Theory states that an optimal forager should exploit a patch so long as its harvest rate of resou... more Theory states that an optimal forager should exploit a patch so long as its harvest rate of resources from the patch exceeds its energetic, predation, and missed opportunity costs for foraging. However, for many foragers, predation is not the only source of danger they face while foraging. Foragers also face the risk of injuring themselves. To test whether risk of injury gives rise to a foraging cost, we offered red foxes pairs of depletable resource patches in which they experienced diminishing returns. The resource patches were identical in all respects, save for the risk of injury. In response, the foxes exploited the safe patches more intensively. They foraged for a longer time and also removed more food (i.e., had lower giving up densities) in the safe patches compared to the risky patches. Although they never sustained injury, video footage revealed that the foxes used greater care while foraging from the risky patches and removed food at a slower rate. Furthermore, an increas...
Conservation behavior is a relatively new interdisciplinary field aimed at investigating how prox... more Conservation behavior is a relatively new interdisciplinary field aimed at investigating how proximate and ultimate aspects of animal behavior can be of value in preventing the loss of biodiversity. This new discipline’s usefulness in promoting practical conservation-matters is subject to debate, with some scientists arguing that the importance of behavior in conservation practice is overemphasized. Here, we propose a conceptual model that identifies the key linkages between animal behavior and conserva-tion biology. The model is a simply structured, hierarchical, and parsimonious framework that will help bridge the gap between the 2 disciplines and establish a common ground on which the field of conservation behavior can evolve and from which paradigms can be developed. Key words: adaptive behavior, behavior-based management, behavioral indicators, conceptual model, conservation behavior. [Behav Ecol 22:236–239 (2011)] Although the disciplines of animal behavior and conservationbio...
In heterogenous environments, predation risk from multiple predators and the availability of reso... more In heterogenous environments, predation risk from multiple predators and the availability of resources fluctuate both spatially and temporally. The various predators may include both aerial and terrestrial species that can facilitate each other and present qualitatively different risks to prey. Animals therefore forage across a complex landscape of fear, with areas of risks and relative safety where resources are generally asymmetrically distributed. Therefore, a trade-off exists between remaining safe and locating food. Animals make foraging decisions regarding where, when and for how long to forage by titrating marginal costs and benefits of foraging within and the marginal value of foraging across depletable resource patches. We conducted a series of titration experiments to determine how Allenby’s gerbils (Gerbillus andersoni allenbyi) titrated food and safety when presented with predation risk from owls, vipers and the joint risk from both predators. We manipulated bush and open microhabitats by increasing food availability in the riskier patches. In response to the different levels of enrichment, gerbils titrated food and safety. Riskier open microhabitats needed to be four times as rich in food as bush patches to be of equal value when subjected to predation from owls and the joint risk from owls and vipers. In response to vipers alone, riskier bush patches needed to be 2–4 times as rich in food as safer open patches for the marginal value of foraging to equalize across microhabitats. Overall, predation risk from owls and the joint risk from owls and vipers resulted in the greatest foraging costs for gerbils in risky microhabitats. Thus, the combined overall risk from multiple predator species was equivalent to the risk presented by the gerbils’ most dangerous predator (owls alone). Animals trade-off remaining safe with locating food by titrating the marginal costs and benefits of foraging. We assessed how foragers titrate these costs and benefits through behavioural titration experiments. In our study, gerbils titrated food and safety in response to owls and vipers, aerial and terrestrial predators known to facilitate one another. Riskier patches needed to be 2–4 times as rich in food as safer patches to be of equal value to foraging gerbils. From the gerbils’ perspective, owls are more formidable predators than vipers; despite the facilitation that occurs between these predators, the combination of the two predators had little effect on the titration beyond that of the owls alone. Behavioural titrations are important for quantifying differences in foraging costs between microhabitats and in response to multiple predators with different hunting strategies. As single-predator systems are relatively rare, titration experiments provide the opportunity to gain insights into the foraging/safety trade-offs made by animals in response to multiple predators on the landscape.
Page 1. OIKOS 67: 548-556. Copenhagen 1993 Mechanisms of species coexistence of optimal foragers:... more Page 1. OIKOS 67: 548-556. Copenhagen 1993 Mechanisms of species coexistence of optimal foragers: temporal partitioning by two species of sand dune gerbils Burt P. Kotler, Joel S. Brown and Aziz Subach Kotler, BP, Brown, JS and Subach, A. 1993. ...
Background: Predator and prey engage in a behavioural game in which the behavioural decision of o... more Background: Predator and prey engage in a behavioural game in which the behavioural decision of one affects that of the other. Behavioural games can be influenced by differential predation risk caused by habitat patchiness in the environment. Patches may provide prey with a differential risk of predation due to the size of area that provides refuge. The predator has to respond to the existence of patches with varying degrees of predation risk because this variable affects the time they spend foraging in each patch. Question: Will the predator and the prey respond optimally to each other in a behavioural game? Methods: We conducted behavioural experiments in two identical aviaries (7 m diameter), each with three separate pools (1.52 m diameter, 0.60 m deep, ∼1000 litres capacity). Each pool had two habitats, one a horizontal cover in the centre of the pool (the refuge), the other open water (the risky patch). We used little egrets (one per experiment) and goldfish (15 fish per pool) ...
Theory states that an optimal forager should exploit a patch so long as its harvest rate of resou... more Theory states that an optimal forager should exploit a patch so long as its harvest rate of resources from the patch exceeds its energetic, predation, and missed opportunity costs for foraging. However, for many foragers, predation is not the only source of danger they face while foraging. Foragers also face the risk of injuring themselves. To test whether risk of injury gives rise to a foraging cost, we offered red foxes pairs of depletable resource patches in which they experienced diminishing returns. The resource patches were identical in all respects, save for the risk of injury. In response, the foxes exploited the safe patches more intensively. They foraged for a longer time and also removed more food (i.e., had lower giving up densities) in the safe patches compared to the risky patches. Although they never sustained injury, video footage revealed that the foxes used greater care while foraging from the risky patches and removed food at a slower rate. Furthermore, an increas...
Conservation behavior is a relatively new interdisciplinary field aimed at investigating how prox... more Conservation behavior is a relatively new interdisciplinary field aimed at investigating how proximate and ultimate aspects of animal behavior can be of value in preventing the loss of biodiversity. This new discipline’s usefulness in promoting practical conservation-matters is subject to debate, with some scientists arguing that the importance of behavior in conservation practice is overemphasized. Here, we propose a conceptual model that identifies the key linkages between animal behavior and conserva-tion biology. The model is a simply structured, hierarchical, and parsimonious framework that will help bridge the gap between the 2 disciplines and establish a common ground on which the field of conservation behavior can evolve and from which paradigms can be developed. Key words: adaptive behavior, behavior-based management, behavioral indicators, conceptual model, conservation behavior. [Behav Ecol 22:236–239 (2011)] Although the disciplines of animal behavior and conservationbio...
In heterogenous environments, predation risk from multiple predators and the availability of reso... more In heterogenous environments, predation risk from multiple predators and the availability of resources fluctuate both spatially and temporally. The various predators may include both aerial and terrestrial species that can facilitate each other and present qualitatively different risks to prey. Animals therefore forage across a complex landscape of fear, with areas of risks and relative safety where resources are generally asymmetrically distributed. Therefore, a trade-off exists between remaining safe and locating food. Animals make foraging decisions regarding where, when and for how long to forage by titrating marginal costs and benefits of foraging within and the marginal value of foraging across depletable resource patches. We conducted a series of titration experiments to determine how Allenby’s gerbils (Gerbillus andersoni allenbyi) titrated food and safety when presented with predation risk from owls, vipers and the joint risk from both predators. We manipulated bush and open microhabitats by increasing food availability in the riskier patches. In response to the different levels of enrichment, gerbils titrated food and safety. Riskier open microhabitats needed to be four times as rich in food as bush patches to be of equal value when subjected to predation from owls and the joint risk from owls and vipers. In response to vipers alone, riskier bush patches needed to be 2–4 times as rich in food as safer open patches for the marginal value of foraging to equalize across microhabitats. Overall, predation risk from owls and the joint risk from owls and vipers resulted in the greatest foraging costs for gerbils in risky microhabitats. Thus, the combined overall risk from multiple predator species was equivalent to the risk presented by the gerbils’ most dangerous predator (owls alone). Animals trade-off remaining safe with locating food by titrating the marginal costs and benefits of foraging. We assessed how foragers titrate these costs and benefits through behavioural titration experiments. In our study, gerbils titrated food and safety in response to owls and vipers, aerial and terrestrial predators known to facilitate one another. Riskier patches needed to be 2–4 times as rich in food as safer patches to be of equal value to foraging gerbils. From the gerbils’ perspective, owls are more formidable predators than vipers; despite the facilitation that occurs between these predators, the combination of the two predators had little effect on the titration beyond that of the owls alone. Behavioural titrations are important for quantifying differences in foraging costs between microhabitats and in response to multiple predators with different hunting strategies. As single-predator systems are relatively rare, titration experiments provide the opportunity to gain insights into the foraging/safety trade-offs made by animals in response to multiple predators on the landscape.
Page 1. OIKOS 67: 548-556. Copenhagen 1993 Mechanisms of species coexistence of optimal foragers:... more Page 1. OIKOS 67: 548-556. Copenhagen 1993 Mechanisms of species coexistence of optimal foragers: temporal partitioning by two species of sand dune gerbils Burt P. Kotler, Joel S. Brown and Aziz Subach Kotler, BP, Brown, JS and Subach, A. 1993. ...
Background: Predator and prey engage in a behavioural game in which the behavioural decision of o... more Background: Predator and prey engage in a behavioural game in which the behavioural decision of one affects that of the other. Behavioural games can be influenced by differential predation risk caused by habitat patchiness in the environment. Patches may provide prey with a differential risk of predation due to the size of area that provides refuge. The predator has to respond to the existence of patches with varying degrees of predation risk because this variable affects the time they spend foraging in each patch. Question: Will the predator and the prey respond optimally to each other in a behavioural game? Methods: We conducted behavioural experiments in two identical aviaries (7 m diameter), each with three separate pools (1.52 m diameter, 0.60 m deep, ∼1000 litres capacity). Each pool had two habitats, one a horizontal cover in the centre of the pool (the refuge), the other open water (the risky patch). We used little egrets (one per experiment) and goldfish (15 fish per pool) ...
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