Bird Senses. Graham R. Martin

      

BIRD SENSES

      BIRD SENSES

      How and What Birds See, Hear, Smell, Taste, and Feel

      GRAHAM R. MARTIN

      PELAGIC PUBLISHING

      Published by Pelagic Publishing

      PO Box 874

      Exeter

      EX3 9BR

      UK

       www.pelagicpublishing.com

       Bird Senses: How and What Birds See, Hear, Smell, Taste, and Feel

      ISBN 978-1-78427-216-6Paperback

      ISBN 978-1-78427-217-3ePub

      ISBN 978-1-78427-218-0PDF

      © Graham R. Martin 2020

      The moral rights of the author have been asserted.

      All rights reserved. Apart from short excerpts for use in research or for reviews, no part of this document may be printed or reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, now known or hereafter invented or otherwise without prior permission from the publisher.

      A CIP record for this book is available from the British Library

      Cover: Great Grey owl (Strix nebulosa) taking off from the ground, Finland, April. © Danny Green/naturepl.com

      For Amber, Bryher, Josie, and Ted

      Contents

Preface

A note on bird taxonomy and bird names

Acknowledgements

1. Senses and sensory ecology

2. Investigating senses

3. Vision in birds: the basics

       4. Bird eyes: variations and consequences

       5. Visual fields

       6. Beyond vision: hearing and smell

       7. The intimate senses: touch and taste

       8. Sensing the earth’s magnetic field

       9. Birds in the dark

       10. Other birds of the night: parrots to passerines

       11. Birds underwater

       12. A sideways look through birds’ eyes

       Appendix: Visual acuity in birds

       Further reading

       Index

Preface

      This book’s aim is to take the reader deep into the world of birds. We may think we know the world of birds through our own senses. But we are just one species, and we are not birds! To get into the world of birds we must go beyond the habitat or ecological points of view. It is necessary also to take a sensory perspective. It is a perspective that leads to an understanding of the different kinds of information that birds have available to them as they live out their lives beside us.

      This is a ‘through birds’ eyes’ approach to ornithology – but as we shall see there is a lot more to a bird’s world than the information that it receives from its visual system. Other sensory information is constantly in play and interacting to provide each species with a unique suite of information that guides its daily activities. As the book dives deeper into the senses of birds and their diversity across species, we become aware that our world, the human world, is just one way of extracting information from the environment that surrounds us. What we consider to be reality is but one of many worlds in which species live as they rub alongside each other.

      As in all aspects of bird physiology, behaviour, and ecology, diversity is the name of the game. The senses of each bird, and the information that they provide, have been uniquely tuned through natural selection to solve the challenges of different environments, the challenges of different foraging techniques, and the exploitation of different resources. Of course there are commonalities across species, but wherever we look there are differences.

      While we may ponder the intriguing diversity of birds’ bills and describe how they are tools for exploiting different resources in optimal ways, it is easy to overlook that those tools need guidance. In each bird species, the senses have become tuned to provide optimal information that guides behaviour, day in, day out.

      The book first sets out some basic information about each of the main senses. However, from the start, questions are asked about how senses can and do differ between species. This should help the reader to get a grasp of how to compare and investigate different senses in different species, and to form questions about what information different species might have available from moment to moment to guide their behaviour. What is known about each of the main sensory systems of birds is uneven; some species or sensory systems are known about in detail, others less so. Of course, with almost 11,000 species of birds to investigate, it is not surprising that very little is known about many of them. But that is true of all aspects of their ecology, behaviour, and physiology. We have to piece together general truths from patchy information.

      The later chapters bring together what is known across different species, to offer explanations of how birds cope with particular environmental challenges. I have focused particularly on activity at night and activity underwater, both of which provide very different challenges to what we may think of as birds’ normal daytime terrestrial environments. In dwelling on these topics, it is perhaps surprising to discover how often birds are prepared to act guided only by sketchy information, as they operate at the limits of their sensory systems.

      Finally, there is discussion of the many sensory challenges that birds face because of the obstacles that humans have contrived to put in their way, from power lines to windowpanes. A sensory ecology approach does suggest some answers to those challenges, and so the book ends on an optimistic note. It shows how understanding the senses of birds, and the information that they provide, can suggest solutions to the problems that humans have presented them with.

      My aim has been to make technical information understandable and the book readable for the keen birdwatcher and naturalist,