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Why Animals Live in Groups
Many of our encounters with animals in the wild involve groups. Familiar examples of groups include schools of herring in the ocean, murders of crows in the city and herds of wildebeests in the African savannah. Why animals live in groups has been a hotly debated topic for animal behaviour students for many years. Indeed, living in groups must have provided advantages to individuals during evolution to compensate for obvious disadvantages such as having to share resources with others. The devil is in understanding how a balance is struck for each species between the costs and the benefits of living in groups.
I became interested in studying the evolution of sociality early in my career as a scientist studying animal behaviour. I now pursue this research in the field with semipalmated sandpipers, a small species of shorebirds, whose flocks are often enormous in size as the above photo attests. The study of group living can be approached from many angles, from mathematical modelling to comparative analyses of a large number of species and observational studies in the field. This broad scope really appealed to me, and I have tried over the years to use these different approaches to better understand why animals live in groups rather than alone when gathering resources. I recently wrote a book, called Social Predation, to synthesize the large literature on how living in groups can benefit both predators and prey. The book provides insight as to how individuals benefit from living in groups and how sociality can evolve in a large range of species from insects to birds and mammals.
Research on foraging for predators and prey was originally developed with solitary species in mind. This is understandable given the complexities involved in predicting the behaviour of even a single animal. Social foraging theory emerged later from the need to apply similar concepts to species foraging in groups. It has become increasingly clear that what happens when predators and prey forage in groups cannot be easily deduced from what we know about solitary foragers. For instance, hunting in groups may allow predators to catch larger prey but at the cost of having to share each meal. These costs and benefits may not simply increase linearly with the size of a group but vary in a complex, often surprising fashion. As another example, consider the simple fact that if a predator can capture only one member of a group during an attack, the impetus for a prey animal may be to outrun its companions rather than the predator. Such new perspectives require new approaches since the best course of action for a predator or a prey may also depend on the behaviour of group members.
I propose the term social predation to capture the complexities of finding prey and avoiding predation in groups. In the book, I explore the ways group living can benefit predators and prey as well as the potential disadvantages that may accrue. Endlessly fascinating, the study of group living is sure to remain at the forefront of animal behaviour research for many years to come, and it is my hope that this book will maintain interest in this topic and stimulate further research.
About the Author
Guy Beauchamp is a behavioural ecologist specializing on social foraging in birds. He has written over 100 articles in peer-reviewed journals. He has been studying sandpipers for the last 10 years. He currently works as a research officer at the Veterinary College of the University of Montréal, Québec, Canada.
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