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Sample records for future prey behavior

  1. Ecoepidemic predator-prey model with feeding satiation, prey herd behavior and abandoned infected prey.

    PubMed

    Kooi, Bob W; Venturino, Ezio

    2016-04-01

    In this paper we analyse a predator-prey model where the prey population shows group defense and the prey individuals are affected by a transmissible disease. The resulting model is of the Rosenzweig-MacArthur predator-prey type with an SI (susceptible-infected) disease in the prey. Modeling prey group defense leads to a square root dependence in the Holling type II functional for the predator-prey interaction term. The system dynamics is investigated using simulations, classical existence and asymptotic stability analysis and numerical bifurcation analysis. A number of bifurcations, such as transcritical and Hopf bifurcations which occur commonly in predator-prey systems will be found. Because of the square root interaction term there is non-uniqueness of the solution and a singularity where the prey population goes extinct in a finite time. This results in a collapse initiated by extinction of the healthy or susceptible prey and thereafter the other population(s). When also a positive attractor exists this leads to bistability similar to what is found in predator-prey models with a strong Allee effect. For the two-dimensional disease-free (i.e. the purely demographic) system the region in the parameter space where bistability occurs is marked by a global bifurcation. At this bifurcation a heteroclinic connection exists between saddle prey-only equilibrium points where a stable limit cycle together with its basin of attraction, are destructed. In a companion paper (Gimmelli et al., 2015) the same model was formulated and analysed in which the disease was not in the prey but in the predator. There we also observed this phenomenon. Here we extend its analysis using a phase portrait analysis. For the three-dimensional ecoepidemic predator-prey system where the prey is affected by the disease, also tangent bifurcations including a cusp bifurcation and a torus bifurcation of limit cycles occur. This leads to new complex dynamics. Continuation by varying one parameter

  2. Prey Capture Behavior in an Arboreal African Ponerine Ant

    PubMed Central

    Dejean, Alain

    2011-01-01

    I studied the predatory behavior of Platythyrea conradti, an arboreal ponerine ant, whereas most species in this subfamily are ground-dwelling. The workers, which hunt solitarily only around dusk, are able to capture a wide range of prey, including termites and agile, nocturnal insects as well as diurnal insects that are inactive at that moment of the Nyctemeron, resting on tree branches or under leaves. Prey are captured very rapidly, and the antennal palpation used by ground-dwelling ponerine species is reduced to a simple contact; stinging occurs immediately thereafter. The venom has an instant, violent effect as even large prey (up to 30 times the weight of a worker) never struggled after being stung. Only small prey are not stung. Workers retrieve their prey, even large items, singly. To capture termite workers and soldiers defending their nest entrances, ant workers crouch and fold their antennae backward. In their role as guards, the termites face the crouching ants and end up by rolling onto their backs, their legs batting the air. This is likely due to volatile secretions produced by the ants' mandibular gland. The same behavior is used against competing ants, including territorially-dominant arboreal species that retreat further and further away, so that the P. conradti finally drive them from large, sugary food sources. PMID:21589941

  3. Prey capture behavior in an arboreal African ponerine ant.

    PubMed

    Dejean, Alain

    2011-01-01

    I studied the predatory behavior of Platythyrea conradti, an arboreal ponerine ant, whereas most species in this subfamily are ground-dwelling. The workers, which hunt solitarily only around dusk, are able to capture a wide range of prey, including termites and agile, nocturnal insects as well as diurnal insects that are inactive at that moment of the Nyctemeron, resting on tree branches or under leaves. Prey are captured very rapidly, and the antennal palpation used by ground-dwelling ponerine species is reduced to a simple contact; stinging occurs immediately thereafter. The venom has an instant, violent effect as even large prey (up to 30 times the weight of a worker) never struggled after being stung. Only small prey are not stung. Workers retrieve their prey, even large items, singly. To capture termite workers and soldiers defending their nest entrances, ant workers crouch and fold their antennae backward. In their role as guards, the termites face the crouching ants and end up by rolling onto their backs, their legs batting the air. This is likely due to volatile secretions produced by the ants' mandibular gland. The same behavior is used against competing ants, including territorially-dominant arboreal species that retreat further and further away, so that the P. conradti finally drive them from large, sugary food sources. PMID:21589941

  4. Mechanical work as a determinant of prey-handling behavior in the tokay gecko (Gekko gecko).

    PubMed

    Andrews, C; Bertram, J E

    1997-01-01

    In this study an in vitro analysis of the force and mechanical work required to bite prey items of different size and physical character is combined with an in vivo analysis of prey-handling behavior in the tokay gecko (Gekko gecko). The force required to bite and the work of biting increase with prey size, but the rate of increase is prey specific, with crickets (Acheta domestica) requiring substantially more force and work per bite than larvae (Galleria mellonella and Manduca sexta) for all but the smallest prey. Prey-handling behavior is also prey specific. Geckos exert more bites per feeding event on small crickets than on small insect larvae, but the number of bites increases faster with prey mass for larvae than for crickets. Combination of the in vitro mechanical measurements with the in vivo behavior analysis allows the calculation of total mechanical work per feeding event and indicates that total work increases with prey size but that the difference between prey types is far less than predicted from the differences in structural properties of the prey. This occurs because the number of bites and work per bite relationships tend to cancel the differences in the total work necessary to process each prey type. Thus, when considering the effect of prey size, a 13-fold greater rate of increase in bite force and an 18-fold greater rate of increase of work per bit for crickets over larvae was partially compensated for by a threefold increase in the number of bites used on larvae relative to crickets. These results can be interpreted in two ways. The effect of mechanical work in feeding behavior suggests that the energetics of jaw adductor musculature could play a greater role in governing the feeding behavior of this lizard than has previously been expected. Alternatively, the scaling of work in feeding over a range of prey sizes suggests distinct differences in the geometric features of the prey that determine how they are processed. PMID:9231392

  5. Critical behavior of a lattice prey-predator model

    NASA Astrophysics Data System (ADS)

    Antal, Tibor; Droz, Michel; Lipowski, Adam; Ódor, Géza

    2001-09-01

    The critical properties of a simple prey-predator model are revisited. For some values of the control parameters, the model exhibits a line of directed percolationlike transitions to a single absorbing state. For other values of the control parameters one finds a second line of continuous transitions toward an infinite number of absorbing states, and the corresponding steady-state exponents are mean-field-like. The critical behavior of the special point T (bicritical point), where the two transition lines meet, belongs to a different universality class. A particular strategy for preparing the initial states used for the dynamical Monte Carlo method is devised to correctly describe the physics of the system near the second transition line. Relationships with a forest fire model with immunization are also discussed.

  6. Foraging Behavior in Guppies: Do Size and Color of Prey Make a Difference?

    ERIC Educational Resources Information Center

    Rop, Charles J.

    2001-01-01

    Describes an animal behavior experiment using guppies. Students observe the behavior of a guppy as it feeds on prey and make observations, collect and analyze data, draw conclusions, and design their own experiments. (SAH)

  7. Collective behavior and predation success in a predator-prey model inspired by hunting bats

    NASA Astrophysics Data System (ADS)

    Lin, Yuan; Abaid, Nicole

    2013-12-01

    We establish an agent-based model to study the impact of prey behavior on the hunting success of predators. The predators and prey are modeled as self-propelled particles moving in a three-dimensional domain and subject to specific sensing abilities and behavioral rules inspired by bat hunting. The predators randomly search for prey. The prey either align velocity directions with peers, defined as "interacting" prey, or swarm "independently" of peer presence; both types of prey are subject to additive noise. In a simulation study, we find that interacting prey using low noise have the maximum predation avoidance because they form localized large groups, while they suffer high predation as noise increases due to the formation of broadly dispersed small groups. Independent prey, which are likely to be uniformly distributed in the domain, have higher predation risk under a low noise regime as they traverse larger spatial extents. These effects are enhanced in large prey populations, which exhibit more ordered collective behavior or more uniform spatial distribution as they are interacting or independent, respectively.

  8. BEHAVIOR AND PREY OF NESTING RED-SHOULDERED HAWKS IN SOUTHWESTERN OHIO

    EPA Science Inventory

    We used direct observations to quantify prey types, prey delivery rate, and adult and nestling behavior at nests of Red-shouldered Hawks (Buteo lineatus) in suburban southwestern Ohio. Twenty-one nests were observed for a total of 256 hr in 1997-2001. Small mammals made up the ...

  9. Inferring Predator Behavior from Attack Rates on Prey-Replicas That Differ in Conspicuousness

    PubMed Central

    2012-01-01

    Behavioral ecologists and evolutionary biologists have long studied how predators respond to prey items novel in color and pattern. Because a predatory response is influenced by both the predator’s ability to detect the prey and a post-detection behavioral response, variation among prey types in conspicuousness may confound inference about post-prey-detection predator behavior. That is, a relatively high attack rate on a given prey type may result primarily from enhanced conspicuousness and not predators’ direct preference for that prey. Few studies, however, account for such variation in conspicuousness. In a field experiment, we measured predation rates on clay replicas of two aposematic forms of the poison dart frog Dendrobates pumilio, one novel and one familiar, and two cryptic controls. To ask whether predators prefer or avoid a novel aposematic prey form independently of conspicuousness differences among replicas, we first modeled the visual system of a typical avian predator. Then, we used this model to estimate replica contrast against a leaf litter background to test whether variation in contrast alone could explain variation in predator attack rate. We found that absolute predation rates did not differ among color forms. Predation rates relative to conspicuousness did, however, deviate significantly from expectation, suggesting that predators do make post-detection decisions to avoid or attack a given prey type. The direction of this deviation from expectation, though, depended on assumptions we made about how avian predators discriminate objects from the visual background. Our results show that it is important to account for prey conspicuousness when investigating predator behavior and also that existing models of predator visual systems need to be refined. PMID:23119039

  10. Naïve prey exhibit reduced antipredator behavior and survivorship

    PubMed Central

    2014-01-01

    Prey naiveté has been hypothesized to be one of the major driving forces behind population declines following the introduction of novel predators or release of inexperienced prey into predator rich environments. In these cases, naïve prey may lack sufficient antipredator behavior and, as a result, suffer increased mortality. Despite this, some evidence suggests that many prey utilize a generalized response to predators. Here, the naiveté hypothesis is tested using a predator–prey pair sharing an evolutionary history: the red swamp crayfish (Procambarus clarkii Girard, 1852) and largemouth bass (Micropterus salmoides Lacépède, 1802). Using farm-reared, naïve crayfish and wild-caught, experienced individuals, laboratory experiments demonstrated that naïve, farmed crayfish lack behavioral responses to chemical cues from bass, both in terms of movement and use of structural refuge. In contrast, experienced crayfish responded strongly to the same cues. In a subsequent field tethering experiment, these naïve individuals suffered a three-fold increase in predation rate. Based on these results, recognition of predators may not be innate in all prey, and previous experience and learning likely play a key role in the development of antipredator behavior. PMID:25392763

  11. Prey processing in amniotes: biomechanical and behavioral patterns of food reduction.

    PubMed

    Reilly, S M; McBrayer, L D; White, T D

    2001-03-01

    In this paper we examine the biomechanics of prey processing behavior in the amniotes. Whether amniotes swallow prey items whole or swallow highly processed slurries or boluses of food, they share a common biomechanical system where hard surfaces (teeth or beaks) are brought together on articulated jaws by the actions of adductor muscles to grasp and process food. How have amniotes modified this basic system to increase the chewing efficiency of the system? To address this question we first examine the primitive condition for prey processing representative of many of the past and present predatory amniotes. Because herbivory is expected to be related to improved prey processing in the jaws we review patterns of food processing mechanics in past and present herbivores. Herbivory has appeared numerous times in amniotes and several solutions to the task of chewing plant matter have appeared. Birds have abandoned jaw chewing in favor of a new way to chew--with the gut--so we will detour from the jaws to examine the appearance of gut chewing in the archosaurs. We will then fill in the gaps among amniote taxa with a look at some new data on patterns of prey processing behavior and jaw mechanics in lizards. Finally, we examine evolutionary patterns of amniote feeding mechanism and how correlates of chewing relate to the need to increase the efficiency of prey processing in order to facilitate increased metabolic rate and activity. PMID:11246036

  12. Prey-mediated behavioral responses of feeding blue whales in controlled sound exposure experiments.

    PubMed

    Friedlaender, A S; Hazen, E L; Goldbogen, J A; Stimpert, A K; Calambokidis, J; Southall, B L

    2016-06-01

    Behavioral response studies provide significant insights into the nature, magnitude, and consequences of changes in animal behavior in response to some external stimulus. Controlled exposure experiments (CEEs) to study behavioral response have faced challenges in quantifying the importance of and interaction among individual variability, exposure conditions, and environmental covariates. To investigate these complex parameters relative to blue whale behavior and how it may change as a function of certain sounds, we deployed multi-sensor acoustic tags and conducted CEEs using simulated mid-frequency active sonar (MFAS) and pseudo-random noise (PRN) stimuli, while collecting synoptic, quantitative prey measures. In contrast to previous approaches that lacked such prey data, our integrated approach explained substantially more variance in blue whale dive behavioral responses to mid-frequency sounds (r2 = 0.725 vs. 0.14 previously). Results demonstrate that deep-feeding whales respond more clearly and strongly to CEEs than those in other behavioral states, but this was only evident with the increased explanatory power provided by incorporating prey density and distribution as contextual covariates. Including contextual variables increases the ability to characterize behavioral variability and empirically strengthens previous findings that deep-feeding blue whales respond significantly to mid-frequency sound exposure. However, our results are only based on a single behavioral state with a limited sample size, and this analytical framework should be applied broadly across behavioral states. The increased capability to describe and account for individual response variability by including environmental variables, such as prey, that drive foraging behavior underscores the importance of integrating these and other relevant contextual parameters in experimental designs. Our results suggest the need to measure and account for the ecological dynamics of predator-prey

  13. Flexible echolocation behavior of trawling bats during approach of continuous or transient prey cues.

    PubMed

    Ubernickel, Kirstin; Tschapka, Marco; Kalko, Elisabeth K V

    2013-01-01

    Trawling bats use echolocation not only to detect and classify acoustically continuous cues originated from insects at and above water surfaces, but also to detect small water-dwelling prey items breaking the water surface for a very short time, producing only transient cues to be perceived acoustically. Generally, bats need to adjust their echolocation behavior to the specific task on hand, and because of the diversity of prey cues they use in hunting, trawling bats should be highly flexible in their echolocation behavior. We studied the adaptations in the behavior of Noctilio leporinus when approaching either a continuous cue or a transient cue that disappeared during the approach of the bat. Normally the bats reacted by dipping their feet in the water at the cue location. We found that the bats typically started to adapt their calling behavior at approximately 410 ms before prey contact in continuous cue trials, but were also able to adapt their approach behavior to stimuli onsets as short as 177 ms before contact, within a minimum reaction time of 50.9 ms in response to transient cues. In both tasks the approach phase ended between 32 and 53 ms before prey contact. Call emission always continued after the end of the approach phase until around prey contact. In some failed capture attempts, call emission did not cease at all after prey contact. Probably bats used spatial memory to dip at the original location of the transient cue after its disappearance. The duration of the pointed dips was significantly longer in transient cue trials than in continuous cue trials. Our results suggest that trawling bats possess the ability to modify their generally rather stereotyped echolocation behavior during approaches within very short reaction times depending on the sensory information available. PMID:23675352

  14. Prey-sensing and orientational behaviors of sand scorpions

    NASA Astrophysics Data System (ADS)

    Brownell, Philip

    2000-03-01

    Sand scorpions use exquisitely sensitive vibrational and chemosensory systems to locate prey and identify prospective mates active on the sand surface. Prey location is determined by input to a static array of 8 vibration-sensitive receptors, each responding as phase-locked accelerometers to compressional and surface waves conducted through sand. Angular orientation of the target is determined from passing surface (Rayleigh) waves, target distance possibly from the time delay between arrival of compressional and surface waves. For localization and identification of prospective mates, male scorpions use sexually dimorphic chemosensory appendages, the pectines, which are swept over a static stimulus field (chemical trail deposited on sand). These organs support a 2D array of closely-spaced (freq = 100/mm) sensilla containing more than 10^6 neurons, all projecting with great topographic precision to the central nervous system. Movement of this sensory array over a static stimulus field creates timing within the sensory signal. The potential importance of timing as a means of increasing sensitivity and selectivity of sensory response in two distinctly different modes is discussed.

  15. Specialized prey selection behavior of two East African assassin bugs, Scipinnia repax and Nagusta sp. that prey on social jumping spiders.

    PubMed

    Jackson, Robert R; Salm, Kathryn; Nelson, Ximena J

    2010-01-01

    The prey choice behavior and predatory strategies of two East African assassin bugs, Scipinnia repax (Stäl 1961) and Nagusta sp. (Hemiptera: Reduviidae), were investigated in the field and the laboratory. Both of these species are from the subfamily Harpactorinae and specialize in eating spiders. They prey especially often on social jumping spiders (Salticidae) that build nest complexes (nests connected by silk) in vegetation near the shoreline of Lake Victoria. Both reduviid species associate with these nest complexes and prey on the resident salticids. Nagusta sp., but not S. repax, form groups on nest complexes with 2-3 individuals of Nagusta sometimes feeding together on a single salticid. In addition to social salticids, Nagusta sp. preys on Portia africana, an araneophagic salticid that often invades the same nest complexes. S. repax preys on salticid eggs and also on Nagusta. Although they avoid ants, Nagusta and especially S. repax prey on ant-mimicking salticids, suggesting that sensory modalities other than vision play a dominant role in prey detection. PMID:20673067

  16. Specialized Prey Selection Behavior of Two East African Assassin Bugs, Scipinnia repax and Nagusta sp. that Prey on Social Jumping Spiders

    PubMed Central

    Jackson, Robert R.; Salm, Kathryn; Nelson, Ximena J.

    2010-01-01

    The prey choice behavior and predatory strategies of two East African assassin bugs, Scipinnia repax (Stäl 1961) and Nagusta sp. (Hemiptera: Reduviidae), were investigated in the field and the laboratory. Both of these species are from the subfamily Harpactorinae and specialize in eating spiders. They prey especially often on social jumping spiders (Salticidae) that build nest complexes (nests connected by silk) in vegetation near the shoreline of Lake Victoria. Both reduviid species associate with these nest complexes and prey on the resident salticids. Nagusta sp., but not S. repax, form groups on nest complexes with 2–3 individuals of Nagusta sometimes feeding together on a single salticid. In addition to social salticids, Nagusta sp. preys on Portia africana, an araneophagic salticid that often invades the same nest complexes. S. repax preys on salticid eggs and also on Nagusta. Although they avoid ants, Nagusta and especially S. repax prey on ant-mimicking salticids, suggesting that sensory modalities other than vision play a dominant role in prey detection. PMID:20673067

  17. Prey capture behavior evoked by simple visual stimuli in larval zebrafish.

    PubMed

    Bianco, Isaac H; Kampff, Adam R; Engert, Florian

    2011-01-01

    Understanding how the nervous system recognizes salient stimuli in the environment and selects and executes the appropriate behavioral responses is a fundamental question in systems neuroscience. To facilitate the neuroethological study of visually guided behavior in larval zebrafish, we developed "virtual reality" assays in which precisely controlled visual cues can be presented to larvae whilst their behavior is automatically monitored using machine vision algorithms. Freely swimming larvae responded to moving stimuli in a size-dependent manner: they directed multiple low amplitude orienting turns (∼20°) toward small moving spots (1°) but reacted to larger spots (10°) with high-amplitude aversive turns (∼60°). The tracking of small spots led us to examine how larvae respond to prey during hunting routines. By analyzing movie sequences of larvae hunting paramecia, we discovered that all prey capture routines commence with eye convergence and larvae maintain their eyes in a highly converged position for the duration of the prey-tracking and capture swim phases. We adapted our virtual reality assay to deliver artificial visual cues to partially restrained larvae and found that small moving spots evoked convergent eye movements and J-turns of the tail, which are defining features of natural hunting. We propose that eye convergence represents the engagement of a predatory mode of behavior in larval fish and serves to increase the region of binocular visual space to enable stereoscopic targeting of prey. PMID:22203793

  18. Prey Capture Behavior Evoked by Simple Visual Stimuli in Larval Zebrafish

    PubMed Central

    Bianco, Isaac H.; Kampff, Adam R.; Engert, Florian

    2011-01-01

    Understanding how the nervous system recognizes salient stimuli in the environment and selects and executes the appropriate behavioral responses is a fundamental question in systems neuroscience. To facilitate the neuroethological study of visually guided behavior in larval zebrafish, we developed “virtual reality” assays in which precisely controlled visual cues can be presented to larvae whilst their behavior is automatically monitored using machine vision algorithms. Freely swimming larvae responded to moving stimuli in a size-dependent manner: they directed multiple low amplitude orienting turns (∼20°) toward small moving spots (1°) but reacted to larger spots (10°) with high-amplitude aversive turns (∼60°). The tracking of small spots led us to examine how larvae respond to prey during hunting routines. By analyzing movie sequences of larvae hunting paramecia, we discovered that all prey capture routines commence with eye convergence and larvae maintain their eyes in a highly converged position for the duration of the prey-tracking and capture swim phases. We adapted our virtual reality assay to deliver artificial visual cues to partially restrained larvae and found that small moving spots evoked convergent eye movements and J-turns of the tail, which are defining features of natural hunting. We propose that eye convergence represents the engagement of a predatory mode of behavior in larval fish and serves to increase the region of binocular visual space to enable stereoscopic targeting of prey. PMID:22203793

  19. Prey-Capture Strategies of Fish-Hunting Cone Snails: Behavior, Neurobiology and Evolution.

    PubMed

    Olivera, Baldomero M; Seger, Jon; Horvath, Martin P; Fedosov, Alexander E

    2015-09-01

    The venomous fish-hunting cone snails (Conus) comprise eight distinct lineages evolved from ancestors that preyed on worms. In this article, we attempt to reconstruct events resulting in this shift in food resource by closely examining patterns of behavior, biochemical agents (toxins) that facilitate prey capture and the combinations of toxins present in extant species. The first sections introduce three different hunting behaviors associated with piscivory: 'taser-and-tether', 'net-engulfment' and 'strike-and-stalk'. The first two fish-hunting behaviors are clearly associated with distinct groups of venom components, called cabals, which act in concert to modify the behavior of prey in a specific manner. Derived fish-hunting behavior clearly also correlates with physical features of the radular tooth, the device that injects these biochemical components. Mapping behavior, biochemical components and radular tooth features onto phylogenetic trees shows that fish-hunting behavior emerged at least twice during evolution. The system presented here may be one of the best examples where diversity in structure, physiology and molecular features were initially driven by particular pathways selected through behavior. PMID:26397110

  20. Are single odorous components of a predator sufficient to elicit defensive behaviors in prey species?

    PubMed Central

    Apfelbach, Raimund; Parsons, Michael H.; Soini, Helena A.; Novotny, Milos V.

    2015-01-01

    When exposed to the odor of a sympatric predator, prey animals typically display escape or defensive responses. These phenomena have been well-documented, especially in rodents, when exposed to the odor of a cat, ferret, or fox. As a result of these experiments new discussions center on the following questions: (1) is a single volatile compound such as a major or a minor mixture constituent in urine or feces, emitted by the predator sufficient to cause defensive reactions in a potential prey species or (2) is a whole array of odors required to elicit a response and (3) will the relative size or escapability of the prey as compared to the predator influence responsiveness. Most predator-prey studies on this topic have been performed in the laboratory or under semi-natural conditions. Field studies could help to find answers to these questions. Australian mammals are completely naïve toward the introduced placental carnivores. That offers ideal opportunities to analyze in the field the responses of potential prey species to unknown predator odors. During the last decades researchers have accumulated an enormous amount of data exploring the effects of eutherian predator odors on native marsupial mammals. In this review, we will give a survey about the development of olfactory research, chemical signals and their influence on the behavior and—in some cases—physiology of prey species. In addition, we report on the effects of predator odor experiments performed under natural conditions in Australia. When studying all these literature we learned that data gained under controlled laboratory conditions elucidate the role of individual odors on brain structures and ultimately on a comparatively narrow range behaviors. In contrast to single odors odor arrays mimic much more the situation prey animals are confronted to in nature. Therefore, a broad range of methodology—from chemistry to ecology including anatomy, physiology, and behavior—is needed to understand all

  1. Feeding State Modulates Behavioral Choice and Processing of Prey Stimuli in the Zebrafish Tectum.

    PubMed

    Filosa, Alessandro; Barker, Alison J; Dal Maschio, Marco; Baier, Herwig

    2016-05-01

    Animals use the sense of vision to scan their environment, respond to threats, and locate food sources. The neural computations underlying the selection of a particular behavior, such as escape or approach, require flexibility to balance potential costs and benefits for survival. For example, avoiding novel visual objects reduces predation risk but negatively affects foraging success. Zebrafish larvae approach small, moving objects ("prey") and avoid large, looming objects ("predators"). We found that this binary classification of objects by size is strongly influenced by feeding state. Hunger shifts behavioral decisions from avoidance to approach and recruits additional prey-responsive neurons in the tectum, the main visual processing center. Both behavior and tectal function are modulated by signals from the hypothalamic-pituitary-interrenal axis and the serotonergic system. Our study has revealed a neuroendocrine mechanism that modulates the perception of food and the willingness to take risks in foraging decisions. PMID:27146269

  2. Prey-tracking behavior in the invasive terrestrial planarian Platydemus manokwari (Platyhelminthes, Tricladida)

    NASA Astrophysics Data System (ADS)

    Iwai, Noriko; Sugiura, Shinji; Chiba, Satoshi

    2010-11-01

    Platydemus manokwari is a broadly distributed invasive terrestrial flatworm that preys heavily on land snails and has been credited with the demise of numerous threatened island faunas. We examined whether P. manokwari tracks the mucus trails of land snail prey, investigated its ability to determine trail direction, and evaluated prey preference among various land snail species. A plastic treatment plate with the mucus trail of a single species and a control plate without the trail were placed side by side at the exit of cages housing P. manokwari. All trials were then videotaped overnight. The flatworms moved along plates with mucus trails, but did not respond to plates without trails, blank control (distilled water), or with conspecific flatworm trails. When presented at the midpoint of a snail mucus trail, the flatworms followed the trail in a random direction. The flatworms showed a preference when choosing between two plates, each with a mucus trail of different land snail species. Our results suggest that P. manokwari follows snail mucus trails based on chemical cues to increase the chance of encountering prey; however, trail-tracking behavior showed no directionality.

  3. The future of behavior therapy

    PubMed Central

    Gelder, Michael

    1997-01-01

    Although behavior therapy is designed to modify observable behaviors, it also brings about cognitive change. To achieve the best results with behavior therapy, it is sometimes necessary to combine it with cognitive procedures. The author gives examples of the uses of behavior therapy on its own and as combined cognitive-behavior therapy. These treatments have been tested extensively in clinical trials, and they are brief and highly suitable for use in managed care. Future developments are likely to include closer integration with pharmacotherapy and further extension into the field of behavioral medicine. PMID:9292442

  4. The scent of wolves: pyrazine analogs induce avoidance and vigilance behaviors in prey.

    PubMed

    Osada, Kazumi; Miyazono, Sadaharu; Kashiwayanagi, Makoto

    2015-01-01

    The common gray wolf (Canis lupus) is an apex predator located at the top of the food chain in the Northern Hemisphere. It preys on rodents, rabbits, ungulates, and many other kinds of mammal. However, the behavioral evidence for, and the chemical basis of, the fear-inducing impact of wolf urine on prey are unclear. Recently, the pyrazine analogs 2, 6-dimethylpyrazine, 2, 3, 5-trimethylpyrazine and 3-ethyl-2, 5-dimethyl pyrazine were identified as kairomones in the urine of wolves. When mice were confronted with a mixture of purified pyrazine analogs, vigilance behaviors, including freezing and excitation of neurons at the accessory olfactory bulb, were markedly increased. Additionally, the odor of the pyrazine cocktail effectively suppressed the approach of deer to a feeding area, and for those close to the feeding area elicited fear-related behaviors such as the "tail-flag," "flight," and "jump" actions. In this review, we discuss the transfer of chemical information from wolf to prey through the novel kairomones identified in wolf urine and also compare the characteristics of wolf kairomones with other predator-produced kairomones that affect rodents. PMID:26500485

  5. The scent of wolves: pyrazine analogs induce avoidance and vigilance behaviors in prey

    PubMed Central

    Osada, Kazumi; Miyazono, Sadaharu; Kashiwayanagi, Makoto

    2015-01-01

    The common gray wolf (Canis lupus) is an apex predator located at the top of the food chain in the Northern Hemisphere. It preys on rodents, rabbits, ungulates, and many other kinds of mammal. However, the behavioral evidence for, and the chemical basis of, the fear-inducing impact of wolf urine on prey are unclear. Recently, the pyrazine analogs 2, 6-dimethylpyrazine, 2, 3, 5-trimethylpyrazine and 3-ethyl-2, 5-dimethyl pyrazine were identified as kairomones in the urine of wolves. When mice were confronted with a mixture of purified pyrazine analogs, vigilance behaviors, including freezing and excitation of neurons at the accessory olfactory bulb, were markedly increased. Additionally, the odor of the pyrazine cocktail effectively suppressed the approach of deer to a feeding area, and for those close to the feeding area elicited fear-related behaviors such as the “tail-flag,” “flight,” and “jump” actions. In this review, we discuss the transfer of chemical information from wolf to prey through the novel kairomones identified in wolf urine and also compare the characteristics of wolf kairomones with other predator-produced kairomones that affect rodents. PMID:26500485

  6. Behavioral responses of native prey to disparate predators: naiveté and predator recognition.

    PubMed

    Anson, Jennifer R; Dickman, Chris R

    2013-02-01

    It is widely accepted that predator recognition and avoidance are important behaviors in allowing prey to mitigate the impacts of their predators. However, while prey species generally develop anti-predator behaviors through coevolution with predators, they sometimes show accelerated adoption of these behaviors under strong selection pressure from novel species. We used a field manipulation experiment to gauge the ability of the common ringtail possum (Pseudocheirus peregrinus), a semi-arboreal Australian marsupial, to recognize and respond to olfactory cues of different predator archetypes. We predicted that ringtails would display stronger anti-predator behaviors to cues of the invasive European red fox (Vulpes vulpes) in areas where fox impacts had been greatest, and to cues of the native lace monitor (Varanus varius) in areas of sympatry compared with allopatry. We found that ringtails fled quickly and were more alert when exposed to the fecal odors of both predators compared to neutral and pungent control odors, confirming that predator odors are recognized and avoided. However, these aversive responses were similar irrespective of predator presence or level of impact. These results suggest that selection pressure from the fox has been sufficient for ringtails to develop anti-predator behaviors over the few generations since foxes have become established. In contrast, we speculate that aversive responses by ringtails to the lace monitor in areas where this predator is absent reflect recent coexistence of the two species. We conclude that rapid evolution of anti-predator behaviors may occur when selection is strong. The maintenance of these behaviors should allow re-establishment of predator-prey relationships if the interactants regain sympatry via range shifts or management actions to reintroduce them to their former ranges. PMID:22865005

  7. Possible neural network mediating jaw opening during prey-catching behavior of the frog.

    PubMed

    Kovalecz, Gabriella; Kecskes, Szilvia; Birinyi, András; Matesz, Clara

    2015-10-01

    The prey-catching behavior of the frog is a complex, well-timed sequence of stimulus response chain of movements. After visual analysis of the prey, a size dependent program is selected in the motor pattern generator of the brainstem. Besides this predetermined feeding program, various direct and indirect sensory inputs provide flexible adjustment for the optimal contraction of the executive muscles. The aim of the present study was to investigate whether trigeminal primary afferents establish direct contacts with the jaw opening motoneurons innervated by the facial nerve. The experiments were carried out on Rana esculenta (Pelophylax esculentus), where the trigeminal and facial nerves were labeled simultaneously with different fluorescent dyes. Using a confocal laser scanning microscope, close appositions were detected between trigeminal afferent fibers and somatodendritic components of the facial motoneurons. Quantitative analysis revealed that the majority of close contacts were encountered on the dendrites of facial motoneurons and approximately 10% of them were located on the perikarya. We suggest that the identified contacts between the trigeminal afferents and facial motoneurons presented here may be one of the morphological substrate in the feedback and feedforward modulation of the rapidly changing activity of the jaw opening muscle during the prey-catching behavior. PMID:26444079

  8. Behavior of fish predators and their prey: habitat choice between open water and dense vegetation

    USGS Publications Warehouse

    Savino, Jacqueline F.; Stein, Roy A.

    1989-01-01

    Behavior of largemouth bass, Micropterus salmoides, and northern pike, Esox lucius, foraging on fathead minnows, Pimephales promelas, or bluegills, Lepomis macrochirus, was quantified in pools with 50% cover (half the pool had artificial stems at a density of 1000 stems m−2). Both predators spent most of their time in the vegetation. Largemouth bass searched for bluegills and ambushed minnows, whereas the relatively immobile northern pike ambushed all prey. Minnows were closer to predators and were captured more frequently than bluegills. Even when minnows dispersed, they moved continually and eventually wandered within striking distance of a predator. Bluegills dispersed in the cover with predators. Bass captured the few bluegills that strayed into the open and pike captured those that approached too closely in the cover. The ability of predators to capture prey while residing in habitats containing patches of dense cover may explain their residence in areas often considered to be poor ones for foraging.

  9. Impacts of Human Disturbance on Large Prey Species: Do Behavioral Reactions Translate to Fitness Consequences?

    PubMed Central

    Leblond, Mathieu; Dussault, Christian; Ouellet, Jean-Pierre

    2013-01-01

    Anthropogenic disturbances have been demonstrated to affect animal behavior, distribution, and abundance, but assessment of their impacts on fitness-related traits has received little attention. We hypothesized that human activities and infrastructure cause a decrease in the individual performance of preys because of anthropogenically enhanced predation risk. We evaluated the impacts of commercial logging and road networks on the fitness of a large herbivore known to be sensitive to human disturbance: the forest-dwelling woodland caribou (Rangifer tarandus caribou). For 8 consecutive years (2004–2011) we monitored 59 individuals using GPS telemetry in the Charlevoix region of Québec, Canada. We also used Very High Frequency telemetry locations collected on 28 individuals from 1999–2000. We related habitat selection of adult caribou at various spatio-temporal scales to their probability of dying from predation, and to indices of their reproductive success and energy expenditure. The probability that adult caribou died from predation increased with the proportion of recent disturbances (including cutblocks ≤5 years old) in their annual home range. The respective effects of increasing paved and forestry road densities depended upon the overall road density within the home range of caribou. At a finer scale of 10 to 15 days before their death, caribou that were killed by a predator selected for recent disturbances more than individuals that survived, and avoided old mature conifer stands. The home range area of caribou increased with road density. Finally, the composition of the home range of females had no effect on their reproductive success. We show that human activities and infrastructure may influence the individual performance of large prey species in highly managed regions. We outline the need to consider the full set of impacts that human development may have on threatened animal populations, with particular emphasis on predator-prey relationships and

  10. Modeling the behavior of the northern anchovy, Engraulis mordax, as a schooling predator exploiting patchy prey

    NASA Astrophysics Data System (ADS)

    Nonacs, Peter; Smith, Paul E.; Bouskila, Amos; Luttbeg, Barney

    Extensive data sets on the bioenergetics of the northern anchovy, Engraulis mordax, and the patchy food distribution in its natural habitat allow its foraging dynamics to be inferred by modeling using techniques from population biology and behavioral ecology. The behavioral model consistently predicts that E. mordax grows much more slowly than would be expected with a pure, net-energy intake rate maximization strategy. The reduced growth rates could result from the fish avoiding zooplankton patches, where they are under increased predation risk, by swimming slowly in the waters between zooplankton patches. The combinations of growth rates and daily instantaneous mortality rates generated by the behavioral model are internally consistent with a Lefkovitch matrix population model, which includes an early juvenile stage of a stable and stationary population. Several novel and testable predictions are made by the behavioral model, including: (1) anchovies swim very slowly between zooplankton patch encounters; (2) within a patch fish swim very rapidly while searching for prey; and (3) fish often leave zooplankton patches before totally filling their stomachs. Given these encouraging initial results, the behavioral modeling approach appears to be a valuable technique for examining how potential habitat changes due to global warming may affect fish behavior and populations. Several such scenarios are proposed and discussed.

  11. Comparison of wing morphology in three birds of prey: correlations with differences in flight behavior.

    PubMed

    Corvidae, Elaine L; Bierregaard, Richard O; Peters, Susan E

    2006-05-01

    Flight is the overriding characteristic of birds that has influenced most of their morphological, physiological, and behavioral features. Flight adaptations are essential for survival in the wide variety of environments that birds occupy. Therefore, locomotor structure, including skeletal and muscular characteristics, is adapted to reflect the flight style necessitated by different ecological niches. Red-tailed hawks (Buteo jamaicensis) soar to locate their prey, Cooper's hawks (Accipiter cooperii) actively chase down avian prey, and ospreys (Pandion haliaetus) soar and hover to locate fish. In this study, wing ratios, proportions of skeletal elements, and relative sizes of selected flight muscles were compared among these species. Oxidative and glycolytic enzyme activities of several muscles were also analyzed via assays for citrate synthase (CS) and for lactate dehydrogenase (LDH). It was found that structural characteristics of these three raptors differ in ways consistent with prevailing aerodynamic models. The similarity of enzymatic activities among different muscles of the three species shows low physiological differentiation and suggests that wing architecture may play a greater role in determining flight styles for these birds. PMID:16477604

  12. Congruence between muscle activity and kinematics in a convergently derived prey-processing behavior.

    PubMed

    Konow, Nicolai; Camp, Ariel L; Sanford, Christopher P J

    2008-08-01

    Quantification of anatomical and physiological characteristics of the function of a musculoskeletal system may yield a detailed understanding of how the organizational levels of morphology, biomechanics, kinematics, and muscle activity patterns (MAPs) influence behavioral diversity. Using separate analyses of these organizational levels in representative study taxa, we sought patterns of congruence in how organizational levels drive behavioral modulation in a novel raking prey-processing behavior found in teleosts belonging to two evolutionarily distinct lineages. Biomechanically divergent prey (elusive, robust goldfish and sedentary, malleable earthworms) were fed to knifefish, Chitala ornata (Osteoglossomorpha) and brook trout, Salvelinus fontinalis (Salmoniformes). Electromyography recorded MAPs from the hyoid protractor, jaw adductor, sternohyoideus, epaxialis, and hypaxialis musculature, while sonomicrometry sampled deep basihyal kinesis and contractile length dynamics in the basihyal protractor and retractor muscles. Syntheses of our results with recent analyses of cranial morphology and raking kinematics showed that raking in Salvelinus relies on an elongated cranial out lever, extensive cranial elevation and a curved cleithrobranchial ligament (CBL), and that both raking MAPs and kinematics remain entirely unmodulated-a highly unusual trait, particularly among feeding generalists. Chitala had a shorter CBL and a raking power stroke involving increased retraction of the elongated pectoral girdle during raking on goldfish. The raking MAP was also modulated in Chitala, involving an extensive overlap between muscle activity of the preparatory and power stroke phases, driven by shifts in hypaxial timing and recruitment of the hyoid protractor muscle. Sonomicrometry revealed that the protractor hyoideus muscle stored energy from retraction of the pectoral girdle for ca. 5-20 ms after onset of the power stroke and then hyper-extended. This mechanism of elastic

  13. Prey foraging behavior, seasonality and time-budgets in black lion tamarins, Leontopithecus chrysopygus (Mikan 1823) (Mammalia, Callitrichidae).

    PubMed

    Keuroghlian, A; Passos, F C

    2001-08-01

    Foraging behavior, seasonality and time-budgets in the Black Lion Tamarin (L. chrysopygus) was observed in the Caetetus Ecological Station, South-eastern Brazil, during 83 days between November 1988 to October 1990. For the full dry season we found that animal prey represented 11.2% of the black lion tamarin diet, while during the wet season they represented 1.9%. Foraging behavior made up 19.8% of their total activity in the dry season and only 12.8% in the wet season. These results point out that animal prey are relatively more important during the dry season, due to reduced availability of other resources, e.g. fruits, and that a greater foraging effort is required when a larger proportion of the diet is animal prey. PMID:11706573

  14. Effect of acute low body temperature on predatory behavior and prey-capture efficiency in a plethodontid salamander.

    PubMed

    Marvin, Glenn A; Davis, Kayla; Dawson, Jacob

    2016-05-01

    The low-temperature limit for feeding in some salamander species (Desmognathus, Plethodontidae) has been inferred from field studies of seasonal variation in salamander activity and gut contents, which could not determine whether feeding is more dependent on environmental conditions influencing salamander foraging behavior or prey availability and movement. We performed two controlled laboratory experiments to examine the effect of short-term (acute) low body temperature on predatory behavior and prey-capture efficiency in a semiaquatic plethodontid salamander (Desmognathus conanti). In the first experiment, we quantified variation in the feeding responses of cold salamanders (at 1, 3, 5 and 7°C) to a video recording of a walking, warm (15°C) cricket to determine the lower thermal limit for predatory behavior, independent of any temperature effect on movement of prey. Experimental-group salamanders exhibited vigorous feeding responses at 5 and 7°C, large variation in feeding responses both among and within individuals (over time) at 3°C, and little to no feeding response at 1°C. Feeding responses at both 1 and 3°C were significantly less than at each higher temperature, whereas responses of control-group individuals at 15°C did not vary over time. In the second experiment, we quantified feeding by cold salamanders (at 3, 5, 7 and 11°C) on live, warm crickets to examine thermal effects on prey-capture ability. The mean feeding response to live crickets was significantly less at 3°C than at higher temperatures; however, 50% of salamanders captured and ingested prey with high efficiency at this temperature. We conclude that many individuals stalk and capture prey at very low temperatures (down to 3°C). Our results support a growing body of data that indicate many plethodontid salamanders feed at temperatures only a few degrees above freezing. PMID:26939728

  15. Interspecific variation in prey capture behavior by co-occurring Nepenthes pitcher plants

    PubMed Central

    Chin, Lijin; Chung, Arthur YC; Clarke, Charles

    2014-01-01

    Pitcher plants of the genus Nepenthes capture a wide range of arthropod prey for nutritional benefit, using complex combinations of visual and olfactory signals and gravity-driven pitfall trapping mechanisms. In many localities throughout Southeast Asia, several Nepenthes different species occur in mixed populations. Often, the species present at any given location have strongly divergent trap structures and preliminary surveys indicate that different species trap different combinations of arthropod prey, even when growing at the same locality. On this basis, it has been proposed that co-existing Nepenthes species may be engaged in niche segregation with regards to arthropod prey, avoiding direct competition with congeners by deploying traps that have modifications that enable them to target specific prey types. We examined prey capture among 3 multi-species Nepenthes populations in Borneo, finding that co-existing Nepenthes species do capture different combinations of prey, but that significant interspecific variations in arthropod prey combinations can often be detected only at sub-ordinal taxonomic ranks. In all lowland Nepenthes species examined, the dominant prey taxon is Formicidae, but montane Nepenthes trap few (or no) ants and 2 of the 3 species studied have evolved to target alternative sources of nutrition, such as tree shrew feces. Using similarity and null model analyses, we detected evidence for niche segregation with regards to formicid prey among 5 lowland, sympatric Nepenthes species in Sarawak. However, we were unable to determine whether these results provide support for the niche segregation hypothesis, or whether they simply reflect unquantified variation in heterogeneous habitats and/or ant communities in the study sites. These findings are used to propose improvements to the design of field experiments that seek to test hypotheses about targeted prey capture patterns in Nepenthes. PMID:24481246

  16. On the amphibious food uptake and prey manipulation behavior in the Balkan-Anatolian crested newt (Triturus ivanbureschi, Arntzen and Wielstra, 2013).

    PubMed

    Lukanov, Simeon; Tzankov, Nikolay; Handschuh, Stephan; Heiss, Egon; Naumov, Borislav; Natchev, Nikolay

    2016-06-01

    Feeding behavior in salamanders undergoing seasonal habitat shifts poses substantial challenges caused by differences in the physical properties of air and water. Adapting to these specific environments, urodelans use suction feeding predominantly under water as opposed to lingual food prehension on land. This study aims to determine the functionality of aquatic and terrestrial feeding behavior in the Balkan-Anatolian crested newt (Triturus ivanbureschi) in its terrestrial stage. During the terrestrial stage, these newts feed frequently in water where they use hydrodynamic mechanisms for prey capture. On land, prey apprehension is accomplished mainly by lingual prehension, while jaw prehension seems to be the exception (16.67%) in all terrestrial prey capture events. In jaw prehension events there was no detectable depression of the hyo-lingual complex. The success of terrestrial prey capture was significantly higher when T. ivanbureschi used lingual prehension. In addition to prey capture, we studied the mechanisms involved in the subduction of prey. In both media, the newts frequently used a shaking behavior to immobilize the captured earthworms. Apparently, prey shaking constitutes a significant element in the feeding behavior of T. ivanbureschi. Prey immobilization was applied more frequently during underwater feeding, which necessitates a discussion of the influence of the feeding media on food manipulation. We also investigated the osteology of the cranio-cervical complex in T. ivanbureschi to compare it to that of the predominantly terrestrial salamandrid Salamandra salamandra. PMID:27013264

  17. Density-dependent predation influences the evolution and behavior of masquerading prey.

    PubMed

    Skelhorn, John; Rowland, Hannah M; Delf, Jon; Speed, Michael P; Ruxton, Graeme D

    2011-04-19

    Predation is a fundamental process in the interaction between species, and exerts strong selection pressure. Hence, anti-predatory traits have been intensively studied. Although it has long been speculated that individuals of some species gain protection from predators by sometimes almost-uncanny resemblances to uninteresting objects in the local environment (such as twigs or stones), demonstration of antipredatory benefits to such "masquerade" have only very recently been demonstrated, and the fundamental workings of this defensive strategy remain unclear. Here we use laboratory experiments with avian predators and twig-mimicking caterpillars as masqueraders to investigate (i) the evolutionary dynamics of masquerade; and (ii) the behavioral adaptations associated with masquerade. We show that the benefit of masquerade declines as the local density of masqueraders relative to their models (twigs, in our system) increases. This occurs through two separate mechanisms: increasing model density both decreased predators' motivation to search for masqueraders, and made masqueraders more difficult to detect. We further demonstrated that masquerading organisms have evolved complex microhabitat selection strategies that allow them to best exploit the density-dependent properties of masquerade. Our results strongly suggest the existence of opportunity costs associated with masquerade. Careful evaluation of such costs will be vital to the development of a fuller understanding of both the distribution of masquerade across taxa and ecosystems, and the evolution of the life history strategies of masquerading prey. PMID:21464318

  18. Effects of competitive prey capture on flight behavior and sonar beam pattern in paired big brown bats, Eptesicus fuscus

    PubMed Central

    Chiu, Chen; Reddy, Puduru Viswanadha; Xian, Wei; Krishnaprasad, Perinkulam S.; Moss, Cynthia F.

    2010-01-01

    Foraging and flight behavior of echolocating bats were quantitatively analyzed in this study. Paired big brown bats, Eptesicus fuscus, competed for a single food item in a large laboratory flight room. Their sonar beam patterns and flight paths were recorded by a microphone array and two high-speed cameras, respectively. Bats often remained in nearly classical pursuit (CP) states when one bat is following another bat. A follower can detect and anticipate the movement of the leader, while the leader has the advantage of gaining access to the prey first. Bats in the trailing position throughout the trial were more successful in accessing the prey. In this study, bats also used their sonar beam to monitor the conspecific's movement and to track the prey. Each bat tended to use its sonar beam to track the prey when it was closer to the worm than to another bat. The trailing bat often directed its sonar beam toward the leading bat in following flight. When two bats flew towards each other, they tended to direct their sonar beam axes away from each other, presumably to avoid signal jamming. This study provides a new perspective on how echolocating bats use their biosonar system to coordinate their flight with conspecifics in a group and how they compete for the same food source with conspecifics. PMID:20833928

  19. Brainstem circuits underlying the prey-catching behavior of the frog.

    PubMed

    Matesz, Klara; Kecskes, Szilvia; Bácskai, Tímea; Rácz, Éva; Birinyi, András

    2014-01-01

    Prey-catching behavior (PCB) of the frog consists of a sequence of movements as a stimulus-response chain of the behavioral pattern in which each action presents a signal for the subsequent event. The transformation of visual information into appropriate spatiotemporal patterns of motor activity is carried out by the motor pattern generators located in the brainstem reticular formation. The motor pattern generators provide input to the motoneurons either directly or via the last-order premotor interneurons (LOPI). Although the feeding program is predetermined in this way, various sensory mechanisms control the motor activity. By using neuronal labeling methods, we have studied the morphological details of sensorimotor integration related to the hypoglossal motoneurons to provide further insight into the neuronal circuits underlying the PCB in ranid frogs. Our major findings are as follows. (1) Dendrodendritic and dendrosomatic contacts established by the crossing dendrites of hypoglossal (XII) motoneurons may serve as a morphological option for co-activation, synchronization and proper timing of the bilateral activity of tongue muscles. The crossing dendrites may also provide a feedforward amplification of various signals to the XII motoneurons. The overlapping dendritic territories of the motoneurons innervating protractor and retractor muscles may facilitate the coordinated activities of the agonistic and antagonistic muscles. (2) The musculotopic organization of the XII motoneurons is reflected in the distribution of LOPI for the protractor and retractor muscles of the tongue. (3) Direct sensory inputs from the trigeminal, vestibular, glossopharyngeal-vagal, hypoglossal and spinal afferent fibers to the XII motoneurons may modulate the basic motor pattern and contribute to the plasticity of neuronal circuits. (4) The electrical couplings observed in the vestibulocerebellar neuronal circuits may synchronize and amplify the afferent signals. The combination of

  20. Phages Preying on Bacillus anthracis, Bacillus cereus, and Bacillus thuringiensis: Past, Present and Future

    PubMed Central

    Gillis, Annika; Mahillon, Jacques

    2014-01-01

    Many bacteriophages (phages) have been widely studied due to their major role in virulence evolution of bacterial pathogens. However, less attention has been paid to phages preying on bacteria from the Bacillus cereus group and their contribution to the bacterial genetic pool has been disregarded. Therefore, this review brings together the main information for the B. cereus group phages, from their discovery to their modern biotechnological applications. A special focus is given to phages infecting Bacillus anthracis, B. cereus and Bacillus thuringiensis. These phages belong to the Myoviridae, Siphoviridae, Podoviridae and Tectiviridae families. For the sake of clarity, several phage categories have been made according to significant characteristics such as lifestyles and lysogenic states. The main categories comprise the transducing phages, phages with a chromosomal or plasmidial prophage state, γ-like phages and jumbo-phages. The current genomic characterization of some of these phages is also addressed throughout this work and some promising applications are discussed here. PMID:25010767

  1. Phages preying on Bacillus anthracis, Bacillus cereus, and Bacillus thuringiensis: past, present and future.

    PubMed

    Gillis, Annika; Mahillon, Jacques

    2014-07-01

    Many bacteriophages (phages) have been widely studied due to their major role in virulence evolution of bacterial pathogens. However, less attention has been paid to phages preying on bacteria from the Bacillus cereus group and their contribution to the bacterial genetic pool has been disregarded. Therefore, this review brings together the main information for the B. cereus group phages, from their discovery to their modern biotechnological applications. A special focus is given to phages infecting Bacillus anthracis, B. cereus and Bacillus thuringiensis. These phages belong to the Myoviridae, Siphoviridae, Podoviridae and Tectiviridae families. For the sake of clarity, several phage categories have been made according to significant characteristics such as lifestyles and lysogenic states. The main categories comprise the transducing phages, phages with a chromosomal or plasmidial prophage state, γ-like phages and jumbo-phages. The current genomic characterization of some of these phages is also addressed throughout this work and some promising applications are discussed here. PMID:25010767

  2. Behavioral responses of predator-naïve dwarf hamsters (Phodopus campbelli) to odor cues of the European ferret fed with different prey species.

    PubMed

    Apfelbach, Raimund; Soini, Helena A; Vasilieva, Nina Y; Novotny, Milos V

    2015-07-01

    Many mammalian predators are able to identify their prey by odors and, vice versa, numerous prey species recognize predator odors as well. The present paper reports on the behavioral responses of predator-naïve dwarf hamsters (Phodopus campbelli) towards the urine odors of carnivorous ferrets, which were raised on either a chicken, mouse or hamster diet. Chemical composition from ferret urines of the different diet groups was analyzed, while quantitative differences in urinary volatile constituents were observed through capillary gas chromatography–mass spectrometry. In a Y-maze arrangement, hamsters were offered several two-choice odor discrimination tasks and their behavior was quantified. Hamsters were easily able to discriminate the urine odor of ferrets fed with mice against ferrets fed with hamsters. This is probably the first report indicating that a prey species can distinguish urine odors of even an unknown predator species that has been fed different prey species. The analytical data complemented behavioral assays. PMID:26066723

  3. The economics of protecting tiger populations: Linking household behavior to poaching and prey depletion

    USGS Publications Warehouse

    Damania, R.; Stringer, R.; Karanth, K.U.; Stith, B.

    2003-01-01

    The tiger (Panthera tigris) is classified as endangered and populations continue to decline. This paper presents a formal economic analysis of the two most imminent threats to the survival of wild tigers: poaching tigers and hunting their prey. A model is developed to examine interactions between tigers and farm households living in and around tiger habitats. The analysis extends the existing literature on tiger demography, incorporating predator-prey interactions and exploring the sensitivity of tiger populations to key economic parameters. The analysis aims to contribute to policy debates on how best to protect one of the world's most endangered wild cats.

  4. Predators and Prey

    ERIC Educational Resources Information Center

    Kramm, Kenneth R.

    1975-01-01

    Reviews basic concepts of predator-prey interaction, encourages the presentation of the predator's role and describes a model of predator behavior to be used in secondary school or college classes. (LS)

  5. Asymptotic behavior of a stochastic non-autonomous predator-prey model with impulsive perturbations

    NASA Astrophysics Data System (ADS)

    Wu, Ruihua; Zou, Xiaoling; Wang, Ke

    2015-03-01

    This paper is concerned with a stochastic non-autonomous Lotka-Volterra predator-prey model with impulsive effects. The asymptotic properties are examined. Sufficient conditions for persistence and extinction are obtained, our results demonstrate that the impulse has important effects on the persistence and extinction of the species. We also show that the solution is stochastically ultimate bounded under some conditions. Finally, several simulation figures are introduced to confirm our main results.

  6. Behavioral responses of batoid elasmobranchs to prey-simulating electric fields are correlated to peripheral sensory morphology and ecology.

    PubMed

    Bedore, Christine N; Harris, Lindsay L; Kajiura, Stephen M

    2014-04-01

    Electrosensory pore number, distribution, and sensitivity to prey-simulating electric fields have been described for many shark species. Electrosensory systems in batoids have received much less attention. Pore number and distribution have yet to be correlated to differences in sensitivity. However, pore number, pore distribution and sensitivity have been linked to behavior, diet, and morphology and follow species-specific trends. We report here that cownose rays have a greater number of pores than the yellow stingray, most of which are concentrated on the anterior ventral surface for both species. However, yellow stingrays have a broader arrangement of pores on both their dorsal and ventral surfaces than the cownose rays. Yellow stingrays demonstrated a median behavioral sensitivity to weak electric fields of 22nVcm(-1) and are among the most highly sensitive batoids studied to date. Cownose rays are less sensitive than all other elasmobranch species with a median sensitivity of 107nVcm(-1). As reported in previous studies, a higher pore number did not result in greater sensitivity. Cownose rays are benthopelagic schooling rays and may benefit from reduced sensitivity to bioelectric fields when they are surrounded by the bioelectric fields of conspecifics. Yellow stingrays, on the other hand, are typically solitary and bury in the substrate. A greater number of pores on their dorsal surface might improve detection of predators above them. Also, increased sensitivity and a broader distribution of pores may be beneficial as small prey items move past a buried ray. PMID:24290363

  7. Innate and Learned Prey-Searching Behavior in a Generalist Predator.

    PubMed

    Ardanuy, Agnès; Albajes, Ramon; Turlings, Ted C J

    2016-06-01

    Early colonization by Zyginidia scutellaris leafhoppers might be a key factor in the attraction and settling of generalist predators, such as Orius spp., in maize fields. In this paper, we aimed to determine whether our observations of early season increases in field populations of Orius spp. reflect a specific attraction to Z. scutellaris-induced maize volatiles, and how the responses of Orius predators to herbivore-induced volatiles (HIPVs) might be affected by previous experiences on plants infested by herbivorous prey. Therefore, we examined the innate and learned preferences of Orius majusculus toward volatiles from maize plants attacked by three potential herbivores with different feeding strategies: the leafhopper Z. scutellaris (mesophyll feeder), the lepidopteran Spodoptera littoralis (chewer), and another leafhopper Dalbulus maidis (phloem feeder). In addition, we examined the volatile profiles emitted by maize plants infested by the three herbivores. Our results show that predators exhibit a strong innate attraction to volatiles from maize plants infested with Z. scutellaris or S. littoralis. Previous predation experience in the presence of HIPVs influences the predator's odor preferences. The innate preference for plants with cell or tissue damage may be explained by these plants releasing far more volatiles than plants infested by the phloem-sucking D. maidis. However, a predation experience on D. maidis-infested plants increased the preference for D. maidis-induced maize volatiles. After O. majusculus experienced L3-L4 larvae (too large to serve as prey) on S. littoralis-infested plants, they showed reduced attraction toward these plants and an increased attraction toward D. maidis-infested plants. When offered young larvae of S. littoralis, which are more suitable prey, preference toward HIPVs was similar to that of naive individuals. The HIPVs from plants infested by herbivores with distinctly different feeding strategies showed distinguishable

  8. Observations on the Nesting and Prey of the Solitary Wasp, Tachysphex inconspicuus, with a Review of Nesting Behavior in the T. obscuripennis species group

    PubMed Central

    Kurczewski, Frank E.; Coville, Rollin E.; Schal, Coby

    2010-01-01

    The nesting behaviors of 10 females of Tachysphex inconspicuus (Kirby) (Hymenoptera: Crabronidae) were studied on a sandy, mowed lawn at the La Selva Biological Station in northeastern Costa Rica on 27–29 April 1980. Twenty-four completed nests were observed, excavated, and measured. The nests had oblique, short burrows leading to one or two shallow cells. Prey cockroaches belonging to 11 species of Chorisoneura and Riatia fulgida (Saussure) (Blattaria: Blattellidae), all tropical wet forest canopy indicator species, were removed from the cells, weighed, and identified. The cockroaches consisted mainly of adult females, selectively preyed upon over adult males and nymphs due to their larger sizes. The aggregate prey mass in cells was separable into prospective larger (heavier) female and smaller (lighter) male cells. Wasps usually oviposited on the heaviest cockroach in a cell, in most cases an adult female. Atypical genus behavior included (1) prey being carried to one side of the wasp and perhaps grasped by a hindleg during removal of the temporary entrance closure and nest entry and (2) wasp's egg being laid affixed to a forecoxal corium and extending backward in a longitudinally posteriad position across the prey's ventral thorax. A comparison with the nesting behavior of other species in the Tachysphex obscuripennis species group is made. PMID:21062142

  9. In vivo bite and grip forces, morphology and prey-killing behavior of North American accipiters (Accipitridae) and falcons (Falconidae).

    PubMed

    Sustaita, Diego; Hertel, Fritz

    2010-08-01

    Raptors exhibit a diversity of strategies to procure their prey but ultimately kill using their beaks and/or talons. Thus, bite and grip forces are ecologically important variables that have direct survival implications. Whereas hawks rely primarily on their feet for killing prey, falcons tend to employ their beaks. Consequently, falcons are expected to achieve relatively greater bite forces, and hawks are expected to generate relatively greater grip forces. Force estimates predicted from musculoskeletal morphology in a previous study indicated that falcons (Falco spp.) possess greater jaw force capabilities than accipiters (Accipiter spp.) but there were no clear differences in predicted grip-force capacity outside of differences in scaling. The objective of this study was to complement those results with measurements of in vivo forces by inducing captive and wild accipiters and falcons to bite and grasp force transducers. Bite force increased isometrically in both groups whereas grip force tended toward positive allometry. After adjusting for body mass, falcons produced greater bite forces, and accipiters produced greater grip forces. Thus, previous anatomical estimates of forces predicted the expected direction and magnitude of differences in bite forces but the overall greater in vivo grip forces of accipiters deviated from the pattern obtained from biomechanical estimates. Although the scaling relationships were similar between data sets, forces generated by live birds were consistently lower than those predicted from biomechanics. Estimated and in vivo jaw and digital forces were nevertheless correlated, and therefore provide an important link between morphology and killing behavior in these raptors. PMID:20639423

  10. The influence of habitat, prey abundance, sex, and breeding success on the ranging behavior of Prairie Falcons

    USGS Publications Warehouse

    Marzluff, J.M.; Kimsey, Bryan A.; Schueck, Linda S.; McFadzen, Mary E.; Vekasy, M.S.; Bednarz, James C.

    1997-01-01

    We studied the ranging behavior and habitat selection of radio-tagged Prairie Falcons (Falco mexicanus) during the breeding season in southwestern Idaho. The distribution and numbers of Townsend's ground squirrels (Spermophilus townsendii), the primary prey of Prairie Falcons in our study area, varied in response to drought during the study period. Prairie Falcons ranged over large areas (ca. 300 km2) and increased their foraging ranges in response to declining ground squirrels. Reptiles and birds were preyed upon most frequently when squirrels were rare. Males and females differed little in their use of space. Successful pairs ranged over smaller areas than non-nesters and unsuccessful pairs. Falcons nesting near habitat most suitable for ground squirrels ranged over smaller areas than those nesting farther from such habitat. Home ranges contained significantly more winterfat (Ceratoides lanata) and native perennial grasses (especially Poa secunda), and significantly less salt desert shrubs and exotic annual grasses than expected based on availability. Salt desert shrubs were found less than expected, based on availability in core areas within home ranges. Selection for winterfat and bluegrass in core areas was contingent upon selection at the larger scale of the home range; falcons with home ranges containing more winterfat and bluegrass than expected based on availability were less selective in their placement of core areas with respect to these habitats. We believe salient features of Prairie Falcon home ranges result largely from patchy distribution of landscape features associated with different densities and availabilities of Townsend's ground squirrels.

  11. Vulnerability and behavioral response to ultraviolet radiation in the components of a foliar mite prey-predator system

    NASA Astrophysics Data System (ADS)

    Tachi, Fuyuki; Osakabe, Masahiro

    2012-12-01

    Ambient ultraviolet-B (UVB) radiation impacts plant-dwelling arthropods including herbivorous and predatory mites. However, the effects of UVB on prey-predator systems, such as that between the herbivorous spider mite and predatory phytoseiid mite, are poorly understood. A comparative study was conducted to determine the vulnerability and behavioral responses of these mites to ultraviolet (UV) radiation. First, we analyzed dose-response (cumulative irradiance-mortality) curves for the eggs of phytoseiid mites ( Neoseiulus californicus, Neoseiulus womersleyi, and Phytoseiulus persimilis) and the spider mite ( Tetranychus urticae) to UVB radiation from a UV lamp. This indicated that the phytoseiid mites were more vulnerable than the spider mite, although P. persimilis was slightly more tolerant than the other two phytoseiid mites. Second, we compared the avoidance behavior of adult female N. californicus and two spider mite species ( T. urticae, a lower leaf surface user; Panonychus citri, an upper leaf surface user) in response to solar UV and visible light. N. californicus actively avoided both types of radiation, whereas P. citri showed only minimal avoidance behavior. T. urticae actively avoided UV as well as N. californicus but exhibited a slow response to visible light as well as P. citri. Such variation in vulnerability and avoidance behavior accounts for differences in the species adaptations to solar UVB radiation. This may be the primary factor determining habitat use among these mites on host plant leaves, subsequently affecting accessibility by predators and also intraguild competition.

  12. The Role of Motion Extrapolation in Amphibian Prey Capture

    PubMed Central

    2015-01-01

    Sensorimotor delays decouple behaviors from the events that drive them. The brain compensates for these delays with predictive mechanisms, but the efficacy and timescale over which these mechanisms operate remain poorly understood. Here, we assess how prediction is used to compensate for prey movement that occurs during visuomotor processing. We obtained high-speed video records of freely moving, tongue-projecting salamanders catching walking prey, emulating natural foraging conditions. We found that tongue projections were preceded by a rapid head turn lasting ∼130 ms. This motor lag, combined with the ∼100 ms phototransduction delay at photopic light levels, gave a ∼230 ms visuomotor response delay during which prey typically moved approximately one body length. Tongue projections, however, did not significantly lag prey position but were highly accurate instead. Angular errors in tongue projection accuracy were consistent with a linear extrapolation model that predicted prey position at the time of tongue contact using the average prey motion during a ∼175 ms period one visual latency before the head movement. The model explained successful strikes where the tongue hit the fly, and unsuccessful strikes where the fly turned and the tongue hit a phantom location consistent with the fly's earlier trajectory. The model parameters, obtained from the data, agree with the temporal integration and latency of retinal responses proposed to contribute to motion extrapolation. These results show that the salamander predicts future prey position and that prediction significantly improves prey capture success over a broad range of prey speeds and light levels. SIGNIFICANCE STATEMENT Neural processing delays cause actions to lag behind the events that elicit them. To cope with these delays, the brain predicts what will happen in the future. While neural circuits in the retina and beyond have been suggested to participate in such predictions, few behaviors have been

  13. Elevated CO2 Affects Predator-Prey Interactions through Altered Performance

    PubMed Central

    Allan, Bridie J. M.; Domenici, Paolo; McCormick, Mark I.; Watson, Sue-Ann; Munday, Philip L.

    2013-01-01

    Recent research has shown that exposure to elevated carbon dioxide (CO2) affects how fishes perceive their environment, affecting behavioral and cognitive processes leading to increased prey mortality. However, it is unclear if increased mortality results from changes in the dynamics of predator-prey interactions or due to prey increasing activity levels. Here we demonstrate that ocean pCO2 projected to occur by 2100 significantly effects the interactions of a predator-prey pair of common reef fish: the planktivorous damselfish Pomacentrus amboinensis and the piscivorous dottyback Pseudochromis fuscus. Prey exposed to elevated CO2 (880 µatm) or a present-day control (440 µatm) interacted with similarly exposed predators in a cross-factored design. Predators had the lowest capture success when exposed to elevated CO2 and interacting with prey exposed to present-day CO2. Prey exposed to elevated CO2 had reduced escape distances and longer reaction distances compared to prey exposed to present-day CO2 conditions, but this was dependent on whether the prey was paired with a CO2 exposed predator or not. This suggests that the dynamics of predator-prey interactions under future CO2 environments will depend on the extent to which the interacting species are affected and can adapt to the adverse effects of elevated CO2. PMID:23484032

  14. Effects of prey size and mobility on prey-capture kinematics in leopard sharks triakis semifasciata

    PubMed

    Ferry-Graham

    1998-08-01

    Recent work on teleosts suggests that attack behaviors or kinematics may be modified by a predator on the basis of the size of the prey or the ability of the prey to sense predators and escape capture (elusivity). Sharks are generally presumed to be highly visual predators; thus, it is reasonable to expect that they might also be capable of such behavioral modulation. In this study, I investigated the effect of prey item size and type on prey-capture behavior in leopard sharks (Triakis semifasciata) that had been acclimated to feeding in the laboratory. Using high-speed video, sharks were filmed feeding on two sizes of the same prey item (thawed shrimp pieces) and two potentially more elusive prey items (live earthworms and live mud shrimp). In leopard sharks, little effect of prey elusivity was found for kinematic variables during prey capture. However, the large proportion of successful captures of the live prey suggests that they did not prove to be truly elusive prey items for the leopard shark. There were significant size effects on prey-capture kinematics, with the larger non-elusive items inducing greater head expansion during prey capture. Ram-suction index values also indicated that strikes on large, non-elusive prey had a significantly larger suction component than strikes on similar small prey items. This finding is interesting given that the two sizes of non-elusive prey item offered no differential challenge in terms of a performance consequence (reduced capture success). PMID:9679105

  15. Prey items and predation behavior of killer whales (Orcinus orca) in Nunavut, Canada based on Inuit hunter interviews

    PubMed Central

    2012-01-01

    Background Killer whales (Orcinus orca) are the most widely distributed cetacean, occurring in all oceans worldwide, and within ocean regions different ecotypes are defined based on prey preferences. Prey items are largely unknown in the eastern Canadian Arctic and therefore we conducted a survey of Inuit Traditional Ecological Knowledge (TEK) to provide information on the feeding ecology of killer whales. We compiled Inuit observations on killer whales and their prey items via 105 semi-directed interviews conducted in 11 eastern Nunavut communities (Kivalliq and Qikiqtaaluk regions) from 2007-2010. Results Results detail local knowledge of killer whale prey items, hunting behaviour, prey responses, distribution of predation events, and prey capture techniques. Inuit TEK and published literature agree that killer whales at times eat only certain parts of prey, particularly of large whales, that attacks on large whales entail relatively small groups of killer whales, and that they hunt cooperatively. Inuit observations suggest that there is little prey specialization beyond marine mammals and there are no definitive observations of fish in the diet. Inuit hunters and elders also documented the use of sea ice and shallow water as prey refugia. Conclusions By combining TEK and scientific approaches we provide a more holistic view of killer whale predation in the eastern Canadian Arctic relevant to management and policy. Continuing the long-term relationship between scientists and hunters will provide for successful knowledge integration and has resulted in considerable improvement in understanding of killer whale ecology relevant to management of prey species. Combining scientists and Inuit knowledge will assist in northerners adapting to the restructuring of the Arctic marine ecosystem associated with warming and loss of sea ice. PMID:22520955

  16. Sexual Predators and Prey: A Comparative Study of the Hunting Behavior of Rapists and Child Molesters

    ERIC Educational Resources Information Center

    Rebocho, Maria Francisca; Goncalves, Rui Abrunhosa

    2012-01-01

    Although there has been an increase in research on sex offenders' modus operandi, geographic decision making, and hunting behavior, most studies still tend to emphasize criminal motivation while overlooking the role of situational and environmental factors. Studies of mixed samples of rapists and child molesters typically neglect to conduct…

  17. "Prey Play": Learning about Predators and Prey through an Interactive, Role-Play Game

    ERIC Educational Resources Information Center

    Deaton, Cynthia C. M.; Dodd, Kristen; Drennon, Katherine; Nagle, Jack

    2012-01-01

    "Prey Play" is an interactive role-play activity that provides fifth-grade students with opportunities to examine predator-prey interactions. This four-part, role-play activity allows students to take on the role of a predator and prey as they reflect on the behaviors animals exhibit as they collect food and interact with one another, as well as…

  18. Caring about Tomorrow: Future Orientation, Environmental Attitudes and Behaviors

    ERIC Educational Resources Information Center

    Carmi, Nurit

    2013-01-01

    Almost any pro-environmental behavior arouses a temporal conflict, as protecting long-term interests requires the sacrifice of short-term ones. Similarly, many health promoting behaviors may involve present discomfort for the sake of future well-being. In both contexts, health or environmental, developed future orientation (FO) is required to…

  19. Modification of a prey catching response and the development of behavioral persistence in the fire-bellied toad (Bombina orientalis).

    PubMed

    Ramsay, Zachary J; Ikura, Juntaro; Laberge, Frédéric

    2013-11-01

    The present report investigated how fire-bellied toads (Bombina orientalis) modified their response in a prey catching task in which the attribution of food reward was contingent on snapping toward a visual stimulus of moving prey displayed on a computer screen. Two experiments investigated modification of the snapping response, with different intervals between the opportunity to snap at the visual stimulus and reward administration. The snapping response of unpaired controls was decreased compared with the conditioned toads when hour or day intervals were used, but intervals of 5 min produced only minimal change in snapping. The determinants of extinction of the response toward the visual stimulus were then investigated in 3 experiments. The results of the first experiment suggested that increased resistance to extinction depended mostly on the number of training trials, not on partial reinforcement or the magnitude of reinforcement during training. This was confirmed in a second experiment showing that overtraining resulted in resistance to extinction, and that the pairing of the reward with a response toward the stimulus was necessary for that effect, as opposed to pairing reward solely with the experimental context. The last experiment showed that the time elapsed between training trials also influenced extinction, but only in toads that received few training trials. Overall, the results suggest that toads learning about a prey stimulus progress from an early flexible phase, when an action can be modified by its consequences, to an acquired habit characterized by an increasingly inflexible and automatic response. PMID:23668694

  20. The Coevolution of "Tyrannosaurus" & Its Prey: Could "Tyrannosaurus" Chase down & Kill a "Triceratops" for Lunch?

    ERIC Educational Resources Information Center

    May, S. Randolph

    2014-01-01

    Students will analyze the coevolution of the predator-prey relationships between "Tyrannosaurus rex" and its prey species using analyses of animal speeds from fossilized trackways, prey-animal armaments, adaptive behaviors, bite marks on prey-animal fossils, predator-prey ratios, and scavenger competition. The students will be asked to…

  1. Anticipating Their Future: Adolescent Values for the Future Predict Adult Behaviors

    ERIC Educational Resources Information Center

    Finlay, Andrea K.; Wray-Lake, Laura; Warren, Michael; Maggs, Jennifer

    2015-01-01

    Adolescent future values--beliefs about what will matter to them in the future--may shape their adult behavior. Utilizing a national longitudinal British sample, this study examined whether adolescent future values in six domains (i.e., family responsibility, full-time job, personal responsibility, autonomy, civic responsibility, and hedonistic…

  2. When Optimal Strategy Matters to Prey Fish

    PubMed Central

    Soto, Alberto; Stewart, William J.; McHenry, Matthew J.

    2015-01-01

    Predator–prey interactions are commonly studied with an interest in determining the optimal strategy for prey. However, the implications of deviating from optimal strategy are often unclear. The present study considered these consequences by studying how the direction of an escape response affects the strategy of prey fish. We simulated these interactions with numerical and analytical mathematics and compared our predictions with measurements in zebrafish larvae (Danio rerio), which are preyed upon by adults of the same species. Consistent with existing theory, we treated the minimum distance between predator and prey as the strategic payoff that prey aim to maximize. We found that these interactions may be characterized by three strategic domains that are defined by the speed of predator relative to the prey. The “fast predator” domain occurs when the predator is more than an order of magnitude faster than the prey. The escape direction of the prey had only a small effect on the minimum distance under these conditions. For the “slow predator” domain, when the prey is faster than the predator, we found that differences in direction had no effect on the minimum distance for a broad range of escape angles. This was the regime in which zebrafish were found to operate. In contrast, the optimal escape angle offers a large benefit to the minimum distance in the intermediate strategic domain. Therefore, optimal strategy is most meaningful to prey fish when predators are faster than prey by less than a factor of 10. This demonstrates that the strategy of a prey animal does not matter under certain conditions that are created by the behavior of the predator. PMID:25964496

  3. Charismatic Behaviors and Traits of Future Educational Leaders.

    ERIC Educational Resources Information Center

    Serafin, Ana Gil

    This paper examines the charismatic behaviors and traits entering graduate students bring to their training as future educational leaders and explores the differences in gender, age, marital status, position held, and sibling ranks of entering graduate students regarding charismatic behaviors and traits. The exploratory descriptive study examined…

  4. Chemotactic predator-prey dynamics.

    PubMed

    Sengupta, Ankush; Kruppa, Tobias; Löwen, Hartmut

    2011-03-01

    A discrete chemotactic predator-prey model is proposed in which the prey secrets a diffusing chemical which is sensed by the predator and vice versa. Two dynamical states corresponding to catching and escaping are identified and it is shown that steady hunting is unstable. For the escape process, the predator-prey distance is diffusive for short times but exhibits a transient subdiffusive behavior which scales as a power law t¹/³ with time t and ultimately crosses over to diffusion again. This allows us to classify the motility and dynamics of various predatory microbes and phagocytes. In particular, there is a distinct region in the parameter space where they prove to be infallible predators. PMID:21517532

  5. Forming Attitudes that Predict Future Behavior: A Meta-Analysis of the Attitude-Behavior Relation

    ERIC Educational Resources Information Center

    Glasman, Laura R.; Albarracin, Dolores

    2006-01-01

    A meta-analysis (k of conditions = 128; N = 4,598) examined the influence of factors present at the time an attitude is formed on the degree to which this attitude guides future behavior. The findings indicated that attitudes correlated with a future behavior more strongly when they were easy to recall (accessible) and stable over time. Because of…

  6. A Historical Perspective on the Future of Behavior Science.

    PubMed

    Hayes, Linda J; Fryling, Mitch J

    2015-10-01

    Like all natural sciences, behavior science has much to offer toward an understanding of the world. The extent to which the promise of behavior science is realized, though, depends upon the extent to which we keep what we know before us. This paper considers fundamental concepts in behavior science, including the concepts of behavior, stimulation, setting conditions, and language. In considering these concepts, we revisit comments from B. F. Skinner and J. R. Kantor and also consider some areas of behavior analytic research and the implications they have for reconsidering long-held assumptions about the analysis of behavior. We hope that, in considering our foundations, the vitality and strength of the discipline might be enhanced, our impact on science improved, and our future secured. PMID:27606169

  7. Behavioral health and disasters: looking to the future.

    PubMed

    Palinkas, Lawrence A

    2015-01-01

    Along with other manmade and natural disasters, oil spills produce profound and long-term impacts on the behavioral health of their survivors. Although previous and ongoing research has focused on producing evidence of the breadth and depth of these impacts, future efforts must begin to translate this evidence into developing and implementing policies, programs, and practices that effectively contribute to their prevention and mitigation. Drawing upon a conceptual framework of the behavioral health impacts of oil spills developed from data collected in the aftermath of the Exxon Valdez oil spill in 1989, this paper examines potential interventions designed to prevent or mitigate biopsychosocial, interpersonal, and intrapersonal impacts on behavioral health. Future efforts to translate behavioral health research into effective practice will require the formation and maintenance of academic-community partnerships for the purpose of building resilience to these impacts and providing targeted services to those most vulnerable to their long-term consequences. PMID:24443145

  8. Behavioral Health and Disasters: Looking to the Future

    PubMed Central

    Palinkas, Lawrence A.

    2014-01-01

    Along with other manmade and natural disasters, oil spills produce profound and long-term impacts on the behavioral health of their survivors. While previous and ongoing research has focused on producing evidence of the breadth and depth of these impacts, future efforts must begin to translate this evidence into developing and implementing policies, programs and practices that effectively contribute to their prevention and mitigation. Drawing upon a conceptual framework of the behavioral health impacts of oil spills developed from data collected in the aftermath of the Exxon Valdez oil spill in 1989, this paper examines potential interventions designed to prevent or mitigate biopsychosocial, interpersonal and intrapersonal impacts on behavioral health. Future efforts to translate behavioral health research into effective practice will require the formation and maintenance of academic-community partnerships for the purpose of building resilience to these impacts and providing targeted services to those most vulnerable to their long-term consequences. PMID:24443145

  9. Predictions of Future Daily Behaviors: A Further Replication.

    ERIC Educational Resources Information Center

    Bull, C. Neil

    The present study is a continuation of a series of studies dealing with predictions of future daily behaviors. Because of the finite nature of time, people have to make choices among activities, bearing in mind the duration of such activities. The dimension of "discretion", which deals specifically with the duration of time a person spends on an…

  10. Looking to the Future: Will Behavior Analysis Survive and Prosper?

    ERIC Educational Resources Information Center

    Poling, Alan

    2010-01-01

    Behavior analysis as a discipline currently is doing relatively well. How it will do in the future is unclear and depends on how the field, and the world at large, changes. Five current characteristics of the discipline that appear to reduce the probability that it will survive and prosper are discussed and suggestions for improvement are offered.…

  11. Future Orientation, School Contexts, and Problem Behaviors: A Multilevel Study

    ERIC Educational Resources Information Center

    Chen, Pan; Vazsonyi, Alexander T.

    2013-01-01

    The association between future orientation and problem behaviors has received extensive empirical attention; however, previous work has not considered school contextual influences on this link. Using a sample of N = 9,163 9th to 12th graders (51.0% females) from N = 85 high schools of the National Longitudinal Study of Adolescent Health, the…

  12. Clinician Perceptions of Childhood Risk Factors for Future Antisocial Behavior

    ERIC Educational Resources Information Center

    Koegl, Christopher J.; Farrington, David P.; Augimeri, Leena K.

    2009-01-01

    We asked 176 mental health clinicians to list factors that place a child at risk for engaging in future antisocial behavior. Participants were randomly assigned to do this in relationship to boys and girls. Listed factors were then coded into broad item categories using the Early Assessment Risk Lists (EARL). Of the 1,695 factors listed, 1,476…

  13. Hispanic Behavioral Science Research: Recommendations for Future Research.

    ERIC Educational Resources Information Center

    Padilla, Amado M.; Lindholm, Kathryn J.

    1984-01-01

    Presents major developments in Hispanic behavioral science research over the past decade, and provides recommendations for future research, organized into three broad categories: life span issues (childhood, adolescence, adulthood, and elderly, all including some education-related issues), delivery of mental health services, and prevention and…

  14. Materialism, Stress and Health Behaviors among Future Educators

    ERIC Educational Resources Information Center

    Brouskeli, Vasiliki; Loumakou, Maria

    2014-01-01

    In this study we investigated materialism among future educators and its relationship with stress and a number of health behaviors. Participants were 228 students (Mean = 20.64 years of age, S.D = 2.571) of the Department of Education Sciences in Early Childhood of the University of Thrace, Greece. The instrument consisted of a short form of the…

  15. Neural circuits underlying tongue movements for the prey-catching behavior in frog: distribution of primary afferent terminals on motoneurons supplying the tongue.

    PubMed

    Kecskes, Szilvia; Matesz, Clara; Gaál, Botond; Birinyi, András

    2016-04-01

    The hypoglossal motor nucleus is one of the efferent components of the neural network underlying the tongue prehension behavior of Ranid frogs. Although the appropriate pattern of the motor activity is determined by motor pattern generators, sensory inputs can modify the ongoing motor execution. Combination of fluorescent tracers were applied to investigate whether there are direct contacts between the afferent fibers of the trigeminal, facial, vestibular, glossopharyngeal-vagal, hypoglossal, second cervical spinal nerves and the hypoglossal motoneurons. Using confocal laser scanning microscope, we detected different number of close contacts from various sensory fibers, which were distributed unequally between the motoneurons innervating the protractor, retractor and inner muscles of the tongue. Based on the highest number of contacts and their closest location to the perikaryon, the glossopharyngeal-vagal nerves can exert the strongest effect on hypoglossal motoneurons and in agreement with earlier physiological results, they influence the protraction of the tongue. The second largest number of close appositions was provided by the hypoglossal and second cervical spinal afferents and they were located mostly on the proximal and middle parts of the dendrites of retractor motoneurons. Due to their small number and distal location, the trigeminal and vestibular terminals seem to have minor effects on direct activation of the hypoglossal motoneurons. We concluded that direct contacts between primary afferent terminals and hypoglossal motoneurons provide one of the possible morphological substrates of very quick feedback and feedforward modulation of the motor program during various stages of prey-catching behavior. PMID:25575900

  16. Interspecific variation in prey capture behavior by co-occurring Nepenthes pitcher plants: evidence for resource partitioning or sampling-scheme artifacts?

    PubMed

    Chin, Lijin; Chung, Arthur Y C; Clarke, Charles

    2014-01-01

    Pitcher plants of the genus Nepenthes capture a wide range of arthropod prey for nutritional benefit, using complex combinations of visual and olfactory signals and gravity-driven pitfall trapping mechanisms. In many localities throughout Southeast Asia, several Nepenthes different species occur in mixed populations. Often, the species present at any given location have strongly divergent trap structures and preliminary surveys indicate that different species trap different combinations of arthropod prey, even when growing at the same locality. On this basis, it has been proposed that co-existing Nepenthes species may be engaged in niche segregation with regards to arthropod prey, avoiding direct competition with congeners by deploying traps that have modifications that enable them to target specific prey types. We examined prey capture among 3 multi-species Nepenthes populations in Borneo, finding that co-existing Nepenthes species do capture different combinations of prey, but that significant interspecific variations in arthropod prey combinations can often be detected only at sub-ordinal taxonomic ranks. In all lowland Nepenthes species examined, the dominant prey taxon is Formicidae, but montane Nepenthes trap few (or no) ants and 2 of the 3 species studied have evolved to target alternative sources of nutrition, such as tree shrew feces. Using similarity and null model analyses, we detected evidence for niche segregation with regards to formicid prey among 5 lowland, sympatric Nepenthes species in Sarawak. However, we were unable to determine whether these results provide support for the niche segregation hypothesis, or whether they simply reflect unquantified variation in heterogeneous habitats and/or ant communities in the study sites. These findings are used to propose improvements to the design of field experiments that seek to test hypotheses about targeted prey capture patterns in Nepenthes. PMID:24481246

  17. Forming Attitudes That Predict Future Behavior: A Meta-Analysis of the Attitude–Behavior Relation

    PubMed Central

    Glasman, Laura R.; Albarracín, Dolores

    2016-01-01

    A meta-analysis (k of conditions = 128; N = 4,598) examined the influence of factors present at the time an attitude is formed on the degree to which this attitude guides future behavior. The findings indicated that attitudes correlated with a future behavior more strongly when they were easy to recall (accessible) and stable over time. Because of increased accessibility, attitudes more strongly predicted future behavior when participants had direct experience with the attitude object and reported their attitudes frequently. Because of the resulting attitude stability, the attitude–behavior association was strongest when attitudes were confident, when participants formed their attitude on the basis of behavior-relevant information, and when they received or were induced to think about one- rather than two-sided information about the attitude object. PMID:16910754

  18. Effects of the prey refuge distribution on a predator-prey system

    NASA Astrophysics Data System (ADS)

    Lee, Sang-Hee; Kwon, Ohsung; Song, Hark-Soo

    2016-03-01

    The existence of prey refuges in a predator-prey system is known to be strongly related to the ecosystem's stability. In this study, we explored how the prey refuge distribution affects the predator-prey system. To do so, we constructed a spatial lattice model to simulate an integrative predator (wolf) - prey (rabbit) - plant (grass) relationship. When a wolf (rabbit) encountered a rabbit (grass), the wolf (rabbit) tended to move to the rabbit (grass) for foraging while the rabbit tended to escape from the wolf. These behaviors were mathematically described by the degrees of willingness for hunting ( H) and escaping ( E). Initially, n refuges for prey were heterogeneously distributed in the lattice space. The heterogeneity was characterized as variable A. Higher values of A equate to higher aggregation in the refuge. We investigated the mean population density for different values of H, E, and A. To simply characterize the refuge distribution effect, we built an H-E grid map containing the population density for each species. Then, we counted the number of grids, N, with a population density ≥ 0.25. Simulation results showed that an appropriate value of A positively affected prey survival while values of A were too high had a negative effect on prey survival. The results were explained by using the trade-off between the staying time of the prey in the refuge and the cluster size of the refuge.

  19. Predicting Premeditation: Future Behavior Is Seen as More Intentional than Past Behavior

    ERIC Educational Resources Information Center

    Burns, Zachary C.; Caruso, Eugene M.; Bartels, Daniel M.

    2012-01-01

    People's intuitions about the underlying causes of past and future actions might not be the same. In 3 studies, we demonstrate that people judge the same behavior as more intentional when it will be performed in the future than when it has been performed in the past. We found this temporal asymmetry in perceptions of both the strength of an…

  20. Predator prey interactions of Procambarus clarkii with aquatic macroinvertebrates in single and multiple prey systems

    NASA Astrophysics Data System (ADS)

    Correia, Alexandra Marçal; Bandeira, Nuno; Anastácio, Pedro Manuel

    2005-11-01

    Understanding the interspecific interactions of Procambarus clarkii with other aquatic macroinvertebrates will help to unveil the mechanisms and processes underlying biological invasiveness. The purpose of this study was to investigate predator-prey interactions of two ontogenic phases of P. clarkii with native and exotic species of aquatic macroinvertebrates at a single and multiple prey level. We performed laboratory experiments to determine the consumption and the behavioral responses of Chironomus riparius, Physa acuta and Corbicula fluminea to P. clarkii. The presence of P. clarkii significantly affected the abundance of C. riparius and P. acuta, but not of C. fluminea whether prey species were provided singly or simultaneously. The consumption of C. riparius by P. clarkii was higher than P. acuta for both crayfish sizes and situations (single/multiple prey systems) and C. fluminea was never consumed. Physa acuta was the only species that exhibited an anti-predator behavior to P. clarkii. Our results show that P. clarkii can have strong consumptive and trait effects on aquatic macroinvertebrate prey at a single and multiple prey level, resulting in differential impacts on different prey species. This study clarifies some aspects of the predator-prey interactions between P. clarkii and native as well as other exotic macroinvertebrate species that have invaded freshwater biocenosis worldwide.

  1. Stabilization of perceived echo amplitudes in echolocating bats. II. The acoustic behavior of the big brown bat, Eptesicus fuscus, when tracking moving prey.

    PubMed

    Hartley, D J

    1992-02-01

    Big brown bats, Eptesicus fuscus, can be trained to use echolocation to track a small microphone with a food reward attached when it is moved rapidly toward them. This situation mimics prey interception in the wild while allowing very precise recording of the sonar pulses emitted during tracking behavior. The results show that E. fuscus intensity compensates, reducing emitted intensity by 6 dB per halving of target range so that the intensity incident upon the target is constant and echo intensity increases by 6 dB per halving of range. This increase in echo intensity is effectively canceled by the reduction in auditory sensitivity due to automatic gain control (AGC) of 6 to 7 dB per halving of range. Intensity compensation behavior and AGC therefore form a dual-component, symmetrical system that stabilizes perceived echo amplitudes during target approach. The same system is present in the fishing bat, Noctilio leporinus, suggesting that it may be widespread in echolocating bats. Correlation analysis shows that, despite large changes in the duration of the pulses emitted by E. fuscus during an approach, the pulse frequency structure is such that the spatial image of the target perceived along the range axis is highly stable. Pulse duration is not reduced in the manner theoretically necessary to eliminate potential echo distortion effects due to AGC, but is reduced in such a way that this distortion is insignificant. During the terminal buzz, a high degree of temporal overlap (relative to pulse duration) occurs between emitted pulse and returning echo. PMID:1556313

  2. Personality traits, future time perspective and adaptive behavior in adolescence.

    PubMed

    Gomes Carvalho, Renato Gil; Novo, Rosa Ferreira

    2015-01-01

    Several studies provide evidence of the importance of future time perspective (FTP) for individual success. However, little research addresses the relationship between FTP and personality traits, particularly if FTP can mediate their influence on behavior. In this study we analyze the mediating of FTP in the influence of personality traits on the way adolescents live their life at school. Sample consisted in 351 students, aged from 14 to 18 years-old, at different schooling levels. Instruments were the Portuguese version of the MMPI-A, particularly the PSY-5 dimensions (Aggressiveness, Psychoticism, Disconstraint, Neuroticism, Introversion), a FTP questionnaire, and a survey on school life, involving several indicators of achievement, social integration, and overall satisfaction. With the exception of Neuroticism, the results show significant mediation effects (p < .001) of FTP on most relationships between PSY-5 dimensions and school life variables. Concerning Disconstraint, FTP mediated its influence on overall satisfaction (β = -.125) and school achievement (β = -.106). In the case of Introversion, significant mediation effects occurred for interpersonal difficulties (β = .099) and participation in extracurricular activities (β = -.085). FTP was also a mediator of Psychoticism influence in overall satisfaction (β = -.094), interpersonal difficulties (β = .057), and behavior problems (β = .037). Finally, FTP mediated the influence of Aggressiveness on overall satisfaction (β = -.061), interpersonal difficulties (β = .040), achievement (β = -.052), and behavior problems (β = .023). Results are discussed considering the importance of FTP in the impact of some personality structural characteristics in students' school adaptation. PMID:25907852

  3. Prey selection by the Lake Superior fish community

    USGS Publications Warehouse

    Isaac, Edmund J.; Hrabik, Thomas R.; Stockwell, Jason D.; Gamble, Allison E.

    2012-01-01

    Mysis diluviana is an important prey item to the Lake Superior fish community as found through a recent diet study. We further evaluated this by relating the quantity of prey found in fish diets to the quantity of prey available to fish, providing insight into feeding behavior and prey preferences. We describe the seasonal prey selection of major fish species collected across 18 stations in Lake Superior in spring, summer, and fall of 2005. Of the major nearshore fish species, bloater (Coregonus hoyi), rainbow smelt (Osmerus mordax), and lake whitefish (Coregonus clupeaformis) consumed Mysis, and strongly selected Mysis over other prey items each season. However, lake whitefish also selected Bythotrephes in the fall when Bythotrephes were numerous. Cisco (Coregonus artedi), a major nearshore and offshore species, fed largely on calanoid copepods, and selected calanoid copepods (spring) and Bythotrephes (summer and fall). Cisco also targeted prey similarly across bathymetric depths. Other major offshore fish species such as kiyi (Coregonus kiyi) and deepwater sculpin (Myoxocephalus thompsoni) fed largely on Mysis, with kiyi targeting Mysis exclusively while deepwater sculpin did not prefer any single prey organism. The major offshore predator siscowet lake trout (Salvelinus namaycush siscowet) consumed deepwater sculpin and coregonines, but selected deepwater sculpin and Mysis each season, with juveniles having a higher selection for Mysis than adults. Our results suggest that Mysis is not only a commonly consumed prey item, but a highly preferred prey item for pelagic, benthic, and piscivorous fishes in nearshore and offshore waters of Lake Superior.

  4. When values matter: Expressing values in behavioral intentions for the near vs. distant future

    PubMed Central

    Eyal, Tal; Sagristano, Michael D.; Trope, Yaacov; Liberman, Nira; Chaiken, Shelly

    2011-01-01

    It was predicted that because of their abstract nature, values will have greater impact on how individuals plan their distant future than their near future. Experiments 1 and 2 found that values better predict behavioral intentions for distant future situations than near future situations. Experiment 3 found that whereas high-level values predict behavioral intentions for more distant future situations, low-level feasibility considerations predict behavioral intentions for more proximate situation. Finally, Experiment 4 found that the temporal changes in the relationship between values and behavioral intentions depended on how the behavior was construed. Higher correspondence is found when behaviors are construed on a higher level and when behavior is planned for the more distant future than when the same behavior is construed on a lower level or is planned for the more proximal future. The implications of these findings for self-consistency and value conflicts are discussed. PMID:21822329

  5. A dedicated visual pathway for prey detection in larval zebrafish.

    PubMed

    Semmelhack, Julia L; Donovan, Joseph C; Thiele, Tod R; Kuehn, Enrico; Laurell, Eva; Baier, Herwig

    2014-01-01

    Zebrafish larvae show characteristic prey capture behavior in response to small moving objects. The neural mechanism used to recognize objects as prey remains largely unknown. We devised a machine learning behavior classification system to quantify hunting kinematics in semi-restrained animals exposed to a range of virtual stimuli. Two-photon calcium imaging revealed a small visual area, AF7, that was activated specifically by the optimal prey stimulus. This pretectal region is innervated by two types of retinal ganglion cells, which also send collaterals to the optic tectum. Laser ablation of AF7 markedly reduced prey capture behavior. We identified neurons with arbors in AF7 and found that they projected to multiple sensory and premotor areas: the optic tectum, the nucleus of the medial longitudinal fasciculus (nMLF) and the hindbrain. These findings indicate that computations in the retina give rise to a visual stream which transforms sensory information into a directed prey capture response. PMID:25490154

  6. Cognitive behavioral therapy: current status and future research directions.

    PubMed

    McMain, Shelley; Newman, Michelle G; Segal, Zindel V; DeRubeis, Robert J

    2015-01-01

    Cognitive behavioral therapy (CBT), an umbrella term that includes a diverse group of treatments, is defined by a strong commitment to empiricism. While CBT has a robust empirical base, areas for improvement remain. This article reviews the status of the current empirical base and its limitations, and presents future directions for advancement of the field. Ultimately, studies are needed that will identify the predictors, mediators, and moderators of treatment response in order to increase knowledge on how to personalize interventions for each client and to strengthen the impact of CBT. Efforts to advance the dissemination and implementation of CBT, innovative approaches such as practice-oriented research, and the advantages of incorporating new and existing technologies, are discussed as well. PMID:25689506

  7. Health behaviors among college students: the influence of future time perspective and basic psychological need satisfaction

    PubMed Central

    Visser, Preston L.; Hirsch, Jameson K.

    2014-01-01

    Health behavior change may prevent many fatal diseases, and may be influenced by social and motivational constructs. We assessed the interaction effect of future time perspective and basic psychological need fulfillment on positive and negative health behaviors. Future time perspective was associated with more positive, and less negative, health behaviors. Need fulfillment was associated with only positive health behaviors. In moderation analyses, individuals reporting both high need fulfillment and future perspective reported greater positive health behaviors, and were especially unlikely to smoke. Enhancing future-mindedness and supporting need satisfaction in interventions targeting modifiable health behaviors is encouraged. PMID:25750770

  8. L-shaped prey isocline in the Gause predator-prey experiments with a prey refuge.

    PubMed

    Křivan, Vlastimil; Priyadarshi, Anupam

    2015-04-01

    Predator and prey isoclines are estimated from data on yeast-protist population dynamics (Gause et al., 1936). Regression analysis shows that the prey isocline is best fitted by an L-shaped function that has a vertical and a horizontal part. The predator isocline is vertical. This shape of isoclines corresponds with the Lotka-Volterra and the Rosenzweig-MacArthur predator-prey models that assume a prey refuge. These results further support the idea that a prey refuge changes the prey isocline of predator-prey models from a horizontal to an L-shaped curve. Such a shape of the prey isocline effectively bounds amplitude of predator-prey oscillations, thus promotes species coexistence. PMID:25644756

  9. The Diel Rhythms of Biosonar Behavior in the Yangtze Finless Porpoise (Neophocaena asiaeorientalis asiaeorientalis) in the Port of the Yangtze River: The Correlation between Prey Availability and Boat Traffic

    PubMed Central

    Wang, Zhitao; Akamatsu, Tomonari; Wang, Kexiong; Wang, Ding

    2014-01-01

    Information on the habitat use of the critically endangered Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) is critical for its conservation. The diel biosonar behavior of the porpoise in the port areas of the Yangtze River was examined along with simultaneous observations of fish density and boat traffic. Biosonar pulses from the porpoises were detected for 1233 min (5.77%) over a 21,380 min duration of effective observations. In total, 190 (5.63%) buzzes (an indication of prey capture attempts) were recorded among the 3372 identified click trains. Of the 168 echolocation encounters (bouts of click trains less than eight min apart), 150 (89.3%) involved single animals, indicating that solitary porpoises were frequently present and feeding in the port areas. Significant diel patterns were evident involving the biosonar behavior of the porpoises (including click trains and buzzes), fish density and boat traffic. The frequencies of the click trains and buzzes were significantly lower during the day than in the evening and at night, which suggests that porpoises in this region are primarily engaged in crepuscular and nocturnal foraging. The lack of a significant diel pattern in the echolocation encounters indicates the importance of the port in porpoise conservation. A forced feeding schedule may be associated with the lack of a significant correlation between porpoise acoustics and boat traffic. Overall, prey availability appears to be the primary factor that attracts porpoises. Additionally, porpoises tend to migrate or remain downstream in the morning and migrate or remain upstream in the evening, most likely to follow their prey. The findings of this study can be used to improve the conservation of the Yangtze finless porpoise. PMID:24823945

  10. The diel rhythms of biosonar behavior in the Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) in the port of the Yangtze River: The correlation between prey availability and boat traffic.

    PubMed

    Wang, Zhitao; Akamatsu, Tomonari; Wang, Kexiong; Wang, Ding

    2014-01-01

    Information on the habitat use of the critically endangered Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) is critical for its conservation. The diel biosonar behavior of the porpoise in the port areas of the Yangtze River was examined along with simultaneous observations of fish density and boat traffic. Biosonar pulses from the porpoises were detected for 1233 min (5.77%) over a 21,380 min duration of effective observations. In total, 190 (5.63%) buzzes (an indication of prey capture attempts) were recorded among the 3372 identified click trains. Of the 168 echolocation encounters (bouts of click trains less than eight min apart), 150 (89.3%) involved single animals, indicating that solitary porpoises were frequently present and feeding in the port areas. Significant diel patterns were evident involving the biosonar behavior of the porpoises (including click trains and buzzes), fish density and boat traffic. The frequencies of the click trains and buzzes were significantly lower during the day than in the evening and at night, which suggests that porpoises in this region are primarily engaged in crepuscular and nocturnal foraging. The lack of a significant diel pattern in the echolocation encounters indicates the importance of the port in porpoise conservation. A forced feeding schedule may be associated with the lack of a significant correlation between porpoise acoustics and boat traffic. Overall, prey availability appears to be the primary factor that attracts porpoises. Additionally, porpoises tend to migrate or remain downstream in the morning and migrate or remain upstream in the evening, most likely to follow their prey. The findings of this study can be used to improve the conservation of the Yangtze finless porpoise. PMID:24823945

  11. Sequential assessment of prey through the use of multiple sensory cues by an eavesdropping bat

    NASA Astrophysics Data System (ADS)

    Page, Rachel A.; Schnelle, Tanja; Kalko, Elisabeth K. V.; Bunge, Thomas; Bernal, Ximena E.

    2012-06-01

    Predators are often confronted with a broad diversity of potential prey. They rely on cues associated with prey quality and palatability to optimize their hunting success and to avoid consuming toxic prey. Here, we investigate a predator's ability to assess prey cues during capture, handling, and consumption when confronted with conflicting information about prey quality. We used advertisement calls of a preferred prey item (the túngara frog) to attract fringe-lipped bats, Trachops cirrhosus, then offered palatable, poisonous, and chemically manipulated anurans as prey. Advertisement calls elicited an attack response, but as bats approached, they used additional sensory cues in a sequential manner to update their information about prey size and palatability. While both palatable and poisonous small anurans were readily captured, large poisonous toads were approached but not contacted suggesting the use of echolocation for assessment of prey size at close range. Once prey was captured, bats used chemical cues to make final, post-capture decisions about whether to consume the prey. Bats dropped small, poisonous toads as well as palatable frogs coated in toad toxins either immediately or shortly after capture. Our study suggests that echolocation and chemical cues obtained at close range supplement information obtained from acoustic cues at long range. Updating information about prey quality minimizes the occurrence of costly errors and may be advantageous in tracking temporal and spatial fluctuations of prey and exploiting novel food sources. These findings emphasize the sequential, complex nature of prey assessment that may allow exploratory and flexible hunting behaviors.

  12. Electric Eels Concentrate Their Electric Field to Induce Involuntary Fatigue in Struggling Prey.

    PubMed

    Catania, Kenneth C

    2015-11-16

    Nature is replete with predator venoms that immobilize prey by targeting ion channels. Electric eels (Electrophorus electricus) take a different tactic to accomplish the same end. Striking eels emit electricity in volleys of 1 ms, high-voltage pulses. Each pulse is capable of activating prey motor neuron efferents, and hence muscles. In a typical attack, eel discharges cause brief, immobilizing tetanus, allowing eels to swallow small prey almost immediately. Here I show that when eels struggle with large prey or fish held precariously, they commonly curl to bring their own tail to the opposite side of prey, sandwiching it between the two poles of their powerful electric organ. They then deliver volleys of high-voltage pulses. Shortly thereafter, eels juggle prey into a favorable position for swallowing. Recordings from electrodes placed within prey items show that this curling behavior at least doubles the field strength within shocked prey, most likely ensuring reliable activation of the majority of prey motor neurons. Simulated pulse trains, or pulses from an eel-triggered stimulator, applied to a prey muscle preparations result in profound muscle fatigue and loss of contractile force. Consistent with this result, video recordings show that formerly struggling prey are temporarily immobile after this form of attack, allowing the manipulation of prey that might otherwise escape. These results reveal a unique use of electric organs to a unique end; eels superimpose electric fields from two poles, ensuring maximal remote activation of prey efferents that blocks subsequent prey movement by inducing involuntary muscle fatigue. PMID:26521183

  13. Sequential assessment of prey through the use of multiple sensory cues by an eavesdropping bat.

    PubMed

    Page, Rachel A; Schnelle, Tanja; Kalko, Elisabeth K V; Bunge, Thomas; Bernal, Ximena E

    2012-06-01

    Predators are often confronted with a broad diversity of potential prey. They rely on cues associated with prey quality and palatability to optimize their hunting success and to avoid consuming toxic prey. Here, we investigate a predator's ability to assess prey cues during capture, handling, and consumption when confronted with conflicting information about prey quality. We used advertisement calls of a preferred prey item (the túngara frog) to attract fringe-lipped bats, Trachops cirrhosus, then offered palatable, poisonous, and chemically manipulated anurans as prey. Advertisement calls elicited an attack response, but as bats approached, they used additional sensory cues in a sequential manner to update their information about prey size and palatability. While both palatable and poisonous small anurans were readily captured, large poisonous toads were approached but not contacted suggesting the use of echolocation for assessment of prey size at close range. Once prey was captured, bats used chemical cues to make final, post-capture decisions about whether to consume the prey. Bats dropped small, poisonous toads as well as palatable frogs coated in toad toxins either immediately or shortly after capture. Our study suggests that echolocation and chemical cues obtained at close range supplement information obtained from acoustic cues at long range. Updating information about prey quality minimizes the occurrence of costly errors and may be advantageous in tracking temporal and spatial fluctuations of prey and exploiting novel food sources. These findings emphasize the sequential, complex nature of prey assessment that may allow exploratory and flexible hunting behaviors. PMID:22592417

  14. Behavior analysis: thriving, but how about its future?

    PubMed

    Fantino, Edmund

    2008-01-01

    Behavior analysis has been thriving by continuing to make important theoretical and empirical contributions to a wide array of problems, as well as by contributing to interdisciplinary research. Applied research in behavior analysis is flourishing. Despite these positive signs there may be an erosion of support for basic research in animal learning and behavior, including behavior analysis. Increased attention by behavior analysts to fundamental problems in areas of cognition, including decision-making and language, may help behavior analysis to evolve more successfully. An experimental analysis of gambling may prove particularly fruitful. PMID:18338680

  15. Restricting Prey Dispersal Can Overestimate the Importance of Predation in Trophic Cascades

    PubMed Central

    Geraldi, Nathan R.; Macreadie, Peter I.

    2013-01-01

    Predators can affect prey populations and, via trophic cascades, predators can indirectly impact resource populations (2 trophic levels below the predator) through consumption of prey (density-mediated indirect effects; DMIEs) and by inducing predator-avoidance behavior in prey (trait-mediated indirect effects; TMIEs). Prey often employ multiple predator-avoidance behaviors, such as dispersal or reduced foraging activity, but estimates of TMIEs are usually on individual behaviors. We assessed direct and indirect predator effects in a mesocosm experiment using a marine food chain consisting of a predator (toadfish – Opsanus tau), prey (mud crab - Panopeus herbstii) and resource (ribbed mussel – Geukensia demissa). We measured dispersal and foraging activity of prey separately by manipulating both the presence and absence of the predator, and whether prey could or could not disperse into a predator-free area. Consumption of prey was 9 times greater when prey could not disperse, probably because mesocosm boundaries increased predator capture success. Although predator presence did not significantly affect the number of crabs that emigrated, the presence of a predator decreased resource consumption by prey, which resulted in fewer resources consumed for each prey that emigrated in the presence of a predator, and reduced the overall TMIE. When prey were unable to disperse, TMIEs on mussel survival were 3 times higher than the DMIEs. When prey were allowed to disperse, the TMIEs on resource survival increased to 11-times the DMIEs. We found that restricting the ability of prey to disperse, or focusing on only one predator-avoidance behavior, may be underestimating TMIEs. Our results indicate that the relative contribution of behavior and consumption in food chain dynamics will depend on which predator-avoidance behaviors are allowed to occur and measured. PMID:23408957

  16. Functional Behavior Assessment in Schools: Current Status and Future Directions

    ERIC Educational Resources Information Center

    Anderson, Cynthia M.; Rodriguez, Billie Jo; Campbell, Amy

    2015-01-01

    Functional behavior assessment is becoming a commonly used practice in school settings. Accompanying this growth has been an increase in research on functional behavior assessment. We reviewed the extant literature on documenting indirect and direct methods of functional behavior assessment in school settings. To discern best practice guidelines…

  17. Experimental determination of the spatial scale of a prey patch from the predator's perspective.

    PubMed

    Birk, Matthew A; White, J Wilson

    2014-03-01

    Foraging theory predicts that predators should prefer foraging in habitat patches with higher prey densities. However, density depends on the spatial scale at which a "patch" is defined by an observer. Ecologists strive to measure prey densities at the same scale that predators do, but many natural landscapes lack obvious, well-defined prey patches. Thus one must determine the scale at which predators define patches of prey. We estimated the scale at which guppies, Poecilia reticulata, selected patches of zooplankton prey using a behavioral assay. Guppies could choose between two prey arrays, each manipulated to have a density that depended on the spatial scale at which density was calculated. We estimated the scale of guppy foraging by comparing guppy preferences across a series of trials in which we systematically varied the scale associated with "high" prey density. This approach enables the application of foraging theory to non-discrete habitats and prey landscapes. PMID:24241641

  18. The Allometry of Prey Preferences

    PubMed Central

    Kalinkat, Gregor; Rall, Björn Christian; Vucic-Pestic, Olivera; Brose, Ulrich

    2011-01-01

    The distribution of weak and strong non-linear feeding interactions (i.e., functional responses) across the links of complex food webs is critically important for their stability. While empirical advances have unravelled constraints on single-prey functional responses, their validity in the context of complex food webs where most predators have multiple prey remain uncertain. In this study, we present conceptual evidence for the invalidity of strictly density-dependent consumption as the null model in multi-prey experiments. Instead, we employ two-prey functional responses parameterised with allometric scaling relationships of the functional response parameters that were derived from a previous single-prey functional response study as novel null models. Our experiments included predators of different sizes from two taxonomical groups (wolf spiders and ground beetles) simultaneously preying on one small and one large prey species. We define compliance with the null model predictions (based on two independent single-prey functional responses) as passive preferences or passive switching, and deviations from the null model as active preferences or active switching. Our results indicate active and passive preferences for the larger prey by predators that are at least twice the size of the larger prey. Moreover, our approach revealed that active preferences increased significantly with the predator-prey body-mass ratio. Together with prior allometric scaling relationships of functional response parameters, this preference allometry may allow estimating the distribution of functional response parameters across the myriads of interactions in natural ecosystems. PMID:21998724

  19. Indirect effects of primary prey population dynamics on alternative prey.

    PubMed

    Barraquand, Frédéric; New, Leslie F; Redpath, Stephen; Matthiopoulos, Jason

    2015-08-01

    We develop a theory of generalist predation showing how alternative prey species are affected by changes in both mean abundance and variability (coefficient of variation) of their predator's primary prey. The theory is motivated by the indirect effects of cyclic rodent populations on ground-breeding birds, and developed through progressive analytic simplifications of an empirically-based model. It applies nonetheless to many other systems where primary prey have fast life-histories and can become superabundant, thus facilitating impact on alternative prey species and generating highly asymmetric interactions. Our results suggest that predator effects on alternative prey should generally decrease with mean primary prey abundance, and increase with primary prey variability (low to high CV)-unless predators have strong aggregative responses, in which case these results can be reversed. Approximations of models including predator dynamics (general numerical response with possible delays) confirm these results but further suggest that negative temporal correlation between predator and primary prey is harmful to alternative prey. Finally, we find that measurements of predator numerical responses are crucial to predict-even qualitatively-the response of ecosystems to changes in the dynamics of outbreaking prey species. PMID:25930160

  20. Prey bacteria shape the community structure of their predators

    PubMed Central

    Chen, Huan; Athar, Rana; Zheng, Guili; Williams, Henry N

    2011-01-01

    Although predator–prey interactions among higher organisms have been studied extensively, only few examples are known for microbes other than protists and viruses. Among the bacteria, the most studied obligate predators are the Bdellovibrio and like organisms (BALOs) that prey on many other bacteria. In the macroscopical world, both predator and prey influence the population size of the other's community, and may have a role in selection. However, selective pressures among prey and predatory bacteria have been rarely investigated. In this study, Bacteriovorax, a predator within the group of BALOs, in environmental waters were fed two prey bacteria, Vibrio vulnificus and Vibrio parahaemolyticus. The two prey species yielded distinct Bacteriovorax populations, evidence that selective pressures shaped the predator community and diversity. The results of laboratory experiments confirmed the differential predation of Bacteriovorax phylotypes on the two bacteria species. Not only did Bacteriovorax Cluster IX exhibit the versatility to be the exclusive efficient predator on Vibrio vulnificus, thereby, behaving as a specialist, but was also able to prey with similar efficiency on Vibrio parahaemolyticus, indicative of a generalist. Therefore, we proposed a designation of versatilist for this predator. This initiative should provide a basis for further efforts to characterize the predatory patterns of bacterial predators. The results of this study have revealed impacts of the prey on Bacteriovorax predation and in structuring the predator community, and advanced understanding of predation behavior in the microbial world. PMID:21326335

  1. Prey capture kinematics of ant-eating lizards.

    PubMed

    Meyers, Jay J; Herrel, Anthony

    2005-01-01

    While morphological and behavioral feeding specializations are obvious in many vertebrate groups, among lizards there appear to be few dietary specialists. By comparing the prey capture kinematics and overall feeding behavior in two highly specialized ant-eating lizards (Moloch horridus and Phrynosoma platyrhinos) with those of two closely related dietary generalists (Pogona vitticeps and Uma notata), we investigate whether dietary specialization has been accompanied by changes in the function and use of the feeding system. We quantified kinematic variables from high-speed video recordings (200-250 frames s(-1)) of each species feeding on ants. Prey capture was strikingly different in M. horridus to that of other species, being characterized by a suite of unusual behaviors including the lack of a body lunge, faster tongue protrusion, reduced prey processing and, most notably, the ability to modulate the slow open phase of the gape cycle. In concert, these traits make a single feeding event in M. horridus faster than that in any other iguanian lizard studied to date. Prey capture behavior in P. platyrhinos is kinematically more similar to U. notata and P. vitticeps than to M. horridus, but the ant specialists are similar in that both lack distinct prey processing behaviors, resulting in faster overall capture and feeding events. While ant feeding in P. vitticeps is faster than feeding on other prey, the duration of a single feeding event is still four times longer than in either ant specialist, because of extensive prey processing. Additionally, a phylogenetic comparison of ant specialist lizards with dietary generalists revealed that ant-eating lizards require significantly less time to capture and process prey. Thus there are not only significant behavioral modifications in these ant-eating lizards, but also multiple strategies among specialists, suggesting differing selective pressures or phylogenetic constraints in the evolution of ant eating in lizards. PMID

  2. Irresistible ants: exposure to novel toxic prey increases consumption over multiple temporal scales.

    PubMed

    Herr, Mark W; Robbins, Travis R; Centi, Alan; Thawley, Christopher J; Langkilde, Tracy

    2016-07-01

    As species become increasingly exposed to novel challenges, it is critical to understand how evolutionary (i.e., generational) and plastic (i.e., within lifetime) responses work together to determine a species' fate or predict its distribution. The introduction of non-native species imposes novel pressures on the native species that they encounter. Understanding how native species exposed to toxic or distasteful invaders change their feeding behavior can provide insight into their ability to cope with these novel threats as well as broader questions about the evolution of this behavior. We demonstrated that native eastern fence lizards do not avoid consuming invasive fire ants following repeated exposure to this toxic prey. Rather fence lizards increased their consumption of these ants following exposure on three different temporal scales. Lizards ate more fire ants when they were exposed to this toxic prey over successive days. Lizards consumed more fire ants if they had been exposed to fire ants as juveniles 6 months earlier. Finally, lizards from populations exposed to fire ants over multiple generations consumed more fire ants than those from fire ant-free areas. These results suggest that the potentially lethal consumption of fire ants may carry benefits resulting in selection for this behavior, and learning that persists long after initial exposure. Future research on the response of native predators to venomous prey over multiple temporal scales will be valuable in determining the long-term effects of invasion by these novel threats. PMID:27000944

  3. Predicting violent behavior: The role of violence exposure and future educational aspirations during adolescence.

    PubMed

    Stoddard, Sarah A; Heinze, Justin E; Choe, Daniel Ewon; Zimmerman, Marc A

    2015-10-01

    Few researchers have explored future educational aspirations as a promotive factor against exposure to community violence in relation to adolescents' violent behavior over time. The present study examined the direct and indirect effect of exposure to community violence prior to 9th grade on attitudes about violence and violent behavior in 12th grade, and violent behavior at age 22 via 9th grade future educational aspirations in a sample of urban African American youth (n = 681; 49% male). Multi-group SEM was used to test the moderating effect of gender. Exposure to violence was associated with lower future educational aspirations. For boys, attitudes about violence directly predicted violent behavior at age 22. For boys, future educational aspirations indirectly predicted less violent behavior at age 22. Implications of the findings and suggestions for future research are discussed. PMID:26282242

  4. Emotional Responses to Environmental Messages and Future Behavioral Intentions

    ERIC Educational Resources Information Center

    Perrin, Jeffrey L.

    2011-01-01

    The present research investigated effects of message framing (losses-framed or gains-framed), message modality (video with text or text-only) and emotional arousal on environmentally responsible behavioral intentions. The sample consisted of 161 college students. The present research did not find a significant difference in behavioral intentions…

  5. Behavior Analysis: Thriving, but How about Its Future?

    ERIC Educational Resources Information Center

    Fantino, Edmund

    2008-01-01

    Behavior analysis has been thriving by continuing to make important theoretical and empirical contributions to a wide array of problems, as well as by contributing to interdisciplinary research. Applied research in behavior analysis is flourishing. Despite these positive signs there may be an erosion of support for basic research in animal…

  6. Behavior Genetics of Aggression in Children: Review and Future Directions.

    ERIC Educational Resources Information Center

    DiLalla, Lisabeth Fisher

    2002-01-01

    Argues that a thorough understanding of factors that influence aggression in children cannot be achieved without including behavior genetic studies that allow examination of the effects of shared versus non-shared environment, as well as genes, on aggressive behaviors. Details the growing body of evidence on the genetic effects on aggression.…

  7. Early Attachment Organization with Both Parents and Future Behavior Problems: From Infancy to Middle Childhood

    ERIC Educational Resources Information Center

    Kochanska, Grazyna; Kim, Sanghag

    2013-01-01

    Links between children's attachment security with mothers and fathers, assessed in Strange Situation with each parent at 15 months ("N" = 101), and their future behavior problems were examined. Mothers and fathers rated children's behavior problems, and children reported their own behavior problems at age 8 ("N" = 86). Teachers rated behavior…

  8. Anti-aversive effects of cannabidiol on innate fear-induced behaviors evoked by an ethological model of panic attacks based on a prey vs the wild snake Epicrates cenchria crassus confrontation paradigm.

    PubMed

    Uribe-Mariño, Andrés; Francisco, Audrey; Castiblanco-Urbina, Maria Angélica; Twardowschy, André; Salgado-Rohner, Carlos José; Crippa, José Alexandre S; Hallak, Jaime Eduardo Cecílio; Zuardi, Antônio Waldo; Coimbra, Norberto Cysne

    2012-01-01

    Several pharmacological targets have been proposed as modulators of panic-like reactions. However, interest should be given to other potential therapeutic neurochemical agents. Recent attention has been given to the potential anxiolytic properties of cannabidiol, because of its complex actions on the endocannabinoid system together with its effects on other neurotransmitter systems. The aim of this study was to investigate the effects of cannabidiol on innate fear-related behaviors evoked by a prey vs predator paradigm. Male Swiss mice were submitted to habituation in an arena containing a burrow and subsequently pre-treated with intraperitoneal administrations of vehicle or cannabidiol. A constrictor snake was placed inside the arena, and defensive and non-defensive behaviors were recorded. Cannabidiol caused a clear anti-aversive effect, decreasing explosive escape and defensive immobility behaviors outside and inside the burrow. These results show that cannabidiol modulates defensive behaviors evoked by the presence of threatening stimuli, even in a potentially safe environment following a fear response, suggesting a panicolytic effect. PMID:21918503

  9. Goshawk prey have more bacteria than non-prey.

    PubMed

    Møller, A P; Peralta-Sánchez, J M; Nielsen, J T; López-Hernández, E; Soler, J J

    2012-03-01

    1. Predators often prey on individuals that are sick or otherwise weakened. Although previous studies have shown higher abundance of parasites in prey, whether prey have elevated loads of micro-organisms remains to be determined. 2. We quantified the abundance of bacteria and fungi on feathers of woodpigeons Columba palumbus L., jays Garrulus glandarius L. and blackbirds Turdus merula L. that either fell prey to goshawks Accipiter gentilis L. or were not depredated. 3. We found an almost three-fold increase in bacterial load of prey compared with non-prey, while there was no significant difference between prey and non-prey in level of fungal infection of the plumage. 4. The results were not confounded by differences in size or mass of feathers, date of collection of feathers, or date of analysis of feathers for micro-organisms. 5. These findings suggest a previously unknown contribution of bacteria to risk of predation, with important implications for behaviour, population ecology and community ecology. PMID:22039986

  10. Behavioral Intervention Technologies: Evidence review and recommendations for future research

    PubMed Central

    Mohr, David C.; Burns, Michelle Nicole; Schueller, Stephen M.; Clarke, Gregory; Klinkman, Michael

    2013-01-01

    This paper reports on the findings of a technical expert panel convened by the Agency for Healthcare Research and Quality and the National Institute of Mental Health, charged with reviewing the state of research on behavioral intervention technologies (BITs) in mental health and identifying the top research priorities. BITs is the comprehensive term used to refer to behavioral and psychological interventions that use information and communication technology features to address behavioral and mental health outcomes. Mental health BITs using videoconferencing and standard telephone technologies to deliver psychotherapy have been wellvalidated. Web-based interventions have shown efficacy across a broad range of mental health outcomes, although outcomes vary widely. Social media such as online support groups have produced generally disappointing outcomes when used alone. Mobile technologies have received limited attention for mental health outcomes, although findings from behavioral health suggest they are promising. Virtual reality has shown good efficacy for anxiety and pediatric disorders. Serious gaming has received relatively little work in mental health. Recommendations for next step research in each of these are made. Research focused on understanding of reach, adherence, barriers and cost is recommended. As BITs can generate large amounts of data, improvements in the collection, storage, analysis, and visualization of big data will be required. Traditional psychological and behavioral theories have proven insufficient to understand how BITs produce behavioral change. Thus new theoretical models, as well as new evaluation strategies, will be required. Finally, for BITs to have a public health impact, research on implementation and application to prevention will be required. PMID:23664503

  11. Predator-prey systems depend on a prey refuge.

    PubMed

    Chivers, W J; Gladstone, W; Herbert, R D; Fuller, M M

    2014-11-01

    Models of near-exclusive predator-prey systems such as that of the Canadian lynx and snowshoe hare have included factors such as a second prey species, a Holling Type II predator response and climatic or seasonal effects to reproduce sub-sets of six signature patterns in the empirical data. We present an agent-based model which does not require the factors or constraints of previous models to reproduce all six patterns in persistent populations. Our parsimonious model represents a generalised predator and prey species with a small prey refuge. The lack of the constraints of previous models, considered to be important for those models, casts doubt on the current hypothesised mechanisms of exclusive predator-prey systems. The implication for management of the lynx, a protected species, is that maintenance of an heterogeneous environment offering natural refuge areas for the hare is the most important factor for the conservation of this species. PMID:25058806

  12. Educating Future Therapists about the Controversy Surrounding Managed Behavioral Healthcare.

    ERIC Educational Resources Information Center

    Chambliss, Catherine

    The mental health care delivery system is undergoing a metamorphosis of unprecedented proportion as managed care covers more and more patients. This dramatic change has its critics (many mental health professionals) and its enthusiastics (the managed behavioral health care companies). Some of these issues are presented in this paper. There is…

  13. Rational Emotive Behavior Therapy after Ellis: Predictions for the Future.

    ERIC Educational Resources Information Center

    Weinrach, Stephen G.; Ellis, Albert; DiGiuseppe, Raymond; Bernard, Michael E.; Dryden, Windy; Kassinove, Howard; Morris, G. Barry; Vernon, Ann; Wolfe, Janet

    1995-01-01

    Nine members of the institute for Rational-Emotive Therapy's (REBT) International Training Standards and Review Committee predicted the status of REBT 25 to 50 years after the death of Albert Ellis. Will REBT continue to exist in its own right or be incorporated into newer forms of cognitive behavior therapy? (EMK)

  14. Birds of Prey of Wisconsin.

    ERIC Educational Resources Information Center

    Hamerstrom, Frances

    This copiously illustrated document is designed to be a field quide to birds of prey that are common to Wisconsin, as well as to some that enter the state occasionally. An introduction discusses birds of prey with regard to migration patterns, the relationship between common names and the attitudes of people toward certain birds, and natural signs…

  15. Fabrication and electrochemical behavior of nitride fuel for future applications

    NASA Astrophysics Data System (ADS)

    Arai, Yasuo; Minato, Kazuo

    2005-09-01

    Mononitride is the first candidate of fuel material in the accelerator driven system (ADS) for minor actinide (MA) transmutation designed by JAERI, being coupled with pyrochemical process for treatment of spent fuel. This paper summarizes recent R&D on the fabrication and electrochemical behavior of nitride fuel carried out in JAERI. Mononitride of U, Np, Pu, Am, Cm and their solid solutions have been prepared by carbothermic reduction from their dioxides. Mononitride containing diluent material such as ZrN also has been prepared and characterized. Electrode behavior of nitride fuel in the LiCl-KCl eutectic melt has been investigated by electrochemical measurements in order to apply pyrochemical process to nitride fuel cycle for MA transmutation.

  16. Stock Portfolio Structure of Individual Investors Infers Future Trading Behavior

    PubMed Central

    Bohlin, Ludvig; Rosvall, Martin

    2014-01-01

    Although the understanding of and motivation behind individual trading behavior is an important puzzle in finance, little is known about the connection between an investor's portfolio structure and her trading behavior in practice. In this paper, we investigate the relation between what stocks investors hold, and what stocks they buy, and show that investors with similar portfolio structures to a great extent trade in a similar way. With data from the central register of shareholdings in Sweden, we model the market in a similarity network, by considering investors as nodes, connected with links representing portfolio similarity. From the network, we find investor groups that not only identify different investment strategies, but also represent individual investors trading in a similar way. These findings suggest that the stock portfolios of investors hold meaningful information, which could be used to earn a better understanding of stock market dynamics. PMID:25068302

  17. Stock portfolio structure of individual investors infers future trading behavior.

    PubMed

    Bohlin, Ludvig; Rosvall, Martin

    2014-01-01

    Although the understanding of and motivation behind individual trading behavior is an important puzzle in finance, little is known about the connection between an investor's portfolio structure and her trading behavior in practice. In this paper, we investigate the relation between what stocks investors hold, and what stocks they buy, and show that investors with similar portfolio structures to a great extent trade in a similar way. With data from the central register of shareholdings in Sweden, we model the market in a similarity network, by considering investors as nodes, connected with links representing portfolio similarity. From the network, we find investor groups that not only identify different investment strategies, but also represent individual investors trading in a similar way. These findings suggest that the stock portfolios of investors hold meaningful information, which could be used to earn a better understanding of stock market dynamics. PMID:25068302

  18. Preference and prey switching in a generalist predator attacking local and invasive alien pests.

    PubMed

    Jaworski, Coline C; Bompard, Anaïs; Genies, Laure; Amiens-Desneux, Edwige; Desneux, Nicolas

    2013-01-01

    Invasive pest species may strongly affect biotic interactions in agro-ecosystems. The ability of generalist predators to prey on new invasive pests may result in drastic changes in the population dynamics of local pest species owing to predator-mediated indirect interactions among prey. On a short time scale, the nature and strength of such indirect interactions depend largely on preferences between prey and on predator behavior patterns. Under laboratory conditions we evaluated the prey preference of the generalist predator Macrolophus pygmaeus Rambur (Heteroptera: Miridae) when it encounters simultaneously the local tomato pest Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) and the invasive alien pest Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae). We tested various ratios of local vs. alien prey numbers, measuring switching by the predator from one prey to the other, and assessing what conditions (e.g. prey species abundance and prey development stage) may favor such prey switching. The total predation activity of M. pygmaeus was affected by the presence of T. absoluta in the prey complex with an opposite effect when comparing adult and juvenile predators. The predator showed similar preference toward T. absoluta eggs and B. tabaci nymphs, but T. absoluta larvae were clearly less attacked. However, prey preference strongly depended on prey relative abundance with a disproportionately high predation on the most abundant prey and disproportionately low predation on the rarest prey. Together with the findings of a recent companion study (Bompard et al. 2013, Population Ecology), the insight obtained on M. pygmaeus prey switching may be useful for Integrated Pest Management in tomato crops, notably for optimal simultaneous management of B. tabaci and T. absoluta, which very frequently co-occur on tomato. PMID:24312646

  19. The Development and Coherence of Future-Oriented Behaviors during the Preschool Years

    ERIC Educational Resources Information Center

    Atance, Cristina M.; Jackson, Laura K.

    2009-01-01

    Although previous research has identified a number of interesting aspects of future thinking in adults, little is known about the developmental trajectory and coherence of future-oriented behaviors during early childhood. The primary goal of this study was to explore these issues by administering a battery of tasks assessing different aspects of…

  20. Relationships Between Future Orientation, Impulsive Sensation Seeking, and Risk Behavior Among Adjudicated Adolescents

    ERIC Educational Resources Information Center

    Robbins, Reuben N.; Bryan, Angela

    2004-01-01

    Because of high levels of risk behavior, adjudicated adolescents are at high risk for negative health outcomes such as nicotine and drug addiction and sexually transmitted diseases. The goal of this article is to examine relationships between future orientation and impulsive-sensation-seeking personality constructs to risk behaviors among 300…

  1. Linking biomechanics and ecology through predator-prey interactions: flight performance of dragonflies and their prey.

    PubMed

    Combes, S A; Rundle, D E; Iwasaki, J M; Crall, J D

    2012-03-15

    Aerial predation is a highly complex, three-dimensional flight behavior that affects the individual fitness and population dynamics of both predator and prey. Most studies of predation adopt either an ecological approach in which capture or survival rates are quantified, or a biomechanical approach in which the physical interaction is studied in detail. In the present study, we show that combining these two approaches provides insight into the interaction between hunting dragonflies (Libellula cyanea) and their prey (Drosophila melanogaster) that neither type of study can provide on its own. We performed >2500 predation trials on nine dragonflies housed in an outdoor artificial habitat to identify sources of variability in capture success, and analyzed simultaneous predator-prey flight kinematics from 50 high-speed videos. The ecological approach revealed that capture success is affected by light intensity in some individuals but that prey density explains most of the variability in success rate. The biomechanical approach revealed that fruit flies rarely respond to approaching dragonflies with evasive maneuvers, and are rarely successful when they do. However, flies perform random turns during flight, whose characteristics differ between individuals, and these routine, erratic turns are responsible for more failed predation attempts than evasive maneuvers. By combining the two approaches, we were able to determine that the flies pursued by dragonflies when prey density is low fly more erratically, and that dragonflies are less successful at capturing them. This highlights the importance of considering the behavior of both participants, as well as their biomechanics and ecology, in developing a more integrative understanding of organismal interactions. PMID:22357584

  2. Prey size structure diminishes cascading effects by increasing interference competition and predation among prey.

    PubMed

    Geraldii, Nathan R

    2015-09-01

    The size of an organism can change by orders of magnitude during its lifespan. Size can determine whether an individual consumes, is consumed, competes, or avoids individuals of the same or different species. Two complementary mesocosm experiments with a tri-trophic food chain (top predator, toadfish, Opsanus tau; intermediate prey, mud crab, family Xanthidae; basal resource, oyster, Crassostrea virginica) were conducted to measure how the size of both the top predator and the intermediate prey affects consumptive and behavioral interactions in trophic cascades. In the first experiment, I systematically varied the sizes of predators and prey, respectively. The amount of crab biomass consumed was dependent on crab size and not toadfish size, but the effect of crab size did not cascade to alter oyster survival. Increased oyster survival from crab interference competition in the absence of toadfish was similar to oyster survival,from predator-avoidance behavior in the presence of a toadfish. When all crab size classes were present, crab mortality was similar in the presence and absence of toadfish, highlighting the importance of intraguild predation in food-web dynamics. The second experiment separated crab mortality by other crabs from crab mortality by predatory toadfish and found that crab mortality generally switched from intra- to interguild predation when a toadfish was present. In addition, field surveys indicated mud crab abundance and size was primarily influenced by mud crab recruitment, but not by toadfish abundance, which supports our experimental results that interactions among mud crabs have similar effects to predator-prey interactions. These findings indicate that changes in size or abundance of intermediate prey may be comparable to changes in top predator abundance in terms of trophic interactions and their transmission to lower levels, which suggests that certain types of relatively simple food chains can be resilient to the loss of higher trophic

  3. Future Directions in the Study of Health Behavior among Older Adults.

    PubMed

    Ziegelmann, Jochen P; Knoll, Nina

    2015-01-01

    The study of health behaviors and fostering health-behavior change is an important endeavor even in old age. The aim of this viewpoint article is threefold. First, we use a broad perspective for the definition of health behaviors to capture all relevant aspects of health-behavior change in older adults. Particularly, we suggest a distinction between proximal (e.g., physical activity) and distal health behaviors (e.g., social participation). Second, we recommend a stronger orientation towards processes in order to study health behaviors and the design of health-behavior change interventions. Third, we review the advantages of a developmental perspective in health psychology. Future directions in the study of health behavior among older adults are discussed. PMID:25660128

  4. Prey-predator model with a nonlocal consumption of prey.

    PubMed

    Banerjee, M; Volpert, V

    2016-08-01

    The prey-predator model with nonlocal consumption of prey introduced in this work extends previous studies of local reaction-diffusion models. Linear stability analysis of the homogeneous in space stationary solution and numerical simulations of nonhomogeneous solutions allow us to analyze bifurcations and dynamics of stationary solutions and of travelling waves. These solutions present some new properties in comparison with the local models. They correspond to different feeding strategies of predators observed in ecology. PMID:27586616

  5. Infomechanical specializations for prey capture in knifefish

    NASA Astrophysics Data System (ADS)

    Maciver, Malcolm; Patankar, Neelesh; Curet, Oscar; Shirgaonkar, Anup

    2007-11-01

    How does an animal's mechanics and its information acquisition system work together to solve crucial behavioral tasks? We examine this question for the black ghost weakly electric knifefish (Apteronotus albifrons), which is a leading model system for the study of sensory processing in vertebrates. These animals hunt at night by detecting perturbations of a self-generated electric field caused by prey. While the fish searches for prey, it pitches at 30 . Fully resolved Navier-Stokes simulations of their swimming, which occurs through undulations of a long ribbon-like fin along the bottom edge of the body, indicates that this configuration enables maximal thrust while minimizing pitch moment. However, pitching the body also increases drag. Our analysis of the sensory volume for detection of prey shows this volume to be similar to a cylinder around the body. Thus, pitching the body enables a greater swept volume of scanned fluid. Examining the mechanical and information acquisition demands on the animal in this task gives insight into how these sometimes conflicting demands are resolved.

  6. Functional responses of the rough-legged buzzard in a multi-prey system.

    PubMed

    Hellström, P; Nyström, J; Angerbjörn, A

    2014-04-01

    The functional response is a key element of predator-prey interactions. Basic functional response theory explains foraging behavior of individual predators, but many empirical studies of free-ranging predators have estimated functional responses by using population-averaged data. We used a novel approach to investigate functional responses of an avian predator (the rough legged-buzzard Buteo lagopus Pontoppidan, 1763) to intra-annual spatial variation in rodent density in subarctic Sweden, using breeding pairs as the sampling unit. The rough-legged buzzards responded functionally to Norwegian lemmings (Lemmus lemmus L. 1758), grey-sided voles (Myodes rufocanus Sundevall, 1846) and field voles (Microtus agrestis L. 1761), but different rodent prey were not utilised according to relative abundance. The functional response to Norwegian lemmings was a steep type II curve and a more shallow type III response to grey-sided voles. The different shapes of these two functional responses were likely due to combined effects of differences between lemmings and grey-sided voles in habitat utilisation, anti-predator behaviour and size-dependent vulnerability to predation. Diet composition changed less than changes in relative prey abundance, indicating negative switching, with high disproportional use of especially lemmings at low relative densities. Our results suggest that lemmings and voles should be treated separately in future empirical and theoretical studies in order to better understand the role of predation in this study system. PMID:24448699

  7. A dedicated visual pathway for prey detection in larval zebrafish

    PubMed Central

    Semmelhack, Julia L; Donovan, Joseph C; Thiele, Tod R; Kuehn, Enrico; Laurell, Eva; Baier, Herwig

    2014-01-01

    Zebrafish larvae show characteristic prey capture behavior in response to small moving objects. The neural mechanism used to recognize objects as prey remains largely unknown. We devised a machine learning behavior classification system to quantify hunting kinematics in semi-restrained animals exposed to a range of virtual stimuli. Two-photon calcium imaging revealed a small visual area, AF7, that was activated specifically by the optimal prey stimulus. This pretectal region is innervated by two types of retinal ganglion cells, which also send collaterals to the optic tectum. Laser ablation of AF7 markedly reduced prey capture behavior. We identified neurons with arbors in AF7 and found that they projected to multiple sensory and premotor areas: the optic tectum, the nucleus of the medial longitudinal fasciculus (nMLF) and the hindbrain. These findings indicate that computations in the retina give rise to a visual stream which transforms sensory information into a directed prey capture response. DOI: http://dx.doi.org/10.7554/eLife.04878.001 PMID:25490154

  8. Chimpanzees prey on army ants with specialized tool set.

    PubMed

    Sanz, Crickette M; Schöning, Caspar; Morgan, David B

    2010-01-01

    Several populations of chimpanzees have been reported to prey upon Dorylus army ants. The most common tool-using technique to gather these ants is with "dipping" probes, which vary in length with regard to aggressiveness and lifestyle of the prey species. We report the use of a tool set in army ant predation by chimpanzees in the Goualougo Triangle, Republic of Congo. We recovered 1,060 tools used in this context and collected 25 video recordings of chimpanzee tool-using behavior at ant nests. Two different types of tools were distinguished based on their form and function. The chimpanzees use a woody sapling to perforate the ant nest, and then a herb stem as a dipping tool to harvest the ants. All of the species of ants preyed upon in Goualougo are present and consumed by chimpanzees at other sites, but there are no other reports of such a regular or widespread use of more than one type of tool to prey upon Dorylus ants. Furthermore, this tool set differs from other types of tool combinations used by chimpanzees at this site for preying upon termites or gathering honey. Therefore, we conclude that these chimpanzees have developed a specialized method for preying upon army ants, which involves the use of an additional tool for opening nests. Further research is needed to determine which specific ecological and social factors may have shaped the emergence and maintenance of this technology. PMID:19731231

  9. Modeling Behavior by Coastal River Otter (Lontra Canadensis) in Response to Prey Availability in Prince William Sound, Alaska: A Spatially-Explicit Individual-Based Approach.

    PubMed

    Albeke, Shannon E; Nibbelink, Nathan P; Ben-David, Merav

    2015-01-01

    Effects of climate change on animal behavior and cascading ecosystem responses are rarely evaluated. In coastal Alaska, social river otters (Lontra Canadensis), largely males, cooperatively forage on schooling fish and use latrine sites to communicate group associations and dominance. Conversely, solitary otters, mainly females, feed on intertidal-demersal fish and display mutual avoidance via scent marking. This behavioral variability creates "hotspots" of nutrient deposition and affects plant productivity and diversity on the terrestrial landscape. Because the abundance of schooling pelagic fish is predicted to decline with climate change, we developed a spatially-explicit individual-based model (IBM) of otter behavior and tested six scenarios based on potential shifts to distribution patterns of schooling fish. Emergent patterns from the IBM closely mimicked observed otter behavior and landscape use in the absence of explicit rules of intraspecific attraction or repulsion. Model results were most sensitive to rules regarding spatial memory and activity state following an encounter with a fish school. With declining availability of schooling fish, the number of social groups and the time simulated otters spent in the company of conspecifics declined. Concurrently, model results suggested an elevation of defecation rate, a 25% increase in nitrogen transport to the terrestrial landscape, and significant changes to the spatial distribution of "hotspots" with declines in schooling fish availability. However, reductions in availability of schooling fish could lead to declines in otter density over time. PMID:26061497

  10. Modeling Behavior by Coastal River Otter (Lontra Canadensis) in Response to Prey Availability in Prince William Sound, Alaska: A Spatially-Explicit Individual-Based Approach

    PubMed Central

    Albeke, Shannon E.; Nibbelink, Nathan P.; Ben-David, Merav

    2015-01-01

    Effects of climate change on animal behavior and cascading ecosystem responses are rarely evaluated. In coastal Alaska, social river otters (Lontra Canadensis), largely males, cooperatively forage on schooling fish and use latrine sites to communicate group associations and dominance. Conversely, solitary otters, mainly females, feed on intertidal-demersal fish and display mutual avoidance via scent marking. This behavioral variability creates “hotspots” of nutrient deposition and affects plant productivity and diversity on the terrestrial landscape. Because the abundance of schooling pelagic fish is predicted to decline with climate change, we developed a spatially-explicit individual-based model (IBM) of otter behavior and tested six scenarios based on potential shifts to distribution patterns of schooling fish. Emergent patterns from the IBM closely mimicked observed otter behavior and landscape use in the absence of explicit rules of intraspecific attraction or repulsion. Model results were most sensitive to rules regarding spatial memory and activity state following an encounter with a fish school. With declining availability of schooling fish, the number of social groups and the time simulated otters spent in the company of conspecifics declined. Concurrently, model results suggested an elevation of defecation rate, a 25% increase in nitrogen transport to the terrestrial landscape, and significant changes to the spatial distribution of “hotspots” with declines in schooling fish availability. However, reductions in availability of schooling fish could lead to declines in otter density over time. PMID:26061497

  11. Sensing the strike of a predator fish depends on the specific gravity of a prey fish.

    PubMed

    Stewart, William J; McHenry, Matthew J

    2010-11-15

    The ability of a predator fish to capture a prey fish depends on the hydrodynamics of the prey and its behavioral response to the predator's strike. Despite the importance of this predator-prey interaction to the ecology and evolution of a diversity of fish, it is unclear what factors dictate a fish's ability to evade capture. The present study evaluated how the specific gravity of a prey fish's body affects the kinematics of prey capture and the signals detected by the lateral line system of the prey during the strike of a suction-feeding predator. The specific gravity of zebrafish (Danio rerio) larvae was measured with high precision from recordings of terminal velocity in solutions of varying density. This novel method found that specific gravity decreased by ∼5% (from 1.063, N=8, to 1.011, N=35) when the swim bladder inflates. To examine the functional consequences of this change, we developed a mathematical model of the hydrodynamics of prey in the flow field created by a suction-feeding predator. This model found that the observed decrease in specific gravity due to swim bladder inflation causes an 80% reduction of the flow velocity around the prey's body. Therefore, swim bladder inflation causes a substantial reduction in the flow signal that may be sensed by the lateral line system to evade capture. These findings demonstrate that the ability of a prey fish to sense a predator depends crucially on the specific gravity of the prey. PMID:21037055

  12. What you need is what you eat? Prey selection by the bat Myotis daubentonii.

    PubMed

    Vesterinen, Eero J; Ruokolainen, Lasse; Wahlberg, Niklas; Peña, Carlos; Roslin, Tomas; Laine, Veronika N; Vasko, Ville; Sääksjärvi, Ilari E; Norrdahl, Kai; Lilley, Thomas M

    2016-04-01

    Optimal foraging theory predicts that predators are selective when faced with abundant prey, but become less picky when prey gets sparse. Insectivorous bats in temperate regions are faced with the challenge of building up fat reserves vital for hibernation during a period of decreasing arthropod abundances. According to optimal foraging theory, prehibernating bats should adopt a less selective feeding behavior--yet empirical studies have revealed many apparently generalized species to be composed of specialist individuals. Targeting the diet of the bat Myotis daubentonii, we used a combination of molecular techniques to test for seasonal changes in prey selectivity and individual-level variation in prey preferences. DNA metabarcoding was used to characterize both the prey contents of bat droppings and the insect community available as prey. To test for dietary differences among M. daubentonii individuals, we used ten microsatellite loci to assign droppings to individual bats. The comparison between consumed and available prey revealed a preference for certain prey items regardless of availability. Nonbiting midges (Chironomidae) remained the most highly consumed prey at all times, despite a significant increase in the availability of black flies (Simuliidae) towards the end of the season. The bats sampled showed no evidence of individual specialization in dietary preferences. Overall, our approach offers little support for optimal foraging theory. Thus, it shows how novel combinations of genetic markers can be used to test general theory, targeting patterns at both the level of prey communities and individual predators. PMID:26841188

  13. Behavioral genetics '97: ASHG statement. Recent developments in human behavioral genetics: past accomplishments and future directions.

    PubMed Central

    Sherman, S L; DeFries, J C; Gottesman, I I; Loehlin, J C; Meyer, J M; Pelias, M Z; Rice, J; Waldman, I

    1997-01-01

    The field of behavioral genetics has enormous potential to uncover both genetic and environmental influences on normal and deviant behavior. Behavioral-genetic methods are based on a solid foundation of theories and methods that successfully have delineated components of complex traits in plants and animals. New resources are now available to dissect the genetic component of these complex traits. As specific genes are identified, we can begin to explore how these interact with environmental factors in development. How we interpret such findings, how we ask new questions, how we celebrate the knowledge, and how we use or misuse this knowledge are all important considerations. These issues are pervasive in all areas of human research, and they are especially salient in human behavioral genetics. PMID:9199545

  14. Seasonal foraging ecology of non-migratory cougars in a system with migrating prey.

    PubMed

    Elbroch, L Mark; Lendrum, Patrick E; Newby, Jesse; Quigley, Howard; Craighead, Derek

    2013-01-01

    We tested for seasonal differences in cougar (Puma concolor) foraging behaviors in the Southern Yellowstone Ecosystem, a multi-prey system in which ungulate prey migrate, and cougars do not. We recorded 411 winter prey and 239 summer prey killed by 28 female and 10 male cougars, and an additional 37 prey items by unmarked cougars. Deer composed 42.4% of summer cougar diets but only 7.2% of winter diets. Males and females, however, selected different proportions of different prey; male cougars selected more elk (Cervus elaphus) and moose (Alces alces) than females, while females killed greater proportions of bighorn sheep (Ovis canadensis), pronghorn (Antilocapra americana), mule deer (Odocoileus hemionus) and small prey than males. Kill rates did not vary by season or between males and females. In winter, cougars were more likely to kill prey on the landscape as: 1) elevation decreased, 2) distance to edge habitat decreased, 3) distance to large bodies of water decreased, and 4) steepness increased, whereas in summer, cougars were more likely to kill in areas as: 1) elevation decreased, 2) distance to edge habitat decreased, and 3) distance from large bodies of water increased. Our work highlighted that seasonal prey selection exhibited by stationary carnivores in systems with migratory prey is not only driven by changing prey vulnerability, but also by changing prey abundances. Elk and deer migrations may also be sustaining stationary cougar populations and creating apparent competition scenarios that result in higher predation rates on migratory bighorn sheep in winter and pronghorn in summer. Nevertheless, cougar predation on rare ungulates also appeared to be influenced by individual prey selection. PMID:24349498

  15. Seasonal Foraging Ecology of Non-Migratory Cougars in a System with Migrating Prey

    PubMed Central

    Elbroch, L. Mark; Lendrum, Patrick E.; Newby, Jesse; Quigley, Howard; Craighead, Derek

    2013-01-01

    We tested for seasonal differences in cougar (Puma concolor) foraging behaviors in the Southern Yellowstone Ecosystem, a multi-prey system in which ungulate prey migrate, and cougars do not. We recorded 411 winter prey and 239 summer prey killed by 28 female and 10 male cougars, and an additional 37 prey items by unmarked cougars. Deer composed 42.4% of summer cougar diets but only 7.2% of winter diets. Males and females, however, selected different proportions of different prey; male cougars selected more elk (Cervus elaphus) and moose (Alces alces) than females, while females killed greater proportions of bighorn sheep (Ovis canadensis), pronghorn (Antilocapra americana), mule deer (Odocoileus hemionus) and small prey than males. Kill rates did not vary by season or between males and females. In winter, cougars were more likely to kill prey on the landscape as: 1) elevation decreased, 2) distance to edge habitat decreased, 3) distance to large bodies of water decreased, and 4) steepness increased, whereas in summer, cougars were more likely to kill in areas as: 1) elevation decreased, 2) distance to edge habitat decreased, and 3) distance from large bodies of water increased. Our work highlighted that seasonal prey selection exhibited by stationary carnivores in systems with migratory prey is not only driven by changing prey vulnerability, but also by changing prey abundances. Elk and deer migrations may also be sustaining stationary cougar populations and creating apparent competition scenarios that result in higher predation rates on migratory bighorn sheep in winter and pronghorn in summer. Nevertheless, cougar predation on rare ungulates also appeared to be influenced by individual prey selection. PMID:24349498

  16. Suicidal Behavior and Loss of the Future Self in Semantic Dementia

    PubMed Central

    Hsiao, Julia J.; Kaiser, Natalie; Fong, Sylvia; Mendez, Mario F.

    2013-01-01

    Semantic dementia impairs semantic autobiographical memory, but tends to spare its episodic components that are critical for the sense of self. Investigators have recently discovered disturbances in the “future self” in semantic dementia. We report a 63-year-old man with semantic dementia who was hospitalized after suicide attempts that he attributed to his loss of a sense of future self. He complained of a decreased sense of being human, because he could not imagine doing things in the future that he had done in the past. Suicidal thinking and inability to place himself in future tasks persisted despite resolution of depression. Clinical assessment revealed a crossmodal loss of semantic knowledge, and neuroimaging showed bilateral anterior temporal atrophy and hypometabolism. On specific tests of autobiographical memory, identity, attribute knowledge, and future projection, the patient could return to the past and visualize himself in familiar scenarios, but he could not visualize himself even passively in these scenarios in the future. His future self was impaired not from seeing himself disabled; it was from an absence of semantic details of potential experiences, associated with impaired semantic autobiographical memory. His self-representations were concrete and specific rather than abstract and generalizable. This patient and recent publications indicate that semantic dementia impairs the ability to imagine oneself as capable in the future, leading some patients to suicidal behavior. We discuss possible mechanisms for these findings, including the potential role of abstract construals for future thinking. PMID:23812172

  17. Beyond freedom and dignity at 40: comments on behavioral science, the future, and chance (2007).

    PubMed

    Leigland, Sam

    2011-01-01

    Forty years after the publication of Beyond Freedom and Dignity (Skinner, 1971) and the continuing growth of behavior analysis, the future of humanity and the role of behavioral science in that future remain uncertain. A recent paper by Chance (2007) documented a shift in Skinner's views during the last years of his life. Skinner had long advocated a science and technology of behavior for finding and engineering solutions to cultural and global problems and advancing human development. This optimism had given way under a gradual realization that the science of behavior was in fact showing how such problems were unlikely to be solved in time to avert a variety of possible disasters. Chance described nine behavioral phenomena that appear to interfere with effective problem-solving behavior on a large scale and in effective time frames. These phenomena are reviewed toward an analysis of common themes. Research is also reviewed that involves nonverbal, verbal, and cultural contingencies that may lead to applications designed to address the common themes. Problems and strategies of implementation are also discussed. The challenges are daunting, but may nevertheless be regarded as technical problems best suited for a science and technology of behavior. PMID:22532749

  18. Beyond Freedom and Dignity at 40: Comments on Behavioral Science, the Future, and Chance (2007)

    PubMed Central

    Leigland, Sam

    2011-01-01

    Forty years after the publication of Beyond Freedom and Dignity (Skinner, 1971) and the continuing growth of behavior analysis, the future of humanity and the role of behavioral science in that future remain uncertain. A recent paper by Chance (2007) documented a shift in Skinner's views during the last years of his life. Skinner had long advocated a science and technology of behavior for finding and engineering solutions to cultural and global problems and advancing human development. This optimism had given way under a gradual realization that the science of behavior was in fact showing how such problems were unlikely to be solved in time to avert a variety of possible disasters. Chance described nine behavioral phenomena that appear to interfere with effective problem-solving behavior on a large scale and in effective time frames. These phenomena are reviewed toward an analysis of common themes. Research is also reviewed that involves nonverbal, verbal, and cultural contingencies that may lead to applications designed to address the common themes. Problems and strategies of implementation are also discussed. The challenges are daunting, but may nevertheless be regarded as technical problems best suited for a science and technology of behavior. PMID:22532749

  19. Future Time Perspective as a Predictor of Adolescents' Adaptive Behavior in School

    ERIC Educational Resources Information Center

    Carvalho, Renato Gil Gomes

    2015-01-01

    Future time perspective (FTP) has been associated with positive outcomes in adolescents' development across different contexts. However, the extent to which FTP influences adaptation needs additional understanding. In this study, we analysed the relationship between FTP and adolescents' behavior in school, as expressed in several indicators of…

  20. Indirect effects of prey swamping: differential seed predation during a bamboo masting event.

    PubMed

    Kitzberger, Thomas; Chaneton, Enrique J; Caccia, Fernando

    2007-10-01

    Resource pulses often involve extraordinary increases in prey availability that "swamp" consumers and reverberate through indirect interactions affecting other community members. We developed a model that predicts predator-mediated indirect effects induced by an epidemic prey on co-occurring prey types differing in relative profitability/preference and validated our model by examining current-season and delayed effects of a bamboo mass seeding event on seed survival of canopy tree species in mixed Patagonian forests. The model shows that predator foraging behavior, prey profitability, and the scale of prey swamping influence the character and strength of short-term indirect effects on various alternative prey. When in large prey-swamped patches, nonselective predators decrease predation on all prey types. Selective predators, instead, only benefit prey of similar quality to the swamping species, while very low or high preference prey remain unaffected. Negative indirect effects (apparent competition) may override such positive effects (apparent mutualism), especially for highly preferred prey, when prey-swamped patches are small enough to allow predator aggregation and/or predators show a reproductive numerical response to elevated food supply. Seed predation patterns during bamboo (Chusquea culeou) masting were consistent with predicted short-term indirect effects mediated by a selective predator foraging in large prey-swamped patches. Bamboo seeds and similarly-sized Austrocedrus chilensis (ciprés) and Nothofagus obliqua (roble) seeds suffered lower predation in bamboo flowered than nonflowered patches. Predation rates on the small-seeded Nothofagus dombeyi (coihue) and the large-seeded Nothofagus alpina (rauli) were independent of bamboo flowering. Indirect positive effects were transient; three months after bamboo seeding, granivores preyed heavily upon all seed types, irrespective of patch flowering condition. Moreover, one year after bamboo seeding

  1. Predator cannibalism can intensify negative impacts on heterospecific prey.

    PubMed

    Takatsu, Kunio; Kishida, Osamu

    2015-07-01

    Although natural populations consist of individuals with different traits, and the degree of phenotypic variation varies among populations, the impact of phenotypic variation on ecological interactions has received little attention, because traditional approaches to community ecology assume homogeneity of individuals within a population. Stage structure, which is a common way of generating size and developmental variation within predator populations, can drive cannibalistic interactions, which can affect the strength of predatory effects on the predator's heterospecific prey. Studies have shown that predator cannibalism weakens predatory effects on heterospecific prey by reducing the size of the predator population and by inducing less feeding activity of noncannibal predators. We predict, however, that predator cannibalism, by promoting rapid growth of the cannibals, can also intensify predation pressure on heterospecific prey, because large predators have large resource requirements and may utilize a wider variety of prey species. To test this hypothesis, we conducted an experiment in which we created carnivorous salamander (Hynobius retardatus) populations with different stage structures by manipulating the salamander's hatch timing (i.e., populations with large or small variation in the timing of hatching), and explored the resultant impacts on the abundance, behavior, morphology, and life history of the salamander's large heterospecific prey, Rana pirica frog tadpoles. Cannibalism was rare in salamander populations having small hatch-timing variation, but was frequent in those having large hatch-timing variation. Thus, giant salamander cannibals occurred only in the latter. We clearly showed that salamander giants exerted strong predation pressure on frog tadpoles, which induced large behavioral and morphological defenses in the tadpoles and caused them to metamorphose late at large size. Hence, predator cannibalism arising from large variation in the timing

  2. Characterizing the Leaching Behavior of Coal Combustion Residues using the Leaching Environmental Assessment Framework (LEAF) to Inform Future Management Decisions

    EPA Science Inventory

    Abstract for presentation on Characterizing the Leaching Behavior of Coal Combustion Residues using the Leaching Environmental Assessment Framework (LEAF) to Inform Future Management Decisions. The abstract is attached.

  3. How predation can slow, stop or reverse a prey invasion.

    PubMed

    Owen, M R; Lewis, M A

    2001-07-01

    Observations on Mount St Helens indicate that the spread of recolonizing lupin plants has been slowed due to the presence of insect herbivores and it is possible that the spread of lupins could be reversed in the future by intense insect herbivory [Fagan, W. F. and J. Bishop (2000). Trophic interactions during primary sucession: herbivores slow a plant reinvasion at Mount St. Helens. Amer. Nat. 155, 238-251]. In this paper we investigate mechanisms by which herbivory can contain the spatial spread of recolonizing plants. Our approach is to analyse a series of predator-prey reaction-diffusion models and spatially coupled ordinary differential equation models to derive conditions under which predation pressure can slow, stall or reverse a spatial invasion of prey. We focus on models where prey disperse more slowly than predators. We comment on the types of functional response which give such solutions, and the circumstances under which the models are appropriate. PMID:11497163

  4. Promoting "Healthy Futures" to Reduce Risk Behaviors in Urban Youth: A Randomized Controlled Trial.

    PubMed

    Lindstrom Johnson, Sarah; Jones, Vanya; Cheng, Tina L

    2015-09-01

    There is increasing evidence of the interconnection between educational and health outcomes. Unfortunately wide disparities exist by both socioeconomic status and race/ethnicity in educational and vocational success. This study sought to promote urban youths' career readiness as a way to reduce involvement in risk behaviors. Two hundred primarily African-American youth (ages 14-21) were recruited from a pediatric primary care clinic. Youth randomized to the intervention received three motivational interviewing sessions focused around expectations and planning for the future. Baseline and 6-month follow-up assessments included measures of career readiness and risk behavior involvement (i.e., physical fighting, alcohol and marijuana use). At 6-months, youth randomized to the intervention condition showed increased confidence in their ability to perform the behaviors needed to reach their college/career goals. Additionally, youth randomized to the intervention arm showed decreased fighting behavior (adjusted rate ratio: .27) and marijuana use (adjusted rate ratio: .61). Assisting urban youth in thinking and planning about their future holds promise as a way to reduce their involvement in risk behaviors. This study also demonstrated that motivational interviewing could be used to promote positive behaviors (i.e., career readiness). PMID:26122751

  5. Predatory fish select for coordinated collective motion in virtual prey.

    PubMed

    Ioannou, C C; Guttal, V; Couzin, I D

    2012-09-01

    Movement in animal groups is highly varied and ranges from seemingly disordered motion in swarms to coordinated aligned motion in flocks and schools. These social interactions are often thought to reduce risk from predators, despite a lack of direct evidence. We investigated risk-related selection for collective motion by allowing real predators (bluegill sunfish) to hunt mobile virtual prey. By fusing simulated and real animal behavior, we isolated predator effects while controlling for confounding factors. Prey with a tendency to be attracted toward, and to align direction of travel with, near neighbors tended to form mobile coordinated groups and were rarely attacked. These results demonstrate that collective motion could evolve as a response to predation, without prey being able to detect and respond to predators. PMID:22903520

  6. Prey Capture Ecology of the Cubozoan Carukia barnesi

    PubMed Central

    Sachlikidis, Nik; Jones, Rhondda

    2015-01-01

    Adult Carukia barnesi medusae feed predominantly on larval fish; however, their mode of prey capture seems more complex than previously described. Our findings revealed that during light conditions, this species extends its tentacles and ‘twitches’ them frequently. This highlights the lure-like nematocyst clusters in the water column, which actively attract larval fish that are consequently stung and consumed. This fishing behavior was not observed during dark conditions, presumably to reduce energy expenditure when they are not luring visually oriented prey. We found that larger medusae have longer tentacles; however, the spacing between the nematocyst clusters is not dependent on size, suggesting that the spacing of the nematocyst clusters is important for prey capture. Additionally, larger specimens twitch their tentacles more frequently than small specimens, which correlate with their recent ontogenetic prey shift from plankton to larval fish. These results indicate that adult medusae of C. barnesi are not opportunistically grazing in the water column, but instead utilize sophisticated prey capture techniques to specifically target larval fish. PMID:25970583

  7. Prey Capture Ecology of the Cubozoan Carukia barnesi.

    PubMed

    Courtney, Robert; Sachlikidis, Nik; Jones, Rhondda; Seymour, Jamie

    2015-01-01

    Adult Carukia barnesi medusae feed predominantly on larval fish; however, their mode of prey capture seems more complex than previously described. Our findings revealed that during light conditions, this species extends its tentacles and 'twitches' them frequently. This highlights the lure-like nematocyst clusters in the water column, which actively attract larval fish that are consequently stung and consumed. This fishing behavior was not observed during dark conditions, presumably to reduce energy expenditure when they are not luring visually oriented prey. We found that larger medusae have longer tentacles; however, the spacing between the nematocyst clusters is not dependent on size, suggesting that the spacing of the nematocyst clusters is important for prey capture. Additionally, larger specimens twitch their tentacles more frequently than small specimens, which correlate with their recent ontogenetic prey shift from plankton to larval fish. These results indicate that adult medusae of C. barnesi are not opportunistically grazing in the water column, but instead utilize sophisticated prey capture techniques to specifically target larval fish. PMID:25970583

  8. Tigers and their prey: Predicting carnivore densities from prey abundance

    USGS Publications Warehouse

    Karanth, K.U.; Nichols, J.D.; Kumar, N.S.; Link, W.A.; Hines, J.E.

    2004-01-01

    The goal of ecology is to understand interactions that determine the distribution and abundance of organisms. In principle, ecologists should be able to identify a small number of limiting resources for a species of interest, estimate densities of these resources at different locations across the landscape, and then use these estimates to predict the density of the focal species at these locations. In practice, however, development of functional relationships between abundances of species and their resources has proven extremely difficult, and examples of such predictive ability are very rare. Ecological studies of prey requirements of tigers Panthera tigris led us to develop a simple mechanistic model for predicting tiger density as a function of prey density. We tested our model using data from a landscape-scale long-term (1995-2003) field study that estimated tiger and prey densities in 11 ecologically diverse sites across India. We used field techniques and analytical methods that specifically addressed sampling and detectability, two issues that frequently present problems in macroecological studies of animal populations. Estimated densities of ungulate prey ranged between 5.3 and 63.8 animals per km2. Estimated tiger densities (3.2-16.8 tigers per 100 km2) were reasonably consistent with model predictions. The results provide evidence of a functional relationship between abundances of large carnivores and their prey under a wide range of ecological conditions. In addition to generating important insights into carnivore ecology and conservation, the study provides a potentially useful model for the rigorous conduct of macroecological science.

  9. Degraded environments alter prey risk assessment.

    PubMed

    Lönnstedt, Oona M; McCormick, Mark I; Chivers, Douglas P

    2012-01-01

    Elevated water temperatures, a decrease in ocean pH, and an increasing prevalence of severe storms have lead to bleaching and death of the hard corals that underpin coral reef ecosystems. As coral cover declines, fish diversity and abundance declines. How degradation of coral reefs affects behavior of reef inhabitants is unknown. Here, we demonstrate that risk assessment behaviors of prey are severely affected by coral degradation. Juvenile damselfish were exposed to visual and olfactory indicators of predation risk in healthy live, thermally bleached, and dead coral in a series of laboratory and field experiments. While fish still responded to visual cues in all habitats, they did not respond to olfactory indicators of risk in dead coral habitats, likely as a result of alteration or degradation of chemical cues. These cues are critical for learning and avoiding predators, and a failure to respond can have dramatic repercussions for survival and recruitment. PMID:23403754

  10. Some reflections on 25 years of the association for behavior analysis: Past, present, and future.

    PubMed

    Morris, E K; Baer, D M; Favell, J E; Glenn, S S; Hineline, P N; Malott, M E; Michael, J

    2001-01-01

    This paper offers some reflections on the discipline and profession of behavior analysis, as well as on the Association for Behavior Analysis (ABA), on the occasion of the association's 25th anniversary. It is based on a panel session conducted at the 1999 convention that included six past presidents of ABA (Donald M. Baer, Judith E. Favell, Sigrid S. Glenn, Philip N. Hineline, Jack Michael, and Edward K. Morris) and its current Executive Director and Secretary-Treasurer (Maria E. Malott). Among the topics addressed were (a) the survival of behavior analysis in university and cultural contexts, (b) the training of behavior-analytic researchers and practitioners, (c) relations between basic and applied research, (d) convergences between behavior analysis and other disciplines, (e) the structure and function of ABA, and (f) the importance of students for the future of the association, the discipline, and the profession. Questions from the audience raised issues concerning the relevance of major behavior-analytic journals, advances in behavior analysis since the death of B. F. Skinner, and the availability of accessible, popular material on applied behavior analysis. PMID:22478359

  11. Some reflections on 25 years of the association for behavior analysis: Past, present, and future

    PubMed Central

    Morris, Edward K.; Baer, Donald M.; Favell, Judith E.; Glenn, Sigrid S.; Hineline, Philip N.; Malott, Maria E.; Michael, Jack

    2001-01-01

    This paper offers some reflections on the discipline and profession of behavior analysis, as well as on the Association for Behavior Analysis (ABA), on the occasion of the association's 25th anniversary. It is based on a panel session conducted at the 1999 convention that included six past presidents of ABA (Donald M. Baer, Judith E. Favell, Sigrid S. Glenn, Philip N. Hineline, Jack Michael, and Edward K. Morris) and its current Executive Director and Secretary-Treasurer (Maria E. Malott). Among the topics addressed were (a) the survival of behavior analysis in university and cultural contexts, (b) the training of behavior-analytic researchers and practitioners, (c) relations between basic and applied research, (d) convergences between behavior analysis and other disciplines, (e) the structure and function of ABA, and (f) the importance of students for the future of the association, the discipline, and the profession. Questions from the audience raised issues concerning the relevance of major behavior-analytic journals, advances in behavior analysis since the death of B. F. Skinner, and the availability of accessible, popular material on applied behavior analysis. PMID:22478359

  12. Competing Conservation Objectives for Predators and Prey: Estimating Killer Whale Prey Requirements for Chinook Salmon

    PubMed Central

    Williams, Rob; Krkošek, Martin; Ashe, Erin; Branch, Trevor A.; Clark, Steve; Hammond, Philip S.; Hoyt, Erich; Noren, Dawn P.; Rosen, David; Winship, Arliss

    2011-01-01

    Ecosystem-based management (EBM) of marine resources attempts to conserve interacting species. In contrast to single-species fisheries management, EBM aims to identify and resolve conflicting objectives for different species. Such a conflict may be emerging in the northeastern Pacific for southern resident killer whales (Orcinus orca) and their primary prey, Chinook salmon (Oncorhynchus tshawytscha). Both species have at-risk conservation status and transboundary (Canada–US) ranges. We modeled individual killer whale prey requirements from feeding and growth records of captive killer whales and morphometric data from historic live-capture fishery and whaling records worldwide. The models, combined with caloric value of salmon, and demographic and diet data for wild killer whales, allow us to predict salmon quantities needed to maintain and recover this killer whale population, which numbered 87 individuals in 2009. Our analyses provide new information on cost of lactation and new parameter estimates for other killer whale populations globally. Prey requirements of southern resident killer whales are difficult to reconcile with fisheries and conservation objectives for Chinook salmon, because the number of fish required is large relative to annual returns and fishery catches. For instance, a U.S. recovery goal (2.3% annual population growth of killer whales over 28 years) implies a 75% increase in energetic requirements. Reducing salmon fisheries may serve as a temporary mitigation measure to allow time for management actions to improve salmon productivity to take effect. As ecosystem-based fishery management becomes more prevalent, trade-offs between conservation objectives for predators and prey will become increasingly necessary. Our approach offers scenarios to compare relative influence of various sources of uncertainty on the resulting consumption estimates to prioritise future research efforts, and a general approach for assessing the extent of conflict

  13. Competing conservation objectives for predators and prey: estimating killer whale prey requirements for Chinook salmon.

    PubMed

    Williams, Rob; Krkošek, Martin; Ashe, Erin; Branch, Trevor A; Clark, Steve; Hammond, Philip S; Hoyt, Erich; Noren, Dawn P; Rosen, David; Winship, Arliss

    2011-01-01

    Ecosystem-based management (EBM) of marine resources attempts to conserve interacting species. In contrast to single-species fisheries management, EBM aims to identify and resolve conflicting objectives for different species. Such a conflict may be emerging in the northeastern Pacific for southern resident killer whales (Orcinus orca) and their primary prey, Chinook salmon (Oncorhynchus tshawytscha). Both species have at-risk conservation status and transboundary (Canada-US) ranges. We modeled individual killer whale prey requirements from feeding and growth records of captive killer whales and morphometric data from historic live-capture fishery and whaling records worldwide. The models, combined with caloric value of salmon, and demographic and diet data for wild killer whales, allow us to predict salmon quantities needed to maintain and recover this killer whale population, which numbered 87 individuals in 2009. Our analyses provide new information on cost of lactation and new parameter estimates for other killer whale populations globally. Prey requirements of southern resident killer whales are difficult to reconcile with fisheries and conservation objectives for Chinook salmon, because the number of fish required is large relative to annual returns and fishery catches. For instance, a U.S. recovery goal (2.3% annual population growth of killer whales over 28 years) implies a 75% increase in energetic requirements. Reducing salmon fisheries may serve as a temporary mitigation measure to allow time for management actions to improve salmon productivity to take effect. As ecosystem-based fishery management becomes more prevalent, trade-offs between conservation objectives for predators and prey will become increasingly necessary. Our approach offers scenarios to compare relative influence of various sources of uncertainty on the resulting consumption estimates to prioritise future research efforts, and a general approach for assessing the extent of conflict

  14. Designing serious video games for health behavior change: current status and future directions.

    PubMed

    Thompson, Debbe

    2012-07-01

    Serious video games for health are designed to entertain while changing a specific health behavior. This article identifies behavioral principles that can guide the development of serious video games focused on changing a variety of health behaviors, including those attempting to decrease risk of obesity and type 2 diabetes. Guidelines discussed include how to develop video games that provide a solid foundation for behavior change by enhancing a player's knowledge and skill, ways in which personal mastery experiences can be incorporated into a video game environment, using game characters and avatars to promote observational learning, creating personalized experiences through tailoring, and the importance of achieving a balance between "fun-ness" and "seriousness." The article concludes with suggestions for future research needed to inform this rapidly growing field. PMID:22920806

  15. Designing Serious Video Games for Health Behavior Change: Current Status and Future Directions

    PubMed Central

    Thompson, Debbe

    2012-01-01

    Serious video games for health are designed to entertain while changing a specific health behavior. This article identifies behavioral principles that can guide the development of serious video games focused on changing a variety of health behaviors, including those attempting to decrease risk of obesity and type 2 diabetes. Guidelines discussed include how to develop video games that provide a solid foundation for behavior change by enhancing a player’s knowledge and skill, ways in which personal mastery experiences can be incorporated into a video game environment, using game characters and avatars to promote observational learning, creating personalized experiences through tailoring, and the importance of achieving a balance between “fun-ness” and “seriousness.” The article concludes with suggestions for future research needed to inform this rapidly growing field. PMID:22920806

  16. Hunting strategies in wild common marmosets are prey and age dependent.

    PubMed

    Schiel, Nicola; Souto, Antonio; Huber, Ludwig; Bezerra, Bruna M

    2010-12-01

    We investigated the hunting strategies of wild common marmosets (Callithrix jacchus) to determine whether the strategies differed among animals of different age classes and/or prey type. The study was conducted in a fragment of Atlantic Rain Forest, situated 40 km from Recife (PE/Brazil). Twenty-seven individuals from four social groups were observed. Captured prey items were divided into three categories. The hunting strategies of the common marmosets were ranked into four categories. The acquisition of larger prey (items more than 2.0 cm) involved the appropriate body movements and postures that concealed the approaching marmosets, whereas the acquisition of smaller prey (items under 2.0 cm) involved less concealing behaviors. Furthermore, adults and juveniles (age ≥ 5 months) were more capable of capturing larger prey than were younger (1-2 months) or older infants (3-4 months). Although older infants were successful in capturing certain prey, they often failed when they attempted to capture larger prey that jumped and/or used flight to escape. The results suggest that both the experience of the monkeys and escape behavior of the prey affect predation efficiency in wild common marmosets. PMID:20623501

  17. Foraging efficiency of a predator flock for randomly moving prey: A simulation study

    NASA Astrophysics Data System (ADS)

    Lee, Sang-Hee; Kwon, Ohsung

    2016-03-01

    Flocking behavior of animals is highly advantageous for taking food resources. The degree of the advantage is related to the ability of flock members to detect their prey and the mobility of prey individuals. In this study, to explore the relation, we constructed a model to simulate a predator flock and its randomly moving prey. The predator members have the prey detection ability, which was characterized as sensing distance, R, and a sensing angle, θ. The mobility of the prey individuals was characterized as the maximum traveling distance of an iteration time step, L. The relative flock foraging efficiency, ɛ, was defined as ɛ = 1 ‑ (Td/Tup). Tup and Td represent the spent time for the flock to eat all prey individuals and to uptake the last remaining 10% prey, respectively. Simulation results showed that ɛ increased, maximized, and decreased with the increase of R, regardless of L. As the number of prey, N, increased, the tendency of the increasing and decreasing was diluted. The result was briefly discussed in relation to the flock foraging behavior and the development of the model toward applications for real ecosystems.

  18. Innate prey preference overridden by familiarisation with detrimental prey in a specialised myrmecophagous predator

    NASA Astrophysics Data System (ADS)

    Pekár, Stano; Cárdenas, Manuel

    2015-02-01

    Prey-specialised spiders often do not have brood care and may not deposit eggs in the proximity of the preferred prey. Thus, naïve spiderlings are left to their own to find their focal prey. Our aim was to reveal whether the choice of a specific prey is innate and whether familiarisation with a certain prey will condition prey choice. We used the myrmecophagous spider Euryopis episinoides, which specialises on Messor ants. It finds ants using chemical cues deposited on the substrate. Naïve spiderlings were offered chemical cues from Messor and Myrmica ants and Drosophila flies. They chose significantly more chemical cues from Messor ants than those from Drosophila flies. Then spiderlings were assigned to three prey treatments: fed with Messor ants only (optimal prey), fed with Myrmica ants only (suboptimal prey) or fed with Drosophila flies only (detrimental prey) until adulthood. Every 2 weeks, all spiders from all treatments were offered chemical cues from the three prey types and the frequency of choice and latency to assuming a posture were recorded. Experienced spiderlings preferred chemical cues from the prey in which they were raised. They suffered high mortality on Drosophila flies and attained largest size on the optimal prey. We show here that majority of spiderlings are born with an innate preference to their focal prey, which can be altered by familiarisation with alternative prey, irrespective of whether such a prey is beneficial.

  19. Tie them up tight: wrapping by Philoponella vicina spiders breaks, compresses and sometimes kills their prey

    NASA Astrophysics Data System (ADS)

    Eberhard, William G.; Barrantes, Gilbert; Weng, Ju-Lin

    2006-05-01

    We show that uloborid spiders, which lack the poison glands typical of nearly all other spiders, employ thousands of wrapping movements with their hind legs and up to hundreds of meters of silk line to make a shroud that applies substantial compressive force to their prey. Shrouds sometimes break the prey’s legs, buckle its compound eyes inward, or kill it outright. The compressive force apparently results from the summation of small tensions on sticky lines as they are applied to the prey package. Behavioral details indicate that wrapping is designed to compact prey; in turn, compaction probably functions to facilitate these spiders’ unusual method of feeding. This is the first demonstration that prey wrapping by spiders compacts and physically damages their prey, rather than simply restraining them.

  20. Adult Prey Neutralizes Predator Nonconsumptive Limitation of Prey Recruitment.

    PubMed

    Ellrich, Julius A; Scrosati, Ricardo A; Romoth, Katharina; Molis, Markus

    2016-01-01

    Recent studies have shown that predator chemical cues can limit prey demographic rates such as recruitment. For instance, barnacle pelagic larvae reduce settlement where predatory dogwhelk cues are detected, thereby limiting benthic recruitment. However, adult barnacles attract conspecific larvae through chemical and visual cues, aiding larvae to find suitable habitat for development. Thus, we tested the hypothesis that the presence of adult barnacles (Semibalanus balanoides) can neutralize dogwhelk (Nucella lapillus) nonconsumptive effects on barnacle recruitment. We did a field experiment in Atlantic Canada during the 2012 and 2013 barnacle recruitment seasons (May-June). We manipulated the presence of dogwhelks (without allowing them to physically contact barnacles) and adult barnacles in cages established in rocky intertidal habitats. At the end of both recruitment seasons, we measured barnacle recruit density on tiles kept inside the cages. Without adult barnacles, the nearby presence of dogwhelks limited barnacle recruitment by 51%. However, the presence of adult barnacles increased barnacle recruitment by 44% and neutralized dogwhelk nonconsumptive effects on barnacle recruitment, as recruit density was unaffected by dogwhelk presence. For species from several invertebrate phyla, benthic adult organisms attract conspecific pelagic larvae. Thus, adult prey might commonly constitute a key factor preventing negative predator nonconsumptive effects on prey recruitment. PMID:27123994

  1. Adult Prey Neutralizes Predator Nonconsumptive Limitation of Prey Recruitment

    PubMed Central

    Scrosati, Ricardo A.; Romoth, Katharina; Molis, Markus

    2016-01-01

    Recent studies have shown that predator chemical cues can limit prey demographic rates such as recruitment. For instance, barnacle pelagic larvae reduce settlement where predatory dogwhelk cues are detected, thereby limiting benthic recruitment. However, adult barnacles attract conspecific larvae through chemical and visual cues, aiding larvae to find suitable habitat for development. Thus, we tested the hypothesis that the presence of adult barnacles (Semibalanus balanoides) can neutralize dogwhelk (Nucella lapillus) nonconsumptive effects on barnacle recruitment. We did a field experiment in Atlantic Canada during the 2012 and 2013 barnacle recruitment seasons (May–June). We manipulated the presence of dogwhelks (without allowing them to physically contact barnacles) and adult barnacles in cages established in rocky intertidal habitats. At the end of both recruitment seasons, we measured barnacle recruit density on tiles kept inside the cages. Without adult barnacles, the nearby presence of dogwhelks limited barnacle recruitment by 51%. However, the presence of adult barnacles increased barnacle recruitment by 44% and neutralized dogwhelk nonconsumptive effects on barnacle recruitment, as recruit density was unaffected by dogwhelk presence. For species from several invertebrate phyla, benthic adult organisms attract conspecific pelagic larvae. Thus, adult prey might commonly constitute a key factor preventing negative predator nonconsumptive effects on prey recruitment. PMID:27123994

  2. Predaceous diving beetle, Dytiscus sharpi sharpi (Coleoptera: Dytiscidae) larvae avoid cannibalism by recognizing prey.

    PubMed

    Inoda, Toshio

    2012-09-01

    Larvae of diving beetles such as the various Dytiscus species (Coleoptera: Dytiscidae) are carnivorous and usually prey on other aquatic animals. Cannibalism among larvae of Dytiscus sharpi sharpi (Wehncke) was observed to begin when they were starved for more than two days under artificial breeding conditions. However, the 2-day starved larvae did not show cannibalism in the presence of intact, motionless, frozen tadpoles, or frozen shrimps. The beetle larvae attacked and captured intact tadpoles faster (15 sec) than other motionless and frozen tadpoles (120 sec), indicating that prey movement was an important factor in stimulating feeding behavior in larvae. Prey density does not have an effect on larval cannibalism. In cases in which preys are present at lower densities than that of larvae, a group of beetle larvae frequently fed on single prey. This feeding behavior, therefore, provides direct evidence of self-other recognition at the species level. Using two traps in one aquarium that allows the larvae to detect only prey smell, one containing tadpoles and another empty, the beetle larvae were attracted to the trap with tadpoles at high frequency, but not to the empty trap. In another experiment, the beetle larvae were not attracted to the trap containing a beetle larva. These results suggest that the larvae of D. sharpi sharpi are capable of recognizing prey scent, which enables the promotion of foraging behavior and the prevention of cannibalism. PMID:22943777

  3. A Sensory-Driven Trade-Off between Coordinated Motion in Social Prey and a Predator's Visual Confusion.

    PubMed

    Lemasson, Bertrand H; Tanner, Colby J; Dimperio, Eric

    2016-02-01

    Social animals are capable of enhancing their awareness by paying attention to their neighbors, and prey found in groups can also confuse their predators. Both sides of these sensory benefits have long been appreciated, yet less is known of how the perception of events from the perspectives of both prey and predator can interact to influence their encounters. Here we examined how a visual sensory mechanism impacts the collective motion of prey and, subsequently, how their resulting movements influenced predator confusion and capture ability. We presented virtual prey to human players in a targeting game and measured the speed and accuracy with which participants caught designated prey. As prey paid more attention to neighbor movements their collective coordination increased, yet increases in prey coordination were positively associated with increases in the speed and accuracy of attacks. However, while attack speed was unaffected by the initial state of the prey, accuracy dropped significantly if the prey were already organized at the start of the attack, rather than in the process of self-organizing. By repeating attack scenarios and masking the targeted prey's neighbors we were able to visually isolate them and conclusively demonstrate how visual confusion impacted capture ability. Delays in capture caused by decreased coordination amongst the prey depended upon the collection motion of neighboring prey, while it was primarily the motion of the targets themselves that determined capture accuracy. Interestingly, while a complete loss of coordination in the prey (e.g., a flash expansion) caused the greatest delay in capture, such behavior had little effect on capture accuracy. Lastly, while increases in collective coordination in prey enhanced personal risk, traveling in coordinated groups was still better than appearing alone. These findings demonstrate a trade-off between the sensory mechanisms that can enhance the collective properties that emerge in social

  4. When attempts at robbing prey turn fatal

    NASA Astrophysics Data System (ADS)

    Dejean, Alain; Corbara, Bruno; Azémar, Frédéric; Carpenter, James M.

    2012-07-01

    Because group-hunting arboreal ants spread-eagle insect prey for a long time before retrieving them, these prey can be coveted by predatory flying insects. Yet, attempting to rob these prey is risky if the ant species is also an effective predator. Here, we show that trying to rob prey from Azteca andreae workers is a fatal error as 268 out of 276 potential cleptobionts (97.1 %) were captured in turn. The ant workers hunt in a group and use the "Velcro®" principle to cling firmly to the leaves of their host tree, permitting them to capture very large prey. Exceptions were one social wasp, plus some Trigona spp. workers and flies that landed directly on the prey and were able to take off immediately when attacked. We conclude that in this situation, previously captured prey attract potential cleptobionts that are captured in turn in most of the cases.

  5. Density-dependent prey mortality is determined by the spatial scale of predator foraging.

    PubMed

    McCarthy, Erin K; White, J Wilson

    2016-02-01

    Foraging theory predicts which prey patches predators should target. However, in most habitats, what constitutes a 'patch' and how prey density is calculated are subjective concepts and depend on the spatial scale at which the predator (or scientist) is observing. Moreover, the predator's 'foraging scale' affects prey population dynamics: predators should produce directly density-dependent (DDD) prey mortality at the foraging scale, but inversely density-dependent (IDD) mortality (safety-in-numbers) at smaller scales. We performed the first experimental test of these predictions using behavioral assays with guppies (Poecilia reticulata) feeding on bloodworm 'prey' patches. The guppy's foraging scale had already been estimated in a prior study. Our experimental results confirmed theoretical predictions: predation was IDD when prey were aggregated at a scale smaller than the foraging scale, but not when prey were aggregated at larger scales. These results could be used to predict outcomes of predator-prey interactions in continuous, non-discrete habitats in the field. PMID:26116266

  6. Promoting Behavior Change from Alcohol Use through Mobile Technology: The Future of Ecological Momentary Assessment

    PubMed Central

    Cohn, Amy M.; Hunter-Reel, Dorian; Hagman, Brett T.; Mitchell, Jessica

    2011-01-01

    Background Interactive and mobile technologies (i.e., smartphones such as Blackberries, iPhones, and palm-top computers) show promise as an efficacious and cost-effective means of communicating health-behavior risks, improving public health outcomes, and accelerating behavior change (Abroms and Maibach, 2008). The present study was conducted as a “needs assessment” to examine the current available mobile smartphone applications (e.g., apps) that utilize principles of ecological momentary assessment (EMA) -- daily self-monitoring or near real-time self-assessment of alcohol use behavior -- to promote positive behavior change, alcohol harm reduction, psycho-education about alcohol use, or abstinence from alcohol. Methods Data were collected and analyzed from iTunes for Apple iPhone©. An inventory assessed the number of available apps that directly addressed alcohol use and consumption, alcohol treatment, or recovery, and whether these apps incorporated empirically-based components of alcohol treatment. Results Findings showed that few apps addressed alcohol use behavior change or recovery. Aside from tracking drinking consumption, a minority utilized empirically-based components of alcohol treatment. Some apps claimed they could serve as an intervention, however no empirical evidence was provided. Conclusions More studies are needed to examine the efficacy of mobile technology in alcohol intervention studies. The large gap between availability of mobile apps and their use in alcohol treatment programs indicate several important future directions for research. PMID:21689119

  7. The dampening effect of employees’ future orientation on cyberloafing behaviors: the mediating role of self-control

    PubMed Central

    Zhang, Heyun; Zhao, Huanhuan; Liu, Jingxuan; Xu, Yan; Lu, Hui

    2015-01-01

    Previous studies on reducing employees’ cyberloafing behaviors have primarily examined the external control factors but seldomly taken individual internal subjective factors into consideration. Future orientation, an important individual factor, is defined as the extent to which one plans for future time and considers future consequences of one’s current behavior. To explore further whether and how employees’ future orientation can dampen their cyberloafing behaviors, two studies were conducted to examine the relationship between employees’ future orientation and cyberloafing behaviors. The mediation effect of employees’ objective and subjective self-control between them was also examined. In Study 1, a set of questionnaires was completed, and the results revealed that the relationship between employees’ future orientation and cyberloafing behaviors was negative, and objective self-control mediated the relationship. Next, we conducted a priming experiment (Study 2) to examine the causal relationship and psychological mechanism between employees’ future orientation and cyberloafing behaviors. The results demonstrated that employees’ future-orientation dampened their attitudes and intentions to engage in cyberloafing, and subjective self-control mediated this dampening effect. Theoretical and practical implications of these findings are also discussed. PMID:26483735

  8. From Cues to Signals: Evolution of Interspecific Communication via Aposematism and Mimicry in a Predator-Prey System

    PubMed Central

    Lehmann, Kenna D. S.; Goldman, Brian W.; Dworkin, Ian; Bryson, David M.; Wagner, Aaron P.

    2014-01-01

    Current theory suggests that many signaling systems evolved from preexisting cues. In aposematic systems, prey warning signals benefit both predator and prey. When the signal is highly beneficial, a third species often evolves to mimic the toxic species, exploiting the signaling system for its own protection. We investigated the evolutionary dynamics of predator cue utilization and prey signaling in a digital predator-prey system in which prey could evolve to alter their appearance to mimic poison-free or poisonous prey. In predators, we observed rapid evolution of cue recognition (i.e. active behavioral responses) when presented with sufficiently poisonous prey. In addition, active signaling (i.e. mimicry) evolved in prey under all conditions that led to cue utilization. Thus we show that despite imperfect and dishonest signaling, given a high cost of consuming poisonous prey, complex systems of interspecific communication can evolve via predator cue recognition and prey signal manipulation. This provides evidence supporting hypotheses that cues may serve as stepping-stones in the evolution of more advanced communication and signaling systems that incorporate information about the environment. PMID:24614755

  9. The Many Faces of Fear: Comparing the Pathways and Impacts of Nonconsumptive Predator Effects on Prey Populations

    PubMed Central

    Preisser, Evan L.; Bolnick, Daniel I.

    2008-01-01

    Background Most ecological models assume that predator and prey populations interact solely through consumption: predators reduce prey densities by killing and consuming individual prey. However, predators can also reduce prey densities by forcing prey to adopt costly defensive strategies. Methodology/Principal Findings We build on a simple Lotka-Volterra predator-prey model to provide a heuristic tool for distinguishing between the demographic effects of consumption (consumptive effects) and of anti-predator defenses (nonconsumptive effects), and for distinguishing among the multiple mechanisms by which anti-predator defenses might reduce prey population growth rates. We illustrate these alternative pathways for nonconsumptive effects with selected empirical examples, and use a meta-analysis of published literature to estimate the mean effect size of each pathway. Overall, predation risk tends to have a much larger impact on prey foraging behavior than measures of growth, survivorship, or fecundity. Conclusions/Significance While our model provides a concise framework for understanding the many potential NCE pathways and their relationships to each other, our results confirm empirical research showing that prey are able to partially compensate for changes in energy income, mitigating the fitness effects of defensive changes in time budgets. Distinguishing the many facets of nonconsumptive effects raises some novel questions, and will help guide both empirical and theoretical studies of how predation risk affects prey dynamics. PMID:18560575

  10. Structuring the Future: Anticipated Life Events, Peer Networks, and Adolescent Sexual Behavior

    PubMed Central

    Soller, Brian; Haynie, Dana L.

    2013-01-01

    While prior research has established associations between individual expectations of future events and risk behavior among adolescents, the potential effects of peers’ future perceptions on risk-taking have been overlooked. We extend prior research by testing whether peers’ anticipation of college completion is associated with adolescent sexual risk-taking. We also examine whether adolescents’ perceptions of the negative consequences of pregnancy and idealized romantic relationship scripts mediate the association between peers’ anticipation of college completion and sexual risk-taking. Results from multivariate regression models with data from the National Longitudinal Study of Adolescent Health (Add Health) indicate peers’ anticipation of college completion is negatively associated with a composite measure of sexual risk-taking and positively associated with the odds of abstaining from sexual intercourse and only engaging in intercourse with a romantic partner (compared to having intercourse with a non-romantic partner). In addition, perceptions of the negative consequences of pregnancy and sexualized relationship scripts appear to mediate a large portion of the association between peers’ anticipation of future success and sexual risk-taking and the likelihood of abstaining (but not engaging in romantic-only intercourse). Results from our study underscore the importance of peers in shaping adolescent sexual behavior. PMID:24223438

  11. Aquatic feeding in pipid frogs: the use of suction for prey capture

    PubMed Central

    Carreño, Carrie A.; Nishikawa, Kiisa C.

    2010-01-01

    Inertial suction feeding is the most common method of prey capture among aquatic vertebrates. However, it had been unclear whether the aquatic frogs in the family Pipidae also used inertial suction for prey capture. In this study, we examined feeding behavior in four species of pipids, Pipa pipa, Xenopus laevis, Hymenochirus boettgeri and Pseudhymenochirus merlini. Pressure in the buccopharyngeal cavity was measured during prey capture. These pressure measurements were coupled with high-speed recordings of feeding behavior. For each species, the internal buccopharyngeal pressure was found to drop significantly below ambient pressure, and changes in pressure corresponded with the onset of mouth opening. Kinematic analysis revealed that all species of pipids generated subambient pressure during prey capture; H. boettgeri and P. merlini relied solely on inertial suction feeding. Pipa pipa and X. laevis additionally employed forelimb scooping during prey capture but both of these species demonstrated the ability to capture prey with inertial suction alone. Based on buccopharyngeal pressure measurements as well as kinematic analyses, we conclude that inertial suction feeding is used during prey capture in these four species of pipids. PMID:20511513

  12. Tiger beetle's pursuit of prey depends on distance

    NASA Astrophysics Data System (ADS)

    Noest, Robert; Wang, Jane

    2015-03-01

    Tiger beetles are fast predators capable of chasing prey under closed-loop visual guidance. We investigated their control system using high-speed digital recordings of beetles chasing a moving prey dummy in a laboratory arena. Analysis reveals that the beetle uses a proportional control law in which the angular position of the prey relative to the beetle's body axis drives the beetle's angular velocity with a delay of about 28 ms. The system gain is shown to depend on the beetle-prey distance in a pattern indicating three hunting phases over the observed distance domain. We show that to explain this behavior the tiger beetle must be capable of visually determining the distance to its target and using that to adapt the gain in its proportional control law. We will end with a discussion on the possible methods for distance detection by the tiger beetle and focus on two of them. Motion parallax, using the natural head sway induced by the walking gait of the tiger beetle, is shown to have insufficient distance range. However elevation in the field of vision, using the angle with respect to the horizon at which a target is observed, has a much larger distance range and is a prime candidate for the mechanism of visual distance detection in the tiger beetle.

  13. A Sensory-Driven Trade-Off between Coordinated Motion in Social Prey and a Predator’s Visual Confusion

    PubMed Central

    Lemasson, Bertrand H.; Tanner, Colby J.; Dimperio, Eric

    2016-01-01

    Social animals are capable of enhancing their awareness by paying attention to their neighbors, and prey found in groups can also confuse their predators. Both sides of these sensory benefits have long been appreciated, yet less is known of how the perception of events from the perspectives of both prey and predator can interact to influence their encounters. Here we examined how a visual sensory mechanism impacts the collective motion of prey and, subsequently, how their resulting movements influenced predator confusion and capture ability. We presented virtual prey to human players in a targeting game and measured the speed and accuracy with which participants caught designated prey. As prey paid more attention to neighbor movements their collective coordination increased, yet increases in prey coordination were positively associated with increases in the speed and accuracy of attacks. However, while attack speed was unaffected by the initial state of the prey, accuracy dropped significantly if the prey were already organized at the start of the attack, rather than in the process of self-organizing. By repeating attack scenarios and masking the targeted prey’s neighbors we were able to visually isolate them and conclusively demonstrate how visual confusion impacted capture ability. Delays in capture caused by decreased coordination amongst the prey depended upon the collection motion of neighboring prey, while it was primarily the motion of the targets themselves that determined capture accuracy. Interestingly, while a complete loss of coordination in the prey (e.g., a flash expansion) caused the greatest delay in capture, such behavior had little effect on capture accuracy. Lastly, while increases in collective coordination in prey enhanced personal risk, traveling in coordinated groups was still better than appearing alone. These findings demonstrate a trade-off between the sensory mechanisms that can enhance the collective properties that emerge in social

  14. Kinematics of terrestrial capture of prey by the eel-catfish Channallabes apus.

    PubMed

    Van Wassenbergh, Sam

    2013-08-01

    In contrast to numerous studies on the function of the locomotor system used by fishes when moving between water and land, little knowledge is available about the biomechanical requirements to the capture and transport of food by fish in a terrestrial situation. This study focuses on the kinematics of terrestrial capture of prey by the eel-catfish (Channallabes apus: Clariidae), a behavior that was only recently discovered for this species. The analyses show that C. apus inclines its head downward at a significantly steeper angle during terrestrial feeding compared with benthic aquatic feeding. This suggests that placing the jaws above ground-based prey is important for successful prehension by the jaws. The increased inclination of the head resulted from accumulated dorsoventral flexion of the body more than one head-length behind the skull. Alternatively, this posture of the head was assumed by rolling to one side while bending the body laterally. The speed of buccopharyngeal expansion in air versus in water matched the predicted increase by a factor of 3, under the assumption that the velocity of muscular contraction for maximal output of power by C. apus is optimized to operate under a specific hydrodynamic loading, and shifts to an unloaded contraction regime when operating in air. Combining these insights with future studies on other extant amphibious fish species that perform terrestrial feeding may eventually allow us to pinpoint the adaptations to the feeding system that have led to the evolution of a terrestrial lifestyle in tetrapods. PMID:23624865

  15. Insect prey eaten by Hoary Bats (Lasiurus cinereus) prior to fatal collisions with wind turbines

    USGS Publications Warehouse

    Valdez, Ernest W.; Cryan, Paul M.

    2013-01-01

    Wind turbines are being deployed all across the world to meet the growing demand for energy, and in many areas, these turbines are causing the deaths of insectivorous migratory bats. One of the hypothesized causes of bat susceptibility is that bats are attracted to insects on or near the turbines. We examined insect remains in the stomachs and intestines of hoary bats (Lasiurus cinereus) found dead beneath wind turbines in New York and Texas to evaluate the hypothesis that bats die while feeding at turbines. Most of the bats we examined had full stomachs, indicating that they fed in the minutes to hours leading up to their deaths. However, we did not find prey in the mouths or throats of any bats that would indicate the bats died while capturing prey. Hoary bats fed mostly on moths, but we also detected the regular presence of beetles, true bugs, and crickets. Presence of terrestrial insects in stomachs indicates that bats may have gleaned them from the ground or the turbine surfaces, yet aerial capture of winged insect stages cannot be ruled out. Our findings confirm earlier studies that indicate hoary bats feed during migration and eat mostly moths. Future studies on bat behaviors and insect presence at wind turbines could help determine whether feeding at turbines is a major fatality risk for bats.

  16. The Impact of Exposure to Addictive Drugs on Future Generations: Physiological and Behavioral Effects

    PubMed Central

    Vassoler, F.M.; Byrnes, E.M.; Pierce, R.C.

    2013-01-01

    It is clear that both genetic and environmental factors contribute to drug addiction. Recent evidence indicating trans-generational influences of drug abuse highlight potential epigenetic factors as well. Specifically, mounting evidence suggests that parental ingestion of abused drugs influence the physiology and behavior of future generations even in the absence of prenatal exposure. The goal of this review is to describe the trans-generational consequences of preconception exposure to drugs of abuse for five major classes of drugs: alcohol, nicotine, marijuana, opioids, and cocaine. The potential epigenetic mechanisms underlying the transmission of these phenotypes across generations also are detailed. PMID:23810828

  17. The organization and dynamics of corticostriatal pathways link the medial orbitofrontal cortex to future behavioral responses.

    PubMed

    Verstynen, Timothy D

    2014-11-15

    Accurately making a decision in the face of incongruent options increases the efficiency of making similar congruency decisions in the future. Contextual factors like reward can modulate this adaptive process, suggesting that networks associated with monitoring previous success and failure outcomes might contribute to this form of behavioral updating. To evaluate this possibility, a group of healthy adults (n = 30) were tested with functional MRI (fMRI) while they performed a color-word Stroop task. In a conflict-related region of the medial orbitofrontal cortex (mOFC), stronger BOLD responses predicted faster response times (RTs) on the next trial. More importantly, the degree of behavioral adaptation of RTs was correlated with the magnitude of mOFC-RT associations on the previous trial, but only after accounting for network-level interactions with prefrontal and striatal regions. This suggests that congruency sequencing effects may rely on interactions between distributed corticostriatal circuits. This possibility was evaluated by measuring the convergence of white matter projections from frontal areas into the striatum with diffusion-weighted imaging. In these pathways, greater convergence of corticostriatal projections correlated with stronger functional mOFC-RT associations that, in turn, provided an indirect pathway linking anatomical structure to behavior. Thus distributed corticostriatal processing may mediate the orbitofrontal cortex's influence on behavioral updating, even in the absence of explicit rewards. PMID:25143543

  18. Prey transport in "palatine-erecting" elapid snakes.

    PubMed

    Deufel, Alexandra; Cundall, David

    2003-12-01

    Cobras and mambas are members of a group of elapid snakes supposedly united by the morphology and inferred behavior of their palatine bone during prey transport (palatine erectors). The palatine erectors investigated (Dendroaspis polylepis, Naja pallida, Ophiophagus hannah, Aspidelaps scutatus, A. lubricus) show differences in the morphology of their feeding apparatus that do not affect the overall behavior of the system. We delineated the structures directly involved in producing palatine erection during prey transport. Palatine erection can be achieved by a colubroid muscle contraction pattern acting on a palato-pterygoid bar with a movable palato-pterygoid joint and a palatine that is stabilized against the snout. The palatine characters originally proposed to cause palatine erection are not required to produce the behavior and actually impede it in Naja pallida. Palatine-erecting elapids share a fundamental design of the palato-maxillary apparatus with all higher snakes. A set of plesiomorphic core characters is functionally integrated to function in prey transport using the pterygoid walk. Variant characters are either part of a structural periphery unrelated to the core structures that define function or patterns of variation are subordinate character sets operating within functional thresholds of a single system. PMID:14584037

  19. An Unprecedented Role Reversal: Ground Beetle Larvae (Coleoptera: Carabidae) Lure Amphibians and Prey upon Them

    PubMed Central

    Wizen, Gil; Gasith, Avital

    2011-01-01

    Amphibians often feed on beetle larvae, including those of ground beetles (Carabidae). Preliminary reports have detailed an unusual trophic interaction in which, in contrast, larvae of the ground beetle Epomis prey upon juvenile and adult amphibians. While it is known that these larvae feed exclusively on amphibians, how the predator-prey encounter occurs to the advantage of the beetle larvae had been unknown to date. Using laboratory observations and controlled experiments, we recorded the feeding behavior of Epomis larvae, as well as the behavior of their amphibian prey. Here we reveal that larvae of two species of Epomis (E. circumscriptus and E. dejeani) lure their potential predator, taking advantage of the amphibian's predation behavior. The Epomis larva combines a sit-and-wait strategy with unique movements of its antennae and mandibles to draw the attention of the amphibian to the presence of a potential prey. The intensity of this enticement increases with decreasing distance between the larva and the amphibian. When the amphibian attacks, the larva almost always manages to avoid the predator's protracted tongue, exploiting the opportunity to attach itself to the amphibian's body and initiate feeding. Our findings suggest that the trophic interaction between Epomis larvae and amphibians is one of the only natural cases of obligatory predator-prey role reversal. Moreover, this interaction involves a small insect larva that successfully lures and preys on a larger vertebrate. Such role reversal is exceptional in the animal world, extending our perspective of co-evolution in the arms race between predator and prey, and suggesting that counterattack defense behavior has evolved into predator-prey role reversal. PMID:21957480

  20. Spreading and vanishing in the diffusive prey-predator model with a free boundary

    NASA Astrophysics Data System (ADS)

    Wang, Mingxin

    2015-06-01

    This paper deals with the diffusive Lotka-Volterra type prey-predator model with a free boundary over a one dimensional habitat. This problem may be used to describe the interaction between indigenous species and invasive species and the spreading of such two species, with the free boundary representing the expanding front. Our main purpose is to study the spreading and vanishing phenomena and long time behaviors of prey and predator.

  1. Coevolution can reverse predator-prey cycles.

    PubMed

    Cortez, Michael H; Weitz, Joshua S

    2014-05-20

    A hallmark of Lotka-Volterra models, and other ecological models of predator-prey interactions, is that in predator-prey cycles, peaks in prey abundance precede peaks in predator abundance. Such models typically assume that species life history traits are fixed over ecologically relevant time scales. However, the coevolution of predator and prey traits has been shown to alter the community dynamics of natural systems, leading to novel dynamics including antiphase and cryptic cycles. Here, using an eco-coevolutionary model, we show that predator-prey coevolution can also drive population cycles where the opposite of canonical Lotka-Volterra oscillations occurs: predator peaks precede prey peaks. These reversed cycles arise when selection favors extreme phenotypes, predator offense is costly, and prey defense is effective against low-offense predators. We present multiple datasets from phage-cholera, mink-muskrat, and gyrfalcon-rock ptarmigan systems that exhibit reversed-peak ordering. Our results suggest that such cycles are a potential signature of predator-prey coevolution and reveal unique ways in which predator-prey coevolution can shape, and possibly reverse, community dynamics. PMID:24799689

  2. Coevolution can reverse predator–prey cycles

    PubMed Central

    Cortez, Michael H.; Weitz, Joshua S.

    2014-01-01

    A hallmark of Lotka–Volterra models, and other ecological models of predator–prey interactions, is that in predator–prey cycles, peaks in prey abundance precede peaks in predator abundance. Such models typically assume that species life history traits are fixed over ecologically relevant time scales. However, the coevolution of predator and prey traits has been shown to alter the community dynamics of natural systems, leading to novel dynamics including antiphase and cryptic cycles. Here, using an eco-coevolutionary model, we show that predator–prey coevolution can also drive population cycles where the opposite of canonical Lotka–Volterra oscillations occurs: predator peaks precede prey peaks. These reversed cycles arise when selection favors extreme phenotypes, predator offense is costly, and prey defense is effective against low-offense predators. We present multiple datasets from phage–cholera, mink–muskrat, and gyrfalcon–rock ptarmigan systems that exhibit reversed-peak ordering. Our results suggest that such cycles are a potential signature of predator–prey coevolution and reveal unique ways in which predator–prey coevolution can shape, and possibly reverse, community dynamics. PMID:24799689

  3. Theory of Arachnid Prey Localization

    NASA Astrophysics Data System (ADS)

    Stürzl, W.; Kempter, R.; van Hemmen, J. L.

    2000-06-01

    Sand scorpions and many other arachnids locate their prey through highly sensitive slit sensilla at the tips (tarsi) of their eight legs. This sensor array responds to vibrations with stimulus-locked action potentials encoding the target direction. We present a neuronal model to account for stimulus angle determination using a population of second-order neurons, each receiving excitatory input from one tarsus and inhibition from a triad opposite to it. The input opens a time window whose width determines a neuron's firing probability. Stochastic optimization is realized through tuning the balance between excitation and inhibition. The agreement with experiments on the sand scorpion is excellent.

  4. Deterministic and Stochastic Analysis of a Prey-Dependent Predator-Prey System

    ERIC Educational Resources Information Center

    Maiti, Alakes; Samanta, G. P.

    2005-01-01

    This paper reports on studies of the deterministic and stochastic behaviours of a predator-prey system with prey-dependent response function. The first part of the paper deals with the deterministic analysis of uniform boundedness, permanence, stability and bifurcation. In the second part the reproductive and mortality factors of the prey and…

  5. Controllability and Optimal Harvesting of a Prey-Predator Model Incorporating a Prey Refuge

    ERIC Educational Resources Information Center

    Kar, Tapan Kumar

    2006-01-01

    This paper deals with a prey-predator model incorporating a prey refuge and harvesting of the predator species. A mathematical analysis shows that prey refuge plays a crucial role for the survival of the species and that the harvesting effort on the predator may be used as a control to prevent the cyclic behaviour of the system. The optimal…

  6. Effect of a protection zone in the diffusive Leslie predator-prey model

    NASA Astrophysics Data System (ADS)

    Du, Yihong; Peng, Rui; Wang, Mingxin

    In this paper, we consider the diffusive Leslie predator-prey model with large intrinsic predator growth rate, and investigate the change of behavior of the model when a simple protection zone Ω for the prey is introduced. As in earlier work [Y. Du, J. Shi, A diffusive predator-prey model with a protection zone, J. Differential Equations 229 (2006) 63-91; Y. Du, X. Liang, A diffusive competition model with a protection zone, J. Differential Equations 244 (2008) 61-86] we show the existence of a critical patch size of the protection zone, determined by the first Dirichlet eigenvalue of the Laplacian over Ω and the intrinsic growth rate of the prey, so that there is fundamental change of the dynamical behavior of the model only when Ω is above the critical patch size. However, our research here reveals significant difference of the model's behavior from the predator-prey model studied in [Y. Du, J. Shi, A diffusive predator-prey model with a protection zone, J. Differential Equations 229 (2006) 63-91] with the same kind of protection zone. We show that the asymptotic profile of the population distribution of the Leslie model is governed by a standard boundary blow-up problem, and classical or degenerate logistic equations.

  7. Sensory basis for detection of benthic prey in two Lake Malawi cichlids.

    PubMed

    Schwalbe, Margot A B; Webb, Jacqueline F

    2014-04-01

    The adaptive radiations of African cichlids resulted in a diversity of feeding morphologies and strategies, but the role of sensory biology in prey detection and feeding ecology remains largely unexplored. Two endemic Lake Malawi cichlid genera, Tramitichromis and Aulonocara, feed on benthic invertebrates, but differ in lateral line morphology (narrow and widened lateral line canals, respectively) and foraging strategy. The hypothesis that they use their lateral line systems differently was tested by looking at the relative contribution of the lateral line system and vision in prey detection by Tramitichromis sp. and comparing results to those from a complementary study using Aulonocara stuartgranti (Schwalbe et al., 2012). First, behavioral trials were used to assess the ability of Tramitichromis sp. to detect live (mobile) and dead (immobile) benthic prey under light and dark conditions. Second, trials were run before, immediately after, and several weeks after chemical ablation of the lateral line system to determine its role in feeding behavior. Results show that Tramitichromis sp. is a visual predator that neither locates prey in the dark nor depends on lateral line input for prey detection and is thus distinct from A. stuartgranti, which uses its lateral line or a combination of vision and lateral line to detect prey depending on light condition. Investigating how functionally distinctive differences in sensory morphology are correlated with feeding behavior in the laboratory and determining the role of sensory systems in feeding ecology will provide insights into how sensory capabilities may contribute to trophic niche segregation. PMID:24369759

  8. The Relationship between Adolescents' Civic Knowledge, Civic Attitude, and Civic Behavior and Their Self-Reported Future Likelihood of Voting

    ERIC Educational Resources Information Center

    Cohen, Alison K.; Chaffee, Benjamin W.

    2013-01-01

    A long-standing objective of American public education is fostering civically engaged youth. Identifying characteristics associated with likelihood of future voting, a measure of democratic participation that predicts future voting behavior, might yield targets for education programs to increase civic participation. Survey data from urban…

  9. Coexistence in a predator-prey system

    NASA Astrophysics Data System (ADS)

    Droz, Michel; Pȩkalski, Andrzej

    2001-05-01

    We propose a lattice model of two populations, predators and prey. The model is solved via Monte Carlo simulations. Each species moves randomly on the lattice and can live only a certain time without eating. The lattice cells are either grass (eaten by prey) or tree (giving cover for prey). Each animal has a reserve of food that is increased by eating (prey or grass) and decreased after each Monte Carlo step. To breed, a pair of animals must be adjacent and have a certain minimum of food supply. The number of offspring produced depends on the number of available empty sites. We show that such a predator-prey system may finally reach one of the following three steady states: coexisting, with predators and prey; pure prey; or an empty one, in which both populations become extinct. We demonstrate that the probability of arriving at one of the above states depends on the initial densities of the prey and predator populations, the amount of cover, and the way it is spatially distributed.

  10. The relationship between adolescents' civic knowledge, civic attitude, and civic behavior and their self-reported future likelihood of voting

    PubMed Central

    Cohen, Alison K.; Chaffee, Benjamin W.

    2014-01-01

    A long-standing objective of American public education is fostering civically engaged youth. Identifying characteristics associated with likelihood of future voting, a measure of democratic participation that predicts future voting behavior, might yield targets for education programs to increase civic participation. Survey data from urban adolescents were analyzed to elucidate how civic knowledge, civic attitudes, and civic behaviors are associated with self-reported likelihood of future voting. In a multivariable ordered logistic regression model with latent constructs for civic knowledge, attitudes, and behavior, two civic knowledge constructs and two civic attitude constructs maintained a positive, statistically significant independent association with future voting likelihood after adjusting for race/ethnicity and advanced coursework: knowledge of American governance, current events knowledge, general self-efficacy, and skill-specific self-efficacy. Further research is necessary to determine whether education programs can intervene upon these civic knowledge and civic attitude factors to increase voting participation later in life. PMID:24847376

  11. Complex dynamics in a prey predator system with multiple delays

    NASA Astrophysics Data System (ADS)

    Gakkhar, Sunita; Singh, Anuraj

    2012-02-01

    The complex dynamics is explored in a prey predator system with multiple delays. Holling type-II functional response is assumed for prey dynamics. The predator dynamics is governed by modified Leslie-Gower scheme. The existence of periodic solutions via Hopf-bifurcation with respect to both delays are established. An algorithm is developed for drawing two-parametric bifurcation diagram with respect to two delays. The domain of stability with respect to τ1 and τ2 is thus obtained. The complex dynamical behavior of the system outside the domain of stability is evident from the exhaustive numerical simulation. Direction and stability of periodic solutions are also determined using normal form theory and center manifold argument.

  12. Predator fitness increases with selectivity for odd prey.

    PubMed

    Rutz, Christian

    2012-05-01

    The fundamental currency of normative models of animal decision making is Darwinian fitness. In foraging ecology, empirical studies typically assess foraging strategies by recording energy intake rates rather than realized reproductive performance. This study provides a rare empirical link, in a vertebrate predator-prey system, between a predator's foraging behavior and direct measures of its reproductive fitness. Goshawks Accipiter gentilis selectively kill rare color variants of their principal prey, the feral pigeon Columba livia, presumably because targeting odd-looking birds in large uniform flocks helps them overcome confusion effects and enhances attack success. Reproductive performance of individual hawks increases significantly with their selectivity for odd-colored pigeons, even after controlling for confounding age effects. Older hawks exhibit more pronounced dietary preferences, suggesting that hunting performance improves with experience. Intriguingly, although negative frequency-dependent predation by hawks exerts strong selection against rare pigeon phenotypes, pigeon color polymorphism is maintained through negative assortative mating. PMID:22503502

  13. Do the antipredator strategies of shared prey mediate intraguild predation and mesopredator suppression?

    PubMed

    Clare, John D J; Linden, Daniel W; Anderson, Eric M; MacFarland, David M

    2016-06-01

    Understanding the conditions that facilitate top predator effects upon mesopredators and prey is critical for predicting where these effects will be significant. Intraguild predation (IGP) and the ecology of fear are hypotheses used to describe the effects of top predators upon mesopredators and prey species, but make different assumptions about organismal space use. The IGP hypothesis predicts that mesopredator resource acquisition and risk are positively correlated, creating a fitness deficit. But if shared prey also avoid a top predator, then mesopredators may not have to choose between risk and reward. Prey life history may be a critical predictor of how shared prey respond to predation and may mediate mesopredator suppression. We used hierarchical models of species distribution and abundance to test expectations of IGP using two separate triangular relationships between a large carnivore, smaller intraguild carnivore, and shared mammalian prey with different life histories. Following IGP, we expected that a larger carnivore would suppress a smaller carnivore if the shared prey species did not spatially avoid the large carnivore at broad scales. If prey were fearful over broad scales, we expected less evidence of mesopredator suppression. We tested these theoretical hypotheses using remote camera detections across a large spatial extent. Lagomorphs did not appear to avoid coyotes, and fox detection probability was lower as coyote abundance increased. In contrast, white-tailed deer appeared to avoid areas of increased wolf use, and coyote detection probability was not reduced at sites where wolves occurred. These findings suggest that mesopredator suppression by larger carnivores may depend upon the behavior of shared prey, specifically the spatial scale at which they perceive risk. We further discuss how extrinsic environmental factors may contribute to mesopredator suppression. PMID:27239266

  14. Relative Preference and Localized Food Affect Predator Space Use and Consumption of Incidental Prey

    PubMed Central

    Schartel, Tyler E.; Schauber, Eric M.

    2016-01-01

    Abundant, localized foods can concentrate predators and their foraging efforts, thus altering both the spatial distribution of predation risk and predator preferences for prey that are encountered incidentally. However, few investigations have quantified the spatial scale over which localized foods affect predator foraging behavior and consumption of incidental prey. In spring 2010, we experimentally tested how point-source foods altered how generalist predators (white-footed mice, Peromyscus leucopus) utilized space and depredated two incidental prey items: almonds (Prunus dulcis; highly profitable) and maple seeds (Acer saccharum; less profitable). We estimated mouse population densities with trapping webs, quantified mouse consumption rates of these incidental prey items, and measured local mouse activity with track plates. We predicted that 1) mouse activity would be elevated near full feeders, but depressed at intermediate distances from the feeder, 2) consumption of both incidental prey would be high near feeders providing less-preferred food and, 3) consumption of incidental prey would be contingent on predator preference for prey relative to feeders providing more-preferred food. Mouse densities increased significantly from pre- to post-experiment. Mean mouse activity was unexpectedly greatest in control treatments, particularly <15 m from the control (empty) feeder. Feeders with highly preferred food (sunflower seeds) created localized refuges for incidental prey at intermediate distances (15 to 25m) from the feeder. Feeders with less-preferred food (corn) generated localized high risk for highly preferred almonds <10 m of the feeder. Our findings highlight the contingent but predictable effects of locally abundant food on risk experienced by incidental prey, which can be positive or negative depending on both spatial proximity and relative preference. PMID:26978659

  15. Relative Preference and Localized Food Affect Predator Space Use and Consumption of Incidental Prey.

    PubMed

    Schartel, Tyler E; Schauber, Eric M

    2016-01-01

    Abundant, localized foods can concentrate predators and their foraging efforts, thus altering both the spatial distribution of predation risk and predator preferences for prey that are encountered incidentally. However, few investigations have quantified the spatial scale over which localized foods affect predator foraging behavior and consumption of incidental prey. In spring 2010, we experimentally tested how point-source foods altered how generalist predators (white-footed mice, Peromyscus leucopus) utilized space and depredated two incidental prey items: almonds (Prunus dulcis; highly profitable) and maple seeds (Acer saccharum; less profitable). We estimated mouse population densities with trapping webs, quantified mouse consumption rates of these incidental prey items, and measured local mouse activity with track plates. We predicted that 1) mouse activity would be elevated near full feeders, but depressed at intermediate distances from the feeder, 2) consumption of both incidental prey would be high near feeders providing less-preferred food and, 3) consumption of incidental prey would be contingent on predator preference for prey relative to feeders providing more-preferred food. Mouse densities increased significantly from pre- to post-experiment. Mean mouse activity was unexpectedly greatest in control treatments, particularly <15 m from the control (empty) feeder. Feeders with highly preferred food (sunflower seeds) created localized refuges for incidental prey at intermediate distances (15 to 25m) from the feeder. Feeders with less-preferred food (corn) generated localized high risk for highly preferred almonds <10 m of the feeder. Our findings highlight the contingent but predictable effects of locally abundant food on risk experienced by incidental prey, which can be positive or negative depending on both spatial proximity and relative preference. PMID:26978659

  16. Future asymptotic behavior of three-dimensional spacetimes with massive particles

    NASA Astrophysics Data System (ADS)

    Fajman, David

    2016-06-01

    We consider non-vacuum initial data for the three-dimensional Einstein equations coupled to Vlasov matter composed of massive particles, on an arbitrary compact Cauchy hypersurface without boundary. We show that conservation of the total mass implies future completeness of the corresponding maximal development in the isotropic case, independent of the topology. This behavior is fundamentally different from the vacuum case and also from the same model in higher dimensions. In particular, we find that a positive mass of particles in three dimensions avoids recollapse of the spatial geometry. Finally, we construct similar solutions for the Einstein-dust system and describe to what extent the construction fails for massless matter models.

  17. Prey and Pollen Food Choice Depends on Previous Diet in an Omnivorous Predatory Mite.

    PubMed

    Schuldiner-Harpaz, Tarryn; Coll, Moshe; Weintraub, Phyllis G

    2016-08-01

    The time allocated by omnivorous predators to consuming prey versus plant-provided foods (e.g., pollen) directly influences their efficacy as biocontrol agents of agricultural pests. Nonetheless, diet shifting between these two very different food sources remains poorly understood. We hypothesized that previous diet composition influences subsequent choice of prey and plant food types. We tested this hypothesis by observing the foraging choices of Amblyseius swirskii (Athias-Henriot) mites (Mesostigmata: Phytoseiidae), which were first maintained on either prey (broad mites) or corn pollen, and then offered familiar and unfamiliar foods. A. swirskii exhibited strong fidelity to familiar food, whether prey or pollen, suggesting there are physiological or behavioral costs involved in shifting between such different foods. Results illustrate the importance of previous diet for subsequent pest consumption by omnivorous natural enemies. PMID:27271945

  18. Decisions among the Undecided: Implicit Attitudes Predict Future Voting Behavior of Undecided Voters

    PubMed Central

    Lundberg, Kristjen B.; Payne, B. Keith

    2014-01-01

    Implicit attitudes have been suggested as a key to unlock the hidden preferences of undecided voters. Past research, however, offered mixed support for this hypothesis. The present research used a large nationally representative sample and a longitudinal design to examine the predictive utility of implicit and explicit attitude measures in the 2008 U.S. presidential election. In our analyses, explicit attitudes toward candidates predicted voting better for decided than undecided voters, but implicit candidate attitudes were predictive of voting for both decided and undecided voters. Extending our examination to implicit and explicit racial attitudes, we found the same pattern. Taken together, these results provide convergent evidence that implicit attitudes predict voting about as well for undecided as for decided voters. We also assessed a novel explanation for these effects by evaluating whether implicit attitudes may predict the choices of undecided voters, in part, because they are neglected when people introspect about their confidence. Consistent with this idea, we found that the extremity of explicit but not implicit attitudes was associated with greater confidence. These analyses shed new light on the utility of implicit measures in predicting future behavior among individuals who feel undecided. Considering the prior studies together with this new evidence, the data seem to be consistent that implicit attitudes may be successful in predicting the behavior of undecided voters. PMID:24489666

  19. Prey vulnerability to peacock cichlids and largemouth bass based on predator gape and prey body depth

    USGS Publications Warehouse

    Hill, Jeffrey E.; Nico, Leo G.; Cichra, Charles E.; Gilbert, Carter R.

    2005-01-01

    The interaction of prey fish body depth and predator gape size may produce prey assemblages dominated by invulnerable prey and excessive prey-to-predator biomass ratios. Peacock cichlids (Cichla ocellaris) were stocked into southeast Florida canals to consume excess prey fish biomass, particularly spotted tilapia (Tilapia mariae). The ecomorphologically similar largemouth bass (Micropterus salmoides) was already present in the canals. We present relations of length-specific gape size for peacock cichlids and largemouth bass. Both predators have broadly overlapping gape size, but largemouth bass ?126 mm total length have slightly larger gape sizes than peacock cichlids of the same length. Also, we experimentally tested the predictions of maximum prey size for peacock cichlids and determined that a simple method of measuring gape size used for largemouth bass also is appropriate for peacock cichlids. Lastly, we determined relations of body depth and length of prey species to investigate relative vulnerability. Using a simple predator-prey model and length frequencies of predators and bluegill (Lepomis macrochirus), redear sunfish (Lepomis microlophus), and spotted tilapia prey, we documented that much of the prey biomass in southeast Florida canals is unavailable for largemouth bass and peacock cichlid predation.

  20. Disentangling taste and toxicity in aposematic prey.

    PubMed

    Holen, Øistein Haugsten

    2013-02-22

    Many predators quickly learn to avoid attacking aposematic prey. If the prey vary in toxicity, the predators may alternatively learn to capture and taste-sample prey carefully before ingesting or rejecting them (go-slow behaviour). An increase in prey toxicity is generally thought to decrease predation on prey populations. However, while prey with a higher toxin load are more harmful to ingest, they may also be easier to recognize and reject owing to greater distastefulness, which can facilitate a taste-sampling foraging strategy. Here, the classic diet model is used to study the separate effects of taste and toxicity on predator preferences. The taste-sampling process is modelled using signal detection theory. The model is applicable to automimicry and batesian mimicry. It shows that when the defensive toxin is sufficiently distasteful, a mimicry complex may be less profitable to the predator and better protected against predation if the models are moderately toxic than if they are highly toxic. Moreover, taste mimicry can reduce the profitability of the mimicry complex and increase protection against predation. The results are discussed in relation to the selection pressures acting on prey defences and the evolution of mimicry. PMID:23256198

  1. Fluorescent prey traps in carnivorous plants.

    PubMed

    Kurup, R; Johnson, A J; Sankar, S; Hussain, A A; Sathish Kumar, C; Sabulal, B

    2013-05-01

    Carnivorous plants acquire most of their nutrients by capturing ants, insects and other arthropods through their leaf-evolved biological traps. So far, the best-known attractants in carnivorous prey traps are nectar, colour and olfactory cues. Here, fresh prey traps of 14 Nepenthes, five Sarracenia, five Drosera, two Pinguicula species/hybrids, Dionaea muscipula and Utricularia stellaris were scanned at UV 366 nm. Fluorescence emissions of major isolates of fresh Nepenthes khasiana pitcher peristomes were recorded at an excitation wavelength of 366 nm. N. khasiana field pitcher peristomes were masked by its slippery zone extract, and prey capture rates were compared with control pitchers. We found the existence of distinct blue fluorescence emissions at the capture spots of Nepenthes, Sarracenia and Dionaea prey traps at UV 366 nm. These alluring blue emissions gradually developed with the growth of the prey traps and diminished towards their death. On excitation at 366 nm, N. khasiana peristome 3:1 CHCl3–MeOH extract and its two major blue bands showed strong fluorescence emissions at 430–480 nm. Masking of blue emissions on peristomes drastically reduced prey capture in N. khasiana pitchers. We propose these molecular emissions as a critical factor attracting arthropods and other visitors to these carnivorous traps. Drosera, Pinguicula and Utricularia prey traps showed only red chlorophyll emissions at 366 nm. PMID:23696970

  2. Group formation stabilizes predator-prey dynamics.

    PubMed

    Fryxell, John M; Mosser, Anna; Sinclair, Anthony R E; Packer, Craig

    2007-10-25

    Theoretical ecology is largely founded on the principle of mass action, in which uncoordinated populations of predators and prey move in a random and well-mixed fashion across a featureless landscape. The conceptual core of this body of theory is the functional response, predicting the rate of prey consumption by individual predators as a function of predator and/or prey densities. This assumption is seriously violated in many ecosystems in which predators and/or prey form social groups. Here we develop a new set of group-dependent functional responses to consider the ecological implications of sociality and apply the model to the Serengeti ecosystem. All of the prey species typically captured by Serengeti lions (Panthera leo) are gregarious, exhibiting nonlinear relationships between prey-group density and population density. The observed patterns of group formation profoundly reduce food intake rates below the levels expected under random mixing, having as strong an impact on intake rates as the seasonal migratory behaviour of the herbivores. A dynamical system model parameterized for the Serengeti ecosystem (using wildebeest (Connochaetes taurinus) as a well-studied example) shows that grouping strongly stabilizes interactions between lions and wildebeest. Our results suggest that social groups rather than individuals are the basic building blocks around which predator-prey interactions should be modelled and that group formation may provide the underlying stability of many ecosystems. PMID:17960242

  3. Ecoepidemics with Two Strains: Diseased Prey.

    NASA Astrophysics Data System (ADS)

    Elena, Elisa; Grammauro, Maria; Venturino, Ezio

    2011-09-01

    In this work we present a minimal model for an ecoepidemic situation with two diseases affecting the prey population. The main assumptions are the following ones. The predators recognize and hunt only the healthy prey. An infected prey of one strain becomes immune to the other one. The major finding shows that the two strains cannot simultaneously thrive in the system, contrary to the standard assumptions in epidemiology. But this rather unexpected and remarkable result, paralleling another one when the epidemics affects the predators, is most likely due to the assumptions made.

  4. Feeling the heat: the effect of acute temperature changes on predator–prey interactions in coral reef fish

    PubMed Central

    Allan, Bridie J. M.; Domenici, Paolo; Munday, Phillip L.; McCormick, Mark I.

    2015-01-01

    Recent studies demonstrate that the elevated temperatures predicted to occur by the end of the century can affect the physiological performance and behaviour of larval and juvenile fishes; however, little is known of the effect of these temperatures on ecological processes, such as predator–prey interactions. Here, we show that exposure to elevated temperatures significantly affected the predator–prey interactions of a pair of common reef fish, the planktivorous damselfish (Pomacentrus wardi) and the piscivorous dottyback (Pseudochromis fuscus). When predators exposed to elevated temperatures interacted with prey exposed in a similar manner, maximal attack speeds increased. This effect coupled with decreasing prey escape speeds and escape distances led to increased predation rates. Prey exposed to elevated temperatures also had decreased reaction distances and increased apparent looming threshold, suggesting that their sensory performance was affected. This occurred despite the increase in maximal attack speeds, which in other species has been shown to increase reaction distances. These results suggest that the escape performance of prey is sensitive to short-term increases in ambient temperature. As marine environments become more thermally variable in the future, our results demonstrate that some predators may become more successful, suggesting that there will be strong selection for the maintenance of maximal escape performance in prey. In the present era of rapid climate change, understanding how changes to individual performance influence the relationships between predators and their prey will be increasingly important in predicting the effects of climate change within ecosystems. PMID:27293696

  5. Highly Stable Evolution of Earth's Future Orbit despite Chaotic Behavior of the Solar System

    NASA Astrophysics Data System (ADS)

    Zeebe, Richard E.

    2015-09-01

    Due to the chaotic nature of the solar system, the question of its dynamic long-term stability can only be answered in a statistical sense, for instance, based on numerical ensemble integrations of nearby orbits. Destabilization of the inner planets, including catastrophic encounters and/or collisions involving the Earth, has been suggested to be initiated through a large increase in Mercury’s eccentricity ({e}{M}), with an estimated probability of ˜1%. However, it has recently been shown that the statistics of numerical solar system integrations are sensitive to the accuracy and type of numerical algorithm. Here, I report results from computationally demanding ensemble integrations (N = 1600 with slightly different initial conditions) at unprecedented accuracy based on the full equations of motion of the eight planets and Pluto over 5 Gyr, including contributions from general relativity. The standard symplectic algorithm used for long-term integrations produced spurious results for highly eccentric orbits and during close encounters, which were hence integrated with a suitable Bulirsch-Stoer algorithm, specifically designed for these situations. The present study yields odds for a large increase in Mercury’s eccentricity that are less than previous estimates. Strikingly, in two solutions, Mercury continued on highly eccentric orbits (after reaching {e}{M} values >0.93) for 80-100 Myr before colliding with Venus or the Sun. Most importantly, none of the 1600 solutions led to a close encounter involving the Earth or a destabilization of Earth’s orbit in the future. I conclude that Earth’s orbit will be dynamically highly stable for billions of years in the future, despite the chaotic behavior of the solar system.

  6. Unsuccessful attacks dominate a drone-preying wasp's hunting performance near stingless bee nests.

    PubMed

    Koedam, D; Slaa, E J; Biesmeijer, J C; Nogueira-Neto, P

    2009-01-01

    Bee males (drones) of stingless bees tend to congregate near entrances of conspecific nests, where they wait for virgin queens that initiate their nuptial flight. We observed that the Neotropical solitary wasp Trachypus boharti (Hymenoptera, Cabronidae) specifically preys on males of the stingless bee Scaptotrigona postica (Hymenoptera, Apidae); these wasps captured up to 50 males per day near the entrance of a single hive. Over 90% of the wasp attacks were unsuccessful; such erroneous attacks often involved conspecific wasps and worker bees. After the capture of non-male prey, wasps almost immediately released these individuals unharmed and continued hunting. A simple behavioral experiment showed that at short distances wasps were not specifically attracted to S. postica males nor were they repelled by workers of the same species. Likely, short-range prey detection near the bees' nest is achieved mainly by vision whereas close-range prey recognition is based principally on chemical and/or mechanical cues. We argue that the dependence on the wasp's visual perception during attack and the crowded and dynamic hunting conditions caused wasps to make many preying attempts that failed. Two wasp-density-related factors, wasp-prey distance and wasp-wasp encounters, may account for the fact that the highest male capture and unsuccessful wasp bee encounter rates occurred at intermediate wasp numbers. PMID:19554768

  7. Beaked whales echolocate on prey.

    PubMed Central

    Johnson, Mark; Madsen, Peter T; Zimmer, Walter M X; de Soto, Natacha Aguilar; Tyack, Peter L

    2004-01-01

    Beaked whales (Cetacea: Ziphiidea) of the genera Ziphius and Mesoplodon are so difficult to study that they are mostly known from strandings. How these elusive toothed whales use and react to sound is of concern because they mass strand during naval sonar exercises. A new non-invasive acoustic ording tag was attached to four beaked whales(two Mesoplodon densirostris and two Ziphius cavirostris) and recorded high-frequency clicks during deep dives. The tagged whales only clicked at depths below 200 m, down to a maximum depth of 1267 m. Both species produced a large number of short, directional, ultrasonic clicks with significant energy below 20 kHz. The tags recorded echoes from prey items; to our knowledge, a first for any animal echolocating in the wild. As far as we are aware, these echoes provide the first direct evidence on how free-ranging toothed whales use echolocation in foraging. The strength of these echoes suggests that the source level of Mesoplodon clicks is in the range of 200-220 dB re 1 microPa at 1 m.This paper presents conclusive data on the normal vocalizations of these beaked whale species, which may enable acoustic monitoring to mitigate exposure to sounds intense enough to harm them. PMID:15801582

  8. Beaked whales echolocate on prey.

    PubMed

    Johnson, Mark; Madsen, Peter T; Zimmer, Walter M X; de Soto, Natacha Aguilar; Tyack, Peter L

    2004-12-01

    Beaked whales (Cetacea: Ziphiidea) of the genera Ziphius and Mesoplodon are so difficult to study that they are mostly known from strandings. How these elusive toothed whales use and react to sound is of concern because they mass strand during naval sonar exercises. A new non-invasive acoustic ording tag was attached to four beaked whales(two Mesoplodon densirostris and two Ziphius cavirostris) and recorded high-frequency clicks during deep dives. The tagged whales only clicked at depths below 200 m, down to a maximum depth of 1267 m. Both species produced a large number of short, directional, ultrasonic clicks with significant energy below 20 kHz. The tags recorded echoes from prey items; to our knowledge, a first for any animal echolocating in the wild. As far as we are aware, these echoes provide the first direct evidence on how free-ranging toothed whales use echolocation in foraging. The strength of these echoes suggests that the source level of Mesoplodon clicks is in the range of 200-220 dB re 1 microPa at 1 m. This paper presents conclusive data on the normal vocalizations of these beaked whale species, which may enable acoustic monitoring to mitigate exposure to sounds intense enough to harm them. PMID:15801582

  9. Are lemmings prey or predators?

    NASA Astrophysics Data System (ADS)

    Turchin, P.; Oksanen, L.; Ekerholm, P.; Oksanen, T.; Henttonen, H.

    2000-06-01

    Large oscillations in the populations of Norwegian lemmings have mystified both professional ecologists and lay public. Ecologists suspect that these oscillations are driven by a trophic mechanism: either an interaction between lemmings and their food supply, or an interaction between lemmings and their predators. If lemming cycles are indeed driven by a trophic interaction, can we tell whether lemmings act as the resource (`prey') or the consumer (`predator')? In trophic interaction models, peaks of resource density generally have a blunt, rounded shape, whereas peaks of consumer density are sharp and angular. Here we have applied several statistical tests to three lemming datasets and contrasted them with comparable data for cyclic voles. We find that vole peaks are blunt, consistent with their cycles being driven by the interaction with predators. In contrast, the shape of lemming peaks is consistent with the hypothesis that lemmings are functional predators, that is, their cycles are driven by their interaction with food plants. Our findings suggest that a single mechanism, such as interaction between rodents and predators, is unlikely to provide the `universal' explanation of all cyclic rodent dynamics.

  10. Influence of predator mutual interference and prey refuge on Lotka-Volterra predator-prey dynamics

    NASA Astrophysics Data System (ADS)

    Chen, Liujuan; Chen, Fengde; Wang, Yiqin

    2013-11-01

    A Lotka-Volterra predator-prey model incorporating a constant number of prey using refuges and mutual interference for predator species is presented. By applying the divergency criterion and theories on exceptional directions and normal sectors, we show that the interior equilibrium is always globally asymptotically stable and two boundary equilibria are both saddle points. Our results indicate that prey refuge has no influence on the coexistence of predator and prey species of the considered model under the effects of mutual interference for predator species, which differently from the conclusion without predator mutual interference, thus improving some known ones. Numerical simulations are performed to illustrate the validity of our results.

  11. Visual illusions in predator-prey interactions: birds find moving patterned prey harder to catch.

    PubMed

    Hämäläinen, Liisa; Valkonen, Janne; Mappes, Johanna; Rojas, Bibiana

    2015-09-01

    Several antipredator strategies are related to prey colouration. Some colour patterns can create visual illusions during movement (such as motion dazzle), making it difficult for a predator to capture moving prey successfully. Experimental evidence about motion dazzle, however, is still very scarce and comes only from studies using human predators capturing moving prey items in computer games. We tested a motion dazzle effect using for the first time natural predators (wild great tits, Parus major). We used artificial prey items bearing three different colour patterns: uniform brown (control), black with elongated yellow pattern and black with interrupted yellow pattern. The last two resembled colour patterns of the aposematic, polymorphic dart-poison frog Dendrobates tinctorius. We specifically tested whether an elongated colour pattern could create visual illusions when combined with straight movement. Our results, however, do not support this hypothesis. We found no differences in the number of successful attacks towards prey items with different patterns (elongated/interrupted) moving linearly. Nevertheless, both prey types were significantly more difficult to catch compared to the uniform brown prey, indicating that both colour patterns could provide some benefit for a moving individual. Surprisingly, no effect of background (complex vs. plain) was found. This is the first experiment with moving prey showing that some colour patterns can affect avian predators' ability to capture moving prey, but the mechanisms lowering the capture rate are still poorly understood. PMID:25947086

  12. Chemical Basis of Prey Recognition in Thamnophiine Snakes: The Unexpected New Roles of Parvalbumins

    PubMed Central

    Smargiassi, Maïté; Daghfous, Gheylen; Leroy, Baptiste; Legreneur, Pierre; Toubeau, Gerard; Bels, Vincent; Wattiez, Ruddy

    2012-01-01

    Detecting and locating prey are key to predatory success within trophic chains. Predators use various signals through specialized visual, olfactory, auditory or tactile sensory systems to pinpoint their prey. Snakes chemically sense their prey through a highly developed auxiliary olfactory sense organ, the vomeronasal organ (VNO). In natricine snakes that are able to feed on land and water, the VNO plays a critical role in predatory behavior by detecting cues, known as vomodors, which are produced by their potential prey. However, the chemical nature of these cues remains unclear. Recently, we demonstrated that specific proteins–parvalbumins–present in the cutaneous mucus of the common frog (Rana temporaria) may be natural chemoattractive proteins for these snakes. Here, we show that parvalbumins and parvalbumin-like proteins, which are mainly intracellular, are physiologically present in the epidermal mucous cells and mucus of several frog and fish genera from both fresh and salt water. These proteins are located in many tissues and function as Ca2+ buffers. In addition, we clarified the intrinsic role of parvalbumins present in the cutaneous mucus of amphibians and fishes. We demonstrate that these Ca2+-binding proteins participate in innate bacterial defense mechanisms by means of calcium chelation. We show that these parvalbumins are chemoattractive for three different thamnophiine snakes, suggesting that these chemicals play a key role in their prey-recognition mechanism. Therefore, we suggest that recognition of parvalbumin-like proteins or other calcium-binding proteins by the VNO could be a generalized prey-recognition process in snakes. Detecting innate prey defense mechanism compounds may have driven the evolution of this predator-prey interaction. PMID:22761824

  13. Time orientation and eating behavior: Unhealthy eaters consider immediate consequences, while healthy eaters focus on future health.

    PubMed

    Dassen, Fania C M; Houben, Katrijn; Jansen, Anita

    2015-08-01

    Time orientation could play an important role in eating behavior. The current study investigated whether eating behavior is associated with the Consideration of Future Consequences scale (CFC). Specifically, it was examined whether unhealthy eaters consider the future less and are more concerned with immediate gratification. A related measure of time orientation is delay discounting, a process by which a reinforcer becomes less valuable when considered later in time. Recent research argues that the relation between time orientation and health behaviors is measured best at a behavior-specific level. In the current study, we explored the relationships between CFC and discount rate - both general and food-specific - and their influence on healthy eating. Participants with ages 18 to 60 (N = 152; final sample N = 146) filled in an online questionnaire consisting of the CFC, a food-specific version of the CFC (CFC-food), the Monetary Choice Questionnaire (MCQ) and an adapted MCQ version with snack food as a reinforcer. Self-reported healthy eating was positively related to the future subscale (r = .48, p < .001) and negatively to the immediate subscale of the CFC-food (r = -.43, p < .001). The general CFC and discount rate (MCQ and MCQ-snack) were not related to healthy eating (all p > .05). In order to predict behavior, measurements of time orientation should thus be tailored to the behavior of interest. Based on current results, shifting one's concern from the immediate consequences of eating to a more future-oriented perspective may present an interesting target for future interventions aimed at promoting healthy eating and reducing overweight. PMID:25814191

  14. Insect prey characteristics affecting regional variation in chimpanzee tool use.

    PubMed

    Sanz, Crickette M; Deblauwe, Isra; Tagg, Nikki; Morgan, David B

    2014-06-01

    It is an ongoing interdisciplinary pursuit to identify the factors shaping the emergence and maintenance of tool technology. Field studies of several primate taxa have shown that tool using behaviors vary within and between populations. While similarity in tools over spatial and temporal scales may be the product of socially learned skills, it may also reflect adoption of convergent strategies that are tailored to specific prey features. Much has been claimed about regional variation in chimpanzee tool use, with little attention to the ecological circumstances that may have shaped such differences. This study examines chimpanzee tool use in termite gathering to evaluate the extent to which the behavior of insect prey may dictate chimpanzee technology. More specifically, we conducted a systematic comparison of chimpanzee tool use and termite prey between the Goualougo Triangle in the Republic of Congo and the La Belgique research site in southeast Cameroon. Apes at both of these sites are known to use tool sets to gather several species of termites. We collected insect specimens and measured the characteristics of their nests. Associated chimpanzee tool assemblages were documented at both sites and video recordings were conducted in the Goualougo Triangle. Although Macrotermitinae assemblages were identical, we found differences in the tools used to gather these termites. Based on measurements of the chimpanzee tools and termite nests at each site, we concluded that some characteristics of chimpanzee tools were directly related to termite nest structure. While there is a certain degree of uniformity within approaches to particular tool tasks across the species range, some aspects of regional variation in hominoid technology are likely adaptations to subtle environmental differences between populations or groups. Such microecological differences between sites do not negate the possibility of cultural transmission, as social learning may be required to transmit

  15. Contingency Analysis of Caregiver Behavior: Implications for Parent Training and Future Directions

    ERIC Educational Resources Information Center

    Stocco, Corey S.; Thompson, Rachel H.

    2015-01-01

    Parent training is often a required component of effective treatment for a variety of common childhood problems. Although behavior analysts have developed several effective parent-training technologies, we know little about the contingencies that affect parent behavior. Child behavior is one source of control for parent behavior that likely…

  16. Cognitive-Behavioral Therapy for PTSD and Depression Symptoms Reduces Risk for Future Intimate Partner Violence among Interpersonal Trauma Survivors

    ERIC Educational Resources Information Center

    Iverson, Katherine M.; Gradus, Jaimie L.; Resick, Patricia A.; Suvak, Michael K.; Smith, Kamala F.; Monson, Candice M.

    2011-01-01

    Objective: Women who develop symptoms of posttraumatic stress disorder (PTSD) and depression subsequent to interpersonal trauma are at heightened risk for future intimate partner violence (IPV) victimization. Cognitive-behavioral therapy (CBT) is effective in reducing PTSD and depression symptoms, yet limited research has investigated the…

  17. Simulation and analysis of a model dinoflagellate predator-prey system

    NASA Astrophysics Data System (ADS)

    Mazzoleni, M. J.; Antonelli, T.; Coyne, K. J.; Rossi, L. F.

    2015-12-01

    This paper analyzes the dynamics of a model dinoflagellate predator-prey system and uses simulations to validate theoretical and experimental studies. A simple model for predator-prey interactions is derived by drawing upon analogies from chemical kinetics. This model is then modified to account for inefficiencies in predation. Simulation results are shown to closely match the model predictions. Additional simulations are then run which are based on experimental observations of predatory dinoflagellate behavior, and this study specifically investigates how the predatory dinoflagellate Karlodinium veneficum uses toxins to immobilize its prey and increase its feeding rate. These simulations account for complex dynamics that were not included in the basic models, and the results from these computational simulations closely match the experimentally observed predatory behavior of K. veneficum and reinforce the notion that predatory dinoflagellates utilize toxins to increase their feeding rate.

  18. On some free boundary problems of the prey-predator model

    NASA Astrophysics Data System (ADS)

    Wang, Mingxin

    In this paper we investigate some free boundary problems for the Lotka-Volterra type prey-predator model in one space dimension. The main objective is to understand the asymptotic behavior of the two species (prey and predator) spreading via a free boundary. We prove a spreading-vanishing dichotomy, namely the two species either successfully spread to the entire space as time t goes to infinity and survive in the new environment, or they fail to establish and die out in the long run. The long time behavior of solution and criteria for spreading and vanishing are also obtained. Finally, when spreading successfully, we provide an estimate to show that the spreading speed (if exists) cannot be faster than the minimal speed of traveling wavefront solutions for the prey-predator model on the whole real line without a free boundary.

  19. Porpoises: From predators to prey

    NASA Astrophysics Data System (ADS)

    Leopold, Mardik F.; Begeman, Lineke; Heße, Eileen; van der Hiele, Jaap; Hiemstra, Sjoukje; Keijl, Guido; Meesters, Erik H.; Mielke, Lara; Verheyen, Dorien; Gröne, Andrea

    2015-03-01

    Along the Dutch shores hundreds of harbour porpoises Phocoena phocoena are stranded each year. A recurrent phenomenon in the Netherlands is a surge of strandings in late winter and early spring of severely mutilated porpoises, that are mostly in good nutritional body condition (thick blubber layer). These mutilated porpoises have parts of the skin and blubber, and sometimes of the muscle tissue missing. By reviewing photographs of stranded animals taken at the stranding sites as well as autopsy results we found 273 mutilated animals from 2005 to 2012. Mutilations could be classified into several categories, but wounds had been mostly inflicted to the sides of these animals, in a zigzag fashion, or to the throat/cheek region. The stomach contents of 31 zigzags, 12 throats/cheeks and 31 control animals that were not mutilated, from the same age and blubber thickness categories were compared; all these animals had stranded between December and April, 2006-2012. The diet of individuals with zigzag lesions to their sides consisted for a large part of gobies, while animals that had wounds at the throat/cheek had been feeding predominately on clupeids. In comparison, animals without mutilations had a more varied diet, including gobies and clupeids, but also a large proportion of sandeels and gadoids. The finding that the type of mutilation corresponds to a certain diet suggests that porpoises that were feeding on different prey, or in different micro-habitats, were hit in different ways. Animals feeding at the sea floor (on gobies) apparently run a risk of being hit from the side, while animals supposedly feeding higher in the water column (on schooling clupeids), were predominantly hit from below, in the throat region. The wider variation in the diets of non-mutilated porpoises is suggestive of them using a larger variety of micro-habitats.

  20. Significance of Selective Predation and Development of Prey Protection Measures for Juvenile Salmonids in the Columbia and Snake River Reservoirs: Annual Progress Report, February 1993-February 1994.

    SciTech Connect

    Poe, Thomas P.

    1994-08-01

    This report addresses the problem of predator-prey interactions of juvenile salmonids in the Columbia and Snake River. Six papers are included on selective predation and prey protection. Attention is focused on monitoring the movements, the distribution, and the behavior of juvenile chinook salmon and northern squawfish.

  1. Human Behavioral Pharmacology, Past, Present, and Future: Symposium Presented at the 50th Annual Meeting of the Behavioral Pharmacology Society

    PubMed Central

    Comer, Sandra D.; Bickel, Warren K.; Yi, Richard; de Wit, Harriet; Higgins, Stephen T.; Wenger, Galen R.; Johanson, Chris-Ellyn; Kreek, Mary Jeanne

    2010-01-01

    A symposium held at the 50th annual meeting of the Behavioral Pharmacology Society in May 2007 reviewed progress in the human behavioral pharmacology of drug abuse. Studies on drug self-administration in humans are reviewed that assessed reinforcing and subjective effects of drugs of abuse. The close parallels observed between studies in humans and laboratory animals using similar behavioral techniques have broadened our understanding of the complex nature of the pharmacological and behavioral factors controlling drug self-administration. The symposium also addressed the role that individual differences, such as gender, personality, and genotype play in determining the extent of self-administration of illicit drugs in human populations. Knowledge of how these factors influence human drug self-administration has helped validate similar differences observed in laboratory animals. In recognition that drug self-administration is but one of many choices available in the lives of humans, the symposium addressed the ways in which choice behavior can be studied in humans. These choice studies in human drug abusers have opened up new and exciting avenues of research in laboratory animals. Finally, the symposium reviewed behavioral pharmacology studies conducted in drug abuse treatment settings and the therapeutic benefits that have emerged from these studies. PMID:20664330

  2. DNA barcoding reveals novel insights into pterygophagy and prey selection in distichodontid fishes (Characiformes: Distichodontidae)

    PubMed Central

    Arroyave, Jairo; Stiassny, Melanie L J

    2014-01-01

    DNA barcoding was used to investigate dietary habits and prey selection in members of the African-endemic family Distichodontidae noteworthy for displaying highly specialized ectoparasitic fin-eating behaviors (pterygophagy). Fin fragments recovered from the stomachs of representatives of three putatively pterygophagous distichodontid genera (Phago, Eugnathichthys, and Ichthyborus) were sequenced for the mitochondrial gene co1. DNA barcodes (co1 sequences) were then used to identify prey items in order to determine whether pterygophagous distichodontids are opportunistic generalists or strict specialists with regard to prey selection and, whether as previously proposed, aggressive mimicry is used as a strategy for successful pterygophagy. Our findings do not support the hypothesis of aggressive mimicry suggesting instead that, despite the possession of highly specialized trophic anatomies, fin-eating distichodontids are opportunistic generalists, preying on fishes from a wide phylogenetic spectrum and to the extent of engaging in cannibalism. This study demonstrates how DNA barcoding can be used to shed light on evolutionary and ecological aspects of highly specialized ectoparasitic fin-eating behaviors by enabling the identification of prey species from small pieces of fins found in fish stomachs. PMID:25512849

  3. Development of survival skills in captive-raised Siberian polecats (Mustela eversmanni) I: locating prey

    USGS Publications Warehouse

    Miller, Brian; Biggins, Dean; Wemmer, Chris; Powell, Roger; Hanebury, Lou; Horn, Deborah; Vargas, Astrid

    1990-01-01

    Captive-raised mustelids appear to have a rudimentary capacity to kill prey, but the skills necessary for locating prey may be eroded during captivity. We tested the maturational component of prey-searching behavior with captive-raised Siberian polecats (Mustela eversmanni) by subjecting polecats to a simulated prairie dog colony of 6 burrows within a 200 m2 arena. Ten naive Siberian polecats at ages 2.5, 3.5, and 4.5 months (30 total) were deprived of food for 12 hours. A dead prairie dog was placed in 1 prairie dog burrow and the other 5 were empty. A single Siberian polecat was released onto the colony shortly before sunset and its movements monitored from an observation tower. Older Siberian polecats located prey significantly quicker than younger polecats, but all age groups spent a great deal of time in surface activity not directed toward a burrow. When Siberian polecats were about 10 months old, all burrows in the arena were plugged with dirt including the burrow with the prairie dog. In this winter test, Siberian polecats located the prey but still spent a great deal of time in non-burrow directed surface activity. Economical use of surface time, with a low amount of non-burrow directed behavior, would presumably reduce the risk of predation for hunting polecats.

  4. DNA barcoding reveals novel insights into pterygophagy and prey selection in distichodontid fishes (Characiformes: Distichodontidae).

    PubMed

    Arroyave, Jairo; Stiassny, Melanie L J

    2014-12-01

    DNA barcoding was used to investigate dietary habits and prey selection in members of the African-endemic family Distichodontidae noteworthy for displaying highly specialized ectoparasitic fin-eating behaviors (pterygophagy). Fin fragments recovered from the stomachs of representatives of three putatively pterygophagous distichodontid genera (Phago, Eugnathichthys, and Ichthyborus) were sequenced for the mitochondrial gene co1. DNA barcodes (co1 sequences) were then used to identify prey items in order to determine whether pterygophagous distichodontids are opportunistic generalists or strict specialists with regard to prey selection and, whether as previously proposed, aggressive mimicry is used as a strategy for successful pterygophagy. Our findings do not support the hypothesis of aggressive mimicry suggesting instead that, despite the possession of highly specialized trophic anatomies, fin-eating distichodontids are opportunistic generalists, preying on fishes from a wide phylogenetic spectrum and to the extent of engaging in cannibalism. This study demonstrates how DNA barcoding can be used to shed light on evolutionary and ecological aspects of highly specialized ectoparasitic fin-eating behaviors by enabling the identification of prey species from small pieces of fins found in fish stomachs. PMID:25512849

  5. The Effects of Spatially Heterogeneous Prey Distributions on Detection Patterns in Foraging Seabirds

    PubMed Central

    Miramontes, Octavio; Boyer, Denis; Bartumeus, Frederic

    2012-01-01

    Many attempts to relate animal foraging patterns to landscape heterogeneity are focused on the analysis of foragers movements. Resource detection patterns in space and time are not commonly studied, yet they are tightly coupled to landscape properties and add relevant information on foraging behavior. By exploring simple foraging models in unpredictable environments we show that the distribution of intervals between detected prey (detection statistics) is mostly determined by the spatial structure of the prey field and essentially distinct from predator displacement statistics. Detections are expected to be Poissonian in uniform random environments for markedly different foraging movements (e.g. Lévy and ballistic). This prediction is supported by data on the time intervals between diving events on short-range foraging seabirds such as the thick-billed murre (Uria lomvia). However, Poissonian detection statistics is not observed in long-range seabirds such as the wandering albatross (Diomedea exulans) due to the fractal nature of the prey field, covering a wide range of spatial scales. For this scenario, models of fractal prey fields induce non-Poissonian patterns of detection in good agreement with two albatross data sets. We find that the specific shape of the distribution of time intervals between prey detection is mainly driven by meso and submeso-scale landscape structures and depends little on the forager strategy or behavioral responses. PMID:22514629

  6. Restructuring fundamental predator-prey models by recognising prey-dependent conversion efficiency and mortality rates.

    PubMed

    Li, Jiqiu; Montagnes, David J S

    2015-05-01

    Incorporating protozoa into population models (from simple predator-prey explorations to complex food web simulations) is of conceptual, ecological, and economic importance. From theoretical and empirical perspectives, we expose unappreciated complexity in the traditional predator-prey model structure and provide a parsimonious solution, especially for protistologists. We focus on how prey abundance alters two key components of models: predator conversion efficiency (e, the proportion of prey converted to predator, before mortality loss) and predator mortality (δ, the portion of the population lost though death). Using a well-established model system (Paramecium and Didinium), we collect data to parameterize a range of existing and novel population models that differ in the functional forms of e and δ. We then compare model simulations to an empirically obtained time-series of predator-prey population dynamics. The analysis indicates that prey-dependent e and δ should be considered when structuring population models and that both prey and predator biomass also vary with prey abundance. Both of these impact the ability of the model to predict population dynamics and, therefore, should be included in theoretical model evaluations and assessment of ecosystem dynamics associated with biomass flux. PMID:25819465

  7. How the Magnitude of Prey Genetic Variation Alters Predator-Prey Eco-Evolutionary Dynamics.

    PubMed

    Cortez, Michael H

    2016-09-01

    Evolution can alter the stability and dynamics of ecological communities; for example, prey evolution can drive cyclic dynamics in predator-prey systems that are not possible in the absence of evolution. However, it is unclear how the magnitude of additive genetic variation in the evolving species mediates those effects. In this study, I explore how the magnitude of prey additive genetic variation determines what effects prey evolution has on the dynamics and stability of predator-prey systems. I use linear stability analysis to decompose the stability of a general eco-evolutionary predator-prey model into components representing the stabilities of the ecological and evolutionary subsystems as well as the interactions between those subsystems. My results show that with low genetic variation, the cyclic dynamics and stability of the system are determined by the ecological subsystem. With increased genetic variation, disruptive selection always destabilizes stable communities, stabilizing selection can stabilize or destabilize communities, and prey evolution can alter predator-prey phase lags. Stability changes occur approximately when the magnitude of genetic variation balances the (in)stabilities of the ecological and evolutionary subsystems. I discuss the connections between my stability results and prior results from the theory of adaptive dynamics. PMID:27501090

  8. Echolocating Bats Cry Out Loud to Detect Their Prey

    PubMed Central

    Surlykke, Annemarie; Kalko, Elisabeth K. V.

    2008-01-01

    Echolocating bats have successfully exploited a broad range of habitats and prey. Much research has demonstrated how time-frequency structure of echolocation calls of different species is adapted to acoustic constraints of habitats and foraging behaviors. However, the intensity of bat calls has been largely neglected although intensity is a key factor determining echolocation range and interactions with other bats and prey. Differences in detection range, in turn, are thought to constitute a mechanism promoting resource partitioning among bats, which might be particularly important for the species-rich bat assemblages in the tropics. Here we present data on emitted intensities for 11 species from 5 families of insectivorous bats from Panamá hunting in open or background cluttered space or over water. We recorded all bats in their natural habitat in the field using a multi-microphone array coupled with photographic methods to assess the bats' position in space to estimate emitted call intensities. All species emitted intense search signals. Output intensity was reduced when closing in on background by 4–7 dB per halving of distance. Source levels of open space and edge space foragers (Emballonuridae, Mormoopidae, Molossidae, and Vespertilionidae) ranged between 122–134 dB SPL. The two Noctilionidae species hunting over water emitted the loudest signals recorded so far for any bat with average source levels of ca. 137 dB SPL and maximum levels above 140 dB SPL. In spite of this ten-fold variation in emitted intensity, estimates indicated, surprisingly, that detection distances for prey varied far less; bats emitting the highest intensities also emitted the highest frequencies, which are severely attenuated in air. Thus, our results suggest that bats within a local assemblage compensate for frequency dependent attenuation by adjusting the emitted intensity to achieve comparable detection distances for prey across species. We conclude that for bats with similar

  9. Future directions in research on sexual minority adolescent mental, behavioral, and sexual health

    PubMed Central

    Mustanski, Brian

    2015-01-01

    This article describes current knowledge on sexual, mental, and behavioral health of sexual minority (SM) youth and identifies gaps that would benefit from future research. A translational sciences framework is used to conceptualize the article, discussing findings and gaps along the spectrum from basic research on prevalence and mechanisms, to intervention development and testing, to implementation. Relative to adults, there has been much less research on adolescents and very few studies that had longitudinal follow-up beyond one year. Due to historical changes in the social acceptance of the SM community, new cohorts are needed to represent contemporary life experiences and associated health consequences. Important theoretical developments have occurred in conceptualizing mechanisms that drive SM health disparities and mechanistic research is underway, including studies that identify individual and structural risk/protective factors. Research opportunities exist in the utilization of sibling-comparison designs, inclusion of parents, and studying romantic relationships. Methodological innovation is needed in sampling SM populations. There has been less intervention research and approaches should consider natural resiliencies, life-course frameworks, prevention science, multiple levels of influence, and the importance of implementation. Regulatory obstacles are created when ethics boards elect to require parental permission and ethics research is needed. There has been inconsistent inclusion of SM populations in the definition of “health disparity population,” which impacts funding and training opportunities. There are incredible opportunities for scholars to make substantial and foundational contributions to help address the health of SM youth, and new funding opportunities to do so. PMID:25575125

  10. Hydrodynamics of jumping for prey capture in Archer fish

    NASA Astrophysics Data System (ADS)

    Techet, A. H.; Shih, A. M.

    2010-11-01

    The prey capture behavior by jumping Archer fish (Toxotes microlepisis) was investigated using high speed imaging and particle imaging velocimetry (PIV). Archer fish are renowned for their ability to spit jets of water at insects and also to jump out of the water to capture their prey. Our investigations reveal that the fish typically fail to reach their prey by jumping when the bait is placed at a height above 3.5 body lengths. After jumping and failing, the fish do not typically jump again, only spit. For our experiments bait was placed between 0.5 and 3.5 body lengths (BL) above the free surface, within reach of jumping, and thus the fish rarely spit unless they missed first by jumping. It is observed that the fish typically position their bodies under the bait with a slight angle, hover momentarily, snap in their pectoral fins, and then flap their tail in an "S-start"-type maneuver with a fixed number of cycles, which increases as a function of bait height. High speed imaging, including time-resolved PIV, was used to capture the kinematics of the jumping behavior and compare the fluid impulse generated during the fast start, jump maneuver with the total change in momentum of the fish body. Maximum acceleration was observed in the early stages of the jump maneuver and was often on the order of 5 to 15 times gravity. Correlations between the maximum energy, power in, number of tail beats, jump height and overall jumping kinematics will be discussed.

  11. Designing serious video games for health behavior change: Current status and future directions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Serious video games for health are designed to entertain while changing a specific health behavior. This article identifies behavioral principles that can guide the development of serious video games focused on changing a variety of health behaviors, including those attempting to decrease risk of o...

  12. Selective Predation of a Stalking Predator on Ungulate Prey

    PubMed Central

    Heurich, Marco; Zeis, Klara; Küchenhoff, Helmut; Müller, Jörg; Belotti, Elisa; Bufka, Luděk; Woelfing, Benno

    2016-01-01

    Prey selection is a key factor shaping animal populations and evolutionary dynamics. An optimal forager should target prey that offers the highest benefits in terms of energy content at the lowest costs. Predators are therefore expected to select for prey of optimal size. Stalking predators do not pursue their prey long, which may lead to a more random choice of prey individuals. Due to difficulties in assessing the composition of available prey populations, data on prey selection of stalking carnivores are still scarce. We show how the stalking predator Eurasian lynx (Lynx lynx) selects prey individuals based on species identity, age, sex and individual behaviour. To address the difficulties in assessing prey population structure, we confirm inferred selection patterns by using two independent data sets: (1) data of 387 documented kills of radio-collared lynx were compared to the prey population structure retrieved from systematic camera trapping using Manly’s standardized selection ratio alpha and (2) data on 120 radio-collared roe deer were analysed using a Cox proportional hazards model. Among the larger red deer prey, lynx selected against adult males—the largest and potentially most dangerous prey individuals. In roe deer lynx preyed selectively on males and did not select for a specific age class. Activity during high risk periods reduced the risk of falling victim to a lynx attack. Our results suggest that the stalking predator lynx actively selects for size, while prey behaviour induces selection by encounter and stalking success rates. PMID:27548478

  13. Selective Predation of a Stalking Predator on Ungulate Prey.

    PubMed

    Heurich, Marco; Zeis, Klara; Küchenhoff, Helmut; Müller, Jörg; Belotti, Elisa; Bufka, Luděk; Woelfing, Benno

    2016-01-01

    Prey selection is a key factor shaping animal populations and evolutionary dynamics. An optimal forager should target prey that offers the highest benefits in terms of energy content at the lowest costs. Predators are therefore expected to select for prey of optimal size. Stalking predators do not pursue their prey long, which may lead to a more random choice of prey individuals. Due to difficulties in assessing the composition of available prey populations, data on prey selection of stalking carnivores are still scarce. We show how the stalking predator Eurasian lynx (Lynx lynx) selects prey individuals based on species identity, age, sex and individual behaviour. To address the difficulties in assessing prey population structure, we confirm inferred selection patterns by using two independent data sets: (1) data of 387 documented kills of radio-collared lynx were compared to the prey population structure retrieved from systematic camera trapping using Manly's standardized selection ratio alpha and (2) data on 120 radio-collared roe deer were analysed using a Cox proportional hazards model. Among the larger red deer prey, lynx selected against adult males-the largest and potentially most dangerous prey individuals. In roe deer lynx preyed selectively on males and did not select for a specific age class. Activity during high risk periods reduced the risk of falling victim to a lynx attack. Our results suggest that the stalking predator lynx actively selects for size, while prey behaviour induces selection by encounter and stalking success rates. PMID:27548478

  14. Experience of Health Complaints and Help Seeking Behavior in Employees Screened for Depressive Complaints and Risk of Future Sickness Absence

    PubMed Central

    Jansen, N. W. H.; Stevens, F. C. J.; van Amelsvoort, L. G. P. M.; Kant, IJ.

    2010-01-01

    Introduction The aim of this study was to examine the associations between on the one hand depressive complaints and risk of future sickness absence and on the other hand experience of health complaints and help seeking behavior in the working population. Methods Cross-sectional data were used from employees working in the banking sector (n = 8,498). The screening instrument included measures to examine the risk of future sickness absence, depressive complaints and help seeking behavior. Results Of employees reporting health complaints, approximately 80% had already sought help for these complaints. Experience of health complaints and subsequent help seeking behavior differed between employees with mild to severe depressive complaints and employees at risk of future sickness absence. Experience of health complaints was highest in employees identified with both concepts (69%) compared with employees identified at risk of future sickness absence only (48%) and with mild to severe depressive complaints only (57%). In those employees identified with one or both concepts and who had not sought help already, intention to seek help was about 50%. Conclusions From a screening perspective, employees who do not experience health complaints or who do not have the intention to seek help may refuse participation in early intervention. This might be a bottleneck in the implementation of preventive interventions in the occupational health setting. PMID:20467796

  15. The smell of success: the amount of prey consumed by predators determines the strength and range of cascading non-consumptive effects

    PubMed Central

    Beauvais, Jeffrey

    2015-01-01

    We examined whether chemically mediated risk perception by prey and the effects of changes in prey behavior on basal resources vary as a function of the amount of prey biomass consumed by the predator. We studied these issues using a tritrophic system composed of blue crabs, Callinectes sapidus (top predator), mud crabs Panopeus herbstii (intermediate prey), and oysters Crassostrea virginica (basal resource). Working in a well characterized field environment where experiments preserve natural patterns of water flow, we found that biomass consumed by a predator determines the range, intensity and nature of prey aversive responses. Predators that consume large amounts of prey flesh more strongly diminish consumption of basal resources by prey and exert effects over a larger range (in space and time) compared to predators that have eaten less. Less well-fed predators produce weaker effects, with the consequence that behaviorally mediated cascades preferentially occur in refuge habitats. Well-fed predators affected prey behavior and increased basal resources up to distances of 1–1.5 m, whereas predators fed restricted diet evoked changes in prey only when they were extremely close, typically 50 cm or less. Thus, consumptive and non-consumptive effects may be coupled; predators that have a greater degree of predatory success will affect prey traits more strongly and non-consumptive and consumptive effects may fluctuate in tandem, with some lag. Moreover, differences among predators in their degree of prey capture will create spatial and temporal variance in risk cue availability in the absence of underlying environmental effects. PMID:26618090

  16. Effects of Deprivation of Vomeronasal Chemoreception on Prey Discrimination in Rattlesnakes

    ERIC Educational Resources Information Center

    Stark, C. Patrick; Tiernan, Chelsea; Chiszar, David

    2011-01-01

    It has been demonstrated that rattlesnakes can discriminate between envenomed and nonenvenomed rodent prey based on venom-related cues deposited during the strike. This behavior is crucial to the snake's ability to choose the chemical trail left by an envenomed rodent fleeing the strike area and aids in the snake's ability to relocate the rodent.…

  17. Positive solutions of a diffusive Leslie-Gower predator-prey model with Bazykin functional response

    NASA Astrophysics Data System (ADS)

    Zhou, Jun

    2014-02-01

    In this paper, we consider a diffusive Leslie-Gower predator-prey model with Bazykin functional response and zero Dirichlet boundary condition. We show the existence, multiplicity and uniqueness of positive solutions when parameters are in different regions. Results are proved by using bifurcation theory, fixed point index theory, energy estimate and asymptotical behavior analysis.

  18. Predator functional response and prey survival: Direct and indirect interactions affecting a marked prey population

    USGS Publications Warehouse

    Miller, David A.; Grand, J.B.; Fondell, T.F.; Anthony, M.

    2006-01-01

    1. Predation plays an integral role in many community interactions, with the number of predators and the rate at which they consume prey (i.e. their functional response) determining interaction strengths. Owing to the difficulty of directly observing predation events, attempts to determine the functional response of predators in natural systems are limited. Determining the forms that predator functional responses take in complex systems is important in advancing understanding of community interactions. 2. Prey survival has a direct relationship to the functional response of their predators. We employed this relationship to estimate the functional response for bald eagle Haliaeetus leucocepalus predation of Canada goose Branta canadensis nests. We compared models that incorporated eagle abundance, nest abundance and alternative prey presence to determine the form of the functional response that best predicted intra-annual variation in survival of goose nests. 3. Eagle abundance, nest abundance and the availability of alternative prey were all related to predation rates of goose nests by eagles. There was a sigmoidal relationship between predation rate and prey abundance and prey switching occurred when alternative prey was present. In addition, predation by individual eagles increased as eagle abundance increased. 4. A complex set of interactions among the three species examined in this study determined survival rates of goose nests. Results show that eagle predation had both prey- and predator-dependent components with no support for ratio dependence. In addition, indirect interactions resulting from the availability of alternative prey had an important role in mediating the rate at which eagles depredated nests. As a result, much of the within-season variation in nest survival was due to changing availability of alternative prey consumed by eagles. 5. Empirical relationships drawn from ecological theory can be directly integrated into the estimation process to

  19. Prey detection with electrical sense in the paddlefish (Polydon spathula)

    NASA Astrophysics Data System (ADS)

    Pei, Xing; Wilkens, Lon; Russell, David; Moss, Frank

    1997-03-01

    Paddlefish,Polyodon spathula, is a threatened species which inhabits major mid-western river systems. Paddlefishes are plankton feeders, preying on small crustaceans including Daphnia sp.. Their rostrum is elongated and flattened into a paddle shape on which many electro-sensitive ampullary receptor cells are located. We demonstrate that the paddlefishes use their electrical sense to locate prey in its food searching behavior. Our experiments show that both Daphnia and the related brine shrimp Artemia produce weak low-frequency electric fields, which are capable of evoking responses in ampullary electroreceptor cells, which were recorded in responses from the primary afferents. The response characteristics of the sensory afferents are low-frequency band pass, which overlap the frequencies of the electric fields produced by the aforementioned plankton. Behavioral experiments also show that the paddlefish detect and strike at dipole -electrodes (0.25uA-1uA) operating at 5 to 10 Hz frequencies. This result supports the hypothesis(Wilkens L, Cox M and Russell D. Amer. Zool. 34, 43 (1994)) that the paddlefish uses its paddle as an antenna to sense the outside world.

  20. Predator-prey interactions, resource depression and patch revisitation

    USGS Publications Warehouse

    Erwin, R.M.

    1989-01-01

    Generalist predators may be confronted by different types of prey in different patches: sedentary and conspicuous, cryptic (with or without refugia), conspicuous and nonsocial, or conspicuous and social. I argue that, where encounter rates with prey are of most importance, patch revisitation should be a profitable tactic where prey have short 'recovery' times (conspicuous, nonsocial prey), or where anti-predator response (e.g. shoaling) may increase conspicuousness. Predictions are made for how temporal changes in prey encounter rates should affect revisit schedules and feeding rates for the 4 different prey types.

  1. INCREASING SAVING BEHAVIOR THROUGH AGE-PROGRESSED RENDERINGS OF THE FUTURE SELF

    PubMed Central

    HERSHFIELD, HAL E.; GOLDSTEIN, DANIEL G.; SHARPE, WILLIAM F.; FOX, JESSE; YEYKELIS, LEO; CARSTENSEN, LAURA L.; BAILENSON, JEREMY N.

    2014-01-01

    Many people fail to save what they need to for retirement (Munnell, Webb, and Golub-Sass 2009). Research on excessive discounting of the future suggests that removing the lure of immediate rewards by pre-committing to decisions, or elaborating the value of future rewards can both make decisions more future-oriented. In this article, we explore a third and complementary route, one that deals not with present and future rewards, but with present and future selves. In line with thinkers who have suggested that people may fail, through a lack of belief or imagination, to identify with their future selves (Parfit 1971; Schelling 1984), we propose that allowing people to interact with age-progressed renderings of themselves will cause them to allocate more resources toward the future. In four studies, participants interacted with realistic computer renderings of their future selves using immersive virtual reality hardware and interactive decision aids. In all cases, those who interacted with virtual future selves exhibited an increased tendency to accept later monetary rewards over immediate ones. PMID:24634544

  2. Behavior analysis and ecological psychology: past, present, and future. a review of Harry Heft's Ecological Psychology in context.

    PubMed

    Morris, Edward K

    2009-09-01

    Relations between behavior analysis and ecological psychology have been strained for years, notwithstanding the occasional comment on their affinities. Harry Heft's (2001)Ecological Psychology in Context provides an occasion for reviewing anew those relations and affinities. It describes the genesis of ecological psychology in James's radical empiricism; addresses Holt's neorealism and Gestalt psychology; and synthesizes Gibson's ecological psychology and Barker's ecobehavioral science as a means for understanding everyday human behavior. Although behavior analysis is excluded from this account, Heft's book warrants a review nonetheless: It describes ecological psychology in ways that are congruent and complementary with behavior analysis (e.g., nonmediational theorizing; the provinces of natural history and natural science). After introducing modern ecological psychology, I comment on (a) Heft's admirable, albeit selective, historiography; (b) his ecological psychology-past and present-as it relates to Skinner's science and system (e.g., affordances, molar behavior); (c) his misunderstandings of Skinner's behaviorism (e.g., reductionistic, mechanistic, molecular); and (d) the theoretical status of Heft's cognitive terms and talk (i.e., in ontology, epistemology, syntax). I conclude by considering the alliance and integration of ecological psychology and behavior analysis, and their implications for unifying and transforming psychology as a life science, albeit more for the future than at present. PMID:20354604

  3. Behavior Analysis and Ecological Psychology: Past, Present, and Future. A Review of Harry Heft's Ecological Psychology in Context

    PubMed Central

    Morris, Edward K

    2009-01-01

    Relations between behavior analysis and ecological psychology have been strained for years, notwithstanding the occasional comment on their affinities. Harry Heft's (2001) Ecological Psychology in Context provides an occasion for reviewing anew those relations and affinities. It describes the genesis of ecological psychology in James's radical empiricism; addresses Holt's neorealism and Gestalt psychology; and synthesizes Gibson's ecological psychology and Barker's ecobehavioral science as a means for understanding everyday human behavior. Although behavior analysis is excluded from this account, Heft's book warrants a review nonetheless: It describes ecological psychology in ways that are congruent and complementary with behavior analysis (e.g., nonmediational theorizing; the provinces of natural history and natural science). After introducing modern ecological psychology, I comment on (a) Heft's admirable, albeit selective, historiography; (b) his ecological psychology—past and present—as it relates to Skinner's science and system (e.g., affordances, molar behavior); (c) his misunderstandings of Skinner's behaviorism (e.g., reductionistic, mechanistic, molecular); and (d) the theoretical status of Heft's cognitive terms and talk (i.e., in ontology, epistemology, syntax). I conclude by considering the alliance and integration of ecological psychology and behavior analysis, and their implications for unifying and transforming psychology as a life science, albeit more for the future than at present. PMID:20354604

  4. Forest structure affects trophic linkages: How silvicultural disturbance impacts bats and their insect prey

    USGS Publications Warehouse

    Dodd, L.E.; Lacki, M.J.; Britzke, E.R.; Buehler, D.A.; Keyser, P.D.; Larkin, J.L.; Rodewald, A.D.; Wigley, T.B.; Wood, P.B.; Rieske, L.K.

    2012-01-01

    Vertebrate insectivores such as bats are a pervasive top-down force on prey populations in forest ecosystems. Conservation focusing on forest-dwelling bats requires understanding of community-level interactions between these predators and their insect prey. Our study assessed bat activity and insect occurrence (abundance and diversity) across a gradient of forest disturbance and structure (silvicultural treatments) in the Central Appalachian region of North America. We conducted acoustic surveys of bat echolocation concurrent with insect surveys using blacklight and malaise traps over 2 years. Predator activity, prey occurrence and prey biomass varied seasonally and across the region. The number of bat echolocation pulses was positively related with forest disturbance, whereas prey demonstrated varied trends. Lepidopteran abundance was negatively related with disturbance, while dipteran abundance and diversity was positively related with disturbance. Coleoptera were unaffected. Neither bat nor insect response variables differed between plot interiors and edges. Correlations between bat activity and vegetative structure reflected differences in foraging behavior among ensembles. Activity of myotine bats was correlated with variables describing sub-canopy vegetation, whereas activity of lasiurine bats was more closely correlated with canopy-level vegetation. Lepidopteran abundance was correlated with variables describing canopy and sub-canopy vegetation, whereas coleopteran and dipteran occurrence were more closely correlated with canopy-level vegetative structure. Our study demonstrates regional variation in bat activity and prey occurrence across a forested disturbance gradient. Land management and conservation efforts should consider the importance of vegetation structure and plant species richness to sustain forest-dwelling bats and their insect prey.

  5. Foraging mechanisms of siscowet lake trout (Salvelinus namaycush siscowet) on pelagic prey

    USGS Publications Warehouse

    Keyler, Trevor D.; Hrabik, Thomas R.; Austin, C. Lee; Gorman, Owen T.; Mensinger, Allen F.

    2015-01-01

    The reaction distance, angle of attack, and foraging success were determined for siscowet lake trout (Salvelinus namaycush siscowet) during laboratory trials under lighting conditions that approximated downwelling spectral irradiance and intensity (9.00 × 108–1.06 × 1014 photons m− 2 s− 1) at daytime depths. Siscowet reaction distance in response to golden shiners (Notemigonus crysoleucas) was directly correlated with increasing light intensity until saturation at 1.86 × 1011 photons m− 2 s− 1, above which reaction distance was constant within the range of tested light intensities. At the lowest tested light intensity, sensory detection was sufficient to locate prey at 25 ± 2 cm, while increasing light intensities increased reaction distance up to 59 ± 2 cm at 1.06 × 1014 photons m− 2 s− 1. Larger prey elicited higher reaction distances than smaller prey at all light intensities while moving prey elicited higher reaction distances than stationary prey at the higher light intensities (6.00 × 109 to 1.06 × 1014 photons m− 2 s− 1). The capture and consumption of prey similarly increased with increasing light intensity while time to capture decreased with increasing light intensity. The majority of orientations toward prey occurred within 120° of the longitudinal axis of the siscowet's eyes, although reaction distances among 30° increments along the entire axis were not significantly different. The developed predictive model will help determine reaction distances for siscowet in various photic environments and will help identify the mechanisms and behavior that allow for low light intensity foraging within freshwater systems.

  6. Estimating prey size and number in crayfish-eating snakes, genus Regina

    USGS Publications Warehouse

    Godley, J.S.; McDiarmid, R.W.; Rojas, N.N.

    1984-01-01

    Snakes of the genus Regina feed almost exclusively on crayfish. The paired, symmetrical gastroliths of crayfish are not digested and are detectable from x-rays of the snake. Gastrolith length is directly proportional to carapace length and can be obtained from x-rays. Carapace length can be converted to kcal of ingested energy. Using these relationships and repeated captures of radio-telemetered Regina, estimates of food consumption and energy intake by freeliving snakes are feasible. New information on prey selectivity, feeding behavior, and predator-prey size relations in Regina grahami and R. septemvittata are presented and compared with similar data for other snakes.

  7. Visual prey detection by near-infrared cues in a fish

    NASA Astrophysics Data System (ADS)

    Meuthen, Denis; Rick, Ingolf P.; Thünken, Timo; Baldauf, Sebastian A.

    2012-12-01

    Many animal species are able to perceive light wavelengths beyond those visible to humans. While numerous species are additionally sensitive to short wavelengths (UV), long wavelengths such as the near-infrared spectrum (NIR) are supposed to be unsuitable for visual perception. Here, we experimentally show that under exclusive NIR illumination, the cichlid fish Pelvicachromis taeniatus displays a clear foraging response towards NIR reflecting prey. Additional control experiments without prey indicate that the observed behavior is not a mere response to the NIR environment. These results give first evidence for NIR visual sensitivity in a functional context and thus challenge the current view about NIR perception.

  8. What do predators really want? The role of gerbil energetic state in determining prey choice by Barn Owls.

    PubMed

    Embar, Keren; Mukherjee, Shomen; Kotler, Burt P

    2014-02-01

    In predator-prey foraging games, predators should respond to variations in prey state. The value of energy for the prey changes depending on season. Prey in a low energetic state and/or in a reproductive state should invest more in foraging and tolerate higher predation risk. This should make the prey more catchable, and thereby, more preferable to predators. We ask, can predators respond to prey state? How does season and state affect the foraging game from the predator's perspective? By letting owls choose between gerbils whose states we experimentally manipulated, we could demonstrate predator sensitivity to prey state and predator selectivity that otherwise may be obscured by the foraging game. During spring, owls invested more time and attacks in the patch with well-fed gerbils. During summer, owls attacked both patches equally, yet allocated more time to the patch with hungry gerbils. Energetic state per se does not seem to be the basis of owl choice. The owls strongly responded to these subtle differences. In summer, gerbils managed their behavior primarily for survival, and the owls equalized capture opportunities by attacking both patches equally. PMID:24669722

  9. Effects of prey quality and predator body size on prey DNA detection success in a centipede predator.

    PubMed

    Eitzinger, B; Unger, E M; Traugott, M; Scheu, S

    2014-08-01

    Predator body size and prey quality are important factors driving prey choice and consumption rates. Both factors might affect prey detection success in PCR-based gut content analysis, potentially resulting in over- or underestimation of feeding rates. Experimental evidence, however, is scarce. We examined how body size and prey quality affect prey DNA detection success in centipede predators. Due to metabolic rates increasing with body size, we hypothesized that prey DNA detection intervals will be shorter in large predators than in smaller ones. Moreover, we hypothesized that prey detection intervals of high-quality prey, defined by low carbon-to-nitrogen ratio will be shorter than in low-quality prey due to faster assimilation. Small, medium and large individuals of centipedes Lithobius spp. (Lithobiidae, Chilopoda) were fed Collembola and allowed to digest prey for up to 168 h post-feeding. To test our second hypothesis, medium-sized lithobiids were fed with either Diptera or Lumbricidae. No significant differences in 50% prey DNA detection success time intervals for a 272-bp prey DNA fragment were found between the predator size groups, indicating that body size does not affect prey DNA detection success. Post-feeding detection intervals were significantly shorter in Lumbricidae and Diptera compared to Collembola prey, apparently supporting the second hypothesis. However, sensitivity of diagnostic PCR differed between prey types, and quantitative PCR revealed that concentration of targeted DNA varied significantly between prey types. This suggests that both DNA concentration and assay sensitivity need to be considered when assessing prey quality effects on prey DNA detection success. PMID:24383982

  10. Future directions in behavioral headache research: applications for an evolving health care environment.

    PubMed

    Penzien, Donald B; Rains, Jeanetta C; Lipchik, Gay L; Nicholson, Robert A; Lake, Alvin E; Hursey, Karl G

    2005-05-01

    Three decades of research has produced effective behavioral treatments for migraine and tension-type headache, yet the full fruition of this research has not been realized. Further development and dissemination of behavioral treatments is needed to impact the large numbers of those with headache who potentially could benefit from these interventions. At the same time, an evolving health care environment challenges researchers and providers to employ greater efficiency and innovation in managing all chronic disorders. Hopefully, the recently published clinical trials guidelines for behavioral headache research will serve as a catalyst for production of quality empiricism that, in turn, will generate enhanced behavioral strategies and will optimize health care resource utilization. This article describes 10 areas of critical needs and research priorities for behavioral headache research, including: replication and extension of seminal studies using improved methodology; analysis of barriers to implementation of behavioral treatments; development of referral and treatment algorithms; behavioral compliance facilitation with medical interventions; development of a headache self-management model; integration of behavioral intervention within traditional medical practice; identification and management of comorbid psychopathology among headache patients; prevention of disease progression; analysis of behavioral therapeutic mechanisms, and development of innovative treatment formats and applications of information technologies. PMID:15953270

  11. A Bidirectional Relationship between Executive Function and Health Behavior: Evidence, Implications, and Future Directions

    PubMed Central

    Allan, Julia L.; McMinn, David; Daly, Michael

    2016-01-01

    Physically active lifestyles and other health-enhancing behaviors play an important role in preserving executive function into old age. Conversely, emerging research suggests that executive functions facilitate participation in a broad range of healthy behaviors including physical activity and reduced fatty food, tobacco, and alcohol consumption. They do this by supporting the volition, planning, performance monitoring, and inhibition necessary to enact intentions and override urges to engage in health damaging behavior. Here, we focus firstly on evidence suggesting that health-enhancing behaviors can induce improvements in executive function. We then switch our focus to findings linking executive function to the consistent performance of health-promoting behaviors and the avoidance of health risk behaviors. We suggest that executive function, health behavior, and disease processes are interdependent. In particular, we argue that a positive feedback loop may exist whereby health behavior-induced changes in executive function foster subsequent health-enhancing behaviors, which in turn help sustain efficient executive functions and good health. We conclude by outlining the implications of this reciprocal relationship for intervention strategies, the design of research studies, and the study of healthy aging. PMID:27601977

  12. A Bidirectional Relationship between Executive Function and Health Behavior: Evidence, Implications, and Future Directions.

    PubMed

    Allan, Julia L; McMinn, David; Daly, Michael

    2016-01-01

    Physically active lifestyles and other health-enhancing behaviors play an important role in preserving executive function into old age. Conversely, emerging research suggests that executive functions facilitate participation in a broad range of healthy behaviors including physical activity and reduced fatty food, tobacco, and alcohol consumption. They do this by supporting the volition, planning, performance monitoring, and inhibition necessary to enact intentions and override urges to engage in health damaging behavior. Here, we focus firstly on evidence suggesting that health-enhancing behaviors can induce improvements in executive function. We then switch our focus to findings linking executive function to the consistent performance of health-promoting behaviors and the avoidance of health risk behaviors. We suggest that executive function, health behavior, and disease processes are interdependent. In particular, we argue that a positive feedback loop may exist whereby health behavior-induced changes in executive function foster subsequent health-enhancing behaviors, which in turn help sustain efficient executive functions and good health. We conclude by outlining the implications of this reciprocal relationship for intervention strategies, the design of research studies, and the study of healthy aging. PMID:27601977

  13. Effect of light, prey density, and prey type on the feeding rates of Hemimysis anomala

    USGS Publications Warehouse

    Halpin, Kathleen E.; Boscarino, Brent T.; Rudstam, Lars G.; Walsh, Mureen G.; Lantry, Brian F.

    2013-01-01

    Hemimysis anomala is a near-shore mysid native to the Ponto-Caspian region that was discovered to have invaded Great Lakes ecosystems in 2006. We investigated feeding rates and prey preferences of adult and juvenile Hemimysis in laboratory experiments to gain insight on the potential for Hemimysis to disrupt food webs. For both age groups (AGs), we measured feeding rates as a function of prey abundance (Bosmina longirostris as prey), prey type (B. longirostris, Daphnia pulex, and Mesocyclops sp.), and light levels (no light and dim light). Mean feeding rates on Bosmina increased with prey density and reached 23 ind. (2 h)−1 for adults and 17 ind. (2 h)−1 for juveniles. Dim light had little effect on prey selection or feeding rate compared to complete darkness. When feeding rates on alternate prey were compared, both AGs fed at higher rates on Bosmina than Daphnia, but only juveniles fed at significantly higher rates on Bosmina relative to Mesocyclops. No significant differences were observed between feeding rates on Mesocyclops and on Daphnia. Hemimysis feeding rates were on the order of 30–60% of their body weight per day, similar to predatory cladocerans that have been implicated in zooplankton declines in Lakes Huron and Ontario.

  14. Functional response of wolves preying on barren-ground caribou in a multiple-prey ecosystem

    USGS Publications Warehouse

    Dale, B.W.; Adams, Layne G.; Bowyer, R.T.

    1994-01-01

    1. We investigated the functional response of wolves (Canis lupus) to varying abundance of ungulate prey to test the hypothesis that switching from alternate prey to preferred prey results in regulation of a caribou (Rangifer tarandus) population at low densities. 2. We determined prey selection, kill rates, and prey abundance for four wolf packs during three 30-day periods in March 1989, March 1990, November 1990, and created a simple discrete model to evaluate the potential for the expected numerical and observed functional responses of wolves to regulate caribou populations. 3. We observed a quickly decelerating type II functional response that, in the absence of numerical response, implicates an anti-regulatory effect of wolf predation on barren-ground caribou dynamics. 4. There was little potential for regulation caused by the multiplicative effect of increasing functional and numerical responses because of presence of alternative prey. This resulted in high wolf:caribou ratios at low prey densities which precluded the effects of an increasing functional response. 5. Inversely density-dependent predation by other predators, such as bears, reduces the potential for predators to regulate caribou populations at low densities, and small reductions in predation by one predator may have disproportionately large effects on the total predation rate.

  15. Discrimination of visual stimuli representing prey versus non-prey by the praying mantis Sphodromantis lineola (Burr.).

    PubMed

    Prete, F R

    1992-01-01

    Adult, female praying mantids, Sphodromantis lineola (Burr.), were presented with seventy, flat black rectangles which moved toward the mantids (in the horizontal plane) against a white background. The lengths of the lures' edges parallel to their direction of movement, 1(1), were 1.5, 3, 6, 12, 18, 24, 30, 54, 72, or 114 mm; the edge lengths perpendicular to movement direction, 1(2), were 1.5, 3, 6, 12, 18, 24, or 30 mm. Mantids emitted the most predatory behaviors to square lures (1[1] = 1[2]) for which 1(1, 2) = 3-12 mm, and to 'worm' lures (1[1] greater than 1[2]) for which 1(2) = 1.5-6 mm. 'Anti-worm' lures (1[1] less than 1[2]) were poor releasers of predatory behavior. These results reconcile seemingly discrepant findings between studies that have presented mantids with various types of oscillating, rotating and/or three-dimensional lures. Further, the results indicate that like other terrestrial predators, such as toads, prey recognition by S. lineola is approximate and based on the spatiotemporal relationships between the features of moving objects (i.e. worm versus anti-worm). These findings are congruent with data on mantid prey selection in the wild. PMID:1498650

  16. Parasites as prey in aquatic food webs: implications for predator infection and parasite transmission

    USGS Publications Warehouse

    Thieltges, David W.; Amundsen, Per-Arne; Hechinger, Ryan F.; Johnson, Pieter T.J.; Lafferty, Levin D.; Mouritsen, Kim N.; Preston, Daniel L.; Reise, Karsten; Zander, C. Dieter; Poulin, Robert

    2013-01-01

    While the recent inclusion of parasites into food-web studies has highlighted the role of parasites as consumers, there is accumulating evidence that parasites can also serve as prey for predators. Here we investigated empirical patterns of predation on parasites and their relationships with parasite transmission in eight topological food webs representing marine and freshwater ecosystems. Within each food web, we examined links in the typical predator–prey sub web as well as the predator–parasite sub web, i.e. the quadrant of the food web indicating which predators eat parasites. Most predator– parasite links represented ‘concomitant predation’ (consumption and death of a parasite along with the prey/host; 58–72%), followed by ‘trophic transmission’ (predator feeds on infected prey and becomes infected; 8–32%) and predation on free-living parasite life-cycle stages (4–30%). Parasite life-cycle stages had, on average, between 4.2 and 14.2 predators. Among the food webs, as predator richness increased, the number of links exploited by trophically transmitted parasites increased at about the same rate as did the number of links where these stages serve as prey. On the whole, our analyses suggest that predation on parasites has important consequences for both predators and parasites, and food web structure. Because our analysis is solely based on topological webs, determining the strength of these interactions is a promising avenue for future research.

  17. Prey composition and ontogenetic shift in coastal populations of longnose gar Lepisosteus osseus.

    PubMed

    Smylie, M; Shervette, V; McDonough, C

    2015-10-01

    Longnose gar Lepisosteus osseus were collected from May 2012 to July 2013 in the Charleston Harbor and Winyah Bay estuaries (SC, U.S.A.). This study examined trends in stomach fullness, described major prey components and their importance in the diet of L. osseus, compared stomach content-based trophic level estimates with the stable-isotope-based proxy: δ(15) N and tested for the occurrence of an ontogenetic diet shift using stomach content analysis and stable C and N isotopes (δ(13) C and δ(15) N). Dominant prey families were Clupeidae, Sciaenidae, Penaeidae, Fundulidae and Mugilidae, with the highest consumption rates in autumn. Trophic levels calculated using stomach contents did not correspond to δ(15) N (P > 0·05). Stomach contents and stable-isotope signatures indicate ontogenetic prey composition shifts from low trophic level benthic prey (fundulids) to higher trophic level pelagic prey (clupeids) as the fish grow between 400 and 600 mm in standard length. Due to their biomass, abundance and top predator status, L. osseus play a significant ecological role in the estuarine community composition, although this effect has often been overlooked by past researchers and should be considered in future estuarine community studies. PMID:26299941

  18. Dynamics of a prey-predator system under Poisson white noise excitation

    NASA Astrophysics Data System (ADS)

    Pan, Shan-Shan; Zhu, Wei-Qiu

    2014-10-01

    The classical Lotka-Volterra (LV) model is a well-known mathematical model for prey-predator ecosystems. In the present paper, the pulse-type version of stochastic LV model, in which the effect of a random natural environment has been modeled as Poisson white noise, is investigated by using the stochastic averaging method. The averaged generalized Itô stochastic differential equation and Fokker-Planck-Kolmogorov (FPK) equation are derived for prey-predator ecosystem driven by Poisson white noise. Approximate stationary solution for the averaged generalized FPK equation is obtained by using the perturbation method. The effect of prey self-competition parameter ɛ2 s on ecosystem behavior is evaluated. The analytical result is confirmed by corresponding Monte Carlo (MC) simulation.

  19. Behavior Breakthroughs[TM]: Future Teachers Reflect on a Focused Game Designed to Teach ABA Techniques

    ERIC Educational Resources Information Center

    Lowdermilk, John; Martinez, Deborah; Pecina, Julie; Beccera, Lisa; Lowdermilk, Carey

    2012-01-01

    This article examines the use of a focused educational game. The game, "Behavior Breakthroughs"[TM], was created to teach people that work with children with autism, appropriate behavior management techniques. A group of undergraduate, teacher education students played the game and provided feedback on their experiences.

  20. The Application of SEM to Behavioral Research in Oncology: Past Accomplishments and Future Opportunities

    ERIC Educational Resources Information Center

    Schnoll, Robert A.; Fang, Carolyn Y.; Manne, Sharon L.

    2004-01-01

    The past decade has seen a tremendous growth in the use of structural equation modeling (SEM) to address research questions in 2 subfields of behavioral science: cancer prevention and control (e.g., determinants of cancer screening adherence) and behavioral oncology (e.g., determinants of psychosocial adjustment among cancer patients or…

  1. Managing Aggression Using Cognitive-Behavioral Interventions: State of the Practice and Future Directions

    ERIC Educational Resources Information Center

    Smith, Stephen W.; Lochman, John E.; Daunic, Ann P.

    2005-01-01

    Education professionals consistently rank disruptive/aggressive student behavior as persistent and troubling, reporting various types of maladaptive behaviors ranging from talking out in class to assault. Researchers suggest that childhood aggression accounts for a high proportion of the referrals to special education for emotional and behavioral…

  2. Direct Observation of Teacher and Student Behavior in School Settings: Trends, Issues and Future Directions

    ERIC Educational Resources Information Center

    Lewis, Timothy J.; Scott, Terrance M.; Wehby, Joseph H.; Wills, Howard P.

    2014-01-01

    Across the modern history of the field of special education and emotional/behavioral disorders (EBD), direct observation of student and educator behavior has been an essential component of the diagnostic process, student progress monitoring, and establishing functional and statistical relationships within research. This article provides an…

  3. Academic Engagement of Students with Emotional and Behavioral Disorders: Existing Research, Issues, and Future Directions

    ERIC Educational Resources Information Center

    Al-Hendawi, Maha

    2012-01-01

    Academic engagement is a multidimensional construct that is gaining increasing attention in education as a means of promoting positive academic and social behavior outcomes for diverse learners across all levels of education. However, this review revealed that research on academic engagement of students with emotional and behavioral disorders…

  4. Recent Research on Emergent Verbal Behavior: Clinical Applications and Future Directions

    ERIC Educational Resources Information Center

    Grow, Laura L.; Kodak, Tiffany

    2010-01-01

    Previous research on the acquisition of verbal behavior in children with developmental disabilities has focused on teaching four primary verbal operants: (1) "mand"; (2) "tact"; (3) "echoic"; and (4) "intraverbal". In Skinner's (1957) analysis of verbal behavior, he stated that each verbal operant is maintained by unique antecedent and consequence…

  5. Unintended facilitation between marine consumers generates enhanced mortality for their shared prey.

    PubMed

    Fodrie, F Joel; Kenworthy, Matthew D; Powers, Sean P

    2008-12-01

    We manipulated predator densities and prey vulnerability to explore how interactions between two predators affect overall mortality of their shared prey. Our three-member study system included eastern oysters (Crassostrea virginica) and two of its major consumers: southern oyster drills (Stramonita haemastoma) and stone crabs (Menippe adina). Field experiments demonstrated that drills and crabs foraging together generated higher than expected oyster mortality based on each species operating independently, even though crabs also killed some drills. In subsequent laboratory trials, we experimentally mimicked the handling of oysters by foraging crabs and confirmed that crabs facilitated drills by breeching oyster valves, thereby granting easy access for drills to their prey. Facilitation between co-occurring predators is uncommon and typically occurs because the behavior or habitat selection of a prey species is altered by the presence of one predator, consequently making the prey more susceptible to another predator. Whereas oysters are sedentary regardless of the predator field, we observed an entirely different mechanism that resulted in predator facilitation. This involved direct attacks on the physical defenses of oysters by one predator that ultimately increased the overall consumption rate of foraging species. These dynamics significantly enhanced mortality risk for a foundation species within an estuarine ecosystem. PMID:19137933

  6. Predator-Prey Interactions Shape Thermal Patch Use in a Newt Larvae-Dragonfly Nymph Model

    PubMed Central

    Gvoždík, Lumír; Černická, Eva; Van Damme, Raoul

    2013-01-01

    Thermal quality and predation risk are considered important factors influencing habitat patch use in ectothermic prey. However, how the predator’s food requirement and the prey’s necessity to avoid predation interact with their respective thermoregulatory strategies remains poorly understood. The recently developed ‘thermal game model’ predicts that in the face of imminent predation, prey should divide their time equally among a range of thermal patches. In contrast, predators should concentrate their hunting activities towards warmer patches. In this study, we test these predictions in a laboratory setup and an artificial environment that mimics more natural conditions. In both cases, we scored thermal patch use of newt larvae (prey) and free-ranging dragonfly nymphs (predators). Similar effects were seen in both settings. The newt larvae spent less time in the warm patch if dragonfly nymphs were present. The patch use of the dragonfly nymphs did not change as a function of prey availability, even when the nymphs were starved prior to the experiment. Our behavioral observations partially corroborate predictions of the thermal game model. In line with asymmetric fitness pay-offs in predator-prey interactions (the ‘life-dinner’ principle), the prey’s thermal strategy is more sensitive to the presence of predators than vice versa. PMID:23755175

  7. Cognitive-Behavioral Therapy for PTSD and Depression Symptoms Reduces Risk for Future Intimate Partner Violence among Interpersonal Trauma Survivors

    PubMed Central

    Iverson, Katherine M.; Gradus, Jaimie L.; Resick, Patricia A.; Suvak, Michael K.; Smith, Kamala F.; Monson, Candice M.

    2010-01-01

    Objective Women who develop symptoms of posttraumatic stress disorder (PTSD) and depression subsequent to interpersonal trauma are at heightened risk for future intimate partner violence (IPV) victimization. Cognitive-behavioral therapy (CBT) is effective in reducing PTSD and depression symptoms, yet limited research has investigated the effectiveness of cognitive-behavior therapy in reducing risk for future IPV among interpersonal trauma survivors. Method This study examined the effect of CBT for PTSD and depressive symptoms on the risk of future IPV victimization in a sample of women survivors of interpersonal violence. The current sample included 150 women diagnosed with PTSD secondary to an array of interpersonal traumatic events who were participating in a randomized clinical trial of different forms of cognitive processing therapy for the treatment of PTSD. Participants were assessed at nine time points as part of the larger trial: pre-treatment, six times during treatment, post-treatment, and at 6-month follow-up. Results As hypothesized, reductions in both PTSD and depressive symptoms during treatment were associated with a decreased likelihood of IPV victimization at a 6-month follow-up even after controlling for recent IPV (i.e., IPV from a current partner within the year prior to beginning the study) and prior interpersonal traumas. Conclusions These findings highlight the importance of identifying and treating PTSD and depressive symptoms among interpersonal trauma survivors as a method for reducing risk for future IPV. PMID:21341889

  8. Population and Evolutionary Dynamics based on Predator-Prey Relationships in a 3D Physical Simulation.

    PubMed

    Ito, Takashi; Pilat, Marcin L; Suzuki, Reiji; Arita, Takaya

    2016-01-01

    Recent studies have reported that population dynamics and evolutionary dynamics, occurring at different time scales, can be affected by each other. Our purpose is to explore the interaction between population and evolutionary dynamics using an artificial life approach based on a 3D physically simulated environment in the context of predator-prey and morphology-behavior coevolution. The morphologies and behaviors of virtual prey creatures are evolved using a genetic algorithm based on the predation interactions between predators and prey. Both population sizes are also changed, depending on the fitness. We observe two types of cyclic behaviors, corresponding to short-term and long-term dynamics. The former can be interpreted as a simple population dynamics of Lotka-Volterra type. It is shown that the latter cycle is based on the interaction between the changes in the prey strategy against predators and the long-term change in both population sizes, resulting partly from a tradeoff between their defensive success and the cost of defense. PMID:26934093

  9. Prey escaping wolves, Canis lupus, despite close proximity

    USGS Publications Warehouse

    Nelson, M.E.; Mech, L.D.

    1993-01-01

    We describe attacks by wolf (Canis lupus) packs in Minnesota on a white-tailed deer (Odocoileus virginianus) and a moose (Alces alces) in which wolves were within contact distance of the prey but in which the prey escaped.

  10. Movements of wintering surf scoters: predator responses to different prey landscapes.

    PubMed

    Kirk, Molly; Esler, Daniel; Iverson, Samuel A; Boyd, W Sean

    2008-04-01

    The distribution of predators is widely recognized to be intimately linked to the distribution of their prey. Foraging theory suggests that predators will modify their behaviors, including movements, to optimize net energy intake when faced with variation in prey attributes or abundance. While many studies have documented changes in movement patterns of animals in response to temporal changes in food, very few have contrasted movements of a single predator species naturally occurring in dramatically different prey landscapes. We documented variation in the winter movements, foraging range size, site fidelity, and distribution patterns of a molluscivorous sea duck, the surf scoter (Melanitta perspicillata), in two areas of coastal British Columbia with very different shellfish prey features. Baynes Sound has extensive tidal flats with abundant clams, which are high-quality and temporally stable prey for scoters. Malaspina Inlet is a rocky fjord-like inlet where scoters consume mussels that are superabundant and easily accessible in some patches but are heavily depleted over the course of winter. We used radio telemetry to track surf scoter movements in both areas and found that in the clam habitats of Baynes Sound, surf scoters exhibited limited movement, small winter ranges, strong foraging site fidelity, and very consistent distribution patterns. By contrast, in mussel habitats in the Malaspina Inlet, surf scoters displayed more movement, larger ranges, little fidelity to specific foraging sites, and more variable distribution patterns. We conclude that features associated with the different prey types, particularly the higher depletion rates of mussels, strongly influenced seasonal space use patterns. These findings are consistent with foraging theory and confirm that predator behavior, specifically movements, is environmentally mediated. PMID:18210158

  11. A single predator charging a herd of prey: effects of self volume and predator–prey decision-making

    NASA Astrophysics Data System (ADS)

    Schwarzl, Maria; Godec, Aljaz; Oshanin, Gleb; Metzler, Ralf

    2016-06-01

    We study the degree of success of a single predator hunting a herd of prey on a two-dimensional square lattice landscape. We explicitly consider the self volume of the prey restraining their dynamics on the lattice. The movement of both predator and prey is chosen to include an intelligent, decision making step based on their respective sighting ranges, the radius in which they can detect the other species (prey cannot recognise each other besides the self volume interaction): after spotting each other the motion of prey and predator turns from a nearest neighbour random walk into directed escape or chase, respectively. We consider a large range of prey densities and sighting ranges and compute the mean first passage time for a predator to catch a prey as well as characterise the effective dynamics of the hunted prey. We find that the prey's sighting range dominates their life expectancy and the predator profits more from a bad eyesight of the prey than from his own good eye sight. We characterise the dynamics in terms of the mean distance between the predator and the nearest prey. It turns out that effectively the dynamics of this distance coordinate can be captured in terms of a simple Ornstein–Uhlenbeck picture. Reducing the many-body problem to a simple two-body problem by imagining predator and nearest prey to be connected by an effective Hookean bond, all features of the model such as prey density and sighting ranges merge into the effective binding constant.

  12. Diet, prey delivery rates, and prey biomass of Northern Goshawks in East-Central Arizona

    USGS Publications Warehouse

    Rogers, A.S.; DeStefano, S.; Ingraldi, M.F.

    2006-01-01

    Recent concern over persistence of Northern Goshawk (Accipiter gentilis) populations in Arizona has stemmed from two long-term demography studies that report substantial yearly fluctuations in productivity and evidence of a declining population. Although many factors could be involved in changes in productivity and population declines, availability of food is one such factor. As part of a demography study on the Sitgreaves portion of the Apache-Sitgreaves National Forest in Arizona, we used remote cameras to assess diets of goshawks. Northern Goshawks preyed upon 22 species during two nesting seasons. Adult pairs tended to specialize on particular species of prey. Prey delivery rates decreased throughout the nesting season with a corresponding increase in biomass in the latter stages of the nestling and fledgling periods. Adults appeared to take larger prey as nestlings increased in age.

  13. Influence of edge on predator prey distribution and abundance

    NASA Astrophysics Data System (ADS)

    Ferguson, Steven H.

    2004-03-01

    I investigated the effect of spatial configuration on distribution and abundance of invertebrate trophic groups by counting soil arthropods under boxes (21 × 9.5 cm) arranged in six different patterns that varied in the amount of edge (137-305 cm). I predicted fewer individuals from the consumer trophic group (Collembola) in box groups with greater amount of edge. This prediction was based on the assumption that predators (mites, ants, spiders, centipedes) select edge during foraging and thereby reduce abundance of the less mobile consumer group under box patterns with greater edge. Consumer abundance (Collembola) was not correlated with amount of edge. Among the predator groups, mite, ant and centipede abundance related to the amount of edge of box groups. However, in contrast to predictions, abundance of these predators was negatively correlated with amount of edge in box patterns. All Collembola predators, with the exception of ants, were less clumped in distribution than Collembola. The results are inconsistent with the view that predators used box edges to predate the less mobile consumer trophic group. Alternative explanations for the spatial patterns other than predator-prey relations include (1) a negative relationship between edge and moisture, (2) a positive relationship between edge and detritus decomposition (i.e. mycelium as food for the consumer group), and (3) a negative relationship between edge and the interstices between adjacent boxes. Landscape patterns likely affect microclimate, food, and predator-prey relations and, therefore, future experimental designs need to control these factors individually to distinguish among alternative hypotheses.

  14. A predator-prey model with diseases in both prey and predator

    NASA Astrophysics Data System (ADS)

    Gao, Xubin; Pan, Qiuhui; He, Mingfeng; Kang, Yibin

    2013-12-01

    In this paper, we present and analyze a predator-prey model, in which both predator and prey can be infected. Each of the predator and prey is divided into two categories, susceptible and infected. The epidemics cannot be transmitted between prey and predator by predation. The predation ability of susceptible predators is stronger than infected ones. Likewise, it is more difficult to catch a susceptible prey than an infected one. And the diseases cannot be hereditary in both of the predator and prey populations. Based on the assumptions above, we find that there are six equilibrium points in this model. Using the base reproduction number, we discuss the stability of the equilibrium points qualitatively. Then both of the local and global stabilities of the equilibrium points are analyzed quantitatively by mathematical methods. We provide numerical results to discuss some interesting biological cases that our model exhibits. Lastly, we discuss how the infectious rates affect the stability, and how the other parameters work in the five possible cases within this model.

  15. Alterations in prey capture and induction of metallothioneins in grass shrimp fed cadmium-contaminated prey

    SciTech Connect

    Wallace, W.G.; Hoexum Brouwer, T.M.; Brouwer, M.; Lopez, G.R.

    2000-04-01

    The aquatic oligochaete Limnodrilus hoffmeisteri from a Cd-contaminated cove on the Hudson River, Foundry Cove, New York, USA, has evolved Cd resistance. Past studies have focused on how the mode of detoxification of Cd by these Cd-resistant worms influences Cd trophic transfer to the grass shrimp Palaemonetes pugio. In the present study, the authors investigate reductions in prey capture in grass shrimp fed Cd-contaminated prey. They also investigate the induction of metal-binding proteins, metallothioneins, in these Cd-exposed shrimp. Grass shrimp were fed field-exposed Cd-contaminated Foundry Cove oligochaetes or laboratory-exposed Cd-contaminated Artemia salina. Following these exposures, the ability of Cd- dosed and control shrimp to capture live A. salina was compared. Results show that shrimp fed laboratory-exposed Cd-contaminated A. salina for 2 weeks exhibit significant reductions in their ability to successfully capture prey (live A. salina). Reductions in prey capture were also apparent, though not as dramatic in shrimp fed for 1 week on field-exposed Cd-contained Foundry Cove oligochaetes. Shrimp were further investigated for their subcellular distribution of Cd to examine if alterations in prey capture could be linked to saturation of Cd-metallothionein. Cd-dosed shrimp produced a low molecular weight CD-binding metallothionein protein in a dose- and time-dependent manner. Most importantly, successful prey capture decreased with increased Cd body burdens and increased Cd concentration bound to high molecular weight proteins.

  16. The future of behavioral sleep medicine: a report on the presentations given at the Ponte Vedra Behavioral Sleep Medicine Consensus Conference, March 27-29, 2009.

    PubMed

    McCrae, Christina S; Taylor, Daniel J; Smith, Michael T; Perlis, Michael L

    2010-01-01

    A major goal of the Behavioral Sleep Medicine Consensus Conference held in Ponte Vedra, Florida on March 27 through 29, 2009 was to have 15 key opinion leaders provide the latest information on their areas of expertise. Those leaders represented the breadth of the behavioral sleep medicine field (pediatrics, adults, insomnia, PAP adherence, and circadian rhythm disorders) and included clinicians and researchers from a variety of settings (academia, private practice, the military, and primary care). The presentations highlighted the milestones already achieved by the field (critical mass, solid empirical base, 30+ training programs, certification, dedicated journal, and dedicated textbook), as well as important future directions (more clinical research, public relations campaigns, training, and reimbursement). PMID:20352544

  17. Parenting styles and practices in children's obesogenic behaviors: scientific gaps and future research directions.

    PubMed

    Patrick, Heather; Hennessy, Erin; McSpadden, Kate; Oh, April

    2013-08-01

    Given the emerging global childhood obesity epidemic and the specter of a generation of children who will have a shorter life expectancy than that of their parents, recent research has focused on factors that influence children's weight status and obesogenic behaviors (i.e., eating, physical activity, and screen media use). Parents act as primary socializing agents for children, and thus growing evidence supports the role of parenting styles and practices in children's obesity-related behaviors and weight. Studying these processes in children and adolescents is important for several reasons. First, diet and physical activity behaviors and weight status track from childhood and adolescence into adulthood. Furthermore, diet and physical activity behaviors and weight status confer significant risk for cancer, diabetes, cardiovascular disease, and other chronic diseases. The purpose of this article is to describe the scientific gaps that need to be addressed to develop a more informed literature on parenting styles and practices in the domains of weight status and obesogenic behaviors, as identified by an expert panel assembled by the National Cancer Institute. PMID:23944926

  18. Parenting Styles and Practices in Children's Obesogenic Behaviors: Scientific Gaps and Future Research Directions

    PubMed Central

    Hennessy, Erin; McSpadden, Kate; Oh, April

    2013-01-01

    Abstract Given the emerging global childhood obesity epidemic and the specter of a generation of children who will have a shorter life expectancy than that of their parents, recent research has focused on factors that influence children's weight status and obesogenic behaviors (i.e., eating, physical activity, and screen media use). Parents act as primary socializing agents for children, and thus growing evidence supports the role of parenting styles and practices in children's obesity-related behaviors and weight. Studying these processes in children and adolescents is important for several reasons. First, diet and physical activity behaviors and weight status track from childhood and adolescence into adulthood. Furthermore, diet and physical activity behaviors and weight status confer significant risk for cancer, diabetes, cardiovascular disease, and other chronic diseases. The purpose of this article is to describe the scientific gaps that need to be addressed to develop a more informed literature on parenting styles and practices in the domains of weight status and obesogenic behaviors, as identified by an expert panel assembled by the National Cancer Institute. PMID:23944926

  19. Counterfactual and Factual Reflection: The Influence of Past Misdeeds on Future Immoral Behavior.

    PubMed

    Gaspar, Joseph P; Seabright, Mark A; Reynolds, Scott J; Yam, Kai Chi

    2015-01-01

    Though the decision to behave immorally is situated within the context of prior immoral behavior, research has provided contradictory insights into this process. In a series of experiments, we demonstrate that the effects of prior immoral behavior depend on how individuals think about, or reflect on, their immoral behavior. In Experiment 1, participants who reflected counterfactually on their prior moral lapses morally disengaged (i.e., rationalized) less than participants who reflected factually. In Experiment 2, participants who reflected counterfactually on their prior moral lapses experienced more guilt than those who reflected factually. Finally, in Experiments 3 and 4, participants who reflected counterfactually lied less on unrelated tasks with real monetary stakes than those who reflected factually. Our studies provide important insights into moral rationalization and moral compensation processes and demonstrate the profound influence of reflection in everyday moral life. PMID:25668142

  20. Moorea BIOCODE barcode library as a tool for understanding predator-prey interactions: insights into the diet of common predatory coral reef fishes

    NASA Astrophysics Data System (ADS)

    Leray, M.; Boehm, J. T.; Mills, S. C.; Meyer, C. P.

    2012-06-01

    Identifying species involved in consumer-resource interactions is one of the main limitations in the construction of food webs. DNA barcoding of prey items in predator guts provides a valuable tool for characterizing trophic interactions, but the method relies on the availability of reference sequences to which prey sequences can be matched. In this study, we demonstrate that the COI sequence library of the Moorea BIOCODE project, an ecosystem-level barcode initiative, enables the identification of a large proportion of semi-digested fish, crustacean and mollusks found in the guts of three Hawkfish and two Squirrelfish species. While most prey remains lacked diagnostic morphological characters, 94% of the prey found in 67 fishes had >98% sequence similarity with BIOCODE reference sequences. Using this species-level prey identification, we demonstrate how DNA barcoding can provide insights into resource partitioning, predator feeding behaviors and the consequences of predation on ecosystem function.

  1. Echolocating bats use future-target information for optimal foraging.

    PubMed

    Fujioka, Emyo; Aihara, Ikkyu; Sumiya, Miwa; Aihara, Kazuyuki; Hiryu, Shizuko

    2016-04-26

    When seeing or listening to an object, we aim our attention toward it. While capturing prey, many animal species focus their visual or acoustic attention toward the prey. However, for multiple prey items, the direction and timing of attention for effective foraging remain unknown. In this study, we adopted both experimental and mathematical methodology with microphone-array measurements and mathematical modeling analysis to quantify the attention of echolocating bats that were repeatedly capturing airborne insects in the field. Here we show that bats select rational flight paths to consecutively capture multiple prey items. Microphone-array measurements showed that bats direct their sonar attention not only to the immediate prey but also to the next prey. In addition, we found that a bat's attention in terms of its flight also aims toward the next prey even when approaching the immediate prey. Numerical simulations revealed a possibility that bats shift their flight attention to control suitable flight paths for consecutive capture. When a bat only aims its flight attention toward its immediate prey, it rarely succeeds in capturing the next prey. These findings indicate that bats gain increased benefit by distributing their attention among multiple targets and planning the future flight path based on additional information of the next prey. These experimental and mathematical studies allowed us to observe the process of decision making by bats during their natural flight dynamics. PMID:27071082

  2. Echolocating bats use future-target information for optimal foraging

    PubMed Central

    Fujioka, Emyo; Aihara, Ikkyu; Sumiya, Miwa; Aihara, Kazuyuki; Hiryu, Shizuko

    2016-01-01

    When seeing or listening to an object, we aim our attention toward it. While capturing prey, many animal species focus their visual or acoustic attention toward the prey. However, for multiple prey items, the direction and timing of attention for effective foraging remain unknown. In this study, we adopted both experimental and mathematical methodology with microphone-array measurements and mathematical modeling analysis to quantify the attention of echolocating bats that were repeatedly capturing airborne insects in the field. Here we show that bats select rational flight paths to consecutively capture multiple prey items. Microphone-array measurements showed that bats direct their sonar attention not only to the immediate prey but also to the next prey. In addition, we found that a bat’s attention in terms of its flight also aims toward the next prey even when approaching the immediate prey. Numerical simulations revealed a possibility that bats shift their flight attention to control suitable flight paths for consecutive capture. When a bat only aims its flight attention toward its immediate prey, it rarely succeeds in capturing the next prey. These findings indicate that bats gain increased benefit by distributing their attention among multiple targets and planning the future flight path based on additional information of the next prey. These experimental and mathematical studies allowed us to observe the process of decision making by bats during their natural flight dynamics. PMID:27071082

  3. Translational Research in Behavior Analysis: Historical Traditions and Imperative for the Future

    PubMed Central

    Mace, F. Charles; Critchfield, Thomas S

    2010-01-01

    “Pure basic” science can become detached from the natural world that it is supposed to explain. “Pure applied” work can become detached from fundamental processes that shape the world it is supposed to improve. Neither demands the intellectual support of a broad scholarly community or the material support of society. Translational research can do better by seeking innovation in theory or practice through the synthesis of basic and applied questions, literatures, and methods. Although translational thinking has always occurred in behavior analysis, progress often has been constrained by a functional separation of basic and applied communities. A review of translational traditions in behavior analysis suggests that innovation is most likely when individuals with basic and applied expertise collaborate. Such innovation may have to accelerate for behavior analysis to be taken seriously as a general-purpose science of behavior. We discuss the need for better coordination between the basic and applied sectors, and argue that such coordination compromises neither while benefiting both. PMID:21119847

  4. The Education of Students with Emotional and Behavior Disabilities in Australia: Current Trends and Future Directions

    ERIC Educational Resources Information Center

    Cumming, Therese M.

    2012-01-01

    A discussion about the current state of special education, more specifically the field of emotional and behavior disabilities (EBD), in Australia cannot take place without first providing an overview of the Australian education system. Education comes under the jurisdiction of state and territory responsibility. The federal government coordinates…

  5. The Behavior Chain Interruption Strategy: A Review of Research and Discussion of Future Directions.

    ERIC Educational Resources Information Center

    Carter, Mark; Grunsell, Julie

    2001-01-01

    A review of 10 studies that utilize the behavior chain interruption strategy (BCIS) to teach communication skills to individuals with severe disabilities found that BCIS has been successfully applied to individuals across a wide range of ages and levels of disability, including learners with multiple disabilities. Generalization concerns are…

  6. Carnivore repatriation and holarctic prey: narrowing the deficit in ecological effectiveness.

    PubMed

    Berger, Joel

    2007-08-01

    The continuing global decline of large carnivores has catalyzed great interest in reintroduction to restore populations and to reestablish ecologically functional relationships. I used variation in the distribution of four Holarctic prey species and their behavior as proxies to investigate the pace and intensity by which responses are lost or reinvigorated by carnivore repatriation. By simulating the presence of wolves (Canis lupus), tigers (Panthera tigris), and brown bears (Ursus arctos) at 19 transcontinental sites, I assayed three metrics of prey performance in areas with no large terrestrial carnivores (the polar islands of Greenland and Svalbard), extant native carnivores (Eastern Siberian Shield, boreal Canada, and Alaska); and repatriated carnivores (the Yellowstone region and Rocky Mountains). The loss and reestablishment of large carnivores changed the ecological effectiveness of systems by (1) dampening immediate group benefits, diminishing awareness, and diminishing flight reaction in caribou (Rangifer tarandus) where predation was eliminated and (2) reinstituting sensitivity to carnivores by elk (Cervus elaphus) and moose (Alces alces) in the Yellowstone region to levels observed in Asian elk when sympatric with Siberian tigers and wolves or in Alaskan moose sympatric with wolves. Behavioral compensation to reintroduced carnivores occurred within a single generation, but only the vigilance reaction of bison (Bison bison) in Yellowstone exceeded that of their wolf-exposed conspecifics from boreal Canada. Beyond these overt responses by prey, snow depth and distance to suitably vegetated habitat was related to heightened vigilance in moose and elk, respectively, but only at sites with carnivores. These findings are insufficient to determine whether similar patterns might apply to other species or in areas with alien predators, and they suggest that the presumed excessive vulnerability of naïve prey to repatriated carnivores may be ill-founded. Although

  7. Body size matters for aposematic prey during predator aversion learning.

    PubMed

    Smith, Karen E; Halpin, Christina G; Rowe, Candy

    2014-11-01

    Aposematic prey advertise their toxicity to predators using conspicuous warning signals, which predators learn to use to reduce their intake of toxic prey. Like other types of prey, aposematic prey often differ in body size, both within and between species. Increasing body size can increase signal size, which make larger aposematic prey more detectable but also gives them a more effective and salient deterrent. However, increasing body size also increases the nutritional value of prey, and larger aposematic prey may make a more profitable meal to predators that are trading off the costs of eating toxins with the benefits of ingesting nutrients. We tested if body size, independent of signal size, affected predation of toxic prey as predators learn to reduce their attacks on them. European starlings (Sturnus vulgaris) learned to discriminate between defended (quinine-injected) and undefended (water-injected) mealworm prey (Tenebrio molitor) using visual signals. During this process, we found that birds attacked and ate more defended prey the larger they were. Body size does affect the probability that toxic prey are attacked and eaten, which has implications for the evolutionary dynamics of aposematism and mimicry (where species share the same warning pattern). PMID:25256160

  8. Intense or Spatially Heterogeneous Predation Can Select against Prey Dispersal

    PubMed Central

    Barraquand, Frederic; Murrell, David J.

    2012-01-01

    Dispersal theory generally predicts kin competition, inbreeding, and temporal variation in habitat quality should select for dispersal, whereas spatial variation in habitat quality should select against dispersal. The effect of predation on the evolution of dispersal is currently not well-known: because predation can be variable in both space and time, it is not clear whether or when predation will promote dispersal within prey. Moreover, the evolution of prey dispersal affects strongly the encounter rate of predator and prey individuals, which greatly determines the ecological dynamics, and in turn changes the selection pressures for prey dispersal, in an eco-evolutionary feedback loop. When taken all together the effect of predation on prey dispersal is rather difficult to predict. We analyze a spatially explicit, individual-based predator-prey model and its mathematical approximation to investigate the evolution of prey dispersal. Competition and predation depend on local, rather than landscape-scale densities, and the spatial pattern of predation corresponds well to that of predators using restricted home ranges (e.g. central-place foragers). Analyses show the balance between the level of competition and predation pressure an individual is expected to experience determines whether prey should disperse or stay close to their parents and siblings, and more predation selects for less prey dispersal. Predators with smaller home ranges also select for less prey dispersal; more prey dispersal is favoured if predators have large home ranges, are very mobile, and/or are evenly distributed across the landscape. PMID:22247764

  9. Nonadditive impacts of temperature and basal resource availability on predator-prey interactions and phenotypes.

    PubMed

    Costa, Zacharia J; Kishida, Osamu

    2015-08-01

    Predicting the impacts of climate change on communities requires understanding how temperature affects predator-prey interactions under different biotic conditions. In cases of size-specific predation, environmental influences on the growth rate of one or both species can determine predation rates. For example, warming increases top-down control of food webs, although this depends on resource availability for prey, as increased resources may allow prey to reach a size refuge. Moreover, because the magnitude of inducible defenses depends on predation rates and resource availability for prey, temperature and resource levels also affect phenotypic plasticity. To examine these issues, we manipulated the presence/absence of predatory Hynobius retardatus salamander larvae and herbivorous Rana pirica tadpoles at two temperatures and three basal resource levels. and measured their morphology, behavior, growth and survival. Prior work has shown that both species express antagonistic plasticity against one another in which salamanders enlarge their gape width and tadpoles increase their body width to reach a size-refuge. We found that increased temperatures increased predation rates, although this was counteracted by high basal resource availability, which further decreased salamander growth. Surprisingly, salamanders caused tadpoles to grow larger and express more extreme defensive phenotypes as resource levels decreased under warming, most likely due to their increased risk of predation. Thus, temperature and resources influenced defensive phenotype expression and its impacts on predator and prey growth by affecting their interaction strength. Our results indicate that basal resource levels can modify the impacts of increased temperatures on predator-prey interactions and its consequences for food webs. PMID:25820751

  10. Enhancements to the behavioral parent training paradigm for families of children with ADHD: review and future directions.

    PubMed

    Chronis, Andrea M; Chacko, Anil; Fabiano, Gregory A; Wymbs, Brian T; Pelham, William E

    2004-03-01

    Behavioral parent training (BPT) is one of the empirically supported psychosocial treatments for ADHD. Over many years and in many studies, BPT has been documented to improve both child ADHD behavior and maladaptive parenting behavior. In some studies, BPT has also been found to result in benefits in additional domains, such as parenting stress and child classroom behavior. However, the BPT literature on children selected as having ADHD lags behind research conducted on BPT for children selected as having oppositional defiant and conduct disorders (ODD and CD, respectively) with regard to examination of factors that may limit treatment attainment, compliance, and outcomes, such as single parenthood, parental psychopathology, and child comorbidity. Because of the high degree of comorbidity between ADHD and ODD/CD, it is difficult to separate the two BPT literatures. The parameters of BPT (e.g.. format and setting), parent factors, and child factors that may contribute to treatment outcomes for families of children with ADHD are reviewed here and recommendations for future BPT research in the area of ADHD are made. PMID:15119686

  11. Rich dynamic of a stage-structured prey-predator model with cannibalism and periodic attacking rate

    NASA Astrophysics Data System (ADS)

    Zhang, Limin; Zhang, Chaofeng

    2010-12-01

    The dynamic behavior of a stage-structure prey-predator model with cannibalism for prey and periodic attacking rate for predator is investigated. Firstly, the permanence, locally and globally asymptotic stability analyses of the model with constant attacking rate are explored. After that, sufficient conditions for the permanence of the corresponding nonautonomous system with periodic attacking rate are obtained. Furthermore, numerical simulations are presented to illustrate the effects of periodic attacking rate. Simulation results show that the system with periodic attacking rate shows a rich behaviors, including period-doubling and period-having bifurcations, chaos and windows of periodicity.

  12. The brain and behavior of the tentacled snake.

    PubMed

    Catania, Kenneth C

    2011-04-01

    Tentacled snakes (Erpeton tentaculatum) are aquatic predators that feed exclusively on fish. They have a unique pair of tentacles projecting from the face and an unusual J-shaped hunting posture. These features have been the subject of speculation for over a century. In a series of behavioral studies, tentacled snakes were found to exploit fish escape responses by startling fish toward their strike. This remarkable, deceptive behavior takes advantage of the stereotyped C-start escape response of fish. For some fish approach angles, snakes predicted future fish behavior and accurately struck at their moving head. These findings suggest tentacled snakes are acting as "rare enemies"--taking advantage of prey behavior that is usually adaptive for the prey species. Anatomical and physiological analysis showed the tentacles are densely innervated by the trigeminal nerve and are sensitive mechanoreceptors that respond to water movements. Mechanosensory information from the tentacles projects to the optic tectum in approximate register with vision, providing a mechanism for integrating visual and mechanosensory cues for identifying, localizing, and capturing prey. PMID:21534995

  13. Does small-scale vertical distribution of juvenile schooling fish affect prey availability to surface-feeding seabirds in the Wadden Sea?

    NASA Astrophysics Data System (ADS)

    Dänhardt, Andreas; Becker, Peter H.

    2011-02-01

    Food availability is a key variable influencing breeding performance and demography of marine top predators. Due to methodological problems, proportionality between fish abundance and availability is often assumed without being explicitly tested. More specifically, better breeding performance of surface-feeding seabirds at times of large prey stocks suggests that prey availability is also a function of prey abundance. Using vertically resolved stow net sampling we tested whether local abundance and length composition of pelagic fish are reliable predictors of the availability of these fish to surface-feeding Common Terns ( Sterna hirundo) breeding in the German Wadden Sea. Prey fish were found to concentrate below the maximum diving depth of the terns. Individuals caught close to the surface were in most cases smaller than conspecifics caught at greater depth. Correlations between fish abundance within and out of reach of the terns appeared to be both species- and site-specific rather than driven by overall fish abundance. Vertical distribution patterns of the terns' main prey fish could be explained as anti-predator behavior, reducing prey availability to the terns. In 2007, when breeding performance was much better than in 2006, herring and whiting were much more abundant, suggesting that overall prey abundance may also increase prey availability in habitats other than those represented by the stow net sampling.

  14. Examining the relationship between psychosocial and behavioral proxies for future consumption behavior: self-reported impact and bidding behavior in an experimental auction study on cigarette labeling

    PubMed Central

    Rousu, Matthew C.; Thrasher, James F.

    2014-01-01

    Experimental and observational research often involves asking consumers to self-report the impact of some proposed option. Because self-reported responses involve no consequence to the respondent for falsely revealing how he or she feels about an issue, self-reports may be subject to social desirability and other influences that bias responses in important ways. In this article, we analyzed data from an experiment on the impact of cigarette packaging and pack warnings, comparing smokers’ self-reported impact (four-item scale) and the bids they placed in experimental auctions to estimate differences in demand. The results were consistent across methods; however, the estimated effect size associated with different warning labels was two times greater for the four-item self-reported response scale when compared to the change in demand as indicated by auction bids. Our study provides evidence that self-reported psychosocial responses provide a valid proxy for behavioral change as reflected by experimental auction bidding behavior. More research is needed to better understand the advantages and disadvantages of behavioral economic methods and traditional self-report approaches to evaluating health behavior change interventions. PMID:24399267

  15. Prey perception of predation risk: volatile chemical cues mediate non-consumptive effects of a predator on a herbivorous insect.

    PubMed

    Hermann, Sara L; Thaler, Jennifer S

    2014-11-01

    Predators can affect prey in two ways-by reducing their density (consumptive effects) or by changing their behavior, physiology or other phenotypic traits (non-consumptive effects). Understanding the cues and sensory modalities prey use to detect predators is critical for predicting the strength of non-consumptive effects and the outcome of predator-prey encounters. While predator-associated cues have been well studied in aquatic systems, less is known about how terrestrial prey, particularly insect larvae, detect their predators. We evaluated how Colorado potato beetle, Leptinotarsa decemlineata, larvae perceive predation risk by isolating cues from its stink bug predator, the spined soldier bug, Podisus maculiventris. When exposed to male "risk" predators that were surgically manipulated so they could hunt but not kill, beetles reduced feeding 29% compared to controls. Exposure to risk females caused an intermediate response. Beetles ate 24% less on leaves pre-exposed to predators compared to leaves never exposed to predators, indicating that tactile and visual cues are not required for the prey's response. Volatile odor cues from predators reduced beetle feeding by 10% overall, although male predators caused a stronger reduction than females. Finally, visual cues from the predator had a weak effect on beetle feeding. Because multiple cues appear to be involved in prey perception of risk, and because male and female predators have differential effects, beetle larvae likely experience tremendous variation in the information about risk from their local environment. PMID:25234373

  16. Gene Targeting Using Homologous Recombination in Embryonic Stem Cells: The Future for Behavior Genetics?

    PubMed Central

    Gerlai, Robert

    2016-01-01

    Gene targeting with homologous recombination in embryonic stem cells created a revolution in the analysis of the function of genes in behavioral brain research. The technology allowed unprecedented precision with which one could manipulate genes and study the effect of this manipulation on the central nervous system. With gene targeting, the uncertainty inherent in psychopharmacology regarding whether a particular compound would act only through a specific target was removed. Thus, gene targeting became highly popular. However, with this popularity came the realization that like other methods, gene targeting also suffered from some technical and principal problems. For example, two decades ago, issues about compensatory changes and about genetic linkage were raised. Since then, the technology developed, and its utility has been better delineated. This review will discuss the pros and cons of the technique along with these advancements from the perspective of the neuroscientist user. It will also compare and contrast methods that may represent novel alternatives to the homologous recombination based gene targeting approach, including the TALEN and the CRISPR/Cas9 systems. The goal of the review is not to provide detailed recipes, but to attempt to present a short summary of these approaches a behavioral geneticist or neuroscientist may consider for the analysis of brain function and behavior. PMID:27148349

  17. Future health applications of genomics: priorities for communication, behavioral, and social sciences research.

    PubMed

    McBride, Colleen M; Bowen, Deborah; Brody, Lawrence C; Condit, Celeste M; Croyle, Robert T; Gwinn, Marta; Khoury, Muin J; Koehly, Laura M; Korf, Bruce R; Marteau, Theresa M; McLeroy, Kenneth; Patrick, Kevin; Valente, Thomas W

    2010-05-01

    Despite the quickening momentum of genomic discovery, the communication, behavioral, and social sciences research needed for translating this discovery into public health applications has lagged behind. The National Human Genome Research Institute held a 2-day workshop in October 2008 convening an interdisciplinary group of scientists to recommend forward-looking priorities for translational research. This research agenda would be designed to redress the top three risk factors (tobacco use, poor diet, and physical inactivity) that contribute to the four major chronic diseases (heart disease, type 2 diabetes, lung disease, and many cancers) and account for half of all deaths worldwide. Three priority research areas were identified: (1) improving the public's genetic literacy in order to enhance consumer skills; (2) gauging whether genomic information improves risk communication and adoption of healthier behaviors more than current approaches; and (3) exploring whether genomic discovery in concert with emerging technologies can elucidate new behavioral intervention targets. Important crosscutting themes also were identified, including the need to: (1) anticipate directions of genomic discovery; (2) take an agnostic scientific perspective in framing research questions asking whether genomic discovery adds value to other health promotion efforts; and (3) consider multiple levels of influence and systems that contribute to important public health problems. The priorities and themes offer a framework for a variety of stakeholders, including those who develop priorities for research funding, interdisciplinary teams engaged in genomics research, and policymakers grappling with how to use the products born of genomics research to address public health challenges. PMID:20409503

  18. The role of pheromonal responses in rodent behavior: future directions for the development of laboratory protocols.

    PubMed

    Bind, Rebecca H; Minney, Sarah M; Rosenfeld, SaraJane; Hallock, Robert M

    2013-03-01

    Pheromones--chemical signals that can elicit responses in a conspecific--are important in intraspecies communication. Information conveyed by pheromones includes the location of an animal, the presence of food or a threat, sexual attraction, courtship, and dam-pup interactions. These chemical messages remain intact and volatile even when animals, such as rodents, are housed in laboratories rather than their natural environment. Laboratory protocols, such as the cage cleaning and sanitation processes, as well as general housing conditions can alter a rodent's normal production of pheromones in both amount and type and thus may affect behavior. In addition, some procedures induce the release of alarm pheromones that subsequently alter the behavior of other rodents. To prevent pheromonal interference and stress-induced pheromonal release in their research subjects, experimenters should assess current laboratory protocols regarding cage cleaning processes, housing designs, and behavioral assays. Here we discuss how the most commonly used laboratory procedures can alter pheromonal signaling and cause confounding effects. PMID:23562094

  19. Alloparenting experience affects future parental behavior and reproductive success in prairie voles (Microtus ochrogaster).

    PubMed

    Stone, Anita Iyengar; Mathieu, Denise; Griffin, Luana; Bales, Karen Lisa

    2010-01-01

    Various hypotheses have been proposed to explain the function of alloparental behavior in cooperatively breeding species. We examined whether alloparental experience as juveniles enhanced later parental care and reproductive success in the prairie vole (Microtus ochrogaster), a cooperatively breeding rodent. Juveniles cared for one litter of siblings (1EX), two litters of siblings (2EX) or no siblings (0EX). As adults, these individuals were mated to other 0EX, 1EX or 2EX voles, yielding seven different pair combinations, and we recorded measures of parental behaviors, reproductive success, and pup development. As juveniles, individuals caring for siblings for the first time were more alloparental; and as adults, 0EX females paired with 0EX males spent more time in the nest with their pups. Taken together, these results suggest that inexperienced animals spend more time in infant care. As parents, 1EX males spent more time licking their pups than 2EX and 0EX males. Pups with either a 1EX or 2EX parent gained weight faster than pups with 0EX parents during certain developmental periods. While inexperienced animals may spend more time in pup care, long-term benefits of alloparenting may become apparent in the display of certain, particularly important parental behaviors such as licking pups, and in faster weight gain of offspring. PMID:19732810

  20. Clearance rates of ephyrae and small medusae of the common jellyfish Aurelia aurita offered different types of prey

    NASA Astrophysics Data System (ADS)

    Riisgård, Hans Ulrik; Madsen, Caroline V.

    2011-01-01

    Prey selection and knowledge of the amounts of water processed by the early stages of the common jellyfish Aurelia aurita may at certain times of the year be crucial for understanding the plankton dynamics in marine ecosystems with mass occurrences of this jellyfish. In the present study we used two different methods ("clearance method" and "ingestion-rate method") to estimate the amount of water cleared per unit of time of different types and sizes of prey organisms offered to A. aurita ephyrae and small medusae. The mean clearance rates of medusae, estimated with Artemia sp. nauplii as prey by both methods, agreed well, namely 3.8 ± 1.4 l h - 1 by the clearance method and 3.2 ± 1.1 l h - 1 by the ingestion-rate method. Both methods showed that copepods (nauplii and adults) and mussel veligers are captured with considerably lower efficiency, 22 to 37% and 14 to 30%, respectively, than Artemia salina nauplii. By contrast, the water processing rates of ephyrae measured by the clearance method with A. salina nauplii as prey were 3 to 5 times lower than those measured by the ingestion-rate method. This indicates that the prerequisite of full mixing for using the clearance method may not have been fulfilled in the ephyrae experiments. The study demonstrates that the predation impact of the young stages of A. aurita is strongly dependent on its developmental stage (ephyra versus medusa), and the types and sizes of prey organisms. The estimated prey-digestion time of 1.3 h in a steady-state feeding experiment with constant prey concentration supports the reliability of the ingestion-rate method, which eliminates the negative "container effects" of the clearance method, and it seems to be useful in future jellyfish studies, especially on small species/younger stages in which both type and number of prey can be easily and precisely assessed.

  1. Predator-prey interactions mediated by prey personality and predator hunting mode.

    PubMed

    Belgrad, Benjamin A; Griffen, Blaine D

    2016-04-13

    Predator-prey interactions are important drivers in structuring ecological communities. However, despite widespread acknowledgement that individual behaviours and predator species regulate ecological processes, studies have yet to incorporate individual behavioural variations in a multipredator system. We quantified a prevalent predator avoidance behaviour to examine the simultaneous roles of prey personality and predator hunting mode in governing predator-prey interactions. Mud crabs, Panopeus herbstii, reduce their activity levels and increase their refuge use in the presence of predator cues. We measured mud crab mortality and consistent individual variations in the strength of this predator avoidance behaviour in the presence of predatory blue crabs, Callinectes sapidus, and toadfish, Opsanus tau We found that prey personality and predator species significantly interacted to affect mortality with blue crabs primarily consuming bold mud crabs and toadfish preferentially selecting shy crabs. Additionally, the strength of the predator avoidance behaviour depended upon the predation risk from the predator species. Consequently, the personality composition of populations and predator hunting mode may be valuable predictors of both direct and indirect predator-prey interaction strength. These findings support theories postulating mechanisms for maintaining intraspecies diversity and have broad implications for community dynamics. PMID:27075257

  2. Dietary behaviors of adults born prematurely may explain future risk for cardiovascular disease.

    PubMed

    Sharafi, Mastaneh; Duffy, Valerie B; Miller, Robin J; Winchester, Suzy B; Huedo-Medina, Tania B; Sullivan, Mary C

    2016-04-01

    Being born prematurely associates with greater cardiovascular disease (CVD) risk in adulthood. Less understood are the unique and joint associations of dietary patterns and behaviors to this elevated risk among adults who are born prematurely. We aimed to model the associations between term status, dietary and lifestyle behaviors with CVD risk factors while accounting for the longitudinal effects of family protection, and medical or environmental risks. In wave-VIII of a longitudinal study, 23-year olds born prematurely (PT-adults, n = 129) and full term (FT-adults, n = 38) survey-reported liking for foods/beverages and activities, constructed into indexes of dietary quality and sensation-seeking, dietary restraint and physical activity. Measured CVD risk factors included fasting serum lipids and glucose, blood pressure and adiposity. In bivariate relationships, PT-adults reported lower dietary quality (including less affinity for protein-rich foods and higher affinity for sweets), less liking for sensation-seeking foods/activities, and less restrained eating than did FT-adults. In comparison to nationally-representative values and the FT-adults, PT-adults showed greater level of CVD risk factors for blood pressure and serum lipids. In structural equation modeling, dietary quality completely mediated the association between term status and HDL-cholesterol (higher quality, lower HDL-cholesterol) yet joined term status to explain variability in systolic blood pressure (PT-adults with lowest dietary quality had highest blood pressures). Through lower dietary quality, being born prematurely was indirectly linked to higher cholesterol/HDL, higher LDL/HDL and elevated waist/hip ratios. The relationship between dietary quality and CVD risk was strongest for PT-adults who had developed greater cumulative medical risk. Protective environments failed to attenuate relationships between dietary quality and elevated CVD risk among PT-adults. In summary, less healthy dietary

  3. Increased predation of nutrient-enriched aposematic prey.

    PubMed

    Halpin, Christina G; Skelhorn, John; Rowe, Candy

    2014-04-22

    Avian predators readily learn to associate the warning coloration of aposematic prey with the toxic effects of ingesting them, but they do not necessarily exclude aposematic prey from their diets. By eating aposematic prey 'educated' predators are thought to be trading-off the benefits of gaining nutrients with the costs of eating toxins. However, while we know that the toxin content of aposematic prey affects the foraging decisions made by avian predators, the extent to which the nutritional content of toxic prey affects predators' decisions to eat them remains to be tested. Here, we show that European starlings (Sturnus vulgaris) increase their intake of a toxic prey type when the nutritional content is artificially increased, and decrease their intake when nutritional enrichment is ceased. This clearly demonstrates that birds can detect the nutritional content of toxic prey by post-ingestive feedback, and use this information in their foraging decisions, raising new perspectives on the evolution of prey defences. Nutritional differences between individuals could result in equally toxic prey being unequally predated, and might explain why some species undergo ontogenetic shifts in defence strategies. Furthermore, the nutritional value of prey will likely have a significant impact on the evolutionary dynamics of mimicry systems. PMID:24598424

  4. Increased predation of nutrient-enriched aposematic prey

    PubMed Central

    Halpin, Christina G.; Skelhorn, John; Rowe, Candy

    2014-01-01

    Avian predators readily learn to associate the warning coloration of aposematic prey with the toxic effects of ingesting them, but they do not necessarily exclude aposematic prey from their diets. By eating aposematic prey ‘educated’ predators are thought to be trading-off the benefits of gaining nutrients with the costs of eating toxins. However, while we know that the toxin content of aposematic prey affects the foraging decisions made by avian predators, the extent to which the nutritional content of toxic prey affects predators' decisions to eat them remains to be tested. Here, we show that European starlings (Sturnus vulgaris) increase their intake of a toxic prey type when the nutritional content is artificially increased, and decrease their intake when nutritional enrichment is ceased. This clearly demonstrates that birds can detect the nutritional content of toxic prey by post-ingestive feedback, and use this information in their foraging decisions, raising new perspectives on the evolution of prey defences. Nutritional differences between individuals could result in equally toxic prey being unequally predated, and might explain why some species undergo ontogenetic shifts in defence strategies. Furthermore, the nutritional value of prey will likely have a significant impact on the evolutionary dynamics of mimicry systems. PMID:24598424

  5. Plastic hatching timing by red-eyed treefrog embryos interacts with larval predator identity and sublethal predation to affect prey morphology but not performance.

    PubMed

    Touchon, Justin C; Wojdak, Jeremy M

    2014-01-01

    Many animals respond to predation risk by altering their morphology, behavior, or life-history. We know a great deal about the cues prey respond to and the changes to prey that can be induced by predation risk, but less is known about how plastic responses to predators may be affected by separate plastic responses occurring earlier in life, particularly during the embryonic period. Embryos of a broad array of taxa can respond to egg- or larval-stage risks by altering hatching timing, which may alter the way organisms respond to future predators. Using the red-eyed treefrog (Agalychnis callidryas), a model for understanding the effects of plasticity across life-stages, we assessed how the combined effects of induced variation in the timing of embryo hatching and variation in the larval predator community impacted tadpole morphology, pigmentation and swimming performance. We found that A. callidryas tadpoles developed deeper tail muscles and fins and darker pigmentation in response to fish predators, either when alone or in diverse community with other predators. Tadpoles altered morphology much less so to dragonfly naiads or water bugs. Interestingly, morphological responses to predators were also affected by induced differences in hatching age, with early and late-hatched tadpoles exhibiting different allometric relationships between tail height and body length in different predator environments. Beyond induced morphological changes, fish predators often damaged tadpoles' tails without killing them (i.e., sublethal predation), but these tadpoles swam equally quickly to those with fully intact tails. This was due to the fact that tadpoles with more damaged tails increased tail beats to achieve equal swimming speed. This study demonstrates that plastic phenotypic responses to predation risk can be influenced by a complex combination of responses to both the embryo and larval environments, but also that prey performance can be highly resilient to sublethal predation

  6. Plastic Hatching Timing by Red-Eyed Treefrog Embryos Interacts with Larval Predator Identity and Sublethal Predation to Affect Prey Morphology but Not Performance

    PubMed Central

    Touchon, Justin C.; Wojdak, Jeremy M.

    2014-01-01

    Many animals respond to predation risk by altering their morphology, behavior, or life-history. We know a great deal about the cues prey respond to and the changes to prey that can be induced by predation risk, but less is known about how plastic responses to predators may be affected by separate plastic responses occurring earlier in life, particularly during the embryonic period. Embryos of a broad array of taxa can respond to egg- or larval-stage risks by altering hatching timing, which may alter the way organisms respond to future predators. Using the red-eyed treefrog (Agalychnis callidryas), a model for understanding the effects of plasticity across life-stages, we assessed how the combined effects of induced variation in the timing of embryo hatching and variation in the larval predator community impacted tadpole morphology, pigmentation and swimming performance. We found that A. callidryas tadpoles developed deeper tail muscles and fins and darker pigmentation in response to fish predators, either when alone or in diverse community with other predators. Tadpoles altered morphology much less so to dragonfly naiads or water bugs. Interestingly, morphological responses to predators were also affected by induced differences in hatching age, with early and late-hatched tadpoles exhibiting different allometric relationships between tail height and body length in different predator environments. Beyond induced morphological changes, fish predators often damaged tadpoles’ tails without killing them (i.e., sublethal predation), but these tadpoles swam equally quickly to those with fully intact tails. This was due to the fact that tadpoles with more damaged tails increased tail beats to achieve equal swimming speed. This study demonstrates that plastic phenotypic responses to predation risk can be influenced by a complex combination of responses to both the embryo and larval environments, but also that prey performance can be highly resilient to sublethal predation

  7. Neurophysiological basis of rapid eye movement sleep behavior disorder: informing future drug development.

    PubMed

    Jennum, Poul; Christensen, Julie Ae; Zoetmulder, Marielle

    2016-01-01

    Rapid eye movement (REM) sleep behavior disorder (RBD) is a parasomnia characterized by a history of recurrent nocturnal dream enactment behavior and loss of skeletal muscle atonia and increased phasic muscle activity during REM sleep: REM sleep without atonia. RBD and associated comorbidities have recently been identified as one of the most specific and potentially sensitive risk factors for later development of any of the alpha-synucleinopathies: Parkinson's disease, dementia with Lewy bodies, and other atypical parkinsonian syndromes. Several other sleep-related abnormalities have recently been identified in patients with RBD/Parkinson's disease who experience abnormalities in sleep electroencephalographic frequencies, sleep-wake transitions, wake and sleep stability, occurrence and morphology of sleep spindles, and electrooculography measures. These findings suggest a gradual involvement of the brainstem and other structures, which is in line with the gradual involvement known in these disorders. We propose that these findings may help identify biomarkers of individuals at high risk of subsequent conversion to parkinsonism. PMID:27186147

  8. Healthy Variability in Organizational Behavior: Empirical Evidence and New Steps for Future Research.

    PubMed

    Navarro, José; Rueff-Lopes, Rita

    2015-10-01

    The healthy variability thesis suggests that healthy systems function in a complex manner over time. This thesis is well-established in fields like physiology. In the field of organizational behavior, however, this relation is only starting to be explored. The objective of this article is threefold: First, we aim to provide a comprehensive review of the healthy variability thesis including some of the most important findings across different fields, with a focus on evidences from organizational research in work motivation and performance. Second, we discuss an opposite pattern, unhealthy stability, i.e., the relationship between unhealthy behaviors and lower variability. Again, we provide evidence from diverse areas, from affective processes to disruptive organizational comportments like mobbing. Third, we provide a critical evaluation of current methodological trends and highlight what we believe to be the main factors that are stopping organizational research from advancing in the field. Theoretical, methodological and epistemological implications are discussed. To conclude, we draw a compilation of the lessons learned, which hopefully provide insights for prolific research avenues. Our main purpose is to raise awareness of the healthy variability thesis and to enthuse organizational researchers to consider it in order to advance existing knowledge, revisit old theories and create new ones. PMID:26375939

  9. Neurophysiological basis of rapid eye movement sleep behavior disorder: informing future drug development

    PubMed Central

    Jennum, Poul; Christensen, Julie AE; Zoetmulder, Marielle

    2016-01-01

    Rapid eye movement (REM) sleep behavior disorder (RBD) is a parasomnia characterized by a history of recurrent nocturnal dream enactment behavior and loss of skeletal muscle atonia and increased phasic muscle activity during REM sleep: REM sleep without atonia. RBD and associated comorbidities have recently been identified as one of the most specific and potentially sensitive risk factors for later development of any of the alpha-synucleinopathies: Parkinson’s disease, dementia with Lewy bodies, and other atypical parkinsonian syndromes. Several other sleep-related abnormalities have recently been identified in patients with RBD/Parkinson’s disease who experience abnormalities in sleep electroencephalographic frequencies, sleep–wake transitions, wake and sleep stability, occurrence and morphology of sleep spindles, and electrooculography measures. These findings suggest a gradual involvement of the brainstem and other structures, which is in line with the gradual involvement known in these disorders. We propose that these findings may help identify biomarkers of individuals at high risk of subsequent conversion to parkinsonism. PMID:27186147

  10. A Rao-Blackwellized particle filter for joint parameter estimation and biomass tracking in a stochastic predator-prey system.

    PubMed

    Martín-Fernández, Laura; Gilioli, Gianni; Lanzarone, Ettore; Miguez, Joaquin; Pasquali, Sara; Ruggeri, Fabrizio; Ruiz, Diego P

    2014-06-01

    Functional response estimation and population tracking in predator-prey systems are critical problems in ecology. In this paper we consider a stochastic predator-prey system with a Lotka-Volterra functional response and propose a particle filtering method for: (a) estimating the behavioral parameter representing the rate of effective search per predator in the functional response and (b) forecasting the population biomass using field data. In particular, the proposed technique combines a sequential Monte Carlo sampling scheme for tracking the time-varying biomass with the analytical integration of the unknown behavioral parameter. In order to assess the performance of the method, we show results for both synthetic and observed data collected in an acarine predator-prey system, namely the pest mite Tetranychus urticae and the predatory mite Phytoseiulus persimilis. PMID:24506552

  11. Development of an evolutionary fuzzy expert system for estimating future behavior of stock price

    NASA Astrophysics Data System (ADS)

    Mehmanpazir, Farhad; Asadi, Shahrokh

    2016-07-01

    The stock market has always been an attractive area for researchers since no method has been found yet to predict the stock price behavior precisely. Due to its high rate of uncertainty and volatility, it carries a higher risk than any other investment area, thus the stock price behavior is difficult to simulation. This paper presents a "data mining-based evolutionary fuzzy expert system" (DEFES) approach to estimate the behavior of stock price. This tool is developed in seven-stage architecture. Data mining is used in three stages to reduce the complexity of the whole data space. The first stage, noise filtering, is used to make our raw data clean and smooth. Variable selection is second stage; we use stepwise regression analysis to choose the key variables been considered in the model. In the third stage, K-means is used to divide the data into sub-populations to decrease the effects of noise and rebate complexity of the patterns. At next stage, extraction of Mamdani type fuzzy rule-based system will be carried out for each cluster by means of genetic algorithm and evolutionary strategy. In the fifth stage, we use binary genetic algorithm to rule filtering to remove the redundant rules in order to solve over learning phenomenon. In the sixth stage, we utilize the genetic tuning process to slightly adjust the shape of the membership functions. Last stage is the testing performance of tool and adjusts parameters. This is the first study on using an approximate fuzzy rule base system and evolutionary strategy with the ability of extracting the whole knowledge base of fuzzy expert system for stock price forecasting problems. The superiority and applicability of DEFES are shown for International Business Machines Corporation and compared the outcome with the results of the other methods. Results with MAPE metric and Wilcoxon signed ranks test indicate that DEFES provides more accuracy and outperforms all previous methods, so it can be considered as a superior tool for

  12. Changing Health Behaviors to Improve Health Outcomes after Angioplasty: A Randomized Trial of Net Present Value versus Future Value Risk Communication

    ERIC Educational Resources Information Center

    Charlson, M. E.; Peterson, J. C.; Boutin-Foster, C.; Briggs, W. M.; Ogedegbe, G. G.; McCulloch, C. E.; Hollenberg, J.; Wong, C.; Allegrante, J. P.

    2008-01-01

    Patients who have undergone angioplasty experience difficulty modifying at-risk behaviors for subsequent cardiac events. The purpose of this study was to test whether an innovative approach to framing of risk, based on "net present value" economic theory, would be more effective in behavioral intervention than the standard "future value approach"…

  13. Behavioral Interventions and Cardiovascular Risk in Obese Youth: Current Findings and Future Directions

    PubMed Central

    Vannucci, Anna; Wilfley, Denise E.

    2012-01-01

    The identification and early intervention of pediatric obesity is critical to reducing cardiovascular disease (CVD). Family-based behavioral interventions have consistently demonstrated efficacy in reducing adiposity and CVD risk factors (i.e., blood pressure, cholesterol, fasting glucose levels, insulin resistance, metabolic syndrome). Even modest weight loss in severely obese youth can lead to sustained improvement in CVD risk factors. However, weight regain following treatment cessation remains a challenge in the contemporary obesogenic environment. Intensive family-based interventions spanning socioenvironmental contexts (i.e., home, peer, community) show promise in sustaining weight loss in the long-term. Despite having effective treatments for pediatric obesity and CVD risk factors, families rarely have access to these programs and so increasing the role of healthcare providers in screening and referral efforts is imperative. Moving forward, it is also essential to establish communication and cooperative networks across sectors build sustainable prevention and intervention programs and to provide cohesive health messages. PMID:23336013

  14. SOHO hunts elusive solar prey

    NASA Astrophysics Data System (ADS)

    1995-10-01

    , shorter oscillations refer to shallower layers. By considering a sequence of oscillations with longer and longer periods, describing sound waves that penetrate deeper and deeper, SOHO will 'peel away' progressively distant layers of the Sun and establish physical properties inside the Sun's deep interior. Since the technique is similar in scientific principle to using earthquakes, or seismic waves, to decipher the Earth's internal structure, it has become known as helioseismology. SOHO's helioseismology data may shed light on solar neutrinos; they are insubstantial, subatomic particles created in prodigious quantities inside the Sun's energy-generating core. Neutrinos move at the velocity of light and travel almost unimpeded through the Sun, the Earth and nearly any amount of matter. The difficulty is that underground detectors always observe fewer neutrinos than theory says they should detect, a discrepancy known as the solar neutrino problem. Either the Sun does not shine the way we think it ought to, or our basic understanding of neutrinos is in error. SOHO's record of surface oscillations may establish the temperature at the centre of the Sun, and tell us if there is something wrong with our knowledge of the way stars shine. If the centre of the Sun is about a million degrees cooler than is presently thought, nuclear reactions would produce fewer neutrinos and resolve the solar neutrino problem. But if the internal temperature has the expected value, then the neutrinos may have an identity crisis, undergoing metamorphosis before reaching terrestrial detectors that therefore cannot see them. Future SOHO helioseismology observations will also improve our understanding of the solar dynamo responsible for the Sun's magnetic field. The dynamo is located somewhere in the solar interior where the hot, rotating material generates electrical currents and converts the energy of motion into magnetic energy. Magnetic fields, spawned by the dynamo inside the Sun, thread their way

  15. Dynamics of the echolocation beam during prey pursuit in aerial hawking bats.

    PubMed

    Jakobsen, Lasse; Olsen, Mads Nedergaard; Surlykke, Annemarie

    2015-06-30

    In the evolutionary arms race between prey and predator, measures and countermeasures continuously evolve to increase survival on both sides. Bats and moths are prime examples. When exposed to intense ultrasound, eared moths perform dramatic escape behaviors. Vespertilionid and rhinolophid bats broaden their echolocation beam in the final stage of pursuit, presumably as a countermeasure to keep evading moths within their "acoustic field of view." In this study, we investigated if dynamic beam broadening is a general property of echolocation when catching moving prey. We recorded three species of emballonurid bats, Saccopteryx bilineata, Saccopteryx leptura, and Rhynchonycteris naso, catching airborne insects in the field. The study shows that S. bilineata and S. leptura maintain a constant beam shape during the entire prey pursuit, whereas R. naso broadens the beam by lowering the peak call frequency from 100 kHz during search and approach to 67 kHz in the buzz. Surprisingly, both Saccopteryx bats emit calls with very high energy throughout the pursuit, up to 60 times more than R. naso and Myotis daubentonii (a similar sized vespertilionid), providing them with as much, or more, peripheral "vision" than the vespertilionids, but ensonifying objects far ahead suggesting more clutter. Thus, beam broadening is not a fundamental property of the echolocation system. However, based on the results, we hypothesize that increased peripheral detection is crucial to all aerial hawking bats in the final stages of prey pursuit and speculate that beam broadening is a feature characterizing more advanced echolocation. PMID:26080398

  16. Oxytocin tempers calculated greed but not impulsive defense in predator–prey contests

    PubMed Central

    Scholte, H. Steven; van Winden, Frans A. A. M.; Ridderinkhof, K. Richard

    2015-01-01

    Human cooperation and competition is modulated by oxytocin, a hypothalamic neuropeptide that functions as both hormone and neurotransmitter. Oxytocin’s functions can be captured in two explanatory yet largely contradictory frameworks: the fear-dampening (FD) hypothesis that oxytocin has anxiolytic effects and reduces fear-motivated action; and the social approach/avoidance (SAA) hypothesis that oxytocin increases cooperative approach and facilitates protection against aversive stimuli and threat. We tested derivations from both frameworks in a novel predator–prey contest game. Healthy males given oxytocin or placebo invested as predator to win their prey’s endowment, or as prey to protect their endowment against predation. Neural activity was registered using 3T-MRI. In prey, (fear-motivated) investments were fast and conditioned on the amygdala. Inconsistent with FD, oxytocin did not modulate neural and behavioral responding in prey. In predators, (greed-motivated) investments were slower, and conditioned on the superior frontal gyrus (SFG). Consistent with SAA, oxytocin reduced predator investment, time to decide and activation in SFG. Thus, whereas oxytocin does not incapacitate the impulsive ability to protect and defend oneself, it lowers the greedy and more calculated appetite for coming out ahead. PMID:25140047

  17. The biomechanics of fast prey capture in aquatic bladderworts

    PubMed Central

    Singh, Amit K.; Prabhakar, Sunil; Sane, Sanjay P.

    2011-01-01

    Carnivorous plants match their animal prey for speed of movements and hence offer fascinating insights into the evolution of fast movements in plants. Here, we describe the mechanics of prey capture in aquatic bladderworts Utricularia stellaris, which prey on swimming insect larvae or nematodes to supplement their nitrogen intake. The closed Utricularia bladder develops lower-than-ambient internal pressures by pumping out water from the bladder and thus setting up an elastic instability in bladder walls. When the external sensory trigger hairs on their trapdoor are mechanically stimulated by moving prey, the trapdoor opens within 300–700 μs, causing strong inward flows that trap their prey. The opening time of the bladder trapdoor is faster than any recorded motion in carnivorous plants. Thus, Utricularia have evolved a unique biomechanical system to gain an advantage over their animal prey. PMID:21389013

  18. Health-related quality of life among veterans in addictions treatment: identifying behavioral targets for future intervention

    PubMed Central

    Oppezzo, Marily A.; Michalek, Anne K.; Delucchi, Kevin; Baiocchi, Michael T. M.; Barnett, Paul G.

    2016-01-01

    Background US veterans report lower health-related quality of life (HRQoL) relative to the general population. Identifying behavioral factors related to HRQoL that are malleable to change may inform interventions to improve well-being in this vulnerable group. Purpose The current study sought to characterize HRQoL in a largely male sample of veterans in addictions treatment, both in relation to US norms and in association with five recommended health behavior practices: regularly exercising, managing stress, having good sleep hygiene, consuming fruits and vegetables, and being tobacco free. Methods We assessed HRQoL with 250 veterans in addictions treatment (96 % male, mean age 53, range 24–77) using scales from four validated measures. Data reduction methods identified two principal components reflecting physical and mental HRQoL. Model testing of HRQoL associations with health behaviors adjusted for relevant demographic and treatment-related covariates. Results Compared to US norms, the sample had lower HRQoL scores. Better psychological HRQoL was associated with higher subjective social standing, absence of pain or trauma, lower alcohol severity, and monotonically with the sum of health behaviors (all p < 0.05). Specifically, psychological HRQoL was associated with regular exercise, stress management, and sleep hygiene. Regular exercise also related to better physical HRQoL. The models explained >40 % of the variance in HRQoL. Conclusions Exercise, sleep hygiene, and stress management are strongly associated with HRQoL among veterans in addictions treatment. Future research is needed to test the effect of interventions for improving well-being in this high-risk group. PMID:26886926

  19. Cognitive-Behavioral Therapy for Youth with Body Dysmorphic Disorder: Current Status and Future Directions

    PubMed Central

    Phillips, Katharine A.; Rogers, Jamison

    2011-01-01

    SYNOPSIS Body dysmorphic disorder (BDD), a distressing or impairing preoccupation with nonexistent or slight defect(s) in appearance, usually begins during early adolescence and appears to be common in youth. BDD is characterized by substantial impairment in psychosocial functioning and markedly high rates of suicidality. Cognitive-behavioral therapy (CBT) tailored to BDD’s unique features is the best tested and most promising psychosocial treatment for adults with BDD. CBT has been used for youth with BDD, but it has not been systematically developed for or tested in this age group, and there is a pressing need for this work to be done. This article focuses on CBT for BDD in adults and youth, possible adaptations for youth, and the need for treatment research in youth. We also discuss BDD’s prevalence, clinical features, how to diagnose BDD in youth, recommended pharmacotherapy for BDD (serotonin-reuptake inhibitors), and treatments that are not recommended (surgery and other cosmetic treatments). PMID:21440856

  20. Nash Equilibria in Noncooperative Predator-Prey Games

    SciTech Connect

    Ramos, Angel Manuel Roubicek, Tomas

    2007-09-15

    A noncooperative game governed by a distributed-parameter predator-prey system is considered, assuming that two players control initial conditions for predator and prey, respectively. Existence of a Nash equilibrium is shown under the condition that the desired population profiles and the environmental carrying capacity for the prey are sufficiently small. A conceptual approximation algorithm is proposed and analyzed. Finally, numerical simulations are performed, too.

  1. Prey selectivity affects reproductive success of a corallivorous reef fish.

    PubMed

    Brooker, Rohan M; Jones, Geoffrey P; Munday, Philip L

    2013-06-01

    Most animals consume a narrower range of food resources than is potentially available in the environment, but the underlying basis for these preferences is often poorly understood. Foraging theory predicts that prey selection should represent a trade-off between prey preferences based on nutritional value and prey availability. That is, species should consume preferred prey when available, but select less preferred prey when preferred prey is rare. We employed both field observation and laboratory experiments to examine the relationship between prey selection and preferences in the obligate coral-feeding filefish, Oxymonacanthus longirostris. To determine the drivers of prey selection, we experimentally established prey preferences in choice arenas and tested the consequences of prey preferences for key fitness-related parameters. Field studies showed that individuals fed almost exclusively on live corals from the genus Acropora. While diet was dominated by the most abundant species, Acropora nobilis, fish appeared to preferentially select rarer acroporids, such as A. millepora and A. hyacinthus. Prey choice experiments confirmed strong preferences for these corals, suggesting that field consumption is constrained by availability. In a longer-term feeding experiment, reproductive pairs fed on non-preferred corals exhibited dramatic reductions to body weight, and in hepatic and gonad condition, compared with those fed preferred corals. The majority of pairs fed preferred corals spawned frequently, while no spawning was observed for any pairs fed a non-preferred species of coral. These experiments suggest that fish distinguish between available corals based on their intrinsic value as prey, that reproductive success is dependent on the presence of particular coral species, and that differential loss of preferred corals could have serious consequences for the population success of these dietary specialists. PMID:23124333

  2. An investigation into the chemical composition of alternative invertebrate prey.

    PubMed

    Oonincx, D G A B; Dierenfeld, E S

    2012-01-01

    The aim of this study was to determine the chemical composition of eight invertebrate species and evaluate their suitability as alternative prey. The species selected were rusty red cockroaches (Blatta lateralis), six-spotted cockroaches (Eublaberus distanti), Madagascar hissing cockroaches (Gromphadorhina portentosa), fruit flies (Drosophila melanogaster), false katydids (Microcentrum rhombifolium), beetles of the mealworm (Tenebrio molitor), and superworm beetles (Zophobas morio), as well as woodlice (Porcellio scaber). Dry matter (DM), crude protein, crude fat, neutral detergent fiber, acid detergent fiber, ash, macro and trace minerals, vitamins A and E, and carotenoid concentrations were quantified. Significant differences were found between species. Crude protein content ranged from 38 to 76% DM, fat from14 to 54% DM, and ash from 2 to 8% DM. In most species, calcium:phosphorus was low (0.08-0.30:1); however, P. scaber was an exception (12:1) and might prove useful as a dietary source of calcium for insectivores. Vitamin E content was low for most species (6-16 mg/kg DM), except for D. melanogaster and M. rhombifolium (112 and 110 mg/kg DM). The retinol content, as a measure of vitamin A activity, was low in all specimens, but varied greatly among samples (0.670-886 mg/kg DM). The data presented can be used to alter diets to better suit the estimated requirements of insectivores in captivity. Future research on the topic of composition of invertebrate prey species should focus on determination of nutrient differences owing to species, developmental stage, and diet. PMID:21442652

  3. Molecular prey identification in Central European piscivores.

    PubMed

    Thalinger, Bettina; Oehm, Johannes; Mayr, Hannes; Obwexer, Armin; Zeisler, Christiane; Traugott, Michael

    2016-01-01

    Diet analysis is an important aspect when investigating the ecology of fish-eating animals and essential for assessing their functional role in food webs across aquatic and terrestrial ecosystems. The identification of fish remains in dietary samples, however, can be time-consuming and unsatisfying using conventional morphological analysis of prey remains. Here, we present a two-step multiplex PCR system, comprised of six assays, allowing for rapid, sensitive and specific detection of fish DNA in dietary samples. This approach encompasses 78 fish and lamprey species native to Central European freshwaters and enables the identification of 31 species, six genera, two families, two orders and two fish family clusters. All targeted taxa were successfully amplified from 25 template molecules, and each assay was specific when tested against a wide range of invertebrates and vertebrates inhabiting aquatic environments. The applicability of the multiplex PCR system was evaluated in a feeding trial, wherein it outperformed morphological prey analysis regarding species-specific prey identification in faeces of Eurasian otters. Additionally, a wide spectrum of fish species was detected in field-collected faecal samples and regurgitated pellets of Common Kingfishers and Great Cormorants, demonstrating the broad applicability of the approach. In conclusion, this multiplex PCR system provides an efficient, easy to use and cost-effective tool for assessing the trophic ecology of piscivores in Central Europe. Furthermore, the multiplex PCRs and the primers described therein will be applicable wherever DNA of the targeted fish species needs to be detected at high sensitivity and specificity. PMID:26053612

  4. Prey processing in the Siamese fighting fish (Betta splendens).

    PubMed

    Konow, Nicolai; Krijestorac, Belma; Sanford, Christopher P J; Boistel, Renauld; Herrel, Anthony

    2013-07-01

    We studied prey processing in the Siamese fighting fish (Betta splendens), involving slow, easily observed head-bobbing movements, which were compared with prey processing in other aquatic feeding vertebrates. We hypothesized that head-bobbing is a unique prey-processing behaviour, which alternatively could be structurally and functionally analogous with raking in basal teleosts, or with pharyngognathy in neoteleosts. Modulation of head-bobbing was elicited by prey with different motility and toughness. Head-bobbing involved sustained mouth occlusion and pronounced cranial elevation, similar to raking. However, the hyoid and pectoral girdle were protracted, and not retracted as in both raking and pharyngognathy. High-speed videofluoroscopy of hyoid movements confirmed that head-bobbing differs from other known aquatic prey-processing behaviours. Nevertheless, head-bobbing and other prey-processing behaviours converge on a recurrent functional theme in the trophic ecology of aquatic feeding vertebrates; the use of intraoral and oropharyngeal dentition surfaces to immobilize, reduce and process relatively large, tough or motile prey. Prey processing outside the pharyngeal region has not been described for neoteleosts previously, but morphological evidence suggests that relatives of Betta might use similar processing behaviours. Thus, our results suggest that pharyngognathy did not out-compete ancestral prey-processing mechanisms completely during the evolution of neoteleosts. PMID:23612845

  5. Alternative prey use affects helminth parasite infections in grey wolves.

    PubMed

    Friesen, Olwyn C; Roth, James D

    2016-09-01

    Predators affect prey populations not only through direct predation, but also by acting as definitive hosts for their parasites and completing parasite life cycles. Understanding the affects of parasitism on prey population dynamics requires knowing how their predators' parasite community is affected by diet and prey availability. Ungulates, such as moose (Alces americanus) and white-tailed deer (Odocoileus virginianus), are often important prey for wolves (Canis lupus), but wolves also consume a variety of alternative prey, including beaver (Castor canadensis) and snowshoe hare (Lepus americanus). The use of alternative prey, which may host different or fewer parasites than ungulates, could potentially reduce overall abundance of ungulate parasites within the ecosystem, benefiting both wolves and ungulate hosts. We examined parasites in wolf carcasses from eastern Manitoba and estimated wolf diet using stable isotope analysis. Taeniidae cestodes were present in most wolves (75%), reflecting a diet primarily comprised of ungulates, but nematodes were unexpectedly rare. Cestode abundance was negatively related to the wolf's δ(13) C value, indicating diet affects parasite abundance. Wolves that consumed a higher proportion of beaver and caribou (Rangifer tarandus), estimated using Bayesian mixing models, had lower cestode abundance, suggesting the use of these alternative prey can reduce parasite loads. Long-term consumption of beavers may lower the abundance of adult parasites in wolves, eventually lowering parasite density in the region and ultimately benefiting ungulates that serve as intermediate hosts. Thus, alternative prey can affect both predator-prey and host-parasite interactions and potentially affect food web dynamics. PMID:27155132

  6. Assassin bug uses aggressive mimicry to lure spider prey.

    PubMed

    Wignall, Anne E; Taylor, Phillip W

    2011-05-01

    Assassin bugs (Stenolemus bituberus) hunt web-building spiders by invading the web and plucking the silk to generate vibrations that lure the resident spider into striking range. To test whether vibrations generated by bugs aggressively mimic the vibrations generated by insect prey, we compared the responses of spiders to bugs with how they responded to prey, courting male spiders and leaves falling into the web. We also analysed the associated vibrations. Similar spider orientation and approach behaviours were observed in response to vibrations from bugs and prey, whereas different behaviours were observed in response to vibrations from male spiders and leaves. Peak frequency and duration of vibrations generated by bugs were similar to those generated by prey and courting males. Further, vibrations from bugs had a temporal structure and amplitude that were similar to vibrations generated by leg and body movements of prey and distinctly different to vibrations from courting males or leaves, or prey beating their wings. To be an effective predator, bugs do not need to mimic the full range of prey vibrations. Instead bugs are general mimics of a subset of prey vibrations that fall within the range of vibrations classified by spiders as 'prey'. PMID:20980305

  7. Aquatic prey capture in ray-finned fishes: a century of progress and new directions.

    PubMed

    Ferry-Graham, L A; Lauder, G V

    2001-05-01

    The head of ray-finned fishes is structurally complex and is composed of numerous bony, muscular, and ligamentous elements capable of intricate movement. Nearly two centuries of research have been devoted to understanding the function of this cranial musculoskeletal system during prey capture in the dense and viscous aquatic medium. Most fishes generate some amount of inertial suction to capture prey in water. In this overview we trace the history of functional morphological analyses of suction feeding in ray-finned fishes, with a particular focus on the mechanisms by which suction is generated, and present new data using a novel flow imaging technique that enables quantification of the water flow field into the mouth. We begin with a brief overview of studies of cranial anatomy and then summarize progress on understanding function as new information was brought to light by the application of various forms of technology, including high-speed cinematography and video, pressure, impedance, and bone strain measurement. We also provide data from a new technique, digital particle image velocimetry (DPIV) that allows us to quantify patterns of flow into the mouth. We believe that there are three general areas in which future progress needs to occur. First, quantitative three-dimensional studies of buccal and opercular cavity dimensions during prey capture are needed; sonomicrometry and endoscopy are techniques likely to yield these data. Second, a thorough quantitative analysis of the flow field into the mouth during prey capture is necessary to understand the effect of head movement on water in the vicinity of the prey; three-dimensional DPIV analyses will help to provide these data. Third, a more precise understanding of the fitness effects of structural and functional variables in the head coupled with rigorous statistical analyses will allow us to better understand the evolutionary consequences of intra- and interspecific variation in cranial morphology and function

  8. Fussy feeders: phyllosoma larvae of the Western Rocklobster (Panulirus cygnus) demonstrate prey preference.

    PubMed

    Saunders, Megan I; Thompson, Peter A; Jeffs, Andrew G; Säwström, Christin; Sachlikidis, Nikolas; Beckley, Lynnath E; Waite, Anya M

    2012-01-01

    The Western Rocklobster (Panulirus cygnus) is the most valuable single species fishery in Australia and the largest single country spiny lobster fishery in the world. In recent years a well-known relationship between oceanographic conditions and lobster recruitment has become uncoupled, with significantly lower recruitment than expected, generating interest in the factors influencing survival and development of the planktonic larval stages. The nutritional requirements and wild prey of the planktotrophic larval stage (phyllosoma) of P. cygnus were previously unknown, hampering both management and aquaculture efforts for this species. Ship-board feeding trials of wild-caught mid-late stage P. cygnus phyllosoma in the eastern Indian Ocean, off the coast of Western Australia, were conducted in July 2010 and August-September 2011. In a series of experiments, phyllosoma were fed single and mixed species diets of relatively abundant potential prey items (chaetognaths, salps, and krill). Chaetognaths were consumed in 2-8 times higher numbers than the other prey, and the rate of consumption of chaetognaths increased with increasing concentration of prey. The highly variable lipid content of the phyllosoma, and the fatty acid profiles of the phyllosoma and chaetognaths, indicated they were from an oligotrophic oceanic food chain where food resources for macrozooplankton were likely to be constrained. Phyllosoma fed chaetognaths over 6 days showed significant changes in some fatty acids and tended to accumulate lipid, indicating an improvement in overall nutritional condition. The discovery of a preferred prey for P. cygnus will provide a basis for future oceanographic, management and aquaculture research for this economically and ecologically valuable species. PMID:22586479

  9. Global existence of solutions and uniform persistence of a diffusive predator-prey model with prey-taxis

    NASA Astrophysics Data System (ADS)

    Wu, Sainan; Shi, Junping; Wu, Boying

    2016-04-01

    This paper proves the global existence and boundedness of solutions to a general reaction-diffusion predator-prey system with prey-taxis defined on a smooth bounded domain with no-flux boundary condition. The result holds for domains in arbitrary spatial dimension and small prey-taxis sensitivity coefficient. This paper also proves the existence of a global attractor and the uniform persistence of the system under some additional conditions. Applications to models from ecology and chemotaxis are discussed.

  10. Do Predators Always Win? Starfish versus Limpets: A Hands-On Activity Examining Predator-Prey Interactions

    ERIC Educational Resources Information Center

    Faria, Claudia; Boaventura, Diana; Galvao, Cecilia; Chagas, Isabel

    2011-01-01

    In this article we propose a hands-on experimental activity about predator-prey interactions that can be performed both in a research laboratory and in the classroom. The activity, which engages students in a real scientific experiment, can be explored not only to improve students' understanding about the diversity of anti-predator behaviors but…

  11. Predator odor recognition and antipredatory response in fish: does the prey know the predator diel rhythm?

    NASA Astrophysics Data System (ADS)

    Ylönen, Hannu; Kortet, Raine; Myntti, Janne; Vainikka, Anssi

    2007-01-01

    We studied in a laboratory experiment using stream tanks if two percid prey fish, the perch ( Perca fluviatilis) and the ruffe ( Gymnocephalus cernuus), can recognize and respond to increased predation risk using odors of two piscivores, the pike ( Esox lucius) and the burbot ( Lota lota). Burbot is night-active most of the year but pike hunts predominantly visually whenever there is enough light. Perch is a common day-active prey of pike and dark-active ruffe that of burbot. We predicted that besides recognizing the predator odors, the prey species would respond more strongly to odors of the predator which share the same activity pattern. Both perch and ruffe clearly responded to both predator fish odors. They decreased movements and erected the spiny dorsal fins. Fin erection showed clearly the black warning ornamentation in the fin and thus erected fin may function besides as mechanical defense also as warning ornament for an approaching predator. No rapid escape movements were generally observed. Both perch and ruffe responded more strongly to pike odor than to burbot. There were no clear differences in response between day and night. In conclusion, we were able to verify clear predator odor recognition by both prey fish. Both perch and ruffe responded to both predator odors and it seemed that pike forms a stronger threat for both prey species. Despite of diel activity differences both perch and ruffe used the same antipredatory strategies, but the day-active perch seemed to have a more flexible antipredatory behavior by responding more strongly to burbot threat during the night when burbot is active.

  12. Behavioral Health and Performance at NASA JSC: Recent Successes and Future Plan for BHP Research and Operations

    NASA Technical Reports Server (NTRS)

    Leveton, L. B.; VanderArk, S. T.

    2014-01-01

    The Behavioral Health and Performance discipline at NASA Johnson Space Center is organized into two distinct Divisions (Biomedical Research and Environmental Science Division and Space and Clinical Operations Division) but is integrated and interrelated in its day-to-day work. Ongoing operations supporting NASA's spaceflight goals benefit from the research portfolios that address risks to mission success. Similarly, these research portfolios are informed by operations to ensure investigations stay relevant given the dynamic environment of spaceflight. There are many success stories that can be presented where initial work begun as a BHP Research project, and funded through the Human Research Program, was fully implemented in operations or addressed an operational need. Examples include improving effectiveness of the debriefings used within Mission Control by the Mission Operations Directorate and countermeasures for fatigue management. There is also ongoing collaboration with research and operations for developing selection methods for future generation astronauts, and to enhance and inform the current family support function. The objective of this panel is to provide examples of recent success stories, describe areas where close collaboration is benefitting ongoing research and operations, and summarize how this will come together as NASA plans for the one year ISS mission - a unique opportunity for both BHP operations and research to learn more about preparing and supporting crewmembers for extended missions in space. The proposed panel will be comprised of six presentations, each describing a unique aspect of research or operations and the benefits to current and future spaceflight.

  13. Variation in prey selection of a piscivorous fish after the impoundment of a neotropical reservoir: prey size and type.

    PubMed

    Cantanhêde, G; Fugi, R; Hahn, N S

    2009-07-01

    The relative abundance and size of prey fish in the stomachs of the predator Acestrorhynchus pantaneiro were compared with those recorded in the field to estimate prey selection. Fish samples were taken monthly in the Manso Reservoir (State of Mato Grosso, Brazil) immediately after the impoundment, from March 2000 to February 2001 (period I) and from March 2003 to February 2004 (period II). In period I, the small relative dominance of the prey in the environment seemed to have lead to random foraging. In period II, however, when the forage fish Moenkhausia dichroura was dominant in the environment, the predator shifted its diet, foraging mainly on this prey. Species with short relative body depth were positively selected. The prey size classes between 30 and 49 mm, and 50 and 69 mm standard length (L(S)) were the most abundant in the environment. Small prey were predominantly selected by A. pantaneiro. Even when a given prey or prey size was predominant in the environment, A. pantaneiro was a selective predator and maintained its preferences associated to prey type and L(S), although it consumed the most abundant resource. PMID:20738483

  14. Temporal and spatial trends in prey composition of wahoo Acanthocybium solandri: a diet analysis from the central North Pacific Ocean using visual and DNA bar-coding techniques.

    PubMed

    Oyafuso, Z S; Toonen, R J; Franklin, E C

    2016-04-01

    A diet analysis was conducted on 444 wahoo Acanthocybium solandri caught in the central North Pacific Ocean longline fishery and a nearshore troll fishery surrounding the Hawaiian Islands from June to December 2014. In addition to traditional observational methods of stomach contents, a DNA bar-coding approach was integrated into the analysis by sequencing the cytochrome c oxidase subunit 1 (COI) region of the mtDNA genome to taxonomically identify individual prey items that could not be classified visually to species. For nearshore-caught A. solandri, juvenile pre-settlement reef fish species from various families dominated the prey composition during the summer months, followed primarily by Carangidae in autumn months. Gempylidae, Echeneidae and Scombridae were dominant prey taxa from the offshore fishery. Molidae was a common prey family found in stomachs collected north-east of the Hawaiian Archipelago while tetraodontiform reef fishes, known to have extended pelagic stages, were prominent prey items south-west of the Hawaiian Islands. The diet composition of A. solandri was indicative of an adaptive feeder and thus revealed dominant geographic and seasonal abundances of certain taxa from various ecosystems in the marine environment. The addition of molecular bar-coding to the traditional visual method of prey identifications allowed for a more comprehensive range of the prey field of A. solandri to be identified and should be used as a standard component in future diet studies. PMID:27059148

  15. Bats as the main prey of wintering long-eared owl (Asio otus) in Beijing: Integrating biodiversity protection and urban management.

    PubMed

    Tian, Long; Zhou, Xuwei; Shi, Yang; Guo, Yumin; Bao, Weidong

    2015-03-01

    The loss of biodiversity from urbanized areas is a major environmental problem challenging policy-makers throughout the world. Solutions to this problem are urgently required in China. We carried out a case study of wintering long-eared owls (Asio otus) and their main prey to illustrate the negative effects of urbanization combined with ineffective conservation of biodiversity in Beijing. Field monitoring of owl numbers at two roosting sites from 2004 to 2012 showed that the owl population had fallen rapidly in metropolitan Beijing. Analysis of pellet contents identified only seven individuals of two species of shrew. The majority of mammalian prey comprised four bat and seven rodent species, making up 29.3% and 29.5% of the prey items, respectively. Prey composition varied significantly among years at the two sample sites. At the urban site the consumption of bats and rodents declined gradually over time, while predation on birds increased. In contrast, at the suburban site the prey composition showed an overall decrease in the number of bats, a sharp increase and a subsequent decrease in bird prey, and the number of rodent prey fell to a low point. Rapid development of real estate and inadequate greenfield management in city parks resulted in negative effects on the bird and small mammal habitat of urban areas in Beijing. We suggest that measures to conserve biodiversity should be integrated into future urban planning to maintain China's rich biodiversity while also achieving sustainable economic development. PMID:25316405

  16. Ancient fish and recent invaders: white sturgeon Acipenser transmontanus diet response to invasive-species-mediated changes in a benthic prey assemblage

    USGS Publications Warehouse

    Zeug, Steven C; Brodsky, Annie; Kogut, Nina; Stewart, Robin; Merz, Joe

    2014-01-01

    Invasive organisms can have significant impacts on native species, and the San Francisco Estuary (SFE), California, USA, is one of the world's most invaded estuaries. Decline of native white sturgeon Acipenser transmontanus abundance in the SFE has been acknowledged, but underlying mechanisms are poorly understood. Invasion by the overbite clam Potamocorbula amurensis has drastically altered the SFE benthic prey community, yet little is known about how this change has affected sturgeon diets. We investigated changes in the diet of white sturgeon following the overbite clam invasion and subsequent shift in the SFE benthic prey assemblage. Gut content analysis was used to compare white sturgeon prey composition and importance between the pre- and post-invasion periods. Additionally, stable isotope analysis was employed to estimate the assimilation of prey items to sturgeon biomass. Overbite clams dominated diets in the post-invasion period, accounting for 82 to 93% of total volume. Stable isotope analysis confirmed the importance of this prey item, although their assimilated contribution to sturgeon biomass was estimated to be less (70 to 83%) than gut contents indicated. The frequency of fish in white sturgeon guts increased in the post-invasion period, and isotope analysis indicated relatively large contributions of fish to sturgeon biomass (3.7 to 19%). The trophic adaptability of white sturgeon has allowed them to exploit this new prey source (overbite clam). Future conservation and restoration efforts must consider a potentially destabilized food web given the large importance of a single prey item.

  17. Antipredator responses by native mosquitofish to non-native cichlids: An examination of the role of prey naiveté

    USGS Publications Warehouse

    Rehage, Jennifer S.; Dunlop, Katherine L.; Loftus, William F.

    2009-01-01

    The strong impact of non-native predators in aquatic systems is thought to relate to the evolutionary naiveté of prey. Due to isolation and limited dispersal, this naiveté may be relatively high in freshwater systems. In this study, we tested this notion by examining the antipredator response of native mosquitofish, Gambusia holbrooki, to two non-native predators found in the Everglades, the African jewelfish,Hemichromis letourneuxi, and the Mayan cichlid, Cichlasoma urophthalmus. We manipulated prey naiveté by using two mosquitofish populations that varied in their experience with the recent invader, the African jewelfish, but had similar levels of experience with the longer-established Mayan cichlid. Specifically, we tested these predictions: (1) predator hunting modes differed between the two predators, (2) predation rates would be higher by the novel jewelfish predator, (3) particularly on the naive population living where jewelfish have not invaded yet, (4) antipredator responses would be stronger to Mayan cichlids due to greater experience and weaker and/or ineffective to jewelfish, and (5) especially weakest by the naive population. We assayed prey and predator behavior, and prey mortality in lab aquaria where both predators and prey were free-ranging. Predator hunting modes and habitat domains differed, with jewelfish being more active search predators that used slightly higher parts of the water column and less of the habitat structure relative to Mayan cichlids. In disagreement with our predictions, predation rates were similar between the two predators, antipredator responses were stronger to African jewelfish (except for predator inspections), and there was no difference in response between jewelfish-savvy and jewelfish-naive populations. These results suggest that despite the novelty of introduced predators, prey may be able to respond appropriately if non-native predator archetypes are similar enough to those of native predators, if prey rely

  18. Adaptive female-mimicking behavior in a scorpionfly.

    PubMed

    Thornhill, R

    1979-07-27

    This study provides a clear example of female-mimicking behavior by males in insects and evaluates quantitatively the adaptive significance of this behavior, which is poorly understood in many other organisms. Males of Hylobittacus apicalis provide females with a prey arthropod during copulation. Some males mimic female behavior when interacting with males that have captured nuptial prey, resulting in males stealing prey which they will use for copulation. Males that pirate prey copulate more frequently and probably incur fewer predation-related risks. PMID:17790854

  19. Prey species as possible sources of PBDE exposures for peregrine falcons (Falco peregrinus) nesting in major California cities.

    PubMed

    Park, June-Soo; Fong, Alison; Chu, Vivian; Holden, Arthur; Linthicum, Janet; Hooper, Kim

    2011-04-01

    Our earlier findings indicate that (1) peregrine falcons (Falco peregrinus anatum Bonaparte) nesting in major California cities have among the highest polybrominated diphenyl ether (PBDE) levels in the world (max ∑PBDEs=100 ppm), and (2) Big City peregrines have higher levels and proportions of the higher-brominated congeners (hepta- to deca-BDEs) than do their Coastal counterparts. In this study we classified the prey species (n =185) from the remains of prey (feathers) at 38 peregrine nest sites over 25 years (1974-1998). We grouped the prey species into 15 categories based on diet and found distinctly different prey patterns for Big City vs. Coastal peregrines. Big City peregrines had a higher (almost three times) weight percentage intake of food waste-eating birds (e.g., rock pigeons, Columba livia) than Coastal peregrines. These differing prey patterns suggest diet as a potential source of the unusually high levels and proportions of higher-brominated PBDEs in Big City peregrines. The relative contributions of diet and dust (e.g., preening) exposure to PBDE patterns in Big City peregrines will be explored in future investigations. PMID:20514482

  20. Neuroethology of prey capture in the barn owl (Tyto alba L.).

    PubMed

    Wagner, Hermann; Kettler, Lutz; Orlowski, Julius; Tellers, Philipp

    2013-01-01

    Barn owls are a model system for studying prey capture. These animals can catch mice by hearing alone, but use vision whenever light conditions allow this. The silent flight, the frontally oriented eyes, and the facial ruffs are specializations that evolved to optimize prey capture. The auditory system is characterized by high absolute sensitivity, a use of interaural time difference for azimuthal sound-localization over almost the total hearing range up to at least 9 kHz, and the use of interaural level difference for elevational sound localization in the upper frequency range. Response latencies towards auditory targets were shortened by covert attention, while overt attention helped to orient towards salient visual objects. However, only 20% of the fixation movements could be explained by the saliency of the fixated objects, suggesting a top-down control of attention. In a visual-search experiment the birds turned earlier and more often towards and spent more time at salient objects. The visual system also exhibits high absolute sensitivity, while the spatial resolution is not particularly high. Last but not least, head movements may be classified as fixations, translations, and rotations combined with translations. These motion primitives may be combined to complex head-movement patterns. With the expected easy availability of genetic techniques for specialists in the near future and the possibility to apply the findings in biomimetic devices prey capture in barn owls will remain an exciting field in the future. PMID:22510644

  1. Energy and protein content of coyote prey in southeastern Idaho

    SciTech Connect

    MacCracken, J.G.; Hansen, R.M.

    1986-04-30

    Gross energy, digestible energy, crude protein, and digestible crude protein were estimated for two leporids and five rodents that were the primary prey of coyotes (Canis latrans) in southeastern Idaho. Digestible protein estimates differed (38%-54%) more than digestible energy (3.5-4.4 kcal), in the prey examined. 15 references, 1 table.

  2. Red fox prey demands and implications to prairie duck production

    USGS Publications Warehouse

    Sargeant, A.B.

    1978-01-01

    Experiments were conducted during spring and summer with 33 red foxes (Vulpes vulpes) to determine prey demands, feeding characteristics, and growth rates using natural foods. Pups began eating prey the 4th week after birth. Then, prey consumption averaged 1.38 and 1.90 kg/pup/week for weeks 5-8 and 9-12 of the denning season respectively, and 2.54 kg/pup/week for the postdenning period. Feeding by adults averaged 2.25 kg/adult/week. Free water was not needed by either pups or adults. About 90 percent of the prey offered to pups on simulated natural diets was consumed, remains varied with prey availability and prey type. Prey biomass required by a typical fox family was estimated at 18.5 kg/km2 for the 12-week denning season and 2.4 kg/km2/week for the postdenning period. Because of the large prey demands, ducks could represent a small part of the foxes' diet and yet be of consequence to the productivity of particular species. An example is provided for the mallard (Anas platyrhynchos).

  3. Top predators negate the effect of mesopredators on prey physiology.

    PubMed

    Palacios, Maria M; Killen, Shaun S; Nadler, Lauren E; White, James R; McCormick, Mark I

    2016-07-01

    Predation theory and empirical evidence suggest that top predators benefit the survival of resource prey through the suppression of mesopredators. However, whether such behavioural suppression can also affect the physiology of resource prey has yet to be examined. Using a three-tier reef fish food web and intermittent-flow respirometry, our study examined changes in the metabolic rate of resource prey exposed to combinations of mesopredator and top predator cues. Under experimental conditions, the mesopredator (dottyback, Pseudochromis fuscus) continuously foraged and attacked resource prey (juveniles of the damselfish Pomacentrus amboinensis) triggering an increase in prey O2 uptake by 38 ± 12·9% (mean ± SE). The visual stimulus of a top predator (coral trout, Plectropomus leopardus) restricted the foraging activity of the mesopredator, indirectly allowing resource prey to minimize stress and maintain routine O2 uptake. Although not as strong as the effect of the top predator, the sight of a large non-predator species (thicklip wrasse, Hemigymnus melapterus) also reduced the impact of the mesopredator on prey metabolic rate. We conclude that lower trophic-level species can benefit physiologically from the presence of top predators through the behavioural suppression that top predators impose on mesopredators. By minimizing the energy spent on mesopredator avoidance and the associated stress response to mesopredator attacks, prey may be able to invest more energy in foraging and growth, highlighting the importance of the indirect, non-consumptive effects of top predators in marine food webs. PMID:27113316

  4. Prey Vulnerability Limits Top-Down Control and Alters Reciprocal Feedbacks in a Subsidized Model Food Web

    PubMed Central

    Atlas, William I.; Palen, Wendy J.

    2014-01-01

    Resource subsidies increase the productivity of recipient food webs and can affect ecosystem dynamics. Subsidies of prey often support elevated predator biomass which may intensify top-down control and reduce the flow of reciprocal subsidies into adjacent ecosystems. However, top-down control in subsidized food webs may be limited if primary consumers posses morphological or behavioral traits that limit vulnerability to predation. In forested streams, terrestrial prey support high predator biomass creating the potential for strong top-down control, however armored primary consumers often dominate the invertebrate assemblage. Using empirically based simulation models, we tested the response of stream food webs to variations in subsidy magnitude, prey vulnerability, and the presence of two top predators. While terrestrial prey inputs increased predator biomass (+12%), the presence of armored primary consumers inhibited top-down control, and diverted most aquatic energy (∼75%) into the riparian forest through aquatic insect emergence. Food webs without armored invertebrates experienced strong trophic cascades, resulting in higher algal (∼50%) and detrital (∼1600%) biomass, and reduced insect emergence (−90%). These results suggest prey vulnerability can mediate food web responses to subsidies, and that top-down control can be arrested even when predator-invulnerable consumers are uncommon (20%) regardless of the level of subsidy. PMID:24465732

  5. Personality, Perceived Environment, and Behavior Systems Related to Future Smoking Intentions among Youths: An Application of Problem-Behavior Theory in Shanghai, China

    PubMed Central

    Na, Li; He, Yaping; Redmon, Pam; Qiao, Yun; Ma, Jin

    2015-01-01

    Background Smoking among youths is a worldwide problem, particularly in China. Many endogenous and environmental factors influence smokers’ intentions to smoke; therefore, a comprehensive model is needed to understand the significance and relationship of predictors. This study aimed to develop a prediction model based on problem-behavior theory (PBT) to interpret intentions to smoke among Chinese youths. Methods We conducted a cross-sectional study of 26,675 adolescents from junior, senior, and vocational high schools in Shanghai, China. Data on smoking status, smoking knowledge, attitude toward smoking, parents’ and peers’ smoking, and media exposure to smoking were collected from students. A structural equation model was used to assess the developed prediction model. Results The experimental smoking rate and current smoking rate among the students were 11.0% and 3%, respectively. Our constructed model showed an acceptable fit to the data (comparative fit index = 0.987, root-mean-square error of approximation = 0.034). Intention to smoke was predicted by perceived environment (β = 0.455, P < 0.001) system consisting of peer smoking (β = 0.599, P < 0.001), parent smoking (β = 0.152, P < 0.001), and media exposure to smoking (β = 0.226, P < 0.001), and behavior system (β = 0.487, P < 0.001) consisting of tobacco experimentation (β = 0.663, P < 0.001) and current smoking (β = 0.755, P < 0.001). Smoking intention was irrelevant for personality system in students (β = -0.113, P>0.05) which consisted of acceptance of tobacco use (β = 0.668, P < 0.001) and academic performance (β = 0.171, P < 0.001). Conclusion The PBT-based model we developed provides a good understanding of the predictors of intentions to smoke and it suggests future interventions among youths should focus on components in perceived environment and behavior systems, and take into account the moderating effects of personality system. PMID:25826611

  6. Arginine: A Potent Prey Attractant to Predatory Newts in Mountain Streams

    NASA Astrophysics Data System (ADS)

    Ferrer, R. P.; Zimmer, R. K.

    2005-05-01

    Chemoreception of aquatic organisms has been well-studied in the laboratory, but rarely in the field. The California newt, Taricha torosa, in natural stream habitats is an excellent animal for exploring behavioral responses to prey odors. Here, we selected 13 amino acids for field bioassays based on their concentrations in prey tissue extracts. Bioassays were calibrated for stimulus dilution by means of fluorescent dye releases and flow-through spectrofluorometry. Moreover, hydrodynamic properties of stream flows were determined using an electromagnetic current meter. Of all amino acids tested, only arginine, alanine and glycine were significantly attractive (relative to stream water controls). These three substances caused free-ranging newts to turn upstream and swim towards the odor sources. Additional experiments showed that arginine was the most effective attractant, evoking plume-tracking behavior at concentrations as low as 10 nM. In subsequent trials, nine arginine analogs were tested, but each compound failed to elicit a significant response. Even subtle changes to arginine, such as the addition of a single carbon to the side chain, destroyed all bioactivity. Within its natural habitat, the California newt thus exhibits keen sensitivity and narrow tuning to the free amino acid, arginine, a chemical signal of its prey.

  7. Owls May Use Faeces and Prey Feathers to Signal Current Reproduction

    PubMed Central

    Penteriani, Vincenzo; del Mar Delgado, Maria

    2008-01-01

    Background Many animals communicate by marking focal elements of their home range with different kinds of materials. Visual signaling has been demonstrated to play a previously unrecognized role in the intraspecific communication of eagle owls (Bubo bubo), in both territorial and parent-offspring contexts. Visual signals may play a role in a variety of circumstances in this crepuscular and nocturnal species. Methodology/Principal Findings Here, we report that a large amount of extremely visible white faeces and prey feathers appear during the breeding season on posts and plucking sites in proximity to the nest, potentially representing a way for eagle owls to mark their territory. We present descriptive and experimental evidence showing that faeces and prey remains could act as previously unrecognized visual signals in a nocturnal avian predator. This novel signaling behavior could indicate the owls' current reproductive status to potential intruders, such as other territorial owls or non-breeding floaters. Faeces and prey feather markings may also advertise an owl's reproductive status or function in mate-mate communication. Conclusions/Significance We speculate that faeces marks and plucking may represent an overlooked but widespread method for communicating current reproduction to conspecifics. Such marking behavior may be common in birds, and we may now be exploring other questions and mechanisms in territoriality. PMID:18714382

  8. Clamming up: environmental forces diminish the perceptive ability of bivalve prey.

    PubMed

    Smee, Delbert L; Weissburg, Marc J

    2006-06-01

    The lethal and nonlethal impacts of predators in marine systems are often mediated via reciprocal detection of waterborne chemical signals between consumers and prey. Local flow environments can enhance or impair the chemoreception ability of consumers, but the effect of hydrodynamics on detection of predation risk by prey has not been investigated. Using clams as our model organism, we investigated two specific questions: (1) Can clams decrease their mortality by responding to predators? (2) Do fluid forces affect the ability of clams to detect approaching predators? Previous research has documented a decrease in clam feeding (pumping) in response to a neighboring predator. We determined the benefits of this behavior to survivorship by placing clams in the field with knobbed whelk or blue crab predators caged nearby and compared mortality between these clams and clams near a cage-only control. Significantly more clams survived in areas containing a caged predator, suggesting that predator-induced alterations in feeding reduce clam mortality in the field. We ascertained the effect of fluid forces on clam perception of predators in a laboratory flume by comparing the feeding (pumping) behavior of clams in response to crabs and whelks in flows of 3 and 11 cm/s. Clams pumped significantly less in the presence of predators, but their reaction to blue crabs diminished in the higher velocity flow, while their response to whelks remained constant in both flows. Thus, clam reactive distance to blue crabs was affected by fluid forces, but hydrodynamic effects on clam perceptive distance was predator specific. After predators were removed, clams exposed to whelks took significantly longer to resume feeding than those exposed to blue crabs. Our results suggest that prey perception of predators can be altered by physical forces. Prey detection of predators is the underlying mechanism for trait-mediated indirect interactions (TMIIs), and recent research has documented the

  9. Bioeconomic harvesting of a prey-predator fishery.

    PubMed

    Das, Tapasi; Mukherjee, R N; Chaudhuri, K S

    2009-09-01

    This paper deals with the problem of non-selective harvesting of a prey-predator system by using a reasonable catch-rate function instead of usual catch-per-unit-efforthypothesis. Here both the prey and the predator species obey the law of logistic growth. We have taken the predator functional response to prey density in such a form that each predator's functional response to the prey density approaches a constant as the prey population increases. Boundedness of the exploited system is examined. The existence of its steady states and their stability (local and global) are studied using Eigenvalue analysis. The existence of bionomic equilibria has been illustrated using a numerical example. The problem of determining the optimal harvesting policy is then solved by using Pontryagin's maximum principle. PMID:22880894

  10. A theory of vibrational prey localization in two dimensions: the sand scorpion

    NASA Astrophysics Data System (ADS)

    van Hemmen, J. Leo

    2000-03-01

    Sand scorpions, and many other arachnids, find their prey at night by localizing the source of mechanical waves produced by prey movements. Substrate vibrations propagating through sand evoke stimulus-locked action potentials from slit sensilla on the scorpion's eight `feet' (tarsi). We present a neuronal model to account for stimulus angle determination in a two-dimensional plane using a population of second-order neurons, each receiving excitatory input from one tarsus and inhibition from a triad opposite to it. This input opens a time window whose width determines the firing probability of each of the second-order neurons. The population then `votes' for the direction. Stochastic resonance is realized through tuning the balance between excitation and inhibition. The agreement with behavioral experiments on sand scorpions is excellent.

  11. Dynamic analysis of a fractional order delayed predator-prey system with harvesting.

    PubMed

    Song, Ping; Zhao, Hongyong; Zhang, Xuebing

    2016-06-01

    In the study, we consider a fractional order delayed predator-prey system with harvesting terms. Our discussion is divided into two cases. Without harvesting, we investigate the stability of the model, as well as deriving some criteria by analyzing the associated characteristic equation. With harvesting, we investigate the dynamics of the system from the aspect of local stability and analyze the influence of harvesting to prey and predator. Finally, numerical simulations are presented to verify our theoretical results. In addition, using numerical simulations, we investigate the effects of fractional order and harvesting terms on dynamic behavior. Our numerical results show that fractional order can affect not only the stability of the system without harvesting terms, but also the switching times from stability to instability and to stability. The harvesting can convert the equilibrium point, the stability and the stability switching times. PMID:27026265

  12. Predatory Bacteriovorax Communities Ordered by Various Prey Species

    PubMed Central

    Chen, Huan; Young, Shanterial; Berhane, Timkhite-Kulu; Williams, Henry N.

    2012-01-01

    The role of predation in altering microbial communities has been studied for decades but few examples are known for bacterial predators. Bacteriovorax are halophilic prokaryotes that prey on susceptible Gram-negative bacteria. We recently reported novel observations on the differential selection of Bacteriovorax phylotypes by two different prey, Vibrio parahaemolyticus and Vibrio vulnificus. However, the conclusion is restricted by the limited number of prey tested. In this study, we have conducted two independent investigations involving eight species of prey bacteria while using V. vulnificus and V. parahaemolytics as reference strains. Water samples collected from Dry Bar, Apalachicola Bay were used to establish microcosms which were respectively spiked with prey strains Vibrio cholerae, Escherichia coli or Pseudomonas putida to examine the response of native Bacteriovorax to freshwater bacteria. Indigenous Vibrio sp., Pseudoalteromonas sp., Photobacterium sp. and a clinical strain of V. vulnificus were also tested for the impact of saltwater prey on the Bacteriovorax community. At 24 hour intervals, optical density of the microcosm samples and the abundance of Bacteriovorax were measured over five days. The predominant Bacteriovorax plaques were selected and analyzed by 16S rRNA gene amplification and sequencing. In addition, the impacts of prey on predator population and bacterial community composition were investigated using culture independent denaturing gradient gel electrophoresis. Strikingly, Cluster IV was found consistently as the predominant phylotype produced by the freshwater prey. For all saltwater prey, subgroups of Bacteriovorax phylotype IX were the major predators recovered. The results suggest that prey is an important factor along with temperature, salinity and other environmental parameters in shaping Bacteriovorax communities in aquatic systems. PMID:22461907

  13. Predatory Bacteriovorax communities ordered by various prey species.

    PubMed

    Chen, Huan; Young, Shanterial; Berhane, Timkhite-Kulu; Williams, Henry N

    2012-01-01

    The role of predation in altering microbial communities has been studied for decades but few examples are known for bacterial predators. Bacteriovorax are halophilic prokaryotes that prey on susceptible gram-negative bacteria. We recently reported novel observations on the differential selection of Bacteriovorax phylotypes by two different prey, Vibrio parahaemolyticus and Vibrio vulnificus. However, the conclusion is restricted by the limited number of prey tested. In this study, we have conducted two independent investigations involving eight species of prey bacteria while using V. vulnificus and V. parahaemolytics as reference strains. Water samples collected from Dry Bar, Apalachicola Bay were used to establish microcosms which were respectively spiked with prey strains Vibrio cholerae, Escherichia coli or Pseudomonas putida to examine the response of native Bacteriovorax to freshwater bacteria. Indigenous Vibrio sp., Pseudoalteromonas sp., Photobacterium sp. and a clinical strain of V. vulnificus were also tested for the impact of saltwater prey on the Bacteriovorax community. At 24 hour intervals, optical density of the microcosm samples and the abundance of Bacteriovorax were measured over five days. The predominant Bacteriovorax plaques were selected and analyzed by 16S rRNA gene amplification and sequencing. In addition, the impacts of prey on predator population and bacterial community composition were investigated using culture independent denaturing gradient gel electrophoresis. Strikingly, Cluster IV was found consistently as the predominant phylotype produced by the freshwater prey. For all saltwater prey, subgroups of Bacteriovorax phylotype IX were the major predators recovered. The results suggest that prey is an important factor along with temperature, salinity and other environmental parameters in shaping Bacteriovorax communities in aquatic systems. PMID:22461907

  14. Chemical Prey Luring in Jackson's Chameleons.

    PubMed

    Preest, Marion R; Ward, Matthew J; Poon, Thomas; Hermanson, John W

    2016-01-01

    Lizards in the family Chamaeleonidae have been described as wiping a viscous substance from a pouch (the temporal pouch) at the angle of the jaw on branches and then capturing flies that land near the area where the wiping occurs. We confirmed the presence of this pouch in Jackson's chameleons. Histological work suggested that the material contained within is a result of decomposition of food and sloughed skin that has been trapped in the pouch rather than a glandular secretion. Gas chromatography-mass spectrometry indicated the presence of compounds that are both volatile and odiferous and similar to insect pheromones. Choice tests with houseflies revealed attraction to the temporal pouch material. Some authors have speculated that the temporal pouch material serves a function in territory marking and/or predator deterrence. While it may play these roles, our results suggest that it also plays a role in chemical luring of prey. PMID:27082721

  15. Diet composition and terrestrial prey selection of the Laysan teal on Laysan Island

    USGS Publications Warehouse

    Reynolds, M.H.; Slotterback, J.W.; Walters, J.R.

    2006-01-01

    The Laysan teal (Anas laysanensis) is an endangered dabbling duck endemic to the Hawaiian Archipelago but currently restricted to a single breeding population on Laysan Island. We studied its diet using fecal analysis and behavioral observations. Laysan teal fecal samples (N=118) contained prey items in 15 primary prey categories with a mean of 2.9 (range 0-7) taxa per sample. Sixty-two of these fecal samples were quantified with 2,270 prey items identified (mean items per sample 37; range 0-205). Based on fecal analysis and behavioral observations, we learned that the Laysan teal is not strictly a macroinsectivore as previously reported, but consumed seeds, succulent leaves, and algae, in addition to adult and larval diptera, ants, lepidoptera, coleoptera, and Artemia. We compared abundance of invertebrates from two terrestrial foraging substrates, soil and standing vegetation, to the abundance of invertebrate prey items counted in fecal samples collected from these habitats for the same period. In the soil substrate, Laysan teal selected two of the most abundant invertebrates, lepidoptera larvae and coleoptera. In the standing vegetation, Laysan teal selected the most abundant taxa: coleoptera. Amphipods were consumed in proportion to their abundance, and small gastropods (Tornatellides sp.), isopods, and arachnids were avoided or were identified in fecal matter in disproportion to their abundance in the foraging habitat. We compared fecal composition of samples collected in aquatic and terrestrial habitats and detected significant differences in samples' species compositions. The conservation implications of the adult Laysan teal's diet are positive, since results indicate that the Laysan teal are opportunistic insectivores, and exhibit dietary flexibility that includes seeds and other food. Dietary flexibility improves the possibility of successfully reestablishing populations on other predator-free islands.

  16. Wave propagation in predator-prey systems

    NASA Astrophysics Data System (ADS)

    Fu, Sheng-Chen; Tsai, Je-Chiang

    2015-12-01

    In this paper, we study a class of predator-prey systems of reaction-diffusion type. Specifically, we are interested in the dynamical behaviour for the solution with the initial distribution where the prey species is at the level of the carrying capacity, and the density of the predator species has compact support, or exponentially small tails near x=+/- ∞ . Numerical evidence suggests that this will lead to the formation of a pair of diverging waves propagating outwards from the initial zone. Motivated by this phenomenon, we establish the existence of a family of travelling waves with the minimum speed. Unlike the previous studies, we do not use the shooting argument to show this. Instead, we apply an iteration process based on Berestycki et al 2005 (Math Comput. Modelling 50 1385-93) to construct a set of super/sub-solutions. Since the underlying system does not enjoy the comparison principle, such a set of super/sub-solutions is not based on travelling waves, and in fact the super/sub-solutions depend on each other. With the aid of the set of super/sub-solutions, we can construct the solution of the truncated problem on the finite interval, which, via the limiting argument, can in turn generate the wave solution. There are several advantages to this approach. First, it can remove the technical assumptions on the diffusivities of the species in the existing literature. Second, this approach is of PDE type, and hence it can shed some light on the spreading phenomenon indicated by numerical simulation. In fact, we can compute the spreading speed of the predator species for a class of biologically acceptable initial distributions. Third, this approach might be applied to the study of waves in non-cooperative systems (i.e. a system without a comparison principle).

  17. Modelling the Effects of Prey Size and Distribution on Prey Capture Rates of Two Sympatric Marine Predators

    PubMed Central

    Thaxter, Chris B.; Daunt, Francis; Grémillet, David; Harris, Mike P.; Benvenuti, Silvano; Watanuki, Yutaka; Hamer, Keith C.; Wanless, Sarah

    2013-01-01

    Understanding how prey capture rates are influenced by feeding ecology and environmental conditions is fundamental to assessing anthropogenic impacts on marine higher predators. We compared how prey capture rates varied in relation to prey size, prey patch distribution and prey density for two species of alcid, common guillemot (Uria aalge) and razorbill (Alca torda) during the chick-rearing period. We developed a Monte Carlo approach parameterised with foraging behaviour from bird-borne data loggers, observations of prey fed to chicks, and adult diet from water-offloading, to construct a bio-energetics model. Our primary goal was to estimate prey capture rates, and a secondary aim was to test responses to a set of biologically plausible environmental scenarios. Estimated prey capture rates were 1.5±0.8 items per dive (0.8±0.4 and 1.1±0.6 items per minute foraging and underwater, respectively) for guillemots and 3.7±2.4 items per dive (4.9±3.1 and 7.3±4.0 items per minute foraging and underwater, respectively) for razorbills. Based on species' ecology, diet and flight costs, we predicted that razorbills would be more sensitive to decreases in 0-group sandeel (Ammodytes marinus) length (prediction 1), but guillemots would be more sensitive to prey patches that were more widely spaced (prediction 2), and lower in prey density (prediction 3). Estimated prey capture rates increased non-linearly as 0-group sandeel length declined, with the slope being steeper in razorbills, supporting prediction 1. When prey patches were more dispersed, estimated daily energy expenditure increased by a factor of 3.0 for guillemots and 2.3 for razorbills, suggesting guillemots were more sensitive to patchier prey, supporting prediction 2. However, both species responded similarly to reduced prey density (guillemot expenditure increased by 1.7; razorbill by 1.6), thus not supporting prediction 3. This bio-energetics approach complements other foraging models in predicting likely

  18. Negotiating a noisy, information-rich environment in search of cryptic prey: olfactory predators need patchiness in prey cues.

    PubMed

    Carthey, Alexandra J R; Bytheway, Jenna P; Banks, Peter B

    2011-07-01

    1. Olfactory predator search processes differ fundamentally to those based on vision, particularly when odour cues are deposited rather than airborne or emanating from a point source. When searching for visually cryptic prey that may have moved some distance from a deposited odour cue, cue context and spatial variability are the most likely sources of information about prey location available to an olfactory predator. 2. We tested whether the house mouse (Mus domesticus), a model olfactory predator, would use cue context and spatial variability when searching for buried food items; specifically, we tested the effect of varying cue patchiness, odour strength, and cue-prey association on mouse foraging success. 3. Within mouse- and predator-proof enclosures, we created grids of 100 sand-filled Petri dishes and buried peanut pieces in a set number of these patches to represent visually cryptic 'prey'. By adding peanut oil to selected dishes, we varied the spatial distribution of prey odour relative to the distribution of prey patches in each grid, to reflect different levels of cue patchiness (Experiment 1), odour strength (Experiment 2) and cue-prey association (Experiment 3). We measured the overnight foraging success of individual mice (percentage of searched patches containing prey), as well as their foraging activity (percentage of patches searched), and prey survival (percentage of unsearched prey patches). 4. Mouse foraging success was highest where odour cues were patchy rather than uniform (Experiment 1), and where cues were tightly associated with prey location, rather than randomly or uniformly distributed (Experiment 3). However, when cues at prey patches were ten times stronger than a uniformly distributed weak background odour, mice did not improve their foraging success over that experienced when cues were of uniform strength and distribution (Experiment 2). 5. These results suggest that spatial variability and cue context are important means by which

  19. Acoustic shadows help gleaning bats find prey, but may be defeated by prey acoustic camouflage on rough surfaces.

    PubMed

    Clare, Elizabeth L; Holderied, Marc W

    2015-01-01

    Perceptual abilities of animals, like echolocating bats, are difficult to study because they challenge our understanding of non-visual senses. We used novel acoustic tomography to convert echoes into visual representations and compare these cues to traditional echo measurements. We provide a new hypothesis for the echo-acoustic basis of prey detection on surfaces. We propose that bats perceive a change in depth profile and an 'acoustic shadow' cast by prey. The shadow is more salient than prey echoes and particularly strong on smooth surfaces. This may explain why bats look for prey on flat surfaces like leaves using scanning behaviour. We propose that rather than forming search images for prey, whose characteristics are unpredictable, predators may look for disruptions to the resting surface (acoustic shadows). The fact that the acoustic shadow is much fainter on rougher resting surfaces provides the first empirical evidence for 'acoustic camouflage' as an anti-predator defence mechanism. PMID:26327624

  20. Analysis of Prey-Predator Three Species Fishery Model with Harvesting Including Prey Refuge and Migration

    NASA Astrophysics Data System (ADS)

    Roy, Sankar Kumar; Roy, Banani

    In this article, a prey-predator system with Holling type II functional response for the predator population including prey refuge region has been analyzed. Also a harvesting effort has been considered for the predator population. The density-dependent mortality rate for the prey, predator and super predator has been considered. The equilibria of the proposed system have been determined. Local and global stabilities for the system have been discussed. We have used the analytic approach to derive the global asymptotic stabilities of the system. The maximal predator per capita consumption rate has been considered as a bifurcation parameter to evaluate Hopf bifurcation in the neighborhood of interior equilibrium point. Also, we have used fishing effort to harvest predator population of the system as a control to develop a dynamic framework to investigate the optimal utilization of the resource, sustainability properties of the stock and the resource rent is earned from the resource. Finally, we have presented some numerical simulations to verify the analytic results and the system has been analyzed through graphical illustrations.

  1. Flexibility in locomotor-feeding integration during prey capture in varanid lizards: effects of prey size and velocity.

    PubMed

    Montuelle, Stéphane J; Herrel, Anthony; Libourel, Paul-Antoine; Daillie, Sandra; Bels, Vincent L

    2012-11-01

    Feeding movements are adjusted in response to food properties, and this flexibility is essential for omnivorous predators as food properties vary routinely. In most lizards, prey capture is no longer considered to solely rely on the movements of the feeding structures (jaws, hyolingual apparatus) but instead is understood to require the integration of the feeding system with the locomotor system (i.e. coordination of movements). Here, we investigated flexibility in the coordination pattern between jaw, neck and forelimb movements in omnivorous varanid lizards feeding on four prey types varying in length and mobility: grasshoppers, live newborn mice, adult mice and dead adult mice. We tested for bivariate correlations between 3D locomotor and feeding kinematics, and compared the jaw-neck-forelimb coordination patterns across prey types. Our results reveal that locomotor-feeding integration is essential for the capture of evasive prey, and that different jaw-neck-forelimb coordination patterns are used to capture different prey types. Jaw-neck-forelimb coordination is indeed significantly altered by the length and speed of the prey, indicating that a similar coordination pattern can be finely tuned in response to prey stimuli. These results suggest feed-forward as well as feed-back modulation of the control of locomotor-feeding integration. As varanids are considered to be specialized in the capture of evasive prey (although they retain their ability to feed on a wide variety of prey items), flexibility in locomotor-feeding integration in response to prey mobility is proposed to be a key component in their dietary specialization. PMID:22899521

  2. The effect of structural complexity, prey density, and "predator-free space" on prey survivorship at created oyster reef mesocosms

    USGS Publications Warehouse

    Humphries, Austin T.; La Peyre, Megan K.; Decossas, Gary A.

    2011-01-01

    Interactions between predators and their prey are influenced by the habitat they occupy. Using created oyster (Crassostrea virginica) reef mesocosms, we conducted a series of laboratory experiments that created structure and manipulated complexity as well as prey density and “predator-free space” to examine the relationship between structural complexity and prey survivorship. Specifically, volume and spatial arrangement of oysters as well as prey density were manipulated, and the survivorship of prey (grass shrimp, Palaemonetes pugio) in the presence of a predator (wild red drum, Sciaenops ocellatus) was quantified. We found that the presence of structure increased prey survivorship, and that increasing complexity of this structure further increased survivorship, but only to a point. This agrees with the theory that structural complexity may influence predator-prey dynamics, but that a threshold exists with diminishing returns. These results held true even when prey density was scaled to structural complexity, or the amount of “predator-free space” was manipulated within our created reef mesocosms. The presence of structure and its complexity (oyster shell volume) were more important in facilitating prey survivorship than perceived refugia or density-dependent prey effects. A more accurate indicator of refugia might require “predator-free space” measures that also account for the available area within the structure itself (i.e., volume) and not just on the surface of a structure. Creating experiments that better mimic natural conditions and test a wider range of “predator-free space” are suggested to better understand the role of structural complexity in oyster reefs and other complex habitats.

  3. Current Knowledge and Future Research on Infant Feeding in the Context of HIV: Basic, Clinical, Behavioral, and Programmatic Perspectives12

    PubMed Central

    Young, Sera L.; Mbuya, Mduduzi N. N.; Chantry, Caroline J.; Geubbels, Eveline P.; Israel-Ballard, Kiersten; Cohan, Deborah; Vosti, Stephen A.; Latham, Michael C.

    2011-01-01

    In 2008, between 129,000 and 194,000 of the 430,000 pediatric HIV infections worldwide were attributable to breastfeeding. Yet in many settings, the health, economic, and social consequences of not breastfeeding would have dire consequences for many more children. In the first part of this review we provide an overview of current knowledge about infant feeding in the context of HIV. Namely, we describe the benefits and risks of breastmilk, the evolution of recommended infant feeding modalities in high-income and low-income countries in the last two decades, and contextualize the recently revised guidelines for infant feeding in the context of HIV current knowledge. In the second section, we suggest areas for future research on the postnatal prevention of mother-to-child transmission of HIV (PMTCT) in developing and industrialized countries. We suggest two shifts in perspective. The first is to evaluate PMTCT interventions more holistically, to include the psychosocial and economic consequences as well as the biomedical ones. The second shift in perspective should be one that contextualizes postnatal PMTCT efforts in the cascade of maternal health services. We conclude by discussing basic, clinical, behavioral, and programmatic research questions pertaining to a number of PMTCT efforts, including extended postnatal ARV prophylaxis, exclusive breastfeeding promotion, counseling, breast milk pasteurization, breast milk banking, novel techniques for making breast milk safer, and optimal breastfeeding practices. We believe the research efforts outlined here will maximize the number of healthy, thriving, HIV-free children around the world. PMID:22332055

  4. Planning for the Future: A Model for Using the Principles of Transition to Guide the Development of Behavior Intervention Plans

    ERIC Educational Resources Information Center

    Mueller, Tracy Gershwin; Bassett, Diane S.; Brewer, Robin D.

    2012-01-01

    The Individuals with Disabilities Education Act (IDEA) mandates the implementation of a behavior intervention plan based on a functional behavioral assessment when a student's behavior necessitates disciplinary actions. However, IDEA does not provide any clear guidelines as to what the plans should contain nor how they can address behaviors that…

  5. A snail-eating snake recognizes prey handedness

    PubMed Central

    Danaisawadi, Patchara; Asami, Takahiro; Ota, Hidetoshi; Sutcharit, Chirasak; Panha, Somsak

    2016-01-01

    Specialized predator-prey interactions can be a driving force for their coevolution. Southeast Asian snail-eating snakes (Pareas) have more teeth on the right mandible and specialize in predation on the clockwise-coiled (dextral) majority in shelled snails by soft-body extraction. Snails have countered the snakes’ dextral-predation by recurrent coil reversal, which generates diverse counterclockwise-coiled (sinistral) prey where Pareas snakes live. However, whether the snake predator in turn evolves any response to prey reversal is unknown. We show that Pareas carinatus living with abundant sinistrals avoids approaching or striking at a sinistral that is more difficult and costly to handle than a dextral. Whenever it strikes, however, the snake succeeds in predation by handling dextral and sinistral prey in reverse. In contrast, P. iwasakii with little access to sinistrals on small peripheral islands attempts and frequently misses capturing a given sinistral. Prey-handedness recognition should be advantageous for right-handed snail-eating snakes where frequently encountering sinistrals. Under dextral-predation by Pareas snakes, adaptive fixation of a prey population for a reversal gene instantaneously generates a sinistral species because interchiral mating is rarely possible. The novel warning, instead of sheltering, effect of sinistrality benefitting both predators and prey could further accelerate single-gene ecological speciation by left-right reversal. PMID:27046345

  6. A snail-eating snake recognizes prey handedness.

    PubMed

    Danaisawadi, Patchara; Asami, Takahiro; Ota, Hidetoshi; Sutcharit, Chirasak; Panha, Somsak

    2016-01-01

    Specialized predator-prey interactions can be a driving force for their coevolution. Southeast Asian snail-eating snakes (Pareas) have more teeth on the right mandible and specialize in predation on the clockwise-coiled (dextral) majority in shelled snails by soft-body extraction. Snails have countered the snakes' dextral-predation by recurrent coil reversal, which generates diverse counterclockwise-coiled (sinistral) prey where Pareas snakes live. However, whether the snake predator in turn evolves any response to prey reversal is unknown. We show that Pareas carinatus living with abundant sinistrals avoids approaching or striking at a sinistral that is more difficult and costly to handle than a dextral. Whenever it strikes, however, the snake succeeds in predation by handling dextral and sinistral prey in reverse. In contrast, P. iwasakii with little access to sinistrals on small peripheral islands attempts and frequently misses capturing a given sinistral. Prey-handedness recognition should be advantageous for right-handed snail-eating snakes where frequently encountering sinistrals. Under dextral-predation by Pareas snakes, adaptive fixation of a prey population for a reversal gene instantaneously generates a sinistral species because interchiral mating is rarely possible. The novel warning, instead of sheltering, effect of sinistrality benefitting both predators and prey could further accelerate single-gene ecological speciation by left-right reversal. PMID:27046345

  7. Predator pursuit strategies: how do falcons and hawks chase prey?

    NASA Astrophysics Data System (ADS)

    Kane, Suzanne Amador; Zamani, Marjon; Fulton, Andrew; Rosenthal, Lee

    2014-03-01

    This study reports on experiments on falcons, goshawks and red-tailed hawks wearing miniature videocameras mounted on their backs or heads while pursuing flying or ground-based prey. Videos of hunts recorded by the raptors were analyzed to determine apparent prey positions on their visual fields during pursuits. These video data then were interpreted using computer simulations of pursuit steering laws observed in insects and mammals. A comparison of the empirical and modeling data indicates that falcons use cues due to the apparent motion of prey on the falcon's visual field to track and capture flying prey via a form of motion camouflage. The falcons also were found to maintain their prey's image at visual angles consistent with using their shallow fovea. Results for goshawks and red-tailed hawks were analyzed for a comparative study of how pursuits of ground-based prey by accipeters and buteos differ from those used by falcons chasing flying prey. These results should prove relevant for understanding the coevolution of pursuit and evasion, as well as the development of computer models of predation on flocks,and the integration of sensory and locomotion systems in biomimetic robots.

  8. Acoustic mirror effect increases prey detection distance in trawling bats

    NASA Astrophysics Data System (ADS)

    Siemers, Björn M.; Baur, Eric; Schnitzler, Hans-Ulrich

    2005-06-01

    Many different and phylogenetically distant species of bats forage for insects above water bodies and take insects from and close to the surface; the so-called ‘trawling behaviour’. Detection of surface-based prey by echolocation is facilitated by acoustically smooth backgrounds such as water surfaces that reflect sound impinging at an acute angle away from the bat and thereby render a prey object acoustically conspicuous. Previous measurements had shown that the echo amplitude of a target on a smooth surface is higher than that of the same target in mid-air, due to an acoustic mirror effect. In behavioural experiments with three pond bats (Myotis dasycneme), we tested the hypothesis that the maximum distances at which bats can detect prey are larger for prey on smooth surfaces than for the same prey in an airborne situation. We determined the moment of prey detection from a change in echolocation behaviour and measured the detection distance in 3D space from IR-video recordings using stereo-photogrammetry. The bats showed the predicted increase in detection distance for prey on smooth surfaces. The acoustic mirror effect therefore increases search efficiency and contributes to the acoustic advantages encountered by echolocating bats when foraging at low heights above smooth water surfaces. These acoustic advantages may have favoured the repeated evolution of trawling behaviour.

  9. Disentangling mite predator-prey relationships by multiplex PCR.

    PubMed

    Pérez-Sayas, Consuelo; Pina, Tatiana; Gómez-Martínez, María A; Camañes, Gemma; Ibáñez-Gual, María V; Jaques, Josep A; Hurtado, Mónica A

    2015-11-01

    Gut content analysis using molecular techniques can help elucidate predator-prey relationships in situations in which other methodologies are not feasible, such as in the case of trophic interactions between minute species such as mites. We designed species-specific primers for a mite community occurring in Spanish citrus orchards comprising two herbivores, the Tetranychidae Tetranychus urticae and Panonychus citri, and six predatory mites belonging to the Phytoseiidae family; these predatory mites are considered to be these herbivores' main biological control agents. These primers were successfully multiplexed in a single PCR to test the range of predators feeding on each of the two prey species. We estimated prey DNA detectability success over time (DS50), which depended on the predator-prey combination and ranged from 0.2 to 18 h. These values were further used to weight prey detection in field samples to disentangle the predatory role played by the most abundant predators (i.e. Euseius stipulatus and Phytoseiulus persimilis). The corrected predation value for E. stipulatus was significantly higher than for P. persimilis. However, because this 1.5-fold difference was less than that observed regarding their sevenfold difference in abundance, we conclude that P. persimilis is the most effective predator in the system; it preyed on tetranychids almost five times more frequently than E. stipulatus did. The present results demonstrate that molecular tools are appropriate to unravel predator-prey interactions in tiny species such as mites, which include important agricultural pests and their predators. PMID:25824504

  10. Interaction of nemertines and their prey on tidal flats

    NASA Astrophysics Data System (ADS)

    Thiel, Martin; Reise, Karsten

    Two common nemertines of the European Wadden Sea, Lineus viridis and Amphiporus lactifloreus, occur preferentially in clusters of mussels, spread over sedimentary flats in the upper intertidal near the island of Sylt. The heteronemertine L. viridis preys mainly on the polychaete Nereis diversicolor. The hoplonemertine A. lactifloreus feeds almost exclusively on the amphipod Gammarus locusta. Abundance of both predators and their respective prey in the field showed inverse relationships. Experimentally increased numbers of L. viridis in clusters of mussels caused a gradual decrease of nereid abundance in the sediment underneath over a period of 1 month, suggesting that losses of individuals were caused by prey capture. Experimentally increased numbers of A. lactifloreus were followed by an escape response of gammarids from clusters of mussels within 2 d. In aquaria, both prey species exhibited prolonged swimming activity when their respective predators lurked at the bottom. We conclude that escape behaviour in N. diversicolor may be only effective during its migrant phases, while G. locusta is permanently on the alert to avoid encounters with its predator. This refuging behaviour in response to endobenthic predators has strong implications on prey distribution, while the actual consumption of prey may be relatively modest. Enclosure experiments in the field and in aquaria lead to overestimates of prey capture when refuging behaviour is not accounted for.

  11. Predator-prey pursuit-evasion games in structurally complex environments.

    PubMed

    Morice, Sylvie; Pincebourde, Sylvain; Darboux, Frédéric; Kaiser, Wilfried; Casas, Jérôme

    2013-11-01

    Pursuit and evasion behaviors in many predator-prey encounters occur in a geometrically structured environment. The physical structures in the environment impose strong constraints on the perception and behavioral responses of both antagonists. Nevertheless, no experimental or theoretical study has tackled the issue of quantifying the role of the habitat's architecture on the joint trajectories during a predator-prey encounter. In this study, we report the influence of microtopography of forest leaf litter on the pursuit-evasion trajectories of wolf spiders Pardosa sp. attacking the wood cricket Nemobius sylvestris. Fourteen intact leaf litter samples of 1 m × 0.5 m were extracted from an oak-beech forest floor in summer and winter, with later samples having the most recently fallen leaves. Elevation was mapped at a spatial resolution of 0.5 mm using a laser scanner. Litter structuring patterns were identified by height transects and experimental semi-variograms. Detailed analysis of all visible leaf-fragments of one sample enabled us to relate the observed statistical patterns to the underlying geometry of individual elements. Video recording of pursuit-evasion sequences in arenas with flat paper or leaf litter enabled us to estimate attack and fleeing distances as a function of substrate. The compaction index, the length of contiguous flat surfaces, and the experimental variograms showed that the leaf litter was smoother in summer than in winter. Thus, weathering as well as biotic activities compacted and flattened the litter over time. We found good agreement between the size of the structuring unit of leaf litter and the distance over which attack and escape behaviors both were initiated (both ∼3 cm). There was a four-fold topographical effect on pursuit-escape sequences; compared with a flat surface, leaf litter (1) greatly reduced the likelihood of launching a pursuit, (2) reduced pursuit and escape distances by half, (3) put prey and predator on par in

  12. Predator size, prey size and threshold food densities of diving ducks: does a common prey base support fewer large animals?

    PubMed

    Richman, Samantha E; Lovvorn, James R

    2009-09-01

    1. Allometry predicts that a given habitat area or common prey biomass supports fewer numbers of larger than smaller predators; however, birds from related taxa or the same feeding guild often deviate from this pattern. In particular, foraging costs of birds may differ among locomotor modes, while intake rates vary with accessibility, handling times and energy content of different-sized prey. Such mechanisms might affect threshold prey densities needed for energy balance, and thus relative numbers of different-sized predators in habitats with varying prey patches. 2. We compared the foraging profitability (energy gain minus cost) of two diving ducks: smaller lesser scaup (Aythya affinis, 450-1090 g) and larger white-winged scoters (Melanitta fusca, 950-1800 g). Calculations were based on past measurements of dive costs with respirometry, and of intake rates of a common bivalve prey ranging in size, energy content and burial depth in sediments. 3. For scaup feeding on small prey <12 mm long, all clams buried deeper than 5 cm were unprofitable at realistic prey densities. For clams buried in the top 5 cm, the profitability threshold decreased from 216 to 34 clams m(-2) as energy content increased from 50 to 300 J clam(-1). 4. For larger scoters feeding on larger prey 18-24 mm long, foraging was profitable for clams buried deeper than 5 cm, with a threshold density of 147 m(-2) for clams containing 380 J clam(-1). For clams <5 cm deep, the threshold density decreased from 86 to 36 clams m(-2) as energy content increased from 380 to 850 J clam(-1). If scoters decreased dive costs by swimming with wings as well as feet (not an option for scaup), threshold prey densities were 11-12% lower. 5. Our results show that threshold densities of total prey numbers for different-sized ducks depend on prey size structure and depth in the sediments. Thus, heterogeneity in disturbance regimes and prey population dynamics can create a mosaic of patches favouring large or small

  13. Echolocating Bats Use a Nearly Time-Optimal Strategy to Intercept Prey

    PubMed Central

    Horiuchi, Timothy K; Krishnaprasad, P. S; Moss, Cynthia F

    2006-01-01

    Acquisition of food in many animal species depends on the pursuit and capture of moving prey. Among modern humans, the pursuit and interception of moving targets plays a central role in a variety of sports, such as tennis, football, Frisbee, and baseball. Studies of target pursuit in animals, ranging from dragonflies to fish and dogs to humans, have suggested that they all use a constant bearing (CB) strategy to pursue prey or other moving targets. CB is best known as the interception strategy employed by baseball outfielders to catch ballistic fly balls. CB is a time-optimal solution to catch targets moving along a straight line, or in a predictable fashion—such as a ballistic baseball, or a piece of food sinking in water. Many animals, however, have to capture prey that may make evasive and unpredictable maneuvers. Is CB an optimum solution to pursuing erratically moving targets? Do animals faced with such erratic prey also use CB? In this paper, we address these questions by studying prey capture in an insectivorous echolocating bat. Echolocating bats rely on sonar to pursue and capture flying insects. The bat's prey may emerge from foliage for a brief time, fly in erratic three-dimensional paths before returning to cover. Bats typically take less than one second to detect, localize and capture such insects. We used high speed stereo infra-red videography to study the three dimensional flight paths of the big brown bat, Eptesicus fuscus, as it chased erratically moving insects in a dark laboratory flight room. We quantified the bat's complex pursuit trajectories using a simple delay differential equation. Our analysis of the pursuit trajectories suggests that bats use a constant absolute target direction strategy during pursuit. We show mathematically that, unlike CB, this approach minimizes the time it takes for a pursuer to intercept an unpredictably moving target. Interestingly, the bat's behavior is similar to the interception strategy implemented in some

  14. Echolocating bats use a nearly time-optimal strategy to intercept prey.

    PubMed

    Ghose, Kaushik; Horiuchi, Timothy K; Krishnaprasad, P S; Moss, Cynthia F

    2006-05-01

    Acquisition of food in many animal species depends on the pursuit and capture of moving prey. Among modern humans, the pursuit and interception of moving targets plays a central role in a variety of sports, such as tennis, football, Frisbee, and baseball. Studies of target pursuit in animals, ranging from dragonflies to fish and dogs to humans, have suggested that they all use a constant bearing (CB) strategy to pursue prey or other moving targets. CB is best known as the interception strategy employed by baseball outfielders to catch ballistic fly balls. CB is a time-optimal solution to catch targets moving along a straight line, or in a predictable fashion--such as a ballistic baseball, or a piece of food sinking in water. Many animals, however, have to capture prey that may make evasive and unpredictable maneuvers. Is CB an optimum solution to pursuing erratically moving targets? Do animals faced with such erratic prey also use CB? In this paper, we address these questions by studying prey capture in an insectivorous echolocating bat. Echolocating bats rely on sonar to pursue and capture flying insects. The bat's prey may emerge from foliage for a brief time, fly in erratic three-dimensional paths before returning to cover. Bats typically take less than one second to detect, localize and capture such insects. We used high speed stereo infra-red videography to study the three dimensional flight paths of the big brown bat, Eptesicus fuscus, as it chased erratically moving insects in a dark laboratory flight room. We quantified the bat's complex pursuit trajectories using a simple delay differential equation. Our analysis of the pursuit trajectories suggests that bats use a constant absolute target direction strategy during pursuit. We show mathematically that, unlike CB, this approach minimizes the time it takes for a pursuer to intercept an unpredictably moving target. Interestingly, the bat's behavior is similar to the interception strategy implemented in some

  15. Flexibility in assessment of prey cues: frog-eating bats and frog calls

    PubMed Central

    Page, Rachel A; Ryan, Michael J

    2005-01-01

    Predators use cues associated with their prey to assess prey quality and to avoid consuming poisonous prey. Considerable attention has been given to predators' use of aposematic cues to assess prey quality, but little is known about predators that eavesdrop on prey cues that are not intended for them. Here we investigate the prey-cue/prey-quality associations of a predator that eavesdrops on the sexual advertisement signals of its prey. Stability is expected in prey-cue/prey-quality associations when mistakes in prey assessment are lethal. Conversely, flexibility is possible when mistakes are less costly. Predators that must respond to temporal and spatial fluctuations in prey availability should be more flexible in their assessment of prey quality. Given these predictions, we examined flexibility in the ability of wild-caught bats to reverse prey-cue/prey-quality associations for a preferred prey and a poisonous one. We found that the predatory bat, Trachops cirrhosus, has a heretofore undescribed ability to reverse its evaluations of the cues that signal preferred prey. PMID:15888417

  16. Sensorimotor model of bat echolocation and prey capture.

    PubMed

    Kuc, R

    1994-10-01

    A model of the bat sensorimotor system is developed using acoustics, signal processing, and control theory to illustrate the fundamental issues in accomplishing prey capture with echolocation. This model indicates that successful nonpredictive tracking of an ideal prey can be accomplished with a very simple system. Circular apertures approximate the mouth and ears for deriving acoustic beam patterns, using the big brown bat Eptesicus fuscus as a model. Fundamental and overtone frequency components in the emissions allow two simultaneous acoustic beams to be defined. A pair of nonlinear, time-variable, sampled-data controllers alter the bat's heading by applying yaw and pitch heading corrections. The yaw correction attempts to position the prey in the midsagittal plane by nulling the interaural intensity difference of the fundamental component. The pitch correction compares the intensities of the overtone and fundamental components and acts to null their difference. By initiating pitch correction when the overtone intensity first exceeds that of the fundamental, the ambiguity problem is solved and the prey is directed to the capture region. Simulations of passive prey capture indicate that the capture probability decreases as the prey speed increases. Both quick and sluggish prey are considered, with sluggish prey found to be caught with slightly better efficiency. The magnitude of the prey's lateral motion just prior to capture is observed to be an important factor determining capture. The presence of a blind stage is considered, during which the interference of the emission with the echo is assumed to disrupt any sonar information. The presence of such a blind stage is found to have negligible effect on capture efficiency. PMID:7963018

  17. An Oral History of First-Generation Leaders in Education of Children with Emotional/Behavioral Disorders, Part 3: The Future

    ERIC Educational Resources Information Center

    Kaff, Marilyn S.; Zabel, Robert; Teagarden, Jim

    2011-01-01

    In this the third part of an oral history of education of students with emotional and behavioral disorders, 15 first-generation leaders were asked to forecast the future of the field and to advise persons entering the profession. Their videotaped conversations were transcribed, were analyzed, and are reported here together with some discussion of…

  18. Fast sensory–motor reactions in echolocating bats to sudden changes during the final buzz and prey intercept

    PubMed Central

    Geberl, Cornelia; Brinkløv, Signe; Wiegrebe, Lutz; Surlykke, Annemarie

    2015-01-01

    Echolocation is an active sense enabling bats and toothed whales to orient in darkness through echo returns from their ultrasonic signals. Immediately before prey capture, both bats and whales emit a buzz with such high emission rates (≥180 Hz) and overall duration so short that its functional significance remains an enigma. To investigate sensory–motor control during the buzz of the insectivorous bat Myotis daubentonii, we removed prey, suspended in air or on water, before expected capture. The bats responded by shortening their echolocation buzz gradually; the earlier prey was removed down to approximately 100 ms (30 cm) before expected capture, after which the full buzz sequence was emitted both in air and over water. Bats trawling over water also performed the full capture behavior, but in-air capture motions were aborted, even at very late prey removals (<20 ms = 6 cm before expected contact). Thus, neither the buzz nor capture movements are stereotypical, but dynamically adapted based on sensory feedback. The results indicate that echolocation is controlled mainly by acoustic feedback, whereas capture movements are adjusted according to both acoustic and somatosensory feedback, suggesting separate (but coordinated) central motor control of the two behaviors based on multimodal input. Bat echolocation, especially the terminal buzz, provides a unique window to extremely fast decision processes in response to sensory feedback and modulation through attention in a naturally behaving animal. PMID:25775538

  19. Fast sensory-motor reactions in echolocating bats to sudden changes during the final buzz and prey intercept.

    PubMed

    Geberl, Cornelia; Brinkløv, Signe; Wiegrebe, Lutz; Surlykke, Annemarie

    2015-03-31

    Echolocation is an active sense enabling bats and toothed whales to orient in darkness through echo returns from their ultrasonic signals. Immediately before prey capture, both bats and whales emit a buzz with such high emission rates (≥ 180 Hz) and overall duration so short that its functional significance remains an enigma. To investigate sensory-motor control during the buzz of the insectivorous bat Myotis daubentonii, we removed prey, suspended in air or on water, before expected capture. The bats responded by shortening their echolocation buzz gradually; the earlier prey was removed down to approximately 100 ms (30 cm) before expected capture, after which the full buzz sequence was emitted both in air and over water. Bats trawling over water also performed the full capture behavior, but in-air capture motions were aborted, even at very late prey removals (<20 ms = 6 cm before expected contact). Thus, neither the buzz nor capture movements are stereotypical, but dynamically adapted based on sensory feedback. The results indicate that echolocation is controlled mainly by acoustic feedback, whereas capture movements are adjusted according to both acoustic and somatosensory feedback, suggesting separate (but coordinated) central motor control of the two behaviors based on multimodal input. Bat echolocation, especially the terminal buzz, provides a unique window to extremely fast decision processes in response to sensory feedback and modulation through attention in a naturally behaving animal. PMID:25775538

  20. Response of brown treesnakes to reduction of their rodent prey

    USGS Publications Warehouse

    Gragg, J.E.; Rodda, G.H.; Savidge, J.A.; White, Gary C.; Dean-Bradley, K.; Ellingson, A.R.

    2007-01-01

    Trapping brown treesnakes (Boiga irregularis; BTS) with live-mouse (Mus domesticus) lures is the principal control technique for this invasive species on Guam. Lure-based trapping is also used on other islands as a precaution against undetected arrivals and in response to verified BTS sightings. However, the effectiveness of lure-based trapping on other islands is questionable, as it has yielded no BTS despite other evidence of their presence. Some evidence suggests that high rodent numbers may interfere with BTS control. To test the relationship between rodent abundance and snake trappability, we conducted a controlled, replicated field experiment incorporating a rodenticide treatment during a BTS mark-recapture study. Using open population modeling in Program MARK, we estimated BTS apparent survival and recapture probabilities. Rodent reduction increased BTS recapture probabilities by 52-65% in 2002 and 22-36% in 2003, and it decreased apparent survival by <1% both years. This appears to be the first published instance of manipulating wild prey to influence snake behavior. Rodent reduction may enhance detection and control of BTS with traps on Guam and other islands. It may also amplify the effectiveness of oral toxicants against BTS.

  1. Prey-producing predators: the ecology of human intensification.

    PubMed

    Efferson, Charles

    2008-01-01

    Economic growth theory and theoretical ecology represent independent traditions of modeling aggregate consumer-resource systems. Both focus on different but equally important forces underlying the dynamics of human societies. Though the two traditions have unknowingly converged in some ways, they each have curious conventions from the perspective of the other. These conventions are reviewed, and two separate modeling frameworks that integrate the two traditions in a simple and straightforward fashion are developed and analyzed. The resulting models represent a consumer species (e.g. humans) that both produces and consumes its resources and then reproduces biologically according to the consumption of its resources. Depending on the balance between production, consumption, and reproduction, the models can exhibit stagnant behavior, like some predator-prey models, or growth, like many mutualism and economic growth models. When growth occurs, in the long term it takes one of two forms. Either resources per capita grow and the human population size converges to a constant, which may be zero, or resources per capita converge to a constant and the human population grows. The difference depends on initial conditions and the particular mix of biological conditions and human technology. PMID:18157927

  2. The Present Projects Past Behavior into the Future while the Past Projects Attitudes into the Future: How Verb Tense Moderates Predictors of Drinking Intentions

    PubMed Central

    Carrera, Pilar; Muñoz, Dolores; Caballero, Amparo; Fernández, Itziar; Albarracín, Dolores

    2013-01-01

    Three studies examined how the use of the present versus the past tense in recalling a past experience influences behavioral intentions. Experiment 1 revealed a stronger influence of past behaviors on drinking intentions when participants self-reported an episode of excessive drinking using the present tense. Correspondingly, there was a stronger influence of attitudes towards excessive drinking when participants self-reported the episode in the past tense. Experiments 2 and 3 liked this effect to changes in construal level (Liberman, Trope, & Stephan, 2007; Trope & Liberman, 2003), with the present tense being similar to a concrete construal level and the past tense being similar to an abstract construal level. PMID:23606757

  3. Characterization of multiple spiral wave dynamics as a stochastic predator-prey system

    NASA Astrophysics Data System (ADS)

    Otani, Niels F.; Mo, Alisa; Mannava, Sandeep; Fenton, Flavio H.; Cherry, Elizabeth M.; Luther, Stefan; Gilmour, Robert F., Jr.

    2008-08-01

    A perspective on systems containing many action potential waves that, individually, are prone to spiral wave breakup is proposed. The perspective is based on two quantities, “predator” and “prey,” which we define as the fraction of the system in the excited state and in the excitable but unexcited state, respectively. These quantities exhibited a number of properties in both simulations and fibrillating canine cardiac tissue that were found to be consistent with a proposed theory that assumes the existence of regions we call “domains of influence,” each of which is associated with the activity of one action potential wave. The properties include (i) a propensity to rotate in phase space in the same sense as would be predicted by the standard Volterra-Lotka predator-prey equations, (ii) temporal behavior ranging from near periodic oscillation at a frequency close to the spiral wave rotation frequency (“type-1” behavior) to more complex oscillatory behavior whose power spectrum is composed of a range of frequencies both above and, especially, below the spiral wave rotation frequency (“type-2” behavior), and (iii) a strong positive correlation between the periods and amplitudes of the oscillations of these quantities. In particular, a rapid measure of the amplitude was found to scale consistently as the square root of the period in data taken from both simulations and optical mapping experiments. Global quantities such as predator and prey thus appear to be useful in the study of multiple spiral wave systems, facilitating the posing of new questions, which in turn may help to provide greater understanding of clinically important phenomena such as ventricular fibrillation.

  4. Characterization of multiple spiral wave dynamics as a stochastic predator-prey system.

    PubMed

    Otani, Niels F; Mo, Alisa; Mannava, Sandeep; Fenton, Flavio H; Cherry, Elizabeth M; Luther, Stefan; Gilmour, Robert F

    2008-08-01

    A perspective on systems containing many action potential waves that, individually, are prone to spiral wave breakup is proposed. The perspective is based on two quantities, "predator" and "prey," which we define as the fraction of the system in the excited state and in the excitable but unexcited state, respectively. These quantities exhibited a number of properties in both simulations and fibrillating canine cardiac tissue that were found to be consistent with a proposed theory that assumes the existence of regions we call "domains of influence," each of which is associated with the activity of one action potential wave. The properties include (i) a propensity to rotate in phase space in the same sense as would be predicted by the standard Volterra-Lotka predator-prey equations, (ii) temporal behavior ranging from near periodic oscillation at a frequency close to the spiral wave rotation frequency ("type-1" behavior) to more complex oscillatory behavior whose power spectrum is composed of a range of frequencies both above and, especially, below the spiral wave rotation frequency ("type-2" behavior), and (iii) a strong positive correlation between the periods and amplitudes of the oscillations of these quantities. In particular, a rapid measure of the amplitude was found to scale consistently as the square root of the period in data taken from both simulations and optical mapping experiments. Global quantities such as predator and prey thus appear to be useful in the study of multiple spiral wave systems, facilitating the posing of new questions, which in turn may help to provide greater understanding of clinically important phenomena such as ventricular fibrillation. PMID:18850871

  5. Understanding spatial distributions: negative density-dependence in prey causes predators to trade-off prey quantity with quality.

    PubMed

    Bijleveld, Allert I; MacCurdy, Robert B; Chan, Ying-Chi; Penning, Emma; Gabrielson, Rich M; Cluderay, John; Spaulding, Eric L; Dekinga, Anne; Holthuijsen, Sander; ten Horn, Job; Brugge, Maarten; van Gils, Jan A; Winkler, David W; Piersma, Theunis

    2016-04-13

    Negative density-dependence is generally studied within a single trophic level, thereby neglecting its effect on higher trophic levels. The 'functional response' couples a predator's intake rate to prey density. Most widespread is a type II functional response, where intake rate increases asymptotically with prey density; this predicts the highest predator densities at the highest prey densities. In one of the most stringent tests of this generality to date, we measured density and quality of bivalve prey (edible cockles Cerastoderma edule) across 50 km² of mudflat, and simultaneously, with a novel time-of-arrival methodology, tracked their avian predators (red knots Calidris canutus). Because of negative density-dependence in the individual quality of cockles, the predicted energy intake rates of red knots declined at high prey densities (a type IV, rather than a type II functional response). Resource-selection modelling revealed that red knots indeed selected areas of intermediate cockle densities where energy intake rates were maximized given their phenotype-specific digestive constraints (as indicated by gizzard mass). Because negative density-dependence is common, we question the current consensus and suggest that predators commonly maximize their energy intake rates at intermediate prey densities. Prey density alone may thus poorly predict intake rates, carrying capacity and spatial distributions of predators. PMID:27053747

  6. Sensory exploitation of prey: manipulation of the initial direction of prey escapes by a conspicuous "rare enemy".

    PubMed

    Jabłonski, P G

    2001-05-22

    The painted redstart (Myioborus pictus) represents a group of non-cryptic predators, the flush pursuers, who visually trigger prey escapes by spreading and pivoting their conspicuously patterned tails and wings. The prey are then chased in aerial pursuits. Such an exploitation of prey may be possible because the predation risk from redstarts is smaller than that from the predatory guild of insectivores and their neural pathways are adapted to helping prey avoid common predators rather than "rare enemies". I propose that the pivoting movements of flush pursuers direct insect escapes across the central field of vision of a predator, where it is easier to track and intercept the prey. Eighty per cent of chases by wild redstarts were in a direction suggesting that prey were entering the birds' area of stereoscopic vision. The redstart's fanned and raised tail creates a stronger visual stimulus than a redstart's head. Flies escaped away from the section of the fly's field of vision in which the model's tail was located and towards the area where the predator's stereoscopic vision is likely to be located, in front of a bird's forehead. The experiments suggested that redstarts may not only exploit the sensitivity of typical neural escape pathways, which are non-directionally sensitive, but that they may also exploit the sensitivity of some directionally sensitive neural pathways in prey. PMID:11375085

  7. Cell-cycle progress in obligate predatory bacteria is dependent upon sequential sensing of prey recognition and prey quality cues

    PubMed Central

    Rotem, Or; Pasternak, Zohar; Shimoni, Eyal; Belausov, Eduard; Porat, Ziv; Pietrokovski, Shmuel; Jurkevitch, Edouard

    2015-01-01

    Predators feed on prey to acquire the nutrients necessary to sustain their survival, growth, and replication. In Bdellovibrio bacteriovorus, an obligate predator of Gram-negative bacteria, cell growth and replication are tied to a shift from a motile, free-living phase of search and attack to a sessile, intracellular phase of growth and replication during which a single prey cell is consumed. Engagement and sustenance of growth are achieved through the sensing of two unidentified prey-derived cues. We developed a novel ex vivo cultivation system for B. bacteriovorus composed of prey ghost cells that are recognized and invaded by the predator. By manipulating their content, we demonstrated that an early cue is located in the prey envelope and a late cue is found within the prey soluble fraction. These spatially and temporally separated cues elicit discrete and combinatory regulatory effects on gene transcription. Together, they delimit a poorly characterized transitory phase between the attack phase and the growth phase, during which the bdelloplast (the invaded prey cell) is constructed. This transitory phase constitutes a checkpoint in which the late cue presumably acts as a determinant of the prey’s nutritional value before the predator commits. These regulatory adaptations to a unique bacterial lifestyle have not been reported previously. PMID:26487679

  8. Sensory challenges for trawling bats: Finding transient prey on water surfaces.

    PubMed

    Übernickel, Kirstin; Simon, Ralph; Kalko, Elisabeth K V; Tschapka, Marco

    2016-04-01

    Bats are able to identify obstacles and prey objects based exclusively on acoustic information acquired via echolocation. To assess the echo information potentially available to the trawling bat Noctilio leporinus, prey objects were ensonified with artificial bat calls and deduced echo target strengths (TS) of the reflected signals. The artificial calls consisted either of constant frequency (CF) or frequency modulated (FM) sounds. Detection distances were calculated for call intensities of N. leporinus emitted in the field and in confined space. Measurements of a transient target consisting of a brief water splash and subsequently expanding water ripples revealed that concentrically expanding water ripples can provide sufficiently loud echoes to be detected by trawling bats. Experiments with stationary targets revealed differences in TS depending on the type of signal used (CF or FM). A calculated maximum detection distance between 4.5 and 13.7 m for all measured targets indicates that prey detection in this very loud calling species occurs much earlier than suggested by estimations based on modifications in echolocation or flight behavior. PMID:27106338

  9. Talking helps: evolving communicating agents for the predator-prey pursuit problem.

    PubMed

    Jim, K C; Giles, C L

    2000-01-01

    We analyze a general model of multi-agent communication in which all agents communicate simultaneously to a message board. A genetic algorithm is used to evolve multi-agent languages for the predator agents in a version of the predator-prey pursuit problem. We show that the resulting behavior of the communicating multi-agent system is equivalent to that of a Mealy finite state machine whose states are determined by the agents' usage of the evolved language. Simulations show that the evolution of a communication language improves the performance of the predators. Increasing the language size (and thus increasing the number of possible states in the Mealy machine) improves the performance even further. Furthermore, the evolved communicating predators perform significantly better than all previous work on similar prey. We introduce a method for incrementally increasing the language size, which results in an effective coarse-to-fine search that significantly reduces the evolution time required to find a solution. We present some observations on the effects of language size, experimental setup, and prey difficulty on the evolved Mealy machines. In particular, we observe that the start state is often revisited, and incrementally increasing the language size results in smaller Mealy machines. Finally, a simple rule is derived that provides a pessimistic estimate on the minimum language size that should be used for any multi-agent problem. PMID:11224918

  10. Fluctuation-induced patterns and rapid evolution in predator-prey ecosystems

    NASA Astrophysics Data System (ADS)

    Goldenfeld, Nigel

    2014-03-01

    Predator-prey ecosystems exhibit noisy, persistent cycles that cannot be described by intuitive population-level differential equations such as the Lotka-Volterra equations. Traditionally this paradox has been met by including additional nonlinearities such as predator satiation to force limit cycle behavior. Over the last few years, it has been realized that individual-level descriptions, combined with systematic perturbation techniques can reproduce the key features of such systems in a minimal way, without requiring many additional assumptions or fine tunings. Here I review work in this area that uses these techniques to treat spatial patterns and the phenomenon of rapidly evolving prey sub-populations. In the latter case, I show how stochastic individual-level models reproduce the key features observed in chemostats and in the wild, including anomalous phase shifts between predator and prey species, evolutionary cycles and cryptic cycles. This work shows that stochastic individual-level models naturally describe systems where evolutionary time scales surprisingly match ecosystem time scales.

  11. Niche overlap, threshold food densities, and limits to prey depletion for a diving duck assemblage in an estuarine bay

    USGS Publications Warehouse

    Lovvorn, James R.; De La Cruz, Susan; Takekawa, John Y.; Shaskey, Laura E.; Richman, Samantha E.

    2013-01-01

    Planning for marine conservation often requires estimates of the amount of habitat needed to support assemblages of interacting species. During winter in subtidal San Pablo Bay, California, the 3 main diving duck species are lesser scaup Aythya affinis (LESC), greater scaup A. marila (GRSC), and surf scoter Melanitta perspicillata (SUSC), which all feed almost entirely on the bivalve Corbula amurensis. Decreased body mass and fat, increased foraging effort, and major departures of these birds appeared to result from food limitation. Broad overlap in prey size, water depth, and location suggested that the 3 species responded similarly to availability of the same prey. However, an energetics model that accounts for differing body size, locomotor mode, and dive behavior indicated that each species will become limited at different stages of prey depletion in the order SUSC, then GRSC, then LESC. Depending on year, 35 to 66% of the energy in Corbula standing stocks was below estimated threshold densities for profitable foraging. Ectothermic predators, especially flounders and sturgeons, could reduce excess carrying capacity for different duck species by 4 to 10%. A substantial quantity of prey above profitability thresholds was not exploited before most ducks left San Pablo Bay. Such pre-depletion departure has been attributed in other taxa to foraging aggression. However, in these diving ducks that showed no overt aggression, this pattern may result from high costs of locating all adequate prey patches, resulting reliance on existing flocks to find food, and propensity to stay near dense flocks to avoid avian predation. For interacting species assemblages, modeling profitability thresholds can indicate the species most vulnerable to food declines. However, estimates of total habitat needed require better understanding of factors affecting the amount of prey above thresholds that is not depleted before the predators move elsewhere.

  12. Reproducibility and relevance of future behavioral sciences should benefit from a cross fertilization of past recommendations and today's technology: "Back to the future".

    PubMed

    Spruijt, Berry M; Peters, Suzanne M; de Heer, Raymond C; Pothuizen, Helen H J; van der Harst, Johanneke E

    2014-08-30

    Thanks to the discovery of novel technologies and sophisticated analysis tools we can now 'see' molecules, genes and even patterns of gene expression, which have resulted in major advances in many areas of biology. Recently, similar technologies have been developed for behavioral studies. However, the wide implementation of such technological progress in behavioral research remains behind, as if there are inhibiting factors for accepting and adopting available innovations. The methods of the majority of studies measuring and interpreting behavior of laboratory animals seem to have frozen in time somewhere in the last century. As an example of the so-called classical tests, we will present the history and shortcomings of one of the most frequently used tests, the open field. Similar objections and critical remarks, however, can be made with regard to the elevated plus maze, light-dark box, various other mazes, object recognition tests, etc. Possible solutions and recommendations on how progress in behavioral neuroscience can be achieved and accelerated will be discussed in the second part of this review. PMID:24632384

  13. Assessing the Role of Livestock in Big Cat Prey Choice Using Spatiotemporal Availability Patterns.

    PubMed

    Ghoddousi, Arash; Soofi, Mahmood; Kh Hamidi, Amirhossein; Lumetsberger, Tanja; Egli, Lukas; Khorozyan, Igor; Kiabi, Bahram H; Waltert, Matthias

    2016-01-01

    Livestock is represented in big cat diets throughout the world. Husbandry approaches aim to reduce depredation, which may influence patterns of prey choice, but whether felids have a preference for livestock or not often remains unclear as most studies ignore livestock availability. We assessed prey choice of the endangered Persian leopard (Panthera pardus saxicolor) in Golestan National Park, Iran, where conflict over livestock depredation occurs. We analyzed leopard diet (77 scats) and assessed wild and domestic prey abundance by line transect sampling (186 km), camera-trapping (2777 camera days), double-observer point-counts (64 scans) and questionnaire surveys (136 respondents). Based on interviews with 18 shepherds, we estimated monthly grazing time outside six villages with 96 conflict cases to obtain a small livestock (domestic sheep and goat) availability coefficient. Using this coefficient, which ranged between 0.40 and 0.63 for different villages, we estimated the numbers of sheep and goats available to leopard depredation. Leopard diet consisted mainly of wild boar (Sus scrofa) (50.2% biomass consumed), but bezoar goat (Capra aegagrus) was the most preferred prey species (Ij = 0.73), whereas sheep and goats were avoided (Ij = -0.54). When absolute sheep and goat numbers (~11250) were used instead of the corrected ones (~6392), avoidance of small livestock appeared to be even stronger (Ij = -0.71). We suggest that future assessments of livestock choice by felids should incorporate such case-specific corrections for spatiotemporal patterns of availability, which may vary with husbandry methods. Such an approach increases our understanding of human-felid conflict dynamics and the role of livestock in felid diets. PMID:27064680

  14. Assessing the Role of Livestock in Big Cat Prey Choice Using Spatiotemporal Availability Patterns

    PubMed Central

    Ghoddousi, Arash; Soofi, Mahmood; Kh. Hamidi, Amirhossein; Lumetsberger, Tanja; Egli, Lukas; Khorozyan, Igor; Kiabi, Bahram H.; Waltert, Matthias

    2016-01-01

    Livestock is represented in big cat diets throughout the world. Husbandry approaches aim to reduce depredation, which may influence patterns of prey choice, but whether felids have a preference for livestock or not often remains unclear as most studies ignore livestock availability. We assessed prey choice of the endangered Persian leopard (Panthera pardus saxicolor) in Golestan National Park, Iran, where conflict over livestock depredation occurs. We analyzed leopard diet (77 scats) and assessed wild and domestic prey abundance by line transect sampling (186 km), camera-trapping (2777 camera days), double-observer point-counts (64 scans) and questionnaire surveys (136 respondents). Based on interviews with 18 shepherds, we estimated monthly grazing time outside six villages with 96 conflict cases to obtain a small livestock (domestic sheep and goat) availability coefficient. Using this coefficient, which ranged between 0.40 and 0.63 for different villages, we estimated the numbers of sheep and goats available to leopard depredation. Leopard diet consisted mainly of wild boar (Sus scrofa) (50.2% biomass consumed), but bezoar goat (Capra aegagrus) was the most preferred prey species (Ij = 0.73), whereas sheep and goats were avoided (Ij = -0.54). When absolute sheep and goat numbers (~11250) were used instead of the corrected ones (~6392), avoidance of small livestock appeared to be even stronger (Ij = -0.71). We suggest that future assessments of livestock choice by felids should incorporate such case-specific corrections for spatiotemporal patterns of availability, which may vary with husbandry methods. Such an approach increases our understanding of human-felid conflict dynamics and the role of livestock in felid diets. PMID:27064680

  15. Dynamics of the echolocation beam during prey pursuit in aerial hawking bats

    PubMed Central

    Jakobsen, Lasse; Olsen, Mads Nedergaard; Surlykke, Annemarie

    2015-01-01

    In the evolutionary arms race between prey and predator, measures and countermeasures continuously evolve to increase survival on both sides. Bats and moths are prime examples. When exposed to intense ultrasound, eared moths perform dramatic escape behaviors. Vespertilionid and rhinolophid bats broaden their echolocation beam in the final stage of pursuit, presumably as a countermeasure to keep evading moths within their “acoustic field of view.” In this study, we investigated if dynamic beam broadening is a general property of echolocation when catching moving prey. We recorded three species of emballonurid bats, Saccopteryx bilineata, Saccopteryx leptura, and Rhynchonycteris naso, catching airborne insects in the field. The study shows that S. bilineata and S. leptura maintain a constant beam shape during the entire prey pursuit, whereas R. naso broadens the beam by lowering the peak call frequency from 100 kHz during search and approach to 67 kHz in the buzz. Surprisingly, both Saccopteryx bats emit calls with very high energy throughout the pursuit, up to 60 times more than R. naso and Myotis daubentonii (a similar sized vespertilionid), providing them with as much, or more, peripheral “vision” than the vespertilionids, but ensonifying objects far ahead suggesting more clutter. Thus, beam broadening is not a fundamental property of the echolocation system. However, based on the results, we hypothesize that increased peripheral detection is crucial to all aerial hawking bats in the final stages of prey pursuit and speculate that beam broadening is a feature characterizing more advanced echolocation. PMID:26080398

  16. Trophic relay and prey switching - A stomach contents and calorimetric investigation of an ambassid fish and their saltmarsh prey

    NASA Astrophysics Data System (ADS)

    McPhee, Jack J.; Platell, Margaret E.; Schreider, Maria J.

    2015-12-01

    Trophic relay is an ecological model that involves the movement of biomass and energy from vegetation, such as saltmarshes, within estuaries to the open sea via a series of predator-prey relationships. Any potential for trophic relay is therefore affected by water movements within an estuary and by the ability of a predator to "switch" prey in response to fluctuating abundances of those prey. Saltmarsh-dwelling grapsid crabs, which feed on saltmarsh-derived detritus and microphytobenthos, release zoeae into ebbing tides that inundate saltmarshes during spring-tide cycles within tidally-dominated estuaries, such as Brisbane Water Estuary, therefore providing an opportunity to examine whether prey-switching and/or trophic relay may occur in fish that feed on those zoeae (such as the highly abundant estuarine ambassid, Ambassis jacksoniensis). This model was examined by sampling A. jacksoniensis near saltmarshes in a large, temperate south-eastern Australian estuary during flood and ebb tides on days of saltmarsh inundation and non-inundation over four spring-tide events in 2012. Stomach fullnesses of A. jacksoniensis were generally highest during ebb tides on days of saltmarsh inundation, implying that feeding was most marked at these times. Caridean decapods dominated diets during flood tides and on days of no saltmarsh inundation, while crab zoeae dominated diets during ebb tides and on days of inundation, suggesting that, when saltmarsh-derived zoeae became abundant, A. jacksoniensis switched to feeding on those prey. Three potential zooplankton prey (calanoid copepods, caridean decapods and crab zoeae) did not differ calorimetrically, indicating that switching of prey by A. jacksoniensis is not directly related to their preying on energetically greater prey, but reflects opportunistic feeding on more abundant and/or less elusive prey. As A. jacksoniensis is able to switch prey from estuarine caridean decapods to saltmarsh-derived crab zoeae, this very abundant

  17. Colour Polymorphism Protects Prey Individuals and Populations Against Predation

    PubMed Central

    Karpestam, Einat; Merilaita, Sami; Forsman, Anders

    2016-01-01

    Colour pattern polymorphism in animals can influence and be influenced by interactions between predators and prey. However, few studies have examined whether polymorphism is adaptive, and there is no evidence that the co-occurrence of two or more natural prey colour variants can increase survival of populations. Here we show that visual predators that exploit polymorphic prey suffer from reduced performance, and further provide rare evidence in support of the hypothesis that prey colour polymorphism may afford protection against predators for both individuals and populations. This protective effect provides a probable explanation for the longstanding, evolutionary puzzle of the existence of colour polymorphisms. We also propose that this protective effect can provide an adaptive explanation for search image formation in predators rather than search image formation explaining polymorphism. PMID:26902799

  18. Effects of random habitat destruction in a predator prey model

    NASA Astrophysics Data System (ADS)

    Szwabiński, Janusz; Peķalski, Andrzej

    2006-01-01

    The influence of habitat destruction on a population of predators and prey is studied. We show, via Monte Carlo simulations of a lattice model, that with growing devastation the oscillations in the densities of both species, as well as cross-correlations between the two densities diminish. As should be expected, predators are more vulnerable and disappear before the prey. Devastation of the habitat is never beneficial and the percentage of coexisting (prey and predators) states decreases with destruction. Because of the high fragmentation of the environment in the case of large devastation, animals’ populations are separated into small sub-populations living in restricted areas. Such small populations become extinct more easily. We have also shown that in the case of large habitat devastation the density of the population of prey depends on its history.

  19. Assessment of lead uptake in reptilian prey species.

    PubMed

    Inouye, Laura S; Yoo, Leslie J; Talent, Larry G; Clarke, Joan U; Jones, Robert P; Steevens, Jeffery A; Boyd, Robert E

    2007-07-01

    As part of an investigation determining the trophically available fraction of metals in a model terrestrial food web, i.e., invertebrate prey to Western fence lizards (Sceloporus occidentalis), we evaluated the ability of several invertebrate prey to bioaccumulate lead and to form metals-rich granules, which are hypothesized to be non-available to predators. Crickets (Acheta domestica), tenebroid beetle larvae (Tenebrio molitor), and isopods (Porcellio scaber) were selected as model prey organisms. Lack of standard exposure methodologies for these species has presented a barrier to trophic transfer evaluations, as each species has particular requirements that create challenges for designing exposure conditions. We were able to devise exposure conditions for all three species that allow long-term exposure studies. All prey organisms accumulated lead from contaminated food, and for all species the majority of the accumulated Pb was associated with the exoskeleton (>50%), with metals-rich granules accounting for most of the remaining accumulated lead. PMID:17490716

  20. Pharmacokinetics of gentamicin in birds of prey.

    PubMed

    Bird, J E; Miller, K W; Larson, A A; Duke, G E

    1983-07-01

    The pharmacokinetics of gentamicin, including half-life, apparent volume of distribution, total body clearance, and fraction of drug absorbed from IM injection sites, were determined in 3 species of birds of prey (red-tailed hawks, great horned owls, and golden eagles). Significant differences (P less than 0.05) between species were found for the half-life and total body clearance values for this broad-spectrum antibiotic. The values for apparent volume of distribution and fraction absorbed did not differ among species and were similar to those reported in mammals. Rapid and relatively complete absorption from IM injection sites resulted in high bioavailability. After IV administration of 10 mg of gentamicin/kg of body weight, serum concentrations greater than 12 micrograms/ml were present for at least 2 hours and greater than 2 micrograms/ml for 4 to 6 hours. On the basis of the various determinations, an IM dose of 2.5 mg of gentamicin/kg given every 8 hours should provide therapeutic serum concentrations of gentamicin in the 3 species. PMID:6881663

  1. Enhancements to the Behavioral Parent Training Paradigm for Families of Children with ADHD: Review and Future Directions

    ERIC Educational Resources Information Center

    Chronis, Andrea M.; Chacko, Anil; Fabiano, Gregory A.; Wymbs, Brian T.; Pelham, William E., Jr.

    2004-01-01

    Behavioral parent training (BPT) is one of the empirically supported psychosocial treatments for ADHD. Over many years and in many studies, BPT has been documented to improve both child ADHD behavior and maladaptive parenting behavior. In some studies, BPT has also been found to result in benefits in additional domains, such as parenting stress…

  2. Curvature facilitates prey fixation in predatory insect claws.

    PubMed

    Petie, Ronald; Muller, Mees

    2007-02-21

    Insects show a large variety in prey capture strategies, with a correspondingly large diversity in predatory adaptations. We studied a specific type of predatory claws, these can for example be found in praying mantis species. The claw is closeable over its entire length and the prey is fixed between the femur (upper arm) and the tibia (lower arm) of the insect leg. The morphology of these predatory claws is diverse. Some species have straight claws covered with spines, while other species have smooth, curved claws. We have studied the mechanics of this femur-tibia type of predatory insect claws, by making a physical model, eventually trying to explain why in some insect species the claws are curved instead of straight. The main results are (1) when comparing curved claws to straight claws, curvature leads to a strong reduction of forces driving the prey away from the pivoting point, thereby reducing the need for friction generating structures. (2) In the curved claw model a position exists where the resulting force on the prey is exactly zero. This is because the normal forces on the femur and tibia are opposed, and in line. At this position the prey is perfectly clamped and not driven out of the claw. This feature does not exist in straight claws. (3) In the curved claw, the prey cannot be placed at a position further than a certain maximum distance from the pivoting point. Near this maximum position, the resulting force on the prey reaches high values because moment arms are near zero. (4) Between the zero position and the maximum position the resulting force is directed toward the pivoting point, which stabilizes prey fixation. PMID:17056069

  3. Developmental trajectory from early responses to transgressions to future antisocial behavior: Evidence for the role of the parent-child relationship from two longitudinal studies

    PubMed Central

    Kim, Sanghag; Kochanska, Grazyna; Boldt, Lea J.; Nordling, Jamie Koenig; O’Bleness, Jessica J.

    2014-01-01

    Parent-child relationships are critical in development, but much remains to be learned about mechanisms of their impact. We examined early parent-child relationship as a moderator of the developmental trajectory from children’s affective and behavioral responses to transgressions to future antisocial, externalizing behavior problems in Family Study (102 community mothers, fathers, and infants, followed through age 8) and Play Study (186 low-income, diverse mothers and toddlers, followed for 10 months). The relationship quality was indexed by attachment security in Family Study and maternal responsiveness in Play Study. Responses to transgressions (tense discomfort and reparation) were observed in laboratory mishaps that led children to believe they had damaged a valued object. Antisocial outcomes were rated by parents. In both studies, early relationship moderated the future developmental trajectory: Children’s attenuated tense discomfort predicted more antisocial outcomes, but only in insecure or unresponsive relationships. That risk was defused in secure or responsive relationships. Moderated mediation analyses in Family Study indicated that the links between low tense discomfort and future antisocial behavior in insecure parent-child dyads were mediated by parental stronger discipline pressure. By influencing indirectly future developmental sequelae, early relationship may increase or decrease the probability that the parent-child dyad will embark on a path toward antisocial outcomes. PMID:24280347

  4. Indirect evolutionary rescue: prey adapts, predator avoids extinction

    PubMed Central

    Yamamichi, Masato; Miner, Brooks E

    2015-01-01

    Recent studies have increasingly recognized evolutionary rescue (adaptive evolution that prevents extinction following environmental change) as an important process in evolutionary biology and conservation science. Researchers have concentrated on single species living in isolation, but populations in nature exist within communities of interacting species, so evolutionary rescue should also be investigated in a multispecies context. We argue that the persistence or extinction of a focal species can be determined solely by evolutionary change in an interacting species. We demonstrate that prey adaptive evolution can prevent predator extinction in two-species predator–prey models, and we derive the conditions under which this indirect evolutionary interaction is essential to prevent extinction following environmental change. A nonevolving predator can be rescued from extinction by adaptive evolution of its prey due to a trade-off for the prey between defense against predation and population growth rate. As prey typically have larger populations and shorter generations than their predators, prey evolution can be rapid and have profound effects on predator population dynamics. We suggest that this process, which we term ‘indirect evolutionary rescue’, has the potential to be critically important to the ecological and evolutionary responses of populations and communities to dramatic environmental change. PMID:26366196

  5. Snake modulates constriction in response to prey's heartbeat.

    PubMed

    Boback, Scott M; Hall, Allison E; McCann, Katelyn J; Hayes, Amanda W; Forrester, Jeffrey S; Zwemer, Charles F

    2012-06-23

    Many species of snakes use constriction-the act of applying pressure via loops of their trunk-to subdue and kill their prey. Constriction is costly and snakes must therefore constrict their prey just long enough to ensure death. However, it remains unknown how snakes determine when their prey is dead. Here, we demonstrate that boas (Boa constrictor) have the remarkable ability to detect a heartbeat in their prey and, based on this signal, modify the pressure and duration of constriction accordingly. We monitored pressure generated by snakes as they struck and constricted warm cadaveric rats instrumented with a simulated heart. Snakes responded to the beating heart by constricting longer and with greater total pressure than when constricting rats with no heartbeat. When the heart was stopped midway through the constriction, snakes abandoned constriction shortly after the heartbeat ceased. Furthermore, snakes naive to live prey also responded to the simulated heart, suggesting that this behaviour is at least partly innate. These results are an example of how snakes integrate physiological cues from their prey to modulate a complex and ancient behavioural pattern. PMID:22258447

  6. Sensory modulation and behavioral choice during feeding in the Australian frog, Cyclorana novaehollandiae.

    PubMed

    Valdez, C M; Nishikawa, K C

    1997-03-01

    This study investigates how visual and tactile sensory information, as well as biomechanical effects due to differences in physical characteristics of the prey, influence feeding behavior in the frog Cyclorana novaehollandiae. Video motion analysis was used to quantify movement patterns produced when feeding on five prey types (termites, waxworms, crickets, mice and earthworms). Twelve kinematic variables differed significantly among prey types, and twelve variables were correlated with prey characteristics (including mass, length, height and velocity of movement). Results indicate that C. novaehollandiae uses a different strategy to capture each prey type. Visual assessment of prey characteristics appeared to be more important in modulating feeding behavior that tactile cues or biomechanical effects. We propose a hierarchical hypothesis of behavioral choice, in which decisions are based primarily on visual analysis of prey characteristics. In this model, the frogs first choose between jaw prehension and tongue prehension based on prey size. If they have chosen jaw prehension, they next choose between upward or downward head rotation based on length and height of the prey. If they have chosen tongue prehension, they next choose between behavior for fast and slow prey. Final decisions may be the result of behavioral fine tuning based on tactile feedback. PMID:9048439

  7. Responses of movement-sensitive visual interneurons to prey-like stimuli in the praying mantis Sphodromantis lineola (Burmeister).

    PubMed

    Gonka, M D; Laurie, T J; Prete, F R

    1999-11-01

    Previous behavioral work using both mechanical and computer-generated visual stimuli has demonstrated that mantids use a computational algorithm to recognize prey similar to that used by some amphibian predators: A stimulus elicits prey capture behavior if it falls within a perceptual envelope defined by five fundamental stimulus parameters: (1) overall size, (2) length of the leading edge, (3) contrast to the background, (4) location in the visual field, and (5) apparent speed. In this study, we recorded simultaneously from both cervical nerve cords of monocular Sphodromantis lineola while they viewed the same visual stimuli successfully used in the behavioral studies. Extracellular recordings showed three consistently proportioned amplitude classes of movement-elicited spikes in each cord and these were repeatedly and reliably identifiable across mantids. Overall, the movement-elicited activity in both cords was dominated by very large spikes suggesting the existence of several large, descending movement-sensitive interneurons projecting both ipsilaterally and contralaterally from the optic lobes. However, only the largest contralateral spikes occurred preferentially to prey-like stimuli, mirrored the behavioral response curves generated by S. lineola to the same visual stimuli, and displayed activity peaks that were correlated with the times at which the mantid emitted predatory strikes. PMID:10640785

  8. Configural prey recognition by the praying mantis, Sphodromantis lineola (Burr.); effects of size and direction of movement.

    PubMed

    Prete, F R

    1990-01-01

    The visually released, predatory behaviors of approaching and striking at prey by the praying mantis, Sphodromantis lineola (Burr.), were measured in response to various moving, three-dimensional lure configurations. Lures varied in length (3, 7, 15, 25, 35, 50, 70 or 100 mm), thickness (i.e. width and height: 3, 7, 10, 15, 20 or 30 mm) and direction (approaching or moving orthogonally). Each of these three parameters has a significant effect on whether adult female S. lineola recognize a moving object as potential prey. Approaching lures are strong releasers of predatory behaviors when they are 3-35 mm long and 10 mm thick. Orthogonally moving lures, although overall poor releasers of predatory behavior, are at their strongest when 3-35 mm long but only 3 mm thick. These response patterns are similar to those for some anurans and urodeles, which also hunt small invertebrates with analogous behavioral repertoires. This suggests that these groups may have evolved similar algorithms for identifying prey in spite of dissimilar neural organization. PMID:2285856

  9. Dynamics and pattern formation in a diffusive predator-prey system with strong Allee effect in prey

    NASA Astrophysics Data System (ADS)

    Wang, Jinfeng; Shi, Junping; Wei, Junjie

    The dynamics of a reaction-diffusion predator-prey system with strong Allee effect in the prey population is considered. Nonexistence of nonconstant positive steady state solutions are shown to identify the ranges of parameters of spatial pattern formation. Bifurcations of spatially homogeneous and nonhomogeneous periodic solutions as well as nonconstant steady state solutions are studied. These results show that the impact of the Allee effect essentially increases the system spatiotemporal complexity.

  10. Comparing nearshore benthic and pelagic prey as mercury sources to lake fish: the importance of prey quality and mercury content.

    PubMed

    Karimi, Roxanne; Chen, Celia Y; Folt, Carol L

    2016-09-15

    Mercury (Hg) bioaccumulation in fish poses well-known health risks to wildlife and humans through fish consumption. Yet fish Hg concentrations are highly variable, and key factors driving this variability remain unclear. One little studied source of variation is the influence of habitat-specific feeding on Hg accumulation in lake fish. However, this is likely important because most lake fish feed in multiple habitats during their lives, and the Hg and caloric content of prey from different habitats can differ. This study used a three-pronged approach to investigate the extent to which habitat-specific prey determine differences in Hg bioaccumulation in fish. This study first compared Hg concentrations in common nearshore benthic invertebrates and pelagic zooplankton across five lakes and over the summer season in one lake, and found that pelagic zooplankton generally had higher Hg concentrations than most benthic taxa across lakes, and over a season in one lake. Second, using a bioenergetics model, the effects of prey caloric content from habitat-specific diets on fish growth and Hg accumulation were calculated. This model predicted that the consumption of benthic prey results in lower fish Hg concentrations due to higher prey caloric content and growth dilution (high weight gain relative to Hg from food), in addition to lower prey Hg levels. Third, using data from the literature, links between fish Hg content and the degree of benthivory, were examined, and showed that benthivory was associated with reduced Hg concentrations in lake fish. Taken together, these findings support the hypothesis that higher Hg content and lower caloric content make pelagic zooplankton prey greater sources of Hg for fish than nearshore benthic prey in lakes. Hence, habitat-specific foraging is likely to be a strong driver of variation in Hg levels within and between fish species. PMID:27173839

  11. Behaviorism

    ERIC Educational Resources Information Center

    Moore, J.

    2011-01-01

    Early forms of psychology assumed that mental life was the appropriate subject matter for psychology, and introspection was an appropriate method to engage that subject matter. In 1913, John B. Watson proposed an alternative: classical S-R behaviorism. According to Watson, behavior was a subject matter in its own right, to be studied by the…

  12. Interrupting peptidoglycan deacetylation during Bdellovibrio predator-prey interaction prevents ultimate destruction of prey wall, liberating bacterial-ghosts.

    PubMed

    Lambert, Carey; Lerner, Thomas R; Bui, Nhat Khai; Somers, Hannah; Aizawa, Shin-Ichi; Liddell, Susan; Clark, Ana; Vollmer, Waldemar; Lovering, Andrew L; Sockett, R Elizabeth

    2016-01-01

    The peptidoglycan wall, located in the periplasm between the inner and outer membranes of the cell envelope in Gram-negative bacteria, maintains cell shape and endows osmotic robustness. Predatory Bdellovibrio bacteria invade the periplasm of other bacterial prey cells, usually crossing the peptidoglycan layer, forming transient structures called bdelloplasts within which the predators replicate. Prey peptidoglycan remains intact for several hours, but is modified and then degraded by escaping predators. Here we show predation is altered by deleting two Bdellovibrio N-acetylglucosamine (GlcNAc) deacetylases, one of which we show to have a unique two domain structure with a novel regulatory"plug". Deleting the deacetylases limits peptidoglycan degradation and rounded prey cell "ghosts" persist after mutant-predator exit. Mutant predators can replicate unusually in the periplasmic region between the peptidoglycan wall and the outer membrane rather than between wall and inner-membrane, yet still obtain nutrients from the prey cytoplasm. Deleting two further genes encoding DacB/PBP4 family proteins, known to decrosslink and round prey peptidoglycan, results in a quadruple mutant Bdellovibrio which leaves prey-shaped ghosts upon predation. The resultant bacterial ghosts contain cytoplasmic membrane within bacteria-shaped peptidoglycan surrounded by outer membrane material which could have promise as "bacterial skeletons" for housing artificial chromosomes. PMID:27211869

  13. Interrupting peptidoglycan deacetylation during Bdellovibrio predator-prey interaction prevents ultimate destruction of prey wall, liberating bacterial-ghosts

    PubMed Central

    Lambert, Carey; Lerner, Thomas R.; Bui, Nhat Khai; Somers, Hannah; Aizawa, Shin-Ichi; Liddell, Susan; Clark, Ana; Vollmer, Waldemar; Lovering, Andrew L.; Sockett, R. Elizabeth

    2016-01-01

    The peptidoglycan wall, located in the periplasm between the inner and outer membranes of the cell envelope in Gram-negative bacteria, maintains cell shape and endows osmotic robustness. Predatory Bdellovibrio bacteria invade the periplasm of other bacterial prey cells, usually crossing the peptidoglycan layer, forming transient structures called bdelloplasts within which the predators replicate. Prey peptidoglycan remains intact for several hours, but is modified and then degraded by escaping predators. Here we show predation is altered by deleting two Bdellovibrio N-acetylglucosamine (GlcNAc) deacetylases, one of which we show to have a unique two domain structure with a novel regulatory”plug”. Deleting the deacetylases limits peptidoglycan degradation and rounded prey cell “ghosts” persist after mutant-predator exit. Mutant predators can replicate unusually in the periplasmic region between the peptidoglycan wall and the outer membrane rather than between wall and inner-membrane, yet still obtain nutrients from the prey cytoplasm. Deleting two further genes encoding DacB/PBP4 family proteins, known to decrosslink and round prey peptidoglycan, results in a quadruple mutant Bdellovibrio which leaves prey-shaped ghosts upon predation. The resultant bacterial ghosts contain cytoplasmic membrane within bacteria-shaped peptidoglycan surrounded by outer membrane material which could have promise as “bacterial skeletons” for housing artificial chromosomes. PMID:27211869

  14. Middle Childhood Support-Seeking Behavior during Stress: Links with Self-Reported Attachment and Future Depressive Symptoms

    ERIC Educational Resources Information Center

    Dujardin, Adinda; Santens, Tara; Braet, Caroline; De Raedt, Rudi; Vos, Pieter; Maes, Bea; Bosmans, Guy

    2016-01-01

    This study tested whether children's more anxious and avoidant attachment is linked to decreased support-seeking behavior toward their mother during stress in middle childhood, and whether children's decreased support-seeking behavior enhances the impact of experiencing life events on the increase of depressive symptoms 18 months later.…

  15. Reflections on the Future of Council for Children with Behavioral Disorders: A Response to Colvin, Forness, and Nelson

    ERIC Educational Resources Information Center

    Peck, Alec F.; Albrecht, Susan Fread; George, Cheryl L.; Mathur, Sarup R.; Paget, Mike; Ryan, Joseph B.; White, Richard B.; Baker, Diana

    2012-01-01

    In issue 37(1) of this journal, the authors published the findings of three studies addressing the status of Council for Children with Behavioral Disorders (CCBD) as an organization and of the field of special education for students with emotional and behavioral disorders (E/BD). In order to continue discussion of the status of CCBD, the editors…

  16. Behavioral Treatment of Drooling: A Methodological Critique of the Literature with Clinical Guidelines and Suggestions for Future Research

    ERIC Educational Resources Information Center

    Van der Burg, Jan J. W.; Didden, Robert; Jongerius, Peter H.; Rotteveel, Jan J.

    2007-01-01

    Many children with mental retardation and developmental disabilities suffer from the consequences of chronic drooling. Behavioral treatment for drooling should be considered before other, more intrusive treatments such as medication and surgery are implemented. However, empirical studies on behavioral procedures are scarce. This article reviews 19…

  17. Effects of School-Wide Positive Behavioral Interventions and Supports on Internalizing Problems: Current Evidence and Future Directions

    ERIC Educational Resources Information Center

    McIntosh, Kent; Ty, Sophie V.; Miller, Lynn D.

    2014-01-01

    School-Wide Positive Behavioral Interventions and Supports (SWPBIS) has a large evidence base for preventing and addressing externalizing problem behavior, but there is little research examining its effects on internalizing problems, such as anxiety and depression. Given the prevalence of internalizing problems in today's children and youth,…

  18. How Nature-Based Tourism Might Increase Prey Vulnerability to Predators.

    PubMed

    Geffroy, Benjamin; Samia, Diogo S M; Bessa, Eduardo; Blumstein, Daniel T

    2015-12-01

    Tourism can be deleterious for wildlife because it triggers behavioral changes in individuals with cascading effects on populations and communities. Among these behavioral changes, animals around humans often reduce their fearfulness and antipredator responses towards humans. A straightforward prediction is that habituation to humans associated with tourism would negatively influence reaction to predators. This could happen indirectly, where human presence decreases the number of natural predators and thus prey become less wary, or directly, where human-habituated individuals become bolder and thus more vulnerable to predation. Building on ideas from the study of traits associated with domestication and urbanization, we develop a framework to understand how behavioral changes associated with nature-based tourism can impact individual fitness, and thus the demographic trajectory of a population. PMID:26475119

  19. Changing health behaviors to improve health outcomes after angioplasty: a randomized trial of net present value versus future value risk communication

    PubMed Central

    Charlson, M. E.; Peterson, J. C.; Boutin-Foster, C.; Briggs, W. M.; Ogedegbe, G. G.; McCulloch, C. E.; Hollenberg, J.; Wong, C.; Allegrante, J. P.

    2008-01-01

    Patients who have undergone angioplasty experience difficulty modifying at-risk behaviors for subsequent cardiac events. The purpose of this study was to test whether an innovative approach to framing of risk, based on ‘net present value’ economic theory, would be more effective in behavioral intervention than the standard ‘future value approach’ in reducing cardiovascular morbidity and mortality following angioplasty. At baseline, all patients completed a health assessment, recieved an individualized risk profile and selected risk factors for modification. The intervention randomized patients into two varying methods for illustrating positive effects of behavior change. For the experimental group, each selected risk factor was assigned a numeric biologic age (the net present value) that approximated the relative potential to improve current health status and quality of life when modifying that risk factor. In the control group, risk reduction was framed as the value of preventing future health problems. Ninety-four percent of patients completed 2-year follow-up. There was no difference between the rates of death, stroke, myocardial infarction, Class II–IV angina or severe ischemia (on non-invasive testing) between the net present value group and the future value group. Our results show that a net present risk communication intervention did not result in significant differences in health outcomes. PMID:18025064

  20. Linking animal-borne video to accelerometers reveals prey capture variability

    PubMed Central

    Watanabe, Yuuki Y.; Takahashi, Akinori

    2013-01-01

    Understanding foraging is important in ecology, as it determines the energy gains and, ultimately, the fitness of animals. However, monitoring prey captures of individual animals is difficult. Direct observations using animal-borne videos have short recording periods, and indirect signals (e.g., stomach temperature) are never validated in the field. We took an integrated approach to monitor prey captures by a predator by deploying a video camera (lasting for 85 min) and two accelerometers (on the head and back, lasting for 50 h) on free-swimming Adélie penguins. The movies showed that penguins moved the heads rapidly to capture krill in midwater and fish (Pagothenia borchgrevinki) underneath the sea ice. Captures were remarkably fast (two krill per second in swarms) and efficient (244 krill or 33 P. borchgrevinki in 78–89 min). Prey captures were detected by the signal of head acceleration relative to body acceleration with high sensitivity and specificity (0.83–0.90), as shown by receiver-operating characteristic analysis. Extension of signal analysis to the entire behavioral records showed that krill captures were spatially and temporally more variable than P. borchgrevinki captures. Notably, the frequency distribution of krill capture rate closely followed a power-law model, indicating that the foraging success of penguins depends on a small number of very successful dives. The three steps illustrated here (i.e., video observations, linking video to behavioral signals, and extension of signal analysis) are unique approaches to understanding the spatial and temporal variability of ecologically important events such as foraging. PMID:23341596

  1. Predator-Prey model for haloes in Saturn's A ring

    NASA Astrophysics Data System (ADS)

    Esposito, Larry W.; Bradley, E. Todd; Colwell, Joshua E.; Madhusudhanan, Prasanna; Sremcevic, Miodrag

    2013-04-01

    UVIS SOI reflectance spectra show bright 'haloes' around the locations of some of the strongest resonances in Saturn's A ring (Esposito etal 2005). UV spectra constrain the size and composition of the icy ring particles (Bradley etal 2010, 2012). The correspondence of IR, UV spectroscopy, HSP wavelet analysis indicate that we detect the same phenomenon. We investigate the Janus 2:1. 4:3, 5:3, 6:5 and Mimas 5:3 inner Lindblad resonances as well as at the Mimas 5:3 vertical resonance (bending wave location). Models of ring particle regolith evolution (Elliott and Esposito 2010) indicate the deeper regolith is made of older and purer ice. The strong resonances can cause streamline crowding (Lewis and Stewart 2005) which damps the interparticle velocity, allowing temporary clumps to grow, which in turn increase the velocity, eroding the clumps and releasing smaller particles and regolith (see the predator-prey model of Esposito etal 2012). This cyclic behavior, driven by the resonant perturbation from the moon, can yield collision velocities at particular azimuths greater than 1m/sec, sufficient to erode the aggregates (Blum 2006), exposing older, purer materials: In the perturbed region, collisions erode the regolith, removing smaller particles. The released regolith material settles in the less perturbed neighboring regions. Diffusion spreads these ring particles with smaller regolith into a 'halo'. Thus, the radial location of the strongest resonances can be where we find both large aggregates and disrupted fragments, in a balance maintained by the periodic moon forcing. If this stirring exposes older, and purer ice, the velocity threshold for eroding the aggregates can explain why only the strongest Lindblad resonances show haloes. Diffusion can explain the morphology of these haloes, although they are not well-resolved spatially by UVIS.

  2. Mothers' power assertion; children's negative, adversarial orientation; and future behavior problems in low-income families: early maternal responsiveness as a moderator of the developmental cascade.

    PubMed

    Kim, Sanghag; Kochanska, Grazyna

    2015-02-01

    Parental power assertion, a key dimension of family environment, generally sets in motion detrimental developmental cascades; however, evidence suggests that other qualities of parenting, such as responsiveness, can significantly moderate those processes. Mechanisms that account for such moderating effects are not fully understood. We propose a conceptual model of processes linking parental power assertion, parental responsiveness, children's negative, adversarial, rejecting orientation toward the parent, and behavior problems. We test that model in a short-term longitudinal design involving 186 low-income, ethnically diverse mothers and their toddlers. When children were 30 months, the dyads were observed in multiple, lengthy, naturalistic laboratory interactions to assess behaviorally mothers' responsiveness and their power-assertive control style. At 33 months, we observed behavioral indicators of children's negative, adversarial, rejecting orientation toward the mothers in several naturalistic and standardized paradigms. At 40 months, mothers rated children's behavior problems. The proposed moderated mediation sequence, tested using a new approach, PROCESS (Hayes, 2013), was supported. The indirect effect from maternal power assertion to children's negative, adversarial orientation to future behavior problems was present when mothers' responsiveness was either low or average but absent when mothers were highly responsive. This study elucidates a potential process that may link parental power assertion with behavior problems and highlights how positive aspects of parenting can moderate this process and defuse maladaptive developmental cascades. It also suggests possible targets for parenting intervention and prevention efforts. PMID:25401483

  3. Mothers’ Power Assertion, Children’s Negative, Adversarial Orientation, and Future Behavior Problems in Low-Income Families: Early Maternal Responsiveness as a Moderator of the Developmental Cascade

    PubMed Central

    Kim, Sanghag; Kochanska, Grazyna

    2014-01-01

    Parental power assertion, a key dimension of family environment, generally sets in motion detrimental developmental cascades; however, evidence suggests that other qualities of parenting, such as responsiveness, can significantly moderate those processes. Mechanisms that account for such moderating effects are not fully understood. We propose a conceptual model of processes linking parental power assertion, parental responsiveness, children’s negative, adversarial, rejecting orientation toward the parent, and behavior problems. We test that model in a short-term longitudinal design involving 186 low-income, ethnically diverse mothers and their toddlers. When children were 30 months, the dyads were observed in multiple, lengthy, naturalistic laboratory interactions to assess behaviorally mothers’ responsiveness and their power-assertive control style. At 33 months, we observed behavioral indicators of children’s negative, adversarial, rejecting orientation toward the mothers in several naturalistic and standardized paradigms. At 40 months, mothers rated children’s behavior problems. The proposed moderated mediation sequence, tested using a new approach, PROCESS (Hayes, 2013), was supported. The indirect effect from maternal power assertion to children’s negative, adversarial orientation to future behavior problems was present when mothers’ responsiveness was either low or average but absent when mothers were highly responsive. This study elucidates a potential process that may link parental power assertion with behavior problems and highlights how positive aspects of parenting can moderate this process and defuse maladaptive developmental cascades. It also suggests possible targets for parenting intervention and prevention efforts. PMID:25401483

  4. REM Sleep Behavior Disorder: Updated Review of the Core Features, the RBD-Neurodegenerative Disease Association, Evolving Concepts, Controversies, and Future Directions

    PubMed Central

    Boeve, Bradley F.

    2010-01-01

    Rapid eye movement (REM) sleep behavior disorder (RBD) is a parasomnia manifested by vivid, often frightening dreams associated with simple or complex motor behavior during REM sleep. Patients appear to “act out their dreams,” in which the exhibited behaviors mirror the content of the dreams, and the dream content often involves a chasing or attacking theme. The polysomnographic features of RBD include increased electromyographic tone +/- dream enactment behavior during REM sleep. Management with counseling and pharmacologic measures is usually straight-forward and effective. In this review, the terminology, clinical and polysomnographic features, demographic and epidemiologic features, diagnostic criteria, differential diagnosis, and management strategies are discussed. Recent data on the suspected pathophysiologic mechanisms of RBD are also reviewed. The literature and our institutional experience on RBD are next discussed, with an emphasis on the RBD-neurodegenerative disease association and particularly the RBD-synucleinopathy association. Several issues relating to evolving concepts, controversies, and future directions are then reviewed, with an emphasis on idiopathic RBD representing an early feature of a neurodegenerative disease and particularly an evolving synucleinopathy. Planning for future therapies that impact patients with idiopathic RBD is reviewed in detail. PMID:20146689

  5. Evidence of weaker phenotypic plasticity by prey to novel cues from non-native predators.

    PubMed

    Hollander, Johan; Bourdeau, Paul E

    2016-08-01

    A central question in evolutionary biology is how coevolutionary history between predator and prey influences their interactions. Contemporary global change and range expansion of exotic organisms impose a great challenge for prey species, which are increasingly exposed to invading non-native predators, with which they share no evolutionary history. Here, we complete a comprehensive survey of empirical studies of coevolved and naive predator-prey interactions to assess whether a shared evolutionary history with predators influences the magnitude of predator-induced defenses mounted by prey. Using marine bivalves and gastropods as model prey, we found that coevolved prey and predator-naive prey showed large discrepancies in magnitude of predator-induced phenotypic plasticity. Although naive prey, predominantly among bivalve species, did exhibit some level of plasticity - prey exposed to native predators showed significantly larger amounts of phenotypic plasticity. We discuss these results and the implications they may have for native communities and ecosystems. PMID:27551388

  6. Comparative Growth and Development of Spiders Reared on Live and Dead Prey

    PubMed Central

    Peng, Yu; Zhang, Fan; Gui, Shaolan; Qiao, Huping; Hose, Grant C.

    2013-01-01

    Scavenging (feeding on dead prey) has been demonstrated across a number of spider families, yet the implications of feeding on dead prey for the growth and development of individuals and population is unknown. In this study we compare the growth, development, and predatory activity of two species of spiders that were fed on live and dead prey. Pardosa astrigera (Lycosidae) and Hylyphantes graminicola (Lyniphiidae) were fed live or dead fruit flies, Drosophila melanogaster. The survival of P. astrigera and H. graminicola was not affected by prey type. The duration of late instars of P. astrigera fed dead prey were longer and mature spiders had less protein content than those fed live prey, whereas there were no differences in the rate of H. graminicola development, but the mass of mature spiders fed dead prey was greater than those fed live prey. Predation rates by P. astrigera did not differ between the two prey types, but H. graminicola had a higher rate of predation on dead than alive prey, presumably because the dead flies were easier to catch and handle. Overall, the growth, development and reproduction of H. graminicola reared with dead flies was better than those reared on live flies, yet for the larger P. astrigera, dead prey may suit smaller instars but mature spiders may be best maintained with live prey. We have clearly demonstrated that dead prey may be suitable for rearing spiders, although the success of the spiders fed such prey appears size- and species specific. PMID:24386248

  7. Prey size selection and cannibalistic behaviour of juvenile barramundi Lates calcarifer.

    PubMed

    Ribeiro, F F; Qin, J G

    2015-05-01

    This study assessed the cannibalistic behaviour of juvenile barramundi Lates calcarifer and examined the relationship between prey size selection and energy gain of cannibals. Prey handling time and capture success by cannibals were used to estimate the ratio of energy gain to energy cost in prey selection. Cannibals selected smaller prey despite its capability of ingesting larger prey individuals. In behavioural analysis, prey handling time significantly increased with prey size, but it was not significantly affected by cannibal size. Conversely, capture success significantly decreased with the increase of both prey and cannibal sizes. The profitability indices showed that the smaller prey provides the most energy return for cannibals of all size classes. These results indicate that L. calcarifer cannibals select smaller prey for more profitable return. The behavioural analysis, however, indicates that L. calcarifer cannibals attack prey of all size at a similar rate but ingest smaller prey more often, suggesting that prey size selection is passively orientated rather than at the predator's choice. The increase of prey escape ability and morphological constraint contribute to the reduction of intracohort cannibalism as fish grow larger. This study contributes to the understanding of intracohort cannibalism and development of strategies to reduce fish cannibalistic mortalities. PMID:25801794

  8. Prey scan at random to evade observant predators.

    PubMed Central

    Scannell, J.; Roberts, G.; Lazarus, J.

    2001-01-01

    Anti-predator scans by animals occur with very irregular timing, so that the initiation of scans resembles a random, Poisson-like, process. At first sight, this seems both dangerous (predators could exploit the long intervals) and wastefull (scans after very short intervals are relatively uninformative). We explored vigilance timing using a new model that allows both predators and prey to vary their behaviour. Given predators that attack at random with respect to prey behaviour, constant inter-scan intervals minimize predation risk. However, if prey scan regularly to minimize their risk from randomly attacking predators, they become more vulnerable to predators that initiate attacks when the inter-scan intervals begin. If, in order to defeat this tactic, prey choose extremely variable inter-scan intervals, they become more vulnerable to predators who wait for long intervals before launching attacks. Only if predators can monitor the variability of inter-scan intervals and either attack immediately (if variability is too low) or wait for long intervals to attack (if variability is too high) does the empirically observed pattern of Poisson-like scanning become the optimal prey strategy. PMID:11296867

  9. Bacterial predator-prey dynamics in microscale patchy landscapes.

    PubMed

    Hol, Felix J H; Rotem, Or; Jurkevitch, Edouard; Dekker, Cees; Koster, Daniel A

    2016-02-10

    Soil is a microenvironment with a fragmented (patchy) spatial structure in which many bacterial species interact. Here, we explore the interaction between the predatory bacterium Bdellovibrio bacteriovorus and its prey Escherichia coli in microfabricated landscapes. We ask how fragmentation influences the prey dynamics at the microscale and compare two landscape geometries: a patchy landscape and a continuous landscape. By following the dynamics of prey populations with high spatial and temporal resolution for many generations, we found that the variation in predation rates was twice as large in the patchy landscape and the dynamics was correlated over shorter length scales. We also found that while the prey population in the continuous landscape was almost entirely driven to extinction, a significant part of the prey population in the fragmented landscape persisted over time. We observed significant surface-associated growth, especially in the fragmented landscape and we surmise that this sub-population is more resistant to predation. Our results thus show that microscale fragmentation can significantly influence bacterial interactions. PMID:26865299

  10. Dynamics of a predator-prey model with Allee effect and prey group defense

    NASA Astrophysics Data System (ADS)

    Saleh, Khairul

    2015-02-01

    Dynamical properties of a Gauss type of planar predator-prey system with Allee effect and non-monotonic response function are discussed. We are interested in persistent features lying in the first quadrant, which amount to structurally stable phase portraits. We show that all positive solutions are uniformly bounded. It is also proved that the system has at most two equilibria in the interior of the first quadrant and can exhibit interesting bifurcation phenomena, including Bogdanov-Takens, Hopf, transcritical and saddle-node bifurcations. The system may have a stable periodic orbit, or a homoclinic loop, or a heteroclinic connection, a saddle point, or a stable focus, depending on parameter values. Biologically, both populations may survive for certain values of parameters. Computer simulations are also given in support of the conclusions.

  11. Spatial Distribution and Temporal Patterns of Cassin's Auklet Foraging and Their Euphausiid Prey in a Variable Ocean Environment.

    PubMed

    Manugian, Suzanne; Elliott, Meredith L; Bradley, Russ; Howar, Julie; Karnovsky, Nina; Saenz, Benjamin; Studwell, Anna; Warzybok, Pete; Nur, Nadav; Jahncke, Jaime

    2015-01-01

    Krill (Euphausiids) play a vital ecosystem role in many of the world's most productive marine regions, providing an important trophic linkage. We introduce a robust modeling approach to link Cassin's auklet (Ptychoramphus aleuticus) abundance and distribution to large-scale and local oceanic and atmospheric conditions and relate these patterns to similarly modeled distributions of an important prey resource, krill. We carried out at-sea strip transect bird surveys and hydroacoustic assessments of euphausiids (2004-2013). Data informed separate, spatially-explicit predictive models of Cassin's auklet abundance (zero-inflated negative binomial regression) and krill biomass (two-part model) based on these surveys. We established the type of prey responsible for acoustic backscatter by conducting net tows of the upper 50 m during surveys. We determined the types of prey fed to Cassin's auklet chicks by collecting diet samples from provisioning adults. Using time-depth-recorders, we found Cassin's auklets utilized consistent areas in the upper water column, less than 30 m, where krill could be found (99.5% of dives were less than 30 m). Birds primarily preyed upon two species of euphausiids, Euphausia pacifica and Thysanoessa spinifera, which were available in the upper water column. Cassin's auklet abundance was best predicted by both large scale and localized oceanic processes (upwelling) while krill biomass was best predicted by local factors (temperature, salinity, and fluorescence) and both large scale and localized oceanic processes (upwelling). Models predicted varying krill and bird distribution by month and year. Our work informs the use of Cassin's auklet as a valuable indicator or krill abundance and distribution and strengthens our understanding of the link between Cassin's auklet and its primary prey. We expect future increases in frequency and magnitude of anomalous ocean conditions will result in decreased availability of krill leading to declines in the

  12. Spatial Distribution and Temporal Patterns of Cassin’s Auklet Foraging and Their Euphausiid Prey in a Variable Ocean Environment

    PubMed Central

    Manugian, Suzanne; Elliott, Meredith L.; Bradley, Russ; Howar, Julie; Karnovsky, Nina; Saenz, Benjamin; Studwell, Anna; Warzybok, Pete; Nur, Nadav; Jahncke, Jaime

    2015-01-01

    Krill (Euphausiids) play a vital ecosystem role in many of the world’s most productive marine regions, providing an important trophic linkage. We introduce a robust modeling approach to link Cassin’s auklet (Ptychoramphus aleuticus) abundance and distribution to large-scale and local oceanic and atmospheric conditions and relate these patterns to similarly modeled distributions of an important prey resource, krill. We carried out at-sea strip transect bird surveys and hydroacoustic assessments of euphausiids (2004–2013). Data informed separate, spatially-explicit predictive models of Cassin’s auklet abundance (zero-inflated negative binomial regression) and krill biomass (two-part model) based on these surveys. We established the type of prey responsible for acoustic backscatter by conducting net tows of the upper 50 m during surveys. We determined the types of prey fed to Cassin’s auklet chicks by collecting diet samples from provisioning adults. Using time-depth-recorders, we found Cassin’s auklets utilized consistent areas in the upper water column, less than 30 m, where krill could be found (99.5% of dives were less than 30 m). Birds primarily preyed upon two species of euphausiids, Euphausia pacifica and Thysanoessa spinifera, which were available in the upper water column. Cassin’s auklet abundance was best predicted by both large scale and localized oceanic processes (upwelling) while krill biomass was best predicted by local factors (temperature, salinity, and fluorescence) and both large scale and localized oceanic processes (upwelling). Models predicted varying krill and bird distribution by month and year. Our work informs the use of Cassin’s auklet as a valuable indicator or krill abundance and distribution and strengthens our understanding of the link between Cassin’s auklet and its primary prey. We expect future increases in frequency and magnitude of anomalous ocean conditions will result in decreased availability of krill leading

  13. The Relative Influence of Competition and Prey Defenses on the Phenotypic Structure of Insectivorous Bat Ensembles in Southern Africa

    PubMed Central

    Schoeman, M. Corrie; Jacobs, David S.

    2008-01-01

    Deterministic filters such as competition and prey defences should have a strong influence on the community structure of animals such as insectivorous bats that have life histories characterized by low fecundity, low predation risk, long life expectancy, and stable populations. We investigated the relative influence of these two deterministic filters on the phenotypic structure of insectivorous bat ensembles in southern Africa. We used null models to simulate the random phenotypic patterns expected in the absence of competition or prey defences and analysed the deviations of the observed phenotypic pattern from these expected random patterns. The phenotypic structure at local scales exhibited non-random patterns consistent with both competition and prey defense hypotheses. There was evidence that competition influenced body size distribution across ensembles. Competition also influenced wing and echolocation patterns in ensembles and in functional foraging groups with high species richness or abundance. At the same time, prey defense filters influenced echolocation patterns in two species-poor ensembles. Non-random patterns remained evident even after we removed the influence of body size from wing morphology and echolocation parameters taking phylogeny into account. However, abiotic filters such as geographic distribution ranges of small and large-bodied species, extinction risk, and the physics of flight and sound probably also interacted with biotic filters at local and/or regional scales to influence the community structure of sympatric bats in southern Africa. Future studies should investigate alternative parameters that define bat community structure such as diet and abundance to better determine the influence of competition and prey defences on the structure of insectivorous bat ensembles in southern Africa. PMID:19005563

  14. Once is too much: Conditioned aversion develops immediately and predicts future cocaine self-administration behavior in rats

    PubMed Central

    Colechio, Elizabeth M.; Imperio, Caesar G.; Grigson, Patricia S.

    2014-01-01

    Rats emit aversive taste reactivity (TR) behavior (i.e., gapes) following intraoral delivery of a cocaine-paired taste cue and greater conditioned aversive TR at the end of training predicts greater drug-seeking and taking. Here, we examined the development of this conditioned aversive TR behavior on a trial by trial basis in an effort to determine when the change in behavior occurs and whether early changes in this behavior can be used to predict later drug-taking. The results show that conditioned aversive TR to a cocaine-paired cue occurs very early in training (i.e., following as few as 1 – 2 taste-drug pairings) and, importantly, that it can be used to predict later drug-seeking and drug-taking in rats. PMID:24773440

  15. Planning for a brighter future: a review of sun protection and barriers to behavioral change in children and adolescents.

    PubMed

    Dadlani, Chicky; Orlow, Seth J

    2008-01-01

    Skin cancer is one of the most preventable groups of malignancies; however, skin cancer incidence continues to rise in the United States. The relationship between skin cancer and ultraviolet (UV) radiation is well known. Many interventions to prevent skin cancer by reducing exposure to UV radiation have been employed throughout the United States. Studies show an increase in knowledge and awareness regarding sun exposure and skin cancer. Unfortunately, sun protection interventions are slow at effecting behavioral change. In this review, we examine current barriers facing youth today in regards to sun protection practices, appropriate age groups to target for intervention, proposed methods of sun protection, the influence of role models in changing sun protective behavior, the stages of behavioral change, and characteristics and techniques of sun protection programs that can not only increase knowledge but actually elicit changes in sun protection behavior. PMID:19061583

  16. Feeding by the newly described mixotrophic dinoflagellate Paragymnodinium shiwhaense: feeding mechanism, prey species, and effect of prey concentration.

    PubMed

    Yoo, Yeong Du; Jeong, Hae Jin; Kang, Nam Seon; Song, Jae Yoon; Kim, Kwang Young; Lee, Gitack; Kim, Juhyoung

    2010-01-01

    To investigate the feeding by the newly described mixotrophic dinoflagellate Paragymnodinium shiwhaense (GenBank accession number=AM408889), we explored the feeding process and the kinds of prey species that P. shiwhaense is able to feed on using several different types of microscopes, including a transmission electron microscope and high-resolution video-microscopy. In addition, we measured the growth and ingestion rates of P. shiwhaense on its optimal algal prey Amphidinium carterae as a function of prey concentration. We also measured these parameters for edible prey at a single concentration at which the growth and ingestion rates of P. shiwhaense on A. carterae were saturated. Paragymnodinium shiwhaense feed on algal prey using a peduncle after anchoring the prey by a tow filament. Among the algal prey offered, P. shiwhaense ingested small algal species that had equivalent spherical diameters (ESDs) < or =11 microm (e.g. the prymnesiophyte Isochrysis galbana, the cryptophytes Teleaulax sp. and Rhodomonas salina, the raphidophyte Heterosigma akashiwo, and the dinoflagellates Heterocapsa rotundata and A. carterae). However, it did not feed on larger algal species that had ESDs > or =12 microm (e.g. the dinoflagellates Prorocentrum minimum, Heterocapsa triquetra, Scrippsiella trochoidea, Alexandrium tamarense, Prorocentrum micans, Gymnodinium catenatum, Akashiwo sanguinea, and Lingulodinium polyedrum) or the small diatom Skeletonema costatum. The specific growth rates for P. shiwhaense feeding upon A. carterae increased rapidly with increasing mean prey concentration before saturating at concentrations of ca. 350 ng C/ml (5,000 cells/ml). The maximum specific growth rate (i.e. mixotrophic growth) of P. shiwhaense on A. carterae was 1.097/d at 20 degrees C under a 14:10 h light-dark cycle of 20 microE/m(2)/s, while its growth rate (i.e. phototrophic growth) under the same light conditions without added prey was -0.224/d. The maximum ingestion and clearance rates

  17. Aggregation increases prey survival time in group chase and escape

    NASA Astrophysics Data System (ADS)

    Yang, Sicong; Jiang, Shijie; Jiang, Li; Li, Geng; Han, Zhangang

    2014-08-01

    Recently developed chase-and-escape models have addressed a fascinating pursuit-and-evasion problem that may have both theoretical significance and potential applications. We introduce three aggregation strategies for the prey in a group chase model on a lattice. Simulation results show that aggregation dramatically increases the group survival time, even allowing immortal prey. The average survival time τ and the aggregation probability P have a power-law dependence of \\tau \\sim {{(1-P)}^{-1}} for P\\in [0.9,0.997]. With increasing numbers of predators, there is still a phase transition. When the number of predators is less than the critical point value, the prey group survival time increases significantly.

  18. How sailfish use their bills to capture schooling prey.

    PubMed

    Domenici, P; Wilson, A D M; Kurvers, R H J M; Marras, S; Herbert-Read, J E; Steffensen, J F; Krause, S; Viblanc, P E; Couillaud, P; Krause, J

    2014-06-01

    The istiophorid family of billfishes is characterized by an extended rostrum or 'bill'. While various functions (e.g. foraging and hydrodynamic benefits) have been proposed for this structure, until now no study has directly investigated the mechanisms by which billfishes use their rostrum to feed on prey. Here, we present the first unequivocal evidence of how the bill is used by Atlantic sailfish (Istiophorus albicans) to attack schooling sardines in the open ocean. Using high-speed video-analysis, we show that (i) sailfish manage to insert their bill into sardine schools without eliciting an evasive response and (ii) subsequently use their bill to either tap on individual prey targets or to slash through the school with powerful lateral motions characterized by one of the highest accelerations ever recorded in an aquatic vertebrate. Our results demonstrate that the combination of stealth and rapid motion make the sailfish bill an extremely effective feeding adaptation for capturing schooling prey. PMID:24759865

  19. How sailfish use their bills to capture schooling prey

    PubMed Central

    Domenici, P.; Wilson, A. D. M.; Kurvers, R. H. J. M.; Marras, S.; Herbert-Read, J. E.; Steffensen, J. F.; Krause, S.; Viblanc, P. E.; Couillaud, P.; Krause, J.

    2014-01-01

    The istiophorid family of billfishes is characterized by an extended rostrum or ‘bill’. While various functions (e.g. foraging and hydrodynamic benefits) have been proposed for this structure, until now no study has directly investigated the mechanisms by which billfishes use their rostrum to feed on prey. Here, we present the first unequivocal evidence of how the bill is used by Atlantic sailfish (Istiophorus albicans) to attack schooling sardines in the open ocean. Using high-speed video-analysis, we show that (i) sailfish manage to insert their bill into sardine schools without eliciting an evasive response and (ii) subsequently use their bill to either tap on individual prey targets or to slash through the school with powerful lateral motions characterized by one of the highest accelerations ever recorded in an aquatic vertebrate. Our results demonstrate that the combination of stealth and rapid motion make the sailfish bill an extremely effective feeding adaptation for capturing schooling prey. PMID:24759865

  20. Biomechanics (Communication arising): prey attack by a large theropod dinosaur.

    PubMed

    Frazzetta, T H; Kardong, Kenneth V

    2002-03-28

    Prey-capture strategies in carnivorous dinosaurs have been inferred from the biomechanical features of their tooth structure, the estimated bite force produced, and their diet. Rayfield et al. have used finite-element analysis (FEA) to investigate such structure-function relationships in Allosaurus fragilis, and have found that the skull was designed to bear more stress than could be generated by simple biting. They conclude that this large theropod dinosaur delivered a chop-and-slash 'hatchet' blow to its prey, which it approached with its mouth wide open before driving its upper tooth row downwards. We argue that this mode of predation is unlikely, and that the FEA results, which relate to an 'overengineered' skull, are better explained by the biomechanical demands of prey capture. Understanding the mechanics of predation is important to our knowledge of the feeding habits of carnivorous dinosaurs and for accurate reconstruction their lifestyles. PMID:11919619

  1. Persistence in nonautonomous predator-prey systems with infinite delays

    NASA Astrophysics Data System (ADS)

    Teng, Zhidong; Rehim, Mehbuba

    2006-12-01

    This paper studies the general nonautonomous predator-prey Lotka-Volterra systems with infinite delays. The sufficient and necessary conditions of integrable form on the permanence and persistence of species are established. A very interesting and important property of two-species predator-prey systems is discovered, that is, the permanence of species and the existence of a persistent solution are each other equivalent. Particularly, for the periodic system with delays, applying these results, the sufficient and necessary conditions on the permanence and the existence of positive periodic solutions are obtained. Some well-known results on the nondelayed periodic predator-prey Lotka-Volterra systems are strongly improved and extended to the delayed case.

  2. Acoustic shadows help gleaning bats find prey, but may be defeated by prey acoustic camouflage on rough surfaces

    PubMed Central

    Clare, Elizabeth L; Holderied, Marc W

    2015-01-01

    Perceptual abilities of animals, like echolocating bats, are difficult to study because they challenge our understanding of non-visual senses. We used novel acoustic tomography to convert echoes into visual representations and compare these cues to traditional echo measurements. We provide a new hypothesis for the echo-acoustic basis of prey detection on surfaces. We propose that bats perceive a change in depth profile and an ‘acoustic shadow’ cast by prey. The shadow is more salient than prey echoes and particularly strong on smooth surfaces. This may explain why bats look for prey on flat surfaces like leaves using scanning behaviour. We propose that rather than forming search images for prey, whose characteristics are unpredictable, predators may look for disruptions to the resting surface (acoustic shadows). The fact that the acoustic shadow is much fainter on rougher resting surfaces provides the first empirical evidence for ‘acoustic camouflage’ as an anti-predator defence mechanism. DOI: http://dx.doi.org/10.7554/eLife.07404.001 PMID:26327624

  3. Predatory Strategies and Behavioral Diversity.

    ERIC Educational Resources Information Center

    Bekoff, Marc

    1983-01-01

    Briefly discusses the view that behavior may be thought of as a phenotypic adaptation that can be quantitatively studied, and then considered in more detail ways in which predatory animals, especially mammals, satisfy their need for food. Topics covered include predatory behavior, hunting modes, prey selection, hunting success, and others. (JN)

  4. Feeding patterns of migratory and non-migratory fourth instar larvae of two coexisting Chaoborus species in an acidic and metal contaminated lake: Importance of prey ingestion rate in predicting metal bioaccumulation

    USGS Publications Warehouse

    Croteau, M.-N.; Hare, L.; Marcoux, P.

    2003-01-01

    We studied diel variations in the feeding habits and migratory behaviors of two coexisting Chaoborus species in an acidic and metal contaminated lake (Lake Turcotte, QC, Canada). We found that although the zooplankton community was dominated by rotifers, both Chaoborus species fed mostly on chironomids and crustaceans despite the relatively low abundance of these prey types in the lake plankton. Chaoborus americanus larvae fed on those of Chaoborus punctipennis, but not vice versa. The non-migratory species (C. americanus) fed throughout the day and night whereas the migratory species (C. punctipennis) fed only at night while in the water column. The larger-bodied C. americanus consumed more prey and had a more diverse diet than did the smaller-bodied C. punctipennis. Differences in feeding habits between the Chaoborus species inhabiting Lake Turcotte (prey biomass, prey types) likely explain in part their ability to coexist. Attempts to predict Cd in the Chaoborus species using our measurements of Cd in their prey and their prey ingestion rates met with mixed success; although we correctly predicted higher Cd concentrations for C. americanus larvae than for C. punctipennis larvae, we under-predicted absolute Cd concentrations. We suggest that studies such as ours that are based on analyses of gut contents of larvae collected at intervals of 4h or longer likely underestimate prey ingestion rates.

  5. Analysis of a predator-prey system with predator switching.

    PubMed

    Khan, Q J A; Balakrishnan, E; Wake, G C

    2004-01-01

    In this paper, we consider an interaction of prey and predator species where prey species have the ability of group defence. Thresholds, equilibria and stabilities are determined for the system of ordinary differential equations. Taking carrying capacity as a bifurcation parameter, it is shown that a Hopf bifurcation can occur implying that if the carrying capacity is made sufficiently large by enrichment of the environment, the model predicts the eventual extinction of the predator providing strong support for the so-called 'paradox of enrichment'. PMID:14670532

  6. Prey choice and cannibalistic behaviour in the theropod Coelophysis.

    PubMed

    Nesbitt, Sterling J; Turner, Alan H; Erickson, Gregory M; Norell, Mark A

    2006-12-22

    Direct evidence of prey choice in carnivorous dinosaurs is rare in the fossil record. The most celebrated example pertains to purported stomach contents in the carnivorous dinosaur Coelophysis bauri, which besides revealing prey choice, also points to cannibalistic behaviour as being commonplace (Colbert 1989, 1995). Here, we test this hypothesis by conducting the first comprehensive anatomical and histological examination of the famed Coelophysis 'cannibals'. The results unequivocally show that the gut contents derive from early crocodylomorphs rather than juveniles of Coelophysis. These findings suggest that this taxon is not cannibalistic and bring into question the commonality of this behaviour among non-avian dinosaurs. PMID:17148302

  7. Sympatric Masticophis flagellum and Coluber constrictor select vertebrate prey at different levels of taxonomy

    USGS Publications Warehouse

    Halstead, B.J.; Mushinsky, H.R.; McCoy, E.D.

    2008-01-01

    Masticophis flagellum (Coachwhip) and Coluber constrictor (Eastern Racer) are widespread North American snakes with similar foraging modes and habits. Little is known about the selection of prey by either species, and despite their apparently similar foraging habits, comparative studies of the foraging ecology of sympatric M. flagellum and C. constrictor are lacking. We examined the foraging ecology and prey selection of these actively foraging snakes in xeric, open-canopied Florida scrub habitat by defining prey availability separately for each snake to elucidate mechanisms underlying geographic, temporal, and interspecific variation in predator diets. Nineteen percent of M. flagellum and 28% of C. constrictor contained stomach contents, and most snakes contained only one prey item. Mean relative prey mass for both species was less than 10%. Larger C. constrictor consumed larger prey than small individuals, but this relationship disappeared when prey size was scaled to snake size. Masticophis flagellum was selective at the prey category level, and positively selected lizards and mammals; however, within these categories it consumed prey species in proportion to their availability. In contrast, C. constrictor preyed upon prey categories opportunistically, but was selective with regard to species. Specifically, C. constrictor positively selected Hyla femoralis (Pine Woods Treefrog) and negatively selected Bufo querclcus (Oak Toad), B. terrestris (Southern Toad), and Gastrophryne carolinensis (Eastern Narrowmouth Toad). Thus, despite their similar foraging habits, M. flagellum and C. constrictor select different prey and are selective of prey at different levels of taxonomy. ?? 2008 by the American Society of Ichthyologists and Herpetologists.

  8. Increased olfactory search costs change foraging behaviour in an alien mustelid: a precursor to prey switching?

    PubMed

    Price, Catherine J; Banks, Peter B

    2016-09-01

    If generalist predators are to hunt efficiently, they must track the changing costs and benefits of multiple prey types. Decisions to switch from hunting preferred prey to alternate prey have been assumed to be driven by decreasing availability of preferred prey, with less regard for accessibility of alternate prey. Olfactory cues from prey provide information about prey availability and its location, and are exploited by many predators to reduce search costs. We show that stoats Mustela erminea, an alien olfactory predator in New Zealand, are sensitive to the search costs of hunting both their preferred rodent prey (mice) and a less desirable alternate prey (locust). We manipulated search costs for stoats using a novel form of olfactory camouflage of both prey, and found that stoats altered their foraging strategy depending on whether mice were camouflaged or conspicuous, but only when locusts were also camouflaged. Stoats gave up foraging four times more often when both prey were camouflaged, compared to when mice were conspicuous and locusts camouflaged. There were no differences in the foraging strategies used to hunt camouflaged or conspicuous mice when locusts were easy to find. Consequently, camouflaged mice survived longer than conspicuous mice when locusts were hard to find, but not when locusts were easy to find. Our results demonstrate that predators can integrate search costs from multiple prey types when making foraging decisions. Manipulating olfactory search costs to alter foraging strategies offers new methods for understanding the factors that foreshadow prey switching. PMID:27230396

  9. Large orb-webs adapted to maximise total biomass not rare, large prey

    PubMed Central

    Harmer, Aaron M. T.; Clausen, Philip D.; Wroe, Stephen; Madin, Joshua S.

    2015-01-01

    Spider orb-webs are the ultimate anti-ballistic devices, capable of dissipating the relatively massive kinetic energy of flying prey. Increased web size and prey stopping capacity have co-evolved in a number orb-web taxa, but the selective forces driving web size and performance increases are under debate. The rare, large prey hypothesis maintains that the energetic benefits of rare, very large prey are so much greater than the gains from smaller, more common prey that smaller prey are irrelevant for reproduction. Here, we integrate biophysical and ecological data and models to test a major prediction of the rare, large prey hypothesis, that selection should favour webs with increased stopping capacity and that large prey should comprise a significant proportion of prey stopped by a web. We find that larger webs indeed have a greater capacity to stop large prey. However, based on prey ecology, we also find that these large prey make up a tiny fraction of the total biomass (=energy) potentially captured. We conclude that large webs are adapted to stop more total biomass, and that the capacity to stop rare, but very large, prey is an incidental consequence of the longer radial silks that scale with web size. PMID:26374379

  10. Motivating Goal-Directed Behavior Through Introspective Self-Talk: The Role of the Interrogative Form of Simple Future Tense

    PubMed Central

    Senay, Ibrahim; Albarracín, Dolores; Noguchi, Kenji

    2013-01-01

    Although essential for psychology, introspective self-talk has rarely been studied with respect to its effects on behavior. Nevertheless, the interrogative compared with the declarative form of introspective talk may elicit more intrinsically motivated reasons for action, resulting in goal-directed behavior. In Experiment 1, participants were more likely to solve anagrams if they prepared for the task by asking themselves whether they would work on anagrams as opposed to declaring that they would. In the next three experiments, merely writing Will I as opposed to I will as part of an ostensibly unrelated handwriting task produced better anagram-solving performance and stronger intentions to exercise, which suggests that priming the interrogative structure of self-talk is enough to motivate goal-directed behavior. This effect was found to be mediated by the intrinsic motivation for action and moderated by the salience of the word order of the primes. PMID:20424090

  11. Atmospheric Forcing, Sea-Ice Interannual Variability, and Ocean Current Impacts on the Availability of Bowhead Whale Prey Near Barrow, AK

    NASA Astrophysics Data System (ADS)

    Berline, L.; Spitz, Y. H.; Maslowski, W.; Campbell, R. G.; Ashjian, C.

    2006-12-01

    The linkages between bowhead whale distributions, whale prey availability, ocean and ice processes, and atmospheric forcing and interannual environmental variability in the Northern Alaskan Coastal system near Barrow, AK are being explored through biological-physical modeling, field sampling, and retrospective analysis. Complimentary modeling approaches, based on the outputs of a pan-arctic ice-ocean model of 1/12° resolution and forced by realistic air-sea fluxes and wind stress, were employed to analyze the system response to several forcing scenarios typical of the last decade. The influence of extrinsic (Pacific) input of whale prey (euphausiids) to the region was explored. Euphausiids, an important prey of bowhead whales in the fall at Barrow, AK, must have been transported there from the Bering Sea since at present it is believed that they are not endemic. Transport experiments identified potential trajectories and transit times of euphausiids (whale prey) from Bering Strait to Barrow. For euphausiids seeded at the surface, the probability of reaching Barrow was only 1% in 1997 but 10% in 2002. Subsurface seeded euphausiids also traveled faster with the majority reaching Barrow one month earlier in 2002 than in 1997. These differences were due to stronger northward currents in 2002 than in 1997. Dye-tracer experiments identified the pathways and quantity of Pacific Water entering the Chukchi and Beaufort Seas as a proxy for biomass and nutrients. Results are discussed in the context of field observations. Future work will explore intrinsic mechanisms influencing whale prey abundance.

  12. Eight pairs of descending visual neurons in the dragonfly give wing motor centers accurate population vector of prey direction

    PubMed Central

    Gonzalez-Bellido, Paloma T.; Peng, Hanchuan; Yang, Jinzhu; Georgopoulos, Apostolos P.; Olberg, Robert M.

    2013-01-01

    Intercepting a moving object requires prediction of its future location. This complex task has been solved by dragonflies, who intercept their prey in midair with a 95% success rate. In this study, we show that a group of 16 neurons, called target-selective descending neurons (TSDNs), code a population vector that reflects the direction of the target with high accuracy and reliability across 360°. The TSDN spatial (receptive field) and temporal (latency) properties matched the area of the retina where the prey is focused and the reaction time, respectively, during predatory flights. The directional tuning curves and morphological traits (3D tracings) for each TSDN type were consistent among animals, but spike rates were not. Our results emphasize that a successful neural circuit for target tracking and interception can be achieved with few neurons and that in dragonflies this information is relayed from the brain to the wing motor centers in population vector form. PMID:23213224

  13. Sex Differences in Adolescents' Health-Threatening Behaviors: What Accounts for Them? Monitoring the Future. Occasional Paper 23.

    ERIC Educational Resources Information Center

    Herzog, A. Regula; And Others

    Young men are more likely than young women to engage in behaviors that threaten their health, including alcohol and drug use, risky driving, and becoming injured by others. The explanation of these sex differences is the focus of this paper. Findings from nationwide samples of high school seniors are consistent with a model that posits personal…

  14. Encouraging Teens To Adopt a Safe, Healthy Lifestyle: A Foundation for Improving Future Adult Behaviors. Child Trends Research Brief.

    ERIC Educational Resources Information Center

    Hatcher, Juliet L.; Scarpa, Juliet

    By envisioning adolescence as an ideal time to promote good physical health, it is possible to save lives and set in motion a lifetime of good health outcomes. To identify programs that promote health, this brief summarizes experimental studies of health-related behaviors, and reviews more than 230 research studies to identify factors associated…

  15. Rich Global Dynamics in a Prey-Predator Model with Allee Effect and Density Dependent Death Rate of Predator

    NASA Astrophysics Data System (ADS)

    Sen, Moitri; Banerjee, Malay

    In this work we have considered a prey-predator model with strong Allee effect in the prey growth function, Holling type-II functional response and density dependent death rate for predators. It presents a comprehensive study of the complete global dynamics for the considered system. Especially to see the effect of the density dependent death rate of predator on the system behavior, we have presented the two parametric bifurcation diagrams taking it as one of the bifurcation parameters. In course of that we have explored all possible local and global bifurcations that the system could undergo, namely the existence of transcritical bifurcation, saddle node bifurcation, cusp bifurcation, Hopf-bifurcation, Bogdanov-Takens bifurcation and Bautin bifurcation respectively.

  16. Predator-prey interactions between the corallivorous snail Coralliophila abbreviata and the carnivorous deltoid rock snail Thais deltoidea.

    PubMed

    Sharp, William C; Delgado, Gabriel A

    2015-10-01

    Coral reefs in the Florida Keys have become highly degraded in recent decades, prompting efforts to reestablish populations of vital reef-accreting corals to restore reef structure and ecological function. However, predation on these corals by the corallivorous gastropod Coralliophila abbreviata has been a substantial and chronic impediment to these restoration efforts. We conducted laboratory experiments to determine whether Thais deltoidea, a carnivorous gastropod that commonly occurs with C. abbreviata, is a predator of C. abbreviata. We demonstrated that T. deltoidea readily preys upon C. abbreviata and preferentially targets smaller individuals, a foraging behavior that may optimize the energy gained due to reduced handling and consumption times. If this trophic relationship proves ecologically relevant, understanding the predator-prey dynamics between these species could ultimately aid in the development of a comprehensive coral reef restoration strategy for Florida. PMID:26803883

  17. Predator-prey role reversals, juvenile experience and adult antipredator behaviour

    PubMed Central

    Choh, Yasuyuki; Ignacio, Maira; Sabelis, Maurice W.; Janssen, Arne

    2012-01-01

    Although biologists routinely label animals as predators and prey, the ecological role of individuals is often far from clear. There are many examples of role reversals in predators and prey, where adult prey attack vulnerable young predators. This implies that juvenile prey that escape from predation and become adult can kill juvenile predators. We show that such an exposure of juvenile prey to adult predators results in behavioural changes later in life: after becoming adult, these prey killed juvenile predators at a faster rate than prey that had not been exposed. The attacks were specifically aimed at predators of the species to which they had been exposed. This suggests that prey recognize the species of predator to which they were exposed during their juvenile stage. Our results show that juvenile experience affects adult behaviour after a role reversal. PMID:23061011

  18. Scanning Behavior in the Medicinal Leech Hirudo verbana

    PubMed Central

    Harley, Cynthia M.; Wagenaar, Daniel A.

    2014-01-01

    While moving through their environment, medicinal leeches stop periodically and wave their head or body back and forth. This activity has been previously described as two separate behaviors: one called ‘head movement’ and another called ‘body waving’. Here, we report that these behaviors exist on a continuum, and provide a detailed description of what we now call ‘scanning’. Scanning-related behavior has been thought to be involved in orientation; its function has never before been assessed. While previous studies suggested an involvement of scanning in social behavior, or sucker placement, our behavioral studies indicate that scanning is involved in orienting the leech towards prey stimuli. When such stimuli are present, scanning behavior is used to re-orient the leech in the direction of a prey-like stimulus. Scanning, however, occurs whether or not prey is present, but in the presence of prey-like stimuli scanning becomes localized to the stimulus origin. Most likely, this behavior helps the leech to gain a more detailed picture of its prey target. The display of scanning, regardless of the presence or absence of prey stimuli, is suggestive of a behavior that is part of an internally driven motor program, which is not released by the presence of sensory stimuli. The data herein include first steps to understanding the neural mechanisms underlying this important behavior. PMID:24465907

  19. Exposure to "low-level" aggression in school: associations with aggressive behavior, future expectations, and perceived safety.

    PubMed

    Boxer, Paul; Edwards-Leeper, Laura; Goldstein, Sara E; Musher-Eizenman, Dara; Dubow, Eric F

    2003-12-01

    Examined associations with witnessing and being victimized by "low-level" aggressive acts (e.g., pushing, gossip) and three indicators of psychosocial functioning in a sample of 771 elementary school students from one urban and one suburban school district. Results indicated that exposure to low-level aggression appears to relate to psychosocial functioning in ways similar to more severe forms of aggression. Students who were exposed to higher levels of both witnessing and victimization by low-level aggression reported the highest levels of engagement in aggression, the lowest levels of positive expectations for the future, and the lowest levels of perceived safety. Findings are discussed in the context of research on exposure to aggression in general, with suggestions offered for future studies. Implications of the findings for school-based intervention programs are raised. PMID:15109121

  20. Direct identification of predator-prey dynamics in gyrokinetic simulations

    SciTech Connect

    Kobayashi, Sumire Gürcan, Özgür D; Diamond, Patrick H.

    2015-09-15

    The interaction between spontaneously formed zonal flows and small-scale turbulence in nonlinear gyrokinetic simulations is explored in a shearless closed field line geometry. It is found that when clear limit cycle oscillations prevail, the observed turbulent dynamics can be quantitatively captured by a simple Lotka-Volterra type predator-prey model. Fitting the time traces of full gyrokinetic simulations by such a reduced model allows extraction of the model coefficients. Scanning physical plasma parameters, such as collisionality and density gradient, it was observed that the effective growth rates of turbulence (i.e., the prey) remain roughly constant, in spite of the higher and varying level of primary mode linear growth rates. The effective growth rate that was extracted corresponds roughly to the zonal-flow-modified primary mode growth rate. It was also observed that the effective damping of zonal flows (i.e., the predator) in the parameter range, where clear predator-prey dynamics is observed, (i.e., near marginal stability) agrees with the collisional damping expected in these simulations. This implies that the Kelvin-Helmholtz-like instability may be negligible in this range. The results imply that when the tertiary instability plays a role, the dynamics becomes more complex than a simple Lotka-Volterra predator prey.

  1. Testing for Camouflage Using Virtual Prey and Human "Predators"

    ERIC Educational Resources Information Center

    Todd, Peter A.

    2009-01-01

    Camouflage is a prevalent feature of the natural world and as such has a ready appeal to students; however, it is a difficult subject to study using real predators and prey. This paper focuses how one fundamental type of camouflage, disruptive colouration (bold markings that break up the outline of the organism), can be tested using paper…

  2. Does colour polymorphism enhance survival of prey populations?

    PubMed

    Wennersten, Lena; Forsman, Anders

    2009-06-22

    That colour polymorphism may protect prey populations from predation is an old but rarely tested hypothesis. We examine whether colour polymorphic populations of prey exposed to avian predators in an ecologically valid visual context were exposed to increased extinction risk compared with monomorphic populations. We made 2976 artificial pastry prey, resembling Lepidoptera larvae, in four different colours and presented them in 124 monomorphic and 124 tetramorphic populations on tree trunks and branches such that they would be exposed to predation by free-living birds, and monitored their 'survival'. Among monomorphic populations, there was a significant effect of prey coloration on survival, confirming that coloration influenced susceptibility to visually oriented predators. Survival of polymorphic populations was inferior to that of monomorphic green populations, but did not differ significantly from monomorphic brown, yellow or red populations. Differences in survival within polymorphic populations paralleled those seen among monomorphic populations; the red morph most frequently went extinct first and the green morph most frequently survived the longest. Our findings do not support the traditional protective polymorphism hypothesis and are in conflict with those of earlier studies. As a possible explanation to our findings, we offer a competing 'giveaway cue' hypothesis: that polymorphic populations may include one morph that attracts the attention of predators and that polymorphic populations therefore may suffer increased predation compared with some monomorphic populations. PMID:19324729

  3. Direct identification of predator-prey dynamics in gyrokinetic simulations

    NASA Astrophysics Data System (ADS)

    Kobayashi, Sumire; Gürcan, Özgür D.; Diamond, Patrick H.

    2015-09-01

    The interaction between spontaneously formed zonal flows and small-scale turbulence in nonlinear gyrokinetic simulations is explored in a shearless closed field line geometry. It is found that when clear limit cycle oscillations prevail, the observed turbulent dynamics can be quantitatively captured by a simple Lotka-Volterra type predator-prey model. Fitting the time traces of full gyrokinetic simulations by such a reduced model allows extraction of the model coefficients. Scanning physical plasma parameters, such as collisionality and density gradient, it was observed that the effective growth rates of turbulence (i.e., the prey) remain roughly constant, in spite of the higher and varying level of primary mode linear growth rates. The effective growth rate that was extracted corresponds roughly to the zonal-flow-modified primary mode growth rate. It was also observed that the effective damping of zonal flows (i.e., the predator) in the parameter range, where clear predator-prey dynamics is observed, (i.e., near marginal stability) agrees with the collisional damping expected in these simulations. This implies that the Kelvin-Helmholtz-like instability may be negligible in this range. The results imply that when the tertiary instability plays a role, the dynamics becomes more complex than a simple Lotka-Volterra predator prey.

  4. Hydrodynamic effects on a predator approaching a group of preys

    NASA Astrophysics Data System (ADS)

    De Rosis, Alessandro

    2014-11-01

    A numerical approach to predict the hydrodynamics involving a predator approaching a group of 100 preys is presented. A collective behavioural model is adopted to predict the two-dimensional space-time evolution of the predator-preys system that is supposed to be immersed in a fluid. The preys manifest mutual repulsion, attraction and orientation, while the predator is idealized as an individual to be strongly repulsed. During the motion, the predator experiences a resistance induced by the encompassing fluid. Such effect is accounted for by computing the hydrodynamic force and by modifying the predator’s velocity given by the behavioural equations. A numerical campaign is carried out by varying the predator’s drag coefficient. Moreover, analyses characterized by progressively wider predator’s perception areas are performed, thus highlighting the role of the hydrodynamics over the behavioural interactions. In order to estimate the predator’s performance, an ad-hoc parameter is proposed. Moreover, findings in terms of trajectories and angular momentum of the group of preys are discussed. Present findings show that the sole collective behavioural equations are insufficient to predict the performance of a predator that is immersed in a fluid, since its motion is drastically affected by the resistance of the surrounding fluid.

  5. Can the Theory of Planned Behavior predict dietary intention and future dieting in an ethnically diverse sample of overweight and obese veterans attending medical clinics?

    PubMed

    Lash, Denise N; Smith, Jane Ellen; Rinehart, Jenny K

    2016-04-01

    Obesity has become a world-wide epidemic; in the United States (U.S.) approximately two-thirds of adults are classified as overweight or obese. Military veterans' numbers are even higher, with 77% of retired or discharged U.S. veterans falling in these weight categories. One of the most common methods of changing one's weight is through dieting, yet little is known regarding the factors that facilitate successful dieting behavior. The current investigation tested the Theory of Planned Behavior's (TPB) ability to predict dietary intention and future dieting in a sample of 84 overweight and obese patients attending medical clinics at a Veterans Affairs Hospital in the southwestern part of the U.S. Participants primarily were male (92%) and ethnic/racial minorities (58%). Perceived need and anticipated regret were added to the standard TPB model. While the TPB predicted dietary intention, it did not significantly account for improved dietary behaviors. Anticipated regret significantly enhanced the basic TPB's ability to predict intention to diet, while perceived need did not. These findings highlight the difficulty in predicting sustained change in a complex behavior such as dieting to lose weight. The need for more work with older, overweight/obese medical patients attending veterans' facilities is stressed, as is the need for such work with male patients and ethnic minorities in particular. PMID:26792774

  6. Predicting the distributions of predator (snow leopard) and prey (blue sheep) under climate change in the Himalaya.

    PubMed

    Aryal, Achyut; Shrestha, Uttam Babu; Ji, Weihong; Ale, Som B; Shrestha, Sujata; Ingty, Tenzing; Maraseni, Tek; Cockfield, Geoff; Raubenheimer, David

    2016-06-01

    Future climate change is likely to affect distributions of species, disrupt biotic interactions, and cause spatial incongruity of predator-prey habitats. Understanding the impacts of future climate change on species distribution will help in the formulation of conservation policies to reduce the risks of future biodiversity losses. Using a species distribution modeling approach by MaxEnt, we modeled current and future distributions of snow leopard (Panthera uncia) and its common prey, blue sheep (Pseudois nayaur), and observed the changes in niche overlap in the Nepal Himalaya. Annual mean temperature is the major climatic factor responsible for the snow leopard and blue sheep distributions in the energy-deficient environments of high altitudes. Currently, about 15.32% and 15.93% area of the Nepal Himalaya are suitable for snow leopard and blue sheep habitats, respectively. The bioclimatic models show that the current suitable habitats of both snow leopard and blue sheep will be reduced under future climate change. The predicted suitable habitat of the snow leopard is decreased when blue sheep habitats is incorporated in the model. Our climate-only model shows that only 11.64% (17,190 km(2)) area of Nepal is suitable for the snow leopard under current climate and the suitable habitat reduces to 5,435 km(2) (reduced by 24.02%) after incorporating the predicted distribution of blue sheep. The predicted distribution of snow leopard reduces by 14.57% in 2030 and by 21.57% in 2050 when the predicted distribution of blue sheep is included as compared to 1.98% reduction in 2030 and 3.80% reduction in 2050 based on the climate-only model. It is predicted that future climate may alter the predator-prey spatial interaction inducing a lower degree of overlap and a higher degree of mismatch between snow leopard and blue sheep niches. This suggests increased energetic costs of finding preferred prey for snow leopards - a species already facing energetic constraints due to the

  7. Marine predators and persistent prey in the southeast Bering Sea

    NASA Astrophysics Data System (ADS)

    Sigler, Michael F.; Kuletz, Kathy J.; Ressler, Patrick H.; Friday, Nancy A.; Wilson, Christopher D.; Zerbini, Alexandre N.

    2012-06-01

    Predictable prey locations reduce search time and energetic costs of foraging; thus marine predators often exploit locations where prey concentrations persist. In our study, we examined whether this association is influenced by differences among predator species in foraging modes (travel cost, surface feeder or diver) or whether the predator species is a central place forager or not. We examined distributions of two seabird species during their nesting period, the surface-feeding black-legged kittiwake (Rissa tridactyla) and the pursuit-diving thick-billed murre (Uria lomvia), and two baleen whale species, the humpback whale (Megaptera novaeangliae) and the fin whale (Balaenoptera physalus), in relation to two key prey, age-1 walleye pollock (Theragra chalcogramma) and euphausiids (Euphausiidae). Prey surveys were conducted once each year during 2004 and 2006-2010. Concurrent predator surveys were conducted in 2006-2010 (seabirds) and 2008 and 2010 (whales). We compared the seabird and whale foraging locations to where age-1 pollock and euphausiids were concentrated and considered the persistence of these concentrations, where the time-scale of persistence is year (i.e., a comparison among surveys that are conducted once each year). Euphausiids were widespread and concentrations often were reliably found within specific 37 km×37 km blocks ('persistent hot spots of prey'). In contrast, age-1 pollock were more concentrated and their hot spots were persistent only on coarser scales (>37 km). Both seabird species, regardless of foraging mode, were associated with age-1 pollock but not with euphausiids, even though age-1 pollock were less persistent than euphausiids. The higher travel cost central place foragers, thick-billed murres, foraged at prey concentrations nearer their island colonies than black-legged kittiwakes, which were more widespread foragers. Humpback whales were not tied to a central place and mostly were located only where euphausiids were

  8. Future hospital care in a population-based series of twin pairs discordant for physical activity behavior.

    PubMed Central

    Kujala, U M; Kaprio, J; Sarna, S; Koskenvuo, M

    1999-01-01

    OBJECTIVES: This study investigated the association between physical activity behavior and morbidity, taking into account genetic selection. METHODS: Hospitalizations were followed from the beginning of 1977 to the end of 1986 in 710 same-sex healthy twin pairs discordant for leisure-time physical activity and in 151 pairs discordant for all physical activity at base-line in 1975. RESULTS: During the follow-up, among twin pairs discordant for leisure activity, the active member spent, on average, 43% fewer days in the hospital than the inactive member; the corresponding percentage was 55% among pairs discordant for all activity. CONCLUSIONS: Physically inactive behavior is associated with increased need for hospital treatments, even after genetic and other confounding factors are taken into account. PMID:10589321

  9. Relating spatial perspective taking to the perception of other's affordances: providing a foundation for predicting the future behavior of others

    PubMed Central

    Creem-Regehr, Sarah H.; Gagnon, Kyle T.; Geuss, Michael N.; Stefanucci, Jeanine K.

    2013-01-01

    Understanding what another agent can see relates functionally to the understanding of what they can do. We propose that spatial perspective taking and perceiving other's affordances, while two separate spatial processes, together share the common social function of predicting the behavior of others. Perceiving the action capabilities of others allows for a common understanding of how agents may act together. The ability to take another's perspective focuses an understanding of action goals so that more precise understanding of intentions may result. This review presents an analysis of these complementary abilities, both in terms of the frames of reference and the proposed sensorimotor mechanisms involved. Together, we argue for the importance of reconsidering the role of basic spatial processes to explain more complex behaviors. PMID:24068992

  10. Warming reinforces nonconsumptive predator effects on prey growth, physiology, and body stoichiometry.

    PubMed

    Janssens, Lizanne; Van Dievel, Marie; Stoks, Robby

    2015-12-01

    While nonconsumptive effects of predators may strongly affect prey populations, little is known how future warming will modulate these effects. Such information would be especially relevant with regard to prey physiology and resulting changes in prey stoichiometry. We investigated in Enallagma cyathigerum damselfly larvae the effects of a 4°C warming (20°C vs. 24°C) and predation risk on growth rate, physiology and body stoichiometry, for the first time including all key mechanisms suggested by the general stress paradigm (GSP) on how stressors shape changes in body stoichiometry. Growth rate and energy storage were higher at 24°C. Based on thermodynamic principles and the growth rate hypothesis, we could demonstrate predictable reductions in body C:P under warming and link these to the increase in P-rich RNA; the associated warming-induced decrease in C:N may be explained by the increased synthesis of N-rich proteins. Yet, under predation risk, growth rate instead decreased with warming and the warming-induced decreases in C:N and C:P disappeared. As predicted by the GSP, larvae increased body C:N and C:P at 24°C under predation risk. Notably, we did not detect the assumed GSP-mechanisms driving these changes: despite an increased metabolic rate there was neither an increase of C-rich biomolecules (instead fat and sugar contents decreased under predation risk), nor a decrease of N-rich proteins. We hypothesize that the higher C:N and N:P under predation risk are caused by a higher investment in morphological defense. This may also explain the stronger predator-induced increase in C:N under warming. The expected higher C:P under predation risk was only present under warming and matched the observed growth reduction and associated reduction in P-rich RNA. Our integrated mechanistic approach unraveled novel pathways of how warming and predation risk shape body stoichiometry. Key findings that (1) warming effects on elemental stoichiometry were predictable and

  11. Along Came a Spider: Using Live Arthropods in a Predator-Prey Activity

    ERIC Educational Resources Information Center

    Richardson, Matthew L.; Hari, Janice

    2011-01-01

    We developed a predator-prey activity with eighth-grade students in which they used wolf spiders ("Lycosa carolinensis"), house crickets ("Acheta domestica"), and abiotic factors to address how (1) adaptations in predators and prey shape their interaction and (2) abiotic factors modify the interaction between predators and prey. We tested student…

  12. Nonselective Harvesting of a Prey-Predator Fishery with Gompertz Law of Growth

    ERIC Educational Resources Information Center

    Purohit, D.; Chaudhuri, K. S.

    2002-01-01

    This paper develops a mathematical model for the nonselective harvesting of a prey-predator system in which both the prey and the predator obey the Gompertz law of growth and some prey avoid predation by hiding. The steady states of the system are determined, and the dynamical behaviour of both species is examined. The possibility of existence of…

  13. Dietary supplementation with non-prey food enhances fitness of a predatory arthropod

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Uncertainties exist about the value of non-prey food for natural enemies that are commonly food limited, and the dietary conditions where non-prey foods are beneficial for carnivorous species. We examined the nutritional role of a non-prey food using a ground dwelling, tangle web-building spider tha...

  14. Perceptual advertisement by the prey of stalking or ambushing predators.

    PubMed

    Broom, Mark; Ruxton, Graeme D

    2012-12-21

    There has been previous theoretical explorations of the stability of signals by prey that they have detected a stalking or ambush predator, where such perceptual advertisement dissuades the predator from attacking. Here we use a game theoretical model to extend the theory to consider some empirically-motivated complexities: (i) many perceptual advertisement signals appear to have the potential to vary in intensity, (ii) higher intensity signals are likely to be most costly to produce, and (iii) some high-cost signals (such as staring directly at the predator) can only be utilised if the prey is very confident of the existence of a nearby predator (that is, there are reserved or unfakable signals). We demonstrate that these complexities still allow for stable signalling. However, we do not find solutions where prey use a range of signal intensities to signal different degrees of confidence in the proximity of a predator; with prey simply adopting a binary response of not signalling or always signalling at the same fixed level. However this fixed level will not always be the cheapest possible signal, and we predict that prey that require more certainty about proximity of a predator will use higher-cost signals. The availability of reserved signals does not prohibit the stability of signalling based on lower-cost signals, but we also find circumstances where only the reserved signal is used. We discuss the potential to empirically test our model predictions, and to develop theory further to allow perceptual advertisement to be combined with other signalling functions. PMID:22960570

  15. Multimodal cues improve prey localization under complex environmental conditions.

    PubMed

    Rhebergen, F; Taylor, R C; Ryan, M J; Page, R A; Halfwerk, W

    2015-09-01

    Predators often eavesdrop on sexual displays of their prey. These displays can provide multimodal cues that aid predators, but the benefits in attending to them should depend on the environmental sensory conditions under which they forage. We assessed whether bats hunting for frogs use multimodal cues to locate their prey and whether their use varies with ambient conditions. We used a robotic set-up mimicking the sexual display of a male túngara frog (Physalaemus pustulosus) to test prey assessment by fringe-lipped bats (Trachops cirrhosus). These predatory bats primarily use sound of the frog's call to find their prey, but the bats also use echolocation cues returning from the frog's dynamically moving vocal sac. In the first experiment, we show that multimodal cues affect attack behaviour: bats made narrower flank attack angles on multimodal trials compared with unimodal trials during which they could only rely on the sound of the frog. In the second experiment, we explored the bat's use of prey cues in an acoustically more complex environment. Túngara frogs often form mixed-species choruses with other frogs, including the hourglass frog (Dendropsophus ebraccatus). Using a multi-speaker set-up, we tested bat approaches and attacks on the robofrog under three different levels of acoustic complexity: no calling D. ebraccatus males, two calling D. ebraccatus males and five D. ebraccatus males. We found that bats are more directional in their approach to the robofrog when more D. ebraccatus males were calling. Thus, bats seemed to benefit more from multimodal cues when confronted with increased levels of acoustic complexity in their foraging environments. Our data have important consequences for our understanding of the evolution of multimodal sexual displays as they reveal how environmental conditions can alter the natural selection pressures acting on them. PMID:26336176

  16. Multimodal cues improve prey localization under complex environmental conditions

    PubMed Central

    Rhebergen, F.; Taylor, R. C.; Ryan, M. J.; Page, R. A.; Halfwerk, W.

    2015-01-01

    Predators often eavesdrop on sexual displays of their prey. These displays can provide multimodal cues that aid predators, but the benefits in attending to them should depend on the environmental sensory conditions under which they forage. We assessed whether bats hunting for frogs use multimodal cues to locate their prey and whether their use varies with ambient conditions. We used a robotic set-up mimicking the sexual display of a male túngara frog (Physalaemus pustulosus) to test prey assessment by fringe-lipped bats (Trachops cirrhosus). These predatory bats primarily use sound of the frog's call to find their prey, but the bats also use echolocation cues returning from the frog's dynamically moving vocal sac. In the first experiment, we show that multimodal cues affect attack behaviour: bats made narrower flank attack angles on multimodal trials compared with unimodal trials during which they could only rely on the sound of the frog. In the second experiment, we explored the bat's use of prey cues in an acoustically more complex environment. Túngara frogs often form mixed-species choruses with other frogs, including the hourglass frog (Dendropsophus ebraccatus). Using a multi-speaker set-up, we tested bat approaches and attacks on the robofrog under three different levels of acoustic complexity: no calling D. ebraccatus males, two calling D. ebraccatus males and five D. ebraccatus males. We found that bats are more directional in their approach to the robofrog when more D. ebraccatus males were calling. Thus, bats seemed to benefit more from multimodal cues when confronted with increased levels of acoustic complexity in their foraging environments. Our data have important consequences for our understanding of the evolution of multimodal sexual displays as they reveal how environmental conditions can alter the natural selection pressures acting on them. PMID:26336176

  17. Efficient capture of natural history data reveals prey conservatism of cryptic termite predators.

    PubMed

    Gordon, Eric R L; Weirauch, Christiane

    2016-01-01

    Stenophagy, specialization of a clade on a narrow range of taxa, has not been well studied in speciose clades of predators, principally due to the difficulty of obtaining adequate natural history data. The pantropical Salyavatinae (Hemiptera: Reduviidae; 17 genera, 107 species) contains members with enigmatic morphology and specialized behavior for feeding on termites. All Salyavatinae are suspected specialist termite predators; however, existing observations are limited to seven species. Prior analyses indicate that Salyavatinae may be paraphyletic with respect to another subfamily, Sphaeridopinae, also hypothesized to feed on termites. A molecular phylogeny of these putative termite assassins is here constructed using seven loci from 28 species in nine genera and is used in a dating analysis to shed light on the timing of Neotropical colonization by this primarily Old World clade. DNA extracted from gut contents of 50 individuals was assayed using PCR with prey-specific primers.Molecular assays, along with recent photographs and observations, provide substantial evidence that this clade feeds specifically upon termites, documenting 28 new individual associations. Our phylogeny supports a sister group relationship of the Neotropical genus Salyavata with Sphaeridopinae. Termite association data combined with our phylogeny provide evidence of previously unknown prey conservatism among clades of one of the most diverse groups of specialist termite predators. PMID:26314664

  18. Prey pursuit strategy of Japanese horseshoe bats during an in-flight target-selection task.

    PubMed

    Kinoshita, Yuki; Ogata, Daiki; Watanabe, Yoshiaki; Riquimaroux, Hiroshi; Ohta, Tetsuo; Hiryu, Shizuko

    2014-09-01

    The prey pursuit behavior of Japanese horseshoe bats (Rhinolophus ferrumequinum nippon) was investigated by tasking bats during flight with choosing between two tethered fluttering moths. Echolocation pulses were recorded using a telemetry microphone mounted on the bat combined with a 17-channel horizontal microphone array to measure pulse directions. Flight paths of the bat and moths were monitored using two high-speed video cameras. Acoustical measurements of returning echoes from fluttering moths were first collected using an ultrasonic loudspeaker, turning the head direction of the moth relative to the loudspeaker from 0° (front) to 180° (back) in the horizontal plane. The amount of acoustical glints caused by moth fluttering varied with the sound direction, reaching a maximum at 70°-100° in the horizontal plane. In the flight experiment, moths chosen by the bat fluttered within or moved across these angles relative to the bat's pulse direction, which would cause maximum dynamic changes in the frequency and amplitude of acoustical glints during flight. These results suggest that echoes with acoustical glints containing the strongest frequency and amplitude modulations appear to attract bats for prey selection. PMID:24958227

  19. From forager tracks to prey distributions: an application to tuna vessel monitoring systems (VMS).

    PubMed

    Walker, Emily; Rivoirard, Jacques; Gaspar, Philippe; Bez, Nicolas

    2015-04-01

    In the open ocean, movements of migratory fish populations are typically surveyed using tagging methods that are subject to low sample sizes for archive tags, except for a few notable examples, and poor temporal resolution for conventional tags. Alternatively, one can infer patterns of movement of migratory fish by tracking movements of their predators, i.e., fishing vessels, whose navigational systems (e.g., GPS) provide accurate and frequent VMS (vessel monitoring system) records of movement in pursuit of prey. In this paper, we develop a state-space model that infers the foraging activities of fishing vessels from their tracks. Second, we link foraging activities to probabilities of tuna presence. Finally, using multivariate geostatistical interpolation (cokriging) we map the probability of tuna presence together with their estimation variances and produce a time series of indices of abundance. While the segmentation of the trajectories is validated by observers' data, the present VMS-index is compared to catch rate and proved to be useful for management perspectives. The approach reported in this manuscript extends beyond the case study considered. It can be applied to any foragers that engage in an attempt of capture when they see prey and for whom this attempt is linked to a tractable change in behavior. PMID:26214926

  20. Prey fish escape by sensing the bow wave of a predator.

    PubMed

    Stewart, William J; Nair, Arjun; Jiang, Houshuo; McHenry, Matthew J

    2014-12-15

    Prey fish possess a remarkable ability to sense and evade an attack from a larger fish. Despite the importance of these events to the biology of fishes, it remains unclear how sensory cues stimulate an effective evasive maneuver. Here, we show that larval zebrafish (Danio rerio) evade predators using an escape response that is stimulated by the water flow generated by an approaching predator. Measurements of the high-speed responses of larvae in the dark to a robotic predator suggest that larvae respond to the subtle flows in front of the predator using the lateral line system. This flow, known as the bow wave, was visualized and modeled with computational fluid dynamics. According to the predictions of the model, larvae direct their escape away from the side of their body exposed to more rapid flow. This suggests that prey fish use a flow reflex that enables predator evasion by generating a directed maneuver at high speed. These findings demonstrate a sensory-motor mechanism that underlies a behavior that is crucial to the ecology and evolution of fishes. PMID:25520384

  1. The Nutritional Content of Prey Affects the Foraging of a Generalist Arthropod Predator

    PubMed Central

    Schmidt, Jason M.; Sebastian, Peter; Wilder, Shawn M.; Rypstra, Ann L.

    2012-01-01

    While foraging theory predicts that predatory responses should be determined by the energy content and size of prey, it is becoming increasingly clear that carnivores regulate their intake of specific nutrients. We tested the hypothesis that prey nutrient composition and predator nutritional history affects foraging intensity, consumption, and prey selection by the wolf spider, Pardosa milvina. By altering the rearing environment for fruit flies, Drosophila melanogaster, we produced high quality flies containing more nitrogen and protein and less lipid than low quality fruit flies. In one experiment, we quantified the proportion of flies taken and consumption across a range of densities of either high or low quality flies and, in a second experiment, we determined the prey capture and consumption of spiders that had been maintained on contrasting diets prior to testing. In both cases, the proportion of prey captured declined with increasing prey density, which characterizes the Type II functional response that is typical of wolf spiders. Spiders with similar nutritional histories killed similar numbers of each prey type but consumed more of the low quality prey. Spiders provided high quality prey in the weeks prior to testing killed more prey than those on the low quality diet but there was no effect of prior diet on consumption. In the third experiment, spiders were maintained on contrasting diets for three weeks and then allowed to select from a mixture of high and low quality prey. Interestingly, feeding history affected prey preferences: spiders that had been on a low quality diet showed no preference but those on the high quality diet selected high quality flies from the mixture. Our results suggest that, even when prey size and species identity are controlled, the nutritional experience of the predator as well as the specific content of the prey shapes predator-prey interactions. PMID:23145130

  2. In situ measures of foraging success and prey encounter reveal marine habitat-dependent search strategies.

    PubMed

    Thums, Michele; Bradshaw, Corey J A; Hindelli, Mark A

    2011-06-01

    Predators are thought to reduce travel speed and increase turning rate in areas where resources are relatively more abundant, a behavior termed "area-restricted search." However, evidence for this is rare, and few empirical data exist for large predators. Animals exhibiting foraging site fidelity could also be spatially aware of suitable feeding areas based on prior experience; changes in movement patterns might therefore arise from the anticipation of higher prey density. We tested the hypothesis that regions of area-restricted search were associated with a higher number of daily speed spikes (a proxy for potential prey encounter rate) and foraging success in southern elephant seals (Mirounga leonina), a species exhibiting both area-restricted searches and high interannual foraging site fidelity. We used onshore morphological measurements and diving data from archival tags deployed during winter foraging trips. Foraging success was inferred from in situ changes in relative lipid content derived from measured changes in buoyancy, and first-passage time analysis was used to identify area-restricted search behavior. Seals exhibited relatively direct southerly movement on average, with intensive search behavior predominantly located at the distal end of tracks. The probability of being in search mode was positively related to changes in relative lipid content; thus, intensively searched areas were associated with the highest foraging success. However, there was high foraging success during the outward transit even though seals moved through quickly without slowing down and increasing turning rate to exploit these areas. In addition, the probability of being in search mode was negatively related to the number of daily speed spikes. These results suggest that movement patterns represent a response to prior expectation of the location of predictable and profitable resources. Shelf habitat was 4-9 times more profitable than the other habitats, emphasizing the importance

  3. Species diversity and predation strategies in a multiple species predator-prey model

    NASA Astrophysics Data System (ADS)

    Mullan, Rory; Glass, David H.; McCartney, Mark

    2015-08-01

    A single predator, single prey ecological model, in which the behaviour of the populations relies upon two control parameters has been expanded to allow for multiple predators and prey to occupy the ecosystem. The diversity of the ecosystem that develops as the model runs is analysed by assessing how many predator or prey species survive. Predation strategies that dictate how the predators distribute their efforts across the prey are introduced in this multiple species model. The paper analyses various predation strategies and highlights their effect on the survival of the predators and prey species.

  4. Stability analysis and numerical simulation of 1 prey - 2 predator system

    NASA Astrophysics Data System (ADS)

    Savitri, D.; Abadi

    2015-03-01

    In this paper, we study an ecological system that consists of 1 prey and 2 predators populations. The prey population grows logistically while Holling type II functional response is applied for both predators . The first predator preys on the prey and the second predator preys on the first one. The study starts with the stability analysis of critical points of the systems. Then, by using normal form and centre manifold method the information about other nontrivial solutions due to bifurcation including possible limit cycles appearance is obtained. The results are confirmed by numerical simulation using MatCont and biological interpretation of the results is also presented.

  5. Switching from simple to complex dynamics in a predator-prey-parasite model: An interplay between infection rate and incubation delay.

    PubMed

    Bairagi, N; Adak, D

    2016-07-01

    Parasites play a significant role in trophic interactions and can regulate both predator and prey populations. Mathematical models might be of great use in predicting different system dynamics because models have the potential to predict the system response due to different changes in system parameters. In this paper, we study a predator-prey-parasite (PPP) system where prey population is infected by some micro parasites and predator-prey interaction occurs following Leslie-Gower model with type II response function. Infection spreads following SI type epidemic model with standard incidence rate. The infection process is not instantaneous but mediated by a fixed incubation delay. We study the stability and instability of the endemic equilibrium point of the delay-induced PPP system with respect to two parameters, viz., the force of infection and the length of incubation delay under two cases: (i) the corresponding non-delayed system is stable and (ii) the corresponding non-delayed system is unstable. In the first case, the system populations coexist in stable state for all values of delay if the force of infection is low; or show oscillatory behavior when the force of infection is intermediate and the length of delay crosses some critical value. The system, however, exhibits very complicated dynamics if the force of infection is high, where the system is unstable in absence of delay. In this last case, the system shows oscillatory, stable or chaotic behavior depending on the length of delay. PMID:27091744

  6. Sabretoothed carnivores and the killing of large prey.

    PubMed

    Andersson, Ki; Norman, David; Werdelin, Lars

    2011-01-01

    Sabre-like canines clearly have the potential to inflict grievous wounds leading to massive blood loss and rapid death. Hypotheses concerning sabretooth killing modes include attack to soft parts such as the belly or throat, where biting deep is essential to generate strikes reaching major blood vessels. Sabretoothed carnivorans are widely interpreted as hunters of larger and more powerful prey than that of their present-day nonsabretoothed relatives. However, the precise functional advantage of the sabretooth bite, particularly in relation to prey size, is unknown. Here, we present a new point-to-point bite model and show that, for sabretooths, depth of the killing bite decreases dramatically with increasing prey size. The extended gape of sabretooths only results in considerable increase in bite depth when biting into prey with a radius of less than ∼10 cm. For sabretooths, this size-reversed functional advantage suggests predation on species within a similar size range to those attacked by present-day carnivorans, rather than "megaherbivores" as previously believed. The development of the sabretooth condition appears to represent a shift in function and killing behaviour, rather than one in predator-prey relations. Furthermore, our results demonstrate how sabretoothed carnivorans are likely to have evolved along a functionally continuous trajectory: beginning as an extension of a jaw-powered killing bite, as adopted by present-day pantherine cats, followed by neck-powered biting and thereafter shifting to neck-powered shear-biting. We anticipate this new insight to be a starting point for detailed study of the evolution of pathways that encompass extreme specialisation, for example, understanding how neck-powered biting shifts into shear-biting and its significance for predator-prey interactions. We also expect that our model for point-to-point biting and bite depth estimations will yield new insights into the behaviours of a broad range of extinct predators

  7. Rattlesnake strike behavior: kinematics

    PubMed

    Kardong; v

    1998-03-01

    The predatory behavior of rattlesnakes includes many distinctive preparatory phases leading to an extremely rapid strike, during which venom is injected. The rodent prey is then rapidly released, removing the snake's head from retaliation by the prey. The quick action of the venom makes possible the recovery of the dispatched prey during the ensuing poststrike period. The strike is usually completed in less than 0.5 s, placing a premium on an accurate strike that produces no significant errors in fang placement that could result in poor envenomation and subsequent loss of the prey. To clarify the basis for effective strike performance, we examined the basic kinematics of the rapid strike using high-speed film analysis. We scored numerous strike variables. Four major results were obtained. (1) Neurosensory control of the strike is based primarily upon sensory inputs via the eyes and facial pits to launch the strike, and upon tactile stimuli after contact. Correction for errors in targeting occurs not by a change in strike trajectory, but by fang repositioning after the jaws have made contact with the prey. (2) The rattlesnake strike is based upon great versatility and variation in recruitment of body segments and body postures. (3) Forces generated during acceleration of the head are transferred to posterior body sections to decelerate the head before contact with the prey, thereby reducing impact forces upon the snake's jaws. (4) Body acceleration is based on two patterns of body displacement, one in which acute sections of the body open like a gate, the other in which body segments flow around postural curves similar to movements seen during locomotion. There is one major implication of these results: recruitment of body segments, launch postures and kinematic features of the strike may be quite varied from strike to strike, but the overall predatory success of each strike by a rattlesnake is very consistent.

    PMID:9464964

  8. Prey preferences of the snow leopard (Panthera uncia): regional diet specificity holds global significance for conservation.

    PubMed

    Lyngdoh, Salvador; Shrotriya, Shivam; Goyal, Surendra P; Clements, Hayley; Hayward, Matthew W; Habib, Bilal

    2014-01-01

    The endangered snow leopard is a large felid that is distributed over 1.83 million km(2) globally. Throughout its range it relies on a limited number of prey species in some of the most inhospitable landscapes on the planet where high rates of human persecution exist for both predator and prey. We reviewed 14 published and 11 unpublished studies pertaining to snow leopard diet throughout its range. We calculated prey consumption in terms of frequency of occurrence and biomass consumed based on 1696 analysed scats from throughout the snow leopard's range. Prey biomass consumed was calculated based on the Ackerman's linear correction factor. We identified four distinct physiographic and snow leopard prey type zones, using cluster analysis that had unique prey assemblages and had key prey characteristics which supported snow leopard occurrence there. Levin's index showed the snow leopard had a specialized dietary niche breadth. The main prey of the snow leopard were Siberian ibex (Capra sibrica), blue sheep (Pseudois nayaur), Himalayan tahr (Hemitragus jemlahicus), argali (Ovis ammon) and marmots (Marmota spp). The significantly preferred prey species of snow leopard weighed 55±5 kg, while the preferred prey weight range of snow leopard was 36-76 kg with a significant preference for Siberian ibex and blue sheep. Our meta-analysis identified critical dietary resources for snow leopards throughout their distribution and illustrates the importance of understanding regional variation in species ecology; particularly prey species that have global implications for conservation. PMID:24533080

  9. Predicting predation through prey ontogeny using size-dependent functional response models.

    PubMed

    McCoy, Michael W; Bolker, Benjamin M; Warkentin, Karen M; Vonesh, James R

    2011-06-01

    The functional response is a critical link between consumer and resource dynamics, describing how a consumer's feeding rate varies with prey density. Functional response models often assume homogenous prey size and size-independent feeding rates. However, variation in prey size due to ontogeny and competition is ubiquitous, and predation rates are often size dependent. Thus, functional responses that ignore prey size may not effectively predict predation rates through ontogeny or in heterogeneous populations. Here, we use short-term response-surface experiments and statistical modeling to develop and test prey size-dependent functional responses for water bugs and dragonfly larvae feeding on red-eyed treefrog tadpoles. We then extend these models through simulations to predict mortality through time for growing prey. Both conventional and size-dependent functional response models predicted average overall mortality in short-term mixed-cohort experiments, but only the size-dependent models accurately captured how mortality was spread across sizes. As a result, simulations that extrapolated these results through prey ontogeny showed that differences in size-specific mortality are compounded as prey grow, causing predictions from conventional and size-dependent functional response models to diverge dramatically through time. Our results highlight the importance of incorporating prey size when modeling consumer-prey dynamics in size-structured, growing prey populations. PMID:21597252

  10. Sensory-based niche partitioning in a multiple predator - multiple prey community.

    PubMed

    Falk, Jay J; ter Hofstede, Hannah M; Jones, Patricia L; Dixon, Marjorie M; Faure, Paul A; Kalko, Elisabeth K V; Page, Rachel A

    2015-06-01

    Many predators and parasites eavesdrop on the communication signals of their prey. Eavesdropping is typically studied as dyadic predator-prey species interactions; yet in nature, most predators target multiple prey species and most prey must evade multiple predator species. The impact of predator communities on prey signal evolution is not well understood. Predators could converge in their preferences for conspicuous signal properties, generating competition among predators and natural selection on particular prey signal features. Alternatively, predator species could vary in their preferences for prey signal properties, resulting in sensory-based niche partitioning of prey resources. In the Neotropics, many substrate-gleaning bats use the mate-attraction songs of male katydids to locate them as prey. We studied mechanisms of niche partitioning in four substrate-gleaning bat species and found they are similar in morphology, echolocation signal design and prey-handling ability, but each species preferred different acoustic features of male song in 12 s