The Whooper Swan 9781472596819, 9780713665703, 9781408133361

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THE WHOOPER SWAN

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For Dennis and Mavis

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THE WHOOPER SWAN

MARK BRAZIL Illustrated with line drawings and colour plates by DAFILA SCOTT

T & A D POYSER London

Published 2003 by T & A D Poyser, an imprint of A&C Black Publishers Ltd, 36 Soho Square, London W1D 3QY Electronic edition published 2010 www.acblack.com Copyright © 2003 text by Mark Brazil Copyright © 2003 illustrations by Dafila Scott ISBN: 978-0-7136-6570-3 e-PDF ISBN 978-1-4081-3336-1 A CIP catalogue record for this book is available from the British Library. All rights reserved. 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. Typeset by J&L Composition, Filey, North Yorkshire 10 9 8 7 6 5 4 3 2 1

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The Wild Swans At Coole The trees are in their autumn beauty, The woodland paths are dry, Under the October twilight the water Mirrors a still sky; Upon the brimming water among the stones Are nine-and-fifty Swans. The nineteenth autumn has come upon me Since I first made my count; I saw, before I had well finished, All suddenly mount And scatter wheeling in great broken rings Upon their clamorous wings. I have looked upon those brilliant creatures, And now my heart is sore. All’s changed since I, hearing at twilight, The first time on this shore, The bell-beat of their wings above my head, Trod with a lighter tread. Unwearied still, lover by lover, They paddle in the cold Companionable streams or climb the air; Their hearts have not grown old; Passion or conquest, wander where they will, Attend upon them still. But now they drift on the still water, Mysterious, beautiful; Among what rushes will they build, By what lake’s edge or pool Delight men’s eyes when I awake some day To find they have flown away? W. B. Yeats (1865–1939)

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Contents List of Figures List of Tables Preface Acknowledgements

13 19 21 23

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A SWAN’S WORLD Introduction Swan classification Whooper Swan Cygnus cygnus (Linnaeus, 1758) Trumpeter Swan Cygnus buccinator Richardson, 1832 Tundra Swan Cygnus columbianus (Ord, 1815) Whistling Swan Cygnus columbianus columbianus Bewick’s Swan Cygnus columbianus bewickii (Yarrell 1830) Mute Swan Cygnus olor (Gmelin, 1789) Black Swan Cygnus atratus (Latham, 1790) Black-necked Swan Cygnus melanocoryphus (Molina, 1782) Coscoroba Swan Coscoroba coscoroba (Molina, 1782) Extinct swan relatives

26 26 30 32 37 40 40 43 45 47 49 50 51

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SWAN CULTURE Naming and knowing Bird of myth, legend and symbolism

53 53 61

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THE WHOOPER SWAN, A CLOSER LOOK Distribution Description Plumage and posture Soft parts Geographical variation Habitat and habits Social behaviour Hybridisation

74 74 75 75 83 85 89 97 100

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RANGE, HABITAT AND POPULATION— EUROPE Introduction Range Habitat Breeding season habitat preferences Winter habitat use

103 103 104 105 105 106

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Contents Population Iceland Icelandic population overview The Icelandic breeding population Whooper Swans wintering in Iceland The United Kingdom The United Kingdom’s breeding population The United Kingdom’s wintering population The size of the wintering population in the UK and Ireland The proportion of cygnets in the wintering population The significance of certain sites and their pattern of use The pattern of use at Wildfowl and Wetland Trust Centres Ireland Wales Fennoscandian/Northwest Russian breeding population overview Fennoscandia and continental Europe Norway Sweden Finland Wintering in continental Europe Denmark Germany Netherlands Belgium France Wintering in Mediterranean Europe Greece The eastern Baltic region Estonia Latvia Lithuania Poland Czech Republic Hungary, Romania, Bulgaria Belarus Ukraine Turkey

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RANGE, HABITAT AND POPULATION—RUSSIA AND ASIA, AND VAGRANCY Introduction Russia and Associated States and Republics Western Russia: from Europe to the Urals West Siberia: from the Urals to the Yenisei Trans-Uralia

108 108 108 109 113 114 114 120 125 129 132 133 140 148 148 149 150 151 155 157 159 160 161 161 162 162 162 163 164 165 166 167 170 170 171 171 172 173 173 175 175 183 184

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9 The West Siberian Plain Altai Krai Tuva and Khakassia Central and eastern Siberia: from the Yenisei to the Lena The Baikal Region The Russian Far East: from the Lena to the Bering Sea

Asia Armenia Azerbaijan Kazakhstan Turkmenistan Uzbekistan Kyrgyzstan Mongolia China The Korean Peninsula North Korea South Korea Japan Vagrancy Old World vagrancy Slovenia The Mediterranean region Asia New World vagrancy Vagrancy in western North America (Canada and USA) Alaska British Columbia Alberta Ontario Oregon California Montana North Dakota Vagrancy in eastern North America (Canada and USA) Québec Maine, Massachusetts, New York, New Brunswick Ohio 6

FOOD, FEEDING, AND FLOCKING BEHAVIOUR The Whooper Swan’s diet Methods of feeding Dabbling Dipping

188 193 194 195 197 198 210 210 210 211 213 213 214 215 216 219 219 220 221 223 224 224 224 226 226 227 228 228 229 229 229 229 230 230 230 230 231 231 232 232 241 241 241

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Contents Upending Digging Grazing Picking Shovelling Pecking The historical development of field feeding and its influence on behaviour The implications of field feeding Feeding associations Flocking and the composition of flocks Associations with other species Winter feeding and habitat selection Habitat selection Feeding behaviour Feeding behaviour in tidal areas Feeding routines in terrestrial and aquatic habitats Daily movements: arrival and departure times The effect of temperature Time budgets in terrestrial and aquatic habitats An overview of feeding routines Feeding and vigilance in winter Dropping rate Food intake Vigilance behaviour The relationship between flock size and behaviour SOCIAL BEHAVIOUR Social behaviour in winter Displays in winter Pre-flight signalling Aggressive behaviour Water boiling Aggression and coprophagy Greeting or Triumph Ceremony Territory and Territorial Behaviour in Summer Displays used in territorial and nest defence Territorial display between males Threat displays at the nest Voice

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BREEDING BIOLOGY AND BEHAVIOUR Introduction Habitat selection

243 244 244 245 245 245 246 250 253 253 258 259 260 261 263 264 265 267 267 273 277 279 280 281 282 286 286 288 288 293 295 296 297 298 300 301 303 303 306 306 309

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Contents The nest Nest site selection Nest construction Pair bonding Copulation Eggs Clutch size Incubation Female behaviour during the incubation period Incubation breaks Male behaviour during the incubation period The relationship between male and female behaviour during the incubation period Distance from the nest during the incubation period Brood size Cygnet growth Family life Family life from hatching to fledging The proximity of parents and cygnets Parental vigilance and feeding during the fledging period Space utilisation at Arnarvatn Factors affecting breeding success

11 311 311 313 315 316 319 321 326 328 329 330 331 332 334 340 343 344 346 348 349 352

NON-BREEDING WHOOPER SWANS Introduction Fluctuation in numbers at an Icelandic moulting area Status of summering Whooper Swans The activity patterns of non-breeders Space utilisation by moulting Whooper Swans in Iceland Moult

356 356 360 366 368 370 371

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MOVEMENTS AND MIGRATION Introduction Patterns of migration Movements and migration of Icelandic/Irish/British Whooper Swans Movements and migration of continental European Whooper Swans Movements and migration of eastern Whooper Swans Marking methods

380 380 391 394 407 413 425

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IN SICKNESS AND IN HEALTH Introduction Longevity and mortality Flying accidents Poisoning

429 429 433 437 439

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Contents Hunting Disturbance Predation Illness Legal protection and conservation

443 447 448 450 453

Appendices 1 Scientific names of bird and mammal species appearing in the text 2 Swan biometrics 3 Foods eaten by Whooper Swans

456 459 461

Notes

464

Bibliography

468

Index

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List of Figures CHAPTER 1 Figure 1.1. Figure 1.2. Figure 1.3. Figure 1.4.

Amidst morning mist beside a hotspring. As long as there is access to food and open water Whooper Swans can survive severe northern winters. Kussharo-ko, a regular winter haunt in northern Japan. Current breeding range of the Trumpeter Swan shown as shaded areas (after Hawkings et al. 2002).

28 35 37 40

CHAPTER 2 Figure 2.1. Figure 2.2.

Ice, snow and dawn mist are vital ingredients when photographing The ‘Angels of Winter.’ Cultural transmission in stone, begun in the Stone Age continues today: Odaito, Japan.

71 73

CHAPTER 3 Figure 3.1. Figure 3.2. Figure 3.3. Figure 3.4. Figure 3.5. Figure 3.6. Figure 3.7. Figure 3.8. Figure 3.9. Figure 3.10. Figure 3.11. Figure 3.12.

Poise and grace are among the attributes of the pure white Whooper Swan. First winter birds are ash grey with a white-based bill. The profile and imperious demeanour of the Whooper Swan are distinctive. Grace in flight is achieved only after a labouring run. Whooper Swans commonly circle their chosen landing site descending slowly. Orange or rusty staining of the head and neck is a common feature on the breeding grounds. The black-based bill pattern is common in the west, but scarce in the east. Variation in bill pattern among yellownebs in Whooper Swans (above) and Bewick’s Swans (below). Classification of Whooper Swan bill patterns. Black-based yellownebs are most common in UK and Iceland, Yellow-based yellownebs are most common in Japan. Winter woodlands; A rare and only temporary habitat choice for these Whoopers in Hokkaido. Preening, essential maintenance behaviour.

76 77 78 79 79 81 83 86 87 89 90 93

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List of Figures Scratch-preening. Combined wing- and leg-stretch. Whooper Swans will roost far out on frozen lakes. The waters of this coastal bay have frozen around these roosting birds during the night. A dedicated swan-keeper in Hokkaido. Mute Swan/Whooper Swan hybrid (after Owens (1995)).

94 95 96 96 99 101

CHAPTER 4 Figure 4.1. Figure 4.2.

Figure 4.3. Figure 4.4. Figure 4.5. Figure 4.6. Figure 4.7. Figure 4.8.

Geothermal activity makes wintering at some northern sites possible. The distribution of main staging sites of Whooper Swans in Iceland in October 1982. Small circles indicate 11–100, large circles 101–1,000 and squares over 1,000 birds (after Gardarsson & Skarphedinsson 1984). Distribution of Whooper Swans wintering in Iceland, January 2000 (after Cranswick et al. 2002). A European winter refuge. Distribution of Whooper Swans in Britain and Ireland in January 2000 (after Cranswick 2002). The locations of three internationally significant winter flocks in the UK. Peak Whooper Swan numbers at WWT Caerlaverock, Martin Mere and Welney, 1990–2001. Whooper Swans staging in Estonia in April.

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111 114 121 129 134 136 164

CHAPTER 5 Figure 5.1. Figure 5.2. Figure 5.3. Figure 5.4. Figure 5.5. Figure 5.6. Figure 5.7.

The approximate breeding and wintering ranges of the Whooper Swan in Russia and adjacent countries (Brazil & Shergalin 2002). Western Russia showing the main locations mentioned and the approximate breeding and wintering areas of the Whooper Swan (Brazil & Shergalin 2002). Western Siberia showing main locations mentioned and the approximate breeding range of the Whooper Swan (Brazil & Shergalin 2002). Small flock of Whoopers arriving at a taiga forest lake during migration. Central and Eastern Siberia showing main locations mentioned and approximate breeding range of Whooper Swan (after Brazil & Shergalin in press). The Russian Far East showing the main locations mentioned and the approximate breeding and wintering areas of the Whooper Swan. Global warming may be encouraging Whoopers to expand their range northwards in northeastern Russia.

174 176 185 190 196 199 203

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List of Figures Figure 5.8. Figure 5.9. Figure 5.10. Figure 5.11. Figure 5.12.

15 Polynias are vital for wintering birds and early migrants. In east Asia, Whooper Swans frequent volcanic landscapes. Odaito. A regular coastal wintering site in east Hokkaido. Numbers of Whooper Swans wintering in Japan 1982–1999. Records of Whooper Swans outside their normal breeding and wintering ranges (those in eastern North America probably refer to escaped or released birds).

205 209 221 223 225

CHAPTER 6 Figure 6.1. Figure 6.2. Figure 6.3. Figure 6.4. Figure 6.5. Figure 6.6. Figure 6.7. Figure 6.8. Figure 6.9. Figure 6.10. Figure 6.11. Figure 6.12. Figure 6.13.

Dwarf bamboo emerging from beneath snow is a rare food for Whooper Swans. Whooper Swans foraging on abundant eelgrass, Hokkaido. The posture while drinking closely resembles ‘dabbling’. Dipping for eelgrass. A young Whooper upending. Whooper Swans on stubble field in central Scotland. Whoopers are very sociable in winter. The percentage of cygnets in relation to flock size; 1977–80 (after Brazil 1981c). Map of the study areas east and west of Stirling, Scotland (after Brazil 1981c). Lakes are important winter habitat. Providing food at wintering sites affects behaviour, allowing more time for social interactions, vigilance behaviour and loafing. The influence of flock size on the number of birds feeding. (n87), r0.984, p