Gulls and Plovers: The Ecology and Behaviour of Mixed~Species Feeding Groups PDF
Preview Gulls and Plovers: The Ecology and Behaviour of Mixed~Species Feeding Groups
Gulls and Plovers Studies in Behavioural Adaptation Series Editor: John Lazarus, Department of Psychology, The University of Newcastle-upon-Tyne Gulls and Plovers: The Ecology and Behaviour ofM ixed Species Feeding Groups C.J. Barnard and D.B.A. Thompson In preparation: Modelling in Behavioural Ecology Dennis Lendrem Motivation and Decision-making in Animals Robin McCleery GULLSAND PLOVERS The Ecology and Behaviour of Mixed-Species Feeding Groups C.]. BARNARD, Department of Zoology, University of Nottingham and D.B.A. THOMPSON, Department of Zoology, University of Liverpool CROOM HELM London & Sydney © 1985 c.]. Barnard and D.B.A. Thompson Softcover reprint of the hardcover 1s t edition 1985 Croom Helm Ltd, Provident House, Burrell Row, Beckenham, Kent BR3 1AT Croom Helm Australia Pty Ltd, Suite 4, 6th Floor, 64-76 Kippax Street, Surry Hills, NSW 2010, Australia British Library Cataloguing in Publication Data Barnard, c.]. Gulls and plovers: the ecology and behaviour of mixed species feeding groups.-(Croom Helm studies in behavioural adaptation) 1. Gulls-Food 2. Plovers-Food 3. Birds -Food 1. Title II. Thompson, D.B.A. 598'.3 QL696.C46 ISBN-13: 978-94-010-8652-3 e-TSBN-13: 978-94-009-4864-8 DOT: 10.1007/978-94-009-4864-8 Typeset in Plantin by Leaper & Gard Ltd, Bristol, England Contents Series Editor's Foreword Vll Preface x Chapter 1. Why Feed in Flocks? 1 Chapter 2. Gulls and Plovers 46 Chapter 3. Choosing Where to Feed: Choice of Field 66 Chapter 4. Choosing Where to Feed: Choice within Fields 93 Chapter 5. Choosing What to Eat 116 Chapter 6. Time Budgeting and Feeding Efficiency 143 Chapter 7. Flock Dynamics: Patterns of Arrival and Departure 192 Chapter 8. Kleptoparasitism: Host and Prey Selection by Gulls 217 Chapter 9. Vigilance, Alarm Responses and an Early Warning 255 System Chapter 10. Gulls and Plovers: an Overview 275 References 280 Index 296 v For Dawn and Anna, Lucy and Matthew Series Editor's Foreword In the early years of this century a Scottish doctor speculated on the evolutionary origin of human tears. It seemed to him that with the increase in brain size and cognitive powers of our early ancestors many events in the struggle for existence would be just too distressing to observe. How comforting then, for the mother, distraught by the sight of her child being devoured by a lion, to cloud her vision with a flood of tears! Just so, though if the good doctor had pondered further, the following picture might have occurred to him, comfortable in his speculative armchair, and given him some pause for thought. ~.... ~' ~.. ~ ..•.. u" .. , ~- .' _ ....... vii viii SERIES EDITOR'S FOREWORD These stories do not, of course, get us very far in understanding the evolution of tears or anything else, but they do remind us how far the study of behavioural adaptation has come this century. This is, in fact, an exciting time for students of behaviour. The last twenty years have seen a great advance in the theoretical armoury for tackling questions of behavioural evolution and adaptation, and a parallel expansion in empirical studies, particularly in the field. The concepts of inclusive fitness and the evolutionarily stable strategy, for example, have helped to explain major features of social behaviour and have generated entirely new questions and predictions for the field worker to examine. Cost-benefit analysis and optimisation theory have done the same for behaviour in general, and links with population biology and population genetics are becoming stronger. The heady days which saw the birth of behavioural ecology and sociobiology are now over, the new concepts have been refined and consolidated, and field data and comparative studies have accumulated at an impressive rate. Now seems a good time to take stock, to review the state of the art, and to point some directions for future work. These are the aims of the present series, which will examine questions of behavioural adaptation and evolution in depth. As for our intended readership, we hope that all those interested in such problems, from advanced undergraduate to research worker and lecturer, will find these books of value. Some contributions to the series will encompass particular areas of study, reviewing theory and data and presenting fresh ideas. Others will report the findings of new empirical studies of an extensive nature, which make a sig nificant contribution by examining a range of interrelated questions. The rich ness, but also the difficulty, of functional enquiry results from the multiple effects of selection pressures and the complex causal relationships between the behavioural responses to evolutionary forces. Studies which measure a compre hensive set of related behavioural attributes, and their ecological correlates, are therefore particularly valuable. The present book describes just such a study. Chris Barnard and Desmond Thompson show how the feeding requirements of three interacting species of birds influence their social lives in a variety ofc omplex and subtle ways. Chapter by chapter they build a story in which foraging demands are seen to determine not only where the birds feed and what they feed on, but also their time budgets and flock dynamics, while flock structure, in turn, is shown to have important effects on the foraging strategy. They achieve this by integrating two areas of behavioural ecology that have until now remained largely independent: foraging theory and group living. In addition, they describe a number of intra-and inter specific tactics for feeding competition and the early warning of predatory approach; particularly striking are the ingenious manoeuvres adopted by two of the species to thwart the food stealing attempts of the third. Barnard and Thompson's method has been to start with the basic questions of foraging theory and flock dynamics, and then to develop and test a series of new hypotheses in order to gain a more complete understanding of the system. In this way they generate a quite extraordinary amount of data and reveal an SERIES EDITOR'S FOREWORD IX unsuspected subtlety and sensitivity in the individual's behavioural solutions to the moment-to-moment problems of feeding in a social context. Their work demonstrates at once both the intellectual allure of evolutionary studies and the daunting complexity in nature that remains to be explained. John Lazarus Department of Psychology University of N ewcastle-upon-Tyne Preface Since its advent in the 1960s, behavioural ecology (the synthesis of ethology, population ecology and evolutionary theory) has revolutionised our understand ing of the evolution of behaviour. Until recently, however, models specific to certain aspects of behavioural ecology have been proposed and tested largely in isolation. Models of foraging behaviour, for instance, have been developed mainly without regard for the complex social environment in which many pre dators feed. Conversely, models of social behaviour have not catered for the changes in foraging criteria which may be imposed on predators as a conse quence of their social organisation. With increasingly detailed laboratory and field studies, however, it is now possible to integrate different aspects of the behavioural ecology of certain species, and assess their role in determining individual survivorship and reproductive potential. This book examines the rela tionship between individual foraging behaviour and group dynamics in a mixed species feeding association. It shows how consideration of adaptive behaviour at the level of the individual can lead to testable predictions about the formati{)n of feeding groups. A major point emerging from the book is that the consequences of mixed association for the individual may not only be very different from those of associating with conspecifics, but that, even within particular associations, they may depend on the size and species composition of the group. The book focuses on a winter feeding association between three charadrii form bird species, lapwings (Vanellus vanellus), golden plovers (Pluvialis apricaria) and black-headed gulls (Lams ridibundus), which we have studied on agricultural land for the past six years. The association is based on feeding flocks oflapwings which are exploited by golden plovers as indicators of the best places to start feeding. Lapwings also provide local information within the flock on the x
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