THE COMMON EIDER 000 Eider 1-98.indd 1 07/11/2014 12:25 Process Black THE COMMON EIDER CHRIS WALTHO AND JOHN COULSON T & AD POYSER London 000 Eider 1-98.indd 3 07/11/2014 12:25 Process Black Published 2015 by T & AD Poyser, an imprint of Bloomsbury Publishing Plc, 50 Bedford Square, London WC1B 3DP Copyright © 2015 Chris Waltho and John Coulson Th e moral right of the authors has been asserted No part of this publication may be reproduced or used in any form or by any means – photographic, electronic or mechanical, including photocopying, recording, taping or information storage or retrieval systems – without permission of the publishers. www.bloomsbury.com Bloomsbury is a trademark of Bloomsbury Publishing Plc Bloomsbury Publishing: London, New Delhi, New York and Sydney A CIP catalogue record for this book is available from the British Library ISBN (print) 978-1-4081-2532-8 ISBN (epub) 978-1408-1-5280-5 ISBN (ePDF) 978-1472-9-2092-8 10 9 8 7 6 5 4 3 2 1 Commissioning Editor: Jim Martin Design by Julie Dando at Fluke Art Illustrations by Tim Wootton Contents Acknowledgements 7 Introduction 11 1. Common Eider – some key features 13 2. Origins, taxonomy and diff erentiation 37 3. Distribution, movements and numbers 59 4. Food and feeding 99 5. Predators, parasites and diseases 131 6. Breeding and breeding season 148 7. Egg laying, parasitism, ‘jumbo clutches’ and egg stealing 164 8. Clutch size 181 9. Incubation and hatching success 199 10. Nesting with others: Is the Common Eider really a colonial species? 210 11. Ducklings 219 12. Mortality, survival and non-breeding 233 13. Exploitation, management and conservation 258 14. Th e eiders: comparisons between species 276 Appendix 1: Schematic distribution of the Common Eider and its subspecies 306 Appendix 2: Important conservation sites for the Common Eider 308 Appendix 3: Prey species taken by Common Eiders 313 Appendix 4: Prey dominance in Common Eider diet 317 Appendix 5: Th e number of eggs recorded in samples of Common Eider nests on Inner Farne, Northumberland, 1958 to 2011 325 Appendix 6: Duckling growth 327 Appendix 7: Scientifi c names of species mentioned in the text 331 References 332 Index 347 000 Eider 1-98.indd 5 07/11/2014 12:25 Process Black Chris Waltho wishes to dedicate this book to his wife Anne, and sons Mark and Calum John Coulson wishes to dedicate the book in memory of his mother and father, Ella and Jack Coulson. 000 Eider 1-98.indd 6 07/11/2014 12:25 Process Black Acknowledgements Over many years numerous people from many countries have discussed the biology of eiders with us and we are grateful to all of them for their comments and information. Th ey have often put their ideas to us (often forcefully, at length and invariably disagreeing with others!), and we have listened carefully and appreciated being party to their theories and fi ndings. However, the interpretations of eider biology made in this book are our own and we apologise if we have inadvertently misrepresented the views of others. Th e following gave impetus and early encouragement to this project: Des Th ompson, J.B. Cragg, Colin Galbraith, Stephen Baillie, Richard Hearn, Tim Bowman, Dan Esler, Andy Carroll and Norman Elkins. Nicholas Aebischer gave much assistance in determining the mortality rates of eider females. John Coulson acknowledges the benefi t of the facilities of Durham University and fi nancial support for parts of his long-term studies on colonial seabirds from the Department of Scientifi c and Industrial Research, the Natural Environmental Research Council and the Commissioners for the Royal Exhibition of 1851. Th e following have supported eider monitoring in the Firth of Clyde, and have shared data, analysis and discussion: Bob Furness, Clive Craik and Bernie Zonfrillo. A number of ringing teams have been active within the Firth of Clyde study area, and have collected and shared much data, especially Iain Livingstone, John McKellar, Shona Quinn, Bernie Zonfrillo, Tommy Daniels, Rab Morton, Hayley Douglas and Paul Baker, amongst other members of the Clyde Ringing Group; Bob Furness; Clive Craik and Rob Lightfoot; Dave Grieve and Dave Grant. Th anks are due to RSPB Lochwinnoch, especially Zul Bhatia, his staff and volunteers, for permission to work on Horse Island and for use of data. A very special thanks goes to the following volunteers who have participated in the post-moult census in the Firth of Clyde since 1996: Betty Allison, Chris Armstrong, Tony Baker, John Burton, Tom Callan, Daphne Campbell, Jim Cassels, John Clark, Paul Collin, John Conner, Brian Couper, Rory Cowan, Harry Davidson, Paul Daw, Helen and Aiden Doherty, Jim Duncan, Geoff rey Dunlop, Lindsay Dunlop, Howard Embleton, John and Jean Fitzpatrick, Steve Freear, Dave Freeman, Bob Furness, Roger Garrett, Frances Gatens, Coriina Goeckeritz, Iain Gibson, Alan Gilmour, Eileen Graham, Dave Grant, Jenni Grover, Corrine Hambley, Audrey and Peter Handley, Jackie Hart, John Hawell, Roger Hissett, Leigh Hocking, Alan Hollick, Keith Hoey, Angus Hogg, Frances Hood, Ian Hopkins, Jean Howie, Angela and Chris Irving, David Jardine, Bill and Elinor Kinnaird, Ann Laing, Fiona Laing, Simon Lawrence, Norman Lawrie, Iain Livingstone, Clelland McCallum, Stuart MacFarlane, Jim McGrady, Mary McMillan, Tom McNeish, Eddie Maguire, Susan Mills, Jane Mitchell, Rab Morton, Alex Nicol, Bob and Moira Nuttall, Darren O’Brien, Brian Orr, David and Jean Palmar, Liz Parsons, Alasdair Paterson, Crystal Paterson, Steve Petty, Billy Planck, Scott Riddell, Livingston Russell, Kate Sampson, Geoff Sheppard, John Simpson, Tony Smith, Terry Southall, John Spooner, Peter 7 000 Eider 1-98.indd 7 07/11/2014 12:25 Process Black Th e Common Eider and Margaret Staley, Alan and Susie Stoneham, Jim Tod, Peter Tupman, David Underdown, Dick Vernon, Kevin Waite, Lucy Wallace, Audrey Walters, Ray Welland, Barrie Whattam, Hazel White, Jean Wilkinson, Jim and Val Wilson, Alan Wood, and Ruth Yeats. Th e study during the 1960s on eiders on the Farne Islands, Northumberland, where St Cuthbert many centuries ago proclaimed that the eiders should be protected in perpetuity, were greatly facilitated by accommodation on the upper fl oor of the medieval Pele tower on Inner Farne. Th is was leased for many years from the National Trust by the (now) Natural History Society of Northumbria and used as a study centre. Th is excellent facility permitted the collection of extensive data on eiders by Anne Flowers and particularly by the late Ian Marshall, whose studies extended for three breeding seasons and who sadly died suddenly and before he had completed the full analyses of his fi eld data. Valuable data on eider nests and contents were also collected by Bill Block and John Whittaker. Further studies were made there by a series of students from Durham University. More recent information on eiders nesting on the Farne Islands has been collected by the National Trust wardens under the management of John Walton and supervision of David Steel and they have deposited extensive data as nest records with the British Trust for Ornithology (BTO). Th e BTO through the kindness of David Leech and Carl Barimore made these records available, as well as other eider nest records from other regions of Britain. In 1958, the Duke of Northumberland kindly granted access to Coquet Island to John Coulson and gave his permission for a long-term study of the breeding eiders on the island. Th e study continued annually for 50 years. Th is was the start of the eff ective protection of nesting seabirds on the island, and was achieved with the cooperation of the lighthouse keepers and local boat owners and not least, for six years, by Nigel Langham and Euan Dunn, while they studied the ecology of terns. In 1975, the Royal Society for the Protection of Birds (RSPB) acquired the lease of the island and it was then managed jointly by them, the Natural History Society of Northumbria and the Northumberland Wildlife Trust, and their continued support for the 50-year study is much appreciated. In later years, the RSPB wardens on the island assisted with census work in some years. Details of this study, in addition to those presented here, have been published as scientifi c papers and are listed in the bibliography of this book. Nigel Langham and Euan Dunn, living on the island while PhD students, assisted with records and observations. Richard Wilson and Mary Graham both made studies of eiders and their ducklings along the mainland coast opposite Coquet Island as part of their MSc dissertations and we gratefully acknowledge the information they obtained. John Coulson is most appreciative of the very many people who helped him over the years in searching for eider nests and effi ciently recording details during the census work on Coquet Island, and particularly Julie Porter, Bill Hale, Jennifer Butterfi eld, Nigel Lanham, Euan Dunn, Ian Deans, Sheila Frazer, Nicholas Aebischer and Becky Coulson. Ian Henderson gave considerable technical support in many years of the study. Fortunately, much of the eider study there was made before Health and Safety procedures were introduced for work on the island. Access to islands has played a major role in our eider studies. Boatman Dave Hodge managed journeys to and from Horse Island safely over many years. Th e Shiel family and Pat Laidler of Seahouses often supplied boat travel to and from the Farne Islands. Th e intensive study on Coquet Island was facilitated by boat journeys between Amble and the island made by three generations of the Matthew family, and in more recent years by David Gray and 8 000 Eider 1-98.indd 8 07/11/2014 12:25 Process Black Acknowledgements his son, who conveniently also run Puffi n Cruises around the island.