Numerous studies have reported functional improvements in collective behaviour with increasing gr... more Numerous studies have reported functional improvements in collective behaviour with increasing group size, however, the possibility that such improvements may saturate or even decline as group size continues to grow have seldom been tested experimentally. Here, we tested the ability of solitary three-spined sticklebacks and those in groups, ranging from 2 to 29 fish, to leave an unfavourable patch of habitat. Our results replicate the findings of previous studies at low group sizes, with the fish initially showing a reduction in their latency to leave the unfavourable habitat as group size increased. As group size continued to increase, however, latency to leave the habitat increased, so that the functional relationship between group size and latency to depart was U-shaped. Our results suggest an optimum group size in this context of between 12 and 20 fish. Underlying this group-level trend was a similar U-shaped relationship between group size and the first fish to leave the habita...
The earliest studies of collective animal behaviour were inspired by and conducted in the wild. O... more The earliest studies of collective animal behaviour were inspired by and conducted in the wild. Over the past decades much of the research in this field has shifted to the laboratory, combining high-resolution tracking of individuals with mathematical simulations or agent-based models. Today we are beginning to see a 're-wilding' of collective behaviour thanks to technological advances, providing researchers with the opportunity to quantify and model the heterogeneity that exists within the social groupings they study and within the environments in which these groups live. The perspective we present here aims to inspire and steer this research toward answering fundamental and outstanding behavioural and ecological questions, while also tackling pertinent conservation challenges.
Local specialization can be advantageous for individuals and may increase the resilience of the s... more Local specialization can be advantageous for individuals and may increase the resilience of the species to environmental change. However, there may be trade-offs between morphological responses and physiological performance and behaviour. Our aim was to test whether habitat-specific morphology of stickleback (Gasterosteus aculeatus) interacts with physiological performance and behaviour at different salinities. We rejected the hypothesis that deeper body shape of fish from habitats with high predation pressure led to decreases in locomotor performance. However, there was a trade-off between deeper body shape and muscle quality. Muscle of deeper-bodied fish produced less force than that of shallow-bodied saltmarsh fish. Nonetheless, saltmarsh fish had lower swimming performance, presumably because of lower muscle mass overall coupled with smaller caudal peduncles and larger heads. Saltmarsh fish performed better in saline water (20 ppt) relative to freshwater and relative to fish fro...
Multi-species groups are common throughout the animal kingdom and have attracted particular atten... more Multi-species groups are common throughout the animal kingdom and have attracted particular attention in the study of bird flocks, fish schools and ungulate herds (Krause & Ruxton, 2002). A number of functions have been proposed for the evolution of multi-species associations which include increased protection from predators and access to novel food sources (Krause & Ruxton, 2002). The mechanisms of multi-species grouping, however, have received comparatively little attention. In the present study the importance of ...
The exceptional reactivity of animal collectives to predatory attacks is thought to be owing to r... more The exceptional reactivity of animal collectives to predatory attacks is thought to be owing to rapid, but local, transfer of information between group members. These groups turn together in unison and produce escape waves. However, it is not clear how escape waves are created from local interactions, nor is it understood how these patterns are shaped by natural selection. By startling schools of fish with a simulated attack in an experimental arena, we demonstrate that changes in the direction and speed by a small percentage of individuals that detect the danger initiate an escape wave. This escape wave consists of a densely packed band of individuals that causes other school members to change direction. In the majority of cases, this wave passes through the entire group. We use a simulation model to demonstrate that this mechanism can, through local interactions alone, produce arbitrarily large escape waves. In the model, when we set the group density to that seen in real fish sch...
Krause, J., Ward, AJW, James, R. and Croft, D., 2008. Group-living and social networks. In: Magnh... more Krause, J., Ward, AJW, James, R. and Croft, D., 2008. Group-living and social networks. In: Magnhagen, C., Braithwaite, VA, Forsgren, E. and Kapoor, BG, eds. Fish Behaviour. Science Publishers, pp. 485-498. ... This repository does not currently have the full-text of this item. You may be able to access a copy if URLs are provided below. ... Krause, J., Ward, AJW, James, R. and Croft, D.
Predators attack and plants defend, so herbivores face the dilemma of how to eat enough without b... more Predators attack and plants defend, so herbivores face the dilemma of how to eat enough without being eaten. But do differences in the personality of herbivores affect the foraging choices of individuals? We explored the ecological impact of personality in a generalist herbivore, the brushtail possum (Trichosurus vulpecula). After quantifying personality traits in wild individuals brought temporarily into captivity, we tested how these traits altered foraging by individuals when free-ranging in their natural habitat. To measure their responses to the dual costs of predation risk and plant toxin, we varied the toxin concentration of food in safe foraging patches against paired, non-toxic risky patches, and used a novel synthesis of a manipulative Giving-Up-Density (GUD) experiment and video behavioural analysis. At the population level, the cost of safe patches pivoted around that of risky patches depending on food toxin concentration. At the individual level, boldness affected foraging at risky high-quality food patches (as behavioural differences between bold and shy), and at safe patches only when food toxin concentration was low (as differences in foraging outcome). Our results ecologically validate the personality trait of boldness, in brushtail possums. They also reveal, for the first time, a nuanced link between personality and the way in which individuals balance the costs of food and fear. Importantly, they suggest that high plant defence effectively attenuates differences in foraging behaviour arising from variation in personality, but poorly defended plants in safe areas should be differentially subject to herbivory depending on the personality of the herbivore.
Population-level patterns of social organisation are determined by localised interactions between... more Population-level patterns of social organisation are determined by localised interactions between conspecifics. Therefore, understanding the decision rules employed by individuals in these interactions is central to our understanding of species ecology. Research has shown that fishes are not equally socially attracted or aggressive towards all other conspecifics. For example, the preferential association of salmonids with relatives (and reduced aggression towards them) is now well established and, more recently, evidence ...
Numerous studies have reported functional improvements in collective behaviour with increasing gr... more Numerous studies have reported functional improvements in collective behaviour with increasing group size, however, the possibility that such improvements may saturate or even decline as group size continues to grow have seldom been tested experimentally. Here, we tested the ability of solitary three-spined sticklebacks and those in groups, ranging from 2 to 29 fish, to leave an unfavourable patch of habitat. Our results replicate the findings of previous studies at low group sizes, with the fish initially showing a reduction in their latency to leave the unfavourable habitat as group size increased. As group size continued to increase, however, latency to leave the habitat increased, so that the functional relationship between group size and latency to depart was U-shaped. Our results suggest an optimum group size in this context of between 12 and 20 fish. Underlying this group-level trend was a similar U-shaped relationship between group size and the first fish to leave the habita...
The earliest studies of collective animal behaviour were inspired by and conducted in the wild. O... more The earliest studies of collective animal behaviour were inspired by and conducted in the wild. Over the past decades much of the research in this field has shifted to the laboratory, combining high-resolution tracking of individuals with mathematical simulations or agent-based models. Today we are beginning to see a 're-wilding' of collective behaviour thanks to technological advances, providing researchers with the opportunity to quantify and model the heterogeneity that exists within the social groupings they study and within the environments in which these groups live. The perspective we present here aims to inspire and steer this research toward answering fundamental and outstanding behavioural and ecological questions, while also tackling pertinent conservation challenges.
Local specialization can be advantageous for individuals and may increase the resilience of the s... more Local specialization can be advantageous for individuals and may increase the resilience of the species to environmental change. However, there may be trade-offs between morphological responses and physiological performance and behaviour. Our aim was to test whether habitat-specific morphology of stickleback (Gasterosteus aculeatus) interacts with physiological performance and behaviour at different salinities. We rejected the hypothesis that deeper body shape of fish from habitats with high predation pressure led to decreases in locomotor performance. However, there was a trade-off between deeper body shape and muscle quality. Muscle of deeper-bodied fish produced less force than that of shallow-bodied saltmarsh fish. Nonetheless, saltmarsh fish had lower swimming performance, presumably because of lower muscle mass overall coupled with smaller caudal peduncles and larger heads. Saltmarsh fish performed better in saline water (20 ppt) relative to freshwater and relative to fish fro...
Multi-species groups are common throughout the animal kingdom and have attracted particular atten... more Multi-species groups are common throughout the animal kingdom and have attracted particular attention in the study of bird flocks, fish schools and ungulate herds (Krause & Ruxton, 2002). A number of functions have been proposed for the evolution of multi-species associations which include increased protection from predators and access to novel food sources (Krause & Ruxton, 2002). The mechanisms of multi-species grouping, however, have received comparatively little attention. In the present study the importance of ...
The exceptional reactivity of animal collectives to predatory attacks is thought to be owing to r... more The exceptional reactivity of animal collectives to predatory attacks is thought to be owing to rapid, but local, transfer of information between group members. These groups turn together in unison and produce escape waves. However, it is not clear how escape waves are created from local interactions, nor is it understood how these patterns are shaped by natural selection. By startling schools of fish with a simulated attack in an experimental arena, we demonstrate that changes in the direction and speed by a small percentage of individuals that detect the danger initiate an escape wave. This escape wave consists of a densely packed band of individuals that causes other school members to change direction. In the majority of cases, this wave passes through the entire group. We use a simulation model to demonstrate that this mechanism can, through local interactions alone, produce arbitrarily large escape waves. In the model, when we set the group density to that seen in real fish sch...
Krause, J., Ward, AJW, James, R. and Croft, D., 2008. Group-living and social networks. In: Magnh... more Krause, J., Ward, AJW, James, R. and Croft, D., 2008. Group-living and social networks. In: Magnhagen, C., Braithwaite, VA, Forsgren, E. and Kapoor, BG, eds. Fish Behaviour. Science Publishers, pp. 485-498. ... This repository does not currently have the full-text of this item. You may be able to access a copy if URLs are provided below. ... Krause, J., Ward, AJW, James, R. and Croft, D.
Predators attack and plants defend, so herbivores face the dilemma of how to eat enough without b... more Predators attack and plants defend, so herbivores face the dilemma of how to eat enough without being eaten. But do differences in the personality of herbivores affect the foraging choices of individuals? We explored the ecological impact of personality in a generalist herbivore, the brushtail possum (Trichosurus vulpecula). After quantifying personality traits in wild individuals brought temporarily into captivity, we tested how these traits altered foraging by individuals when free-ranging in their natural habitat. To measure their responses to the dual costs of predation risk and plant toxin, we varied the toxin concentration of food in safe foraging patches against paired, non-toxic risky patches, and used a novel synthesis of a manipulative Giving-Up-Density (GUD) experiment and video behavioural analysis. At the population level, the cost of safe patches pivoted around that of risky patches depending on food toxin concentration. At the individual level, boldness affected foraging at risky high-quality food patches (as behavioural differences between bold and shy), and at safe patches only when food toxin concentration was low (as differences in foraging outcome). Our results ecologically validate the personality trait of boldness, in brushtail possums. They also reveal, for the first time, a nuanced link between personality and the way in which individuals balance the costs of food and fear. Importantly, they suggest that high plant defence effectively attenuates differences in foraging behaviour arising from variation in personality, but poorly defended plants in safe areas should be differentially subject to herbivory depending on the personality of the herbivore.
Population-level patterns of social organisation are determined by localised interactions between... more Population-level patterns of social organisation are determined by localised interactions between conspecifics. Therefore, understanding the decision rules employed by individuals in these interactions is central to our understanding of species ecology. Research has shown that fishes are not equally socially attracted or aggressive towards all other conspecifics. For example, the preferential association of salmonids with relatives (and reduced aggression towards them) is now well established and, more recently, evidence ...
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