We are pleased to present the first collection dedicated to highlighting the research of our Editorial Board, entitled Editors' Showcase: Foraging and Antipredator Behavior. This exclusive collection is open to Editorial Board members only and will feature high-quality contributions from our Associate and Review Editors. Specialty Chief Editor Professor Rulon Clark leads this initiative which will focus on new insights, novel developments, current challenges, latest discoveries, recent advances, and future perspectives in the field of Foraging and Antipredator Behavior. The work presented here celebrates the broad diversity of research performed across the section and aims to put a spotlight on all areas of interest to our Editors. This collection aims to further support Frontiers’ strong community by recognizing and promoting the work of highly deserving Editors.

San Diego State University

Frontiers in Ethology

Foraging and Antipredator Behavior

Editors' Showcase: Foraging and Antipredator Behavior

Shorebirds are iconic examples of food resource partitioning through use of contrasted morphological structures to acquire food. Differences in beak lengths and shapes allow species catching their food at various sediment depths. Contrasted leg lengths allow species foraging at distinct water depths. Despite these morphological differences, shorebirds use a small number of stereotyped behaviors for food acquisition. We classify these behaviors by analyzing video sequences of ca. two dozen species of Western Palearctic shorebirds, during migration or wintering. We suggest disassembling food acquisition in three successive stages: foraging, feeding, and swallowing. The foraging stage regroups the locomotion behaviors associated to food detection, and the behaviors used during food capture. The feeding stage encompasses the handling behaviors used to kill or stun the prey and to extract its edible parts, and the behaviors used to transport the prey from the distal part of the beak to the bird’s pharynx. In the swallowing stage, the edible parts of the prey enter the pharynx. We show that three of these behaviors (locomotion, capture and transport) are made up of stereotypical, mutually exclusive components, and can be considered as performances. Each of our study species use one or maximum two components of these three performances. Overall, our study provides insights on interspecific variation in shorebird food acquisition behaviors that we put in a phylogenetic perspective. We confirm the long-standing hypothesis that pecking is the plesiomorphic behavior of food capture, and we show that those locomotion and transport behaviors associated with pecking differ from those associated with derived capture behaviors, leading to a syndrome of food acquisition behaviors in shorebirds.

Shorebirds are iconic examples of food resource partitioning through use of contrasted morphological structures to acquire food. Differences in beak lengths and shapes allow species catching their food at various sediment depths. Contrasted leg lengths allow species foraging at distinct water depths. Despite these morphological differences, shorebirds use a small number of stereotyped behaviors for food acquisition. We classify these behaviors by analyzing video sequences of ca. two dozen species of Western Palearctic shorebirds, during migration or wintering. We suggest disassembling food acquisition in three successive stages: foraging, feeding, and swallowing. The foraging stage regroups the locomotion behaviors associated to food detection, and the behaviors used during food capture. The feeding stage encompasses the handling behaviors used to kill or stun the prey and to extract its edible parts, and the behaviors used to transport the prey from the distal part of the beak to the bird&#x2019;s pharynx. In the swallowing stage, the edible parts of the prey enter the pharynx. We show that three of these behaviors (locomotion, capture and transport) are made up of stereotypical, mutually exclusive components, and can be considered as performances. Each of our study species use one or maximum two components of these three performances. Overall, our study provides insights on interspecific variation in shorebird food acquisition behaviors that we put in a phylogenetic perspective. We confirm the long-standing hypothesis that pecking is the plesiomorphic behavior of food capture, and we show that those locomotion and transport behaviors associated with pecking differ from those associated with derived capture behaviors, leading to a syndrome of food acquisition behaviors in shorebirds.

Repertoire of food acquisition behaviors in Western Palearctic shorebirds (Aves, Charadriiformes)

Grand challenges in foraging behavior and predator-prey interactions: next generation ethology in the Anthropocene

We describe a natural situation that supports predictions of theoretical scenarios in which predators tactically influence the food - safety trade-off faced by prey to increase their vulnerability. By using low-cost ‘false attacks’ or otherwise advertising their presence, predators force prey to spend time in refuges or in other forms of safety-enhancing behavior, during which foraging is impaired or impossible. Prey must compensate by taking extra risks at other times or places to meet their energy requirements, and as a consequence become easier to capture. We used data on the occurrence of over-ocean flocking (OOF) by Pacific dunlins (Calidris alpina pacifica), and on the timing and success of attacks by peregrines. OOF is a safe but energetically expensive alternative to traditional roosting, and largely replaced the latter in Boundary Bay of southwest British Columbia as the presence of wintering peregrines rose during the 1990s. Peregrines appear to use ‘false’ or ‘non-serious’ attacks to shift the occurrence of OOF to a tidal time frame earlier than is ideal for dunlins, thereby creating later hunting opportunities during which dunlins were vulnerable than otherwise would have been the case. The shift increased dunlin mortality substantially. Tactics used by predators such as prominent perching, salient signals and unpredictable appearances, could have evolved because this forces prey to increase their level of caution, rendering them more vulnerable at other times or places.

We describe a natural situation that supports predictions of theoretical scenarios in which predators tactically influence the food - safety trade-off faced by prey to increase their vulnerability. By using low-cost ‘false attacks’ or otherwise advertising their presence, predators force prey to spend time in refuges or in other forms of safety-enhancing behavior, during which foraging is impaired or impossible. Prey must compensate by taking extra risks at other times or places to meet their energy requirements, and as a consequence become easier to capture. We used data on the occurrence of over-ocean flocking (OOF) by Pacific dunlins (Calidris alpina pacifica), and on the timing and success of attacks by peregrines. OOF is a safe but energetically expensive alternative to traditional roosting, and largely replaced the latter in Boundary Bay of southwest British Columbia as the presence of wintering peregrines rose during the 1990s. Peregrines appear to use ‘false’ or ‘non-serious’ attacks to shift the occurrence of OOF to a tidal time frame earlier than is ideal for dunlins, thereby creating later hunting opportunities during which dunlins were vulnerable than otherwise would have been the case. The shift increased dunlin mortality substantially. Tactics used by predators such as prominent perching, salient signals and unpredictable appearances, could have evolved because this forces prey to increase their level of caution, rendering them more vulnerable at other times or places.

Gaming the system: how predators induce prey to make themselves more vulnerable

Due to its unforgiving nature, predation pressure exerts strong selection pressure on the behaviour of prey animals. As a result, prey are forced to balance the conflicting demands of successfully detecting and avoiding predators and the need to engage in other fitness-related activities such as foraging, mating and social behaviour. Here, we provide an overview of the role that individual predator avoidance decisions plays in constraining behavioural phenotypes and how past experience with risks shapes current (and future) trade-offs, physiological and life history investments. Critically, access to reliable risk assessment information allows prey to respond to spatially and temporally variable predation risks. Uncertainty of predation risks is expected to limit the ability of prey to make short- and longer-term adjustments responses to predation threats, potentially increasing the indirect costs of predation. We describe a ‘landscape of information’ in which prey rely on publicly available risk assessment information to reduce the uncertainty of predation risks associated with variable threats and the potential impact of natural and anthropogenic environmental factors which may limit information availability. Despite a long tradition of research into the antipredator trade-offs made by prey animals, there remain a number of important unanswered questions.

Due to its unforgiving nature, predation pressure exerts strong selection pressure on the behaviour of prey animals. As a result, prey are forced to balance the conflicting demands of successfully detecting and avoiding predators and the need to engage in other fitness-related activities such as foraging, mating and social behaviour. Here, we provide an overview of the role that individual predator avoidance decisions plays in constraining behavioural phenotypes and how past experience with risks shapes current (and future) trade-offs, physiological and life history investments. Critically, access to reliable risk assessment information allows prey to respond to spatially and temporally variable predation risks. Uncertainty of predation risks is expected to limit the ability of prey to make short- and longer-term adjustments responses to predation threats, potentially increasing the indirect costs of predation. We describe a &#x2018;landscape of information&#x2019; in which prey rely on publicly available risk assessment information to reduce the uncertainty of predation risks associated with variable threats and the potential impact of natural and anthropogenic environmental factors which may limit information availability. Despite a long tradition of research into the antipredator trade-offs made by prey animals, there remain a number of important unanswered questions.

Ecological uncertainty and antipredator behaviour: an integrative perspective

IntroductionPredators can affect prey not only by killing them, but also by causing them to alter their behavior, including patterns of habitat selection. Prey can reduce the risk of predation by moving to habitats where predators are less likely to detect them, less likely to attack, or less likely to succeed. The interaction of such responses to risk with other ecological processes remains relatively unstudied, but in some cases, changes in habitat use to avoid predation may be constrained by competition: larger, dominant competitors should respond freely to predation risk, but the responses of smaller, subordinate competitors may be constrained by the responses of dominant competitors. For large grazing herbivores, an alternative hypothesis proposes that smaller prey species are vulnerable to more predators, and thus should respond more strongly to predation risk.</sec>MethodsHere, we tested these two hypotheses with 775 observations of habitat selection by four species of obligate grazers (zebra, wildebeest, puku and oribi) in the immediate presence or absence of four large carnivores (lion, spotted hyena, African wild dog and cheetah) in three ecosystems (Greater Liuwa, Greater Kafue and Luangwa Valley). Patterns of predation within this set were described by observation of 1,105 kills.</sec>ResultsOur results support the hypothesis that responses to predation risk are strongest for larger, dominant competitors. Even though zebras were killed least often, they showed the strongest shift into cover when carnivores were present. Wildebeest, puku and oribi showed weaker habitat shifts, even though they were more frequently killed. These patterns remained consistent in models that controlled for differences in the hunting mode of the predator (stalking, coursing, or intermediate) and for differences among ecosystems. There was no evidence that smaller species were subject to predation by a broader set of predators. Instead, smaller prey were killed often by smaller predators, and larger prey were killed often by larger predators.</sec>DiscussionBroadly, our results show that responses to predation risk interact with interspecific competition. Accounting for such interactions should help to explain the considerable variation in the strength of responses to predation risk that has been observed.</sec>

Introduction: Predators can affect prey not only by killing them, but also by causing them to alter their behavior, including patterns of habitat selection. Prey can reduce the risk of predation by moving to habitats where predators are less likely to detect them, less likely to attack, or less likely to succeed. The interaction of such responses to risk with other ecological processes remains relatively unstudied, but in some cases, changes in habitat use to avoid predation may be constrained by competition: larger, dominant competitors should respond freely to predation risk, but the responses of smaller, subordinate competitors may be constrained by the responses of dominant competitors. For large grazing herbivores, an alternative hypothesis proposes that smaller prey species are vulnerable to more predators, and thus should respond more strongly to predation risk.Methods: Here, we tested these two hypotheses with 775 observations of habitat selection by four species of obligate grazers (zebra, wildebeest, puku and oribi) in the immediate presence or absence of four large carnivores (lion, spotted hyena, African wild dog and cheetah) in three ecosystems (Greater Liuwa, Greater Kafue and Luangwa Valley). Patterns of predation within this set were described by observation of 1,105 kills.Results: Our results support the hypothesis that responses to predation risk are strongest for larger, dominant competitors. Even though zebras were killed least often, they showed the strongest shift into cover when carnivores were present. Wildebeest, puku and oribi showed weaker habitat shifts, even though they were more frequently killed. These patterns remained consistent in models that controlled for differences in the hunting mode of the predator (stalking, coursing, or intermediate) and for differences among ecosystems. There was no evidence that smaller species were subject to predation by a broader set of predators. Instead, smaller prey were killed often by smaller predators, and larger prey were killed often by larger predators.Discussion: Broadly, our results show that responses to predation risk interact with interspecific competition. Accounting for such interactions should help to explain the considerable variation in the strength of responses to predation risk that has been observed.