SONGS, ROARS, AND RITUALS LESLEY J. ROGERS AND GISELA KAPLAN COMMUNICATION IN BIRDS, MAMMALS, AND OTHER ANIMALS HARVARD UNIVERSITY PRESS' CAMBRIDGE, MASSACHUSETTS Copyright © 1998,2000 by Lesley J. Rogers and Gisela Kaplan All rights reserved Printed in the United States of America Second printing, 2002 First Harvard University Press paperback edition, 2002 An earlier version of this book was published in 1998 by Allen & Unwin as Not Only Roars and Rituals: Communication in Animals Drawings by Tina Wilson Library of Congress Cataloging-in-Publication Data Rogers, Lesley J. Songs, roars, and rituals: communication in birds, mammals, and other animals I Lesley J. Rogers and Gisela Kaplan. p.cm. Rev. ed. of: Not only roars and rituals. 1998. Includes bibliographical references (p. ). ISBN 0-674-00058-7 (cloth) ISBN 0-674-00827-8 (pbk.) 1. Animal communication. I. Kaplan, Gisela. II. Rogers, Lesley J. Not only roars and rituals. III. Title. QL776 .R64 2000 591.59-dc21 00-025602 1~ tIw ~ oI11fdtf, a c&t dpedd to- Id ~ all ~ CONTENTS PREFACE IX ()tte WHAT IS COMMUNICATION? 1U1{j- SIGNALS AND SENSORY PERCEPTION 26 1kee IS SIGNALING INTENTIONAL OR UNINTENTIONAL? 48 q()'{'u COMMUNICATION IN BIRDS 70 qw.e COMMUNICATION IN MAMMALS 100 $h LEARNING TO COMMUNICATE 128 $ett.eft THE EVOLUTION OF COMMUNICATION 150 t«t/d HUMAN-ANIMAL CONTACTS 169 REFERENCES 185 INDEX 201 FIGURES 1 . 1 Sending and receiving a signal 3 1.2 Flight-intention postures and displays 16 1. 3 Threat postures 18 1.4 Feather ruffling in a galah 23 2.1 Sound spectrograms of butcherbird songs 30 2.2 Sound spectrograms of noisy calls 31 2.3 Sound spectrograms of the alarm calls of chickens 43 2.4 Open-mouth play-threat display of an orangutan 47 4.1 Postures of the tawny frogmouth 78 4.2 Mimicry of human speech by a galah 82 4.3 The antiphonal song of two Australian magpie larks 90 4.4 Mimicry of a kookaburra by a magpie 97 5.1 Genital display of a marmoset 102 5.2 Facial displays of orangutans 104 5.3 Facial displays of marmosets 105 5.4 Vocalizations of marmosets 113 6.1 The sensitive period for song learning 134 6.2 Song tutors 137 6.3 Mimicry of a human voice by a seal 141 6.4 Developmental changes in the wrr calls of vervet monkeys 146 PREFACE It is reasonable to ask at the beginning of this book why communication in animals interests us. What can knowledge of animal communication achieve, both in terms of understanding our own environment and in terms of our ethical position toward the natural world? Researching animal behavior is a humbling experience. It shows how little we know about the hundreds of thousands of species that inhabit the globe and how little we know of the ways in which they communicate within and between species. How exciting it is when we think that per­ haps we may have cracked another part of a code in this enormously large world of secret codes. We are constantly discovering more about the complex capabilities of animals. No one can help being impressed by the wealth of social subtle­ ties and complexities that individual species display. In the songs, roars, and rituals they perform, we begin to see meaning. Here is our personal wonder, pleasure, and excitement in studying animal communication. These are qualities that ultimately sustain the most enduring inquiries. We also know only too well that new knowledge of animal behavior is needed urgently. Many species are tumbling into extinction because of direct human intervention and human mistreatment of the precious leg­ acy of the natural world. In some cases, we do not even know why. In oth­ ers, we know why, but have found few acceptable ways of coexisting with other species. Instead, we have deprived them of habitat and conditions they need to survive. Some of that mistreatment, exploitation, or coercive control may in part be based on ignorance. As the social philosopher Hannah Arendt once said, most people who "do evil do not intend to do evil." The rate of extinction of species shows that we are doing evil and, ironically, in so many instances we are doing this while actually proclaim­ ing our liking for animals. We harm them even by assuming that they x PREFACE must like, react to, and be comfortable with the same things that satisfy us. This is often far from the case. Only in the twentieth century have we humans truly begun to understand that the existence of animals and their well-being is tied to ours. In turn, our well-being, at least partly, is dependent on their being allowed to maintain their lives. In this introduction to animal communication, we attempt to provide a sympathetic but scientifically well-founded argument about a set of complex behaviors in animals. We have considered a broad range of com­ municative patterns in mammals and birds, and even in frogs and other species. One focus in this book is on learning to communicate so as to suggest to the reader, and to remind ourselves, that we still need to free our thinking from the legacy of Descartes and his view that the capacities of animals are purely mechanistic. One of the aims of this book, then, is to suggest that many animals are sensitive to what they do and to what we may do to them. Many may suffer at our hands and many are doomed to slide into extinction unless we can learn to respect animals in ways that leave them unfettered space to lead their lives. Although this is an intro­ ductory book on the broad issues of communication in animals, we hope very much that it is a book to be enjoyed as much by the general reader as by the student of ethology and by colleagues in the field, offering some special morsels and giving a portrait of animals consistent with our view that animals matter a great deal. Many of the ideas that form the backbone of this book were refined in valuable discussions with our colleagues and friends, Professors Michael Cullen, Judith Blackshaw, Richard Andrew, Peter Slater, Jeannette Ward, Dietmar Todt, Allen and the late Beatrix Gardner, and also Drs. Christo­ pher Evans, Patrice Adret, Michelle Hook-Costigan, and Jim Scanlan. We are also most grateful to our anonymous reader for Harvard University Press for excellent suggestions and to our editors Michael Fisher and Nancy Clemente. SONGS, ROARS, AND RITUALS WHAT IS COMMUNICATION? A large flock of galahs, Australian cockatoos, is feeding on grain scattered on newly plowed soil. Hundreds of white crests, though flattened, are dis­ tinctly visible against the birds' bright pink breasts and the background. Each bird maintains a characteristic social distance from the others and the hundreds of bowed yet bobbing heads suggest complete attention to feeding-until, catching sight of an approaching farmer, one bird raises its crest and screeches. At this signal of alarm the flock takes to the air as if the decision to do so were instantaneous. A signal has been sent and its meaning interpreted reliably by each member of the flock. Communica­ tion has occurred. An enormous elephant seal lumbers up the beach, head raised, snort­ ing as he threatens a rival. The animals make aggressive lunges at each other, blood is drawn, and, with growling sounds, a truce is reached. One seal bows his head and moves away. Victor and loser have communi­ cated on a matter of disputed territory and partner ownership has been decided. These are grand spectacles of communication, but intimate and close­ range contact has its own forms of more subtle communication. A mother orangutan cradles her baby of seven days on her chest as she hangs by all four limbs. She smiles, as a human might do, and the infant glances up at her. A bond has formed between mother and infant and is maintained by communication. As these examples show, communication in animals can take many forms, and before we explore such, it is important to have a working definition of what we mean by communication in a more general sense. There are many different definitions of communication and they vary with the field in which the researcher is working. When referring to com­ munication in humans, psychologists often restrict the concept to acts 2 WHAT IS COMMUNICATION? that we perform with the intention of altering the behavior of another person. Linguists, however, are prepared to use a broader definition of communication to include the gestures and facial expressions that we make quite unintentionally while speaking. Since the person receiving these signals perceives and interprets both the intentional and uninten­ tional signals, they feel it is important to include both types of signaling in discussions of communication in humans. There is no question that a large amount of communication among humans is intentional, but much unintentional signaling takes place as well. For example, in many cultures, someone giving a friendly greeting to another person raises his or her eyebrows for a moment. This facial gesture is called "eyebrow flashing." Unless we make a conscious effort to think about it, we are not aware of having performed an eyebrow flash. Even the receiver may not be aware of having seen the eyebrow flash, despite the fact that it is a very important aspect of the greeting and alters the receiver's interpretation of the words spoken at the time. As Irenaus Eibl-Eibesfeldt (1972) has demonstrated, greetings made without the eyebrow flash are interpreted as less friendly even when the spoken words are identical.