Why Feed in Flocks

Abstract

In one way, this book is about three species of bird feeding on some fields in Nottinghamshire. In another, it is about the interaction between ecology, social behaviour and predation. That a study of the former can lead to conclusions about the latter is a reflection of the recent, dramatic increase in our understanding of the evolution of animal behaviour, an increase which stems from an integration of ideas from population biology, evolutionary theory and ethology. Behavioural ecology, as the new synthetic approach has become known, seeks to interpret the evolution of behaviour in terms of the constraints imposed and opportunities provided by an animal’s ecology. It assumes that variation in behaviour has a genetic basis and that natural selection is the principal agent governing the differential survival of variants. This simple assumption allows precise, quantitative questions to be asked about the evolution of behaviour in any particular context: How many types of prey should a predator take? How many conspecifics should it associate with? How long should a male court a female before attempting to copulate? The answers are couched in terms of changes in the animal’s reproductive potential as a consequence of its choice from a range of feasible alternatives. The strength of this approach lies in its broad applicability. The same assumptions and methods of analysis underlie the study of parent-offspring relationships in baboons and of choice of prey by foraging water boatmen.