studied the influence of proximity to plover nests on predation risk of artificial nests on Igloolik Island (Nunavut, Canada) in July 2014. We predicted that the predation risk of artificial nests would decrease with proximity to and density of plover nests. We monitored 18 plover nests and set 35 artificial nests at 30, 50, 100, 200, and 500 m from seven of those plover nests. We found that the predation risk of artificial nests increases with the density of active plover nests. We also found a significant negative effect of the distance to the nearest active protector nest on predation risk of artificial nests. Understanding how the composition and structure of shorebird communities generate spatial patterns in predation risks represents a key step to better understand the importance of these species of conservation concern in tundra food webs.

Nest site characteristics, nesting movements, and lack of long-term nest site fidelity in Agassiz's desert tortoises at a wind energy facility in southern California

USGS Publications Warehouse

Lovich, Jeffrey E.; Agha, Mickey; Yackulic, Charles B.; Meyer-Wilkins, Kathie; Bjurlin, Curtis; Ennen, Joshua R.; Arundel, Terry R.; Austin, Meaghan

2014-01-01

Nest site selection has important consequences for maternal and offspring survival and fitness. Females of some species return to the same nesting areas year after year. We studied nest site characteristics, fidelity, and daily pre-nesting movements in a population of Agassiz’s desert tortoises (Gopherus agassizii) at a wind energy facility in southern California during two field seasons separated by over a decade. No females returned to the same exact nest site within or between years but several nested in the same general area. However, distances between first and second clutches within a year (2000) were not significantly different from distances between nests among years (2000 and 2011) for a small sample of females, suggesting some degree of fidelity within their normal activity areas. Environmental attributes of nest sites did not differ significantly among females but did among years due largely to changes in perennial plant structure as a result of multiple fires. Daily pre-nesting distances moved by females decreased consistently from the time shelled eggs were first visible in X-radiographs until oviposition, again suggesting some degree of nest site selection. Tortoises appear to select nest sites that are within their long-term activity areas, inside the climate-moderated confines of one of their self-constructed burrows, and specifically, at a depth in the burrow that minimizes exposure of eggs and embryos to lethal incubation temperatures. Nesting in “climate-controlled” burrows and nest guarding by females relaxes some of the constraints that drive nest site selection in other oviparous species.

Variation in the structure of bird nests between northern Manitoba and southeastern Ontario.

PubMed

Crossman, Carla A; Rohwer, Vanya G; Martin, Paul R

2011-04-28

Traits that converge in appearance under similar environmental conditions among phylogenetically independent lineages are thought to represent adaptations to local environments. We tested for convergence in nest morphology and composition of birds breeding in two ecologically different locations in Canada: Churchill in northern Manitoba and Elgin in southeastern Ontario. We examined nests from four families of passerine birds (Turdidae: Turdus, Parulidae: Dendroica, Emberizidae: Passerculus and Fringillidae: Carduelis) where closely related populations or species breed in both locations. Nests of American Robins, Yellow Warblers, and Carduelis finches had heavier nest masses, and tended to have thicker nest-walls, in northern Manitoba compared with conspecifics or congenerics breeding in southeastern Ontario. Together, all species showed evidence for wider internal and external nest-cup diameters in northern Manitoba, while individual species showed varying patterns for internal nest-cup and external nest depths. American Robins, Yellow Warblers, and Carduelis finches in northern Manitoba achieved heavier nest masses in different ways. American Robins increased all materials in similar proportions, and Yellow Warblers and Common Redpolls used greater amounts of select materials. While changes in nest composition vary uniquely for each species, the pattern of larger nests in northern Manitoba compared to southeastern Ontario in three of our four phylogenetically-independent comparisons suggests that birds are adapting to similar selective pressures between locations.

Variation in clutch size in relation to nest size in birds

PubMed Central

Møller, Anders P; Adriaensen, Frank; Artemyev, Alexandr; Bańbura, Jerzy; Barba, Emilio; Biard, Clotilde; Blondel, Jacques; Bouslama, Zihad; Bouvier, Jean-Charles; Camprodon, Jordi; Cecere, Francesco; Charmantier, Anne; Charter, Motti; Cichoń, Mariusz; Cusimano, Camillo; Czeszczewik, Dorota; Demeyrier, Virginie; Doligez, Blandine; Doutrelant, Claire; Dubiec, Anna; Eens, Marcel; Eeva, Tapio; Faivre, Bruno; Ferns, Peter N; Forsman, Jukka T; García-Del-Rey, Eduardo; Goldshtein, Aya; Goodenough, Anne E; Gosler, Andrew G; Góźdź, Iga; Grégoire, Arnaud; Gustafsson, Lars; Hartley, Ian R; Heeb, Philipp; Hinsley, Shelley A; Isenmann, Paul; Jacob, Staffan; Järvinen, Antero; Juškaitis, Rimvydas; Korpimäki, Erkki; Krams, Indrikis; Laaksonen, Toni; Leclercq, Bernard; Lehikoinen, Esa; Loukola, Olli; Lundberg, Arne; Mainwaring, Mark C; Mänd, Raivo; Massa, Bruno; Mazgajski, Tomasz D; Merino, Santiago; Mitrus, Cezary; Mönkkönen, Mikko; Morales-Fernaz, Judith; Morin, Xavier; Nager, Ruedi G; Nilsson, Jan-Åke; Nilsson, Sven G; Norte, Ana C; Orell, Markku; Perret, Philippe; Pimentel, Carla S; Pinxten, Rianne; Priedniece, Ilze; Quidoz, Marie-Claude; Remeš, Vladimir; Richner, Heinz; Robles, Hugo; Rytkönen, Seppo; Senar, Juan Carlos; Seppänen, Janne T; da Silva, Luís P; Slagsvold, Tore; Solonen, Tapio; Sorace, Alberto; Stenning, Martyn J; Török, János; Tryjanowski, Piotr; van Noordwijk, Arie J; von Numers, Mikael; Walankiewicz, Wiesław; Lambrechts, Marcel M

2014-01-01

Nests are structures built to support and protect eggs and/or offspring from predators, parasites, and adverse weather conditions. Nests are mainly constructed prior to egg laying, meaning that parent birds must make decisions about nest site choice and nest building behavior before the start of egg-laying. Parent birds should be selected to choose nest sites and to build optimally sized nests, yet our current understanding of clutch size-nest size relationships is limited to small-scale studies performed over short time periods. Here, we quantified the relationship between clutch size and nest size, using an exhaustive database of 116 slope estimates based on 17,472 nests of 21 species of hole and non-hole-nesting birds. There was a significant, positive relationship between clutch size and the base area of the nest box or the nest, and this relationship did not differ significantly between open nesting and hole-nesting species. The slope of the relationship showed significant intraspecific and interspecific heterogeneity among four species of secondary hole-nesting species, but also among all 116 slope estimates. The estimated relationship between clutch size and nest box base area in study sites with more than a single size of nest box was not significantly different from the relationship using studies with only a single size of nest box. The slope of the relationship between clutch size and nest base area in different species of birds was significantly negatively related to minimum base area, and less so to maximum base area in a given study. These findings are consistent with the hypothesis that bird species have a general reaction norm reflecting the relationship between nest size and clutch size. Further, they suggest that scientists may influence the clutch size decisions of hole-nesting birds through the provisioning of nest boxes of varying sizes. PMID:25478150

Variation in clutch size in relation to nest size in birds.

PubMed

Møller, Anders P; Adriaensen, Frank; Artemyev, Alexandr; Bańbura, Jerzy; Barba, Emilio; Biard, Clotilde; Blondel, Jacques; Bouslama, Zihad; Bouvier, Jean-Charles; Camprodon, Jordi; Cecere, Francesco; Charmantier, Anne; Charter, Motti; Cichoń, Mariusz; Cusimano, Camillo; Czeszczewik, Dorota; Demeyrier, Virginie; Doligez, Blandine; Doutrelant, Claire; Dubiec, Anna; Eens, Marcel; Eeva, Tapio; Faivre, Bruno; Ferns, Peter N; Forsman, Jukka T; García-Del-Rey, Eduardo; Goldshtein, Aya; Goodenough, Anne E; Gosler, Andrew G; Góźdź, Iga; Grégoire, Arnaud; Gustafsson, Lars; Hartley, Ian R; Heeb, Philipp; Hinsley, Shelley A; Isenmann, Paul; Jacob, Staffan; Järvinen, Antero; Juškaitis, Rimvydas; Korpimäki, Erkki; Krams, Indrikis; Laaksonen, Toni; Leclercq, Bernard; Lehikoinen, Esa; Loukola, Olli; Lundberg, Arne; Mainwaring, Mark C; Mänd, Raivo; Massa, Bruno; Mazgajski, Tomasz D; Merino, Santiago; Mitrus, Cezary; Mönkkönen, Mikko; Morales-Fernaz, Judith; Morin, Xavier; Nager, Ruedi G; Nilsson, Jan-Åke; Nilsson, Sven G; Norte, Ana C; Orell, Markku; Perret, Philippe; Pimentel, Carla S; Pinxten, Rianne; Priedniece, Ilze; Quidoz, Marie-Claude; Remeš, Vladimir; Richner, Heinz; Robles, Hugo; Rytkönen, Seppo; Senar, Juan Carlos; Seppänen, Janne T; da Silva, Luís P; Slagsvold, Tore; Solonen, Tapio; Sorace, Alberto; Stenning, Martyn J; Török, János; Tryjanowski, Piotr; van Noordwijk, Arie J; von Numers, Mikael; Walankiewicz, Wiesław; Lambrechts, Marcel M

2014-09-01

Nests are structures built to support and protect eggs and/or offspring from predators, parasites, and adverse weather conditions. Nests are mainly constructed prior to egg laying, meaning that parent birds must make decisions about nest site choice and nest building behavior before the start of egg-laying. Parent birds should be selected to choose nest sites and to build optimally sized nests, yet our current understanding of clutch size-nest size relationships is limited to small-scale studies performed over short time periods. Here, we quantified the relationship between clutch size and nest size, using an exhaustive database of 116 slope estimates based on 17,472 nests of 21 species of hole and non-hole-nesting birds. There was a significant, positive relationship between clutch size and the base area of the nest box or the nest, and this relationship did not differ significantly between open nesting and hole-nesting species. The slope of the relationship showed significant intraspecific and interspecific heterogeneity among four species of secondary hole-nesting species, but also among all 116 slope estimates. The estimated relationship between clutch size and nest box base area in study sites with more than a single size of nest box was not significantly different from the relationship using studies with only a single size of nest box. The slope of the relationship between clutch size and nest base area in different species of birds was significantly negatively related to minimum base area, and less so to maximum base area in a given study. These findings are consistent with the hypothesis that bird species have a general reaction norm reflecting the relationship between nest size and clutch size. Further, they suggest that scientists may influence the clutch size decisions of hole-nesting birds through the provisioning of nest boxes of varying sizes.

Do common eiders nest in kin groups? Microgeographic genetic structure in a philopatric sea duck

USGS Publications Warehouse

Sonsthagen, S.A.; Talbot, S.L.; Lanctot, Richard B.; McCracken, K.G.

2010-01-01

We investigated local genetic associations among female Pacific common eiders (Somateria mollissima v-nigrum) nesting in a stochastic Arctic environment within two groups of barrier islands (Simpson Lagoon and Mikkelsen Bay) in the Beaufort Sea, Alaska. Nonrandom genetic associations were observed among nesting females using regional spatial autocorrelation analyses for distance classes up to 1000 m in Simpson Lagoon. Nearest-neighbour analyses identified clusters of genetically related females with positive lr values observed for 0-13% and 0-7% of the comparisons in Simpson Lagoon and Mikkelsen Bay, respectively, across years. These results indicate that a proportion of females are nesting in close proximity to more genetically related individuals, albeit at low frequency. Such kin groupings may form through active association between relatives or through natal philopatry and breeding site fidelity. Eiders nest in close association with driftwood, which is redistributed annually by seasonal storms. Yet, genetic associations were still observed. Microgeographic structure may thus be more attributable to kin association than natal philopatry and site fidelity. However, habitat availability may also influence the level of structure observed. Regional structure was present only within Simpson Lagoon and this island group includes at least three islands with sufficient driftwood for colonies, whereas only one island at Mikkelsen Bay has these features. A long-term demographic study is needed to understand more fully the mechanisms that lead to fine-scale genetic structure observed in common eiders breeding in the Beaufort Sea. ?? Published 2010. This article is a US Government work and is in the public domain in the USA.

A multivariate multilevel Gaussian model with a mixed effects structure in the mean and covariance part.

PubMed

Li, Baoyue; Bruyneel, Luk; Lesaffre, Emmanuel

2014-05-20

A traditional Gaussian hierarchical model assumes a nested multilevel structure for the mean and a constant variance at each level. We propose a Bayesian multivariate multilevel factor model that assumes a multilevel structure for both the mean and the covariance matrix. That is, in addition to a multilevel structure for the mean we also assume that the covariance matrix depends on covariates and random effects. This allows to explore whether the covariance structure depends on the values of the higher levels and as such models heterogeneity in the variances and correlation structure of the multivariate outcome across the higher level values. The approach is applied to the three-dimensional vector of burnout measurements collected on nurses in a large European study to answer the research question whether the covariance matrix of the outcomes depends on recorded system-level features in the organization of nursing care, but also on not-recorded factors that vary with countries, hospitals, and nursing units. Simulations illustrate the performance of our modeling approach. Copyright © 2013 John Wiley & Sons, Ltd.

Environmental change mediates mate choice for an extended phenotype, but not for mate quality.

PubMed

Head, Megan L; Fox, Rebecca J; Barber, Iain

2017-01-01

Sexual cues, including extended phenotypes, are expected to be reliable indicators of male genetic quality and/or provide information on parental quality. However, the reliability of these cues may be dependent on stability of the environment, with heterogeneity affecting how selection acts on such traits. Here, we test how environmental change mediates mate choice for multiple sexual traits, including an extended phenotype--the structure of male-built nests - in stickleback fish. First, we manipulated the dissolved oxygen (DO) content of water to create high or low DO environments in which male fish built nests. Then we recorded the mate choice of females encountering these males (and their nests), under either the same or reversed DO conditions. Males in high DO environments built more compact nests than those in low DO conditions and males adjusted their nest structure in response to changing conditions. Female mate choice for extended phenotype (male nests) was environmentally dependent (females chose more compact nests in high DO conditions), while female choice for male phenotype was not (females chose large, vigorous males regardless of DO level). Examining mate choice in this dynamic context suggests that females evaluate the reliability of multiple sexual cues, taking into account environmental heterogeneity. © 2016 The Author(s). Evolution published by Wiley Periodicals, Inc. on behalf of The Society for the Study of Evolution.

Are there optimal densities for prairie birds?

USGS Publications Warehouse

Skagen, S.K.; Adams, A.A.Y.

2010-01-01

The major forces of food and predation shape fitness-enhancing decisions of birds at all stages of their life cycles. During the breeding season, birds can minimize nest loss due to predation by selecting sites with a lower probability of predation. To understand the environmental and social aspects and consequences of breedingsite selection in prairie birds, we explored variation in nest-survival patterns of the Lark Bunting (Calamospiza melanocorys) in the shortgrass prairie region of North America. Over four breeding seasons, we documented the survival of 405 nests, conducted 60 surveys to estimate bird densities, and measured several vegetative features to describe habitat structure in 24 randomly selected study plots. Nest survival varied with the buntings' density as described by a quadratic polynomial, increasing with density below 1.5 birds ha-1 and decreasing with density between 1.5 and 3 birds ha-1, suggesting that an optimal range of densities favors reproductive success of the Lark Bunting, which nests semi-colonially. Nest survival also increased with increasing vegetation structure of study plots and varied with age of the nest, increasing during early incubation and late in the nestling stage and declining slightly from mid-incubation to the middle of the nestling period. The existence of an optimal range of densities in this semi-colonial species can be elucidated by the "commodity-selection hypothesis" at low densities and density dependence at high densities. ?? The Cooper Ornithological Society 2010.

Percolation in insect nest networks: Evidence for optimal wiring

NASA Astrophysics Data System (ADS)

Valverde, Sergi; Corominas-Murtra, Bernat; Perna, Andrea; Kuntz, Pascale; Theraulaz, Guy; Solé, Ricard V.

2009-06-01

Optimization has been shown to be a driving force for the evolution of some biological structures, such as neural maps in the brain or transport networks. Here we show that insect networks also display characteristic traits of optimality. By using a graph representation of the chamber organization of termite nests and a disordered lattice model, it is found that these spatial nests are close to a percolation threshold. This suggests that termites build efficient systems of galleries spanning most of the nest volume at low cost. The evolutionary consequences are outlined.

Optimal Design in Three-Level Block Randomized Designs with Two Levels of Nesting: An ANOVA Framework with Random Effects

ERIC Educational Resources Information Center

Konstantopoulos, Spyros

2013-01-01

Large-scale experiments that involve nested structures may assign treatment conditions either to subgroups such as classrooms or to individuals such as students within subgroups. Key aspects of the design of such experiments include knowledge of the variance structure in higher levels and the sample sizes necessary to reach sufficient power to…

Multilevel multi-informant structure of the authoritative school climate survey.

PubMed

Konold, Timothy; Cornell, Dewey; Huang, Francis; Meyer, Patrick; Lacey, Anna; Nekvasil, Erin; Heilbrun, Anna; Shukla, Kathan

2014-09-01

The Authoritative School Climate Survey was designed to provide schools with a brief assessment of 2 key characteristics of school climate--disciplinary structure and student support--that are hypothesized to influence 2 important school climate outcomes--student engagement and prevalence of teasing and bullying in school. The factor structure of these 4 constructs was examined with exploratory and confirmatory factor analyses in a statewide sample of 39,364 students (Grades 7 and 8) attending 423 schools. Notably, the analyses used a multilevel structural approach to model the nesting of students in schools for purposes of evaluating factor structure, demonstrating convergent and concurrent validity and gauging the structural invariance of concurrent validity coefficients across gender. These findings provide schools with a core group of school climate measures guided by authoritative discipline theory. PsycINFO Database Record (c) 2014 APA, all rights reserved.

A tableau approach of the KSS nest

NASA Astrophysics Data System (ADS)

Peng, Wenjuan; Qiu, Weiyuan; Roesch, Pascale; Tan, Lei; Yin, Yongcheng

The KSS nest is a sophisticated choice of puzzle pieces given in [Ann. of Math. 165 (2007), 749-841]. This nest, once combined with the KL-Lemma, has proven to be a powerful machinery, leading to several important advancements in the field of holomorphic dynamics. We give here a presentation of the KSS nest in terms of tableau. This is an effective language invented by Branner and Hubbard to deal with the complexity of the dynamics of puzzle pieces. We show, in a typical situation, how to make the combination between the KSS nest and the KL-Lemma. One consequence of this is the recently proved Branner-Hubbard conjecture. Our estimates here can be used to give an alternative proof of the rigidity property.

The effect of predation on begging-call evolution in nestling wood warblers.

PubMed

Haskell

1999-04-01

I combined a comparative study of begging in ground- and tree-nesting wood warblers (Parulidae) with experimental measures of the predation costs of warbler begging calls. Throughout their development, ground-nesting warbler nestlings had significantly higher-frequency begging calls than did tree-nesting warblers. There was also a trend for ground-nesting birds to have less rapidly modulated calls. There were no consistent associations between nesting site and the amplitude of the calls. Using miniature walkie-talkies hidden inside artificial nests, I reciprocally transplanted the begging calls of 5- and 8-day-old black-throated blue warblers, Dendroica caerulescens (tree-nesting) and ovenbirds, Seiurus aurocapillus (ground-nesting) and measured the corresponding changes in rates of nest predation. For the begging calls of 8-day-old nestlings, but not those of 5-day-olds, the calls of the tree-nesting species coming from ground nests incurred greater costs than did the calls of ground nesters. The reciprocal transplant had little effect on the rate of predation. Tooth imprints on clay eggs placed in artificial nests indicated that eastern chipmunks, Tamias striatus, were responsible for the increased cost of begging for black-throated blue calls coming from the ground. These data suggest that nest predation may be responsible for maintaining some of the interspecific differences in the acoustic structure of begging calls. Copyright 1999 The Association for the Study of Animal Behaviour.

Nest survival of American Coots relative to grazing, burning, and water depths

USGS Publications Warehouse

Austin, Jane E.; Buhl, Deborah A.

2011-01-01

Water and emergent vegetation are key features influencing nest site selection and success for many marsh-nesting waterbirds. Wetland management practices such as grazing, burning, and water-level manipulations directly affect these features and can influence nest survival. We used model selection and before-after-control-impact approaches to evaluate the effects of water depth and four common land-management practices or treatments, i.e., summer grazing, fall grazing, fall burning, and idle (no active treatment) on nest survival of American coots (Fulica americana) nesting at Grays Lake, a large montane wetland in southeast Idaho. The best model included the variables year × treatment, and quadratic functions of date, water depth, and nest age; height of vegetation at the nest did not improve the best model. However, results from the before-after-control-impact analysis indicate that management practices affected nest success via vegetation and involved interactions of hydrology, residual vegetation, and habitat composition. Nest success in idled fields changed little between pre- and post-treatment periods, whereas nest success declined in fields that were grazed or burned, with the most dramatic declines the year following treatments. The importance of water depth may be amplified in this wetland system because of rapid water-level withdrawal during the nesting season. Water and land-use values for area ranchers, management for nesting waterbirds, and long-term wetland function are important considerations in management of water levels and vegetation.

The nest growth of the neotropical mound-building termite, Cornitermes cumulans: a micromorphological analysis.

PubMed

Cosarinsky, Marcela I

2011-01-01

The nests of Cornitermes cumulans K. (Isoptera: Termitidae), a very common termite in South American grasslands, display notable morphological transformations during the development of the colony. Young colonies inhabit small subterranean nests that develop into large, conspicuous, epigean mounds, inhabited by very populous colonies. Those macromorphological transformations are accompanied by micromorphological changes occurring gradually in the nest walls. The micromorphological changes during nest development described in the present study expand on previous macromorphological descriptions by explaining the re-organization of the soil components during nest growth. In subterranean nests, walls are composed of piles of lensshaped aggregates of soil material, each one surrounded by a thin organic coating. As the nest grows, mound walls are constructed by disassembling this first lenticular structure and rearranging the materials in a new fabric, where sand grains are loosely distributed among soil microaggregates of organic matter and clay. This is also a temporary construction, because the walls of large nests are composed of a porous mass of sands densely cemented with organic matter and clay in the mound, and a compact mass of the same components in the floor.

Multiple chiral topological states in liquid crystals from unstructured light beams

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

Loussert, Charles; Brasselet, Etienne, E-mail: e.brasselet@loma.u-bordeaux1.fr

2014-02-03

It is shown experimentally that unstructured light beams can generate a wealth of distinct metastable defect structures in thin films of chiral liquid crystals. Various kinds of individual chiral topological states are obtained as well as dimers and trimers, which correspond to the entanglement of several topological unit cells. Self-assembled nested assemblies of several metastable particle-like topological states can also be formed. Finally, we propose and experimentally demonstrate an opto-electrical approach to generate tailor-made architectures.

Nest design in a changing world: great tit Parus major nests from a Mediterranean city environment as a case study.

PubMed

Lambrechts, Marcel M; Charmantier, Anne; Demeyrier, Virginie; Lucas, Annick; Perret, Samuel; Abouladzé, Matthieu; Bonnet, Michel; Canonne, Coline; Faucon, Virginie; Grosset, Stéphanie; le Prado, Gaëlle; Lidon, Frédéric; Noell, Thierry; Pagano, Pascal; Perret, Vincent; Pouplard, Stéphane; Spitaliéry, Rémy; Bernard, Cyril; Perret, Philippe; Blondel, Jacques; Grégoire, Arnaud

2017-12-01

Investigations of urbanization effects on birds have focused mainly on breeding traits expressed after the nest-building stage (e.g. first-egg date, clutch size, breeding success, and offspring characteristics). Urban studies largely ignored how and why the aspects of nest building might be associated with the degree of urbanization. As urban environments are expected to present novel environmental changes relative to rural environments, it is important to evaluate how nest-building behavior is impacted by vegetation modifications associated with urbanization. To examine nest design in a Mediterranean city environment, we allowed urban great tits ( Parus major ) to breed in nest boxes in areas that differed in local vegetation cover. We found that different measures of nest size or mass were not associated with vegetation cover. In particular, nests located adjacent to streets with lower vegetation cover were not smaller or lighter than nests in parks with higher vegetation cover. Nests adjacent to streets contained more pine needles than nests in parks. In addition, in nests adjacent to streets, nests from boxes attached to pine trees contained more pine needles than nests from boxes attached to other trees. We suggest that urban-related alterations in vegetation cover do not directly impose physical limits on nest size in species that are opportunistic in the selection of nesting material. However, nest composition as reflected in the use of pine needles was clearly affected by habitat type and the planted tree species present, which implies that rapid habitat change impacts nest composition. We do not exclude that urbanization might impact other aspects of nest building behaviour not covered in our study (e.g. costs of searching for nest material), and that the strengths of the associations between urbanization and nest structures might differ among study populations or species.

Waiting for trees to grow: nest survival, brood parasitism, and the impact of reforestation efforts

USGS Publications Warehouse

Hazler, K.R.; Twedt, D.J.; Cooper, R.J.

2005-01-01

Of the forested wetlands that once covered the Mississippi Alluvial Valley, only -25% remain due to large-scale conversion to agriculture. Reforestation efforts are currently underway, but tracts planted with slow-growing oaks maintain the structure of a grassland for 5 yr or longer, and will require at least 40 yr to resemble a mature forest. Nonetheless, it is hoped that reforestation, even in early stages, can effectively increase core area in extant tracts of mature forest by reducing higher rates of nest failure and brood parasitism often associated with forest-agriculture interfaces. To test this, we monitored nests of a mature-forest specialist, the Acadian Flycatcher, in extensive bottomland forests adjacent to agricultural fields and reforested tracts (<20 yr-old). We used an information-theoretic approach to evaluate alternative hypotheses regarding the relative impacts of agriculture and reforestation in the landscape. Controlling for year, season, and stand basal area, there was little evidence that landscape context significantly affected nest survival, although survival tended to increase with decreasing amounts of agriculture. The probability of brood parasitism increased with greater proportions of open habitats in the landscape. There was much stronger support for the hypothesis that parasitism rates depended on the sum of agricultural and reforested tracts, rather than on the amount of agriculture alone. Thus, reforested tracts are not expected to have the desired effect of reducing parasitism rates in the adjacent mature forest until several decades have passed.

Optimization for minimum sensitivity to uncertain parameters

NASA Technical Reports Server (NTRS)

Pritchard, Jocelyn I.; Adelman, Howard M.; Sobieszczanski-Sobieski, Jaroslaw

1994-01-01

A procedure to design a structure for minimum sensitivity to uncertainties in problem parameters is described. The approach is to minimize directly the sensitivity derivatives of the optimum design with respect to fixed design parameters using a nested optimization procedure. The procedure is demonstrated for the design of a bimetallic beam for minimum weight with insensitivity to uncertainties in structural properties. The beam is modeled with finite elements based on two dimensional beam analysis. A sequential quadratic programming procedure used as the optimizer supplies the Lagrange multipliers that are used to calculate the optimum sensitivity derivatives. The method was perceived to be successful from comparisons of the optimization results with parametric studies.

Is the nestedness of metazoan parasite assemblages of marine fishes from the southeastern Pacific coast a pattern associated with the geographical distributional range of the host?

PubMed

González, M T; Oliva, M E

2009-04-01

Nested structure is a pattern originally described in island biogeography to characterize how a set of species is distributed among a set of islands. In parasite communities, nestedness has been intensively studied among individual fish from a locality. However, nested patterns among parasite assemblages from different host populations (localities) have scarcely been investigated. We recorded the occurrence of parasites in 9 fish species widely distributed along the southeastern Pacific coast to determine whether the ecto- and endoparasite assemblages of marine fishes show a nested structure associated with host distributional range. Nestedness was tested using Brualdi-Sanderson index of discrepancy (BR); and 5 null models incorporated in a 'Nestedness' programme (Ulrich, 2006). The ecto- and endoparasite richness do not show similar patterns of latitudinal gradients among fish hosts, with 33-66% of analysed ectoparasite assemblages, and 25-75% of endoparasite assemblages showing nested structures through the host distributional range. For ectoparasites, species richness gradients and nested structure (when present) might be associated with decreased host densities or could reflect negative environmental conditions in the distributional border of the host species, whereas for endoparasites might be caused by geographical breaks of prey or changes in prey availability (intermediate hosts). The sampled extension of the distributional range of the host species, as well as the lack of specificity of some parasites, could influence the detection of nestedness.

Advanced techniques for modeling avian nest survival

USGS Publications Warehouse

Dinsmore, S.J.; White, Gary C.; Knopf, F.L.

2002-01-01

Estimation of avian nest survival has traditionally involved simple measures of apparent nest survival or Mayfield constant-nest-survival models. However, these methods do not allow researchers to build models that rigorously assess the importance of a wide range of biological factors that affect nest survival. Models that incorporate greater detail, such as temporal variation in nest survival and covariates representative of individual nests represent a substantial improvement over traditional estimation methods. In an attempt to improve nest survival estimation procedures, we introduce the nest survival model now available in the program MARK and demonstrate its use on a nesting study of Mountain Plovers (Charadrius montanus Townsend) in Montana, USA. We modeled the daily survival of Mountain Plover nests as a function of the sex of the incubating adult, nest age, year, linear and quadratic time trends, and two weather covariates (maximum daily temperature and daily precipitation) during a six-year study (1995–2000). We found no evidence for yearly differences or an effect of maximum daily temperature on the daily nest survival of Mountain Plovers. Survival rates of nests tended by female and male plovers differed (female rate = 0.33; male rate = 0.49). The estimate of the additive effect for males on nest survival rate was 0.37 (95% confidence limits were 0.03, 0.71) on a logit scale. Daily survival rates of nests increased with nest age; the estimate of daily nest-age change in survival in the best model was 0.06 (95% confidence limits were 0.04, 0.09) on a logit scale. Daily precipitation decreased the probability that the nest would survive to the next day; the estimate of the additive effect of daily precipitation on the nest survival rate was −1.08 (95% confidence limits were −2.12, −0.13) on a logit scale. Our approach to modeling daily nest-survival rates allowed several biological factors of interest to be easily included in nest survival models and allowed us to generate more biologically meaningful estimates of nest survival.

A multiscale analysis of nest predation on Least Bell's Vireos (Vireo bellii pusillus)

USGS Publications Warehouse

Kus, Barbara E.; Peterson, Bonnie L.; Deutschman, Douglas H.

2008-01-01

We examined variables influencing nest predation on the endangered Least Bell's Vireo (Vireo bellii pusillus) at three spatial scales to determine what nest-site, habitat, or landscape characteristics affect the likelihood of nest predation and to determine the spatial distribution of predation risk and the variables influencing it. We used MARK to calculate daily survival rates of Least Bell's Vireo nests and applied an information-theoretic approach to evaluate support for logistic regression models of the effect of habitat variables on predation risk. Analysis of data for 195 nests collected during 1999 and 2000 at the San Luis Rey River and Pilgrim Creek in southern California revealed no effect of fine-scale factors, including nest height, supporting plant species, and three measures of nest concealment, on the likelihood of predation. At the intermediate scale, distances to the riparian-habitat edge and to internal gaps in the canopy were unrelated to nest survival. Surrounding land-use type was a poor predictor of predation risk, with the exception of proximity to golf course–park habitat and wetland. Nests within 400 m of golf course–park were only 20% as likely to avoid predation as nests >400 m from this habitat, and nests near wetland were more than twice as likely to survive as nests distant from wetland. Spatially, predation appeared to be random throughout the site, with localized clustering evident in the vicinity of golf course–park and wetland. Our results suggest that the landscape may be the most appropriate scale at which to manage nest predation in this system.

Reproductive Performance of a Declining Forest Passerine in Relation to Environmental and Social Factors: Implications for Species Conservation

PubMed Central

Grendelmeier, Alex; Arlettaz, Raphaël; Gerber, Michael; Pasinelli, Gilberto

2015-01-01

Identifying factors influencing a species' ecological niche and demography is a prerequisite for species conservation. However, our understanding of the interplay between demographic rates and biotic/abiotic factors is still poor for most species of conservation concern. We evaluated relevance of eight hypotheses relating to timing of breeding, temporal nest exposure, nest concealment, topography, tree structure, predation risk and disturbance, density dependence and weather for explaining variation in reproductive performance of the declining wood warbler Phylloscopus sibilatrix in northern Switzerland. Reproductive performance was monitored with cameras at 136 nests from 2010 to 2012 and was associated to temporal exposure, timing of breeding and concealment of nests. Daily nest survival was positively related to the number of grass and sedge tussocks, nest concealment and nest age. Clutch size and number of fledglings decreased, the later in the season a nest was initiated. Nest survival over an average nesting period of 31 days was 46.9 ± 0.07% (mean ± SE), daily nest survival rate was 0.976 ± 0.002. As for many ground-breeding birds, nest predation was the principal cause of nest failure, accounting for 79% of all nest losses. Conservation measures should aim at increasing the area of relatively homogenous forest stands featuring suitable habitats characterized by abundant and accessible grass and sedge tussocks. In managed forests, such conditions can be found in stands of middle age (i.e. pole wood) with little to no shrub layer. PMID:26172954

Reproductive Performance of a Declining Forest Passerine in Relation to Environmental and Social Factors: Implications for Species Conservation.

PubMed

Grendelmeier, Alex; Arlettaz, Raphaël; Gerber, Michael; Pasinelli, Gilberto

2015-01-01

Identifying factors influencing a species' ecological niche and demography is a prerequisite for species conservation. However, our understanding of the interplay between demographic rates and biotic/abiotic factors is still poor for most species of conservation concern. We evaluated relevance of eight hypotheses relating to timing of breeding, temporal nest exposure, nest concealment, topography, tree structure, predation risk and disturbance, density dependence and weather for explaining variation in reproductive performance of the declining wood warbler Phylloscopus sibilatrix in northern Switzerland. Reproductive performance was monitored with cameras at 136 nests from 2010 to 2012 and was associated to temporal exposure, timing of breeding and concealment of nests. Daily nest survival was positively related to the number of grass and sedge tussocks, nest concealment and nest age. Clutch size and number of fledglings decreased, the later in the season a nest was initiated. Nest survival over an average nesting period of 31 days was 46.9 ± 0.07% (mean ± SE), daily nest survival rate was 0.976 ± 0.002. As for many ground-breeding birds, nest predation was the principal cause of nest failure, accounting for 79% of all nest losses. Conservation measures should aim at increasing the area of relatively homogenous forest stands featuring suitable habitats characterized by abundant and accessible grass and sedge tussocks. In managed forests, such conditions can be found in stands of middle age (i.e. pole wood) with little to no shrub layer.

Model-free learning on robot kinematic chains using a nested multi-agent topology

NASA Astrophysics Data System (ADS)

Karigiannis, John N.; Tzafestas, Costas S.

2016-11-01

This paper proposes a model-free learning scheme for the developmental acquisition of robot kinematic control and dexterous manipulation skills. The approach is based on a nested-hierarchical multi-agent architecture that intuitively encapsulates the topology of robot kinematic chains, where the activity of each independent degree-of-freedom (DOF) is finally mapped onto a distinct agent. Each one of those agents progressively evolves a local kinematic control strategy in a game-theoretic sense, that is, based on a partial (local) view of the whole system topology, which is incrementally updated through a recursive communication process according to the nested-hierarchical topology. Learning is thus approached not through demonstration and training but through an autonomous self-exploration process. A fuzzy reinforcement learning scheme is employed within each agent to enable efficient exploration in a continuous state-action domain. This paper constitutes in fact a proof of concept, demonstrating that global dexterous manipulation skills can indeed evolve through such a distributed iterative learning of local agent sensorimotor mappings. The main motivation behind the development of such an incremental multi-agent topology is to enhance system modularity, to facilitate extensibility to more complex problem domains and to improve robustness with respect to structural variations including unpredictable internal failures. These attributes of the proposed system are assessed in this paper through numerical experiments in different robot manipulation task scenarios, involving both single and multi-robot kinematic chains. The generalisation capacity of the learning scheme is experimentally assessed and robustness properties of the multi-agent system are also evaluated with respect to unpredictable variations in the kinematic topology. Furthermore, these numerical experiments demonstrate the scalability properties of the proposed nested-hierarchical architecture, where new agents can be recursively added in the hierarchy to encapsulate individual active DOFs. The results presented in this paper demonstrate the feasibility of such a distributed multi-agent control framework, showing that the solutions which emerge are plausible and near-optimal. Numerical efficiency and computational cost issues are also discussed.

Embolectomy of a Bird's Nest Vena Caval Filter.

PubMed

Chitwood, W R; Chiang, K S; Williams, J M; Zeri, R S; Semer, D A

1994-12-01

In this case report we describe a successful embolectomy of a partially migrated Bird's Nest Caval Filter with attached embolic material. We used transesophageal echocardiography to guide the surgical approach. The patient recovered uneventfully from both the embolectomy and the subsequent pelvic operation.

[Application of nested case-control study on safe evaluation of post-marketing traditional Chinese medicine injection].

PubMed

Xiao, Ying; Zhao, Yubin; Xie, Yanming

2011-10-01

The nested case-control study design (or the case-control in a cohort study) is described here as a new study design used in safe evaluation of post-marketing traditional Chinese medicine injection. In the nested case-control study, cases of a disease that occur in a defined cohort are identified and, for each, a specified number of matched controls is selected from among those in the cohort who have not developed the disease by the time of disease occurrence in the case. For many research questions, the nested case-control design potentially offers impressive reductions in costs and efforts of data collection and analysis compared with the full cohort approach, with relatively minor loss in statistical efficiency. The nested case-control design is particularly advantageous for studies in safe evaluation of post-marketing traditional Chinese medicine injection. Some examples of the application of nested case-control study were given.

FVCOM one-way and two-way nesting using ESMF: Development and validation

NASA Astrophysics Data System (ADS)

Qi, Jianhua; Chen, Changsheng; Beardsley, Robert C.

2018-04-01

Built on the Earth System Modeling Framework (ESMF), the one-way and two-way nesting methods were implemented into the unstructured-grid Finite-Volume Community Ocean Model (FVCOM). These methods help utilize the unstructured-grid multi-domain nesting of FVCOM with an aim at resolving the multi-scale physical and ecosystem processes. A detail of procedures on implementing FVCOM into ESMF was described. The experiments were made to validate and evaluate the performance of the nested-grid FVCOM system. The first was made for a wave-current interaction case with a two-domain nesting with an emphasis on qualifying a critical need of nesting to resolve a high-resolution feature near the coast and harbor with little loss in computational efficiency. The second was conducted for the pseudo river plume cases to examine the differences in the model-simulated salinity between one-way and two-way nesting approaches and evaluate the performance of mass conservative two-way nesting method. The third was carried out for the river plume case in the realistic geometric domain in Mass Bay, supporting the importance for having the two-way nesting for coastal-estuarine integrated modeling. The nesting method described in this paper has been used in the Northeast Coastal Ocean Forecast System (NECOFS)-a global-regional-coastal nesting FVCOM system that has been placed into the end-to-end forecast and hindcast operations since 2007.

Response of beach-nesting American Oystercatchers to off-road vehicles: An experimental approach reveals physiological nuances and decreased nest attendance

USGS Publications Warehouse

Felton, Shilo K.; Pollock, Kenneth H.; Simons, Theodore R.

2018-01-01

Shorebird populations face increasing challenges as rising sea levels and growing human populations constrain their breeding habitats. On recreational beaches, the nesting season often coincides with a season of high visitor use, increasing the potential for conflict, which may negatively influence beach-nesting shorebird species. We designed a field experiment to study the responses of nesting American Oystercatchers (Haematopus palliatus) to off-road passenger vehicles (ORVs) at Cape Hatteras and Cape Lookout National Seashores in North Carolina, USA. We used continuous video and heart rate recordings to assess changes in the behavior and physiology of incubating oystercatchers. We conducted driving experiments affecting 7 nesting pairs in 2014 and 19 nesting pairs in 2015, between April and July of each year. Experimental treatments were repeated throughout the incubation period for each nest. Although responses were highly variable within and among pairs, paired randomized permutation tests indicated that, overall, oystercatcher pairs spent a greater proportion of time with their heads up and exhibited slower heart rates during driving treatments. Pairs also left their nests more frequently and attended their nests for a lower proportion of time during driving treatments, although these responses diminished over time. Higher nest attendance and lower departure rates late in incubation may have reflected a stronger attachment to nests closer to hatching or habituation to the driving treatment, although individuals continued to exhibit physiological responses to passing vehicles throughout incubation. Beach-nesting birds may benefit from reduced vehicle traffic at their nesting sites, allowing parents to spend more time attending the nest and less time on defensive behaviors.

The dependability of medical students' performance ratings as documented on in-training evaluations.

PubMed

van Barneveld, Christina

2005-03-01

To demonstrate an approach to obtain an unbiased estimate of the dependability of students' performance ratings during training, when the data-collection design includes nesting of student in rater, unbalanced nest sizes, and dependent observations. In 2003, two variance components analyses of in-training evaluation (ITE) report data were conducted using urGENOVA software. In the first analysis, the dependability for the nested and unbalanced data-collection design was calculated. In the second analysis, an approach using multiple generalizability studies was used to obtain an unbiased estimate of the student variance component, resulting in an unbiased estimate of dependability. Results suggested that there is bias in estimates of the dependability of students' performance on ITEs that are attributable to the data-collection design. When the bias was corrected, the results indicated that the dependability of ratings of student performance was almost zero. The combination of the multiple generalizability studies method and the use of specialized software provides an unbiased estimate of the dependability of ratings of student performance on ITE scores for data-collection designs that include nesting of student in rater, unbalanced nest sizes, and dependent observations.

Nesting biology of Black-shouldered Kite (Elanus caeruleus) in oil palm landscape in Carey Island, Peninsular Malaysia.

PubMed

Ramli, Rosli; Fauzi, Aimi

2018-03-01

Black-shouldered Kite ( Elanus caeruleus ) is a well-known raptor that inhabits open areas such as oil palm plantation or paddy field. To determine preferable habitat and nesting site of Black-shouldered Kite in oil palm landscape, we conducted a study on Black-shouldered Kite's nesting biology in Carey Island, Selangor, Malaysia. We divided the island into six types of habitat and conducted road-side count of Black-shouldered Kite from April 2009 to February 2011. Whenever the Black-shouldered Kite was detected, we thoroughly searched the surrounding area for their nest. In total, we have recorded forty nests. The nests were built on 15 species of trees but most of the trees shared common physical characteristics. Some novice breeders also used oil palm tree as their nesting site. Structure and building materials of nests constructed on oil palm trees were different from nests built on other trees. Of all breeding attempts, only four nests which were located in residential area adjacent to young oil palm habitat were successful. Among important characteristics of successful nesting site include taller trees with strong branches and good leaf coverage. These trees not only protect nests from predator detection (except from other predatory birds) and physical environment but also facilitate Black-shouldered Kite's foraging activities by providing good vantage point.

Variation in the Structure of Bird Nests between Northern Manitoba and Southeastern Ontario

PubMed Central

Crossman, Carla A.; Rohwer, Vanya G.; Martin, Paul R.

2011-01-01

Traits that converge in appearance under similar environmental conditions among phylogenetically independent lineages are thought to represent adaptations to local environments. We tested for convergence in nest morphology and composition of birds breeding in two ecologically different locations in Canada: Churchill in northern Manitoba and Elgin in southeastern Ontario. We examined nests from four families of passerine birds (Turdidae: Turdus, Parulidae: Dendroica, Emberizidae: Passerculus and Fringillidae: Carduelis) where closely related populations or species breed in both locations. Nests of American Robins, Yellow Warblers, and Carduelis finches had heavier nest masses, and tended to have thicker nest-walls, in northern Manitoba compared with conspecifics or congenerics breeding in southeastern Ontario. Together, all species showed evidence for wider internal and external nest-cup diameters in northern Manitoba, while individual species showed varying patterns for internal nest-cup and external nest depths. American Robins, Yellow Warblers, and Carduelis finches in northern Manitoba achieved heavier nest masses in different ways. American Robins increased all materials in similar proportions, and Yellow Warblers and Common Redpolls used greater amounts of select materials. While changes in nest composition vary uniquely for each species, the pattern of larger nests in northern Manitoba compared to southeastern Ontario in three of our four phylogenetically-independent comparisons suggests that birds are adapting to similar selective pressures between locations. PMID:21552515

A Bayesian network approach to predicting nest presence of thefederally-threatened piping plover (Charadrius melodus) using barrier island features

USGS Publications Warehouse

Gieder, Katherina D.; Karpanty, Sarah M.; Fraser, James D.; Catlin, Daniel H.; Gutierrez, Benjamin T.; Plant, Nathaniel G.; Turecek, Aaron M.; Thieler, E. Robert

2014-01-01

Sea-level rise and human development pose significant threats to shorebirds, particularly for species that utilize barrier island habitat. The piping plover (Charadrius melodus) is a federally-listed shorebird that nests on barrier islands and rapidly responds to changes in its physical environment, making it an excellent species with which to model how shorebird species may respond to habitat change related to sea-level rise and human development. The uncertainty and complexity in predicting sea-level rise, the responses of barrier island habitats to sea-level rise, and the responses of species to sea-level rise and human development necessitate a modelling approach that can link species to the physical habitat features that will be altered by changes in sea level and human development. We used a Bayesian network framework to develop a model that links piping plover nest presence to the physical features of their nesting habitat on a barrier island that is impacted by sea-level rise and human development, using three years of data (1999, 2002, and 2008) from Assateague Island National Seashore in Maryland. Our model performance results showed that we were able to successfully predict nest presence given a wide range of physical conditions within the model’s dataset. We found that model predictions were more successful when the range of physical conditions included in model development was varied rather than when those physical conditions were narrow. We also found that all model predictions had fewer false negatives (nests predicted to be absent when they were actually present in the dataset) than false positives (nests predicted to be present when they were actually absent in the dataset), indicating that our model correctly predicted nest presence better than nest absence. These results indicated that our approach of using a Bayesian network to link specific physical features to nest presence will be useful for modelling impacts of sea-level rise- or human-related habitat change on barrier islands. We recommend that potential users of this method utilize multiple years of data that represent a wide range of physical conditions in model development, because the model performed less well when constructed using a narrow range of physical conditions. Further, given that there will always be some uncertainty in predictions of future physical habitat conditions related to sea-level rise and/or human development, predictive models will perform best when developed using multiple, varied years of data input.

Timing of nest vegetation measurement may obscure adaptive significance of nest-site characteristics: A simulation study.

PubMed

McConnell, Mark D; Monroe, Adrian P; Burger, Loren Wes; Martin, James A

2017-02-01

Advances in understanding avian nesting ecology are hindered by a prevalent lack of agreement between nest-site characteristics and fitness metrics such as nest success. We posit this is a result of inconsistent and improper timing of nest-site vegetation measurements. Therefore, we evaluated how the timing of nest vegetation measurement influences the estimated effects of vegetation structure on nest survival. We simulated phenological changes in nest-site vegetation growth over a typical nesting season and modeled how the timing of measuring that vegetation, relative to nest fate, creates bias in conclusions regarding its influence on nest survival. We modeled the bias associated with four methods of measuring nest-site vegetation: Method 1-measuring at nest initiation, Method 2-measuring at nest termination regardless of fate, Method 3-measuring at nest termination for successful nests and at estimated completion for unsuccessful nests, and Method 4-measuring at nest termination regardless of fate while also accounting for initiation date. We quantified and compared bias for each method for varying simulated effects, ranked models for each method using AIC, and calculated the proportion of simulations in which each model (measurement method) was selected as the best model. Our results indicate that the risk of drawing an erroneous or spurious conclusion was present in all methods but greater with Method 2 which is the most common method reported in the literature. Methods 1 and 3 were similarly less biased. Method 4 provided no additional value as bias was similar to Method 2 for all scenarios. While Method 1 is seldom practical to collect in the field, Method 3 is logistically practical and minimizes inherent bias. Implementation of Method 3 will facilitate estimating the effect of nest-site vegetation on survival, in the least biased way, and allow reliable conclusions to be drawn.

An integrated runtime and compile-time approach for parallelizing structured and block structured applications

NASA Technical Reports Server (NTRS)

Agrawal, Gagan; Sussman, Alan; Saltz, Joel

1993-01-01

Scientific and engineering applications often involve structured meshes. These meshes may be nested (for multigrid codes) and/or irregularly coupled (called multiblock or irregularly coupled regular mesh problems). A combined runtime and compile-time approach for parallelizing these applications on distributed memory parallel machines in an efficient and machine-independent fashion was described. A runtime library which can be used to port these applications on distributed memory machines was designed and implemented. The library is currently implemented on several different systems. To further ease the task of application programmers, methods were developed for integrating this runtime library with compilers for HPK-like parallel programming languages. How this runtime library was integrated with the Fortran 90D compiler being developed at Syracuse University is discussed. Experimental results to demonstrate the efficacy of our approach are presented. A multiblock Navier-Stokes solver template and a multigrid code were experimented with. Our experimental results show that our primitives have low runtime communication overheads. Further, the compiler parallelized codes perform within 20 percent of the code parallelized by manually inserting calls to the runtime library.

Building of nested components by a double-nozzle droplet deposition process

NASA Astrophysics Data System (ADS)

Li, SuLi; Wei, ZhengYing; Du, Jun; Zhao, Guangxi; Wang, Xin; Lu, BingHeng

2016-07-01

According to the nested components jointed with multiple parts,a double-nozzle droplet deposition process was put forward in this paper, and the experimental system was developed. Through the research on the properties of support materials and the process of double-nozzle droplet deposition, the linkage control of the metal droplet deposition and the support material extrusion was realized, and a nested component with complex construction was fabricated directly. Compared with the traditional forming processes, this double-nozzle deposition process has the advantages of short cycle, low cost and so on. It can provide an approach way to build the nested parts.

Immunocapture reverse transcription-polymerase chain reaction combined with nested PCR greatly increases the detection of Prunus necrotic ring spot virus in the peach.

PubMed

Helguera, P R; Taborda, R; Docampo, D M; Ducasse, D A

2001-06-01

A detection system based on nested PCR after IC-RT-PCR (IC-RT-PCR-Nested PCR) was developed to improve indexing of Prunus necrotic ringspot virus in peach trees. Inhibitory effects and inconsistencies of the standard IC-RT-PCR were overcome by this approach. IC-RT-PCR-Nested PCR improved detection by three orders of magnitude compared with DAS-ELISA for the detection of PNRSV in leaves. Several different tissues were evaluated and equally consistent results were observed. The main advantages of the method are its consistency, high sensitivity and easy application in quarantine programs.

Fabrication of controlled hierarchical wrinkle structures on polydimethylsiloxane via one-step C4F8 plasma treatment

NASA Astrophysics Data System (ADS)

Miao, Liming; Cheng, Xiaoliang; Chen, Haotian; Song, Yu; Guo, Hang; Zhang, Jinxin; Chen, Xuexian; Zhang, Haixia

2018-01-01

We report a simple method for fabricating two-dimensional and nested hierarchical wrinkle structures on polydimethylsiloxane surfaces via one-step C4F8 plasma treatment that innovatively combines two approaches to monolayer wrinkle structure fabrication. The wavelengths of the two dimensions of the wrinkle structures can be controlled by plasma treatment (radio frequency (RF) power and plasma treatment time) and stretching (stretching strain and axial stretching), respectively. We also analyze the different interactions between the two dimensions of wrinkle structures with different wavelengths and explain the phenomenon using Fourier waveform superposition. The character of the two dimensions and hierarchy is obvious when the wavelengths of the two wrinkles are different. In surface wetting tests, the hierarchical wrinkle shows great hydrophobicity and keeps the stretching property under 25%.

Patch size and landscape effects on density and nesting success of grassland birds

USGS Publications Warehouse

Winter, Maiken; Johnson, Douglas H.; Shaffer, Jill A.; Donovan, Therese M.; Svedarsky, W. Daniel

2006-01-01

Current management recommendations for grassland birds in North America emphasize providing large patches of grassland habitat within landscapes that have few forest or shrubland areas. These Bird Conservation Areas are being proposed under the assumption that large patches of habitat in treeless landscapes will maintain viable populations of grassland birds. This assumption requires that patch size and landscape features affect density and nesting success of grassland birds, and that these effects are consistent among years and regions and across focal species. However, these assumptions have not yet been validated for grassland birds, and the relative importance of local vegetation structure, patch size, and landscape composition on grassland bird populations is not well known. In addition, factors influencing grassland bird nesting success have been investigated mostly in small-scale and short-duration studies. To develop management guidelines for grassland birds, we tested the spatial and temporal repeatability of the influence of patch size and landscape composition on density and nesting success of 3 grassland passerines, after controlling for local-scale vegetation structure, climate, and—when analyzing nest success—bird density. We conducted our study during 4 years (1998–2001) in 44 study plots that were set up in 3 regions of the northern tallgrass prairie in Minnesota and North Dakota, USA. In these study plots we measured density and nesting success of clay-colored sparrows (Spizella pallida), Savannah sparrows (Passerculus sandwichensis), and bobolinks (Dolichonyx oryzivorus). Statistical models indicated that density was influenced by patch size, landscape, region, and local vegetation structure more so than by local vegetation structure alone. Both magnitude and direction of the response of density to patch size varied among regions, years, and species. In contrast, the direction of landscape effects was consistent among regions, years, and between Savannah sparrows and bobolinks. In each species, this landscape effect was independent of patch size. Nesting success was not clearly influenced by patch size or landscape composition, and none of the factors that influenced avian density also influenced nesting success in any of the 3 species. General statements on “optimal habitat” for grassland birds should therefore be viewed cautiously. Instead, long-term studies in different regions as well as a deeper understanding of the local system are needed to determine which factors are most important for grassland birds in a particular area.

Methods for Casting Subterranean Ant Nests

PubMed Central

Tschinkel, Walter R.

2010-01-01

The study of subterranean ant nests has been impeded by the difficulty of rendering their structures in visible form. Here, several different casting materials are shown to make perfect casts of the underground nests of ants. Each material (dental plaster, paraffin wax, aluminum, zinc) has advantages and limitations, which are discussed. Some of the materials allow the recovery of the ants entombed in the casts, allowing a census of the ants to be connected with features of their nest architecture. The necessary equipment and procedures are described in the hope that more researchers will study this very important aspect of ant natural history. PMID:20673073

Beach erosion and nest site selection by the leatherback sea turtle Dermochelys coriacea (Testudines: Dermochelyidae) and implications for management practices at Playa Gandoca, Costa Rica.

PubMed

Spanier, Matthew J

2010-12-01

Leatherback sea turtles (Dermochelys coriacea) nest on dynamic, erosion-prone beaches. Erosive processes and resulting nest loss have long been presumed to be a hindrance to clutch survival. In order to better understand how leatherbacks cope with unstable nesting beaches, I investigated the role of beach erosion in leatherback nest site selection at Playa Gandoca, Costa Rica. I also examined the potential effect of nest relocation, a conservation strategy in place at Playa Gandoca to prevent nest loss to erosion, on the temperature of incubating clutches. I monitored changes in beach structure as a result of erosion at natural nest sites during the time the nest was laid, as well as in subsequent weeks. To investigate slope as a cue for nest site selection, I measured the slope of the beach where turtles ascended from the sea to nest, as well as the slopes at other random locations on the beach for comparison. I examined temperature differences between natural and relocated nest sites with thermocouples placed in the sand at depths typical of leatherback nests. Nests were distributed non-randomly in a clumped distribution along the length of the beach and laid at locations that were not undergoing erosion. The slope at nest sites was significantly different than at randomly chosen locations on the beach. The sand temperature at nest depths was significantly warmer at natural nest sites than at locations of relocated nests. The findings of this study suggest leatherbacks actively select nest sites that are not undergoing erosive processes, with slope potentially being used as a cue for site selection. The relocation of nests appears to be inadvertently cooling the nest environment. Due to the fact that leatherback clutches undergo temperature-dependent sex determination, the relocation of nests may be producing an unnatural male biasing of hatchlings. The results of this study suggest that the necessity of relocation practices, largely in place to protect nests from erosion, should be reevaluated to ensure the proper conservation of this critically endangered species.

MAGNETIC FIELD OF THE VELA C MOLECULAR CLOUD

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

Kusune, Takayoshi; Sugitani, Koji; Nakamura, Fumitaka

We have performed extensive near-infrared ( JHK {sub s}) imaging polarimetry toward the Vela C molecular cloud, which covers the five high-density sub-regions (North, Centre-Ridge, Centre-Nest, South-Ridge, and South-Nest) with distinct morphological characteristics. The obtained polarization vector map shows that three of these sub-regions have distinct plane-of-the-sky (POS) magnetic-field characteristics according to the morphological characteristics. (1) In the Centre-Ridge sub-region, a dominating ridge, the POS magnetic field is mostly perpendicular to the ridge. (2) In the Centre-Nest sub-region, a structure having a slightly extended nest of filaments, the POS magnetic field is nearly parallel to its global elongation. (3) Inmore » the South-Nest sub-region, which has a network of small filaments, the POS magnetic field appears to be chaotic. By applying the Chandrasekhar–Fermi method, we derived the POS magnetic field strength as ∼70–310 μ G in the Centre-Ridge, Centre-Nest, and South-Ridge sub-regions. In the South-Nest sub-region, the dispersion of polarization angles is too large to apply the C-F method. Because the velocity dispersion in this sub-region is not greater than those in the other sub-regions, we suggest that the magnetic field in this sub-region is weaker than those in other sub-regions. We also discuss the relationship between the POS magnetic field (configuration and strength) and the cloud structure of each sub-region.« less

Emergence of consensus as a modular-to-nested transition in communication dynamics

NASA Astrophysics Data System (ADS)

Borge-Holthoefer, Javier; Baños, Raquel A.; Gracia-Lázaro, Carlos; Moreno, Yamir

2017-01-01

Online social networks have transformed the way in which humans communicate and interact, leading to a new information ecosystem where people send and receive information through multiple channels, including traditional communication media. Despite many attempts to characterize the structure and dynamics of these techno-social systems, little is known about fundamental aspects such as how collective attention arises and what determines the information life-cycle. Current approaches to these problems either focus on human temporal dynamics or on semiotic dynamics. In addition, as recently shown, information ecosystems are highly competitive, with humans and memes striving for scarce resources -visibility and attention, respectively. Inspired by similar problems in ecology, here we develop a methodology that allows to cast all the previous aspects into a compact framework and to characterize, using microblogging data, information-driven systems as mutualistic networks. Our results show that collective attention around a topic is reached when the user-meme network self-adapts from a modular to a nested structure, which ultimately allows minimizing competition and attaining consensus. Beyond a sociological interpretation, we explore such resemblance to natural mutualistic communities via well-known dynamics of ecological systems.

Emergence of consensus as a modular-to-nested transition in communication dynamics.

PubMed

Borge-Holthoefer, Javier; Baños, Raquel A; Gracia-Lázaro, Carlos; Moreno, Yamir

2017-01-30

Online social networks have transformed the way in which humans communicate and interact, leading to a new information ecosystem where people send and receive information through multiple channels, including traditional communication media. Despite many attempts to characterize the structure and dynamics of these techno-social systems, little is known about fundamental aspects such as how collective attention arises and what determines the information life-cycle. Current approaches to these problems either focus on human temporal dynamics or on semiotic dynamics. In addition, as recently shown, information ecosystems are highly competitive, with humans and memes striving for scarce resources -visibility and attention, respectively. Inspired by similar problems in ecology, here we develop a methodology that allows to cast all the previous aspects into a compact framework and to characterize, using microblogging data, information-driven systems as mutualistic networks. Our results show that collective attention around a topic is reached when the user-meme network self-adapts from a modular to a nested structure, which ultimately allows minimizing competition and attaining consensus. Beyond a sociological interpretation, we explore such resemblance to natural mutualistic communities via well-known dynamics of ecological systems.

Emergence of consensus as a modular-to-nested transition in communication dynamics

PubMed Central

Borge-Holthoefer, Javier; Baños, Raquel A.; Gracia-Lázaro, Carlos; Moreno, Yamir

2017-01-01

Online social networks have transformed the way in which humans communicate and interact, leading to a new information ecosystem where people send and receive information through multiple channels, including traditional communication media. Despite many attempts to characterize the structure and dynamics of these techno-social systems, little is known about fundamental aspects such as how collective attention arises and what determines the information life-cycle. Current approaches to these problems either focus on human temporal dynamics or on semiotic dynamics. In addition, as recently shown, information ecosystems are highly competitive, with humans and memes striving for scarce resources –visibility and attention, respectively. Inspired by similar problems in ecology, here we develop a methodology that allows to cast all the previous aspects into a compact framework and to characterize, using microblogging data, information-driven systems as mutualistic networks. Our results show that collective attention around a topic is reached when the user-meme network self-adapts from a modular to a nested structure, which ultimately allows minimizing competition and attaining consensus. Beyond a sociological interpretation, we explore such resemblance to natural mutualistic communities via well-known dynamics of ecological systems. PMID:28134358

Mapping forest canopy gaps using air-photo interpretation and ground surveys

USGS Publications Warehouse

Fox, T.J.; Knutson, M.G.; Hines, R.K.

2000-01-01

Canopy gaps are important structural components of forested habitats for many wildlife species. Recent improvements in the spatial accuracy of geographic information system tools facilitate accurate mapping of small canopy features such as gaps. We compared canopy-gap maps generated using ground survey methods with those derived from air-photo interpretation. We found that maps created from high-resolution air photos were more accurate than those created from ground surveys. Errors of omission were 25.6% for the ground-survey method and 4.7% for the air-photo method. One variable of inter est in songbird research is the distance from nests to gap edges. Distances from real and simulated nests to gap edges were longer using the ground-survey maps versus the air-photo maps, indicating that gap omission could potentially bias the assessment of spatial relationships. If research or management goals require location and size of canopy gaps and specific information about vegetation structure, we recommend a 2-fold approach. First, canopy gaps can be located and the perimeters defined using 1:15,000-scale or larger aerial photographs and the methods we describe. Mapped gaps can then be field-surveyed to obtain detailed vegetation data.

Nest survival relative to patch size in a highly fragmented shortgrass prairie landscape

USGS Publications Warehouse

Skagen, S.K.; Yackel Adams, A.A.; Adams, R.D.

2005-01-01

Understanding the influences of habitat fragmentation on vertebrate populations is essential for the protection and ecological restoration of strategic sites for native species. We examined the effects of prairie fragmentation on avian reproductive success using artificial and natural nests on 26 randomly selected, privately owned patches of shortgrass prairie ranging in size from 7 to 454 ha within a cropland matrix in Washington County, Colorado, summer 2000. Survival trends of artificial and natural nests differed. Daily survival of artificial nests increased with patch size up to about 65 ha and differed little at larger patch sizes, whereas daily survival of Lark Bunting (Calamospiza melanocorys) and Horned Lark (Eremophila alpestris) nests decreased with increasing size of the grassland patch. We hypothesize that our unexpected findings of lower survival of natural nests with increasing patch sizes and different trends between artificial and natural nests are due to the particular structure of predator communities in our study area and the ways in which individual predators respond to artificial and natural nests. We recommend that the value of small habitat patches in highly fragmented landscapes not be overlooked.

The Nest Growth of the Neotropical Mound-Building Termite, Cornitermes cumulans: A Micromorphological Analysis

PubMed Central

Cosarinsky, Marcela I.

2011-01-01

The nests of Cornitermes cumulans K. (Isoptera: Termitidae), a very common termite in South American grasslands, display notable morphological transformations during the development of the colony. Young colonies inhabit small subterranean nests that develop into large, conspicuous, epigean mounds, inhabited by very populous colonies. Those macromorphological transformations are accompanied by micromorphological changes occurring gradually in the nest walls. The micromorphological changes during nest development described in the present study expand on previous macromorphological descriptions by explaining the re-organization of the soil components during nest growth. In subterranean nests, walls are composed of piles of lensshaped aggregates of soil material, each one surrounded by a thin organic coating. As the nest grows, mound walls are constructed by disassembling this first lenticular structure and rearranging the materials in a new fabric, where sand grains are loosely distributed among soil microaggregates of organic matter and clay. This is also a temporary construction, because the walls of large nests are composed of a porous mass of sands densely cemented with organic matter and clay in the mound, and a compact mass of the same components in the floor. PMID:22224433

Osprey distribution, abundance, and status in western North America: III. The Baja California and Gulf of California population

USGS Publications Warehouse

Henny, C.J.; Anderson, D.W.

1979-01-01

-An estimated 810 ? 55 pairs (minimum estimate) of ospreys (Pandion haliaetus) were nesting in the study area during our survey (24 March-l April 1977). Approximately 174 pairs nested along the Pacific side of Baja California, 255 pairs along the gulf side, 187 pairs on the Midriff Islands, and 194 pairs in coastal Sonora and Sinaloa. Most nested on cliffs adjacent to the sea (59%); some nested on cactus in flat terrain (26%). Seven per cent nested on the ground, three percent nested in mangroves and other trees in the southern portion of the study area,.and four percent nested on man-made structures. The extreme northwestern Baja California population that was extirpated early in this century has not recovered. However, several populations immediately to the south along the Pacific Coast now appear stationary. Pesticide residues in osprey eggs from Mexico were among the lowest reported for the species in North America.

Superpredator proximity and landscape characteristics alters nest site selection and breeding success of a subordinate predator.

PubMed

Atuo, Fidelis Akunke; O'Connell, Timothy John

2018-03-01

Selecting nesting habitat that minimizes predation risk but maximizes foraging success is one of the most important decisions in avian life history. This takes on added complexity when a predator is faced with the challenge of avoiding fellow predators. We assessed the importance of local and landscape vegetation, food abundance, and predation risk on nest site selection and nest survival in a subordinate raptor (Mississippi Kite; Ictinia mississippiensis) nesting in proximity to two superpredators, Red-tailed hawk (Buteo jamaicensis) and Great horned owl (Bubo virginianus). All three species nested in trees in a grassland landscape. In this landscape, kites favored upland trees and shrubs, avoiding their more typical riparian forest association elsewhere in the species' range. Compared to random conditions, kites selected nest sites with high tree density and more closed canopy in the surrounding area. Mississippi Kite selection was not related to food abundance but could be explained by the presence of superpredators (i.e., hawks and owls) selecting riparian woodland for their nests. Nest survival declined with proximity to superpredator nesting sites. Overall, our study demonstrates how landscape structure and superior predators shapes predation risk for subordinate predators. Our results emphasize the importance of spatial heterogeneity in presenting opportunities for subordinate predators to coexist in a landscape with important superpredators.

Coevolutionary diversification creates nested-modular structure in phage–bacteria interaction networks

PubMed Central

Beckett, Stephen J.; Williams, Hywel T. P.

2013-01-01

Phage and their bacterial hosts are the most diverse and abundant biological entities in the oceans, where their interactions have a major impact on marine ecology and ecosystem function. The structure of interaction networks for natural phage–bacteria communities offers insight into their coevolutionary origin. At small phylogenetic scales, observed communities typically show a nested structure, in which both hosts and phages can be ranked by their range of resistance and infectivity, respectively. A qualitatively different multi-scale structure is seen at larger phylogenetic scales; a natural assemblage sampled from the Atlantic Ocean displays large-scale modularity and local nestedness within each module. Here, we show that such ‘nested-modular’ interaction networks can be produced by a simple model of host–phage coevolution in which infection depends on genetic matching. Negative frequency-dependent selection causes diversification of hosts (to escape phages) and phages (to track their evolving hosts). This creates a diverse community of bacteria and phage, maintained by kill-the-winner ecological dynamics. When the resulting communities are visualized as bipartite networks of who infects whom, they show the nested-modular structure characteristic of the Atlantic sample. The statistical significance and strength of this observation varies depending on whether the interaction networks take into account the density of the interacting strains, with implications for interpretation of interaction networks constructed by different methods. Our results suggest that the apparently complex community structures associated with marine bacteria and phage may arise from relatively simple coevolutionary origins. PMID:24516719

Waterbird nest-site selection is influenced by neighboring nests and island topography

USGS Publications Warehouse

Hartman, Christopher; Ackerman, Joshua T.; Takekawa, John Y.; Herzog, Mark

2016-01-01

Avian nest-site selection is influenced by factors operating across multiple spatial scales. Identifying preferred physical characteristics (e.g., topography, vegetation structure) can inform managers to improve nesting habitat suitability. However, social factors (e.g., attraction, territoriality, competition) can complicate understanding physical characteristics preferred by nesting birds. We simultaneously evaluated the physical characteristics and social factors influencing selection of island nest sites by colonial-nesting American avocets (Recurvirostra americana) and Forster's terns (Sterna forsteri) at 2 spatial scales in San Francisco Bay, 2011–2012. At the larger island plot (1 m2) scale, we used real-time kinematics to produce detailed topographies of nesting islands and map the distribution of nests. Nesting probability was greatest in island plots between 0.5 m and 1.5 m above the water surface, at distances <10 m from the water's edge, and of moderately steep (avocets) or flat (terns) slopes. Further, avocet and tern nesting probability increased as the number of nests initiated in adjacent plots increased up to a peak of 11–12 tern nests, and then decreased thereafter. Yet, avocets were less likely to nest in plots adjacent to plots with nesting avocets, suggesting an influence of intra-specific territoriality. At the smaller microhabitat scale, or the area immediately surrounding the nest, we compared topography, vegetation, and distance to nearest nest between nest sites and paired random sites. Topography had little influence on selection of the nest microhabitat. Instead, nest sites were more likely to have vegetation present, and greater cover, than random sites. Finally, avocet, and to a lesser extent tern, nest sites were closer to other active conspecific or heterospecific nests than random sites, indicating that social attraction played a role in selection of nest microhabitat. Our results demonstrate key differences in nest-site selection between co-occurring avocets and terns, and indicate the effects of physical characteristics and social factors on selection of nesting habitat are dependent on the spatial scale examined. Moreover, these results indicate that islands with abundant area between 0.5 m and 1.5 m above the water surface, within 10 m of the water's edge, and containing a mosaic of slopes ranging from flat to moderately steep would provide preferred nesting habitat for avocets and terns. © 2016 The Wildlife Society.

How does vegetation structure influence woodpeckers and secondary cavity nesting birds in African cork oak forest?

NASA Astrophysics Data System (ADS)

Segura, Amalia

2017-08-01

The Great Spotted Woodpecker provides important information about the status of a forest in terms of structure and age. As a primary cavity creator, it provides small-medium size cavities for passerines. However, despite its interest as an ecosystem engineer, studies of this species in Africa are scarce. Here, spatially explicit predictive models were used to investigate how forest structural variables are related to both the Great Spotted Woodpecker and secondary cavity nesting birds in Maamora cork oak forest (northwest Morocco). A positive association between Great Spotted Woodpecker and both dead-tree density and large mature trees (>60 cm dbh) was found. This study area, Maamora, has an old-growth forest structure incorporating a broad range of size and condition of live and dead trees, favouring Great Spotted Woodpecker by providing high availability of foraging and excavating sites. Secondary cavity nesting birds, represented by Great Tit, African Blue Tit, and Hoopoe, were predicted by Great Spotted Woodpecker detections. The findings suggest that the conservation of the Maamora cork oak forest could be key to maintaining these hole-nesting birds. However, this forest is threatened by forestry practises and livestock overgrazing and the challenge is therefore to find sustainable management strategies that ensure conservation while allowing its exploitation.

Habitat edges have weak effects on duck nest survival at local spatial scales

USGS Publications Warehouse

Raquel, Amelia J; Ringelman, Kevin M.; Ackerman, Joshua T.; Eadie, John M.

2015-01-01

Edge effects on nesting success have been documented in breeding birds in a variety of contexts, but there is still uncertainty in how edge type and spatial scale determine the magnitude and detectability of edge effects. Habitat edges are often viewed as predator corridors that surround or penetrate core habitat and increase the risk of predation for nearby nests. We studied the effects of three different types of potential predator corridors (main perimeter roads, field boundaries, and ATV trails within fields) on waterfowl nest survival in California. We measured the distance from duck nests to the nearest edge of each type, and used distance as a covariate in a logistic exposure analysis of nest survival. We found only weak evidence for edge effects due to predation. The best supported model of nest survival included all three distance categories, and while all coefficient estimates were positive (indicating that survival increased with distance from edge), 85% coefficient confidence intervals approached or bounded zero indicating an overall weak effect of habitat edges on nest success. We suggest that given the configuration of edges at our site, there may be few areas far enough from hard edges to be considered ‘core’ habitat, making edge effects on nest survival particularly difficult to detect.

Soil attributes drive nest-site selection by the campo miner Geositta poeciloptera.

PubMed

Meireles, Ricardo Camargos de; Teixeira, João Paulo Gusmão; Solar, Ricardo; Vasconcelos, Bruno Nery F; Fernandes, Raphael B A; Lopes, Leonardo Esteves

2018-01-01

Substrate type is a key-factor in nest-site selection and nest architecture of burrowing birds. However, little is known about which factors drive nest-site selection for these species, especially in the tropics. We studied the influence of soil attributes on nest-site selection by the campo miner Geositta poeciloptera, an open grassland bird that builds its nests within soil cavities. For all nests found, we measured the depth of the nest cavity and the resistance of the soil to penetration, and identified the soil horizon in which the nest was located. In soil banks with nests, we collected soil samples for granulometric analysis around each nest cavity, while in soil banks without nests we collected these samples at random points. From 43 nests found, 86% were located in the deeper soil horizons (C-horizon), and only 14% in the shallower horizons (B-horizon). Granulometric analysis showed that the C-horizons possessed a high similar granulometric composition, with high silt and low clay contents. These characteristics are associated with a low degree of structural development of the soil, which makes it easier to excavate. Contrarily, soil resistance to penetration does not seem to be an important criterion for nest site selection, although nests in more resistant the soils tend to have shallower nest cavities. Among the soil banks analyzed, 40% of those without cavities possessed a larger proportion of B-horizon relative to the C-horizon, and their texture was more clayey. On the other hand, almost all soil banks containing nest cavities had a larger C-horizon and a silty texture, indicating that soil attributes drive nest-site selection by G. poeciloptera. Thus, we conclude that the patchy distribution of G. poeciloptera can attributed to the infrequent natural exposure of the C-horizon in the tropical region, where well developed, deep and permeable soils are more common.

Soil attributes drive nest-site selection by the campo miner Geositta poeciloptera

PubMed Central

Teixeira, João Paulo Gusmão; Solar, Ricardo; Vasconcelos, Bruno Nery F.; Fernandes, Raphael B. A.; Lopes, Leonardo Esteves

2018-01-01

Substrate type is a key-factor in nest-site selection and nest architecture of burrowing birds. However, little is known about which factors drive nest-site selection for these species, especially in the tropics. We studied the influence of soil attributes on nest-site selection by the campo miner Geositta poeciloptera, an open grassland bird that builds its nests within soil cavities. For all nests found, we measured the depth of the nest cavity and the resistance of the soil to penetration, and identified the soil horizon in which the nest was located. In soil banks with nests, we collected soil samples for granulometric analysis around each nest cavity, while in soil banks without nests we collected these samples at random points. From 43 nests found, 86% were located in the deeper soil horizons (C-horizon), and only 14% in the shallower horizons (B-horizon). Granulometric analysis showed that the C-horizons possessed a high similar granulometric composition, with high silt and low clay contents. These characteristics are associated with a low degree of structural development of the soil, which makes it easier to excavate. Contrarily, soil resistance to penetration does not seem to be an important criterion for nest site selection, although nests in more resistant the soils tend to have shallower nest cavities. Among the soil banks analyzed, 40% of those without cavities possessed a larger proportion of B-horizon relative to the C-horizon, and their texture was more clayey. On the other hand, almost all soil banks containing nest cavities had a larger C-horizon and a silty texture, indicating that soil attributes drive nest-site selection by G. poeciloptera. Thus, we conclude that the patchy distribution of G. poeciloptera can attributed to the infrequent natural exposure of the C-horizon in the tropical region, where well developed, deep and permeable soils are more common. PMID:29381768

Density and success of bird nests relative to grazing on western Montana grasslands

USGS Publications Warehouse

Fondell, Thomas F.; Ball, I.J.

2004-01-01

Grassland birds are declining at a faster rate than any other group of North American bird species. Livestock grazing is the primary economic use of grasslands in the western United States, but the effects of this use on distribution and productivity of grassland birds are unclear. We examined nest density and success of ground-nesting birds on grazed and ungrazed grasslands in western Montana. In comparison to grazed plots, ungrazed plots had reduced forb cover, increased litter cover, increased litter depth, and increased visual obstruction readings (VOR) of vegetation. Nest density among 10 of 11 common bird species was most strongly correlated with VOR of plots, and greatest nest density for each species occurred where mean VOR of the plot was similar to mean VOR at nests. Additionally, all bird species were relatively consistent in their choice of VOR at nests despite substantial differences in VOR among plots. We suggest that birds selected plots based in part on availability of suitable nest sites and that variation in nest density relative to grazing reflected the effect of grazing on availability of nest sites. Nest success was similar between grazed plots and ungrazed plots for two species but was lower for nests on grazed plots than on ungrazed plots for two other species because of increased rates of predation, trampling, or parasitism by brown-headed cowbirds (Molothrus ater). Other species nested almost exclusively on ungrazed plots (six species) or grazed plots (one species), precluding evaluation of the effects of grazing on nest success. We demonstrate that each species in a diverse suite of ground-nesting birds preferentially used certain habitats for nesting and that grazing altered availability of preferred nesting habitats through changes in vegetation structure and plant species composition. We also show that grazing directly or indirectly predisposed some bird species to increased nesting mortality. Management alternatives that avoid intensive grazing during the breeding season would be expected to benefit many grassland bird species.

Salient eyes deter conspecific nest intruders in wild jackdaws (Corvus monedula).

PubMed

Davidson, Gabrielle L; Clayton, Nicola S; Thornton, Alex

2014-02-01

Animals often respond fearfully when encountering eyes or eye-like shapes. Although gaze aversion has been documented in mammals when avoiding group-member conflict, the importance of eye coloration during interactions between conspecifics has yet to be examined in non-primate species. Jackdaws (Corvus monedula) have near-white irides, which are conspicuous against their dark feathers and visible when seen from outside the cavities where they nest. Because jackdaws compete for nest sites, their conspicuous eyes may act as a warning signal to indicate that a nest is occupied and deter intrusions by conspecifics. We tested whether jackdaws' pale irides serve as a deterrent to prospecting conspecifics by comparing prospectors' behaviour towards nest-boxes displaying images with bright eyes (BEs) only, a jackdaw face with natural BEs, or a jackdaw face with dark eyes. The jackdaw face with BEs was most effective in deterring birds from making contact with nest-boxes, whereas both BE conditions reduced the amount of time jackdaws spent in proximity to the image. We suggest BEs in jackdaws may function to prevent conspecific competitors from approaching occupied nest sites.

Multilevel Analysis Methods for Partially Nested Cluster Randomized Trials

ERIC Educational Resources Information Center

Sanders, Elizabeth A.

2011-01-01

This paper explores multilevel modeling approaches for 2-group randomized experiments in which a treatment condition involving clusters of individuals is compared to a control condition involving only ungrouped individuals, otherwise known as partially nested cluster randomized designs (PNCRTs). Strategies for comparing groups from a PNCRT in the…

Reproductive success of migratory birds in habitat sources and sinks

Treesearch

Therese M. Donovan; Frank R. , III Thompson; John Faaborg; John R. Probst

1995-01-01

Fragmentation of breeding habitat in North America has been implicated in the decline of forest-nesting, Neotropical migrant birds. We used a comparative approach to examine the effects of fragmentation on three forest-nesting migrants: Ovenbird (Seiurus aurocapillus), Red-eyed Vireo (Vireo ofivaceus), and Wood Thrush (...

Green-tailed Towhee response to prescribed fire in montane shrubland

USGS Publications Warehouse

Jehle, G.; Savidge, J.A.; Kotliar, N.B.

2006-01-01

Fire alters the structure and composition of shrublands and affects habitat quality for the associated avifauna. Because shrubland ecosystems have been greatly reduced from their original extent in western North America and fire is increasingly being used to manage these landscapes, a better understanding of how fire affects the associated vegetation and wildlife is imperative. We evaluated the response of Green-tailed Towhees (Pipilo chlorurus) to prescribed fire in the montane shrublands of Rocky Mountain National Park, Colorado during 2002 and 2003. Three to five years following prescribed burning, Green-tailed Towhee density and shrub cover were generally higher in unburned areas. Nests (n = 179) were located in unburned vegetation; within burned sites, all nests were in remnant patches. Green-tailed Towhee nest survival was 57% (95% CI = 49%-65%) across the two years of the study. More than half of the nests were in common juniper (Juniperus communis) shrubs, and nest survival was higher for nests in junipers than those in other shrub species. Daily nest survival rates were lower at the site with the highest density of towhees and declined over the breeding season. With regard to shrub cover, opposite trends were observed for nest-site selection and nest survival: nest plots had greater shrub cover than non-nest plots, but nest survival decreased with increasing shrub cover. Because shrub cover affects towhee density and nest survival in conflicting ways, fire management at Rocky Mountain National Park alters both habitat availability and suitability for Green-tailed Towhees. ?? The Cooper Ornithological Society 2006.

Coupled large-eddy simulation and morphodynamics of a large-scale river under extreme flood conditions

NASA Astrophysics Data System (ADS)

Khosronejad, Ali; Sotiropoulos, Fotis; Stony Brook University Team

2016-11-01

We present a coupled flow and morphodynamic simulations of extreme flooding in 3 km long and 300 m wide reach of the Mississippi River in Minnesota, which includes three islands and hydraulic structures. We employ the large-eddy simulation (LES) and bed-morphodynamic modules of the VFS-Geophysics model to investigate the flow and bed evolution of the river during a 500 year flood. The coupling of the two modules is carried out via a fluid-structure interaction approach using a nested domain approach to enhance the resolution of bridge scour predictions. The geometrical data of the river, islands and structures are obtained from LiDAR, sub-aqueous sonar and in-situ surveying to construct a digital map of the river bathymetry. Our simulation results for the bed evolution of the river reveal complex sediment dynamics near the hydraulic structures. The numerically captured scour depth near some of the structures reach a maximum of about 10 m. The data-driven simulation strategy we present in this work exemplifies a practical simulation-based-engineering-approach to investigate the resilience of infrastructures to extreme flood events in intricate field-scale riverine systems. This work was funded by a Grant from Minnesota Dept. of Transportation.

Phylogenetic analysis of honey bee behavioral evolution.

PubMed

Raffiudin, Rika; Crozier, Ross H

2007-05-01

DNA sequences from three mitochondrial (rrnL, cox2, nad2) and one nuclear gene (itpr) from all 9 known honey bee species (Apis), a 10th possible species, Apis dorsata binghami, and three outgroup species (Bombus terrestris, Melipona bicolor and Trigona fimbriata) were used to infer Apis phylogenetic relationships using Bayesian analysis. The dwarf honey bees were confirmed as basal, and the giant and cavity-nesting species to be monophyletic. All nodes were strongly supported except that grouping Apis cerana with A. nigrocincta. Two thousand post-burnin trees from the phylogenetic analysis were used in a Bayesian comparative analysis to explore the evolution of dance type, nest structure, comb structure and dance sound within Apis. The ancestral honey bee species was inferred with high support to have nested in the open, and to have more likely than not had a silent vertical waggle dance and a single comb. The common ancestor of the giant and cavity-dwelling bees is strongly inferred to have had a buzzing vertical directional dance. All pairwise combinations of characters showed strong association, but the multiple comparisons problem reduces the ability to infer associations between states between characters. Nevertheless, a buzzing dance is significantly associated with cavity-nesting, several vertical combs, and dancing vertically, a horizontal dance is significantly associated with a nest with a single comb wrapped around the support, and open nesting with a single pendant comb and a silent waggle dance.

Improved assay to detect Plasmodium falciparum using an uninterrupted, semi-nested PCR and quantitative lateral flow analysis

PubMed Central

2013-01-01

Background A rapid, non-invasive, and inexpensive point-of-care (POC) diagnostic for malaria followed by therapeutic intervention would improve the ability to control infection in endemic areas. Methods A semi-nested PCR amplification protocol is described for quantitative detection of Plasmodium falciparum and is compared to a traditional nested PCR. The approach uses primers that target the P. falciparum dihydrofolate reductase gene. Results This study demonstrates that it is possible to perform an uninterrupted, asymmetric, semi-nested PCR assay with reduced assay time to detect P. falciparum without compromising the sensitivity and specificity of the assay using saliva as a testing matrix. Conclusions The development of this PCR allows nucleic acid amplification without the need to transfer amplicon from the first PCR step to a second reaction tube with nested primers, thus reducing both the chance of contamination and the time for analysis to < two hours. Analysis of the PCR amplicon yield was adapted to lateral flow detection using the quantitative up-converting phosphor (UCP) reporter technology. This approach provides a basis for migration of the assay to a POC microfluidic format. In addition the assay was successfully evaluated with oral samples. Oral fluid collection provides a simple non-invasive method to collect clinical samples. PMID:23433252

Factors influencing nesting success of king eiders on northern Alaska's Coastal Plain

USGS Publications Warehouse

Bentzen, R.L.; Powell, A.N.; Suydam, R.S.

2008-01-01

King eider (Somateria spectabilis) populations have declined markedly in recent decades for unknown reasons. Nest survival is one component of recruitment, and a female's chance of reproductive success increases with her ability to choose an appropriate nesting strategy. We estimated variation in daily nest survival of king eiders at 2 sites, Teshekpuk and Kuparuk, Alaska, USA, 2002-2005. We evaluated both a priori and exploratory competing models of nest survival that considered importance of nest concealment, seclusion, and incubation constancy as strategies to avoid 2 primary egg predators, avian (Larus spp., Stercorarius spp., and Corvus corax) and fox (Alopex lagopus). We used generalized nonlinear techniques to examine factors affecting nest survival rates and information-theoretic approaches to select among competing models. Estimated nest survival, accounting for a nest visitation effect, varied considerably across sites and years (0.21-0.57); however, given our small sample size, much of this variation maybe attributable to sampling variation (??process = 0.007, 95% CI: 0.003-0.070). Nest survival was higher at Kuparuk than Teshekpuk in all years; however, due to the correlative nature of our data, we cannot determine the underlying causes with any certainty. We found mixed support for the concealed breeding strategy, females derived no benefit from nesting in areas with more willow (Salix spp.; measure of concealment) except that the observer effect diminished as willow cover increased. We suggest these patterns are due to conflicting predation pressures. Nest survival was not higher on islands (measure of seclusion) or with increased incubation constancy but was higher post-fox removal, indicating that predator control on breeding grounds could be a viable management option. Nest survival was negatively affected by our nest visitations, most likely by exposing the nest to avian scavengers. We recommend precautions be taken to limit the effects of nest visits in future studies and to consider them as a possible negative bias in estimated nest survival. Future models of the impacts of development within the breeding grounds of king eider should consider the influence of humans in the vicinity of nests.

Unique crystal structure of a novel surfactant protein from the foam nest of the frog Leptodactylus vastus.

PubMed

Cavalcante Hissa, Denise; Arruda Bezerra, Gustavo; Birner-Gruenberger, Ruth; Paulino Silva, Luciano; Usón, Isabel; Gruber, Karl; Maciel Melo, Vânia Maria

2014-02-10

Breeding by releasing eggs into stable biofoams ("foam nests") is a peculiar reproduction mode within anurans, fish, and tunicates; not much is known regarding the biochemistry or molecular mechanisms involved. Lv-ranaspumin (Lv-RSN-1) is the predominant protein from the foam nest of the frog Leptodactylus vastus. This protein shows natural surfactant activity, which is assumed to be crucial for stabilizing foam nests. We elucidated the amino acid sequence of Lv-RSN-1 by de novo sequencing with mass-spectrometry and determined the high-resolution X-ray structure of the protein. It has a unique fold mainly composed of a bundle of 11 α-helices and two small antiparallel β-strands. Lv-RSN-1 has a surface rich in hydrophilic residues and a lipophilic cavity in the region of the antiparallel β-sheet. It possesses intrinsic surface-active properties, reducing the surface tension of water from 73 to 61 mN m(-1) (15 μg mL(-1)). Lv-RSN-1 belongs to a new class of surfactants proteins for which little has been reported regarding structure or function. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Quantitative analysis of American woodcock nest and brood habitat

USGS Publications Warehouse

Bourgeois, A.; Keppie, Daniel M.; Owen, Ray B.

1977-01-01

Sixteen nest and 19 brood sites of American woodcock (Philohela minoI) were examined in northern lower Michigan between 15 April and 15 June 1974 to determine habitat structure associated with these sites. Woodcock hens utilized young, second-growth forest stands which were similar in species composition for both nesting and brood rearing. A multi-varIate discriminant function analysis revealed a significant (P< 0.05) difference, however, in habitat structure. Nest habitat was characterized by lower tree density (2176 trees/ha) and basal area (8.6 m2/ha), by being close to forest openings (7 m) and by being situated on dry, relatively well drained sites. In contrast, woodcock broods were located in sites that had nearly twice the tree density (3934 trees/hal and basal area (16.5 m2/ha), was located over twice as far from forest openings (18 m) and generally occurred on damp sites, near (8 m) standing water. Importance of the habitat features to the species and possible management implications are discussed.

Competition can lead to unexpected patterns in tropical ant communities

NASA Astrophysics Data System (ADS)

Ellwood, M. D. Farnon; Blüthgen, Nico; Fayle, Tom M.; Foster, William A.; Menzel, Florian

2016-08-01

Ecological communities are structured by competitive, predatory, mutualistic and parasitic interactions combined with chance events. Separating deterministic from stochastic processes is possible, but finding statistical evidence for specific biological interactions is challenging. We attempt to solve this problem for ant communities nesting in epiphytic bird's nest ferns (Asplenium nidus) in Borneo's lowland rainforest. By recording the frequencies with which each and every single ant species occurred together, we were able to test statistically for patterns associated with interspecific competition. We found evidence for competition, but the resulting co-occurrence pattern was the opposite of what we expected. Rather than detecting species segregation-the classical hallmark of competition-we found species aggregation. Moreover, our approach of testing individual pairwise interactions mostly revealed spatially positive rather than negative associations. Significant negative interactions were only detected among large ants, and among species of the subfamily Ponerinae. Remarkably, the results from this study, and from a corroborating analysis of ant communities known to be structured by competition, suggest that competition within the ants leads to species aggregation rather than segregation. We believe this unexpected result is linked with the displacement of species following asymmetric competition. We conclude that analysing co-occurrence frequencies across complete species assemblages, separately for each species, and for each unique pairwise combination of species, represents a subtle yet powerful way of detecting structure and compartmentalisation in ecological communities.

Fibroblast growth factor-10 signals development of von Brunn's nests in the exstrophic bladder

PubMed Central

Eastman, Rocky; Leaf, Elizabeth M.; Zhang, Dianzhong; True, Lawrence D.; Sweet, Robert M.; Seidel, Kristy; Siebert, Joseph R.; Grady, Richard; Mitchell, Michael E.

2010-01-01

von Brunn's nests have long been recognized as precursors of benign lesions of the urinary bladder mucosa. We report here that von Brunn's nests are especially prevalent in the exstrophic bladder, a birth defect that predisposes the patient to formation of bladder cancer. Cells of von Brunn's nest were found to coalesce into a stratified, polarized epithelium which surrounds itself with a capsule-like structure rich in types I, III, and IV collagen. Histocytochemical analysis and keratin profiling demonstrated that nested cells exhibited a phenotype similar, but not identical, to that of urothelial cells of transitional epithelium. Immunostaining and in situ hybridization analysis of exstrophic tissue demonstrated that the FGF-10 receptor is synthesized and retained by cells of von Brunn's nest. In contrast, FGF-10 is synthesized and secreted by mesenchymal fibroblasts via a paracrine pathway that targets basal epithelial cells of von Brunn's nests. Small clusters of 10pRp cells, positive for both FGF-10 and its receptor, were observed both proximal to and inside blood vessels in the lamina propria. The collective evidence points to a mechanism where von Brunn's nests develop under the control of the FGF-10 signal transduction system and suggests that 10pRp cells may be the original source of nested cells. PMID:20719973

Nested high-resolution large-eddy simulations in WRF to support wind power

NASA Astrophysics Data System (ADS)

Mirocha, J.; Kirkil, G.; Kosovic, B.; Lundquist, J. K.

2009-12-01

The WRF model’s grid nesting capability provides a potentially powerful framework for simulating flow over a wide range of scales. One such application is computation of realistic inflow boundary conditions for large eddy simulations (LES) by nesting LES domains within mesoscale domains. While nesting has been widely and successfully applied at GCM to mesoscale resolutions, the WRF model’s nesting behavior at the high-resolution (Δx < 1000m) end of the spectrum is less well understood. Nesting LES within msoscale domains can significantly improve turbulent flow prediction at the scale of a wind park, providing a basis for superior site characterization, or for improved simulation of turbulent inflows encountered by turbines. We investigate WRF’s grid nesting capability at high mesh resolutions using nested mesoscale and large-eddy simulations. We examine the spatial scales required for flow structures to equilibrate to the finer mesh as flow enters a nest, and how the process depends on several parameters, including grid resolution, turbulence subfilter stress models, relaxation zones at nest interfaces, flow velocities, surface roughnesses, terrain complexity and atmospheric stability. Guidance on appropriate domain sizes and turbulence models for LES in light of these results is provided This work is performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 LLNL-ABS-416482

Association between nighttime artificial light pollution and sea turtle nest density along Florida coast: A geospatial study using VIIRS remote sensing data.

PubMed

Hu, Zhiyong; Hu, Hongda; Huang, Yuxia

2018-08-01

Artificial lighting at night has becoming a new type of pollution posing an important anthropogenic environmental pressure on organisms. The objective of this research was to examine the potential association between nighttime artificial light pollution and nest densities of the three main sea turtle species along Florida beaches, including green turtles, loggerheads, and leatherbacks. Sea turtle survey data was obtained from the "Florida Statewide Nesting Beach Survey program". We used the new generation of satellite sensor "Visible Infrared Imaging Radiometer Suite (VIIRS)" (version 1 D/N Band) nighttime annual average radiance composite image data. We defined light pollution as artificial light brightness greater than 10% of the natural sky brightness above 45° of elevation (>1.14 × 10 -11 Wm -2 sr -1 ). We fitted a generalized linear model (GLM), a GLM with eigenvectors spatial filtering (GLM-ESF), and a generalized estimating equations (GEE) approach for each species to examine the potential correlation of nest density with light pollution. Our models are robust and reliable in terms of the ability to deal with data distribution and spatial autocorrelation (SA) issues violating model assumptions. All three models found that nest density is significantly negatively correlated with light pollution for each sea turtle species: the higher light pollution, the lower nest density. The two spatially extended models (GLM-ESF and GEE) show that light pollution influences nest density in a descending order from green turtles, to loggerheads, and then to leatherbacks. The research findings have an implication for sea turtle conservation policy and ordinance making. Near-coastal lights-out ordinances and other approaches to shield lights can protect sea turtles and their nests. The VIIRS DNB light data, having significant improvements over comparable data by its predecessor, the DMSP-OLS, shows promise for continued and improved research about ecological effects of artificial light pollution. Copyright © 2018 Elsevier Ltd. All rights reserved.

Predation as a landscape effect: the trading off by prey species between predation risks and protection benefits.

PubMed

Mönkkönen, M; Husby, M; Tornberg, R; Helle, P; Thomson, R L

2007-05-01

1. Predators impose costs on their prey but may also provide benefits such as protection against other (e.g. nest) predators. The optimal breeding location in relation to the distance from a nesting raptor varies so as to minimize the sum of costs of adult and nest predation. We provide a conceptual model to account for variation in the relative predation risks and derive qualitative predictions for how different prey species should respond to the distance from goshawk Accipiter gentilis nests. 2. We test the model predictions using a comprehensive collection of data from northern Finland and central Norway. First, we carried out a series of experiments with artificial bird nests to test if goshawks may provide protection against nest predation. Second, we conducted standard bird censuses and nest-box experiments to detect how the density or territory occupancy of several prey species varies with distance from the nearest goshawk nest. 3. Nest predation rate increased with distance from goshawk nest indicating that goshawks may provide protection for birds' nests against nest predation. Abundance (or probability of presence) of the main prey species of goshawks peaked at intermediate distances from goshawk nests, reflecting the trade-off. The abundance of small songbird species decreased with distance from goshawk nests. The goshawk poses little risk to small songbirds and they may benefit from goshawk proximity in protection against nest predation. Finally, no pattern with distance in pied flycatcher territory (nest box) occupation rate or the onset of egg-laying was detected. This is expected, as flycatchers neither suffer from marked nest predation risk nor are favoured goshawk prey. 4. Our results suggest that territory location in relation to the nest of a predator is a trade-off situation where adult birds weigh the risk of themselves being predated against the benefits accrued from increased nest survival. Prey species appear able to detect and measure alternative predation risks, and respond adaptively. From the prey perspective, the landscape is a mosaic of habitat patches the quality of which varies according to structural and floristic features, but also to the spatial distribution of predators.

Interactive effects between nest microclimate and nest vegetation structure confirm microclimate thresholds for Lesser Prairie-Chicken nest survival

USGS Publications Warehouse

Grisham, Blake A.; Godar, Alixandra J.; Boal, Clint W.; Haukos, David A.

2016-01-01

The range of Lesser Prairie-Chickens (Tympanuchus pallidicinctus) spans 4 unique ecoregions along 2 distinct environmental gradients. The Sand Shinnery Oak Prairie ecoregion of the Southern High Plains of New Mexico and Texas is environmentally isolated, warmer, and more arid than the Short-Grass, Sand Sagebrush, and Mixed-Grass Prairie ecoregions in Colorado, Kansas, Oklahoma, and the northeast panhandle of Texas. Weather is known to influence Lesser Prairie-Chicken nest survival in the Sand Shinnery Oak Prairie ecoregion; regional variation may also influence nest microclimate and, ultimately, survival during incubation. To address this question, we placed data loggers adjacent to nests during incubation to quantify temperature and humidity distribution functions in 3 ecoregions. We developed a suite of a priori nest survival models that incorporated derived microclimate parameters and visual obstruction as covariates in Program MARK. We monitored 49 nests in Mixed-Grass, 22 nests in Sand Shinnery Oak, and 30 nests in Short-Grass ecoregions from 2010 to 2014. Our findings indicated that (1) the Sand Shinnery Oak Prairie ecoregion was hotter and drier during incubation than the Mixed- and Short-Grass ecoregions; (2) nest microclimate varied among years within ecoregions; (3) visual obstruction was positively associated with nest survival; but (4) daily nest survival probability decreased by 10% every half-hour when temperature was greater than 34°C and vapor pressure deficit was less than −23 mmHg during the day (about 0600–2100 hours). Our major finding confirmed microclimate thresholds for nest survival under natural conditions across the species' distribution, although Lesser Prairie-Chickens are more likely to experience microclimate conditions that result in nest failures in the Sand Shinnery Oak Prairie ecoregion. The species would benefit from identification of thermal landscapes and management actions that promote cooler, more humid nest microclimates.

Breeding biology and nest-site selection of red-tailed hawks in an altered desert grassland

USGS Publications Warehouse

Hobbs, R.J.; DeStefano, S.; Halvorson, W.L.

2006-01-01

Red-tailed Hawks (Buteo jamaicensis) have expanded their range as trees have invaded formerly-open grasslands. Desert grasslands of southern Arizona have been invaded by mesquite trees (Prosopis velutina) since Anglo-American settlement and now support a large population of Red-tailed Hawks. We studied a population of Red-tailed Hawks in an altered desert grassland in southern Arizona. Our objectives were to determine what environmental characteristics influence Red-tailed Hawk habitat selection in mesquite-invaded desert grasslands and to evaluate the habitat quality of these grasslands for Red-tailed Hawks based on nesting density, nest success, and productivity. Red-tailed Hawks had 86% (95% C.I. = 73-99) nest success and 1.82 young per breeding pair (95% C.I. = 1.41-2.23). Nesting density was 0.15 (95% CI = 0.08-0.21) breeding pairs/km2 and the mean nearest-neighbor distance was 1.95 km (95% C.I. = 1.74-2.16). Red-tailed Hawks selected nest-sites with taller nest-trees and greater tree height and cover than were available at random. Mesquite trees in desert grasslands provide abundant potential nesting structures for Red-tailed Hawks. ?? 2006 The Raptor Research Foundation, Inc.

A review of the nest protection hypothesis: does inclusion of fresh green plant material in birds' nests reduce parasite infestation?

PubMed

Scott-Baumann, James F; Morgan, Eric R

2015-07-01

The use of aromatic plants and their essential oils for ectoparasite treatment is a field of growing interest. Several species of birds regularly introduce aromatic herbs into their nests putatively to reduce parasites. The behaviour is most often seen in cavity nesting birds and after nest building has finished. The plants are included in a non-structural manner and are often strongly aromatic. Various different hypotheses have been proposed regarding the function of this behaviour; from the plants altering some non-living factor in the nest (crypsis, water loss and insulation hypotheses) to them being involved in mate selection (mate hypothesis) or even having a beneficial effect, direct or indirect, on chicks (drug or nest protection hypothesis, NPH). Many studies have been carried out over the years observing and experimentally testing these hypotheses. This review focuses on studies involving the most popular of these hypotheses, the NPH: that plants decrease nest parasites or pathogens, thereby conveying positive effects to the chicks, allowing the behaviour to evolve. Studies providing observational evidence towards this hypothesis and those experimentally testing it are discussed.

Brief communication: why sleep in a nest? Empirical testing of the function of simple shelters made by wild chimpanzees.

PubMed

Stewart, F A

2011-10-01

All great apes build nightly a structure ("nest" or "bed") that is assumed to function primarily as a sleeping-platform. However, several other nest function hypotheses have been proposed: antipredation, antipathogen, and thermoregulation. I tested these simple shelter functions of chimpanzee nests in an experiment for which I was the subject in Fongoli, Senegal. I slept 11 nights in chimpanzee nests and on the bare ground to test for differences in sleep quality, potential exposure to disease through bites from possible vectors, and insulation. No difference was found in the total amount of sleep nor in sleep quality; however, sleep was more disturbed on the ground. Differences in sleep disturbance between arboreal and ground conditions seemed primarily due to causes of anxiety and alertness, e.g., vocalizations of terrestrial mammals. Arboreal nest-sleeping seems to reduce risk of bites from possible disease vectors and provide insulation in cold conditions. This preliminary, but direct, test of chimpanzee nest function has implications for the evolutionary transition from limb-roosting to nest-reclining sleep in the hominoids, and from tree-to-ground sleep in the genus Homo. Copyright © 2011 Wiley-Liss, Inc.

Multilevel and Single-Level Models for Measured and Latent Variables When Data Are Clustered

ERIC Educational Resources Information Center

Stapleton, Laura M.; McNeish, Daniel M.; Yang, Ji Seung

2016-01-01

Multilevel models are often used to evaluate hypotheses about relations among constructs when data are nested within clusters (Raudenbush & Bryk, 2002), although alternative approaches are available when analyzing nested data (Binder & Roberts, 2003; Sterba, 2009). The overarching goal of this article is to suggest when it is appropriate…

Processing multiple non-adjacent dependencies: evidence from sequence learning

PubMed Central

de Vries, Meinou H.; Petersson, Karl Magnus; Geukes, Sebastian; Zwitserlood, Pienie; Christiansen, Morten H.

2012-01-01

Processing non-adjacent dependencies is considered to be one of the hallmarks of human language. Assuming that sequence-learning tasks provide a useful way to tap natural-language-processing mechanisms, we cross-modally combined serial reaction time and artificial-grammar learning paradigms to investigate the processing of multiple nested (A1A2A3B3B2B1) and crossed dependencies (A1A2A3B1B2B3), containing either three or two dependencies. Both reaction times and prediction errors highlighted problems with processing the middle dependency in nested structures (A1A2A3B3_B1), reminiscent of the ‘missing-verb effect’ observed in English and French, but not with crossed structures (A1A2A3B1_B3). Prior linguistic experience did not play a major role: native speakers of German and Dutch—which permit nested and crossed dependencies, respectively—showed a similar pattern of results for sequences with three dependencies. As for sequences with two dependencies, reaction times and prediction errors were similar for both nested and crossed dependencies. The results suggest that constraints on the processing of multiple non-adjacent dependencies are determined by the specific ordering of the non-adjacent dependencies (i.e. nested or crossed), as well as the number of non-adjacent dependencies to be resolved (i.e. two or three). Furthermore, these constraints may not be specific to language but instead derive from limitations on structured sequence learning. PMID:22688641

Coordinating compass-based and nest-based flight directions during bumblebee learning and return flights.

PubMed

Collett, Thomas S; de Ibarra, Natalie Hempel; Riabinina, Olena; Philippides, Andrew

2013-03-15

Bumblebees tend to face their nest over a limited range of compass directions when learning the nest's location on departure and finding it on their approach after foraging. They thus obtain similar views of the nest and its surroundings on their learning and return flights. How do bees coordinate their flights relative to nest-based and compass-based reference frames to get such similar views? We show, first, that learning and return flights contain straight segments that are directed along particular compass bearings, which are independent of the orientation of a bee's body. Bees are thus free within limits to adjust their viewing direction relative to the nest, without disturbing flight direction. Second, we examine the coordination of nest-based and compass-based control during likely information gathering segments of these flights: loops during learning flights and zigzags on return flights. We find that bees tend to start a loop or zigzag when flying within a restricted range of compass directions and to fly towards the nest and face it after a fixed change in compass direction, without continuous interactions between their nest-based and compass-based directions of flight. A preferred trajectory of compass-based flight over the course of a motif, combined with the tendency of the bees to keep their body oriented towards the nest automatically narrows the range of compass directions over which bees view the nest. Additionally, the absence of interactions between the two reference frames allows loops and zigzags to have a stereotyped form that can generate informative visual feedback.

Movements and Habitat-Use of Loggerhead Sea Turtles in the Northern Gulf of Mexico during the Reproductive Period

PubMed Central

Hart, Kristen M.; Lamont, Margaret M.; Sartain, Autumn R.; Fujisaki, Ikuko; Stephens, Brail S.

2013-01-01

Nesting strategies and use of important in-water habitats for far-ranging marine turtles can be determined using satellite telemetry. Because of a lack of information on habitat-use by marine turtles in the northern Gulf of Mexico, we used satellite transmitters in 2010 through 2012 to track movements of 39 adult female breeding loggerhead turtles (Caretta caretta) tagged on nesting beaches at three sites in Florida and Alabama. During the nesting season, recaptured turtles emerged to nest 1 to 5 times, with mean distance between emergences of 27.5 km; however, several turtles nested on beaches separated by ∼250 km within a single season. Mean total distances traveled throughout inter-nesting periods for all turtles was 1422.0±930.8 km. In-water inter-nesting sites, delineated using 50% kernel density estimation (KDE), were located a mean distance of 33.0 km from land, in water with mean depth of −31.6 m; other in-water inter-nesting sites, delineated using minimum convex polygon (MCP) approach, were located a mean 13.8 km from land and in water with a mean depth of −15.8 m. Mean size of in-water inter-nesting habitats were 61.9 km2 (50% KDEs, n = 10) and 741.4 km2 (MCPs, n = 30); these areas overlapped significantly with trawling and oil and gas extraction activities. Abundance estimates for this nesting subpopulation may be inaccurate in light of how much spread there is between nests of the same individual. Further, our results also have consequences for critical habitat designations for northern Gulf loggerheads, as protection of one nesting beach would not encompass the entire range used by turtles during breeding seasons. PMID:23843971

Movements and habitat-use of loggerhead sea turtles in the northern Gulf of Mexico during the reproductive period

USGS Publications Warehouse

Hart, Kristen M.; Lamont, Margaret M.; Sartain-Iverson, Autumn R.; Fujisaki, Ikuko; Stephens, Brail S.

2013-01-01

Nesting strategies and use of important in-water habitats for far-ranging marine turtles can be determined using satellite telemetry. Because of a lack of information on habitat-use by marine turtles in the northern Gulf of Mexico, we used satellite transmitters in 2010 through 2012 to track movements of 39 adult female breeding loggerhead turtles (Caretta caretta) tagged on nesting beaches at three sites in Florida and Alabama. During the nesting season, recaptured turtles emerged to nest 1 to 5 times, with mean distance between emergences of 27.5 km; however, several turtles nested on beaches separated by ~250 km within a single season. Mean total distances traveled throughout inter-nesting periods for all turtles was 1422.0±930.8 km. In-water inter-nesting sites, delineated using 50% kernel density estimation (KDE), were located a mean distance of 33.0 km from land, in water with mean depth of −31.6 m; other in-water inter-nesting sites, delineated using minimum convex polygon (MCP) approach, were located a mean 13.8 km from land and in water with a mean depth of −15.8 m. Mean size of in-water inter-nesting habitats were 61.9 km2 (50% KDEs, n = 10) and 741.4 km2 (MCPs, n = 30); these areas overlapped significantly with trawling and oil and gas extraction activities. Abundance estimates for this nesting subpopulation may be inaccurate in light of how much spread there is between nests of the same individual. Further, our results also have consequences for critical habitat designations for northern Gulf loggerheads, as protection of one nesting beach would not encompass the entire range used by turtles during breeding seasons.

Movements and habitat-use of loggerhead sea turtles in the northern Gulf of Mexico during the reproductive period.

PubMed

Hart, Kristen M; Lamont, Margaret M; Sartain, Autumn R; Fujisaki, Ikuko; Stephens, Brail S

2013-01-01

Nesting strategies and use of important in-water habitats for far-ranging marine turtles can be determined using satellite telemetry. Because of a lack of information on habitat-use by marine turtles in the northern Gulf of Mexico, we used satellite transmitters in 2010 through 2012 to track movements of 39 adult female breeding loggerhead turtles (Caretta caretta) tagged on nesting beaches at three sites in Florida and Alabama. During the nesting season, recaptured turtles emerged to nest 1 to 5 times, with mean distance between emergences of 27.5 km; however, several turtles nested on beaches separated by ~250 km within a single season. Mean total distances traveled throughout inter-nesting periods for all turtles was 1422.0 ± 930.8 km. In-water inter-nesting sites, delineated using 50% kernel density estimation (KDE), were located a mean distance of 33.0 km from land, in water with mean depth of -31.6 m; other in-water inter-nesting sites, delineated using minimum convex polygon (MCP) approach, were located a mean 13.8 km from land and in water with a mean depth of -15.8 m. Mean size of in-water inter-nesting habitats were 61.9 km(2) (50% KDEs, n = 10) and 741.4 km(2) (MCPs, n = 30); these areas overlapped significantly with trawling and oil and gas extraction activities. Abundance estimates for this nesting subpopulation may be inaccurate in light of how much spread there is between nests of the same individual. Further, our results also have consequences for critical habitat designations for northern Gulf loggerheads, as protection of one nesting beach would not encompass the entire range used by turtles during breeding seasons.

Present and future thermal environments available to Sharp-tailed Grouse in an intact grassland.

PubMed

Raynor, Edward J; Powell, Larkin A; Schacht, Walter H

2018-01-01

Better understanding animal ecology in terms of thermal habitat use has become a focus of ecological studies, in large part due to the predicted temperature increases associated with global climate change. To further our knowledge on how ground-nesting endotherms respond to thermal landscapes, we examined the thermal ecology of Sharp-tailed Grouse (Tympanuchus phasianellus) during the nesting period. We measured site-specific iButton temperatures (TiB) and vegetation characteristics at nest sites, nearby random sites, and landscape sites to assess thermal patterns at scales relevant to nesting birds. We asked if microhabitat vegetation characteristics at nest sites matched the characteristics that directed macrohabitat nest-site selection. Grouse selected sites sheltered by dense vegetation for nesting that moderated TiB on average up to 2.7°C more than available landscape sites. Successful nests were positioned in a way that reduced exposure to thermal extremes by as much as 4°C relative to failed nests with an overall mean daytime difference (±SE) of 0.4 ±0.03°C. We found that macrohabitat nest-site selection was guided by dense vegetation cover and minimal bare ground as also seen at the microhabitat scale. Global climate projections for 2080 suggest that TiB at nest sites may approach temperatures currently avoided on the landscape, emphasizing a need for future conservation plans that acknowledge fine-scale thermal space in climate change scenarios. These data show that features of grassland landscapes can buffer organisms from unfavorable microclimatic conditions and highlight how thermal heterogeneity at the individual-level can drive decisions guiding nest site selection.

Present and future thermal environments available to Sharp-tailed Grouse in an intact grassland

PubMed Central

Powell, Larkin A.; Schacht, Walter H.

2018-01-01

Better understanding animal ecology in terms of thermal habitat use has become a focus of ecological studies, in large part due to the predicted temperature increases associated with global climate change. To further our knowledge on how ground-nesting endotherms respond to thermal landscapes, we examined the thermal ecology of Sharp-tailed Grouse (Tympanuchus phasianellus) during the nesting period. We measured site-specific iButton temperatures (TiB) and vegetation characteristics at nest sites, nearby random sites, and landscape sites to assess thermal patterns at scales relevant to nesting birds. We asked if microhabitat vegetation characteristics at nest sites matched the characteristics that directed macrohabitat nest-site selection. Grouse selected sites sheltered by dense vegetation for nesting that moderated TiB on average up to 2.7°C more than available landscape sites. Successful nests were positioned in a way that reduced exposure to thermal extremes by as much as 4°C relative to failed nests with an overall mean daytime difference (±SE) of 0.4 ±0.03°C. We found that macrohabitat nest-site selection was guided by dense vegetation cover and minimal bare ground as also seen at the microhabitat scale. Global climate projections for 2080 suggest that TiB at nest sites may approach temperatures currently avoided on the landscape, emphasizing a need for future conservation plans that acknowledge fine-scale thermal space in climate change scenarios. These data show that features of grassland landscapes can buffer organisms from unfavorable microclimatic conditions and highlight how thermal heterogeneity at the individual-level can drive decisions guiding nest site selection. PMID:29415080

Population-specific demographic estimates provide insights into declines of Lark Buntings (Calamospiza melanocorys)

USGS Publications Warehouse

Yackel Adams, A.A.; Skagen, S.K.; Savidge, J.A.

2007-01-01

Many North American prairie bird populations have recently declined, and the causes of these declines remain largely unknown. To determine whether population limitation occurs during breeding, we evaluated the stability of a population of prairie birds using population-specific values for fecundity and postfledging survival. During 2001-2003, we radiomarked 67 female Lark Buntings (Calamospiza melanocorys) to determine annual fecundity and evaluate contributing factors such as nest survival and breeding response (number of breeding attempts and dispersal). Collectively, 67 females built 112 nests (1.67 ± 0.07 nests female−1 season−1; range: 1–3); 34 were second nests and 11 were third nests. Daily nest survival estimates were similar for initial and later nests with overall nest survival (DSR19) of 30.7% and 31.7%, respectively. Nest predation was the most common cause of failure (92%). Capture and radiomarking of females did not affect nest survival. Lark Bunting dispersal probabilities increased among females that fledged young from initial nests and females that lost their original nests late in the season. Conservative and liberal estimates of mean annual fecundity were 0.96 ±0.11 and 1.24 ± 0.09 female offspring per female, respectively. Given the fecundity and juvenile-survival estimates for this population, annual adult survival values of 71–77% are necessary to achieve a stable population. Because adult survival of prairie passerines ranges between 55% and 65%, this study area may not be capable of sustaining a stable population in the absence of immigration. We contrast our population assessment with one that assumes indirect values of fecundity and juvenile survival. To elucidate limiting factors, estimation of population-specific demographic parameters is desirable. We present an approach for selecting species and areas for evaluation of population stability.

Modeling marbled murrelet (Brachyramphus marmoratus) habitat using LiDAR-derived canopy data

USGS Publications Warehouse

Hagar, Joan C.; Eskelson, Bianca N.I.; Haggerty, Patricia K.; Nelson, S. Kim; Vesely, David G.

2014-01-01

LiDAR (Light Detection And Ranging) is an emerging remote-sensing tool that can provide fine-scale data describing vertical complexity of vegetation relevant to species that are responsive to forest structure. We used LiDAR data to estimate occupancy probability for the federally threatened marbled murrelet (Brachyramphus marmoratus) in the Oregon Coast Range of the United States. Our goal was to address the need identified in the Recovery Plan for a more accurate estimate of the availability of nesting habitat by developing occupancy maps based on refined measures of nest-strand structure. We used murrelet occupancy data collected by the Bureau of Land Management Coos Bay District, and canopy metrics calculated from discrete return airborne LiDAR data, to fit a logistic regression model predicting the probability of occupancy. Our final model for stand-level occupancy included distance to coast, and 5 LiDAR-derived variables describing canopy structure. With an area under the curve value (AUC) of 0.74, this model had acceptable discrimination and fair agreement (Cohen's κ = 0.24), especially considering that all sites in our sample were regarded by managers as potential habitat. The LiDAR model provided better discrimination between occupied and unoccupied sites than did a model using variables derived from Gradient Nearest Neighbor maps that were previously reported as important predictors of murrelet occupancy (AUC = 0.64, κ = 0.12). We also evaluated LiDAR metrics at 11 known murrelet nest sites. Two LiDAR-derived variables accurately discriminated nest sites from random sites (average AUC = 0.91). LiDAR provided a means of quantifying 3-dimensional canopy structure with variables that are ecologically relevant to murrelet nesting habitat, and have not been as accurately quantified by other mensuration methods.

Influence of fine-scale habitat structure on nest-site occupancy, laying date and clutch size in Blue Tits Cyanistes caeruleus

NASA Astrophysics Data System (ADS)

Amininasab, Seyed Mehdi; Vedder, Oscar; Schut, Elske; de Jong, Berber; Magrath, Michael J. L.; Korsten, Peter; Komdeur, Jan

2016-01-01

Most birds have specific habitat requirements for breeding. The vegetation structure surrounding nest-sites is an important component of habitat quality, and can have large effects on avian breeding performance. We studied 13 years of Blue Tit Cyanistes caeruleus population data to determine whether characteristics of vegetation structure predict site occupancy, laying date and number of eggs laid. Measurements of vegetation structure included the density of English Oak Quercus robur, European Beech Fagus sylvatica, and other deciduous, coniferous and non-coniferous evergreen trees, within a 20-m radius of nest-boxes used for breeding. Trees were further sub-divided into specific classes of trunk circumferences to determine the densities for different maturity levels. Based on Principal Component Analysis (PCA), we reduced the total number of 17 measured vegetation variables to 7 main categories, which we used for further analyses. We found that the occupancy rate of sites and the number of eggs laid correlated positively with the proportion of deciduous trees and negatively with the density of coniferous trees. Laying of the first egg was advanced with a greater proportion of deciduous trees. Among deciduous trees, the English Oak appeared to be most important, as a higher density of more mature English Oak trees was associated with more frequent nest-box occupancy, a larger number of eggs laid, and an earlier laying start. Furthermore, laying started earlier and more eggs were laid in nest-boxes with higher occupancy rates. Together, these findings highlight the role of deciduous trees, particularly more mature English Oak, as important predictors of high-quality preferred habitat. These results aid in defining habitat quality and will facilitate future studies on the importance of environmental quality for breeding performance.

On a useful functional representation of control system structure

NASA Technical Reports Server (NTRS)

Malchow, Harvey L.

1988-01-01

An alternative structure for control systems is proposed. The structure is represented by a three-element block diagram and three functional definitions. It is argued that the three functional elements form a canonical set. The set includes the functions description, estimation and control. General overlay of the structure on parallel state and nested-state control systems is discussed. Breakdown of two real nested-state control systems into the proposed functional format is displayed. Application of the process to the mapping of complex control systems R and D efforts is explained with the Mars Rover Sample and Return mission as an example. A previous application of this basic functional structure to Space Station performance requirements organization is discussed.

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.

Polydomy in the ant Ectatomma opaciventre

PubMed Central

Tofolo, Viviane C.; Giannotti, Edilberto; Neves, Erika F.; Andrade, Luis H. C.; M. Lima, Sandro; Súarez, Yzel R.; Antonialli-Junior, William F.

2014-01-01

Abstract Tropical ants commonly exhibit a hyper-dispersed pattern of spatial distribution of nests. In polydomous species, nests may be satellites, that is, secondary structures of the main nest, where the queen is found. In order to evaluate whether the ant Ectatomma opaciventre Roger (Formicidae: Ectatomminae) uses the strategy of building polydomous nests, the spatial distribution pattern of 33 nests in a 1,800 m 2 degraded area located in Rio Claro, SP, Brazil, were investigated using the nearest neighbor method. To complement the results of this investigation, the cuticular chemical profile of eight colonies was analyzed using Fourier transform infrared photoacoustic spectrosco-py (FTIR-PAS). The nests of E. opaciventre presented a hyper-dispersed or regular distribution, which is the most common in ants. The analysis of the cuticular hydrocarbons apparently con-firmed the hypothesis that this species is polydomous, since the chemical profiles of all studied colonies with nests at different sites were very similar to the chemical signature of the single found queen and were also different from those of colonies used as control. PMID:25373168

Timing of spring wild turkey hunting in relation to nest incubation

USGS Publications Warehouse

Casalena, Mary Jo; Everett, Rex; Vreeland, Wendy C.; Gregg, Ian D.; Diefenbach, Duane R.

2016-01-01

State wildlife agencies are often requested to open spring wild turkey (Meleagris gallopavo; hereafter, turkey) hunting seasons earlier to increase hunter satisfaction by hunters hearing more gobbling male turkeys. Timing of spring turkey hunting season in several states, including Pennsylvania, has been established to open, on average, near median date of incubation initiation of turkey nests. This is believed to reduce illegal and undesired hen harvest and possibly nest abandonment, while maintaining hunter satisfaction of hearing male turkeys when most hens are incubating eggs. However, Pennsylvania’s spring season structure was established in 1968. Given earlier spring phenology, and potentially more variation in spring weather due to climate change, there is concern that timing of nest incubation for turkeys in Pennsylvania could be changing. Therefore, our objective was to determine if nest incubation and opening of spring turkey hunting in Pennsylvania have continued to coincide. We attached satellite transmitters to 254 female turkeys during 2010–2014 and estimated median incubation initiation date to be 2 May, which was 2 days earlier than median date during a statewide study during 1953–1963 and 9 days earlier than during a smaller scale study in south–central Pennsylvania during 2000–2001. However, incubation initiation varied greatly among years and individual hens during all 3 studies. During 4 of 5 years of our study, Pennsylvania’s spring season opened 3 to 8 days prior to median date of incubation initiation. Over the 5 years, estimated initiation of incubation for first nesting attempts, measured from earliest date of incubation initiation to latest, was >2 months and maximum proportion of hens beginning incubation at any one time differed by several days to >1 week. Consequently, in years of late incubation, a constant season opening date set near the long-term median date of incubation initiation exposes few additional hens to risk and hunter satisfaction is likely maintained at greater levels than would be seen with a more conservative approach of opening the season later. Long-term and large scale studies using GPS transmitters that provide precise determination of incubation initiation will be useful to study environmental influences on initiation of incubation.

Landmark memories are more robust when acquired at the nest site than en route: experiments in desert ants.

PubMed

Bisch-Knaden, Sonja; Wehner, Rüdiger

2003-03-01

Foraging desert ants, Cataglyphis fortis, encounter different sequences of visual landmarks while navigating by path integration. This paper explores the question whether the storage of landmark information depends on the context in which the landmarks are learned during an ant's foraging journey. Two experimental set-ups were designed in which the ants experienced an artificial landmark panorama that was placed either around the nest entrance (nest marks) or along the vector route leading straight towards the feeder (route marks). The two training paradigms resulted in pronounced differences in the storage characteristics of the acquired landmark information: memory traces of nest marks were much more robust against extinction and/or suppression than those of route marks. In functional terms, this result is in accord with the observation that desert ants encounter new route marks during every foraging run but always pass the same landmarks when approaching the nest entrance.

Nest-Gallery Development and Caste Composition of Isolated Foraging Groups of the Drywood Termite, Incisitermes minor (Isoptera: Kalotermitidae)

PubMed Central

Himmi, S. Khoirul; Yoshimura, Tsuyoshi; Yanase, Yoshiyuki; Oya, Masao; Torigoe, Toshiyuki; Akada, Masanori; Imadzu, Setsuo

2016-01-01

An X-ray computed-tomographic examination of nest-gallery development from timbers naturally infested by foraging groups of Incisitermes minor colonies was conducted. This study documents the colonization process of I. minor to new timbers and how the isolated groups maintain their nest-gallery system. The results suggested that development of a nest-gallery within a suitable wood item is not random, but shows selection for softer substrate and other adaptations to the different timber environments. Stigmergic coordinations were expressed in dynamic changes of the nest-gallery system; indicated by fortification behavior in sealing and re-opening a tunnel approaching the outer edge of the timber, and accumulating fecal pellets in particular chambers located beneath the timber surface. The study also examines the caste composition of isolated groups to discover how I. minor sustains colonies with and without primary reproductives. PMID:27455332

Phenotypic assessments of peanut nested association mapping (NAM) populations

USDA-ARS?s Scientific Manuscript database

Nested association mapping (NAM) is a valuable innovation and multi-parental mapping population strategy in peanut genetics which increases the power to map quantitative trait loci and assists in extending the gene pool of elite peanut lines. In the peanut research community, two structured mapping ...

Smartphone technologies and Bayesian networks to assess shorebird habitat selection

USGS Publications Warehouse

Zeigler, Sara; Thieler, E. Robert; Gutierrez, Ben; Plant, Nathaniel G.; Hines, Megan K.; Fraser, James D.; Catlin, Daniel H.; Karpanty, Sarah M.

2017-01-01

Understanding patterns of habitat selection across a species’ geographic distribution can be critical for adequately managing populations and planning for habitat loss and related threats. However, studies of habitat selection can be time consuming and expensive over broad spatial scales, and a lack of standardized monitoring targets or methods can impede the generalization of site-based studies. Our objective was to collaborate with natural resource managers to define available nesting habitat for piping plovers (Charadrius melodus) throughout their U.S. Atlantic coast distribution from Maine to North Carolina, with a goal of providing science that could inform habitat management in response to sea-level rise. We characterized a data collection and analysis approach as being effective if it provided low-cost collection of standardized habitat-selection data across the species’ breeding range within 1–2 nesting seasons and accurate nesting location predictions. In the method developed, >30 managers and conservation practitioners from government agencies and private organizations used a smartphone application, “iPlover,” to collect data on landcover characteristics at piping plover nest locations and random points on 83 beaches and barrier islands in 2014 and 2015. We analyzed these data with a Bayesian network that predicted the probability a specific combination of landcover variables would be associated with a nesting site. Although we focused on a shorebird, our approach can be modified for other taxa. Results showed that the Bayesian network performed well in predicting habitat availability and confirmed predicted habitat preferences across the Atlantic coast breeding range of the piping plover. We used the Bayesian network to map areas with a high probability of containing nesting habitat on the Rockaway Peninsula in New York, USA, as an example application. Our approach facilitated the collation of evidence-based information on habitat selection from many locations and sources, which can be used in management and decision-making applications.

Sparrow nest survival in relation to prescribed fire and woody plant invasion in a northern mixed-grass prairie

USGS Publications Warehouse

Murphy, Robert K.; Shaffer, Terry L.; Grant, Todd A.; Derrig, James L.; Rubin, Cory S.; Kerns, Courtney K.

2017-01-01

Prescribed fire is used to reverse invasion by woody vegetation on grasslands, but managers often are uncertain whether influences of shrub and tree reduction outweigh potential effects of fire on nest survival of grassland birds. During the 2001–2003 breeding seasons, we examined relationships of prescribed fire and woody vegetation to nest survival of clay-colored sparrow (Spizella pallida) and Savannah sparrow (Passerculus sandwichensis) in mixed-grass prairie at Des Lacs National Wildlife Refuge in northwestern North Dakota, USA. We assessed relationships of nest survival to 1) recent fire history, in terms of number of breeding seasons (2, 3, or 4–5) since the last prescribed fire, and 2) prevalence of trees and tall (>1.5 m) shrubs in the landscape and of low (≤1.5 m) shrubs within 5 m of nests. Nest survival of both species exhibited distinct patterns related to age of the nest and day of year, but bore no relationship to fire history. Survival of clay-colored sparrow nests declined as the amount of trees and tall shrubs within 100 m increased, but we found no relationship to suggest nest parasitism by brown-headed cowbirds (Molothrus ater) as an underlying mechanism. We found little evidence linking nest survival of Savannah sparrow to woody vegetation. Our results suggest that fire can be used to restore northern mixed-grass prairies without adversely affecting nest survival of ≥2 widespread passerine species. Survival of nests of clay-colored sparrow may increase when tall woody cover is reduced by fire. Our data lend support to the use of fire for reducing scattered patches of tall woody cover to enhance survival of nests of ≥1 grassland bird species in northern mixed-grass prairies, but further study is needed that incorporates experimental approaches and assessments of shorter term effects of fire on survival of nests of grassland passerines.

What do giant titanosaur dinosaurs and modern Australasian megapodes have in common?

PubMed Central

Grellet-Tinner, Gerald; Fiorelli, Lucas E.

2015-01-01

Titanosauria is a globally distributed clade of sometimes extremely large Mesozoic herbivorous sauropod dinosaurs. On the basis of current evidence these giant dinosaurs seem to have reproduced in specific and localized nesting sites. However, no investigations have been performed to understand the possible ecological and geological biases that acted for the selection of these nesting sites worldwide. In this study, observations were performed on the best-known Cretaceous nesting sites around the world. Our observations strongly suggest their eggs were incubated with environmental sources of heat, in burial conditions. Taking into account the clutch composition and geometry, the nature and properties of the sediments, the eggshells’ structures and conductance, it would appear that titanosaurs adopted nesting behaviors comparable to the modern Australasian megapodes, using burrow-nesting in diverse media and mound-building strategies. PMID:26623184

Nesting habitat relationships of sympatric Crested Caracaras, Red-tailed Hawks, and White-tailed Hawks in South Texas

USGS Publications Warehouse

Actkinson, M.A.; Kuvlesky, W.P.; Boal, C.W.; Brennan, L.A.; Hernandez, F.

2007-01-01

We quantified nesting-site habitats for sympatric White-tailed Hawks (Buteo albicaudatus) (n = 40), Red-tailed Hawks (B. jamaicensis) (n = 39), and Crested Caracaras (Caracara cheriway) (n = 24) in the Coastal Sand Plain of south Texas. White-tailed Hawks and Crested Caracara nest sites occurred in savannas, whereas Red-tailed Hawk nest sites occurred in woodlands on the edge of savannas. White-tailed Hawk nest sites were in shrubs and trees that were shorter (3.5 ?? 1.0 m) and had smaller canopy diameters (5.5 ?? 2.1 m) than those of Red-tailed Hawks (10.1 ?? 2.0 m, 13.7 ?? 5.8 m) and Crested Caracaras (5.6 ?? 1.7 m, 8.5 ?? 3.5 m). Red-tailed Hawk nest sites had higher woody densities (15.7 ?? 9.6 plants) and more woody cover (84 ?? 19%) than those of White-tailed Hawks (5.6 ?? 5.8 plants, 20 ?? 21%) and Crested Caracaras (9.9 ?? 6.7 plants, 55 ?? 34%). Crested Caracara nest sites were in dense, multi-branched shrubs composed of more living material (97 ?? 3%) than those of White-tailed (88 ?? 18%) and Red-tailed hawks (88 ?? 18%). Nest sites of White-tailed Hawks, Red-tailed Hawks, and Crested Caracaras were similar to random samples from the surrounding habitat indicating that preferred nesting habitat was available for each of these species at least within 60 m of active nest sites. Nest tree height, along with woody plant and native grass cover best discriminated nest sites among the three raptor species. There was no overlap at Red-tailed and White-tailed hawk nest sites in vegetation structure, while Crested Caracara nests were in habitat intermediate between the two other species. Partitioning of nesting habitat may be how these raptor species co-exist at the broader landscape scale of our study area in the Coastal Sand Plain of Texas.

Genetic Architecture of Nest Building in Mice LG/J × SM/J

PubMed Central

Sauce, Bruno; de Brito, Reinaldo Alves; Peripato, Andrea Cristina

2012-01-01

Maternal care is critical to offspring growth and survival, which is greatly improved by building an effective nest. Some suggest that genetic variation and underlying genetic effects differ between fitness-related traits and other phenotypes. We investigated the genetic architecture of a fitness-related trait, nest building, in F2 female mice intercrossed from inbred strains SM/J and LG/J using a QTL analysis for six related nest phenotypes (Presence and Structure pre- and postpartum, prepartum Material Used and postpartum Temperature). We found 15 direct-effect QTLs explaining from 4 to 13% of the phenotypic variation in nest building, mostly with non-additive effect. Epistatic analyses revealed 71 significant epistatic interactions which together explain from 28.4 to 75.5% of the variation, indicating an important role for epistasis in the adaptive process of nest building behavior in mice. Our results suggest a genetic architecture with small direct effects and a larger number of epistatic interactions as expected for fitness-related phenotypes. PMID:22654894

ELF communications system ecological monitoring program: Pollinating insect studies

NASA Astrophysics Data System (ADS)

Strickler, Karen; Schriber, J. Mark

1994-11-01

High voltage transmission lines and the earth's and other magnetic fields have been shown to affect honeybee reproduction, survival, orientation, and nest structure. ELY EM fields could have similar effects on native megachilid bees. Two species in the genus Megachile were abundant in artificial nests at experimental and control areas in Dickinson and Iron Counties in Michigan. Data on their nest architecture, nest activity, and emergence/mortality were collected between 1983 and 1993. Eight hypotheses concerning the possible effects of ELY EM fields were considered using these data. The ELY antenna has been fully operational since the summer of 1989. Tests of the hypotheses compare control vs. experimental areas before and after the ELY antenna became fully operational.

Evaluating Great Lakes bald eagle nesting habitat with Bayesian inference

Treesearch

Teryl G. Grubb; William W. Bowerman; Allen J. Bath; John P. Giesy; D. V. Chip Weseloh

2003-01-01

Bayesian inference facilitated structured interpretation of a nonreplicated, experience-based survey of potential nesting habitat for bald eagles (Haliaeetus leucocephalus) along the five Great Lakes shorelines. We developed a pattern recognition (PATREC) model of our aerial search image with six habitat attributes: (a) tree cover, (b) proximity and...

Design of the STAR-X Telescope

NASA Technical Reports Server (NTRS)

Saha, Timo T.; Zhang, William W.; McClelland, Ryan S.

2017-01-01

Top-level science goals of the Survey and Time-domain Astrophysical Research eXplorer (STAR-X) include: investigations of most violent explosions in the universe, study of growth of black holes across cosmic time and mass scale, and measure how structure formation heats majority of baryons in the universe. To meet these goals, the field-of-view of the telescope should be about 1 square-degree, the angular resolution should be 5 arc-seconds or below across large part of the field-of-view. The on-axis effective area at 1 KeV should be about 2,000 sq cm. Payload cost and launch considerations limit the outer diameter, focal length, and mass to 1.3 meters, 5 meters, and 250 kilograms, respectively. Telescope design is based on a segmented meta-shell approach we have developed at Goddard Space Flight Center for the STAR-X telescope. The telescope shells are divided into 30-degree segments. Individual telescopes and meta-shells are nested inside each other to meet the effective area requirements in 0.5 - 6.0 KeV range. We consider Wolter-Schwarzschild, and Modified-Wolter-Schwarzschild telescope designs as basic building blocks of the nested STAR-X telescope. These designs offer an excellent resolution over a large field of views. Nested telescopes are vulnerable to stray light problems. We have designed a multi-component baffle system to eliminate direct and single-reflection light paths inside the telescopes. Large number of internal and external baffle vane structures are required to prevent stray rays from reaching the focal plane. We have developed a simple ray-trace based tool to determine the dimensions and locations of the baffles. In this paper, we present the results of our trade studies, baffle design studies, and optical performance analyses of the STAR-X telescope.

Optical Design of the STAR-X Telescope

NASA Technical Reports Server (NTRS)

Saha, Timo T.; Zhang, William W.; McClelland, Ryan S.

2017-01-01

Top-level science goals of the Survey and Time-domain Astrophysical Research eXplorer (STAR-X) include: investigations of most violent explosions in the universe, study of growth of black holes across cosmic time and mass scale, and measure how structure formation heats majority of baryons in the universe. To meet these goals, the field-of-view of the telescope should be about 1 square-degree, the angular resolution should be 5 arc-seconds or below across large part of the field-of-view. The on-axis effective area at 1 KeV should be about 2,000 sq cm. Payload cost and launch considerations limit the outer diameter, focal length, and mass to 1.3 meters, 5 meters, and 250 kilograms, respectively. Telescope design is based on a segmented meta-shell approach we have developed at Goddard Space Flight Center for the STAR-X telescope. The telescope shells are divided into 30-degree segments. Individual telescopes and meta-shells are nested inside each other to meet the effective area requirements in 0.5 - 6.0 KeV range. We consider Wolter-Schwarzschild, and Modified-Wolter-Schwarzschild telescope designs as basic building blocks of the nested STAR-X telescope. These designs offer an excellent resolution over a large field of views. Nested telescopes are vulnerable to stray light problems. We have designed a multi-component baffle system to eliminate direct and single-reflection light paths inside the telescopes. Large number of internal and external baffle vane structures are required to prevent stray rays from reaching the focal plane. We have developed a simple ray-trace based tool to determine the dimensions and locations of the baffles. In this paper, we present the results of our trade studies, baffle design studies, and optical performance analyses of the STAR-X telescope.

A nested real-time PCR assay for the quantification of Plasmodium falciparum DNA extracted from dried blood spots.

PubMed

Tran, Tuan M; Aghili, Amirali; Li, Shanping; Ongoiba, Aissata; Kayentao, Kassoum; Doumbo, Safiatou; Traore, Boubacar; Crompton, Peter D

2014-10-04

As public health efforts seek to eradicate malaria, there has been an emphasis on eliminating low-density parasite reservoirs in asymptomatic carriers. As such, diagnosing submicroscopic Plasmodium infections using PCR-based techniques has become important not only in clinical trials of malaria vaccines and therapeutics, but also in active malaria surveillance campaigns. However, PCR-based quantitative assays that rely on nucleic acid extracted from dried blood spots (DBS) have demonstrated lower sensitivity than assays that use cryopreserved whole blood as source material. The density of Plasmodium falciparum asexual parasites was quantified using genomic DNA extracted from dried blood spots (DBS) and the sensitivity of two approaches was compared: quantitative real-time PCR (qPCR) targeting the P. falciparum 18S ribosomal RNA gene, either with an initial conventional PCR amplification prior to qPCR (nested qPCR), or without an initial amplification (qPCR only). Parasite densities determined by nested qPCR, qPCR only, and light microscopy were compared. Nested qPCR results in 10-fold higher sensitivity (0.5 parasites/μl) when compared to qPCR only (five parasites/ul). Among microscopy-positive samples, parasite densities calculated by nested qPCR correlated strongly with microscopy for both asymptomatic (Pearson's r=0.58, P<0.001) and symptomatic (Pearson's r=0.70, P<0.0001) P. falciparum infections. Nested qPCR improves the sensitivity for the detection of P. falciparum blood-stage infection from clinical DBS samples. This approach may be useful for active malaria surveillance in areas where submicroscopic asymptomatic infections are prevalent.

WRF nested large-eddy simulations of deep convection during SEAC4RS

NASA Astrophysics Data System (ADS)

Heath, Nicholas K.; Fuelberg, Henry E.; Tanelli, Simone; Turk, F. Joseph; Lawson, R. Paul; Woods, Sarah; Freeman, Sean

2017-04-01

Large-eddy simulations (LES) and observations are often combined to increase our understanding and improve the simulation of deep convection. This study evaluates a nested LES method that uses the Weather Research and Forecasting (WRF) model and, specifically, tests whether the nested LES approach is useful for studying deep convection during a real-world case. The method was applied on 2 September 2013, a day of continental convection that occurred during the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) campaign. Mesoscale WRF output (1.35 km grid length) was used to drive a nested LES with 450 m grid spacing, which then drove a 150 m domain. Results reveal that the 450 m nested LES reasonably simulates observed reflectivity distributions and aircraft-observed in-cloud vertical velocities during the study period. However, when examining convective updrafts, reducing the grid spacing to 150 m worsened results. We find that the simulated updrafts in the 150 m run become too diluted by entrainment, thereby generating updrafts that are weaker than observed. Lastly, the 450 m simulation is combined with observations to study the processes forcing strong midlevel cloud/updraft edge downdrafts that were observed on 2 September. Results suggest that these strong downdrafts are forced by evaporative cooling due to mixing and by perturbation pressure forces acting to restore mass continuity around neighboring updrafts. We conclude that the WRF nested LES approach, with further development and evaluation, could potentially provide an effective method for studying deep convection in real-world cases.

Species-specific differences in the fine structure of learning walk elements in Cataglyphis ants.

PubMed

Fleischmann, Pauline N; Grob, Robin; Wehner, Rüdiger; Rössler, Wolfgang

2017-07-01

Cataglyphis desert ants are famous navigators. Like all central place foragers, they are confronted with the challenge to return home, i.e. relocate an inconspicuous nest entrance in the ground, after their extensive foraging trips. When leaving the underground nest for the first time, desert ants perform a striking behavior, so-called learning walks that are well structured. However, it is still unclear how the ants initially acquire the information needed for sky- and landmark-based navigation, in particular how they calibrate their compass system at the beginning of their foraging careers. Using high-speed video analyses, we show that different Cataglyphis species include different types of characteristic turns in their learning walks. Pirouettes are full or partial rotations (tight turns about the vertical body axis) during which the ants frequently stop and gaze back in the direction of the nest entrance during the longest stopping phases. In contrast, voltes are small walked circles without directed stopping phases. Interestingly, only Cataglyphis ant species living in a cluttered, and therefore visually rich, environment (i.e. C. noda and C. aenescens in southern Greece) perform both voltes and pirouettes. They look back to the nest entrance during pirouettes, most probably to take snapshots of the surroundings. In contrast, C. fortis inhabiting featureless saltpans in Tunisia perform only voltes and do not stop during these turns to gaze back at the nest - even if a set of artificial landmarks surrounds the nest entrance. © 2017. Published by The Company of Biologists Ltd.

A Nested Analysis for Data Collected from Groups: Making Crowding Research More Efficient

ERIC Educational Resources Information Center

Schiffenbauer, Allen; And Others

1978-01-01

This paper examines the difference between dependent and independent responses and suggest that, for the case of independence, a nested analysis of variance model is appropriate. The advantages of this analytic approach are explained, and conditions are discussed under which more powerful test of treatment effects may be obtained. (Author/MA)

Marbled murrelet effectiveness monitoring plan for the Northwest Forest Plan.

Treesearch

Sarah Madsen; Diane Evans; Thomas Hamer; Paul Henson; Sherri Miller; S. Kim Nelson; Daniel Roby; Martin Stapanian

1999-01-01

This report describes options for effectiveness monitoring of long-term status and trends to evaluate the success of the Northwest Forest Plan in maintaining and restoring marbled murrelet nesting habitat and populations on Federal lands. A two-phase approach is described that begins with developing reliable and repeatable processes for identifying nesting habitat and...

Wired: impacts of increasing power line use by a growing bird population

NASA Astrophysics Data System (ADS)

Moreira, Francisco; Encarnação, Vitor; Rosa, Gonçalo; Gilbert, Nathalie; Infante, Samuel; Costa, Julieta; D'Amico, Marcello; Martins, Ricardo C.; Catry, Inês

2017-02-01

Power lines are increasingly widespread across many regions of the planet. Although these linear infrastructures are known for their negative impacts on bird populations, through collision and electrocution, some species take advantage of electricity pylons for nesting. In this case, estimation of the net impact of these infrastructures at the population level requires an assessment of trade-offs between positive and negative impacts. We compiled historical information (1958-2014) of the Portuguese white stork Ciconia ciconia population to analyze long-term changes in numbers, distribution range and use of nesting structures. White stork population size increased 660% up to 12000 breeding pairs between 1984 and 2014. In the same period, the proportion of nests on electricity pylons increased from 1% to 25%, likely facilitated by the 60% increase in the length of the very high tension power line grid (holding the majority of the nests) in the stork’s distribution range. No differences in breeding success were registered for storks nesting on electricity pylons versus other structures, but a high risk of mortality by collision and electrocution with power lines was estimated. We discuss the implications of this behavioral change, and of the management responses by power line companies, both for stork populations and for managers.

Lack of spatial genetic structure among nesting and wintering King Eiders

USGS Publications Warehouse

Pearce, J.M.; Talbot, S.L.; Pierson, Barbara J.; Petersen, M.R.; Scribner, K.T.; Dickson, D.L.; Mosbech, A.

2004-01-01

The King Eider (Somateria spectabilis) has been delineated into two broadly distributed breeding populations in North America (the western and eastern Arctic) on the basis of banding data and their use of widely separated Pacific and Atlantic wintering areas. Little is known about the level of gene flow between these two populations. Also unknown is whether behavioral patterns common among migratory waterfowl, such as site fidelity to wintering areas and pair formation at these sites, have existed for sufficient time to create a population structure defined by philopatry to wintering rather than to nesting locations. We used six nuclear microsatellite DNA loci and cytochrome b mitochondrial DNA sequence data to estimate the extent of spatial genetic differentiation among nesting and wintering areas of King Eiders across North America and adjacent regions. Estimates of interpopulation variance in microsatellite allele and mtDNA haplotype frequency were both low and nonsignificant based on samples from three wintering and four nesting areas. Results from nested clade analysis, mismatch distributions, and coalescent-based analyses suggest historical population growth and gene flow that collectively may have homogenized gene frequencies. The presence of several unique mtDNA haplotypes among birds wintering near Greenland suggests that gene flow may now be more limited between the western and eastern Arctic, which is consistent with banding data.

Influences of Species Interactions With Aggressive Ants and Habitat Filtering on Nest Colonization and Community Composition of Arboreal Twig-Nesting Ants.

PubMed

Philpott, Stacy M; Serber, Zachary; De la Mora, Aldo

2018-04-05

Ant community assembly is driven by many factors including species interactions (e.g., competition, predation, parasitism), habitat filtering (e.g., vegetation differences, microclimate, food and nesting resources), and dispersal. Canopy ant communities, including dominant and twig-nesting ants, are structured by all these different factors, but we know less about the impacts of species interactions and habitat filters acting at the colonization or recruitment stage. We examined occupation of artificial twig nests placed in shade trees in coffee agroecosystems. We asked whether species interactions-aggression from the dominant canopy ant, Azteca sericeasur Longino (Hymenoptera: Formicidae)-or habitat filtering-species of tree where nests were placed or surrounding vegetation-influence colonization, species richness, and community composition of twig-nesting ants. We found 20 species of ants occupying artificial nests. Nest occupation was lower on trees with A. sericeasur, but did not differ depending on tree species or surrounding vegetation. Yet, there were species-specific differences in occupation depending on A. sericeasur presence and tree species. Ant species richness did not vary with A. sericeasur presence or tree species. Community composition varied with A. sericeasur presence and surrounding vegetation. Our results suggest that species interactions with dominant ants are important determinants of colonization and community composition of twig-nesting ants. Habitat filtering at the level of tree species did not have strong effects on twig-nesting ants, but changes in coffee management may contribute to differences in community composition with important implications for ant conservation in agricultural landscapes, as well as biological control of coffee pests.

Genetic Relatedness of Low Solitary Nests of Apis dorsata from Marang, Terengganu, Malaysia

PubMed Central

Ali, Abdul Manaf; Tan, Soon Guan; Adam, Nur Azura; Lau, Wei Hong

2012-01-01

Knowledge on the population of genetic structure and ecological behaviour of Apis dorsata from Peninsular Malaysia is needed for effective management and conservation of this species since unsustainable whole solitary low nest cutting for product harvesting is the current common practice here. The analysis of 15 single locus DNA microsatellite markers on samples from 20 solitary nests of A. dorsata showed that while these markers were polymorphic, high intracolonial relatedness existed. Furthermore, in general, slightly negative values of intercolony relatedness (R) among the nests of A. dorsata were found. However, positive values of mean intercolony relatedness were observed between 54 pairs of nests out of 190 possible combinations. The R values among nest pairs 3–4 and 3–5 was higher than 0.50 showing that their queens were half siblings, whereas nest pair 19–20 showed relatedness of 0.95 indicating that the same queen was sampled. The results that we obtained could not conclusively support the hypothesis of this study that the honey hunters in Marang district of Malaysia repeatedly harvest the same nest located at a different site and at a different time during the same honey harvesting season. However, our finding of an appreciable level of intercolonial relatedness between several pairs of nests in this pioneer study indicated that a comprehensive study with a larger sample size of solitary nests found throughout the region would be necessary to provide concrete proof for this novel idea. PMID:22911733

Local individual preferences for nest materials in a passerine bird.

PubMed

Mennerat, Adèle; Perret, Philippe; Lambrechts, Marcel M

2009-01-01

Variation in the behavioural repertoire of animals is acquired by learning in a range of animal species. In nest-building birds, the assemblage of nest materials in an appropriate structure is often typical of a bird genus or species. Yet plasticity in the selection of nest materials may be beneficial because the nature and abundance of nest materials vary across habitats. Such plasticity can be learned, either individually or socially. In Corsican populations of blue tits Cyanistes caeruleus, females regularly add in their nests fragments of several species of aromatic plants during the whole breeding period. The selected plants represent a small fraction of the species present in the environment and have positive effects on nestlings. We investigated spatiotemporal variations of this behaviour to test whether the aromatic plant species composition in nests depends on 1) plant availability in territories, 2) female experience or 3) female identity. Our results indicate that territory plays a very marginal role in the aromatic plant species composition of nests. Female experience is not related to a change in nest plant composition. Actually, this composition clearly depends on female identity, i.e. results from individual preferences which, furthermore, are repeatable both within and across years. A puzzling fact is the strong difference in plant species composition of nests across distinct study plots. This study demonstrates that plant species composition of nests results from individual preferences that are homogeneous within study plots. We propose several hypotheses to interpret this pattern of spatial variation before discussing them in the light of preliminary results. As a conclusion, we cannot exclude the possibility of social transmission of individual preferences for aromatic plants. This is an exciting perspective for further work in birds, where nest construction behaviour has classically been considered as a stereotypic behaviour.

WRF nested large-eddy simulations of deep convection during SEAC4RS

NASA Astrophysics Data System (ADS)

Heath, Nicholas Kyle

Deep convection is an important component of atmospheric circulations that affects many aspects of weather and climate. Therefore, improved understanding and realistic simulations of deep convection are critical to both operational and climate forecasts. Large-eddy simulations (LESs) often are used with observations to enhance understanding of convective processes. This study develops and evaluates a nested-LES method using the Weather Research and Forecasting (WRF) model. Our goal is to evaluate the extent to which the WRF nested-LES approach is useful for studying deep convection during a real-world case. The method was applied on 2 September 2013, a day of continental convection having a robust set of ground and airborne data available for evaluation. A three domain mesoscale WRF simulation is run first. Then, the finest mesoscale output (1.35 km grid length) is used to separately drive nested-LES domains with grid lengths of 450 and 150 m. Results reveal that the nested-LES approach reasonably simulates a broad spectrum of observations, from reflectivity distributions to vertical velocity profiles, during the study period. However, reducing the grid spacing does not necessarily improve results for our case, with the 450 m simulation outperforming the 150 m version. We find that simulated updrafts in the 150 m simulation are too narrow to overcome the negative effects of entrainment, thereby generating convection that is weaker than observed. Increasing the sub-grid mixing length in the 150 m simulation leads to deeper, more realistic convection, but comes at the expense of delaying the onset of the convection. Overall, results show that both the 450 m and 150 m simulations are influenced considerably by the choice of sub-grid mixing length used in the LES turbulence closure. Finally, the simulations and observations are used to study the processes forcing strong midlevel cloud-edge downdrafts that were observed on 2 September. Results suggest that these downdrafts are forced by evaporative cooling due to mixing near cloud edge and by vertical perturbation pressure gradient forces acting to restore mass continuity around neighboring updrafts. We conclude that the WRF nested-LES approach provides an effective method for studying deep convection for our real-world case. The method can be used to provide insight into physical processes that are important to understanding observations. The WRF nested-LES approach could be adapted for other case studies in which high-resolution observations are available for validation.

CyNEST: a maintainable Cython-based interface for the NEST simulator

PubMed Central

Zaytsev, Yury V.; Morrison, Abigail

2014-01-01

NEST is a simulator for large-scale networks of spiking point neuron models (Gewaltig and Diesmann, 2007). Originally, simulations were controlled via the Simulation Language Interpreter (SLI), a built-in scripting facility implementing a language derived from PostScript (Adobe Systems, Inc., 1999). The introduction of PyNEST (Eppler et al., 2008), the Python interface for NEST, enabled users to control simulations using Python. As the majority of NEST users found PyNEST easier to use and to combine with other applications, it immediately displaced SLI as the default NEST interface. However, developing and maintaining PyNEST has become increasingly difficult over time. This is partly because adding new features requires writing low-level C++ code intermixed with calls to the Python/C API, which is unrewarding. Moreover, the Python/C API evolves with each new version of Python, which results in a proliferation of version-dependent code branches. In this contribution we present the re-implementation of PyNEST in the Cython language, a superset of Python that additionally supports the declaration of C/C++ types for variables and class attributes, and provides a convenient foreign function interface (FFI) for invoking C/C++ routines (Behnel et al., 2011). Code generation via Cython allows the production of smaller and more maintainable bindings, including increased compatibility with all supported Python releases without additional burden for NEST developers. Furthermore, this novel approach opens up the possibility to support alternative implementations of the Python language at no cost given a functional Cython back-end for the corresponding implementation, and also enables cross-compilation of Python bindings for embedded systems and supercomputers alike. PMID:24672470

Nest and chick survival and colony-site dynamics of least terns in the U.S. Virgin Islands

USGS Publications Warehouse

Lombard, Claudia D.; Collazo, Jaime; McNair, Douglas B.

2010-01-01

We report nest and chick survival and colony-site dynamics of the Least Tern (Sternula antillarum). These results are the first for the Caribbean and were derived with likelihood-based approaches from 4640 nests and 44 chicks fitted with transmitters monitored in 52 colonies at St. Croix, U.S. Virgin Islands, 2003–2006. Managed colonies excluded, overall daily nest survival (±SE) was 0.92 ± 0.03 (period survival = 0.18). Daily nest survival of managed colonies (fenced) was significantly higher (0.97 ± 0.02; period survival = 0.51). Variation in nest survival was best explained by a negative linear trend in daily survival, influenced by year, rain, large colony size, and nesting habitat. Daily nest-survival rates at sandy beaches (0.94 ± 0.02), offshore cays (0.93 ± 0.005), and saltflats (0.91 ± 0.02) did not differ significantly. The period survival of chicks was 0.30 ± 0.11. Estimated fledglings per nest attempt were 0.06. Demographic assessments suggested that higher reproductive rates are required for maintenance (λ ≥ 1). Managed colonies could meet nest-survival thresholds, but complementary measures are needed to increase chick survival. Our findings suggest that management should target sites harboring large colonies because they had higher nest success and higher probability of use in subsequent seasons. The colonies' site dynamics suggested that immigration from other populations is plausible. This possibility relaxes breeding-productivity thresholds and advocates for coordinated conservation among populations on neighboring islands. Estimates of age-specific survival and connectivity are needed for the status of the species to be assessed appropriately and conservation priorities set.

Spatial Ecology of Estuarine Crocodile (Crocodylus porosus) Nesting in a Fragmented Landscape.

PubMed

Evans, Luke J; Jones, T Hefin; Pang, Keeyen; Saimin, Silvester; Goossens, Benoit

2016-09-19

The role that oil palm plays in the Lower Kinabatangan region of Eastern Sabah is of considerable scientific and conservation interest, providing a model habitat for many tropical regions as they become increasingly fragmented. Crocodilians, as apex predators, widely distributed throughout the tropics, are ideal indicator species for ecosystem health. Drones (or unmanned aerial vehicles (UAVs)) were used to identify crocodile nests in a fragmented landscape. Flights were targeted through the use of fuzzy overlay models and nests located primarily in areas indicated as suitable habitat. Nests displayed a number of similarities in terms of habitat characteristics allowing for refined modelling of survey locations. As well as being more cost-effective compared to traditional methods of nesting survey, the use of drones also enabled a larger survey area to be completed albeit with a limited number of flights. The study provides a methodology for targeted nest surveying, as well as a low-cost repeatable flight methodology. This approach has potential for widespread applicability across a range of species and for a variety of study designs.

Spatial Ecology of Estuarine Crocodile (Crocodylus porosus) Nesting in a Fragmented Landscape

PubMed Central

Evans, Luke J.; Jones, T. Hefin; Pang, Keeyen; Saimin, Silvester; Goossens, Benoit

2016-01-01

The role that oil palm plays in the Lower Kinabatangan region of Eastern Sabah is of considerable scientific and conservation interest, providing a model habitat for many tropical regions as they become increasingly fragmented. Crocodilians, as apex predators, widely distributed throughout the tropics, are ideal indicator species for ecosystem health. Drones (or unmanned aerial vehicles (UAVs)) were used to identify crocodile nests in a fragmented landscape. Flights were targeted through the use of fuzzy overlay models and nests located primarily in areas indicated as suitable habitat. Nests displayed a number of similarities in terms of habitat characteristics allowing for refined modelling of survey locations. As well as being more cost-effective compared to traditional methods of nesting survey, the use of drones also enabled a larger survey area to be completed albeit with a limited number of flights. The study provides a methodology for targeted nest surveying, as well as a low-cost repeatable flight methodology. This approach has potential for widespread applicability across a range of species and for a variety of study designs. PMID:27657065

Parathion alters incubation behavior of laughing gulls

USGS Publications Warehouse

White, D.H.; Mitchell, C.A.; Hill, E.F.

1983-01-01

One member of each pair of incubating laughing gulls at 9 nests was trapped, orally dosed with either 6 mg/kg parathion in corn oil or corn oil alone, and marked about the neck with red dye. Each nest was marked with a numbered stake and the treatment was recorded. A pilot study with captive laughing gulls had determined the proper dosage of parathion that would significantly inhibit their brain AChE activity (about 50% of normal) without overt signs of poisoning. After dosing, birds were released and the nests were observed for 2 1/2 days from a blind on the nesting island. The activities of the birds at each marked nest were recorded at 10-minute intervals. Results indicated that on the day of treatment there was no difference (P greater than 0.05, Chi-square test) in the proportion of time spent on the nest between treated and control birds. However, birds dosed with 6 mg/kg parathion spent significantly less time incubating on days 2 and 3 than did birds receiving only corn oil. By noon on the third day, sharing of nest duties between pair members in the treated group had approached normal, indicating recovery from parathion intoxication. These findings suggest that sublethal exposure of nesting birds to an organophosphate (OP) insecticide, such as parathion, may result in decreased nest attentiveness, thereby making the clutch more susceptible to predation or egg failure. Behavioral changes caused by sublethal OP exposure could be especially detrimental in avian species where only one pair member incubates or where both members are exposed in species sharing nest duties.

Comparison of Two Grid Refinement Approaches for High Resolution Regional Climate Modeling: MPAS vs WRF

NASA Astrophysics Data System (ADS)

Leung, L.; Hagos, S. M.; Rauscher, S.; Ringler, T.

2012-12-01

This study compares two grid refinement approaches using global variable resolution model and nesting for high-resolution regional climate modeling. The global variable resolution model, Model for Prediction Across Scales (MPAS), and the limited area model, Weather Research and Forecasting (WRF) model, are compared in an idealized aqua-planet context with a focus on the spatial and temporal characteristics of tropical precipitation simulated by the models using the same physics package from the Community Atmosphere Model (CAM4). For MPAS, simulations have been performed with a quasi-uniform resolution global domain at coarse (1 degree) and high (0.25 degree) resolution, and a variable resolution domain with a high-resolution region at 0.25 degree configured inside a coarse resolution global domain at 1 degree resolution. Similarly, WRF has been configured to run on a coarse (1 degree) and high (0.25 degree) resolution tropical channel domain as well as a nested domain with a high-resolution region at 0.25 degree nested two-way inside the coarse resolution (1 degree) tropical channel. The variable resolution or nested simulations are compared against the high-resolution simulations that serve as virtual reality. Both MPAS and WRF simulate 20-day Kelvin waves propagating through the high-resolution domains fairly unaffected by the change in resolution. In addition, both models respond to increased resolution with enhanced precipitation. Grid refinement induces zonal asymmetry in precipitation (heating), accompanied by zonal anomalous Walker like circulations and standing Rossby wave signals. However, there are important differences between the anomalous patterns in MPAS and WRF due to differences in the grid refinement approaches and sensitivity of model physics to grid resolution. This study highlights the need for "scale aware" parameterizations in variable resolution and nested regional models.

Cost-efficient designs for three-arm trials with treatment delivered by health professionals: Sample sizes for a combination of nested and crossed designs

PubMed Central

Moerbeek, Mirjam

2018-01-01

Background This article studies the design of trials that compare three treatment conditions that are delivered by two types of health professionals. The one type of health professional delivers one treatment, and the other type delivers two treatments, hence, this design is a combination of a nested and crossed design. As each health professional treats multiple patients, the data have a nested structure. This nested structure has thus far been ignored in the design of such trials, which may result in an underestimate of the required sample size. In the design stage, the sample sizes should be determined such that a desired power is achieved for each of the three pairwise comparisons, while keeping costs or sample size at a minimum. Methods The statistical model that relates outcome to treatment condition and explicitly takes the nested data structure into account is presented. Mathematical expressions that relate sample size to power are derived for each of the three pairwise comparisons on the basis of this model. The cost-efficient design achieves sufficient power for each pairwise comparison at lowest costs. Alternatively, one may minimize the total number of patients. The sample sizes are found numerically and an Internet application is available for this purpose. The design is also compared to a nested design in which each health professional delivers just one treatment. Results Mathematical expressions show that this design is more efficient than the nested design. For each pairwise comparison, power increases with the number of health professionals and the number of patients per health professional. The methodology of finding a cost-efficient design is illustrated using a trial that compares treatments for social phobia. The optimal sample sizes reflect the costs for training and supervising psychologists and psychiatrists, and the patient-level costs in the three treatment conditions. Conclusion This article provides the methodology for designing trials that compare three treatment conditions while taking the nesting of patients within health professionals into account. As such, it helps to avoid underpowered trials. To use the methodology, a priori estimates of the total outcome variances and intraclass correlation coefficients must be obtained from experts’ opinions or findings in the literature. PMID:29316807

Landscape heterogeneity drives intra-population niche variation and reproduction in an arctic top predator

PubMed Central

L'Hérault, Vincent; Franke, Alastair; Lecomte, Nicolas; Alogut, Adam; Bêty, Joël

2013-01-01

While intra-population variability in resource use is ubiquitous, little is known of how this measure of niche diversity varies in space and its role in population dynamics. Here we examined how heterogeneous breeding environments can structure intra-population niche variation in both resource use and reproductive output. We investigated intra-population niche variation in the Arctic tundra ecosystem, studying peregrine falcon (Falco peregrinus tundrius, White) breeding within a terrestrial-marine gradient near Rankin Inlet, Nunavut, Canada. Using stable isotope analysis, we found that intra-population niches varied at the individual level; we examined within-nest and among-nest variation, though only the latter varied along the terrestrial-marine gradient (i.e., increased among-nest variability among birds nesting within the marine environment, indicating higher degree of specialization). Terrestrial prey species (small herbivores and insectivores) were consumed by virtually all falcons. Falcons nesting within the marine environment made use of marine prey (sea birds), but depended heavily on terrestrial prey (up to 90% of the diet). Using 28-years of peregrine falcon nesting data, we found a positive relationship between the proportion of terrestrial habitat surrounding nest sites and annual nestling production, but no relationship with the likelihood of successfully rearing at least one nestling reaching 25 days old. Annually, successful inland breeders raised 0.47 more young on average compared to offshore breeders, which yields potential fitness consequences for this long-living species. The analyses of niche and reproductive success suggest a potential breeding cost for accessing distant terrestrial prey, perhaps due to additional traveling costs, for those individuals with marine nest site locations. Our study indicates how landscape heterogeneity can generate proximate (niche variation) and ultimate (reproduction) consequences on a population of generalist predator. We also show that within-individual and among-individual variation are not mutually exclusive, but can simultaneously arise and structure intra-population niche variation. PMID:24101979

Resource Quantity and Quality Determine the Inter-Specific Associations between Ecosystem Engineers and Resource Users in a Cavity-Nest Web

PubMed Central

Robles, Hugo; Martin, Kathy

2013-01-01

While ecosystem engineering is a widespread structural force of ecological communities, the mechanisms underlying the inter-specific associations between ecosystem engineers and resource users are poorly understood. A proper knowledge of these mechanisms is, however, essential to understand how communities are structured. Previous studies suggest that increasing the quantity of resources provided by ecosystem engineers enhances populations of resource users. In a long-term study (1995-2011), we show that the quality of the resources (i.e. tree cavities) provided by ecosystem engineers is also a key feature that explains the inter-specific associations in a tree cavity-nest web. Red-naped sapsuckers ( Sphyrapicus nuchalis ) provided the most abundant cavities (52% of cavities, 0.49 cavities/ha). These cavities were less likely to be used than other cavity types by mountain bluebirds ( Sialia currucoides ), but provided numerous nest-sites (41% of nesting cavities) to tree swallows ( Tachycineta bicolour ). Swallows experienced low reproductive outputs in northern flicker ( Colaptes auratus ) cavities compared to those in sapsucker cavities (1.1 vs. 2.1 fledglings/nest), but the highly abundant flickers (33% of cavities, 0.25 cavities/ha) provided numerous suitable nest-sites for bluebirds (58%). The relative shortage of cavities supplied by hairy woodpeckers ( Picoides villosus ) and fungal/insect decay (<10% of cavities each, <0.09 cavities/ha) provided fewer breeding opportunities (<15% of nests), but represented high quality nest-sites for both bluebirds and swallows. Because both the quantity and quality of resources supplied by different ecosystem engineers may explain the amount of resources used by each resource user, conservation strategies may require different management actions to be implemented for the key ecosystem engineer of each resource user. We, therefore, urge the incorporation of both resource quantity and quality into models that assess community dynamics to improve conservation actions and our understanding of ecological communities based on ecosystem engineering. PMID:24040324

Resource quantity and quality determine the inter-specific associations between ecosystem engineers and resource users in a cavity-nest web.

PubMed

Robles, Hugo; Martin, Kathy

2013-01-01

While ecosystem engineering is a widespread structural force of ecological communities, the mechanisms underlying the inter-specific associations between ecosystem engineers and resource users are poorly understood. A proper knowledge of these mechanisms is, however, essential to understand how communities are structured. Previous studies suggest that increasing the quantity of resources provided by ecosystem engineers enhances populations of resource users. In a long-term study (1995-2011), we show that the quality of the resources (i.e. tree cavities) provided by ecosystem engineers is also a key feature that explains the inter-specific associations in a tree cavity-nest web. Red-naped sapsuckers (Sphyrapicusnuchalis) provided the most abundant cavities (52% of cavities, 0.49 cavities/ha). These cavities were less likely to be used than other cavity types by mountain bluebirds (Sialiacurrucoides), but provided numerous nest-sites (41% of nesting cavities) to tree swallows (Tachycinetabicolour). Swallows experienced low reproductive outputs in northern flicker (Colaptesauratus) cavities compared to those in sapsucker cavities (1.1 vs. 2.1 fledglings/nest), but the highly abundant flickers (33% of cavities, 0.25 cavities/ha) provided numerous suitable nest-sites for bluebirds (58%). The relative shortage of cavities supplied by hairy woodpeckers (Picoidesvillosus) and fungal/insect decay (<10% of cavities each, <0.09 cavities/ha) provided fewer breeding opportunities (<15% of nests), but represented high quality nest-sites for both bluebirds and swallows. Because both the quantity and quality of resources supplied by different ecosystem engineers may explain the amount of resources used by each resource user, conservation strategies may require different management actions to be implemented for the key ecosystem engineer of each resource user. We, therefore, urge the incorporation of both resource quantity and quality into models that assess community dynamics to improve conservation actions and our understanding of ecological communities based on ecosystem engineering.

Successful nesting by a Bald Eagle pair in prairie grasslands of the Texas Panhandle

USGS Publications Warehouse

Boal, G.W.; Giovanni, M.D.; Beall, B.N.

2006-01-01

We observed a breeding Bald Eagle (Haliaeetus leitcocephalus) pair nesting in a short-grass prairie and agricultural community on the southern Great Plains of the Texas Panhandle in 2004 and 2005. The nesting eagles produced 1 fledgling in 2004 and 2 fledglings in 2005. Our assessment of landcover types within a 5-km radius of the nest indicated that grasslands accounted for most of the area (90%), followed by agricultural lands (8%). Black-tailed prairie dog (Cynomys ludovicianus) colonies occupied 2.5% of the area, and single human residences with associated structures (i.e., barns) occupied 2.5 ha in surface area was 51 km from the nest. An analysis of regurgitated castings collected near the nest revealed a mammalian-dominated, breeding-season diet with black-tailed prairie dogs occurring in 80.9% of the castings. Other identified prey included cottontails (Sylvilagus spp., 15.9%), black-tailed jackrabbits (Lepus californicus, 3.2%), pronghorn (Antilocapra americana, 3.2%), and plains pocket gopher (Geomys bursarius, 1.6%). Bird remains were also present in 34.9% of the castings. This is the first reported successful nesting of Bald Eagles in the panhandle region of Texas since 1916; the nest is particularly unique because of its distance from any substantial body of water.

A meta-analysis of lesser prairie-chicken nesting and brood-rearing habitats: implications for habitat management

USGS Publications Warehouse

Hagen, Christian A.; Grisham, Blake A.; Boal, Clint W.; Haukos, David A.

2013-01-01

The distribution and range of lesser prairie-chicken (Tympanuchus pallidicinctus) has been reduced by >90% since European settlement of the Great Plains of North America. Currently, lesser prairie-chickens occupy 3 general vegetation communities: sand sagebrush (Artemisia filifolia), sand shinnery oak (Quercus havardii), and mixed-grass prairies juxtaposed with Conservation Reserve Program grasslands. As a candidate for protection under the Endangered Species Act, there is a need for a synthesis that characterizes habitat structure rangewide. Thus, we conducted a meta-analysis of vegetation characteristics at nest sites and brood habitats to determine whether there was an overall effect (Hedges' d) of habitat selection and to estimate average (95% CI) habitat characteristics at use sites. We estimated effect sizes (di) from the difference between use (nests and brood sites) and random sampling sites for each study (n = 14), and derived an overall effect size (d++). There was a general effect for habitat selection as evidenced by low levels of variation in effect sizes across studies and regions. There was a small to medium effect (d++) = 0.20-0.82) of selection for greater vertical structure (visual obstruction) by nesting females in both vegetation communities, and selection against bare ground (d++ = 0.20-0.58). Females with broods exhibited less selectivity for habitat components except for vertical structure. The variation of d++ was greater during nesting than brooding periods, signifying a seasonal shift in habitat use, and perhaps a greater range of tolerance for brood-rearing habitat. The overall estimates of vegetation cover were consistent with those provided in management guidelines for the species.

Nested Tracking Graphs

DOE PAGES

Lukasczyk, Jonas; Weber, Gunther; Maciejewski, Ross; ...

2017-06-01

Tracking graphs are a well established tool in topological analysis to visualize the evolution of components and their properties over time, i.e., when components appear, disappear, merge, and split. However, tracking graphs are limited to a single level threshold and the graphs may vary substantially even under small changes to the threshold. To examine the evolution of features for varying levels, users have to compare multiple tracking graphs without a direct visual link between them. We propose a novel, interactive, nested graph visualization based on the fact that the tracked superlevel set components for different levels are related to eachmore » other through their nesting hierarchy. This approach allows us to set multiple tracking graphs in context to each other and enables users to effectively follow the evolution of components for different levels simultaneously. We show the effectiveness of our approach on datasets from finite pointset methods, computational fluid dynamics, and cosmology simulations.« less

A Method to Represent Heterogeneous Materials for Rapid Prototyping: The Matryoshka Approach

PubMed Central

Lei, Shuangyan; Frank, Matthew C.; Anderson, Donald D.; Brown, Thomas D.

2015-01-01

Purpose The purpose of this paper is to present a new method for representing heterogeneous materials using nested STL shells, based, in particular, on the density distributions of human bones. Design/methodology/approach Nested STL shells, called Matryoshka models, are described, based on their namesake Russian nesting dolls. In this approach, polygonal models, such as STL shells, are “stacked” inside one another to represent different material regions. The Matryoshka model addresses the challenge of representing different densities and different types of bone when reverse engineering from medical images. The Matryoshka model is generated via an iterative process of thresholding the Hounsfield Unit (HU) data using computed tomography (CT), thereby delineating regions of progressively increasing bone density. These nested shells can represent regions starting with the medullary (bone marrow) canal, up through and including the outer surface of the bone. Findings The Matryoshka approach introduced can be used to generate accurate models of heterogeneous materials in an automated fashion, avoiding the challenge of hand-creating an assembly model for input to multi-material additive or subtractive manufacturing. Originality/Value This paper presents a new method for describing heterogeneous materials: in this case, the density distribution in a human bone. The authors show how the Matryoshka model can be used to plan harvesting locations for creating custom rapid allograft bone implants from donor bone. An implementation of a proposed harvesting method is demonstrated, followed by a case study using subtractive rapid prototyping to harvest a bone implant from a human tibia surrogate. PMID:26120277

Spectrum of lesions derived from branchial arches occurring in the thyroid: from solid cell nests to tumors.

PubMed

Srbecka, Kristyna; Michalova, Kvetoslava; Curcikova, Radmila; Michal, Michael; Dubova, Magdalena; Svajdler, Marian; Michal, Michal; Daum, Ondrej

2017-09-01

There is a group of lesions in the head and neck region derived from branchial arches and related structures which, when inflamed, are characterized by the formation of cysts lined by squamous or glandular epithelium and surrounded by a heavy inflammatory infiltrate rich in germinal centers. In the thyroid, the main source of various structures which may cause diagnostic dilemma is the ultimobranchial body. To investigate the spectrum of such thyroid lesions, the consultation files were reviewed for thyroid samples containing pathological structures regarded to arise from the ultimobranchial body. Positive reaction with antibodies against CK5/6, p63, galectin 3, and CEA, and negative reaction with antibodies against thyroglobulin, TTF-1, and calcitonin were used to confirm the diagnosis. The specific subtype of the ultimobranchial body-derived lesion was then determined based on histological examination of H&E-stained slides. Twenty-one cases of ultimobranchial body-derived lesions were retrieved from the consultation files, 20 of them along with clinical information (M/F = 6/14, mean age 55 years, range 36-68 years). Lesions derived from the ultimobranchial body were classified as follows: (hyperplastic) solid cell nests (nine cases), solid cell nests with focal cystic change (five cases), cystic solid cell nests (two cases), branchial cleft-like cyst (four cases), and finally a peculiar Warthin tumor-like lesion (one case). We suggest that the common denominator of these structures is that they all arise due to activation of inflammatory cells around the vestigial structures, which leads to cystic dilatation and proliferation of the epithelial component.

Population structuring of the ubiquitous stingless bee Tetragonisca angustula in southern Brazil as revealed by microsatellite and mitochondrial markers.

PubMed

Francisco, Flávio O; Santiago, Leandro R; Mizusawa, Yuri M; Oldroyd, Benjamin P; Arias, Maria C

2017-10-01

Tetragonisca angustula is one of the most widespread stingless bees in the Neotropics. This species swarms frequently and is extremely successful in urban environments. In addition, it is one of the most popular stingless bee species for beekeeping in Latin America, so nest transportation and trading is common. Nest transportation can change the genetic structure of the host population, reducing inbreeding and increasing homogenization. Here, we evaluate the genetic structure of 17 geographic populations of T. angustula in southern Brazil to quantify the level of genetic differentiation between populations. Analyses were conducted on partially sequenced mitochondrial genes and 11 microsatellite loci of 1002 workers from 457 sites distributed on the mainland and on 3 islands. Our results show that T. angustula populations are highly differentiated as demonstrated by mitochondrial DNA (mtDNA) and microsatellite markers. Of 73 haplotypes, 67 were population-specific. MtDNA diversity was low in 9 populations but microsatellite diversity was moderate to high in all populations. Microsatellite data suggest 10 genetic clusters and low level of gene flow throughout the studied area. However, physical barriers, such as rivers and mountain ranges, or the presence or absence of forest appear to be unrelated to population clusters. Factors such as low dispersal, different ecological conditions, and isolation by distance are most likely shaping the population structure of this species. Thus far, nest transportation has not influenced the general population structure in the studied area. However, due to the genetic structure we found, we recommend that nest transportation should only occur within and between populations that are genetically similar. © 2016 Institute of Zoology, Chinese Academy of Sciences.

Inflatable nested toroid structure

NASA Technical Reports Server (NTRS)

Johnson, Christopher J. (Inventor); Raboin, Jasen L. (Inventor); Spexarth, Gary R. (Inventor)

2011-01-01

An inflatable structure comprises at least two generally toroidal, inflatable modules. When in a deployed mode, the first, inner module has a major diameter less than that of a second, outer module and is positioned within the inner circumference of the outer module such that the first module is nested circumferentially alongside the second module. The inflatable structure, in a non-deployed, non-inflated mode, is of compact configuration and adapted to be transported to a site of deployment. When deployed, the inflatable structure is of substantially increased interior volume. In one embodiment, access between the interior of the first module and the second module is provided by at least one port or structural pass-through. In another embodiment, the inflatable structure includes at least one additional generally toroidal module external of and circumferentially surrounding the second module.

A new biodegradable sisal fiber-starch packing composite with nest structure.

PubMed

Xie, Qi; Li, Fangyi; Li, Jianfeng; Wang, Liming; Li, Yanle; Zhang, Chuanwei; Xu, Jie; Chen, Shuai

2018-06-01

A new completely biodegradable sisal fiber-starch packing composite was proposed. The effects of fiber content and alkaline treatment on the cushioning property of the composites were studied from energy absorption efficiency, cellular microstructure and compatibility between fiber and starch. With increasing fiber content, the nest structure of composites becomes dense first and then loosens, resulting in initial enhancement and subsequent weakening of the cushioning property of the composites. The composite with 4:13 mass ratio of fiber and thermoplastic starch (TPS) exhibit the optimal cushioning property. Alkaline treatment increases the compatibility between sisal fiber and TPS, promotes the formation of dense nest structure, thereby enhances the cushioning property of the composites. After biodegradability tests for 28 days, the weight loss of the composites was 62.36%. It's found that the composites are a promising replacement for expandable polystyrene (EPS) as packing material, especially under large compression load (0.7-6 MPa). Copyright © 2018 Elsevier Ltd. All rights reserved.

Management and protection protocols for nesting sea turtles on Cape Hatteras National Seashore, North Carolina

USGS Publications Warehouse

Cohen, J.B.

2005-01-01

Executive Summary 1. The southeast U.S. population of the loggerhead turtle (Caretta caretta) has increased since the species was listed as federally threatened in 1978. Since standardized monitoring began in North Carolina in 1995, the number of nests at Cape Hatteras National Seashore (CAHA) fluctuated from year to year, and was lowest in 1996 and 1997 (39 nests) and highest in 2003 (101 nests). Green turtles (Chelonia mydas) and leatherback turtles (Dermochelys coriacea) have nested in small numbers at CAHA, sporadically over time. 2. Hatching success of sea turtle nests typically approaches 80%. At CAHA hatching success from 1999-2003 was low when hurricanes hit during the nesting season (30%-38%), and ranged from 52%-70% otherwise. Hatching success at CAHA is usually correlated with hatching success in the surrounding subpopulation (north Florida to North Carolina). 3. Inclement weather, predation, and human recreation can negatively impact nesting rate and hatching success. 4. Currently there is little protection from recreation at CAHA for nesting females and nests that have not been found by monitors. We propose three management options to provide such protection, and to increase protection for known nests and hatchlings. We propose an adaptive management framework for assessing the effectiveness of these management options in improving sea turtle nesting rate and nest and hatchling survival. 5. We recommend continued efforts to trap and remove mammalian predators from all sea turtle habitat. We further recommend intensive monitoring and surveillance of protected areas to determine the extent and timing of threats to nests and broods, including nest overwash, predation, and disturbance or vandalism by humans. 6. Continue to relocate nests and assist stranded turtles according to North Carolina Wildlife Resources Commission guidelines. 7. Artificial light sources pose a serious threat to sea turtles in some parts of CAHA, which must be remedied immediately. We recommend that CAHA enact turtle-friendly lighting regulations and work with the communities within its borders to reduce light pollution and to eliminate artificial light sources that are directly visible from sea turtle nesting areas. 8. We recommend increased education and outreach to CAHA visitors, including requiring participation in an educational program before being granted nighttime beach access. The long-term success of sea turtle recovery will depend on public cooperation and positive public attitudes toward sea turtles and turtle management actions.

Field guide to red tree vole nests

Treesearch

Damon B. Lesmeister; James K. Swingle

2017-01-01

Surveys for red tree vole (Arborimus longicaudus) nests require tree climbing because the species is a highly specialized arboreal rodent that live in the tree canopy of coniferous forests in western Oregon and northwestern California. Tree voles are associated with old coniferous forest (≥80 years old) that are structurally complex, but are often...

Application of a Multidimensional Nested Logit Model to Multiple-Choice Test Items

ERIC Educational Resources Information Center

Bolt, Daniel M.; Wollack, James A.; Suh, Youngsuk

2012-01-01

Nested logit models have been presented as an alternative to multinomial logistic models for multiple-choice test items (Suh and Bolt in "Psychometrika" 75:454-473, 2010) and possess a mathematical structure that naturally lends itself to evaluating the incremental information provided by attending to distractor selection in scoring. One potential…

Epipona media cooper (Hymenoptera: Vespidae), a social wasp new to the Brazilian Atlantic Forest.

PubMed

Menezes, Rodolpho S T; Carvalho Filho, Antonio F; Raw, Anthony; Costa, Marco A

2010-01-01

An occupied nest of Epipona media Cooper was discovered and collected in a cabruca (cocoa plantation with native tree cover). This is the first record of E. media from Bahia State. We described the nest structure and compared the adults with the closely related species Epipona tatua Cuvier.

Contents and Structure Atta texana Nest in Summer

Treesearch

John C. Moser

1963-01-01

A large nest of Atta texana (Buckley) in central Louisiana was partially excavated in August 1960. Twelve dormancy, 5 detritus, and 93 fungus-garden cavities were found. Fungus-garden cavities near the surface outnumbered those at lower depths and contained most of the fungus material and brood. Inquilines were most numerous in detritus cavities....

Phylogeography of colonially nesting seabirds, with special reference to global matrilineal patterns in the sooty tern (Sterna fuscata).

PubMed

Avise, J C; Nelson, W S; Bowen, B W; Walker, D

2000-11-01

Sooty tern (Sterna fuscata) rookeries are scattered throughout the tropical oceans. When not nesting, individuals wander great distances across open seas, but, like many other seabirds, they tend to be site-faithful to nesting locales in successive years. Here we examine the matrilineal history of sooty terns on a global scale. Assayed colonies within an ocean are poorly differentiated in mitochondrial DNA sequence, a result indicating tight historical ties. However, a shallow genealogical partition distinguishes Atlantic from Indo-Pacific rookeries. Phylogeographic patterns in the sooty tern are compared to those in other colonially nesting seabirds, as well as in the green turtle (Chelonia mydas), an analogue of tropical seabirds in some salient aspects of natural history. Phylogeographic structure within an ocean is normally weak in seabirds, unlike the pronounced matrilineal structure in green turtles. However, the phylogeographic partition between Atlantic and Indo-Pacific rookeries in sooty terns mirrors, albeit in shallower evolutionary time, the major matrilineal subdivision in green turtles. Thus, global geology has apparently influenced historical gene movements in these two circumtropical species.

Facile synthesis of bird's nest-like TiO2 microstructure with exposed (001) facets for photocatalytic degradation of methylene blue

NASA Astrophysics Data System (ADS)

Zhang, Guozhong; Zhang, Shuqu; Wang, Longlu; Liu, Ran; Zeng, Yunxiong; Xia, Xinnian; Liu, Yutang; Luo, Shenglian

2017-01-01

The scrupulous design of hierarchical structure and highly active crystal facets exposure is essential for the creation of photocatalytic system. However, it is still a big challenge for scrupulous design of TiO2 architectures. In this paper, bird's nest-like anatase TiO2 microstructure with exposed highly active (001) surface has been successfully synthesized by a facile one-step solvothermal method. Methylene blue (MB) is chosen as a model pollutant to evaluate photocatalytic activity of as-obtained TiO2 samples. The results show that the photocatalytic activity of the bird's nest-like sample is more excellent than P25 in the degradation of MB due to high specific surface area and highly active (001) crystal facets exposure when tested under simulated solar light. Besides, it can be readily separated from the photocatalytic system by sedimentation after photocatalytic reaction, which is a significant advantage against conventional powder photocatalyst. The bird's nest-like microspheres with novel structure may have potential application in photocatalysis and other fields.

Genetic variability in captive populations of the stingless bee Tetragonisca angustula.

PubMed

Santiago, Leandro R; Francisco, Flávio O; Jaffé, Rodolfo; Arias, Maria C

2016-08-01

Low genetic variability has normally been considered a consequence of animal husbandry and a major contributing factor to declining bee populations. Here, we performed a molecular analysis of captive and wild populations of the stingless bee Tetragonisca angustula, one of the most commonly kept species across South America. Microsatellite analyses showed similar genetic variability between wild and captive populations However, captive populations showed lower mitochondrial genetic variability. Male-mediated gene flow, transport and division of nests are suggested as the most probable explanations for the observed patterns of genetic structure. We conclude that increasing the number of colonies kept through nest divisions does not negatively affect nuclear genetic variability, which seems to be maintained by small-scale male dispersal and human-mediated nest transport. However, the transport of nests from distant localities should be practiced with caution given the high genetic differentiation observed between samples from western and eastern areas. The high genetic structure verified is the result of a long-term evolutionary process, and bees from distant localities may represent unique evolutionary lineages.

Self-consistent Green's function embedding for advanced electronic structure methods based on a dynamical mean-field concept

NASA Astrophysics Data System (ADS)

Chibani, Wael; Ren, Xinguo; Scheffler, Matthias; Rinke, Patrick

2016-04-01

We present an embedding scheme for periodic systems that facilitates the treatment of the physically important part (here a unit cell or a supercell) with advanced electronic structure methods, that are computationally too expensive for periodic systems. The rest of the periodic system is treated with computationally less demanding approaches, e.g., Kohn-Sham density-functional theory, in a self-consistent manner. Our scheme is based on the concept of dynamical mean-field theory formulated in terms of Green's functions. Our real-space dynamical mean-field embedding scheme features two nested Dyson equations, one for the embedded cluster and another for the periodic surrounding. The total energy is computed from the resulting Green's functions. The performance of our scheme is demonstrated by treating the embedded region with hybrid functionals and many-body perturbation theory in the GW approach for simple bulk systems. The total energy and the density of states converge rapidly with respect to the computational parameters and approach their bulk limit with increasing cluster (i.e., computational supercell) size.

Hybrid Nested Partitions and Math Programming Framework for Large-scale Combinatorial Optimization

DTIC Science & Technology

2010-03-31

optimization problems: 1) exact algorithms and 2) metaheuristic algorithms . This project will integrate concepts from these two technologies to develop...optimal solutions within an acceptable amount of computation time, and 2) metaheuristic algorithms such as genetic algorithms , tabu search, and the...integer programming decomposition approaches, such as Dantzig Wolfe decomposition and Lagrangian relaxation, and metaheuristics such as the Nested

Relationship of songbird nest concealment to nest fate and flushing behavior of adults

Treesearch

Dirk E. Burhans; Frank R. III Thompson

2001-01-01

Advoiding predation is an important consideration for any potential prey animal. Failure to escape from a predator results in loss of fitness, so there is strong selection for choices and behaviors that result in successful escape (Lima and Dill 1990). In their cost-benefit approach to flight from predators, Ydenberg and Dill (1986) stressed that flight should be...

Convergent evolution: floral guides, stingless bee nest entrances, and insectivorous pitchers

NASA Astrophysics Data System (ADS)

Biesmeijer, Jacobus C.; Giurfa, Martin; Koedam, Dirk; Potts, Simon G.; Joel, Daniel M.; Dafni, Amots

2005-09-01

Several recent hypotheses, including sensory drive and sensory exploitation, suggest that receiver biases may drive selection of biological signals in the context of sexual selection. Here we suggest that a similar mechanism may have led to convergence of patterns in flowers, stingless bee nest entrances, and pitchers of insectivorous plants. A survey of these non-related visual stimuli shows that they share features such as stripes, dark centre, and peripheral dots. Next, we experimentally show that in stingless bees the close-up approach to a flower is guided by dark centre preference. Moreover, in the approach towards their nest entrance, they have a spontaneous preference for entrance patterns containing a dark centre and disrupted ornamentation. Together with existing empirical evidence on the honeybee's and other insects’ orientation to flowers, this suggests that the signal receivers of the natural patterns we examined, mainly Hymenoptera, have spontaneous preferences for radiating stripes, dark centres, and peripheral dots. These receiver biases may have evolved in other behavioural contexts in the ancestors of Hymenoptera, but our findings suggest that they have triggered the convergent evolution of visual stimuli in floral guides, stingless bee nest entrances, and insectivorous pitchers.

Visual navigation in desert ants Cataglyphis fortis: are snapshots coupled to a celestial system of reference?

PubMed

Akesson, Susanne; Wehner, Rüdiger

2002-07-01

Central-place foraging insects such as desert ants of the genus Cataglyphis use both path integration and landmarks to navigate during foraging excursions. The use of landmark information and a celestial system of reference for nest location was investigated by training desert ants returning from an artificial feeder to find the nest at one of four alternative positions located asymmetrically inside a four-cylinder landmark array. The cylindrical landmarks were all of the same size and arranged in a square, with the nest located in the southeast corner. When released from the compass direction experienced during training (southeast), the ants searched most intensely at the fictive nest position. When instead released from any of the three alternative directions of approach (southwest, northwest or northeast), the same individuals instead searched at two of the four alternative positions by initiating their search at the position closest to the direction of approach when entering the landmark square and then returning to the position at which snapshot, current landmark image and celestial reference information were in register. The results show that, in the ants' visual snapshot memory, a memorized landmark scene can temporarily be decoupled from a memorized celestial system of reference.

Convergent evolution: floral guides, stingless bee nest entrances, and insectivorous pitchers.

PubMed

Biesmeijer, Jacobus C; Giurfa, Martin; Koedam, Dirk; Potts, Simon G; Joel, Daniel M; Dafni, Amots

2005-09-01

Several recent hypotheses, including sensory drive and sensory exploitation, suggest that receiver biases may drive selection of biological signals in the context of sexual selection. Here we suggest that a similar mechanism may have led to convergence of patterns in flowers, stingless bee nest entrances, and pitchers of insectivorous plants. A survey of these non-related visual stimuli shows that they share features such as stripes, dark centre, and peripheral dots. Next, we experimentally show that in stingless bees the close-up approach to a flower is guided by dark centre preference. Moreover, in the approach towards their nest entrance, they have a spontaneous preference for entrance patterns containing a dark centre and disrupted ornamentation. Together with existing empirical evidence on the honeybee's and other insects' orientation to flowers, this suggests that the signal receivers of the natural patterns we examined, mainly Hymenoptera, have spontaneous preferences for radiating stripes, dark centres, and peripheral dots. These receiver biases may have evolved in other behavioural contexts in the ancestors of Hymenoptera, but our findings suggest that they have triggered the convergent evolution of visual stimuli in floral guides, stingless bee nest entrances, and insectivorous pitchers.

Smothering in UK free-range flocks. Part 2: investigating correlations between disease, housing and management practices.

PubMed

Rayner, A C; Gill, R; Brass, D; Willings, T H; Bright, A

2016-09-10

Smothering, when birds group together in a way that results in death from suffocation, is a welfare and economic concern for the egg industry. This questionnaire-based study explored correlations between disease, housing, management practices and smothering on free-range farms. A binomial logistic regression approach was used to test whether question responses predicted occurrence of nest box smothers (NBS) and panic and recurring smothers (PSRS) on farms. Breed (P=0.008) and nest box manufacturer (P=0.014) predicted NBS. Breed and nest box design have been previously reported to affect nesting behaviour. The affect of nest box manufacturer found in this study may illustrate the effect of nest box design features or house layouts. Nest box manufacturer (P=0.009), feeding oyster grit or grain on the litter (P<0.001) and range use on a sunny day (P<0.001) also predicted PSRS. Implementing some management practices to encourage desirable behaviours (eg ranging) may contribute to smothering, whereas some management practices such as those aimed at occupying birds may be beneficial, illustrating the delicate balance of factors involved in free-range egg production. It is hoped that these results will stimulate further work exploring the suitability of housing design and management of laying hens in light of smothering. British Veterinary Association.

How numbers of nesting sea turtles can be overestimated by nearly a factor of two

PubMed Central

Esteban, Nicole; Mortimer, Jeanne A.

2017-01-01

Estimating the absolute number of individuals in populations and their fecundity is central to understanding the ecosystem role of species and their population dynamics as well as allowing informed conservation management for endangered species. Estimates of abundance and fecundity are often difficult to obtain for rare or cryptic species. Yet, in addition, here we show for a charismatic group, sea turtles, that are neither cryptic nor rare and whose nesting is easy to observe, that the traditional approach of direct observations of nesting has likely led to a gross overestimation of the number of individuals in populations and underestimation of their fecundity. We use high-resolution GPS satellite tags to track female green turtles throughout their nesting season in the Chagos Archipelago (Indian Ocean) and assess when and where they nested. For individual turtles, nest locations were often spread over several tens of kilometres of coastline. Assessed by satellite observations, a mean of 6.0 clutches (range 2–9, s.d. = 2.2) was laid by individuals, about twice as many as previously assumed, a finding also reported in other species and ocean basins. Taken together, these findings suggest that the actual number of nesting turtles may be almost 50% less than previously assumed. PMID:28202810

How numbers of nesting sea turtles can be overestimated by nearly a factor of two.

PubMed

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

2017-02-22

Estimating the absolute number of individuals in populations and their fecundity is central to understanding the ecosystem role of species and their population dynamics as well as allowing informed conservation management for endangered species. Estimates of abundance and fecundity are often difficult to obtain for rare or cryptic species. Yet, in addition, here we show for a charismatic group, sea turtles, that are neither cryptic nor rare and whose nesting is easy to observe, that the traditional approach of direct observations of nesting has likely led to a gross overestimation of the number of individuals in populations and underestimation of their fecundity. We use high-resolution GPS satellite tags to track female green turtles throughout their nesting season in the Chagos Archipelago (Indian Ocean) and assess when and where they nested. For individual turtles, nest locations were often spread over several tens of kilometres of coastline. Assessed by satellite observations, a mean of 6.0 clutches (range 2-9, s.d. = 2.2) was laid by individuals, about twice as many as previously assumed, a finding also reported in other species and ocean basins. Taken together, these findings suggest that the actual number of nesting turtles may be almost 50% less than previously assumed. © 2017 The Author(s).

Nest site selection by Kentish plover suggests a trade-off between nest-crypsis and predator detection strategies.

PubMed

Gómez-Serrano, Miguel Ángel; López-López, Pascual

2014-01-01

Predation is one of the main causes of adult mortality and breeding failure for ground-nesting birds. Micro-habitat structure around nests plays a critical role in minimizing predation risk. Plovers nest in sites with little vegetation cover to maximize the incubating adult visibility, but many studies suggest a trade-off between nest-crypsis and predator detection strategies. However, this trade-off has not been explored in detail because methods used so far do not allow estimating the visibility with regards to critical factors such as slope or plant permeability to vision. Here, we tested the hypothesis that Kentish plovers select exposed sites according to a predator detection strategy, and the hypothesis that more concealed nests survive longer according to a crypsis strategy. To this end, we obtained an accurate estimation of the incubating adult's field of vision through a custom built inverted periscope. Our results showed that plovers selected nest sites with higher visibility than control points randomly selected with regards to humans and dogs, although nests located in sites with higher vegetation cover survived longer. In addition, the flushing distance (i.e., the distance at which incubating adults leave the nest when they detect a potential predator) decreased with vegetation cover. Consequently, the advantages of concealing the nest were limited by the ability to detect predators, thus indirectly supporting the existence of the trade-off between crypsis and predator detection. Finally, human disturbance also constrained nest choice, forcing plovers to move to inland sites that were less suitable because of higher vegetation cover, and modulated flushing behavior, since plovers that were habituated to humans left their nests closer to potential predators. This constraint on the width of suitable breeding habitat is particularly relevant for the conservation of Kentish Plover in sand beaches, especially under the current context of coastal regression and increase of recreational activities.

Nest Site Selection by Kentish Plover Suggests a Trade-Off between Nest-Crypsis and Predator Detection Strategies

PubMed Central

Gómez-Serrano, Miguel Ángel; López-López, Pascual

2014-01-01

Predation is one of the main causes of adult mortality and breeding failure for ground-nesting birds. Micro-habitat structure around nests plays a critical role in minimizing predation risk. Plovers nest in sites with little vegetation cover to maximize the incubating adult visibility, but many studies suggest a trade-off between nest-crypsis and predator detection strategies. However, this trade-off has not been explored in detail because methods used so far do not allow estimating the visibility with regards to critical factors such as slope or plant permeability to vision. Here, we tested the hypothesis that Kentish plovers select exposed sites according to a predator detection strategy, and the hypothesis that more concealed nests survive longer according to a crypsis strategy. To this end, we obtained an accurate estimation of the incubating adult's field of vision through a custom built inverted periscope. Our results showed that plovers selected nest sites with higher visibility than control points randomly selected with regards to humans and dogs, although nests located in sites with higher vegetation cover survived longer. In addition, the flushing distance (i.e., the distance at which incubating adults leave the nest when they detect a potential predator) decreased with vegetation cover. Consequently, the advantages of concealing the nest were limited by the ability to detect predators, thus indirectly supporting the existence of the trade-off between crypsis and predator detection. Finally, human disturbance also constrained nest choice, forcing plovers to move to inland sites that were less suitable because of higher vegetation cover, and modulated flushing behavior, since plovers that were habituated to humans left their nests closer to potential predators. This constraint on the width of suitable breeding habitat is particularly relevant for the conservation of Kentish Plover in sand beaches, especially under the current context of coastal regression and increase of recreational activities. PMID:25208045

Allometric Scaling of Patrolling Rate and Nest Volume in Constrictotermes cyphergaster Termites: Hints on the Settlement of Inquilines

PubMed Central

DeSouza, Og; Araújo, Ana Paula Albano; Florencio, Daniela Faria; Rosa, Cassiano Sousa; Marins, Alessandra; Costa, Diogo Andrade; Rodrigues, Vinicius Barros; Cristaldo, Paulo Fellipe

2016-01-01

Structural and functional traits of organisms are known to be related to the size of individuals and to the size of their colonies when they belong to one. Among such traits, propensity to inquilinism in termites is known to relate positively to colony size. Larger termitaria hold larger diversity of facultative inquilines than smaller nests, whereas obligate inquilines seem unable to settle in nests smaller than a threshold volume. Respective underlying mechanisms, however, remain hypothetical. Here we test one of such hypotheses, namely, that nest defence correlates negatively to nest volume in Constrictotermes cyphergaster termites (Termitidae: Nasutitermitinae). As a surrogate to defence, we used ‘patrolling rate’, i.e., the number of termite individuals attending per unit time an experimentally damaged spot on the outer wall of their termitaria. We found that patrolling rate decayed allometrically with increasing nest size. Conspicuously higher patrolling rates occurred in smaller nests, while conspicuously lower rates occurred in larger nests presenting volumes in the vicinity of the threshold value for the establishment of inquilinism. This could be proven adaptive for the host and guest. At younger nest age, host colonies are smaller and presumably more vulnerable and unstable. Enhanced defence rates may, hence, prevent eventual risks to hosts from inquilinism at the same time that it prevents inquilines to settle in a still unstable nest. Conversely, when colonies grow and maturate enough to stand threats, they would invest in priorities other than active defence, opening an opportunity for inquilines to settle in nests which are more suitable or less risky. Under this two-fold process, cohabitation between host and inquiline could readily stabilize. PMID:26808197

PCP-induced deficits in murine nest building activity: employment of an ethological rodent behavior to mimic negative-like symptoms of schizophrenia.

PubMed

Pedersen, Christian Spang; Sørensen, Dorte Bratbo; Parachikova, Anna I; Plath, Niels

2014-10-15

Schizophrenia is a severe psychiatric disorder characterized by three symptom domains, positive (hallucinations, obsession), negative (social withdrawal, apathy, self-neglect) and cognitive (impairment in attention, memory and executive function). Whereas current medication ameliorates positive symptomatology, negative symptoms as well as cognitive dysfunctions remain untreated. The development of improved therapies for negative symptoms has proven particularly difficult, in part due to the inability of mimicking these in rodents. Here, we address the predictive validity of combining an ethologically well preserved behavior in rodents, namely nest building activity, with an established animal model of schizophrenia, the sub-chronic PCP model, for negative symptoms. Decline in rodent nesting activity has been suggested to mirror domains of negative symptoms of schizophrenia, including social withdrawal, anhedonia and self-neglect, whereas repeated treatment with the NMDAR antagonist PCP induces and exacerbates schizophrenia-like symptoms in rodents and human subjects. Using a back-translational approach of pharmacological validation, we tested the effects of two agents targeting the nicotinic α7 receptor (EVP-6124 and TC-5619) that were reported to exert some beneficial effect on negative symptoms in schizophrenic patients. Sub-chronic PCP treatment resulted in a significant nest building deficit in mice and treatment with EVP-6124 and TC-5619 reversed this PCP-induced deficit. In contrast, the atypical antipsychotic drug risperidone remained ineffective in this assay. In addition, EVP-6124, TC-5619 and risperidone were tested in the Social Interaction Test (SIT), an assay suggested to address negative-like symptoms. Results obtained in SIT were comparable to results in the nest building test (NEST). Based on these findings, we propose nest building in combination with the sub-chronic PCP model as a novel approach to assess negative-like symptoms of schizophrenia in rodents. Copyright © 2014 Elsevier B.V. All rights reserved.

Effect of Methodological and Ecological Approaches on Heterogeneity of Nest-Site Selection of a Long-Lived Vulture

PubMed Central

Moreno-Opo, Rubén; Fernández-Olalla, Mariana; Margalida, Antoni; Arredondo, Ángel; Guil, Francisco

2012-01-01

The application of scientific-based conservation measures requires that sampling methodologies in studies modelling similar ecological aspects produce comparable results making easier their interpretation. We aimed to show how the choice of different methodological and ecological approaches can affect conclusions in nest-site selection studies along different Palearctic meta-populations of an indicator species. First, a multivariate analysis of the variables affecting nest-site selection in a breeding colony of cinereous vulture (Aegypius monachus) in central Spain was performed. Then, a meta-analysis was applied to establish how methodological and habitat-type factors determine differences and similarities in the results obtained by previous studies that have modelled the forest breeding habitat of the species. Our results revealed patterns in nesting-habitat modelling by the cinereous vulture throughout its whole range: steep and south-facing slopes, great cover of large trees and distance to human activities were generally selected. The ratio and situation of the studied plots (nests/random), the use of plots vs. polygons as sampling units and the number of years of data set determined the variability explained by the model. Moreover, a greater size of the breeding colony implied that ecological and geomorphological variables at landscape level were more influential. Additionally, human activities affected in greater proportion to colonies situated in Mediterranean forests. For the first time, a meta-analysis regarding the factors determining nest-site selection heterogeneity for a single species at broad scale was achieved. It is essential to homogenize and coordinate experimental design in modelling the selection of species' ecological requirements in order to avoid that differences in results among studies would be due to methodological heterogeneity. This would optimize best conservation and management practices for habitats and species in a global context. PMID:22413023

Nest-site selection and reproductive success of greater sage-grouse in a fire-affected habitat of northwestern Nevada

USGS Publications Warehouse

Lockyer, Zachary B.; Coates, Peter S.; Casazza, Michael L.; Espinosa, Shawn; Delehanty, David J.

2015-01-01

Identifying links between micro-habitat selection and wildlife reproduction is imperative to population persistence and recovery. This information is particularly important for landscape species such as greater sage-grouse (Centrocercus urophasianus; sage-grouse). Although this species has been widely studied, because environmental factors can affect sage-grouse populations, local and regional studies are crucial for developing viable conservation strategies. We studied the habitat-use patterns of 71 radio-marked sage-grouse inhabiting an area affected by wildfire in the Virginia Mountains of northwestern Nevada during 2009–2011 to determine the effect of micro-habitat attributes on reproductive success. We measured standard vegetation parameters at nest and random sites using a multi-scale approach (range = 0.01–15,527 ha). We used an information-theoretic modeling approach to identify environmental factors influencing nest-site selection and survival, and determine whether nest survival was a function of resource selection. Sage-grouse selected micro-sites with greater shrub canopy cover and less cheatgrass (Bromus tectorum) cover than random sites. Total shrub canopy, including sagebrush (Artemisia spp.) and other shrub species, at small spatial scales (0.8 ha and 3.1 ha) was the single contributing selection factor to higher nest survival. These results indicate that reducing the risk of wildfire to maintain important sagebrush habitats could be emphasized in sage-grouse conservation strategies in Nevada. Managers may seek to mitigate the influx of annual grass invasion by preserving large intact sagebrush-dominated stands with a mixture of other shrub species. For this area of Nevada, the results suggest that ≥40% total shrub canopy cover in sage-grouse nesting areas could yield improved reproductive success. 

Nest-niche differentiation in two sympatric columbid species from a Mediterranean Tetraclinis woodland: Considerations for forest management

NASA Astrophysics Data System (ADS)

Hanane, Saâd; Yassin, Mohamed

2017-01-01

Studies of niche partitioning among Columbid species have mainly addressed food habits and foraging activities, while partitioning in relation to nest-niche differentiation has been little studied. Here we investigate whether two sympatric columbid species-Woodpigeon (Columba palumbus) and Turtle dove (Streptopelia turtur)-occupy similar niches. A total of 74 nests were monitored: 37 nests for each species. The study, conducted in June 2016, attempted to determine the factors that may play a role in nest-niche differentiation among the two sympatric columbid species in a Moroccan Thuya (Tetraclinis articulata) forest. We used Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA) to test the relevance of nest placement, proximity of food resources, forest edge and human presence variables in the nest distribution of the two species. The results show substantial niche segregation in the T. articulata nest-trees selected by Woodpigeons and Turtle doves, with selection depending primarily on the tree size and nest height. Observed nest-niche partitioning may diminish the potential for competition between these species and enhance opportunities for their coexistence. Management policies and practices aimed at ensuring the presence of mixed-sized class of Thuya trees must be prioritized. We recommend additional studies designed to: (1) reproduce the same experimental approach on other Mediterranean Thuya forests to improve our understanding of the effects of different levels of anthropogenic disturbance on the breeding behaviour of these two game species; (2) better understand the spatio-temporal dynamics of Woodpigeon and Turtle dove coexistence in the region; and (3) better identify the spatio-temporal extent of the effect of forest management on Woodpigeon and Turtle dove site occupancy.

Possibility-based robust design optimization for the structural-acoustic system with fuzzy parameters

NASA Astrophysics Data System (ADS)

Yin, Hui; Yu, Dejie; Yin, Shengwen; Xia, Baizhan

2018-03-01

The conventional engineering optimization problems considering uncertainties are based on the probabilistic model. However, the probabilistic model may be unavailable because of the lack of sufficient objective information to construct the precise probability distribution of uncertainties. This paper proposes a possibility-based robust design optimization (PBRDO) framework for the uncertain structural-acoustic system based on the fuzzy set model, which can be constructed by expert opinions. The objective of robust design is to optimize the expectation and variability of system performance with respect to uncertainties simultaneously. In the proposed PBRDO, the entropy of the fuzzy system response is used as the variability index; the weighted sum of the entropy and expectation of the fuzzy response is used as the objective function, and the constraints are established in the possibility context. The computations for the constraints and objective function of PBRDO are a triple-loop and a double-loop nested problem, respectively, whose computational costs are considerable. To improve the computational efficiency, the target performance approach is introduced to transform the calculation of the constraints into a double-loop nested problem. To further improve the computational efficiency, a Chebyshev fuzzy method (CFM) based on the Chebyshev polynomials is proposed to estimate the objective function, and the Chebyshev interval method (CIM) is introduced to estimate the constraints, thereby the optimization problem is transformed into a single-loop one. Numerical results on a shell structural-acoustic system verify the effectiveness and feasibility of the proposed methods.

Discovering the Giant Nest Architecture of Grass-Cutting Ants, Atta capiguara (Hymenoptera, Formicidae)

PubMed Central

Forti, Luiz Carlos; Protti de Andrade, Ana Paula; Camargo, Roberto da Silva; Caldato, Nadia; Moreira, Aldenise Alves

2017-01-01

Atta capiguara is a grass-cutting ant species frequently found in Cerrado biome. However, little is known about the giant nest architecture of this ant. In this study, we investigated the architecture of three A. capiguara nests from a fragment of Cerrado in Botucatu, São Paulo, Brazil. Casts were made of the nests by filling them with cement to permit better visualization of internal structures such as chambers and tunnels. After excavation, the depth and dimensions (length, width, and height) of the chambers were measured. The results showed the shape of Atta capiguara nests consisting of mounds of loose soil with unique features resembling a conic section. The fungus chambers were found distant from the mound of loose soil and were spaced apart and distributed laterally at the soil profile. The waste chambers were located beneath the largest mound of loose soil. Both the fungus and waste chambers were separated and distant. Our study contributes to a better understanding of the so far unknown nest architecture of the grass-cutting ant A. capiguara. PMID:28350352

Processing of hierarchical syntactic structure in music.

PubMed

Koelsch, Stefan; Rohrmeier, Martin; Torrecuso, Renzo; Jentschke, Sebastian

2013-09-17

Hierarchical structure with nested nonlocal dependencies is a key feature of human language and can be identified theoretically in most pieces of tonal music. However, previous studies have argued against the perception of such structures in music. Here, we show processing of nonlocal dependencies in music. We presented chorales by J. S. Bach and modified versions in which the hierarchical structure was rendered irregular whereas the local structure was kept intact. Brain electric responses differed between regular and irregular hierarchical structures, in both musicians and nonmusicians. This finding indicates that, when listening to music, humans apply cognitive processes that are capable of dealing with long-distance dependencies resulting from hierarchically organized syntactic structures. Our results reveal that a brain mechanism fundamental for syntactic processing is engaged during the perception of music, indicating that processing of hierarchical structure with nested nonlocal dependencies is not just a key component of human language, but a multidomain capacity of human cognition.

The importance of microclimate variation in determining size, growth and survival of avian offspring: experimental evidence from a cavity nesting passerine.

PubMed

Dawson, Russell D; Lawrie, Cheyenne C; O'Brien, Erin L

2005-07-01

Organisms are expected to balance energy allocation in such a way that fitness is maximized. While much research has focussed on allocation strategies of reproducing parents, in particular birds, relatively little attention has been paid to how nestlings allocate energy while in the nest. Nestling birds are faced with a trade-off between devoting energy to growth or to thermoregulation, and in altricial species it is likely that the thermal environment of the nest site influences the nature of this trade-off. Here, we experimentally investigate how altering the microclimate of nests affects the growth, size and survival, as well as cell-mediated immune (CMI) response, of nestling tree swallows (Tachycineta bicolor) in a temperate environment. We place air-activated heating pads in nests of swallows when young were between 4 days and 16 days of age, and compared performance of offspring to control nests. Our manipulation raised temperatures of heated nests by approximately 5 degrees C compared to control nests. Offspring in heated nests had enhanced survival while in the nest, and we also found that they were heavier and had longer ninth primary feathers at 16 days of age. In addition, heating nest boxes resulted in significantly faster growth of primaries, and there was a trend for growth rates of mass to also be higher in heated nests. There were no significant differences between heated and control nests in growth rate or size of tarsus at age 16 days, and we speculate that this lack of response to elevated nest temperatures may be due to growth of skeletal structures being limited by other factors such as calcium availability. We also found no difference between heated and control nests in CMI response. Nonetheless, our results show overall that increasing temperatures of nests has significant benefits that enhance the fitness of offspring. As provisioning rates to offspring did not differ between heated and control nests, we suspect that the beneficial effects of heating were not the consequence of changes in parental behaviour. Our results provide insight into factors, other than food supply, that have important consequences in determining reproductive success of birds breeding in temperate environments.

Factors affecting nest survival of Henslow's Sparrows (Ammodramus henslowii) in southern Indiana

USGS Publications Warehouse

Crimmins, Shawn M.; McKann, Patrick C.; Robb, Joseph R.; Lewis, Jason P.; Vanosdol, Teresa; Walker, Benjamin A.; Williams, Perry J.; Thogmartin, Wayne E.

2016-01-01

Populations of Henslow’s Sparrows have declined dramatically in recent decades, coinciding with widespread loss of native grassland habitat. Prescribed burning is a primary tool for maintaining grassland patches, but its effects on nest survival of Henslow’s Sparrows remains largely unknown, especially in conjunction with other factors. We monitored 135 nests of Henslow’s Sparrows at Big Oaks National Wildlife Refuge in southern Indiana from 1998–2001 in an effort to understand factors influencing nest survival, including prescribed burning of habitat. We used a mixed-effects implementation of the logistic exposure model to predict daily nest survival in an information theoretic framework. We found that daily survival declined near the onset of hatching and increased with the height of standing dead vegetation, although this relationship was weak. We found only nominal support to suggest that time since burn influenced nest survival. Overall, nest age was the most important factor in estimating daily nest survival rates. Our daily survival estimate from our marginal model (0.937) was similar to that derived from the Mayfield method (0.944) suggesting that our results are comparable to previous studies using the Mayfield approach. Our results indicate that frequent burning to limit woody encroachment into grassland habitats might benefit Henslow’s Sparrow, but that a variety of factors ultimately influence daily nest survival. However, we note that burning too frequently can also limit occupancy by Henslow’s Sparrows. We suggest that additional research is needed to determine the population-level consequences of habitat alteration and if other extrinsic factors influence demographics of Henslow’s Sparrows.

The Design of Cluster Randomized Trials with Random Cross-Classifications

ERIC Educational Resources Information Center

Moerbeek, Mirjam; Safarkhani, Maryam

2018-01-01

Data from cluster randomized trials do not always have a pure hierarchical structure. For instance, students are nested within schools that may be crossed by neighborhoods, and soldiers are nested within army units that may be crossed by mental health-care professionals. It is important that the random cross-classification is taken into account…

Computing Power of Tests of the Variance of Treatment Effects in Designs with Two Levels of Nesting

ERIC Educational Resources Information Center

Konstantopoulos, Spyros

2008-01-01

Experiments that involve nested structures may assign treatment conditions either to entire groups (such as classrooms or schools) or individuals within groups (such as students). Although typically the interest in field experiments is in determining the significance of the overall treatment effect, it is equally important to examine the…

Latent Variable Regression 4-Level Hierarchical Model Using Multisite Multiple-Cohorts Longitudinal Data. CRESST Report 801

ERIC Educational Resources Information Center

Choi, Kilchan

2011-01-01

This report explores a new latent variable regression 4-level hierarchical model for monitoring school performance over time using multisite multiple-cohorts longitudinal data. This kind of data set has a 4-level hierarchical structure: time-series observation nested within students who are nested within different cohorts of students. These…

Avian nest box selection and nest success in burned and unburned southwestern riparian forests

Treesearch

D. Max Smith; Jeffrey F. Kelly; Deborah M. Finch

2007-01-01

Riparian forest communities in the southwestern United States were historically structured by a disturbance regime of annual flooding. In recent decades, however, frequency of flooding has decreased and frequency of wildfires has increased. Riparian forests provide important breeding habitat for a large variety of bird species, and the effects of this altered...

Changes in respiratory structure and function during post-diapause development in the alfalfa leafcutting bee, Megachile rotundata

USDA-ARS?s Scientific Manuscript database

Megachile rotundata, the alfalfa leafcutting bee, is a solitary, cavity-nesting bee. M. rotundata develop from eggs laid inside brood cells constructed from leaf pieces and placed in series in an existing cavity. Due to the cavity nesting behavior of M. rotundata, developing bees may experience hyp...

Toward Skillful Subseasonal Prediction of North Atlantic Hurricanes with regionally-refined GFDL HiRAM

NASA Astrophysics Data System (ADS)

Gao, K.; Harris, L.; Chen, J. H.; Lin, S. J.

2017-12-01

Skillful subseasonal prediction of hurricane activity (from two weeks to less than a season) is important for early preparedness and reducing the hurricane damage in coastal regions. In this study, we will present evaluations of the performance of GFDL HiRAM (High-Resolution Atmospheric Model) for the simulation and prediction of the North Atlantic hurricane activity on the sub-seasonal time scale. A series of sub-seasonal (30-day duration) retrospective predictions were performed over the years 2000-2014 using two configurations of HiRAM: a) global uniform 25km-resolution grid and b) two-way nested grid with a 8km-resolution nest over North Atlantic. The analysis of hurricane structure from the two sets of simulations indicates the two-way-nesting method is an efficient way to improve the representation of hurricanes in global models: the two-way nested configuration produces realistic hurricane inner-core size and structure, which leads to improved lifetime maximum intensity distribution. Both configurations show very promising performance in the subseasonal hurricane genesis prediction, but the two-way nested configuration shows better performance in the prediction of major hurricane (Categories 3-5) activity because of the improved intensity simulation. We will also present the analysis of how the phase and magnitude of MJO, as well as the initial SST anomaly affect the model's prediction skill.

A Method to Represent Heterogeneous Materials for Rapid Prototyping: The Matryoshka Approach.

PubMed

Lei, Shuangyan; Frank, Matthew C; Anderson, Donald D; Brown, Thomas D

The purpose of this paper is to present a new method for representing heterogeneous materials using nested STL shells, based, in particular, on the density distributions of human bones. Nested STL shells, called Matryoshka models, are described, based on their namesake Russian nesting dolls. In this approach, polygonal models, such as STL shells, are "stacked" inside one another to represent different material regions. The Matryoshka model addresses the challenge of representing different densities and different types of bone when reverse engineering from medical images. The Matryoshka model is generated via an iterative process of thresholding the Hounsfield Unit (HU) data using computed tomography (CT), thereby delineating regions of progressively increasing bone density. These nested shells can represent regions starting with the medullary (bone marrow) canal, up through and including the outer surface of the bone. The Matryoshka approach introduced can be used to generate accurate models of heterogeneous materials in an automated fashion, avoiding the challenge of hand-creating an assembly model for input to multi-material additive or subtractive manufacturing. This paper presents a new method for describing heterogeneous materials: in this case, the density distribution in a human bone. The authors show how the Matryoshka model can be used to plan harvesting locations for creating custom rapid allograft bone implants from donor bone. An implementation of a proposed harvesting method is demonstrated, followed by a case study using subtractive rapid prototyping to harvest a bone implant from a human tibia surrogate.

An iterative method for tri-level quadratic fractional programming problems using fuzzy goal programming approach

NASA Astrophysics Data System (ADS)

Kassa, Semu Mitiku; Tsegay, Teklay Hailay

2017-08-01

Tri-level optimization problems are optimization problems with three nested hierarchical structures, where in most cases conflicting objectives are set at each level of hierarchy. Such problems are common in management, engineering designs and in decision making situations in general, and are known to be strongly NP-hard. Existing solution methods lack universality in solving these types of problems. In this paper, we investigate a tri-level programming problem with quadratic fractional objective functions at each of the three levels. A solution algorithm has been proposed by applying fuzzy goal programming approach and by reformulating the fractional constraints to equivalent but non-fractional non-linear constraints. Based on the transformed formulation, an iterative procedure is developed that can yield a satisfactory solution to the tri-level problem. The numerical results on various illustrative examples demonstrated that the proposed algorithm is very much promising and it can also be used to solve larger-sized as well as n-level problems of similar structure.

Estimating length of avian incubation and nestling stages in afrotropical forest birds from interval-censored nest records

USGS Publications Warehouse

Stanley, T.R.; Newmark, W.D.

2010-01-01

In the East Usambara Mountains in northeast Tanzania, research on the effects of forest fragmentation and disturbance on nest survival in understory birds resulted in the accumulation of 1,002 nest records between 2003 and 2008 for 8 poorly studied species. Because information on the length of the incubation and nestling stages in these species is nonexistent or sparse, our objectives in this study were (1) to estimate the length of the incubation and nestling stage and (2) to compute nest survival using these estimates in combination with calculated daily survival probability. Because our data were interval censored, we developed and applied two new statistical methods to estimate stage length. In the 8 species studied, the incubation stage lasted 9.6-21.8 days and the nestling stage 13.9-21.2 days. Combining these results with estimates of daily survival probability, we found that nest survival ranged from 6.0% to 12.5%. We conclude that our methodology for estimating stage lengths from interval-censored nest records is a reasonable and practical approach in the presence of interval-censored data. ?? 2010 The American Ornithologists' Union.

Physical activity promotion in general practice--patient attitudes.

PubMed

Elley, Carolyn Raina; Dean, Sarah; Kerse, Ngaire

2007-12-01

Long term adherence to primary care physical activity intervention is poor. This study explored attitudes and subjective experiences of those who received such an intervention. Nested qualitative study within mixed methods approach, involving 15 sedentary adults from urban and rural general practices in New Zealand. Semistructured telephone interviews were conducted, transcribed, and analysed using an inductive approach to identify themes. Four themes emerged including: tailoring of advice given; barriers to physical activity such as weather, physical environment, time, health and psychological limitations; internal motivators such as immediate or long term psychological, health or spiritual benefits, commitment, and guilt; and the role of significant others such as health and exercise professionals in initiating advice and continuing support, social interaction and commitment or contracts made to others. This study highlights the need for a personalised approach, continued structured external support and the need to focus on barriers and facilitators.

On the mound of Macrotermes michaelseni as an organ of respiratory gas exchange.

PubMed

Turner, J S

2001-01-01

Patterns and rates of air movements in the mounds and nests of Macrotermes michaelseni were studied using tracer methods. Wind is a significant source of energy for powering nest ventilation, despite the mound being a completely enclosed structure. Nests are ventilated by a tidal movement of air driven by temporal variation in wind speed and wind direction. Density gradients sufficiently steep to drive bulk flow by natural convection will be rare. However, metabolism-induced buoyant forces may interact with wind energy in a way that promotes homeostasis of the mound atmosphere.

Cooperation, competition and goal interdependence in work teams: a multilevel approach.

PubMed

Aritzeta, Aitor; Balluerka, Nekane

2006-11-01

The aim of this research was to predict cooperative and competitive conflict management styles in 26 new start-up work teams (time 1), and after one year of functioning (time 2) in an automotive company. Vertical-horizontal, individualism-collectivism cultural patterns were used as predictive variables. It was predicted that goal interdependence would moderate the relationship between cultural patterns and conflict management styles. Because of the hierarchically nested data structure, a Multilevel Analysis approach was used. Horizontal and vertical collectivism increased cooperation, and horizontal and vertical individualism increased competition. Only when work teams had been functioning for a year, goal interdependence increased cooperation and interaction effects between goal interdependence and vertical types of individualism and collectivism were observed. Implications for team-building as organizational transformational strategies are discussed.

Local Individual Preferences for Nest Materials in a Passerine Bird

PubMed Central

Mennerat, Adèle; Perret, Philippe; Lambrechts, Marcel M.

2009-01-01

Background Variation in the behavioural repertoire of animals is acquired by learning in a range of animal species. In nest-building birds, the assemblage of nest materials in an appropriate structure is often typical of a bird genus or species. Yet plasticity in the selection of nest materials may be beneficial because the nature and abundance of nest materials vary across habitats. Such plasticity can be learned, either individually or socially. In Corsican populations of blue tits Cyanistes caeruleus, females regularly add in their nests fragments of several species of aromatic plants during the whole breeding period. The selected plants represent a small fraction of the species present in the environment and have positive effects on nestlings. Methodology/Principal Findings We investigated spatiotemporal variations of this behaviour to test whether the aromatic plant species composition in nests depends on 1) plant availability in territories, 2) female experience or 3) female identity. Our results indicate that territory plays a very marginal role in the aromatic plant species composition of nests. Female experience is not related to a change in nest plant composition. Actually, this composition clearly depends on female identity, i.e. results from individual preferences which, furthermore, are repeatable both within and across years. A puzzling fact is the strong difference in plant species composition of nests across distinct study plots. Conclusions/Significance This study demonstrates that plant species composition of nests results from individual preferences that are homogeneous within study plots. We propose several hypotheses to interpret this pattern of spatial variation before discussing them in the light of preliminary results. As a conclusion, we cannot exclude the possibility of social transmission of individual preferences for aromatic plants. This is an exciting perspective for further work in birds, where nest construction behaviour has classically been considered as a stereotypic behaviour. PMID:19337365

Artificial nest predation in hedgerows and scrub forest in a human-dominated landscape of central Mexico

NASA Astrophysics Data System (ADS)

Zuria, Iriana; Gates, J. Edward; Castellanos, Ignacio

2007-03-01

Hedgerows as well as other narrow corridors could be valuable habitats for birds in regions of intensive agriculture, however, it is still not clear how successful breeding birds are in different types of hedgerows as compared to birds nesting in their natural habitats. We used artificial nests to examine whether hedgerows were sinks (ecological traps) for birds by comparing rates of predation in two types of hedgerows with different vegetation structure (simple and complex), and in a tract of scrub forest in an agricultural landscape of central Mexico. We determined also the types of predators responsible for egg predation. Ground and elevated nests were baited with one Japanese quail Coturnix japonica egg and one plasticine egg and placed alternately along transects. Significantly, greater predation rates were found in scrub forest and complex hedgerows than in simple hedgerows. Higher predation rates in complex habitats seemed to reflect the higher number of predator types found there. The most important predator types were carnivores followed by rodents, birds, and humans. Carnivores and rodents mainly predated ground nests, whereas birds and humans predated elevated nests. Simple hedgerows in this landscape appeared to offer relatively safe nest sites in terms of predation pressure when compared to more complex habitats (complex hedgerows and scrub forest).

Inter-assemblage facilitation: the functional diversity of cavity-producing beetles drives the size diversity of cavity-nesting bees.

PubMed

Sydenham, Markus A K; Häusler, Lise D; Moe, Stein R; Eldegard, Katrine

2016-01-01

Inter-specific interactions are important drivers and maintainers of biodiversity. Compared to trophic and competitive interactions, the role of non-trophic facilitation among species has received less attention. Cavity-nesting bees nest in old beetle borings in dead wood, with restricted diameters corresponding to the body size of the bee species. The aim of this study was to test the hypothesis that the functional diversity of cavity-producing wood boring beetles - in terms of cavity diameters - drives the size diversity of cavity-nesting bees. The invertebrate communities were sampled in 30 sites, located in forested landscapes along an elevational gradient. We regressed the species richness and abundance of cavity nesting bees against the species richness and abundance of wood boring beetles, non-wood boring beetles and elevation. The proportion of cavity nesting bees in bee species assemblage was regressed against the species richness and abundance of wood boring beetles. We also tested the relationships between the size diversity of cavity nesting bees and wood boring beetles. The species richness and abundance of cavity nesting bees increased with the species richness and abundance of wood boring beetles. No such relationship was found for non-wood boring beetles. The abundance of wood boring beetles was also related to an increased proportion of cavity nesting bee individuals. Moreover, the size diversity of cavity-nesting bees increased with the functional diversity of wood boring beetles. Specifically, the mean and dispersion of bee body sizes increased with the functional dispersion of large wood boring beetles. The positive relationships between cavity producing bees and cavity nesting bees suggest that non-trophic facilitative interactions between species assemblages play important roles in organizing bee species assemblages. Considering a community-wide approach may therefore be required if we are to successfully understand and conserve wild bee species assemblages in forested landscapes.

High-resolution angle-resolved photoemission study of electronic structure and charge-density wave formation in HoTe3

NASA Astrophysics Data System (ADS)

Liu, Guodong; Wang, Chenlu; Zhang, Yan; Hu, Bingfeng; Mou, Daixiang; Yu, Li; Zhao, Lin; Zhou, Xingjiang; Wang, Nanlin; Chen, Chuangtian; Xu, Zuyan

We performed high-resolution angle-resolved photoemission spectroscopy (ARPES) measurement on high quality crystal of HoTe3, an intriguing quasi-two-dimensional rare-earth-element tritelluride charge-density-wave (CDW) compound. The main features of the electronic structure in this compound are established by employing a quasi-CW laser (7eV) and a helium discharging lamp (21.22 eV) as excitation light sources. It reveals many bands back folded according to the CDW periodicity and two incommensurate CDW gaps created by perpendicular Fermi surface (FS) nesting vectors. A large gap is found to open in well nested regions of the Fermi surface sheets, whereas other Fermi surface sections with poor nesting remain ungapped. In particular, some peculiar features are identified by using our ultra-high resolution and bulk sensitive laser-ARPES.

[Nesting habitat characterization for Amazona oratrix (Psittaciformes: Psittacidae) in the Central Pacific, Mexico].

PubMed

Monterrubio-Rico, Tiberio C; Álvarez-Jara, Margarito; Tellez-Garcia, Loreno; Tena-Morelos, Carlos

2014-09-01

The nesting requirements of the Yellow-headed Parrot (Amazona oratrix) are poorly understood, despite their broad historical distribution, high demand for pet trade and current endangered status. Information concerning their nesting requirements is required in order to design specific restoration and conser- vation actions. To assess this, we studied their nesting ecology in the Central Pacific, Michoacan, Mexico during a ten year period. The analyzed variables ranged from local scale nest site characteristics such as nesting tree species, dimensions, geographic positions, diet and nesting forest patches structure, to large scale features such as vegetation use and climatic variables associated to the nesting tree distributions by an ecological niche model using Maxent. We also evaluated the parrot tolerance to land management regimes, and compared the Pacific nest trees with 18 nest trees recorded in an intensively managed private ranch in Tamaulipas, Gulf of Mexico. Parrots nested in tall trees with canopy level cavities in 92 nest-trees recorded from 11 tree species. The 72.8% of nesting occurred in trees of Astronium graveolens, and Enterolobium cyclocarpum which qualified as key- stone trees. The forests where the parrots nested, presented a maximum of 54 tree species, 50% of which were identified as food source; besides, these areas also had a high abundance of trees used as food supply. The lowest number of tree species and trees to forage occurred in an active cattle ranch, whereas the highest species rich- ness was observed in areas with natural recovery. The nesting cavity entrance height from above ground of the Pacific nesting trees resulted higher than those found in the Gulf of Mexico. We hypothesize that the differences may be attributed to Parrot behavioral differences adapting to differential poaching pressure and cavity avail- ability. Nesting trees were found in six vegetation types; however the parrots preferred conserved and riparian semi-deciduous forest for nesting, with fewer nests in deciduous forest, while nesting in transformed agricultural fields was avoided. The main climatic variables associated with the potential distribution of nests were: mean temperature of wettest quarter, mean diurnal temperature range, and precipitation of wettest month. Suitable cli- matic conditions for the potential presence of nesting trees were present in 61% of the region; however, most of the area consisted of tropical deciduous forests (55.8%), while semi-deciduous tropical forests covered only 17% of the region. These results indicated the importance to conserve semi-deciduous forests as breeding habitats for the Yellow-headed Parrot, and revealed the urgent need to implement conservation and restoration actions. These should include a total ban of land use change in tropical semi-deciduous forest areas, and for selective logging of all keystone tree species; besides, we recommend the establishment of wildlife sanctuaries in important nesting areas, and a series of tropical forest restoration programs in the Central Pacific coast.

Loneliness and depression among rural empty-nest elderly adults in Liuyang, China: a cross-sectional study

PubMed Central

Wang, Guojun; Hu, Mi; Xiao, Shui-yuan; Zhou, Liang

2017-01-01

Objective To compare loneliness, depressive symptoms and major depressive episodes between empty-nest and not-empty-nest older adults in rural areas of Liuyang city, Hunan, China. Methods A cross-sectional multi-stage random cluster survey was conducted from November 2011 to April 2012 in Liuyang, China. A total of 839 rural older residents aged 60 or above completed the survey (response rate 97.6%). In line with the definition of empty nest, 25 participants who had no children were excluded from the study, while the remaining 814 elderly adults with at least one child were included for analysis. Loneliness and depressive symptoms in rural elderly parents were assessed using the short-form UCLA Loneliness Scale (ULS-6) and the Geriatric Depression Scale (GDS). Major depressive episodes were diagnosed using the Structured Clinical Interview for DSM-IV (SCID-I). Results Significant differences were found between empty-nest and not-empty-nest older adults regarding loneliness (16.19±3.90 vs. 12.87±3.02, Cohen’s d=0.97), depressive symptoms (8.50±6.26 vs. 6.92±5.19, Cohen’s d=0.28) and the prevalence of major depressive episodes (10.1% vs. 4.6%) (all p<0.05). After controlling for demographic characteristics and physical disease, the differences in loneliness, depressive symptoms and major depressive episodes remained significant. Path analysis showed that loneliness mediated the relationship between empty-nest syndrome and depressive symptoms and major depressive episodes. Conclusion Loneliness and depression are more severe among empty-nest than not-empty-nest rural elderly adults. Loneliness was a mediating variable between empty-nest syndrome and depression. PMID:28988166

Rank-based methods for modeling dependence between loss triangles.

PubMed

Côté, Marie-Pier; Genest, Christian; Abdallah, Anas

2016-01-01

In order to determine the risk capital for their aggregate portfolio, property and casualty insurance companies must fit a multivariate model to the loss triangle data relating to each of their lines of business. As an inadequate choice of dependence structure may have an undesirable effect on reserve estimation, a two-stage inference strategy is proposed in this paper to assist with model selection and validation. Generalized linear models are first fitted to the margins. Standardized residuals from these models are then linked through a copula selected and validated using rank-based methods. The approach is illustrated with data from six lines of business of a large Canadian insurance company for which two hierarchical dependence models are considered, i.e., a fully nested Archimedean copula structure and a copula-based risk aggregation model.

Variability in nest density, occupancy, and home range size of western bluebirds after forest treatments

Treesearch

Sarah Hurteau; Thomas Sisk; Brett Dickson; William Block

2010-01-01

Complex land use and fuels management histories have resulted in significant changes in composition, structure, and function of southwestern forests and subsequent changes in the extent and quality of wildlife habitats. We evaluated how several currently used fuel reduction treatments (e.g., mechanical thinning and prescribed fire alone and in combination) affect nest...

Impacts of flamingos on saline lake margin and shallow lacustrine sediments in the Kenya Rift Valley

NASA Astrophysics Data System (ADS)

Scott, Jennifer J.; Renaut, Robin W.; Owen, R. Bernhart

2012-11-01

Studies of modern, Holocene, and Pleistocene sediments around saline to hypersaline, alkaline Lake Bogoria and Lake Magadi show that evidence of flamingo activity in marginal areas of these lakes is nearly ubiquitous. Flamingos produce discrete structures such as webbed footprints (~ 9 cm long, ~ 11 cm wide) and nest mounds (~ 30 cm wide, ~ 20 cm high), and they also extensively rework sediments in delta front, delta plain, and shoreline areas. Large (~ 0.5-2 cm in diameter), pinched, 'bubble pores' and ped-like mud clumps are formed by the trampling and churning of wet clay-rich sediments in these settings. Flamingo nest mounds, although superficially similar to some thrombolite mounds, are typically internally structureless, unless formed on pre-existing sediments that preserve internal structures. The flamingo mounds consist of a dense, packed oval-shaped core, a surrounding 'body' of packed sediment, and an external layer with a ped-like texture of clumped mud. The nests may contain open holes from roots or feather shafts incorporated into the nest, and (or) burrows produced once the nests are abandoned. In areas with high densities of flamingos, lake margin sediments may be preferentially compacted, particularly at breeding sites, and become resistant to subaerial erosion and the effects of transgressive ravinement on time scales ranging from seasons to tens of thousands of years. The relatively well-compacted nest mounds and associated sediments also contribute to the stability of delta distributary channels during regressive-transgressive cycles, and can lead to the minor channelization of unconfined flows where currents are diverted around nest mounds. Pleistocene exhumed surfaces of relatively well-indurated lake margin sediments at Lake Bogoria and Lake Magadi that are interpreted as combined regressive and transgressive surfaces (flooding surface/sequence boundary) preserve evidence of flamingo activities, and are overlain by younger, porous lacustrine silts that preserve large bubble pores produced by flamingos.

Population responses to environmental change in a tropical ant: the interaction of spatial and temporal dynamics.

PubMed

Jackson, Doug; Vandermeer, John; Perfecto, Ivette; Philpott, Stacy M

2014-01-01

Spatial structure can have a profound, but often underappreciated, effect on the temporal dynamics of ecosystems. Here we report on a counterintuitive increase in the population of a tree-nesting ant, Azteca sericeasur, in response to a drastic reduction in the number of potential nesting sites. This surprising result is comprehensible when viewed in the context of the self-organized spatial dynamics of the ants and their effect on the ants' dispersal-limited natural enemies. Approximately 30% of the trees in the study site, a coffee agroecosystem in southern Mexico, were pruned or felled over a two-year period, and yet the abundance of the ant nests more than doubled over the seven-year study. Throughout the transition, the spatial distribution of the ants maintained a power-law distribution - a signal of spatial self organization - but the local clustering of the nests was reduced post-pruning. A cellular automata model incorporating the changed spatial structure of the ants and the resulting partial escape from antagonists reproduced the observed increase in abundance, highlighting how self-organized spatial dynamics can profoundly influence the responses of ecosystems to perturbations.

Population Responses to Environmental Change in a Tropical Ant: The Interaction of Spatial and Temporal Dynamics

PubMed Central

Jackson, Doug; Vandermeer, John; Perfecto, Ivette; Philpott, Stacy M.

2014-01-01

Spatial structure can have a profound, but often underappreciated, effect on the temporal dynamics of ecosystems. Here we report on a counterintuitive increase in the population of a tree-nesting ant, Azteca sericeasur, in response to a drastic reduction in the number of potential nesting sites. This surprising result is comprehensible when viewed in the context of the self-organized spatial dynamics of the ants and their effect on the ants’ dispersal-limited natural enemies. Approximately 30% of the trees in the study site, a coffee agroecosystem in southern Mexico, were pruned or felled over a two-year period, and yet the abundance of the ant nests more than doubled over the seven-year study. Throughout the transition, the spatial distribution of the ants maintained a power-law distribution – a signal of spatial self organization – but the local clustering of the nests was reduced post-pruning. A cellular automata model incorporating the changed spatial structure of the ants and the resulting partial escape from antagonists reproduced the observed increase in abundance, highlighting how self-organized spatial dynamics can profoundly influence the responses of ecosystems to perturbations. PMID:24842117

Optimizing dynamic downscaling in one-way nesting using a regional ocean model

NASA Astrophysics Data System (ADS)

Pham, Van Sy; Hwang, Jin Hwan; Ku, Hyeyun

2016-10-01

Dynamical downscaling with nested regional oceanographic models has been demonstrated to be an effective approach for both operationally forecasted sea weather on regional scales and projections of future climate change and its impact on the ocean. However, when nesting procedures are carried out in dynamic downscaling from a larger-scale model or set of observations to a smaller scale, errors are unavoidable due to the differences in grid sizes and updating intervals. The present work assesses the impact of errors produced by nesting procedures on the downscaled results from Ocean Regional Circulation Models (ORCMs). Errors are identified and evaluated based on their sources and characteristics by employing the Big-Brother Experiment (BBE). The BBE uses the same model to produce both nesting and nested simulations; so it addresses those error sources separately (i.e., without combining the contributions of errors from different sources). Here, we focus on discussing errors resulting from the spatial grids' differences, the updating times and the domain sizes. After the BBE was separately run for diverse cases, a Taylor diagram was used to analyze the results and recommend an optimal combination of grid size, updating period and domain sizes. Finally, suggested setups for the downscaling were evaluated by examining the spatial correlations of variables and the relative magnitudes of variances between the nested model and the original data.

Host selection by the shiny cowbird

USGS Publications Warehouse

Wiley, J.W.

1988-01-01

Factors important in Shiny Cowbird (Molothrus bonariensis) host selection were examined within the mangrove community in Puerto Rico. Cowbirds did not parasitize birds in proportion to their abundance. The cowbird breeding season coincided with those of its major hosts, which were 'high-quality' foster species (i.e., species that fledge .gtoreq. 55% of cowbirds hatched: Yellow Warbler, Dendroica petechia; Yellow-shouldered Blackbird, Agelaius xanthomus; Black-whiskered Vireo, Vireo altiloquus; Black-cowled Oriole, Icterus dominicensis; Peurto Rican Flycatcher, Myiarchus antillarum; Troupial, Icterus icterus), and did not extend into other periods even though nests of 'low-quality: species (i.e., species that fledge < 55% of cowbird chicks that hatched: Bronze Mannikin, Lonchura cucullata; Greater Antillean Grackle, Quiscalus niger; Gray Kingbird, Tyrannus dominicensis; Northern Mockingbird, Mimus polyglottos; Red-legged Thrush, Turdus plumbeus) were available. Shiny Cowbird food habits and egg size were similar to those of their hosts, suggesting that cowbirds choose hosts partly on the basis of this combination. Cowbirds located host nests primarily by cryptically watching activities of birds in likely habitats. Other nest locating strategies were active searching of suitable habitat and 'flushing' of hosts by the cowbird's noisy approach. Cowbirds closely monitored nest status with frequent visits that peaked on the host's first day of egg laying. Hosts using covered nests (e.g., cavities, domed nests) were as vulnerable to cowbird parasitism as those building open nests.

[Duration of the pre-nesting period and its relation with social organization in sandpipers (Charadrii, Aves) nesting in north-east Yakutia].

PubMed

Gavrilov, V V

2013-01-01

Investigations were carried out at two stations of Ornithological Unit, IBPN FEB RAS, located in Nizhnekolymsk District, Yakutia, starting from May 18-20 in 1984, 1985, 1987, 1988 and 1990. Duration of the pre-nesting period in 11 sandpiper species with different social organization was studied and compared with each other by allometric equations. As a characteristic of bird size the body mass was selected. Sandpipers come flying to the tundra at almost critical temperatures, to begin breeding as early as possible. Tining of breeding depends on birds feeding manner and the proximity to sites of overwintering. Duration of the pre-nesting period is invariable for every bird species and sex. There are sexual distinctions in time spent for the pre-nesting period in jointly-nesting sandpipers. The exponents in allometric equations that relate duration of the pre-nesting period with body mass are constant within a particular sex and differ between males and females. In different sexes, time spent for the pre-nesting period depends on mating, parental, and territorial systems. In sandpipers' males and females, this time is determined by the type of social organization. Relatively large sandpiper species seek to shortening of the pre-nesting period calendar time, which constrains their social organization. Monogamy and pair parental care lead to a necessity for spatial population structure to be controlled more strictly and maintained for a longer time. This, in turn, causes the increasing of males' time expenditures for such a behavior.

Dissecting protein loops with a statistical scalpel suggests a functional implication of some structural motifs.

PubMed

Regad, Leslie; Martin, Juliette; Camproux, Anne-Claude

2011-06-20

One of the strategies for protein function annotation is to search particular structural motifs that are known to be shared by proteins with a given function. Here, we present a systematic extraction of structural motifs of seven residues from protein loops and we explore their correspondence with functional sites. Our approach is based on the structural alphabet HMM-SA (Hidden Markov Model - Structural Alphabet), which allows simplification of protein structures into uni-dimensional sequences, and advanced pattern statistics adapted to short sequences. Structural motifs of interest are selected by looking for structural motifs significantly over-represented in SCOP superfamilies in protein loops. We discovered two types of structural motifs significantly over-represented in SCOP superfamilies: (i) ubiquitous motifs, shared by several superfamilies and (ii) superfamily-specific motifs, over-represented in few superfamilies. A comparison of ubiquitous words with known small structural motifs shows that they contain well-described motifs as turn, niche or nest motifs. A comparison between superfamily-specific motifs and biological annotations of Swiss-Prot reveals that some of them actually correspond to functional sites involved in the binding sites of small ligands, such as ATP/GTP, NAD(P) and SAH/SAM. Our findings show that statistical over-representation in SCOP superfamilies is linked to functional features. The detection of over-represented motifs within structures simplified by HMM-SA is therefore a promising approach for prediction of functional sites and annotation of uncharacterized proteins.

Dissecting protein loops with a statistical scalpel suggests a functional implication of some structural motifs

PubMed Central

2011-01-01

Background One of the strategies for protein function annotation is to search particular structural motifs that are known to be shared by proteins with a given function. Results Here, we present a systematic extraction of structural motifs of seven residues from protein loops and we explore their correspondence with functional sites. Our approach is based on the structural alphabet HMM-SA (Hidden Markov Model - Structural Alphabet), which allows simplification of protein structures into uni-dimensional sequences, and advanced pattern statistics adapted to short sequences. Structural motifs of interest are selected by looking for structural motifs significantly over-represented in SCOP superfamilies in protein loops. We discovered two types of structural motifs significantly over-represented in SCOP superfamilies: (i) ubiquitous motifs, shared by several superfamilies and (ii) superfamily-specific motifs, over-represented in few superfamilies. A comparison of ubiquitous words with known small structural motifs shows that they contain well-described motifs as turn, niche or nest motifs. A comparison between superfamily-specific motifs and biological annotations of Swiss-Prot reveals that some of them actually correspond to functional sites involved in the binding sites of small ligands, such as ATP/GTP, NAD(P) and SAH/SAM. Conclusions Our findings show that statistical over-representation in SCOP superfamilies is linked to functional features. The detection of over-represented motifs within structures simplified by HMM-SA is therefore a promising approach for prediction of functional sites and annotation of uncharacterized proteins. PMID:21689388

Origin and Loss of Nested LRRTM/α-Catenin Genes during Vertebrate Evolution

PubMed Central

Uvarov, Pavel; Kajander, Tommi; Airaksinen, Matti S.

2014-01-01

Leucine-rich repeat transmembrane neuronal proteins (LRRTMs) form in mammals a family of four postsynaptic adhesion proteins, which have been shown to bind neurexins and heparan sulphate proteoglycan (HSPG) glypican on the presynaptic side. Mutations in the genes encoding LRRTMs and neurexins are implicated in human cognitive disorders such as schizophrenia and autism. Our analysis shows that in most jawed vertebrates, lrrtm1, lrrtm2, and lrrtm3 genes are nested on opposite strands of large conserved intron of α-catenin genes ctnna2, ctnna1, and ctnna3, respectively. No lrrtm genes could be found in tunicates or lancelets, while two lrrtm genes are found in the lamprey genome, one of which is adjacent to a single ctnna homolog. Based on similar highly positive net charge of lamprey LRRTMs and the HSPG-binding LRRTM3 and LRRTM4 proteins, we speculate that the ancestral LRRTM might have bound HSPG before acquiring neurexins as binding partners. Our model suggests that lrrtm gene translocated into the large ctnna intron in early vertebrates, and that subsequent duplications resulted in three lrrtm/ctnna gene pairs present in most jawed vertebrates. However, we detected three prominent exceptions: (1) the lrrtm3/ctnna3 gene structure is absent in the ray-finned fish genomes, (2) the genomes of clawed frogs contain ctnna1 but lack the corresponding nested (lrrtm2) gene, and (3) contain lrrtm3 gene in the syntenic position but lack the corresponding host (ctnna3) gene. We identified several other protein-coding nested gene structures of which either the host or the nested gene has presumably been lost in the frog or chicken lineages. Interestingly, majority of these nested genes comprise LRR domains. PMID:24587117

Managing American Oystercatcher (Haematopus palliatus) population qrowth by targeting nesting season vital rates

USGS Publications Warehouse

Felton, Shilo K.; Hostetter, Nathan J.; Pollock, Kenneth H.; Simons, Theodore R.

2017-01-01

In populations of long-lived species, adult survival typically has a relatively high influence on population growth. From a management perspective, however, adult survival can be difficult to increase in some instances, so other component rates must be considered to reverse population declines. In North Carolina, USA, management to conserve the American Oystercatcher (Haematopus palliatus) targets component vital rates related to fecundity, specifically nest and chick survival. The effectiveness of such a management approach in North Carolina was assessed by creating a three-stage female-based deterministic matrix model. Isoclines were produced from the matrix model to evaluate minimum nest and chick survival rates necessary to reverse population decline, assuming all other vital rates remained stable at mean values. Assuming accurate vital rates, breeding populations within North Carolina appear to be declining. To reverse this decline, combined nest and chick survival would need to increase from 0.14 to ≤ 0.27, a rate that appears to be attainable based on historical estimates. Results are heavily dependent on assumptions of other vital rates, most notably adult survival, revealing the need for accurate estimates of all vital rates to inform management actions. This approach provides valuable insights for evaluating conservation goals for species of concern.

Analyzing medical costs with time-dependent treatment: The nested g-formula.

PubMed

Spieker, Andrew; Roy, Jason; Mitra, Nandita

2018-04-16

As medical expenses continue to rise, methods to properly analyze cost outcomes are becoming of increasing relevance when seeking to compare average costs across treatments. Inverse probability weighted regression models have been developed to address the challenge of cost censoring in order to identify intent-to-treat effects (i.e., to compare mean costs between groups on the basis of their initial treatment assignment, irrespective of any subsequent changes to their treatment status). In this paper, we describe a nested g-computation procedure that can be used to compare mean costs between two or more time-varying treatment regimes. We highlight the relative advantages and limitations of this approach when compared with existing regression-based models. We illustrate the utility of this approach as a means to inform public policy by applying it to a simulated data example motivated by costs associated with cancer treatments. Simulations confirm that inference regarding intent-to-treat effects versus the joint causal effects estimated by the nested g-formula can lead to markedly different conclusions regarding differential costs. Therefore, it is essential to prespecify the desired target of inference when choosing between these two frameworks. The nested g-formula should be considered as a useful, complementary tool to existing methods when analyzing cost outcomes. Copyright © 2018 John Wiley & Sons, Ltd.

A Bioinformatics Approach for Detecting Repetitive Nested Motifs using Pattern Matching.

PubMed

Romero, José R; Carballido, Jessica A; Garbus, Ingrid; Echenique, Viviana C; Ponzoni, Ignacio

2016-01-01

The identification of nested motifs in genomic sequences is a complex computational problem. The detection of these patterns is important to allow the discovery of transposable element (TE) insertions, incomplete reverse transcripts, deletions, and/or mutations. In this study, a de novo strategy for detecting patterns that represent nested motifs was designed based on exhaustive searches for pairs of motifs and combinatorial pattern analysis. These patterns can be grouped into three categories, motifs within other motifs, motifs flanked by other motifs, and motifs of large size. The methodology used in this study, applied to genomic sequences from the plant species Aegilops tauschii and Oryza sativa , revealed that it is possible to identify putative nested TEs by detecting these three types of patterns. The results were validated through BLAST alignments, which revealed the efficacy and usefulness of the new method, which is called Mamushka.

Relationships of environmental contaminants to reproductive success in red-breasted mergansers (Mergus serrator) from Lake Michigan

USGS Publications Warehouse

Heinz, G.H.; Haseltine, S.D.; Reichel, W.L.; Hensler, G.L.

1983-01-01

In 1977 and 1978, we studied red-breasted mergansers Mergus serrator nesting on islands in northwestern Lake Michigan to determine whether environmental contaminants were having effects on reproduction. Seventeen contaminants were measured in randomly chosen eggs from 206 nests under study. Using a variety of statistical approaches, we looked for effects of individual contaminants and combinations of contaminants on reproductive measurements such as nest desertion, failure of eggs to hatch, death of newly hatched ducklings, percentage hatching success, number of ducklings leaving the nest and eggshell thickness. We also looked for relationships between the levels of some contaminants in blood samples of 39 incubating females and reproductive success. A small degree of eggshell thinning was attributed to DDE and a few other statistical tests were significant, but no contaminant or combination of contaminants we measured seemed to have a pronounced effect on the aspects of reproduction we followed.

Edge, height and visibility effects on nest predation by birds and mammals in the Brazilian cerrado

NASA Astrophysics Data System (ADS)

Dodonov, Pavel; Paneczko, Ingrid Toledo; Telles, Marina

2017-08-01

Edge influence is one of the main impacts in fragmented landscapes; yet, most of studies on edge influence have focused on high-contrast edges, and the impacts of low-contrast edges and narrow linear openings are less understood. Edge influence often affects bird nest predation, but these effects are not ubiquitous and may depend on characteristics such as nest height and visibility. We performed an experiment on nest predation in a migratory passerine, Elaenia chiriquensis (Lesser Elaenia; Passeriformes: Tyrannidae), in a savanna vegetation of the Brazilian Cerrado biome in South-Eastern Brazil. We used 89 real E. chiriquensis nests, collected during previous reproductive seasons, with two plasticine eggs in each, and randomly distributed them at two locations (edge - up to 20 m from a firebreak edge and interior - approx. 150-350 m from the edge) and two heights (low - 60-175 cm and high - 190-315 cm above ground). We also measured leaf and branch density around each nest. We performed this study on two 15-days campaigns, checking the nests every 2-3 days and removing those with predation marks. We sorted the predation marks into those made by birds, mammals, or unidentified predators, and used generalized linear models to assess the effects of location, height and leaf density on survival time and predator type. Only four nests had not been predated during the experiment; 55 nests were predated by birds, 7 by mammals, and 23 by unidentified predators. Low nests in the interior tended to have larger survival times whereas high nests at the edge tended to be more predated by birds and less predated by mammals. Thus, even a low-contrast (firebreak) edge may significantly increase nest predation, which is also affected by the nest's height, mainly due to predation by birds. These effects may be due to predator movement along the edge as well as to edge-related changes in vegetation structure. We suggest that higher-contrast edges which may also be used as movement conduits, for example powerline openings, may have even stronger effects, demanding further studies.

Reproductive ecology of American Oystercatchers nesting on shell rakes

USGS Publications Warehouse

Jodice, Patrick G.R.; Thibault, Janet M.; Collins, S.A.; Spinks, Mark D.; Sanders, Felicia J.

2014-01-01

Degradation of nesting habitat for coastal birds has led to the use of nontraditional nesting habitat. The American Oystercatcher (Haematopus palliatus) is listed as a "Species of High Concern'' by the U. S. Shorebird Conservation Plan and is declining in the southern portion of its U. S. breeding range, where ~ 50% of breeding oystercatchers nest on shell substrate instead of beachfront habitat. We measured daily survival rates during incubation and chick rearing in shell rake habitats over five breeding seasons in the Cape Romain region of South Carolina, USA. Of 354 nesting attempts monitored, 16.1% hatched at least one egg. During incubation, daily survival rate was 0.938, corresponding to 22.8% success to hatching (nest success). For broods, daily survival was 0.991, or 74.0% success from hatching to fledging. Productivity in the Cape Romain region is primarily being lost during the incubation phase, when nests are exposed to overwash and predation. Mobile chicks may, however, be able to avoid flood events or predators by relocating to higher or more protected portions of a shell rake. Based on comparative data for American Oystercatchers from elsewhere in their range, it does not appear that shell rakes in the Cape Romain region are inferior breeding habitat. Our data suggest that conservation actions targeting nest and chick loss from flooding and predation have the greatest opportunity to enhance reproductive success in this core breeding area, and that an assessment of the availability, structure, avian use, and protection status of shell rakes is warranted.

Nest site preferences of the Woodlark (Lullula arborea) and its association with artificial nest predation

NASA Astrophysics Data System (ADS)

Buehler, Roman; Bosco, Laura; Arlettaz, Raphaël; Jacot, Alain

2017-01-01

The Woodlark is an insectivorous bird, which is listed as a priority species in Switzerland. In Valais, a stronghold of this species in the country, the birds breed in intensively managed vineyards and show a preference for parcels with ground vegetation during territory establishment. As a ground-breeder, the species is highly vulnerable to nest predation by avian and mammal predators. The aims of our study were firstly to investigate nest site preferences of the woodlark within vineyards and secondly to compare the predation risk of artificial nests dependent of ground vegetation structure. Our results point out that the Woodlark prefers patches of tall and dense ground cover within vegetated vineyard parcels and avoids parcels that have been treated with herbicides. In a follow-up experiment we conducted a study comparing the predation rate of artificial nests between bare parcels (<20% vegetated area) and vegetated parcels (>40% vegetated area). Artificial nests equipped with one quail egg were distributed pairwise between two adjacent parcels that fulfilled the upper criteria and were monitored by trail cameras during 10-12 days. Predation rate was generally low (4 predation events) and only occurred in bare parcels. These data indicate that conspicuousness of avian nests may be decreased in vegetated parcels and that the amount of vegetation can lower the predation risk on ground breeding birds - another indication for the importance of ground vegetation for a successful conservation of the endangered Woodlark in Swiss vineyards.

A large accumulation of avian eggs from the late cretaceous of patagonia (Argentina) reveals a novel nesting strategy in mesozoic birds.

PubMed

Fernández, Mariela S; García, Rodolfo A; Fiorelli, Lucas; Scolaro, Alejandro; Salvador, Rodrigo B; Cotaro, Carlos N; Kaiser, Gary W; Dyke, Gareth J

2013-01-01

We report the first evidence for a nesting colony of mesozoic birds on Gondwana: a fossil accumulation in Late Cretaceous rocks mapped and collected from within the campus of the National University of Comahue, Neuquén City, Patagonia (Argentina). Here, Cretaceous ornithothoracine birds, almost certainly Enanthiornithes, nested in an arid, shallow basinal environment among sand dunes close to an ephemeral water-course. We mapped and collected 65 complete, near-complete, and broken eggs across an area of more than 55 m(2). These eggs were laid either singly, or occasionally in pairs, onto a sandy substrate. All eggs were found apparently in, or close to, their original nest site; they all occur within the same bedding plane and may represent the product of a single nesting season or a short series of nesting attempts. Although there is no evidence for nesting structures, all but one of the Comahue eggs were half-buried upright in the sand with their pointed end downwards, a position that would have exposed the pole containing the air cell and precluded egg turning. This egg position is not seen in living birds, with the exception of the basal galliform megapodes who place their eggs within mounds of vegetation or burrows. This accumulation reveals a novel nesting behaviour in Mesozoic Aves that was perhaps shared with the non-avian and phylogenetically more basal troodontid theropods.

A Large Accumulation of Avian Eggs from the Late Cretaceous of Patagonia (Argentina) Reveals a Novel Nesting Strategy in Mesozoic Birds

PubMed Central

Fernández, Mariela S.; García, Rodolfo A.; Fiorelli, Lucas; Scolaro, Alejandro; Salvador, Rodrigo B.; Cotaro, Carlos N.; Kaiser, Gary W.; Dyke, Gareth J.

2013-01-01

We report the first evidence for a nesting colony of Mesozoic birds on Gondwana: a fossil accumulation in Late Cretaceous rocks mapped and collected from within the campus of the National University of Comahue, Neuquén City, Patagonia (Argentina). Here, Cretaceous ornithothoracine birds, almost certainly Enanthiornithes, nested in an arid, shallow basinal environment among sand dunes close to an ephemeral water-course. We mapped and collected 65 complete, near-complete, and broken eggs across an area of more than 55 m2. These eggs were laid either singly, or occasionally in pairs, onto a sandy substrate. All eggs were found apparently in, or close to, their original nest site; they all occur within the same bedding plane and may represent the product of a single nesting season or a short series of nesting attempts. Although there is no evidence for nesting structures, all but one of the Comahue eggs were half-buried upright in the sand with their pointed end downwards, a position that would have exposed the pole containing the air cell and precluded egg turning. This egg position is not seen in living birds, with the exception of the basal galliform megapodes who place their eggs within mounds of vegetation or burrows. This accumulation reveals a novel nesting behaviour in Mesozoic Aves that was perhaps shared with the non-avian and phylogenetically more basal troodontid theropods. PMID:23613776

Predicting bycatch hotspots for endangered leatherback turtles on longlines in the Pacific Ocean.

PubMed

Roe, John H; Morreale, Stephen J; Paladino, Frank V; Shillinger, George L; Benson, Scott R; Eckert, Scott A; Bailey, Helen; Tomillo, Pilar Santidrián; Bograd, Steven J; Eguchi, Tomoharu; Dutton, Peter H; Seminoff, Jeffrey A; Block, Barbara A; Spotila, James R

2014-02-22

Fisheries bycatch is a critical source of mortality for rapidly declining populations of leatherback turtles, Dermochelys coriacea. We integrated use-intensity distributions for 135 satellite-tracked adult turtles with longline fishing effort to estimate predicted bycatch risk over space and time in the Pacific Ocean. Areas of predicted bycatch risk did not overlap for eastern and western Pacific nesting populations, warranting their consideration as distinct management units with respect to fisheries bycatch. For western Pacific nesting populations, we identified several areas of high risk in the north and central Pacific, but greatest risk was adjacent to primary nesting beaches in tropical seas of Indo-Pacific islands, largely confined to several exclusive economic zones under the jurisdiction of national authorities. For eastern Pacific nesting populations, we identified moderate risk associated with migrations to nesting beaches, but the greatest risk was in the South Pacific Gyre, a broad pelagic zone outside national waters where management is currently lacking and may prove difficult to implement. Efforts should focus on these predicted hotspots to develop more targeted management approaches to alleviate leatherback bycatch.

Predicting bycatch hotspots for endangered leatherback turtles on longlines in the Pacific Ocean

PubMed Central

Roe, John H.; Morreale, Stephen J.; Paladino, Frank V.; Shillinger, George L.; Benson, Scott R.; Eckert, Scott A.; Bailey, Helen; Tomillo, Pilar Santidrián; Bograd, Steven J.; Eguchi, Tomoharu; Dutton, Peter H.; Seminoff, Jeffrey A.; Block, Barbara A.; Spotila, James R.

2014-01-01

Fisheries bycatch is a critical source of mortality for rapidly declining populations of leatherback turtles, Dermochelys coriacea. We integrated use-intensity distributions for 135 satellite-tracked adult turtles with longline fishing effort to estimate predicted bycatch risk over space and time in the Pacific Ocean. Areas of predicted bycatch risk did not overlap for eastern and western Pacific nesting populations, warranting their consideration as distinct management units with respect to fisheries bycatch. For western Pacific nesting populations, we identified several areas of high risk in the north and central Pacific, but greatest risk was adjacent to primary nesting beaches in tropical seas of Indo-Pacific islands, largely confined to several exclusive economic zones under the jurisdiction of national authorities. For eastern Pacific nesting populations, we identified moderate risk associated with migrations to nesting beaches, but the greatest risk was in the South Pacific Gyre, a broad pelagic zone outside national waters where management is currently lacking and may prove difficult to implement. Efforts should focus on these predicted hotspots to develop more targeted management approaches to alleviate leatherback bycatch. PMID:24403331

Mapping the navigational knowledge of individually foraging ants, Myrmecia croslandi

PubMed Central

Narendra, Ajay; Gourmaud, Sarah; Zeil, Jochen

2013-01-01

Ants are efficient navigators, guided by path integration and visual landmarks. Path integration is the primary strategy in landmark-poor habitats, but landmarks are readily used when available. The landmark panorama provides reliable information about heading direction, routes and specific location. Visual memories for guidance are often acquired along routes or near to significant places. Over what area can such locally acquired memories provide information for reaching a place? This question is unusually approachable in the solitary foraging Australian jack jumper ant, since individual foragers typically travel to one or two nest-specific foraging trees. We find that within 10 m from the nest, ants both with and without home vector information available from path integration return directly to the nest from all compass directions, after briefly scanning the panorama. By reconstructing panoramic views within the successful homing range, we show that in the open woodland habitat of these ants, snapshot memories acquired close to the nest provide sufficient navigational information to determine nest-directed heading direction over a surprisingly large area, including areas that animals may have not visited previously. PMID:23804615

A critical evaluation of various methods for the analysis of flow-solid interaction in a nest of thin cylinders subjected to cross flows

NASA Technical Reports Server (NTRS)

Kim, Sang-Wook

1987-01-01

Various experimental, analytical, and numerical analysis methods for flow-solid interaction of a nest of cylinders subjected to cross flows are reviewed. A nest of cylinders subjected to cross flows can be found in numerous engineering applications including the Space Shuttle Maine Engine-Main Injector Assembly (SSME-MIA) and nuclear reactor heat exchangers. Despite its extreme importance in engineering applications, understanding of the flow-solid interaction process is quite limited and design of the tube banks are mostly dependent on experiments and/or experimental correlation equations. For future development of major numerical analysis methods for the flow-solid interaction of a nest of cylinders subjected to cross flow, various turbulence models, nonlinear structural dynamics, and existing laminar flow-solid interaction analysis methods are included.

A mesh-free approach to acoustic scattering from multiple spheres nested inside a large sphere by using diagonal translation operators.

PubMed

Hesford, Andrew J; Astheimer, Jeffrey P; Greengard, Leslie F; Waag, Robert C

2010-02-01

A multiple-scattering approach is presented to compute the solution of the Helmholtz equation when a number of spherical scatterers are nested in the interior of an acoustically large enclosing sphere. The solution is represented in terms of partial-wave expansions, and a linear system of equations is derived to enforce continuity of pressure and normal particle velocity across all material interfaces. This approach yields high-order accuracy and avoids some of the difficulties encountered when using integral equations that apply to surfaces of arbitrary shape. Calculations are accelerated by using diagonal translation operators to compute the interactions between spheres when the operators are numerically stable. Numerical results are presented to demonstrate the accuracy and efficiency of the method.

A mesh-free approach to acoustic scattering from multiple spheres nested inside a large sphere by using diagonal translation operators

PubMed Central

Hesford, Andrew J.; Astheimer, Jeffrey P.; Greengard, Leslie F.; Waag, Robert C.

2010-01-01

A multiple-scattering approach is presented to compute the solution of the Helmholtz equation when a number of spherical scatterers are nested in the interior of an acoustically large enclosing sphere. The solution is represented in terms of partial-wave expansions, and a linear system of equations is derived to enforce continuity of pressure and normal particle velocity across all material interfaces. This approach yields high-order accuracy and avoids some of the difficulties encountered when using integral equations that apply to surfaces of arbitrary shape. Calculations are accelerated by using diagonal translation operators to compute the interactions between spheres when the operators are numerically stable. Numerical results are presented to demonstrate the accuracy and efficiency of the method. PMID:20136208

Conceptualizing and Confronting Inequity: Approaches within and New Directions for the "NNEST Movement"

ERIC Educational Resources Information Center

Rudolph, Nathanael; Selvi, Ali Fuad; Yazan, Bedrettin

2015-01-01

This article examines inequity as conceptualized and approached within and through the non-native English speakers in TESOL (NNEST) "movement." The authors unpack critical approaches to the NNEST experience, conceptualized via binaries (NS/NNS; NEST/NNEST). The authors then explore postmodern and poststructural approaches to identity and…

Luminescence dating of anthropogenic features of the San Luis Valley, Colorado: from stone huts to stone walls

USGS Publications Warehouse

Mahan, Shannon; Donlan, Rebecca A.; Kardos, Barbara Maat

2015-01-01

The Snake Nest Wall site and the Crestone Stone Huts are in the northern San Luis Valley, Colorado, and provide a unique opportunity to date high-altitude archeological sites of unknown age and origin using optically stimulated luminescence (OSL). We sampled sediment underlying foundation stones of these structures to establish a chronological framework for each site's construction. OSL dating of the quartz grains directly under the Snake Nest Wall suggest that the stones and, therefore, the structure was most recently emplaced between 1855 and 1890 A.D. Dating of the sediment beneath the Crestone Stone Huts suggests the construction time of these huts is between 1860 and 1890 A.D. Analysis of the equivalent dose (DE) dispersion of the OSL samples at Snake Nest Wall and the Crestone Huts shows that the majority of sediments were fully bleached prior to deposition and the low scatter suggests that short-term or shallow alluvial processes were the dominant transport for sediments. In both cases, the OSL ages show that the construction was during very recent historical times, although it is likely that the Snake Nest Wall was rebuilt in the late 19th century. Further study is warranted at the Snake Nest Wall since it shows signs of greater antiquity and a continued presence of human use. The Crestone Huts are shown to be a product of railroad building during the boomtown days of Lucky and Crestone.

Demographic differences of black-capped vireos in 2 habitat types in central Texas

USGS Publications Warehouse

Noa, L.A.; Hirth, D.H.; Donovan, T.M.; Cimprich, D.

2007-01-01

To understand the effects of habitat selection, we analyzed differences in abundance, age structure, and nesting success of black-capped vireos (Vireo atricapilla) in 2 early successional habitat types found on Fort Hood, a 87,890-ha Military Reservation in central Texas, USA. These habitats were 1) large areas of continuously shrubby vegetation (both natural and mechanically made), referred to as shrubland habitat, and 2) anthropogenically created small patches of shrubby vegetation centered on one or several large trees, known locally as donut habitat. The objectives of our study were to determine whether there were differences in abundance, age structure, and daily nest survival in these 2 habitat types and to determine whether donut habitat is high- or low-quality habitat. Donut habitat had a lower abundance of vireos (half as many as shrubland/point count) and a higher percentage of second-year males, suggesting donut habitat was lower-quality habitat than shrubland. Analyses of daily nest survival indicated that habitat, nest height, and year were all important variables. Nests initiated in 2004, located in shrubland habitats, and higher from the ground were more likely to succeed. Our study provided evidence that habitat is a limiting factor for this federally endangered species. Because habitat is limiting, wildlife biologists at Fort Hood should focus on managing higher quality, contiguous shrubland habitat. Wildlife biologists should also continue to monitor areas of donut habitat to determine whether they represent potential population sinks.

Effects of leafy spurge infestation on grassland birds

USGS Publications Warehouse

Scheiman, D.M.; Bollinger, E.K.; Johnson, D.H.

2003-01-01

Grassland bird populations are declining. Invasive plant species may be contributing to these declines by altering habitat quality. However, the effects of invasive plants on grassland birds are largely unknown. Leafy spurge (Euphorbia esula) is an exotic, invasive weed in the northern Great Plains. We examined the effects of leafy spurge infestation on densities of breeding birds, nest-site selection, and nest success in grasslands on the Sheyenne National Grassland (SNG), North Dakota, USA, 1999-2000. We categorized spurge-infested grasslands into 3 groups (low, medium, high), based on the area covered by spurge patches. We surveyed 75 100-m-radius circular points (25 in each group), and searched for nests in 6 16-ha plots (2 in each group). Grasshopper sparrow (Ammodramus savannarum) and savannah sparrow (Passerculus sandwichensis) densities were lower on high-spurge points than on low- and medium-spurge points. Bobolink (Dolichonyx oryzivorus) and western meadowlark (Sturnella neglecta) densities were not significantly different among spurge cover groups. Spurge cover did not appear to be an important factor in nest-site selection. However, western meadowlark nest success was positively associated with spurge cover. Vegetation structure is an important indicator of habitat quality and resource availability for grassland birds. Changes in vegetation structure caused by introduced plant species, such as spurge, can alter resource availability and hence affect bird community composition. Managers of spurge-infested grasslands should continue current spurge control measures to help prevent further declines in grassland habitat quality and grassland bird populations.

Conservation of forest birds: evidence of a shifting baseline in community structure.

PubMed

Rittenhouse, Chadwick D; Pidgeon, Anna M; Albright, Thomas P; Culbert, Patrick D; Clayton, Murray K; Flather, Curtis H; Huang, Chengquan; Masek, Jeffrey G; Stewart, Susan I; Radeloff, Volker C

2010-08-02

Quantifying changes in forest bird diversity is an essential task for developing effective conservation actions. When subtle changes in diversity accumulate over time, annual comparisons may offer an incomplete perspective of changes in diversity. In this case, progressive change, the comparison of changes in diversity from a baseline condition, may offer greater insight because changes in diversity are assessed over longer periods of times. Our objectives were to determine how forest bird diversity has changed over time and whether those changes were associated with forest disturbance. We used North American Breeding Bird Survey data, a time series of Landsat images classified with respect to land cover change, and mixed-effects models to associate changes in forest bird community structure with forest disturbance, latitude, and longitude in the conterminous United States for the years 1985 to 2006. We document a significant divergence from the baseline structure for all birds of similar migratory habit and nest location, and all forest birds as a group from 1985 to 2006. Unexpectedly, decreases in progressive similarity resulted from small changes in richness (<1 species per route for the 22-year study period) and modest losses in abundance (-28.7 - -10.2 individuals per route) that varied by migratory habit and nest location. Forest disturbance increased progressive similarity for Neotropical migrants, permanent residents, ground nesting, and cavity nesting species. We also documented highest progressive similarity in the eastern United States. Contemporary forest bird community structure is changing rapidly over a relatively short period of time (e.g., approximately 22 years). Forest disturbance and forest regeneration are primary factors associated with contemporary forest bird community structure, longitude and latitude are secondary factors, and forest loss is a tertiary factor. Importantly, these findings suggest some regions of the United States may already fall below the habitat amount threshold where fragmentation effects become important predictors of forest bird community structure.

Monoculture of Leafcutter Ant Gardens

PubMed Central

Mueller, Ulrich G.; Scott, Jarrod J.; Ishak, Heather D.; Cooper, Michael; Rodrigues, Andre

2010-01-01

Background Leafcutter ants depend on the cultivation of symbiotic Attamyces fungi for food, which are thought to be grown by the ants in single-strain, clonal monoculture throughout the hundreds to thousands of gardens within a leafcutter nest. Monoculture eliminates cultivar-cultivar competition that would select for competitive fungal traits that are detrimental to the ants, whereas polyculture of several fungi could increase nutritional diversity and disease resistance of genetically variable gardens. Methodology/Principal Findings Using three experimental approaches, we assessed cultivar diversity within nests of Atta leafcutter ants, which are most likely among all fungus-growing ants to cultivate distinct cultivar genotypes per nest because of the nests' enormous sizes (up to 5000 gardens) and extended lifespans (10–20 years). In Atta texana and in A. cephalotes, we resampled nests over a 5-year period to test for persistence of resident cultivar genotypes within each nest, and we tested for genetic differences between fungi from different nest sectors accessed through excavation. In A. texana, we also determined the number of Attamyces cells carried as a starter inoculum by a dispersing queens (minimally several thousand Attamyces cells), and we tested for genetic differences between Attamyces carried by sister queens dispersing from the same nest. Except for mutational variation arising during clonal Attamyces propagation, DNA fingerprinting revealed no evidence for fungal polyculture and no genotype turnover during the 5-year surveys. Conclusions/Significance Atta leafcutter ants can achieve stable, fungal monoculture over many years. Mutational variation emerging within an Attamyces monoculture could provide genetic diversity for symbiont choice (gardening biases of the ants favoring specific mutational variants), an analog of artificial selection. PMID:20844760

Environmental correlates of breeding in the Crested Caracara (Caracara cheriway)

USGS Publications Warehouse

Morrison, J.L.; Pias, Kyle E.; Cohen, J.B.; Catlin, D.H.

2009-01-01

We evaluated the influence of weather on reproduction of the Crested Caracara (Caracara cheriway) in an agricultural landscape in south-central Florida. We used a mixed logistic-regression modeling approach within an information-theoretic framework to examine the influence of total rainfall, rainfall frequency, and temperature on the number of breeding pairs, timing of breeding, nest success, and productivity of Crested Caracaras during 1994–2000. The best models indicated an influence of rainfall frequency and laying period on reproduction. More individuals nested and more pairs nested earlier during years with more frequent rainfall in late summer and early fall. Pairs that nested later in each breeding season had smaller clutches, lower nest success and productivity, and higher probability of nest failure. More frequent rainfall during early spring months that are usually characterized by water deficit (March–May), more frequent rainfall during the fall drawdown period (September–November), and a shorter winter dry period showed some association with higher probability of brood reduction and lower nest success. The proportion of nests that failed was higher in “wet” years, when total rainfall during the breeding season (September–April) was >10% above the 20-year average. Rainfall may influence reproduction in Crested Caracaras indirectly through food resources. As total rainfall increased during February–April, when most pairs are feeding nestlings or dependent fledglings, the proportion of drawdown-dependent species (those that become available as rainfall decreases and wetlands become isolated and shallow) in the diet of Crested Caracaras declined, which may indicate reduced availability of foraging habitat for this primarily terrestrial raptor.

Reproductive behavior of the great hornbill (Buceros bicornis).

PubMed

Kozlowski, Corinne P; Bauman, Karen L; Asa, Cheryl S

2015-01-01

Great hornbills (Buceros bicornis) are a long-lived, monogamous species that forms strong pair-bonds, and mate compatibility is thought to be important for successful reproduction. Within AZA, great hornbills are listed as a red SSP. The population consists of a limited number of individuals that do not breed reliably, and improving reproduction is a top priority for the Coraciiformes TAG. To better understand mating behavior and evaluate mate compatibility, this study documented the behavior of pairs of great hornbills during and immediately after courtship. Using live observations, the study followed one female, an experienced and successful breeder, as she was paired with four successive males over 11 breeding seasons. Initially, males frequently vocalized, investigated the nest, and approached the female. As the female spent more time in the nest, these behaviors were replaced by regurgitation and food offering. The female was most often observed plastering and vocalizing. Behavioral differences between successful and unsuccessful pairs, possibly indicative of pair compatibility, included rates of approaching, billing, and biting. Numerous behaviors occurred more frequently during years that a chick hatched, including pseudoregurgitation, regurgitation, offering food items, and nest investigation. Males also spent more time in proximity to both the female and the nest during years that a chick hatched. Together, these results suggest that the amount of time pairs spend in proximity, the amount of time a male spends near the nest, and the frequency of certain behaviors may help evaluate compatibility and the likelihood of successful reproduction for pairs of great hornbills. © 2015 Wiley Periodicals, Inc.

Creating raptor benefits from powerline problems

USGS Publications Warehouse

Kochert, Michael N.; Olendorff, R.R.

1999-01-01

Powerlines benefit raptors by providing enhanced nesting and roosting sites. However, they also can kill raptors by electrocution and raptors can interfere with power transmission. The electrocution problem has been reduced by correcting existing lethal lines and implementing electrocution safe designs for new lines. Remedial actions include pole modifications, perch management and insulation of wires and hardware. New line designs provide for proper insulation and adequate spacing of conductors and grounded hardware. Nesting platforms can reduce power transmission problems and enhance the benefits of nesting on powerlines. A combination of perch deterrents and insulator shields is a positive, cost-effective approach to managing bird contamination that allows birds to continue roosting on the towers.

Spatial structure and nest demography reveal the influence of competition, parasitism and habitat quality on slavemaking ants and their hosts

PubMed Central

2011-01-01

Background Natural communities are structured by intra-guild competition, predation or parasitism and the abiotic environment. We studied the relative importance of these factors in two host-social parasite ecosystems in three ant communities in Europe (Bavaria) and North America (New York, West Virginia). We tested how these factors affect colony demography, life-history and the spatial pattern of colonies, using a large sample size of more than 1000 colonies. The strength of competition was measured by the distance to the nearest competitor. Distance to the closest social parasite colony was used as a measure of parasitism risk. Nest sites (i.e., sticks or acorns) are limited in these forest ecosystems and we therefore included nest site quality as an abiotic factor in the analysis. In contrast to previous studies based on local densities, we focus here on the positioning and spatial patterns and we use models to compare our predictions to random expectations. Results Colony demography was universally affected by the size of the nest site with larger and more productive colonies residing in larger nest sites of higher quality. Distance to the nearest competitor negatively influenced host demography and brood production in the Bavarian community, pointing to an important role of competition, while social parasitism was less influential in this community. The New York community was characterized by the highest habitat variability, and productive colonies were clustered in sites of higher quality. Colonies were clumped on finer spatial scales, when we considered only the nearest neighbors, but more regularly distributed on coarser scales. The analysis of spatial positioning within plots often produced different results compared to those based on colony densities. For example, while host and slavemaker densities are often positively correlated, slavemakers do not nest closer to potential host colonies than expected by random. Conclusions The three communities are differently affected by biotic and abiotic factors. Some of the differences can be attributed to habitat differences and some to differences between the two slavemaking-host ecosystems. The strong effect of competition in the Bavarian community points to the scarcity of resources in this uniform habitat compared to the other more diverse sites. The decrease in colony aggregation with scale indicates fine-scale resource hotspots: colonies are locally aggregated in small groups. Our study demonstrates that species relationships vary across scales and spatial patterns can provide important insights into species interactions. These results could not have been obtained with analyses based on local densities alone. Previous studies focused on social parasitism and its effect on host colonies. The broader approach taken here, considering several possible factors affecting colony demography and not testing each one in isolation, shows that competition and environmental variability can have a similar strong impact on demography and life-history of hosts. We conclude that the effects of parasites or predators should be studied in parallel to other ecological influences. PMID:21443778

Spatial structure and nest demography reveal the influence of competition, parasitism and habitat quality on slavemaking ants and their hosts.

PubMed

Scharf, Inon; Fischer-Blass, Birgit; Foitzik, Susanne

2011-03-28

Natural communities are structured by intra-guild competition, predation or parasitism and the abiotic environment. We studied the relative importance of these factors in two host-social parasite ecosystems in three ant communities in Europe (Bavaria) and North America (New York, West Virginia). We tested how these factors affect colony demography, life-history and the spatial pattern of colonies, using a large sample size of more than 1000 colonies. The strength of competition was measured by the distance to the nearest competitor. Distance to the closest social parasite colony was used as a measure of parasitism risk. Nest sites (i.e., sticks or acorns) are limited in these forest ecosystems and we therefore included nest site quality as an abiotic factor in the analysis. In contrast to previous studies based on local densities, we focus here on the positioning and spatial patterns and we use models to compare our predictions to random expectations. Colony demography was universally affected by the size of the nest site with larger and more productive colonies residing in larger nest sites of higher quality. Distance to the nearest competitor negatively influenced host demography and brood production in the Bavarian community, pointing to an important role of competition, while social parasitism was less influential in this community. The New York community was characterized by the highest habitat variability, and productive colonies were clustered in sites of higher quality. Colonies were clumped on finer spatial scales, when we considered only the nearest neighbors, but more regularly distributed on coarser scales. The analysis of spatial positioning within plots often produced different results compared to those based on colony densities. For example, while host and slavemaker densities are often positively correlated, slavemakers do not nest closer to potential host colonies than expected by random. The three communities are differently affected by biotic and abiotic factors. Some of the differences can be attributed to habitat differences and some to differences between the two slavemaking-host ecosystems. The strong effect of competition in the Bavarian community points to the scarcity of resources in this uniform habitat compared to the other more diverse sites. The decrease in colony aggregation with scale indicates fine-scale resource hotspots: colonies are locally aggregated in small groups. Our study demonstrates that species relationships vary across scales and spatial patterns can provide important insights into species interactions. These results could not have been obtained with analyses based on local densities alone. Previous studies focused on social parasitism and its effect on host colonies. The broader approach taken here, considering several possible factors affecting colony demography and not testing each one in isolation, shows that competition and environmental variability can have a similar strong impact on demography and life-history of hosts. We conclude that the effects of parasites or predators should be studied in parallel to other ecological influences.

Statistical and procedural issues in the use of heated taxidermic mounts

USGS Publications Warehouse

Bakken, G.S.; Kenow, K.P.; Korschgen, C.E.; Boysen, A.F.

2000-01-01

Studies using mounts have an inherently nested error structure; calibration and standardization should use the appropriate procedures and statistics. One example is that individual mount differences are nested within morphological factors related to species, age, or gender; without replication, mount differences may be confused with differences due to morphology. Also, the sensitivity of mounts to orientation to wind or sun is nested within mount; without replication, inadvertent variation in mount positioning may be confused with differences among mounts. Data on heat loss from a of 1-day-old mallard duckling mount are used to illustrate orientation sensitivity. (C) 2000 Elsevier Science Ltd. All rights reserved.

Essays on pricing dynamics, price dispersion, and nested logit modelling

NASA Astrophysics Data System (ADS)

Verlinda, Jeremy Alan

The body of this dissertation comprises three standalone essays, presented in three respective chapters. Chapter One explores the possibility that local market power contributes to the asymmetric relationship observed between wholesale costs and retail prices in gasoline markets. I exploit an original data set of weekly gas station prices in Southern California from September 2002 to May 2003, and take advantage of highly detailed station and local market-level characteristics to determine the extent to which spatial differentiation influences price-response asymmetry. I find that brand identity, proximity to rival stations, bundling and advertising, operation type, and local market features and demographics each influence a station's predicted asymmetric relationship between prices and wholesale costs. Chapter Two extends the existing literature on the effect of market structure on price dispersion in airline fares by modeling the effect at the disaggregate ticket level. Whereas past studies rely on aggregate measures of price dispersion such as the Gini coefficient or the standard deviation of fares, this paper estimates the entire empirical distribution of airline fares and documents how the shape of the distribution is determined by market structure. Specifically, I find that monopoly markets favor a wider distribution of fares with more mass in the tails while duopoly and competitive markets exhibit a tighter fare distribution. These findings indicate that the dispersion of airline fares may result from the efforts of airlines to practice second-degree price discrimination. Chapter Three adopts a Bayesian approach to the problem of tree structure specification in nested logit modelling, which requires a heavy computational burden in calculating marginal likelihoods. I compare two different techniques for estimating marginal likelihoods: (1) the Laplace approximation, and (2) reversible jump MCMC. I apply the techniques to both a simulated and a travel mode choice data set, and find that model selection is invariant to prior specification, while model derivatives like willingness-to-pay are notably sensitive to model choice. I also find that the Laplace approximation is remarkably accurate in spite of the potential for nested logit models to have irregular likelihood surfaces.

Structure of northern spotted owl nest stands and their historical conditions on the eastern slope of the Pacific Northwest Cascades, USA.

Treesearch

Richard Everett; D. Schellhaas; D. Spurbeck; [and others].

1997-01-01

The northern spotted (Strix occidentalis caurina) uses a wide array of nesting habitat throughout its current range and successfully reproduces in a variety of stand types on the eastern slope of the Pacific Northwest Cascades. The species has the ability to utilize dynamic forest stands that continue to undergo significant changes in tree density...

Estimating occupancy dynamics for large-scale monitoring networks: amphibian breeding occupancy across protected areas in the northeast United States

USGS Publications Warehouse

Miller, David A.W.; Grant, Evan H. Campbell

2015-01-01

Regional monitoring strategies frequently employ a nested sampling design where a finite set of study areas from throughout a region are selected within which intensive sub-sampling occurs. This sampling protocol naturally lends itself to a hierarchical analysis to account for dependence among sub-samples. Implementing such an analysis within a classic likelihood framework is computationally prohibitive with species occurrence data when accounting for detection probabilities. Bayesian methods offer an alternative framework to make this analysis feasible. We demonstrate a general approach for estimating occupancy when data come from a nested sampling design. Using data from a regional monitoring program of wood frogs (Lithobates sylvaticus) and spotted salamanders (Ambystoma maculatum) in vernal pools, we analyzed data using static and dynamic occupancy frameworks. We analyzed observations from 2004-2013collected within 14 protected areas located throughout the northeast United States . We use the data set to estimate trends in occupancy at both the regional and individual protected area level. We show that occupancy at the regional level was relatively stable for both species. Much more variation occurred within individual study areas, with some populations declining and some increasing for both species. We found some evidence for a latitudinal gradient in trends among protected areas. However, support for this pattern is overestimated when the hierarchical nature of the data collection is not controlled for in the analysis. For both species, occupancy appeared to be declining in the most southern areas, while occupancy was stable or increasing in more northern areas. These results shed light on the range-level population status of these pond-breeding amphibians and our approach provides a framework that can be used to examine drivers of change including among-year and among-site variation in occurrence dynamics, while properly accounting for nested structure of data collection.

Hierarchical population monitoring of greater sage-grouse (Centrocercus urophasianus) in Nevada and California—Identifying populations for management at the appropriate spatial scale

USGS Publications Warehouse

Coates, Peter S.; Prochazka, Brian G.; Ricca, Mark A.; Wann, Gregory T.; Aldridge, Cameron L.; Hanser, Steven E.; Doherty, Kevin E.; O'Donnell, Michael S.; Edmunds, David R.; Espinosa, Shawn P.

2017-08-10

Population ecologists have long recognized the importance of ecological scale in understanding processes that guide observed demographic patterns for wildlife species. However, directly incorporating spatial and temporal scale into monitoring strategies that detect whether trajectories are driven by local or regional factors is challenging and rarely implemented. Identifying the appropriate scale is critical to the development of management actions that can attenuate or reverse population declines. We describe a novel example of a monitoring framework for estimating annual rates of population change for greater sage-grouse (Centrocercus urophasianus) within a hierarchical and spatially nested structure. Specifically, we conducted Bayesian analyses on a 17-year dataset (2000–2016) of lek counts in Nevada and northeastern California to estimate annual rates of population change, and compared trends across nested spatial scales. We identified leks and larger scale populations in immediate need of management, based on the occurrence of two criteria: (1) crossing of a destabilizing threshold designed to identify significant rates of population decline at a particular nested scale; and (2) crossing of decoupling thresholds designed to identify rates of population decline at smaller scales that decouple from rates of population change at a larger spatial scale. This approach establishes how declines affected by local disturbances can be separated from those operating at larger scales (for example, broad-scale wildfire and region-wide drought). Given the threshold output from our analysis, this adaptive management framework can be implemented readily and annually to facilitate responsive and effective actions for sage-grouse populations in the Great Basin. The rules of the framework can also be modified to identify populations responding positively to management action or demonstrating strong resilience to disturbance. Similar hierarchical approaches might be beneficial for other species occupying landscapes with heterogeneous disturbance and climatic regimes.

Mixed-stock analysis reveals the migrations of juvenile hawksbill turtles (Eretmochelys imbricata) in the Caribbean Sea.

PubMed

Bowen, B W; Grant, W S; Hillis-Starr, Z; Shaver, D J; Bjorndal, K A; Bolten, A B; Bass, A L

2007-01-01

Hawksbill turtles (Eretmochelys imbricata) migrate between nesting beaches and feeding habitats that are often associated with tropical reefs, but it is uncertain which nesting colonies supply which feeding habitats. To address this gap in hawksbill biology, we compile previously published and new mitochondrial DNA (mtDNA) haplotype data for 10 nesting colonies (N = 347) in the western Atlantic and compare these profiles to four feeding populations and four previously published feeding samples (N = 626). Nesting colonies differ significantly in mtDNA haplotype frequencies (Phi(ST) = 0.588, P < 0.001), corroborating earlier conclusions of nesting site fidelity and setting the stage for mixed-stock analysis. Feeding aggregations show lower but significant structure (Phi(ST) = 0.089, P < 0.001), indicating that foraging populations are not homogenous across the Caribbean Sea. Bayesian mixed-stock estimates of the origins of juveniles in foraging areas show a highly significant, but shallow, correlation with nesting population size (r = 0.378, P = 0.004), supporting the premise that larger rookeries contribute more juveniles to feeding areas. A significant correlation between the estimated contribution and geographical distance from nesting areas (r = -0.394, P = 0.003) demonstrates the influence of proximity on recruitment to feeding areas. The influence of oceanic currents is illustrated by pelagic stage juveniles stranded in Texas, which are assigned primarily (93%) to the upstream rookery in Yucatan. One juvenile had a haplotype previously identified only in the eastern Atlantic, invoking rare trans-oceanic migrations. The mixed-stock analysis demonstrates that harvests in feeding habitats will impact nesting colonies throughout the region, with the greatest detriment to nearby nesting populations.

Determining origin in a migratory marine vertebrate: a novel method to integrate stable isotopes and satellite tracking

USGS Publications Warehouse

Vander Zanden, Hannah B.; Tucker, Anton D.; Hart, Kristen M.; Lamont, Margaret M.; Fujisaki, Ikuko; Addison, David S.; Mansfield, Katherine L.; Phillips, Katrina F.; Wunder, Michael B.; Bowen, Gabriel J.; Pajuelo, Mariela; Bolten, Alan B.; Bjorndal, Karen A.

2015-01-01

Stable isotope analysis is a useful tool to track animal movements in both terrestrial and marine environments. These intrinsic markers are assimilated through the diet and may exhibit spatial gradients as a result of biogeochemical processes at the base of the food web. In the marine environment, maps to predict the spatial distribution of stable isotopes are limited, and thus determining geographic origin has been reliant upon integrating satellite telemetry and stable isotope data. Migratory sea turtles regularly move between foraging and reproductive areas. Whereas most nesting populations can be easily accessed and regularly monitored, little is known about the demographic trends in foraging populations. The purpose of the present study was to examine migration patterns of loggerhead nesting aggregations in the Gulf of Mexico (GoM), where sea turtles have been historically understudied. Two methods of geographic assignment using stable isotope values in known-origin samples from satellite telemetry were compared: 1) a nominal approach through discriminant analysis and 2) a novel continuous-surface approach using bivariate carbon and nitrogen isoscapes (isotopic landscapes) developed for this study. Tissue samples for stable isotope analysis were obtained from 60 satellite-tracked individuals at five nesting beaches within the GoM. Both methodological approaches for assignment resulted in high accuracy of foraging area determination, though each has advantages and disadvantages. The nominal approach is more appropriate when defined boundaries are necessary, but up to 42% of the individuals could not be considered in this approach. All individuals can be included in the continuous-surface approach, and individual results can be aggregated to identify geographic hotspots of foraging area use, though the accuracy rate was lower than nominal assignment. The methodological validation provides a foundation for future sea turtle studies in the region to inexpensively determine geographic origin for large numbers of untracked individuals. Regular monitoring of sea turtle nesting aggregations with stable isotope sampling can be used to fill critical data gaps regarding habitat use and migration patterns. Probabilistic assignment to origin with isoscapes has not been previously used in the marine environment, but the methods presented here could also be applied to other migratory marine species.

Determining origin in a migratory marine vertebrate: a novel method to integrate stable isotopes and satellite tracking.

PubMed

Zanden, Hannah B Vander; Tucker, Anton D; Hart, Kristen M; Lamont, Margaret M; Fuisaki, Ikuko; Addison, David; Mansfield, Katherine L; Phillips, Katrina F; Wunder, Michael B; Bowen, Gabriel J; Pajuelo, Mariela; Bolten, Alan B; Bjorndal, Karen A

2015-03-01

Stable isotope analysis is a useful tool to track animal movements in both terrestrial and marine environments. These intrinsic markers are assimilated through the diet and may exhibit spatial gradients as a result of biogeochemical processes at the base of the food web. In the marine environment, maps to predict the spatial distribution of stable isotopes are limited, and thus determining geographic origin has been reliant upon integrating satellite telemetry and stable isotope data. Migratory sea turtles regularly move between foraging and reproductive areas. Whereas most nesting populations can be easily accessed and regularly monitored, little is known about the demographic trends in foraging populations. The purpose of the present study was to examine migration patterns of loggerhead nesting aggregations in the Gulf of Mexico (GoM), where sea turtles have been historically understudied. Two methods of geographic assignment using stable isotope values in known-origin samples from satellite telemetry were compared: (1) a nominal approach through discriminant analysis and (2) a novel continuous-surface approach using bivariate carbon and nitrogen isoscapes (isotopic landscapes) developed for this study. Tissue samples for stable isotope analysis were obtained from 60 satellite-tracked individuals at five nesting beaches within the GoM. Both methodological approaches for assignment resulted in high accuracy of foraging area determination, though each has advantages and disadvantages. The nominal approach is more appropriate when defined boundaries are necessary, but up to 42% of the individuals could not be considered in this approach. All individuals can be included in the continuous-surface approach, and individual results can be aggregated to identify geographic hotspots of foraging area use, though the accuracy rate was lower than nominal assignment. The methodological validation provides a foundation for future sea turtle studies in the region to inexpensively determine geographic origin for large numbers of untracked individuals. Regular monitoring of sea turtle nesting aggregations with stable isotope sampling can be used to fill critical data gaps regarding habitat use and migration patterns. Probabilistic assignment to origin with isoscapes has not been previously used in the marine environment, but the methods presented here could also be applied to other migratory marine species.

The differential emission measure of nested hot and cool magnetic loops

NASA Technical Reports Server (NTRS)

Van Hoven, G.; Mok, Y.

1993-01-01

The detailed thermal structure of the magnetized solar transition region, as measured by its differential emission measure (DEM(T)), is poorly known. Building on the fact that the solar surface is strongly magnetized and thereby structured, proposals have been made that envision a significant lower-temperature contribution to the energy balance from (ion) heat flux across an arcade of different temperature loops. In this paper, we describe a self-consistent 2D MHD simulation, which includes the full thermal effects of parallel stability and anisotropic conduction, of a nested-loop model of the thermal and magnetic structure of the transition region. We then demonstrate that the predicted DEM agrees with observations in the conceptually elusive T less than 10 exp 5 K regime.

Managing native predators: Evidence from a partial removal of raccoons (Procyon lotor) on the Outer Banks of North Carolina, USA

USGS Publications Warehouse

Stocking, Jessica J.; Simons, Theodore R.; Parsons, Arielle W.; O'Connell, Allan F.

2017-01-01

Raccoons (Procyon lotor) are important predators of ground-nesting species in coastal systems. They have been identified as a primary cause of nest failure for the American Oystercatcher (Haematopus palliatus) throughout its range. Concerns over the long-term effects of raccoon predation and increased nest success following a hurricane inspired a mark-resight study of the raccoon population on a barrier island off North Carolina, USA. Approximately half of the raccoons were experimentally removed in 2008. Nests (n = 700) were monitored on two adjacent barrier islands during 2004–2013. Daily nest survival estimates were highest for 2004 (0.974 ± 0.005) and lowest for 2007 and 2008 (0.925 ± 0.009 and 0.925 ± 0.010, respectively). The only model in our candidate set that received any support included island and time of season, along with a diminishing effect of the hurricane and a constant, 5-year effect of the raccoon removal. For both hurricane and raccoon removal, however, the support for island-specific effects was weak (β = -0.204 ± 0.116 and 0.146 ± 0.349, respectively). We conclude that either the raccoon reduction was inadequate, or factors other than predation cause more variation in nest success than previously recognized. A multi-faceted approach to management aimed at reducing nest losses to storm overwash, predation, and human disturbance is likely to yield the largest population level benefits.

First-order system least squares and the energetic variational approach for two-phase flow

NASA Astrophysics Data System (ADS)

Adler, J. H.; Brannick, J.; Liu, C.; Manteuffel, T.; Zikatanov, L.

2011-07-01

This paper develops a first-order system least-squares (FOSLS) formulation for equations of two-phase flow. The main goal is to show that this discretization, along with numerical techniques such as nested iteration, algebraic multigrid, and adaptive local refinement, can be used to solve these types of complex fluid flow problems. In addition, from an energetic variational approach, it can be shown that an important quantity to preserve in a given simulation is the energy law. We discuss the energy law and inherent structure for two-phase flow using the Allen-Cahn interface model and indicate how it is related to other complex fluid models, such as magnetohydrodynamics. Finally, we show that, using the FOSLS framework, one can still satisfy the appropriate energy law globally while using well-known numerical techniques.

Compilation of 1990 annual reports of the Navy ELF communications system ecological monitoring program. Volume 2: Tabs C thru F

NASA Astrophysics Data System (ADS)

Zapotosky, J. E.

1991-08-01

This portion of the report includes monitoring of and data for arthropoda and earthworms; pollinating insects; and small mammals and nesting birds. During the 1990 growing season the ELF antenna was operated more frequently than in prior years. This provides 2 years of intermittent ELF exposure for the biological systems to react to the radiation, one year of very limited exposure and greater exposure in 1990. Arthropod and earthworm sampling was conducted at intervals of two weeks from early May to late October. High voltage transmission lines and magnetic fields have been shown to affect honeybee reproduction, survival, orientation, and nest structure. ELF EM fields could have similar effects on native megachild bees. Changes in cell length, number of cells per nest, number of leaver per cell, orientation of nest entrances, and time to collect a round leaf pierce to cap a cell were monitored. We have not detected significant changes that could be attributed to ELF EM fields. Small mammal and nesting bird biological studies in the western Upper Peninsula of Michigan for the year 1990 are reported.

The evolution of eggshell cuticle in relation to nesting ecology

PubMed Central

Hauber, Mark E.

2016-01-01

Avian eggs are at risk of microbial infection prior to and during incubation. A large number of defence mechanisms have evolved in response to the severe costs imposed by these infections. The eggshell's cuticle is an important component of antimicrobial defence, and its role in preventing contamination by microorganisms in domestic chickens is well known. Nanometer-scale cuticular spheres that reduce microbial attachment and penetration have recently been identified on eggs of several wild avian species. However, whether these spheres have evolved specifically for antimicrobial defence is unknown. Here, we use comparative data on eggshell cuticular structure and nesting ecology to test the hypothesis that birds nesting in habitats with higher risk of infection (e.g. wetter and warmer) are more likely to evolve cuticular nanospheres on their eggshells than those nesting in less risky habitats. We found that nanostructuring, present in 54 of 296 analysed species, is the ancestral condition of avian eggshells and has been retained more often in taxa that nest in humid infection-prone environments, suggesting that they serve critical roles in antimicrobial egg defence. PMID:27488648

The evolution of eggshell cuticle in relation to nesting ecology.

PubMed

D'Alba, Liliana; Maia, Rafael; Hauber, Mark E; Shawkey, Matthew D

2016-08-17

Avian eggs are at risk of microbial infection prior to and during incubation. A large number of defence mechanisms have evolved in response to the severe costs imposed by these infections. The eggshell's cuticle is an important component of antimicrobial defence, and its role in preventing contamination by microorganisms in domestic chickens is well known. Nanometer-scale cuticular spheres that reduce microbial attachment and penetration have recently been identified on eggs of several wild avian species. However, whether these spheres have evolved specifically for antimicrobial defence is unknown. Here, we use comparative data on eggshell cuticular structure and nesting ecology to test the hypothesis that birds nesting in habitats with higher risk of infection (e.g. wetter and warmer) are more likely to evolve cuticular nanospheres on their eggshells than those nesting in less risky habitats. We found that nanostructuring, present in 54 of 296 analysed species, is the ancestral condition of avian eggshells and has been retained more often in taxa that nest in humid infection-prone environments, suggesting that they serve critical roles in antimicrobial egg defence. © 2016 The Author(s).

Cloud Intrusion Detection and Repair (CIDAR)

DTIC Science & Technology

2016-02-01

form for VLC , Swftools-png2swf, Swftools-jpeg2swf, Dillo and GIMP. The superscript indicates the bit width of each expression atom. “sext(v, w... challenges in input rectification is the need to deal with nested fields. In general, input formats are in tree structures containing arbitrarily...length indicator constraints is challeng - ing, because of the presence of nested fields in hierarchical input format. For example, an integer field may

An efficiency study of the simultaneous analysis and design of structures

NASA Technical Reports Server (NTRS)

Striz, Alfred G.; Wu, Zhiqi; Sobieski, Jaroslaw

1995-01-01

The efficiency of the Simultaneous Analysis and Design (SAND) approach in the minimum weight optimization of structural systems subject to strength and displacement constraints as well as size side constraints is investigated. SAND allows for an optimization to take place in one single operation as opposed to the more traditional and sequential Nested Analysis and Design (NAND) method, where analyses and optimizations alternate. Thus, SAND has the advantage that the stiffness matrix is never factored during the optimization retaining its original sparsity. One of SAND's disadvantages is the increase in the number of design variables and in the associated number of constraint gradient evaluations. If SAND is to be an acceptable player in the optimization field, it is essential to investigate the efficiency of the method and to present a possible cure for any inherent deficiencies.

Temporal changes in the structure of a plant-frugivore network are influenced by bird migration and fruit availability

PubMed Central

Andresen, Ellen; Díaz-Castelazo, Cecilia

2016-01-01

Background. Ecological communities are dynamic collections whose composition and structure change over time, making up complex interspecific interaction networks. Mutualistic plant–animal networks can be approached through complex network analysis; these networks are characterized by a nested structure consisting of a core of generalist species, which endows the network with stability and robustness against disturbance. Those mutualistic network structures can vary as a consequence of seasonal fluctuations and food availability, as well as the arrival of new species into the system that might disorder the mutualistic network structure (e.g., a decrease in nested pattern). However, there is no assessment on how the arrival of migratory species into seasonal tropical systems can modify such patterns. Emergent and fine structural temporal patterns are adressed here for the first time for plant-frugivorous bird networks in a highly seasonal tropical environment. Methods. In a plant-frugivorous bird community, we analyzed the temporal turnover of bird species comprising the network core and periphery of ten temporal interaction networks resulting from different bird migration periods. Additionally, we evaluated how fruit abundance and richness, as well as the arrival of migratory birds into the system, explained the temporal changes in network parameters such as network size, connectance, nestedness, specialization, interaction strength asymmetry and niche overlap. The analysis included data from 10 quantitative plant-frugivorous bird networks registered from November 2013 to November 2014. Results. We registered a total of 319 interactions between 42 plant species and 44 frugivorous bird species; only ten bird species were part of the network core. We witnessed a noteworthy turnover of the species comprising the network periphery during migration periods, as opposed to the network core, which did not show significant temporal changes in species composition. Our results revealed that migration and fruit richness explain the temporal variations in network size, connectance, nestedness and interaction strength asymmetry. On the other hand, fruit abundance only explained connectance and nestedness. Discussion. By means of a fine-resolution temporal analysis, we evidenced for the first time how temporal changes in the interaction network structure respond to the arrival of migratory species into the system and to fruit availability. Additionally, few migratory bird species are important links for structuring networks, while most of them were peripheral species. We showed the relevance of studying bird–plant interactions at fine temporal scales, considering changing scenarios of species composition with a quantitative network approach. PMID:27330852

Communities of Social Bees (Apidae: Meliponini) in Trap-Nests: the Spatial Dynamics of Reproduction in an Area of Atlantic Forest.

PubMed

Silva, M D; Ramalho, M; Monteiro, D

2014-08-01

As most stingless bee species depend on preexisting cavities, principally tree hollows, nesting site availability may represent an important restriction in the structuring of their forest communities. The present study examined the spatial dynamics of stingless bee communities in an area of Atlantic Forest by evaluating their swarming to trap-nests. The field work was performed in the Michelin Ecological Reserve (MER) on the southeastern coast of the state of Bahia, Brazil. Seven hundred and twenty trap-nests were distributed within two forest habitats in advanced and initial stages of regeneration. The trap-nests were monitored between September 2009 and March 2011. Twenty-five trap-nests were occupied by five bee species, resulting in a capture ratio of 0.035 swarms/trap (approximately 0.14 swarms/ha), corresponding to 10 swarms/year (0.056 swarms/ha/year). According to previous study at MER, the most abundant species in natural nests were also the most common in trap-nests in the two forest habitats examined, with the exception of Melipona scutellaris Latreille. Swarms of higher numbers of species were captured in initial regeneration stage forests than in advanced regeneration stage areas, and differences in species compositions were significant between both habitats (p = 0.03); these apparent differences were not consistent, however, when considering richness (p = 0.14) and total abundance (p = 0.08). The present study suggests the existence of a minimum cavity size threshold of approximately 1 L for most local species of stingless bees and sustains the hypothesis of a mass effect of Tetragonisca angustula Latreille populations from surrounding disturbed habitats on the MER forest community in terms of propagule (swarm) pressure. Examining swarm densities with trap-nests can be a promising technique for comparative analyses of the carrying capacities of forest habitats for stingless bee colonies, as long as size thresholds of cavities for nesting are taken into consideration.

Impacts of Water Levels on Breeding Canada Geese and Methods for Mitigation and Management in the Southern Flathead Valley, Montana, 1983-1987 Final Report.

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

Mackey, Dennis L.; Gregory, Shari K.; Matthews, William C. Jr.

Kerr Hydroelectric Dam is located at the south end of Flathead Lake, controls water levels on the lake and the Flathead River below the dam, and is currently operated as a load control facility. Current operation of Kerr Dam creates the greatest yearly water level fluctuations on both the lake and river during the Canada goose (Branta canadensis moffitti) brood and nesting period. Data collected from 1980-1982 indicated that goose nest numbers on the river were lower than during the 1950's, and that brood habitat on the lake may be limiting the goose population there. Our study was conducted frommore » 1983-1987 to determine the effects of Kerr Dam operation on Canada goose populations and habitat on the south half of Flathead Lake and the Flathead River, and to formulate management and mitigation recommendations. Nesting geese on the river appeared to be negatively affected by a lack of nest sites free from predators, and responded to available artificial nest structures with an increase in nest numbers and nesting success. Under current dam operation, river channel depths and widths do not discourage access to nesting islands by mammalian predators during some years and high predation on ground nests occurs. Intensively used brood areas on the lake and river were identified and described. Brood habitat on the lake was lower in quality and quantity than on the river due to dam operations. Gosling mortality on the lake was high, almost 2 times higher than on the river. Lake broods expended more energy obtaining food than river broods. Losses of brood habitat in the form of wet meadow marshes were documented and mitigation options developed. Management/mitigation alternatives and monitoring methods for nesting and brooding geese were identified.« less

Interphyletic relationships in the use of nesting cavities: mutualism, competition and amensalism among hymenopterans and vertebrates

NASA Astrophysics Data System (ADS)

Veiga, José P.; Wamiti, Wanyoike; Polo, Vicente; Muchai, Muchane

2013-09-01

Although competition is usually assumed to be the most common interaction between closely related organisms that share limiting resources, the relationships linking distant taxa that use the same nesting sites are poorly understood. In the present study, we examine the interactions among social hymenopterans (honeybees and wasps) and vertebrates in tropical ecosystems of East Africa. By analysing the preferences of these three groups for nest boxes that were empty or previously occupied by a different taxon, we try to establish whether the relationships among them are commensal, mutualistic, competitive or amensal. Vertebrates and honeybees selected nest boxes that had previously been occupied by the other, which suggests that each obtains some benefit from the other. This relationship can be considered mutualistic, although a mutual preference for each others' nests does not exclude a competitive interaction. Vertebrates and wasps preferred nest boxes not previously occupied by the other, which suggests that they compete for tree cavities. Finally, wasps seemed to completely refuse cavities previously used by honeybees, while the bees occupied cavities regardless of whether they had been previously used by wasps, an apparently amensal relationship. These results indicate that the interdependence between distantly related taxa is stronger and more complex than previously described, which may have important implications for population dynamics and community structure.

Real estate ads in Emei music frog vocalizations: female preference for calls emanating from burrows.

PubMed

Cui, Jianguo; Tang, Yezhong; Narins, Peter M

2012-06-23

During female mate choice, both the male's phenotype and resources (e.g. his nest) contribute to the chooser's fitness. Animals other than humans are not known to advertise resource characteristics to potential mates through vocal communication; although in some species of anurans and birds, females do evaluate male qualities through vocal communication. Here, we demonstrate that calls of the male Emei music frog (Babina dauchina), vocalizing from male-built nests, reflect nest structure information that can be recognized by females. Inside-nest calls consisted of notes with energy concentrated at lower frequency ranges and longer note durations when compared with outside-nest calls. Centre frequencies and note durations of the inside calls positively correlate with the area of the burrow entrance and the depth of the burrow, respectively. When given a choice between outside and inside calls played back alternately, more than 70 per cent of the females (33/47) chose inside calls. These results demonstrate that males of this species faithfully advertise whether or not they possess a nest to potential mates by vocal communication, which probably facilitates optimal mate selection by females. These results revealed a novel function of advertisement calls, which is consistent with the wide variation in both call complexity and social behaviour within amphibians.

Fine-scale thermal adaptation in a green turtle nesting population

PubMed Central

Weber, Sam B.; Broderick, Annette C.; Groothuis, Ton G. G.; Ellick, Jacqui; Godley, Brendan J.; Blount, Jonathan D.

2012-01-01

The effect of climate warming on the reproductive success of ectothermic animals is currently a subject of major conservation concern. However, for many threatened species, we still know surprisingly little about the extent of naturally occurring adaptive variation in heat-tolerance. Here, we show that the thermal tolerances of green turtle (Chelonia mydas) embryos in a single, island-breeding population have diverged in response to the contrasting incubation temperatures of nesting beaches just a few kilometres apart. In natural nests and in a common-garden rearing experiment, the offspring of females nesting on a naturally hot (black sand) beach survived better and grew larger at hot incubation temperatures compared with the offspring of females nesting on a cooler (pale sand) beach nearby. These differences were owing to shallower thermal reaction norms in the hot beach population, rather than shifts in thermal optima, and could not be explained by egg-mediated maternal effects. Our results suggest that marine turtle nesting behaviour can drive adaptive differentiation at remarkably fine spatial scales, and have important implications for how we define conservation units for protection. In particular, previous studies may have underestimated the extent of adaptive structuring in marine turtle populations that may significantly affect their capacity to respond to environmental change. PMID:21937495

Characterisation of microbial communities in Chinese liquor fermentation starters Daqu using nested PCR-DGGE.

PubMed

Zhang, Liqiang; Wu, Chongde; Ding, Xiaofei; Zheng, Jia; Zhou, Rongqing

2014-12-01

In this study, characterises of the microbial community structures of three typical Chinese liquor Daqu, as well as different kinds of light flavour Daqu were investigated using nested PCR-denaturing gradient gel electrophoresis (DGGE). The results showed that microbial diversity was considerably different, and the microfloral compositions were highly variable among various Daqu. Lactic acid bacteria, which accounted for 30.95 % of all identified bacteria, were dominant in all Daqu samples, whereas Bacillus species were also predominant in the Luzhou (14.8 %) and Langjiu Daqu (18.2 %). Citrobacter and Burkholderia were first identified in light flavour Daqu. Aspergillus was the dominant moulds, and the non-Saccharomyces yeast species, Saccharomycopsis fibuligera, Wallemia sebi, Wallemia muriae, and Pichia subpelliculosa, were the dominant yeasts. Rasamsonia, Galactomyces, Geotrichum and Wallemia were first identified using nested PCR-DGGE. Cluster analysis indicated that the microbial community structures of different Daqu samples exhibited some differences. These may be ascribed to the different peak production temperatures, raw material constituents and microhabitats around the liquor enterprises. The current study provides insights into the microbial community structures of three typical Daqu samples, and may facilitate the development of starter cultures for manufacturing Chinese liquor.

Ecology and habitat of breeding Northern Goshawks in the inland Pacific Northwest: A summary of research in the 1990s

USGS Publications Warehouse

DeStefano, S.; McGrath, M.T.; Daw, S.K.; Desimone, S.M.

2006-01-01

During the 1990s, we conducted research on the distribution, productivity, and habitat relationships of Northern Goshawks (Accipiter gentilis) in eastern Oregon and Washington. Our research was initiated primarily in response to concerns raised about the status of Northern Goshawks in the western US, and coincided with early attempts to list the species as threatened or endangered under the Endangered Species Act and the publication of management guidelines for goshawks in the southwestern US. To develop baseline information on the status, distribution, and habitat relationships of goshawks in eastside forests (i.e., east of the Cascade Mountain Range) in the Pacific Northwest, we established study areas on three national forests in eastern Oregon in 1992, adding a fourth study area in central Washington in 1994. We focused on the breeding season and nesting habitat because of its primary importance to goshawk ecology and the logistical feasibility of finding nests. Density of breeding pairs ranged from 0.03-0.09/100 ha, and annual productivity ranged from 0.3-2.2 young fledged/nest. Goshawks selected forest stands with trees of larger diameter and greater canopy closure for nesting than available in the landscape. Occasionally nests could be found in large trees in open-canopied stands. As distance increased from the nest site, forest type and structure became more heterogeneous and the prevalence of older-seral-stage forest declined. Dry or wet openings were present in most territories, often within close proximity to nest stands. Goshawks ate a variety of mammalian and avian prey. Mammal species made up a larger portion of prey biomass on two of the national forests, but avian species appeared to be more prevalent in the diet of goshawks in the most northern study area. We recommend that the existing management guidelines for goshawks in the Southwest form a basis for management in the inland Pacific Northwest, particularly with regard to nested spatial concepts, emphasis on management of prey, and the use of silviculture to promote the development and replacement of old growth or late-seral-stage forest. Our research and management recommendations can be used in concert with the Southwestern management guidelines to establish a mix of vegetation structural stages to support goshawk populations, their prey, and other forest wildlife species specifically for the inland Pacific Northwest.

A Cladistic Analysis of Phenotypic Associations with Haplotypes Inferred from Restriction Endonuclease Mapping. IV. Nested Analyses with Cladogram Uncertainty and Recombination

PubMed Central

Templeton, A. R.; Sing, C. F.

1993-01-01

We previously developed an analytical strategy based on cladistic theory to identify subsets of haplotypes that are associated with significant phenotypic deviations. Our initial approach was limited to segments of DNA in which little recombination occurs. In such cases, a cladogram can be constructed from the restriction site data to estimate the evolutionary steps that interrelate the observed haplotypes to one another. The cladogram is then used to define a nested statistical design for identifying mutational steps associated with significant phenotypic deviations. The central assumption behind this strategy is that a mutation responsible for a particular phenotypic effect is embedded within the evolutionary history that is represented by the cladogram. The power of this approach depends on the accuracy of the cladogram in portraying the evolutionary history of the DNA region. This accuracy can be diminished both by recombination and by uncertainty in the estimated cladogram topology. In a previous paper, we presented an algorithm for estimating the set of likely cladograms and recombination events. In this paper we present an algorithm for defining a nested statistical design under cladogram uncertainty and recombination. Given the nested design, phenotypic associations can be examined using either a nested analysis of variance (for haploids or homozygous strains) or permutation testing (for outcrossed, diploid gene regions). In this paper we also extend this analytical strategy to include categorical phenotypes in addition to quantitative phenotypes. Some worked examples are presented using Drosophila data sets. These examples illustrate that having some recombination may actually enhance the biological inferences that may derived from a cladistic analysis. In particular, recombination can be used to assign a physical localization to a given subregion for mutations responsible for significant phenotypic effects. PMID:8100789

Chemosterilization of the sea lamprey (Petromyzon marinus)

USGS Publications Warehouse

Hanson, Lee H.; Manion, Patrick J.

1978-01-01

The chemical, P,P-bis(1-aziridinyl)-N-methylphosphinothioic amide (bisazir), was found in laboratory studies to be an effective sterilant for both sexes of adult sea lampreys (Petromyzon marinus) when given intraperitoneally at a dosage of 100 mg per kilogram of body weight. A total of 300 normal spawning-run sea lampreys and 300 injected with bisazir were released into the Big Garlic River, Marquette County, Michigan, (a small stream divided into five sections by natural barriers), to determine the effect of bisazir on the nesting and spawning behavior of the adults and on the production of larvae. The lampreys constructed and spawned in 95 nests. Sterile adults showed no abnormal nest building or spawning behavior. Sterile males competed effectively with normal males for females. Egg samples taken from nests indicated that eggs in nests where sterile males spawned with sterile or normal females did not hatch, although some embryonic development occurred. Extensive surveys with electric shockers produced no larvae in stream sections where sterile males spawned, but yielded numerous larvae in sections where normal males spawned with normal females. These findings suggest that the release of sterile males may be an effective tool in an integrated approach to control of sea lampreys in the Great Lakes.

Beyond harm’s reach? Submersion of river turtle nesting areas and implications for restoration actions after Amazon hydropower development

PubMed Central

Michalski, Fernanda; Gibbs, James P.

2018-01-01

The global expansion of energy demands combined with abundant rainfall, large water volumes and high flow in tropical rivers have led to an unprecedented expansion of dam constructions in the Amazon. This expansion generates an urgent need for refined approaches to river management; specifically a move away from decision-making governed by overly generalized guidelines. For the first time we quantify direct impacts of hydropower reservoir establishment on an Amazon fresh water turtle. We conducted surveys along 150 km of rivers upstream of a new dam construction during the low water months that correspond to the nesting season of Podocnemis unifilis in the study area. Comparison of nest-areas before (2011, 2015) and after (2016) reservoir filling show that reservoir impacts extend 13% beyond legally defined limits. The submerged nesting areas accounted for a total of 3.8 ha of nesting habitat that was inundated as a direct result of the reservoir filling in 2016. Our findings highlight limitations in the development and implementation of existing Brazilian environmental impact assessment process. We also propose potential ways to mitigate the negative impacts of dams on freshwater turtles and the Amazonian freshwater ecosystems they inhabit. PMID:29333347

Beyond harm's reach? Submersion of river turtle nesting areas and implications for restoration actions after Amazon hydropower development.

PubMed

Norris, Darren; Michalski, Fernanda; Gibbs, James P

2018-01-01

The global expansion of energy demands combined with abundant rainfall, large water volumes and high flow in tropical rivers have led to an unprecedented expansion of dam constructions in the Amazon. This expansion generates an urgent need for refined approaches to river management; specifically a move away from decision-making governed by overly generalized guidelines. For the first time we quantify direct impacts of hydropower reservoir establishment on an Amazon fresh water turtle. We conducted surveys along 150 km of rivers upstream of a new dam construction during the low water months that correspond to the nesting season of Podocnemis unifilis in the study area. Comparison of nest-areas before (2011, 2015) and after (2016) reservoir filling show that reservoir impacts extend 13% beyond legally defined limits. The submerged nesting areas accounted for a total of 3.8 ha of nesting habitat that was inundated as a direct result of the reservoir filling in 2016. Our findings highlight limitations in the development and implementation of existing Brazilian environmental impact assessment process. We also propose potential ways to mitigate the negative impacts of dams on freshwater turtles and the Amazonian freshwater ecosystems they inhabit.

A risk assessment approach to manage inundation of Elseya albagula nests in impounded waters: a win-win situation?

PubMed

McDougall, A J; Espinoza, T; Hollier, C; Limpus, D J; Limpus, C J

2015-03-01

A risk assessment process was used to trial the impact of potential new operating rules on the frequency of nest inundation for the White-throated snapping turtle, Elseya albagula, in the impounded waters of the Burnett River, Queensland, Australia. The proposed operating rules would increase the barrage storage level during the turtle nesting season (May-July) and then would be allowed to reduce to a lower level for incubation for the rest of the year. These proposed operating rules reduce rates of nest inundation by altering water levels in the Ben Anderson Barrage impoundment of the Burnett River. The rules operate throughout the turtle reproductive period and concomitantly improve stability of littoral habitat and fishway operation. Additionally, the proposed rules are expected to have positive socio-economic benefits within the region. While regulated water resources will inherently have a number of negative environmental implications, these potential new operating rules have the capacity to benefit the environment while managing resources in a more sustainable manner. The operating rules have now been enacted in subordinate legislation and require the operator to maintain water levels to minimize turtle nest inundation.

A Risk Assessment Approach to Manage Inundation of Elseya albagula Nests in Impounded Waters: A Win-Win Situation?

NASA Astrophysics Data System (ADS)

McDougall, A. J.; Espinoza, T.; Hollier, C.; Limpus, D. J.; Limpus, C. J.

2015-03-01

A risk assessment process was used to trial the impact of potential new operating rules on the frequency of nest inundation for the White-throated snapping turtle, Elseya albagula, in the impounded waters of the Burnett River, Queensland, Australia. The proposed operating rules would increase the barrage storage level during the turtle nesting season (May-July) and then would be allowed to reduce to a lower level for incubation for the rest of the year. These proposed operating rules reduce rates of nest inundation by altering water levels in the Ben Anderson Barrage impoundment of the Burnett River. The rules operate throughout the turtle reproductive period and concomitantly improve stability of littoral habitat and fishway operation. Additionally, the proposed rules are expected to have positive socio-economic benefits within the region. While regulated water resources will inherently have a number of negative environmental implications, these potential new operating rules have the capacity to benefit the environment while managing resources in a more sustainable manner. The operating rules have now been enacted in subordinate legislation and require the operator to maintain water levels to minimize turtle nest inundation.

Nested sparse grid collocation method with delay and transformation for subsurface flow and transport problems

NASA Astrophysics Data System (ADS)

Liao, Qinzhuo; Zhang, Dongxiao; Tchelepi, Hamdi

2017-06-01

In numerical modeling of subsurface flow and transport problems, formation properties may not be deterministically characterized, which leads to uncertainty in simulation results. In this study, we propose a sparse grid collocation method, which adopts nested quadrature rules with delay and transformation to quantify the uncertainty of model solutions. We show that the nested Kronrod-Patterson-Hermite quadrature is more efficient than the unnested Gauss-Hermite quadrature. We compare the convergence rates of various quadrature rules including the domain truncation and domain mapping approaches. To further improve accuracy and efficiency, we present a delayed process in selecting quadrature nodes and a transformed process for approximating unsmooth or discontinuous solutions. The proposed method is tested by an analytical function and in one-dimensional single-phase and two-phase flow problems with different spatial variances and correlation lengths. An additional example is given to demonstrate its applicability to three-dimensional black-oil models. It is found from these examples that the proposed method provides a promising approach for obtaining satisfactory estimation of the solution statistics and is much more efficient than the Monte-Carlo simulations.

Maximum likelihood estimation for Cox's regression model under nested case-control sampling.

PubMed

Scheike, Thomas H; Juul, Anders

2004-04-01

Nested case-control sampling is designed to reduce the costs of large cohort studies. It is important to estimate the parameters of interest as efficiently as possible. We present a new maximum likelihood estimator (MLE) for nested case-control sampling in the context of Cox's proportional hazards model. The MLE is computed by the EM-algorithm, which is easy to implement in the proportional hazards setting. Standard errors are estimated by a numerical profile likelihood approach based on EM aided differentiation. The work was motivated by a nested case-control study that hypothesized that insulin-like growth factor I was associated with ischemic heart disease. The study was based on a population of 3784 Danes and 231 cases of ischemic heart disease where controls were matched on age and gender. We illustrate the use of the MLE for these data and show how the maximum likelihood framework can be used to obtain information additional to the relative risk estimates of covariates.

Nested case-control studies: should one break the matching?

PubMed

Borgan, Ørnulf; Keogh, Ruth

2015-10-01

In a nested case-control study, controls are selected for each case from the individuals who are at risk at the time at which the case occurs. We say that the controls are matched on study time. To adjust for possible confounding, it is common to match on other variables as well. The standard analysis of nested case-control data is based on a partial likelihood which compares the covariates of each case to those of its matched controls. It has been suggested that one may break the matching of nested case-control data and analyse them as case-cohort data using an inverse probability weighted (IPW) pseudo likelihood. Further, when some covariates are available for all individuals in the cohort, multiple imputation (MI) makes it possible to use all available data in the cohort. In the paper we review the standard method and the IPW and MI approaches, and compare their performance using simulations that cover a range of scenarios, including one and two endpoints.

Swooping in the Suburbs; Parental Defence of an Abundant Aggressive Urban Bird against Humans.

PubMed

Lees, Daniel; Sherman, Craig D H; Maguire, Grainne S; Dann, Peter; Cardilini, Adam P A; Weston, Michael A

2013-08-13

Masked Lapwings, Vanellus miles, often come into 'conflict' with humans, because they often breed in close proximity to humans and actively defend their ground nests through aggressive behaviour, which typically involves swooping. This study examined whether defensive responses differed when nesting birds were confronted with different human stimuli ('pedestrian alone' vs. 'person pushing a lawn mower' approaches to nests) and tested the effectiveness of a commonly used deterrent (mock eyes positioned on the top or back of a person's head) on the defensive response. Masked Lapwings did not swoop closer to a person with a lawn mower compared with a pedestrian, but flushed closer and remained closer to the nest in the presence of a lawn mower. The presence of eye stickers decreased (pedestrians) and increased (lawn mowers) swooping behaviour. Masked Lapwings can discriminate between different human activities and adjust their defensive behaviour accordingly. We also conclude that the use of eye stickers is an effective method to mitigate the human-lapwing 'conflict' in some, but not all, circumstances.

Assessing conservation tools for an at-risk shorebird: Feasibility of headstarting for American Oystercatchers Haematopus palliatus

USGS Publications Warehouse

Collins, Samantha A.; Sanders, Felicia J.; Jodice, Patrick G.R.

2016-01-01

Management of threatened and endangered populations of wildlife increasingly relies upon active intervention such as predator control, habitat manipulation, and ex situ breeding or care. One tool that has received consideration for the management of declining or threatened avian populations is headstarting, or the artificial incubation of eggs and subsequent placement of newly hatched chicks in original or foster nests. We assessed the feasibility of implementing a headstarting program for the American Oystercatcher Haematopus palliatus, a species of high conservation concern in the eastern USA. Annual productivity is often low and lost during incubation, suggesting artificial incubation could enhance annual productivity. We used a control-impact approach to assign nests as either control or headstart and measured daily survival rate, success of parents accepting headstarted chicks, attendance patterns and behaviours of parents, and chick survival. We also implemented a transparent scoring process to rate the success of each step and the overall program. Daily survival rates of nests were significantly higher at headstart compared to control nests, and parents continued to incubate when eggs were well secured at nest sites. Attendance patterns and behaviour did not differ between headstart and control parents, and parents readily accepted healthy chicks whether they were returned to original or foster nests. Chick survival and subsequently annual productivity were, however, not higher at headstart compared to control nests suggesting that although we were able to enhance nest survival, low chick survival was still limiting annual productivity. Ultimately, headstarting may be most appropriate for American Oystercatchers where productivity is lost primarily to flooding, predation, or disturbance during the incubation stage but not during the chick-rearing stage. If, for example, high rates of nest loss are due to predators that also may prey upon chicks, then headstarting may not be an effective conservation tool.

Psychiatric comorbidity may not predict suicide during and after hospitalization. A nested case-control study with blinded raters.

PubMed

Walby, Fredrik A; Odegaard, Erik; Mehlum, Lars

2006-06-01

To investigate the differential impact of DSM-IV axis-I and axis-II disorders on completed suicide and to study if psychiatric comorbidity increases the risk of suicide in currently and previously hospitalized psychiatric patients. A nested case-control design based on case notes from 136 suicides and 166 matched controls. All cases and controls were rediagnosed using the SCID-CV for axis-I and the DSM-IV criteria for axis-II disorders and the inter-rater reliability was satisfactory. Raters were blind to the case and control status and the original hospital diagnoses. Depressive disorders and bipolar disorders were associated with an increased risk of suicide. No such effect was found for comorbidity between axis-I disorders and for comorbidity between axis-I and axis-II disorders. Psychiatric diagnoses, although made using a structured and criteria-based approach, was based on information recorded in case notes. Axis-II comorbidity could only be investigated at an aggregated level. Psychiatric comorbidity did not predict suicide in this sample. Mood disorders did, however, increase the risk significantly independent of history of previous suicide attempts. Both findings can inform identification and treatment of patients at high risk for completed suicide.

Electromagnetic field enhancement and spectrum shaping through plasmonically integrated optical vortices.

PubMed

Ahn, Wonmi; Boriskina, Svetlana V; Hong, Yan; Reinhard, Björn M

2012-01-11

We introduce a new design approach for surface-enhanced Raman spectroscopy (SERS) substrates that is based on molding the optical powerflow through a sequence of coupled nanoscale optical vortices "pinned" to rationally designed plasmonic nanostructures, referred to as Vortex Nanogear Transmissions (VNTs). We fabricated VNTs composed of Au nanodiscs by electron beam lithography on quartz substrates and characterized their near- and far-field responses through combination of computational electromagnetism, and elastic and inelastic scattering spectroscopy. Pronounced dips in the far-field scattering spectra of VNTs provide experimental evidence for an efficient light trapping and circulation within the nanostructures. Furthermore, we demonstrate that VNT integration into periodic arrays of Au nanoparticles facilitates the generation of high E-field enhancements in the VNTs at multiple defined wavelengths. We show that spectrum shaping in nested VNT structures is achieved through an electromagnetic feed-mechanism driven by the coherent multiple scattering in the plasmonic arrays and that this process can be rationally controlled by tuning the array period. The ability to generate high E-field enhancements at predefined locations and frequencies makes nested VNTs interesting substrates for challenging SERS applications. © 2011 American Chemical Society

Reproductive plasticity and landscape heterogeneity benefit a ground-nesting bird in a fire-prone ecosystem.

PubMed

Carroll, J Matthew; Hovick, Torre J; Davis, Craig A; Elmore, Robert Dwayne; Fuhlendorf, Samuel D

2017-10-01

Disturbance is critical for the conservation of rangeland ecosystems worldwide and many of these systems are fire dependent. Although it is well established that restoring fire as an ecological process can lead to increased biodiversity in grasslands and shrublands, the underlying mechanisms driving community patterns are poorly understood for fauna in fire-prone landscapes. Much of this uncertainty stems from the paucity of studies that examine the effects of fire at scales relevant to organism life histories. We assessed the response of a non-migratory ground-dwelling bird to disturbance (i.e., prescribed fire) and environmental stochasticity over the course of a 4-yr period, which spanned years of historic drought and record rainfall. Specifically, we investigated the nesting ecology of Northern Bobwhite (Colinus virginianus; hereafter Bobwhite) to illuminate possible avenues by which individuals respond to dynamic landscape patterns during a critical reproductive stage (i.e., nesting) in a mixed-grass shrubland in western Oklahoma, USA. We found that Bobwhites exhibited extreme plasticity in nest substrate use among time since fire categories (TSF) and subsequently maintained high nest survival (e.g., 57-70%). Bobwhites were opportunistic in nest substrate use among TSF categories (i.e., 72% of nest sites in shrubs in 0-12 months post fire compared to 71% in herbaceous vegetation in >36 months post fire), yet nesting decisions were first filtered by similar structural components (i.e., vertical and horizontal cover) within the vicinity of nest sites regardless of TSF category. Despite being a non-migratory and comparatively less mobile ground-nesting bird species, Bobwhites adjusted to dynamic vegetation mosaics on a fire-prone landscape under stochastic climatic conditions that culminated in stable and high nest survival. Broadly, our findings provide a unique depiction of organism response strategies to fire at scales relevant to a critical life-stage, a topic that has been previously understudied and poorly understood. We also demonstrate how doing so can better inform conservation practices aimed at restoring fire regimes on grassland and shrubland landscapes. © 2017 by the Ecological Society of America.

Bird on the wire: Landscape planning considering costs and benefits for bird populations coexisting with power lines.

PubMed

D'Amico, Marcello; Catry, Inês; Martins, Ricardo C; Ascensão, Fernando; Barrientos, Rafael; Moreira, Francisco

2018-02-24

Power-line grids are increasingly expanding worldwide, as well as their negative impacts on avifauna, namely the direct mortality through collision and electrocution, the reduction of breeding performance, and the barrier effect. On the other hand, some bird species can apparently benefit from the presence of power lines, for example perching for hunting purposes or nesting on electricity towers. In this perspective essay, we reviewed the scientific literature on both costs and benefits for avifauna coexisting with power lines. Overall, we detected a generalized lack of studies focusing on these costs or benefits at a population level. We suggest that a switch in research approach to a larger spatio-temporal scale would greatly improve our knowledge about the actual effects of power lines on bird populations. This research approach would facilitate suitable landscape planning encompassing both mitigation of costs and promotion of benefits for bird populations coexisting with power lines. For example, the strategic route planning of electricity infrastructures would limit collision risk or barrier effects for threatened bird populations. Concurrently, this strategic route planning would promote the range expansion of threatened populations of other bird species, by providing nesting structures in treeless but potentially suitable landscapes. We suggest establishing a collaborative dialogue among the scientific community, governments, and electricity companies, with the aim to produce a win-win scenario in which both biodiversity conservation and infrastructure development are integrated in a common strategy.

Identifying three-dimensional nested groundwater flow systems in a Tóthian basin

NASA Astrophysics Data System (ADS)

Wang, Xu-Sheng; Wan, Li; Jiang, Xiao-Wei; Li, Hailong; Zhou, Yangxiao; Wang, Junzhi; Ji, Xiaohui

2017-10-01

Nested groundwater flow systems have been revealed in Tóth's theory as the structural property of basin-scale groundwater circulation but were only well known with two-dimensional (2D) profile models. The method of searching special streamlines across stagnation points for partitioning flow systems, which has been successfully applied in the 2D models, has never been implemented for three-dimensional (3D) Tóthian basins because of the difficulty in solving the dual stream functions. Alternatively, a new method is developed to investigate 3D nested groundwater flow systems without determination of stagnation points. Connective indices are defined to quantify the connection between individual recharge and discharge zones along streamlines. Groundwater circulation cells (GWCCs) are identified according to the distribution of the connective indices and then grouped into local, intermediate and regional flow systems. This method requires existing solution of the flow velocity vector and is implemented via particle tracking technique. It is applied in a hypothetical 3D Tóthian basin with an analytical solution of the flow field and in a real-world basin with a numerical modeling approach. Different spatial patterns of flow systems compared to 2D profile models are found. The outcrops boundaries of GWCCs on water table may significantly deviate from and are not parallel to the nearby water table divides. Topological network is proposed to represent the linked recharge-discharge zones through closed and open GWCCs. Sensitivity analysis indicates that the development of GWCCs depends on the basin geometry, hydraulic parameters and water table shape.

Comparison of PCR primer-based strategies for characterization of ammonia oxidizer communities in environmental samples.

PubMed

Mahmood, Shahid; Freitag, Thomas E; Prosser, James I

2006-06-01

PCR-based techniques are commonly used to characterize microbial communities, but are subject to bias that is difficult to assess. This study aimed to evaluate bias of several PCR primer-based strategies used to study diversity of autotrophic ammonia oxidizers. 16S rRNA genes from soil- or sediment-DNA were amplified using primers considered either selective or specific for betaproteobacterial ammonia oxidizers. Five approaches were assessed: (a) amplification with primers betaAMO143f-betaAMO1315r; (b) amplification with primers CTO189f-CTO654r; (c) nested amplification with betaAMO143f-betaAMO1315r followed by CTO189f-CTO654r primers; (d) nested amplification with betaAMO143f-betaAMO1315r and CTO189f-Pf1053r primers; (e) nested amplification with 27f-1492r and CTO189f-CTO654r primers. Amplification products were characterized by denaturing gradient gel electrophoresis (DGGE) analysis after further amplification with 357f-GC-518r primers. DGGE profiles of soil communities were heterogeneous and depended on the approach followed. Ammonia oxidizer diversity was higher using approaches (b), (c) and (e) than using (a) and (d), where sequences of the most prominent bands showed similarities to nonammonia oxidizers. Profiles from marine sediments were more consistent, regardless of the approach adopted, and sequence analysis of excised bands indicated that these consisted of ammonia oxidizers only. The study demonstrates the importance of choice of primer, of screening for sequences of nontarget organisms and use of several approaches when characterizing microbial communities in natural environments.

[Recent fauna of ground-nesting birds in Transvolga steppes and its dynamics in the 20th century].

PubMed

Oparin, M L

2008-01-01

It is shown that the structure of the ground-nesting bird fauna in Transvolga steppes has changed during the 20th century. The complex of lark species characteristic of true and dry steppe has disappeared because of climate change and impact of economic activity (the establishment of windbreak and roadside forest strips), which has provided for a sharp increase in the abundance of corvid birds.

Seabird nest counts: A test of monitoring metrics using Red-tailed Tropicbirds

USGS Publications Warehouse

Seavy, N.E.; Reynolds, M.H.

2009-01-01

Counts of nesting birds are often used to monitor the abundance of breeding pairs at colonies. Mean incubation counts (MICs) are counts of nests with eggs at intervals that correspond to the mean incubation period of a species. The sum of all counts during the nesting season (MICtotal) and the highest single count during the season (MICmax) are metrics that can be generated from this method. However, the utility of these metrics as measures of the number of breeding pairs has not been well tested. We used two approaches to evaluate the bias and precision of MIC metrics for quantifying annual variation in the number of breeding Red-tailed Tropicbirds (Phaethon rubricauda) nesting on two islands in the Papahnaumokukea Marine National Monument in the northwest Hawaiian Islands. First, we used data from nest plots with individually marked birds to generate simulated MIC metrics that we compared to the known number of nesting individuals. The MICtotal overestimated the number of pairs by about 5%, whereas the MICmax underestimated the number of pairs by about 60%. However, both metrics exhibited similar precision. Second, we used a 12-yr time series of island-wide MICs to compare estimates of temporal trend and annual variation using the MICmax and MICtotal. The 95% confidence intervals for the trend estimates were overlapping and the residual standard errors for the two metrics were similar. Our results suggest that both metrics offered similar precision for indices of breeding pairs of Red-tailed Tropicbirds, but that MICtotal was more accurate. ?? 2009 Association of Field Ornithologists.

Foraging and nesting habitat of breeding male northern goshawks in the laurentian mixed forest province, Minnesota

USGS Publications Warehouse

Boal, C.W.; Andersen, D.E.; Kennedy, P.L.

2005-01-01

We used radiotelemetry to examine foraging habitat preferences of 17 breeding, male northern goshawks (Accipiter gentilis) in Minnesota from 1998-2000. We assessed habitat preference using radio relocation points and 50-m radius buffers of radio relocation points. Our data suggested that foraging male goshawks used early-successional upland conifer stands (???25 yrs old), early-successional upland deciduous stands (???50 yrs old), late-successional upland conifer stands (???50 yrs old), and late-successional upland deciduous stands (???50 yrs old) more frequently than expected based on the abundance of these vegetation types in the landscape. The 2 most available stand types, early-successional upland deciduous (<25 yrs old) and all ages of late-successional lowland conifer stands, were used less than expected by foraging goshawks. Late-successional lowland deciduous stands (???50 yrs old) were used in proportion to availability. Although analysis of relocation points suggested early-successional upland deciduous stands (25-49 yrs old) and late-successional upland conifer stands (???50 yrs old) were used in proportion to availability, analysis of buffers around relocation points indicated that these stand types were also used more than expected by foraging goshawks. Regardless of vegetation community type, stands used by goshawks were structurally similar with high canopy and understory stem densities, high canopy closure, substantial shrub cover, and large amounts of woody debris. Nest stands consisted of taller and larger diameter canopy trees and fewer understory trees than foraging stands, but stands were otherwise similar in structural features, suggesting goshawks used similar stands for nesting and foraging but that they tended to select the most mature stands for nesting. A commonality among nesting and foraging stands was the presence of open spaces between the canopy and understory foliage, and between understory and shrub layer foliage. In our study area, these spaces may have served as relatively unobstructed flight paths where foraging and nesting stands possessed stem densities at the upper end of that reported for goshawk habitat.

A Language-Based Approach To Wireless Sensor Network Security

DTIC Science & Technology

2014-03-06

128 – RPC 119 7.0 Secure RPC 87 32.0 Figure 1: SpartanRPC Memory Overhead (L) and Impact on Messaging (R) Figure 2: Scalaness /nesT Compilation and...language for developing real WSN applica- tions. This language, called Scalaness /nesT, extends Scala with staging features for executing programs on hubs...particular note here is the fact that cross-stage type safety of Scalaness source code ensures that compiled bytecode can be deployed to, and run on

The importance of scale-dependent ravine characteristics on breeding-site selection by the Burrowing Parrot, Cyanoliseus patagonus

PubMed Central

Rios, Rodrigo S.; Vargas-Rodriguez, Renzo; Novoa-Jerez, Jose-Enrique; Squeo, Francisco A.

2017-01-01

In birds, the environmental variables and intrinsic characteristics of the nest have important fitness consequences through its influence on the selection of nesting sites. However, the extent to which these variables interact with variables that operate at the landscape scale, and whether there is a hierarchy among the different scales that influences nest-site selection, is unknown. This interaction could be crucial in burrowing birds, which depend heavily on the availability of suitable nesting locations. One representative of this group is the burrowing parrot, Cyanoliseus patagonus that breeds on specific ravines and forms large breeding colonies. At a particular site, breeding aggregations require the concentration of adequate environmental elements for cavity nesting, which are provided by within ravine characteristics. Therefore, intrinsic ravine characteristics should be more important in determining nest site selection compared to landscape level characteristics. Here, we assess this hypothesis by comparing the importance of ravine characteristics operating at different scales on nest-site selection and their interrelation with reproductive success. We quantified 12 characteristics of 105 ravines in their reproductive habitat. For each ravine we quantified morphological variables, distance to resources and disturbance as well as nest number and egg production in order to compare selected and non-selected ravines and determine the interrelationship among variables in explaining ravine differences. In addition, the number of nests and egg production for each reproductive ravine was related to ravine characteristics to assess their relation to reproductive success. We found significant differences between non-reproductive and reproductive ravines in both intrinsic and extrinsic characteristics. The multidimensional environmental gradient of variation between ravines, however, shows that differences are mainly related to intrinsic morphological characteristics followed by extrinsic variables associated to human disturbance. Likewise, within reproductive ravines, intrinsic characteristics are more strongly related to the number of nests. The probability of producing eggs, however, was related only to distance to roads and human settlements. Patterns suggest that C. patagonus mainly selects nesting sites based on intrinsic morphological characteristics of ravines. Scale differences in the importance of ravine characteristics could be a consequence of the particular orography of the breeding habitat. The arrangement of resources is associated to the location of the gullies rather than to individual ravines, determining the spatial availability and disposition of resources and disturbances. Thus, nest selection is influenced by intrinsic characteristics that maximize the fitness of individuals. Scaling in nest-selection is discussed under an optimality approach that partitions patch selection based on foraging theory. PMID:28462019

Age-related differences in nest defense in common terns: Relationship to other life-history parameters.

PubMed

Pearson, Jennifer; Nisbet, Ian C T; Ottinger, Mary Ann

2005-12-01

The Common Tern (Sterno hirundo) is a long-lived colonial nesting seabird. Previous studies have shown that chick growth and fledging success vary with age of the parental pair and with laying date, with older parents and those nesting earlier being more successful. This study investigated the dependence of breeding performance and one aspect of behavior, defense against conspecifics, on age and laying date. Nest defense behavior was evaluated by recording individual responses to a mirror placed 20 cm from the nest, simulating an unfamiliar intruder within the territory. Most study birds were of known age (3-21 years) from banding as chicks; they were divided into three groups: ≥12, 8-11 and ≤seven years. Responses to the mirror were examined during incubation and at the time of hatching. Older birds nested earlier than younger birds. Chicks reared by older parents gained mass more quickly and survived better than chicks of younger parents. Using a composite score reflecting both the intensity and duration of aggressive responses to the mirror, older birds responded more strongly than younger birds during incubation, but responses were similar at the time of hatching. Older birds reduced their aggressive responses between incubation and hatching, while younger birds increased their responses. We suggest that this contributes to the greater success of older birds, because younger birds expend more time and energy on territorial defense at a time when they need to feed chicks. Our findings are consistent with previous studies and show that Common Tern colonies are finely structured by age and laying date; older and earlier-nesting birds are superior to younger and later birds on several measures of performance. This study suggests that finely-tuned nest defense behavior is one component of the superior performance of old birds.

Multi-scale habitat selection in highly territorial bird species: Exploring the contribution of nest, territory and landscape levels to site choice in breeding rallids (Aves: Rallidae)

NASA Astrophysics Data System (ADS)

Jedlikowski, Jan; Chibowski, Piotr; Karasek, Tomasz; Brambilla, Mattia

2016-05-01

Habitat selection often involves choices made at different spatial scales, but the underlying mechanisms are still poorly understood, and studies that investigate the relative importance of individual scales are rare. We investigated the effect of three spatial scales (landscape, territory, nest-site) on the occurrence pattern of little crake Zapornia parva and water rail Rallus aquaticus at 74 ponds in the Masurian Lakeland, Poland. Habitat structure, food abundance and water chemical parameters were measured at nests and random points within landscape plots (from 300-m to 50-m radius), territory (14-m) and nest-site plots (3-m). Regression analyses suggested that the most relevant scale was territory level, followed by landscape, and finally by nest-site for both species. Variation partitioning confirmed this pattern for water rail, but also highlighted the importance of nest-site (the level explaining the highest share of unique variation) for little crake. The most important variables determining the occurrence of both species were water body fragmentation (landscape), vegetation density (territory) and water depth (at territory level for little crake, and at nest-site level for water rail). Finally, for both species multi-scale models including factors from different levels were more parsimonious than single-scale ones, i.e. habitat selection was likely a multi-scale process. The importance of particular spatial scales seemed more related to life-history traits than to the extent of the scales considered. In the case of our study species, the territory level was highly important likely because both rallids have to obtain all the resources they need (nest site, food and mates) in relatively small areas, the multi-purpose territories they defend.

76 FR 34576 - Amendment of Class E Airspace; Waynesboro, VA

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-14

... Waynesboro, VA, to accommodate the additional airspace need for the Standard Instrument Approach Procedures developed for Eagle's Nest Airport. This action enhances the safety and management of Instrument Flight... upward from 700 feet above the surface to accommodate new standard instrument approach procedures...

Molecular phylogeny supports the paraphyletic nature of the genus Trogoderma (Coleoptera: Dermestidae) collected in the Australasian ecozone.

PubMed

Castalanelli, M A; Baker, A M; Munyard, K A; Grimm, M; Groth, D M

2012-02-01

To date, a molecular phylogenetic approach has not been used to investigate the evolutionary structure of Trogoderma and closely related genera. Using two mitochondrial genes, Cytochrome Oxidase I and Cytochrome B, and the nuclear gene, 18S, the reported polyphyletic positioning of Trogoderma was examined. Paraphyly in Trogoderma was observed, with one Australian Trogoderma species reconciled as sister to all Dermestidae and the Anthrenocerus genus deeply nested within the Australian Trogoderma clade. In addition, time to most recent common ancestor for a number of Dermestidae was calculated. Based on these estimations, the Dermestidae origin exceeded 175 million years, placing the origins of this family in Pangaea.

Examining Competing Models of Transformational Leadership, Leadership Trust, Change Commitment, and Job Satisfaction.

PubMed

Yang, Yi-Feng

2016-08-01

This study discusses the influence of transformational leadership on job satisfaction through assessing six alternative models related to the mediators of leadership trust and change commitment utilizing a data sample (N = 341; M age = 32.5 year, SD = 5.2) for service promotion personnel in Taiwan. The bootstrap sampling technique was used to select the better fitting model. The tool of hierarchical nested model analysis was applied, along with the approaches of bootstrapping mediation, PRODCLIN2, and structural equation modeling comparison. The results overall demonstrate that leadership is important and that leadership role identification (trust) and workgroup cohesiveness (commitment) form an ordered serial relationship. © The Author(s) 2016.

Individual quality, survival variation and patterns of phenotypic selection on body condition and timing of nesting in birds

USGS Publications Warehouse

Blums, P.; Nichols, J.D.; Hines, J.E.; Lindberg, M.; Mednis, A.

2005-01-01

Questions about individual variation in 'quality' and fitness are of great interest to evolutionary and population ecologists. Such variation can be investigated using either a random effects approach or an approach that relies on identifying observable traits that are themselves correlated with fitness components. We used the latter approach with data from 1,925 individual females of three species of ducks (tufted duck, Aythya fuligula; common pochard, Aythya ferina; northern shoveler, Anas clypeata) sampled on their breeding grounds at Engure Marsh, Latvia, for over 15 years. Based on associations with reproductive output, we selected two traits, one morphological (relative body condition) and one behavioral (relative time of nesting), that can be used to characterize individual females over their lifetimes. We then asked whether these traits were related to annual survival probabilities of nesting females. We hypothesized quadratic, rather than monotonic, relationships based loosely on ideas about the likely action of stabilizing selection on these two traits. Parameters of these relationships were estimated directly using ultrastructural models embedded within capture-recapture-band-recovery models. Results provided evidence that both traits were related to survival in the hypothesized manner. For all three species, females that tended to nest earlier than the norm exhibited the highest survival rates, but very early nesters experienced reduced survival and late nesters showed even lower survival. For shovelers, females in average body condition showed the highest survival, with lower survival rates exhibited by both heavy and light birds. For common pochard and tufted duck, the highest survival rates were associated with birds of slightly above-average condition, with somewhat lower survival for very heavy birds and much lower survival for birds in relatively poor condition. Based on results from this study and previous work on reproduction, we conclude that nest initiation date and body condition covary with both reproductive and survival components of fitness. These associations lead to a positive covariance of these two fitness components within individuals and to the conclusion that these two traits are indeed correlates of individual quality.

Assessing power of large river fish monitoring programs to detect population changes: the Missouri River sturgeon example

USGS Publications Warehouse

Wildhaber, M.L.; Holan, S.H.; Bryan, J.L.; Gladish, D.W.; Ellersieck, M.

2011-01-01

In 2003, the US Army Corps of Engineers initiated the Pallid Sturgeon Population Assessment Program (PSPAP) to monitor pallid sturgeon and the fish community of the Missouri River. The power analysis of PSPAP presented here was conducted to guide sampling design and effort decisions. The PSPAP sampling design has a nested structure with multiple gear subsamples within a river bend. Power analyses were based on a normal linear mixed model, using a mixed cell means approach, with variance estimates from the original data. It was found that, at current effort levels, at least 20 years for pallid and 10 years for shovelnose sturgeon is needed to detect a 5% annual decline. Modified bootstrap simulations suggest power estimates from the original data are conservative due to excessive zero fish counts. In general, the approach presented is applicable to a wide array of animal monitoring programs.

Community-Based Equity Audits: A Practical Approach for Educational Leaders to Support Equitable Community-School Improvements

ERIC Educational Resources Information Center

Green, Terrance L.

2017-01-01

Purpose: To equitably transform urban schools of color and the neighborhoods where they are nested requires approaches that promote community equity and foster solidarity among a range of stakeholders. However, most school-community approaches solely focus on improving school-based outcomes and leave educational leaders with little guidance for…

Factors affecting hatch success of hawksbill sea turtles on Long Island, Antigua, West Indies.

PubMed

Ditmer, Mark Allan; Stapleton, Seth Patrick

2012-01-01

Current understanding of the factors influencing hawksbill sea turtle (Eretmochelys imbricata) hatch success is disparate and based on relatively short-term studies or limited sample sizes. Because global populations of hawksbills are heavily depleted, evaluating the parameters that impact hatch success is important to their conservation and recovery. Here, we use data collected by the Jumby Bay Hawksbill Project (JBHP) to investigate hatch success. The JBHP implements saturation tagging protocols to study a hawksbill rookery in Antigua, West Indies. Habitat data, which reflect the varied nesting beaches, are collected at egg deposition, and nest contents are exhumed and categorized post-emergence. We analyzed hatch success using mixed-model analyses with explanatory and predictive datasets. We incorporated a random effect for turtle identity and evaluated environmental, temporal and individual-based reproductive variables. Hatch success averaged 78.6% (SD: 21.2%) during the study period. Highly supported models included multiple covariates, including distance to vegetation, deposition date, individual intra-seasonal nest number, clutch size, organic content, and sand grain size. Nests located in open sand were predicted to produce 10.4 more viable hatchlings per clutch than nests located >1.5 m into vegetation. For an individual first nesting in early July, the fourth nest of the season yielded 13.2 more viable hatchlings than the initial clutch. Generalized beach section and inter-annual variation were also supported in our explanatory dataset, suggesting that gaps remain in our understanding of hatch success. Our findings illustrate that evaluating hatch success is a complex process, involving multiple environmental and individual variables. Although distance to vegetation and hatch success were inversely related, vegetation is an important component of hawksbill nesting habitat, and a more complete assessment of the impacts of specific vegetation types on hatch success and hatchling sex ratios is needed. Future research should explore the roles of sand structure, nest moisture, and local weather conditions.

The First Occurrence in the Fossil Record of an Aquatic Avian Twig-Nest with Phoenicopteriformes Eggs: Evolutionary Implications

PubMed Central

Grellet-Tinner, Gerald; Murelaga, Xabier; Larrasoaña, Juan C.; Silveira, Luis F.; Olivares, Maitane; Ortega, Luis A.; Trimby, Patrick W.; Pascual, Ana

2012-01-01

Background We describe the first occurrence in the fossil record of an aquatic avian twig-nest with five eggs in situ (Early Miocene Tudela Formation, Ebro Basin, Spain). Extensive outcrops of this formation reveal autochthonous avian osteological and oological fossils that represent a single taxon identified as a basal phoenicopterid. Although the eggshell structure is definitively phoenicopterid, the characteristics of both the nest and the eggs are similar to those of modern grebes. These observations allow us to address the origin of the disparities between the sister taxa Podicipedidae and Phoenicopteridae crown clades, and traces the evolution of the nesting and reproductive environments for phoenicopteriforms. Methodology/Principal Findings Multi-disciplinary analyses performed on fossilized vegetation and eggshells from the eggs in the nest and its embedding sediments indicate that this new phoenicopterid thrived under a semi-arid climate in an oligohaline (seasonally mesohaline) shallow endorheic lacustine environment. High-end microcharacterizations including SEM, TEM, and EBSD techniques were pivotal to identifying these phoenicopterid eggshells. Anatomical comparisons of the fossil bones with those of Phoenicopteriformes and Podicipediformes crown clades and extinct palaelodids confirm that this avian fossil assemblage belongs to a new and basal phoenicopterid. Conclusions/Significance Although the Podicipediformes-Phoenicopteriformes sister group relationship is now well supported, flamingos and grebes exhibit feeding, reproductive, and nesting strategies that diverge significantly. Our multi-disciplinary study is the first to reveal that the phoenicopteriform reproductive behaviour, nesting ecology and nest characteristics derived from grebe-like type strategies to reach the extremely specialized conditions observed in modern flamingo crown groups. Furthermore, our study enables us to map ecological and reproductive characters on the Phoenicopteriformes evolutionary lineage. Our results demonstrate that the nesting paleoenvironments of flamingos were closely linked to the unique ecology of this locality, which is a direct result of special climatic (high evaporitic regime) and geological (fault system) conditions. PMID:23082136

Factors Affecting Hatch Success of Hawksbill Sea Turtles on Long Island, Antigua, West Indies

PubMed Central

Ditmer, Mark Allan; Stapleton, Seth Patrick

2012-01-01

Current understanding of the factors influencing hawksbill sea turtle (Eretmochelys imbricata) hatch success is disparate and based on relatively short-term studies or limited sample sizes. Because global populations of hawksbills are heavily depleted, evaluating the parameters that impact hatch success is important to their conservation and recovery. Here, we use data collected by the Jumby Bay Hawksbill Project (JBHP) to investigate hatch success. The JBHP implements saturation tagging protocols to study a hawksbill rookery in Antigua, West Indies. Habitat data, which reflect the varied nesting beaches, are collected at egg deposition, and nest contents are exhumed and categorized post-emergence. We analyzed hatch success using mixed-model analyses with explanatory and predictive datasets. We incorporated a random effect for turtle identity and evaluated environmental, temporal and individual-based reproductive variables. Hatch success averaged 78.6% (SD: 21.2%) during the study period. Highly supported models included multiple covariates, including distance to vegetation, deposition date, individual intra-seasonal nest number, clutch size, organic content, and sand grain size. Nests located in open sand were predicted to produce 10.4 more viable hatchlings per clutch than nests located >1.5 m into vegetation. For an individual first nesting in early July, the fourth nest of the season yielded 13.2 more viable hatchlings than the initial clutch. Generalized beach section and inter-annual variation were also supported in our explanatory dataset, suggesting that gaps remain in our understanding of hatch success. Our findings illustrate that evaluating hatch success is a complex process, involving multiple environmental and individual variables. Although distance to vegetation and hatch success were inversely related, vegetation is an important component of hawksbill nesting habitat, and a more complete assessment of the impacts of specific vegetation types on hatch success and hatchling sex ratios is needed. Future research should explore the roles of sand structure, nest moisture, and local weather conditions. PMID:22802928

Preliminary analysis of Greater Sage-grouse reproduction in the Virginia Mountains of northwestern Nevada

USGS Publications Warehouse

Coates, Peter S.; Lockyer, Zachary B.; Farinha, Melissa A.; Sweeney, Joelle M.; Johnson, Valerie M.; Meshriy, Matthew G.; Espinosa, Shawn P.; Delehanty, David J.; Casazza, Michael L.

2011-01-01

Relationships between habitat selection and population vital rates of greater sage-grouse (Centrocercus urophasianus; hereafter sage-grouse), recently designated as a candidate species under the Endangered Species Act, within the Great Basin are not well-understood. The growing development of renewable energy infrastructure within areas inhabited by sage-grouse is thought to influence predator and vegetation communities. For example, common ravens (Corvus corax), a synanthropic sage-grouse nest predator, are increasing range-wide and select transmission lines and other tall structures for nesting and perching. In the Virginia Mountains of northwestern Nevada, we collected preliminary information of space-use, habitat selection, and population vital rates during the nesting and brood-rearing period over two years on 56 sage-grouse. Additionally, videography at nest sites (n = 22) was used to identify sage-grouse nest predators. The study area is a potential site for renewable energy developments (i.e., wind and solar), and we plan to continue monitoring this population using a before-after-control-impact study design. The results reported here are preliminary and further data are required before conclusions can be drawn from this population of sage-grouse.

Microclimate and nest-site selection in Micronesian Kingfishers

USGS Publications Warehouse

Kesler, Dylan C.; Haig, Susan M.

2005-01-01

We studied the relationship between microclimate and nest-site selection in the Pohnpei Micronesian Kingfisher (Todiramphus cinnamominus reichenbachii) which excavates nest cavities from the mudlike nest structures of arboreal termites (Nasutitermes sp.) or termitaria. Mean daily high temperatures at termitaria were cooler and daily low temperatures were warmer than at random sites in the forest. Results also indicate that termitaria provided insulation from temperature extremes, and that temperatures inside termitaria were within the thermoneutral zone of Micronesian Kingfishers more often than those outside. No differences were identified in temperatures at sites where nest termitaria and nonnest termitaria occurred or among the insulation properties of used and unused termitaria. These results suggest that although termitaria provide insulation from thermal extremes and a metabolically less stressful microclimate, king-fishers did not select from among available termitaria based on their thermal properties. Our findings are relevant to conservation efforts for the critically endangered Guam Micronesian Kingfisher (T. c. cinnamominus) which is extinct in the wild and exists only as a captive population. Captive breeding facilities should provide aviaries with daily ambient temperatures ranging from 22.06 A?C to 28.05 A?C to reduce microclimate-associated metabolic stress and to replicate microclimates used by wild Micronesian Kingfishers.

Compilation of 1990 annual reports of the Navy ELF Communications System Ecological-Monitoring Program. Volume 2. Tabs C thru F. Annual report, Jan-Dec 90

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

Zapotosky, J.E.

1991-08-01

This portion of the report includes monitoring of and data for arthropoda and earthworms; pollinating insects; and small mammals and nesting birds. During the 1990 growing season the ELF antenna was operated more frequently than in prior years. This provides 2 years of intermittent ELF exposure for the biological systems to react to the radiation, one year of very limited exposure and greater exposure in 1990. Arthropod and earthworm sampling was conducted at intervals of two weeks from early May to late October. High voltage transmission lines and magnetic fields have been shown to affect honeybee reproduction, survival, orientation, andmore » nest structure. ELF EM fields could have similar effects on native megachild bees. Changes in cell length, number of cells per nest, number of leaver per cell, orientation of nest entrances, and time to collect a round leaf pierce to cap a cell were monitored. We have not detected significant changes that could be attributed to ELF EM fields. Small mammal and nesting bird biological studies in the western Upper Peninsula of Michigan for the year 1990 are reported.« less

Taxonomy and ecology of a new species of Corynura (Hymenoptera: Halictidae: Augochlorini) from Chile and Argentina.

PubMed

González-Vaquero, Rocío Ana; Polidori, Carlo; Nieves-Aldrey, José Luis

2017-01-16

We describe a new species of Corynura Spinola, a socially polymorphic genus within the bee tribe Augochlorini (Halictidae). We present a detailed description of both sexes of Corynura (Corynura) moscosensis n. sp. González-Vaquero, images of diagnostic morphological structures and antennal sensilla, floral associations, distributional data and notes on its nesting biology. Corynura moscosensis n. sp. is similar in appearance to C. (C.) chloromelas (Alfken), but it can be distinguished by the sculpturing of the mesoscutum and the hair types on the propodeum in the female, and by the genitalia and extent of the area exclusively covered by sensilla placoidea on the antennal flagellum of the male. A lectotype is designated for C. chloromelas. A Chilean Patagonian population of C. moscosensis n. sp. was observed to dig spatially clumped nests in an earth bank with a moderately hard and humid soil. The presence of multiple females within single nest tunnels is unusual and may preliminary suggest nest-sharing, but more data are necessary to define the social organization of this species. The species appears to be polylectic. Bee nests were attacked by satellite flies and possibly velvet ants.

Electrochemical cell design

DOEpatents

Arntzen, John D.

1978-01-01

An electrochemical cell includes two outer electrodes and a central electrode of opposite polarity, all nested within a housing having two symmetrical halves which together form an offset configuration. The outer electrodes are nested within raised portions within the side walls of each housing half while the central electrode sealingly engages the perimetric margins of the side-wall internal surfaces. Suitable interelectrode separators and electrical insulating material electrically isolate the central electrode from the housing and the outer electrodes. The outer electrodes are electrically connected to the internal surfaces of the cell housing to provide current collection. The nested structure minimizes void volume that would otherwise be filled with gas or heavy electrolyte and also provides perimetric edge surfaces for sealing and supporting at the outer margins of frangible interelectrode separator layers.

Isolating causal pathways between flow and fish in the regulated river hierarchy

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

McManamay, Ryan A.; Peoples, Brandon K.; Orth, Donald J.

Unregulated river systems are organized in a hierarchy in which large-scale factors (i.e., landscape and segment scales) influence local habitats (i.e., reach, meso-, and microhabitat scales), and both differentially exert selective pressures on biota. Dams, however, create discontinua in these processes and change the hierarchical structure. We examined the relative roles of hydrology and other instream factors, within a hierarchical landscape context, in organizing fish communities in regulated and unregulated tributaries to the Upper Tennessee River, USA. We also used multivariate regression trees to identify factors that partition fish assemblages based on trait similarities, irrespective of spatial scale. Then, wemore » used classical path analysis and structural equation modeling to evaluate the most plausible hierarchical causal structure of specific trait-based community components, given the data. Both statistical approaches suggested that river regulation affects stream fishes through a variety of reach-scale variables, not always through hydrology itself. Though we observed different changes in flow, temperature, and biotic responses according to regulation types, the most predominant path in which dam regulation affected biota was via temperature alterations. Diversion dams had the strongest effects on fish assemblages. Diversion dams reduced flow magnitudes, leading to declines in fish richness but increased temperatures, leading to lower abundances in equilibrium species and nest guarders. Peaking and run-of-river dams increased flow variability, leading to lower abundances in nest-guarding fishes. Flow displayed direct relationships with biotic responses; however, results indicated that changes in temperature and substrate had equal, if not stronger, effects on fish assemblage composition. The strength and nature of relationships depended on whether flow metrics were standardized for river size. Here, we suggest that restoration efforts in regulated rivers focus on improving flow conditions in conjunction with temperature and substrate restoration.« less

Isolating causal pathways between flow and fish in the regulated river hierarchy

DOE PAGES

McManamay, Ryan A.; Peoples, Brandon K.; Orth, Donald J.; ...

2015-07-07

Unregulated river systems are organized in a hierarchy in which large-scale factors (i.e., landscape and segment scales) influence local habitats (i.e., reach, meso-, and microhabitat scales), and both differentially exert selective pressures on biota. Dams, however, create discontinua in these processes and change the hierarchical structure. We examined the relative roles of hydrology and other instream factors, within a hierarchical landscape context, in organizing fish communities in regulated and unregulated tributaries to the Upper Tennessee River, USA. We also used multivariate regression trees to identify factors that partition fish assemblages based on trait similarities, irrespective of spatial scale. Then, wemore » used classical path analysis and structural equation modeling to evaluate the most plausible hierarchical causal structure of specific trait-based community components, given the data. Both statistical approaches suggested that river regulation affects stream fishes through a variety of reach-scale variables, not always through hydrology itself. Though we observed different changes in flow, temperature, and biotic responses according to regulation types, the most predominant path in which dam regulation affected biota was via temperature alterations. Diversion dams had the strongest effects on fish assemblages. Diversion dams reduced flow magnitudes, leading to declines in fish richness but increased temperatures, leading to lower abundances in equilibrium species and nest guarders. Peaking and run-of-river dams increased flow variability, leading to lower abundances in nest-guarding fishes. Flow displayed direct relationships with biotic responses; however, results indicated that changes in temperature and substrate had equal, if not stronger, effects on fish assemblage composition. The strength and nature of relationships depended on whether flow metrics were standardized for river size. Here, we suggest that restoration efforts in regulated rivers focus on improving flow conditions in conjunction with temperature and substrate restoration.« less

Double-layer interlaced nested multi-ring array metallic mesh for high-performance transparent electromagnetic interference shielding.

PubMed

Wang, Heyan; Lu, Zhengang; Liu, Yeshu; Tan, Jiubin; Ma, Limin; Lin, Shen

2017-04-15

We report a nested multi-ring array metallic mesh (NMA-MM) that shows a highly uniform diffraction pattern theoretically and experimentally. Then a high-performance transparent electromagnetic interference (EMI) shielding structure is constituted by the double-layer interlaced NMA-MMs separated by transparent quartz-glass substrate. Experimental results show that double-layer interlaced NMA-MM structure exhibits a shielding effectiveness (SE) of over 27 dB in the Ku-band, with a maximal SE of 37 dB at 12 GHz, normalized optical transmittance of 90%, and minimal image quality degradation due to the interlaced arrangement. It thus shows great potential for practical applications in transparent EMI shielding devices.

Fluctuations in a metapopulation of nesting four-toed salamanders, Hemidactylium scutatum, in the Great Smoky Mountains National Park, USA, 1999-2003

USGS Publications Warehouse

Corser, J.D.; Dodd, C.K.

2004-01-01

We tested two predictions associated with the hypothesis that certain populations of pond-breeding amphibians are structured into metapopulations using minimum relative abundance estimates of nesting four-toed salamanders (Hemidactylium scutatum Schlegel) from 11 different ponds in the Great Smoky Mountains National Park. Coefficients of variation (CV) for counts at individual ponds ranged from 0.25 to 1.26, and the overall mean CV at all 11 ponds was 0.34. Many pairs of ponds had negative correlations in abundance from 1999-2003, whereas others had various degrees of positive correlation (mean r = 0.29). Thus, nesting population size fluctuated semi-independently among the ponds from year to year, inferring the existence of inter-pond dispersal. The mean number of nesting females at a pond was negatively, but non-significantly, correlated (r = -0.27; P = 0.40; 10 d.f.) to the pond's isolation. Owing to physiological constraints on plethodontid salamander energetics, precipitation during the nesting season (February and March) appeared to play an important role (r = 0.78; P = 0.12; 4 d.f.) in the number of nesting females we observed. Unlike some other plethodontid salamander populations in more fragmented southern Appalachian forest ecosystems, this (meta)population within Great Smoky Mountains National Park does not appear to be declining.

North American osprey populations and contaminants: Historic and contemporary perspectives

USGS Publications Warehouse

Henny, Charles J.; Grove, Robert A.; Kaiser, James L.; Johnson, Branden L.

2010-01-01

Osprey (Pandion haliaetus) populations were adversely affected by DDT and perhaps other contaminants in the United States and elsewhere. Reduced productivity, eggshell thinning, and high DDE concentrations in eggs were the signs associated with declining osprey populations in the 1950s, 1960s, and 1970s. The species was one of the first studied on a large scale to bring contaminant issues into focus. Although few quantitative population data were available prior to the 1960s, many osprey populations in North America were studied during the 1960s and 1970s with much learned about basic life history and biology. This article reviews the historical and current effects of contaminants on regional osprey populations. Breeding populations in many regions of North America showed post-DDT-era (1972) population increases of varying magnitudes, with many populations now appearing to stabilize at much higher numbers than initially reported in the 1970s and 1980s. However, the magnitude of regional population increases in the United States between 1981 (first Nationwide Survey, ∼8,000 pairs), when some recovery had already occurred, 1994 (second survey, ∼14,200), and 2001 (third survey, ∼16,000–19,000), or any other years, is likely not a simple response to the release from earlier contaminant effects, but a response to multi-factorial effects. This indirect “contaminant effects” measurement comparing changes (i.e., recovery) in post-DDT-era population numbers over time is probably confounded by changing human attitudes toward birds of prey (shooting, destroying nests, etc.), changing habitats, changing fish populations, and perhaps competition from other species. The species' adaptation to newly created reservoirs and its increasing use of artificial nesting structures (power poles, nesting platforms, cell towers, channel markers, offshore duck blinds, etc.) are two important factors. The timing of the initial use of artificial nesting structures, which replaced declining numbers of suitable trees at many locations, varied regionally (much later in the western United States and Mexico). Because of the increasing use of artificial nesting structures, there may be more ospreys nesting in North America now than ever before. Now, with the impact of most legacy organic contaminants (DDT, other organochlorine [OC] pesticides, polychlorinated biphenyls [PCB], polychlorinated dibenzo-p-dioxins [PCDD], polychlorinated dibenzofurans (PCDF]) greatly reduced or eliminated, and some osprey populations showing evidence of stabilizing, the species was proposed as a Worldwide Sentinel Species for evaluating emerging contaminants. Several emerging contaminants are already being studied, such as polybrominated diphenyl ethers (PBDE) and perfluorinated acids and sulfonate compounds (PFC). The many advantages for continued contaminant investigations using the osprey include a good understanding of its biology and ecology, its known distribution and abundance, and its ability to habituate to humans and their activities, which permits nesting in some of the potentially most contaminated environments. It is a top predator in most ecosystems, and its nests are relatively easy to locate and study with little researcher impact on reproductive success.

Considering Spatial Scale and Reproductive Consequences of Habitat Selection when Managing Grasslands for a Threatened Species

PubMed Central

Pearson, Scott F.; Knapp, Shannon M.

2016-01-01

Habitat selection that has fitness consequences has important implications for conservation activities. For example, habitat characteristics that influence nest success in birds can be manipulated to improve habitat quality with the goal of ultimately improving reproductive success. We examined habitat selection by the threatened streaked horned lark (Eremophila alpestris strigata) at both the breeding-site (territory) and nest-site scales. Larks were selective at both spatial scales but with contrasting selection. At the territory scale, male larks selected sparsely vegetated grasslands with relatively short vegetation. At the nest-site scale, female larks selected sites within territories with higher vegetation density and more perennial forbs. These nest-site scale choices had reproductive consequences, with greater nest success in areas with higher densities of perennial forbs. We experimentally manipulated lark habitat structure in an attempt to mimic the habitat conditions selected by larks by using late summer prescribed fires. After the burn, changes in vegetation structure were in the direction preferred by larks but habitat effects attenuated by the following year. Our results highlight the importance of evaluating habitat selection at spatial scales appropriate to the species of interest, especially when attempting to improve habitat quality for rare and declining species. They also highlight the importance of conducting restoration activities in a research context. For example, because the sparsely vegetated conditions created by fire attenuate, there may be value in examining more frequent burns or hotter fires as the next management and research action. We hope the design outlined in this study will serve as an integrated research and management example for conserving grassland birds generally. PMID:27322196

Molecular microelectrostatic view on electronic states near pentacene grain boundaries

NASA Astrophysics Data System (ADS)

Verlaak, Stijn; Heremans, Paul

2007-03-01

Grain boundaries are the most inevitable and pronounced structural defects in pentacene films. To study the effect of those structural defects on the electronic state distribution, the energy levels of a hole on molecules at and near the defect have been calculated using a submolecular self-consistent-polarization-field approach in combination with atomic charge-quadrupole interaction energy calculations. This method has been benchmarked prior to application on four idealized grain boundaries: a grain boundary void, a void with molecules squeezed in between two grains, a boundary between two grains with different crystallographic orientations, and a grain boundary void in which a permanent dipole (e.g., a water molecule) has nested. While idealized, those views highlight different aspects of real grain boundaries. Implications on macroscopic charge transport models are discussed, as well as some relation between growth conditions and the formation of the grain boundary.

Nest-site competition between invasive and native cavity nesting birds and its implication for conservation.

PubMed

Charter, Motti; Izhaki, Ido; Ben Mocha, Yitzchak; Kark, Salit

2016-10-01

Nesting cavities are often a limited resource that multiple species use. There is an ongoing discussion on whether invasive cavity nesting birds restrict the availability of this key limited resource. While the answer to this question has important conservation implications, little experimental work has been done to examine it. Here, we aimed to experimentally test whether alien cavity nesting birds affect the occupancy of cavities and the resulting breeding success of native cavity breeders in a large urban park located in Tel Aviv, Israel. Over three breeding seasons, we manipulated the entry size of nest boxes and compared the occupancy and breeding success of birds in nest boxes of two treatments. These included nest boxes with large-entrance and small-entrance holes. The large-entrance holes allowed access for both the native and invasive birds (the two main aliens in the park are the common mynas and rose-ringed parakeets). The smaller-entrance boxes, on the other hand, allowed only the smaller sized native cavity breeders (great tits and house sparrows) to enter the boxes but prevented the alien species from entering. We found that the large-entrance nest boxes were occupied by five different bird species, comprising three natives (great tit, house sparrow, Scops owl) and two invasive species (common myna, rose-ringed parakeet) while the small-entrance boxes were only occupied by the two native species. The alien common mynas and rose-ringed parakeets occupied 77.5% of the large-entrance nest boxes whereas native species, mainly great tits, occupied less than 9% of the large-entrance boxes and 36.5% of the small-entrance boxes. When examining the occupancy of those cavities that were not occupied by the aliens, natives occupied both the small and large-entrance nest boxes equally. Three quarters (78%) of the great tits breeding in the large-entrance boxes were usurped by common mynas during the breeding season and as a result breeding success was significantly lower for great tits breeding in the large-entrance boxes compared with the small-entrance boxes. The results of this study suggests that the invasive alien species can reduce the breeding potential of native cavity breeders both by exploiting the limited breeding resource (nest cavities) and by directly usurping cavities already occupied by the native species. Since the majority of large-entrance nest boxes were occupied by the larger alien birds, less native species bred in the limited number of unoccupied large-entrance nest boxes because of exploitation competition. We propose that for management purposes, nest-box programs that alter the entrance size of available natural cavities may be a practical approach, reducing the competition between native cavity breeders and alien invasive birds, and especially benefiting the smaller native cavity breeders. Copyright © 2016 Elsevier Ltd. All rights reserved.

A multiplex nested PCR for the detection and identification of Candida species in blood samples of critically ill paediatric patients

PubMed Central

2014-01-01

Background Nosocomial candidaemia is associated with high mortality rates in critically ill paediatric patients; thus, the early detection and identification of the infectious agent is crucial for successful medical intervention. The PCR-based techniques have significantly increased the detection of Candida species in bloodstream infections. In this study, a multiplex nested PCR approach was developed for candidaemia detection in neonatal and paediatric intensive care patients. Methods DNA samples from the blood of 54 neonates and children hospitalised in intensive care units with suspected candidaemia were evaluated by multiplex nested PCR with specific primers designed to identify seven Candida species, and the results were compared with those obtained from blood cultures. Results The multiplex nested PCR had a detection limit of four Candida genomes/mL of blood for all Candida species. Blood cultures were positive in 14.8% of patients, whereas the multiplex nested PCR was positive in 24.0% of patients, including all culture-positive patients. The results obtained with the molecular technique were available within 24 hours, and the assay was able to identify Candida species with 100% of concordance with blood cultures. Additionally, the multiplex nested PCR detected dual candidaemia in three patients. Conclusions Our proposed PCR method may represent an effective tool for the detection and identification of Candida species in the context of candidaemia diagnosis in children, showing highly sensitive detection and the ability to identify the major species involved in this infection. PMID:25047415

A multiplex nested PCR for the detection and identification of Candida species in blood samples of critically ill paediatric patients.

PubMed

Taira, Cleison Ledesma; Okay, Thelma Suely; Delgado, Artur Figueiredo; Ceccon, Maria Esther Jurfest Rivero; de Almeida, Margarete Teresa Gottardo; Del Negro, Gilda Maria Barbaro

2014-07-21

Nosocomial candidaemia is associated with high mortality rates in critically ill paediatric patients; thus, the early detection and identification of the infectious agent is crucial for successful medical intervention. The PCR-based techniques have significantly increased the detection of Candida species in bloodstream infections. In this study, a multiplex nested PCR approach was developed for candidaemia detection in neonatal and paediatric intensive care patients. DNA samples from the blood of 54 neonates and children hospitalised in intensive care units with suspected candidaemia were evaluated by multiplex nested PCR with specific primers designed to identify seven Candida species, and the results were compared with those obtained from blood cultures. The multiplex nested PCR had a detection limit of four Candida genomes/mL of blood for all Candida species. Blood cultures were positive in 14.8% of patients, whereas the multiplex nested PCR was positive in 24.0% of patients, including all culture-positive patients. The results obtained with the molecular technique were available within 24 hours, and the assay was able to identify Candida species with 100% of concordance with blood cultures. Additionally, the multiplex nested PCR detected dual candidaemia in three patients. Our proposed PCR method may represent an effective tool for the detection and identification of Candida species in the context of candidaemia diagnosis in children, showing highly sensitive detection and the ability to identify the major species involved in this infection.

Inter-nesting habitat-use patterns of loggerhead sea turtles: Enhancing satellite tracking with benthic mapping

USGS Publications Warehouse

Hart, Kristen M.; Zawada, David G.; Fujisaki, Ikuko; Lidz, Barbara H.

2010-01-01

The loggerhead sea turtle Caretta caretta faces declining nest numbers and bycatches from commercial longline fishing in the southeastern USA. Understanding spatial and temporal habitat-use patterns of these turtles, especially reproductive females in the neritic zone, is critical for guiding management decisions. To assess marine turtle habitat use within the Dry Tortugas National Park (DRTO), we used satellite telemetry to identify core-use areas for 7 loggerhead females inter-nesting and tracked in 2008 and 2009. This effort represents the first tracking of DRTO loggerheads, a distinct subpopulation that is 1 of 7 recently proposed for upgrading from threatened to endangered under the US Endangered Species Act. We also used a rapid, high-resolution, digital imaging system to map benthic habitats in turtle core-use areas (i.e. 50% kernel density zones). Loggerhead females were seasonal residents of DRTO for 19 to 51 d, and individual inter-nesting habitats were located within 1.9 km (2008) and 2.3 km (2009) of the nesting beach and tagging site. The core area common to all tagged turtles was 4.2 km2 in size and spanned a depth range of 7.6 to 11.5 m. Mapping results revealed the diversity and distributions of benthic cover available in the core-use area, as well as a heavily used corridor to/from the nesting beach. This combined tagging-mapping approach shows potential for planning and improving the effectiveness of marine protected areas and for developing spatially explicit conservation plans.

Experimental demonstration of the fitness consequences of an introduced parasite of Darwin's finches.

PubMed

Koop, Jennifer A H; Huber, Sarah K; Laverty, Sean M; Clayton, Dale H

2011-05-11

Introduced parasites are a particular threat to small populations of hosts living on islands because extinction can occur before hosts have a chance to evolve effective defenses. An experimental approach in which parasite abundance is manipulated in the field can be the most informative means of assessing a parasite's impact on the host. The parasitic fly Philornis downsi, recently introduced to the Galápagos Islands, feeds on nestling Darwin's finches and other land birds. Several correlational studies, and one experimental study of mixed species over several years, reported that the flies reduce host fitness. Here we report the results of a larger scale experimental study of a single species at a single site over a single breeding season. We manipulated the abundance of flies in the nests of medium ground finches (Geospiza fortis) and quantified the impact of the parasites on nestling growth and fledging success. We used nylon nest liners to reduce the number of parasites in 24 nests, leaving another 24 nests as controls. A significant reduction in mean parasite abundance led to a significant increase in the number of nests that successfully fledged young. Nestlings in parasite-reduced nests also tended to be larger prior to fledging. Our results confirm that P. downsi has significant negative effects on the fitness of medium ground finches, and they may pose a serious threat to other species of Darwin's finches. These data can help in the design of management plans for controlling P. downsi in Darwin's finch breeding populations.

The Rocky Mountain population of the western Canada goose: its distribution, habitats, and management

USGS Publications Warehouse

Krohn, William B.; Bizeau, Elwood G.

1980-01-01

The western Canada goose (Branta canadensis moffitti) was divided into a Rocky Mountain population (RMP) and a Pacific population (PP) on the basis of band recovery patterns examined in this study and recovery data from other investigators. Habitat information obtained from nine cooperating wildlife agencies within the RMP's range provided a base line for evaluating future changes in nesting, molting, and wintering areas. The habitat inventory indicated that none of the seasonal habitats were currently limiting the size of the RMP. The RMP's range is divided into 15 reference areas and these are briefly described. Past studies of Canada geese in the Intermountain Region are reviewed. Topics covered in the discussion of breeding biology are nesting chronology, spring population composition, breeding age, clutch size, nesting success. artificial nesting structures, and gosling survival. Much of the mortality of Canada geese occurs before the birds are fledged. Man-made nesting structures reduce losses during incubation. but research is needed on the relations between brooding sites and gosling survival. Some western Canada geese, mainly prebreeders and unsuccessful nesters, make molt migrations to and from molting areas during and after the brood-rearing season. More than half of these molt-migrants are yearlings too young to nest; there are indications that even some successful nesters leave nesting areas to molt before the fledging of their offspring. Geese 2 years old or older may serve as guides to traditional molting areas for the first-time migrants (i.e., yearlings). Lack of disturbance appears to influence selection of specific molting areas within the nesting range of moffitti, whereas movements of molters out of the Intermountain Region may be related to the evolution of this subspecies. Apparently. molters of both the PP and RMP that leave the Region go to the Northwest Territories of Canada. Although the taxonomic status of moffitti as related to the giant Canada goose (B. c. maxima) is unclear. these two subspecies are closely related. as evidenced by similar molt migrations to subarctic Canada. similar blood serum proteins. and only dinal differences in body size ,!!nd color. Mean annual survival rates for birds banded on nesting areas averaged 53 ? 2% (X ? SE) for immatures and 64 ? 1 % for adults. Mean annual survival rates of adults captured on molting areas averaged 70 ? 1 %. Sport hunting accounts for more than 86% of the mortality of fledged Rocky Mountain geese. and hunting may limit the population's growth. Because the number of waterfowl hunters in the Rocky Mountain West is increasing, the continued expansion or future maintenance of the RMP may require more restrictive hunting regulations. Other management recommendations include the refinement and standardization of spring and winter aerial surveys, and more accurate age and sex determinations when geese are banded and color-marked.

Novel approach based on one-tube nested PCR and a lateral flow strip for highly sensitive diagnosis of tuberculous meningitis.

PubMed

Sun, Yajuan; Chen, Jiajun; Li, Jia; Xu, Yawei; Jin, Hui; Xu, Na; Yin, Rui; Hu, Guohua

2017-01-01

Rapid and sensitive detection of Mycobacterium tuberculosis (M. Tb) in cerebrospinal fluid is crucial in the diagnosis of tuberculous meningitis (TBM), but conventional diagnostic technologies have limited sensitivity and specificity or are time-consuming. In this work, a novel, highly sensitive molecular diagnostic method, one-tube nested PCR-lateral flow strip test (OTNPCR-LFST), was developed for detecting M. tuberculosis. This one-tube nested PCR maintains the sensitivity of conventional two-step nested PCR and reduces both the chance of cross-contamination and the time required for analysis. The PCR product was detected by a lateral flow strip assay, which provided a basis for migration of the test to a point-of-care (POC) microfluidic format. The developed assay had an improved sensitivity compared with traditional PCR, and the limit of detection was up to 1 fg DNA isolated from M. tuberculosis. The assay was also specific for M. tuberculosis, and no cross-reactions were found in other non-target bacteria. The application of this technique to clinical samples was successfully evaluated, and OTNPCR-LFST showed 89% overall sensitivity and 100% specificity for TBM patients. This one-tube nested PCR-lateral flow strip assay is useful for detecting M. tuberculosis in TBM due to its rapidity, high sensitivity and simple manipulation.

Protecting unknown two-qubit entangled states by nesting Uhrig's dynamical decoupling sequences

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

Mukhtar, Musawwadah; Soh, Wee Tee; Saw, Thuan Beng

2010-11-15

Future quantum technologies rely heavily on good protection of quantum entanglement against environment-induced decoherence. A recent study showed that an extension of Uhrig's dynamical decoupling (UDD) sequence can (in theory) lock an arbitrary but known two-qubit entangled state to the Nth order using a sequence of N control pulses [Mukhtar et al., Phys. Rev. A 81, 012331 (2010)]. By nesting three layers of explicitly constructed UDD sequences, here we first consider the protection of unknown two-qubit states as superposition of two known basis states, without making assumptions of the system-environment coupling. It is found that the obtained decoherence suppression canmore » be highly sensitive to the ordering of the three UDD layers and can be remarkably effective with the correct ordering. The detailed theoretical results are useful for general understanding of the nature of controlled quantum dynamics under nested UDD. As an extension of our three-layer UDD, it is finally pointed out that a completely unknown two-qubit state can be protected by nesting four layers of UDD sequences. This work indicates that when UDD is applicable (e.g., when the environment has a sharp frequency cutoff and when control pulses can be taken as instantaneous pulses), dynamical decoupling using nested UDD sequences is a powerful approach for entanglement protection.« less

[Approach to the Development of Mind and Persona].

PubMed

Sawaguchi, Toshiko

2018-01-01

To access medical specialists by health specialists working in the regional health field, the possibility of utilizing the voice approach for dissociative identity disorder (DID) patients as a health assessment for medical access (HAMA) was investigated. The first step is to investigate whether the plural personae in a single DID patient can be discriminated by voice analysis. Voices of DID patients including these with different personae were extracted from YouTube and were analysed using the software PRAAT with basic frequency, oral factors, chin factors and tongue factors. In addition, RAKUGO story teller voices made artificially and dramatically were analysed in the same manner. Quantitive and qualitative analysis method were carried out and nested logistic regression and a nested generalized linear model was developed. The voice from different personae in one DID patient could be visually and easily distinquished using basic frequency curve, cluster analysis and factor analysis. In the canonical analysis, only Roy's maximum root was <0.01. In the nested generalized linear model, the model using a standard deviation (SD) indicator fit best and some other possibilities are shown here. In DID patients, the short transition time among plural personae could guide to the risky situation such as suicide. So if the voice approach can show the time threshold of changes between the different personae, it would be useful as an Access Assessment in the form of a simple HAMA.

Disease in the Society: Infectious Cadavers Result in Collapse of Ant Sub-Colonies.

PubMed

Loreto, Raquel G; Hughes, David P

2016-01-01

Despite the growing number of experimental studies on mechanisms of social immunity in ant societies, little is known about how social behavior relates to disease progression within the nests of ants. In fact, when empirically studying disease in ant societies, it is common to remove dead ants from experiments to confirm infection by the studied parasite. This unfortunately does not allow disease to progress within the nest as it may be assumed would happen under natural conditions. Therefore, the approach taken so far has resulted in a limited knowledge of diseases dynamics within the nest environment. Here we introduced a single infectious cadaver killed by the fungus Beauveria bassiana into small nests of the ant Camponotus castaneus. We then observed the natural progression of the disease by not removing the corpses of the ants that died following the first entry of the disease. Because some behaviors such as social isolation of sick individuals or the removal of cadavers by nestmates are considered social immune functions and thus adaptations at the colony level that reduce disease spread, we also experimentally confined some sub-colonies to one or two chamber nests to prevent the expression of such behaviors. Based on 51 small nests and survival studies in 1,003 ants we found that a single introduced infectious cadaver was able to transmit within the nest, and social immunity did not prevent the collapse of the small sub-colonies here tested. This was true whether ants did or did not have the option to remove the infectious cadaver. Therefore, we found no evidence that the typically studied social immunity behaviors can reduce disease spread in the conditions here tested.