Estuary Birds of Britain and Ireland

457 Pages·2010·20.12 MB·English

by  A. J. Prater

ESTUARY BIRDS OF BRITAIN AND IRELAND
This page intentionally left blank
ESTUARY BIRDS
of Britain and Ireland
by A.]. PRATER
Illustrated by JOHN BUSBY
T & A D POYSER
Calton
First published 1981 by T & AD Poyser Ltd
Print-on-demand and digital editions published 2010 by T & AD Poyser,
an imprint of A&C Black Publishers Ltd, 36 Soho Square, London W1D 3QY
Copyright © 1981 British Trust for Ornithology
A Report of the Birds of Estuaries Enquiry conducted under contract from the Nature
Conservancy Council by the British Trust for Ornithology with the help of the Royal
Society for the Protection of Birds and the Wildfowl Trust
ISBN (print) 978-1-4081-3849-6
ISBN (epub) 978-1-4081-3847-2
ISBN (e-pdf) 978-1-4081-3848-9
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.
Visit www.acblack.com/naturalhistory to find out more about our
authors and their books. You will find extracts, author interviews and
our blog, and you can sign up for newsletters to be the first to hear
about our latest releases and special offers.
Contents
Introduction 11
Acknowledgements 15
1 THE NATURE OF AN ESTUARY 17
Principal characteristics 17
Estuarine plants 20
Estuarine animals 22
Distribution of estuarine invertebrates 26
Estuarine food chains 31
2 PATTERNS OF SHOREBIRD FEEDING 34
What to eat 34
Where to feed 38
When to feed 45
Feeding success 46
Shorebirds in midwinter 49
Summary 50
3 MIGRATIONS AND DISTRIBUTIONS IN WESTERN EUROPE 51
Migratory patterns 51
International counts 59
Distribution in Britain and Ireland 62
4 THREATS - BARRAGES AND RESERVOIRS 71
Freshwater reservoir proposals 71
Tidal power proposals 82
Overall implications 86
Specific implications 92
5 OTHER THREATS TO ESTUARY BIRDS 98
Reclamations 98
Pollution 106
Leisure activities 109
Shellfish fisheries 112
Natural problems 114
The future 115
6 THE COUNTS 118
Organisation and methods 118
Accuracy 123
Criteria of importance 126
7 THE ESTUARIES - AN INTRODUCTION 131
8 EASTERN ENGLAND 133
9 SOUTHERN ENGLAND 163
10 SOUTH-WESTERN ENGLAND 178
11 WALES 191
12 NORTH-WESTERN ENGLAND 205
5
6 Contents
13 SCOTLAND 222
14 NORTHERN IRELAND 250
15 REPUBLIC OF IRELAND 257
16 THE ESTUARINE BIRDS - AN INTRODUCTION 265
17 THE SPECIES ACCOUNTS (in Voous order) 267
Appendices
1 Highest average monthly counts of main species for each estuary 401
2 Criteria of international importance for species 418
3 Criteria of national (British) importance for species 422
References 426
Index 435
List of Plates
(between pages 192 and 193)
1 The Wash at low tide; Oystercatchers, Bull Island, Dublin
2 Pagham Harbour, West Sussex, from the air
3 Dunlin coming in to roost; Oystercatchers in the Netherlands
4 Knot on the Dee estuary; a subroost forming, Morecambe Bay
5 Eroding saltmarsh, the Solway Firth; the Medway estuary in winter
6 The foreshore at Caerlaverock
7 The Medway saltmarshes
8 Migrants on the Dee estuary; Pink-footed Geese, the Ribble estuary
9 Dark-bellied Brent Geese on the Swale estuary; Redshanks
10 Upper reaches of the Adur, West Sussex, from the air
11 The Medway saltmarsh and oil spillage; a Salicornia saltmarsh on the Ribble
estuary
12 Windmill Creek, Isle of Sheppey
13 The Thames at Cross Ness; Mute Swans at a grain wharf
14 Whimbrel; Red-throated Diver
15 Shelduck on the North Kent marshes; Sandwich Terns, Norfolk
16 Lapwing; Little Terns courtship feeding
List of Figures
List of estuaries counted (with map) 13
1:1 Relationship of organic nitrogen and invertebrate biomass 18
1:2 Salinity pattern in an estuary 19
1:3 Plant zonation on an estuary 21
1:4 Size of cockles and mussels in different salinities 23
1:5 Number of invertebrate species along an estuary 24
1:6 Main invertebrates taken by shorebirds 24
1:7 Invertebrate burrowing depths and bill sizes of waders 26
1:8 Tidal levels where Macoma, Hydrobia and Corophium occur 28
1:9 Sizes of cockles in the mud and predated by Oystercatchers 29
1:10 Simple food chain 31
1:11 Simple estuarine food web 32
1:12 Detailed estuarine food web 33
2:1 Redshank ingestion rate of Nereis and Nephthys 35
2:2 Size of Corophium taken by Redshanks 36
2:3 Wader body size and size of prey taken 37
2:4 Proportion of Corophium and Nereis taken by Redshanks 38
2:5 Feeding rate of Redshanks and distance from shore 39
2:6 Correlation of density of Curlew and its main prey 40
2:7 Distribution of feeding Knot, Dunlin and Redshank on the Firth of
Forth 41
2:8 Variations in cockle capture rate of Oystercatchers 42
2:9 Variation of Food supply during the year 42
2: 1 0 Rates of cockle predation by Oystercatchers in different areas 43
2: 11 Responses of Corophium to disturbance 44
2: 12 Effect of closeness of Redshanks on Corophium numbers taken 44
2: 13 Activity cycle of Knot 45
2: 14 Effect of temperature on availability of Arenicola 47
3: 1 Breeding grounds of estuary birds of Britain 52
3:2 Ice Age refuges and migration routes of estuary birds 53
3:3 Broad distribution of ducks in west Europe 56
3:4 Most important areas for waders in west Europe 57
3:5 British and Irish estuaries of international importance 62
3:6 British estuaries of national importance 63
3:7 Wader densities and estuary size 67
3:8 Number of waders and estuary size 68
4: 1 Cross section of bunded reservoir 72
4:2-7 Variations in barrage designs on the Dee 74-5
4:8-11 Variation in reservoir designs on Morecambe Bay 76-7
4: 12 Initial design of Wash barrage/reservoir 79
4:13-16 Variations in reservoir designs on the Wash 80-1
4:17-22 Variations in barrage designs on the Severn 82-5
5: 1 Major threats to British and Irish estuaries 100
5:2 Reclamation of Teesmouth 101
7
8 List of Figures
5:3 Changes in numbers of waders at Teesmouth 102
5:4 Reclamation and pollution of Langstone Harbour 105
5:5 Yachting clubs on English and Welsh estuaries 110
5:6 Cockle landings and Oystercatchers killed on Morecambe Bay and the
Burry Inlet 113
6:1 Estuary birds counting card 120
8:1 Wader distribution in north-east England 140
8:2 Bird distribution on the Humber 142
8:3 Bird distribution on the Wash and north Norfolk 145
8:4 Bird distribution in south Suffolk and north Essex 151
8:5 Bird distribution around the Thames 156
9:1 Bird distribution in west Sussex and east Hampshire 168
9:2 Bird distribution around Southampton and the Solent 171
10:1 Bird distribution on the Severn 189
11:1 Bird distribution in Swansea and Carmarthen Bays 197
12:1 Bird distribution between the Dee and the Ribble 215
12:2 Bird distribution in Morecambe Bay and the Duddon 217
12:3 Bird distribution in the Solway Firth 219
13:1 Bird distribution in the Moray Firth Basin 237
13:2 Bird distribution in the Firth of Forth 248
Note: Figures for Chapter 17, The Species Accounts, are by species
arranged in Voous order.
List of Tables
1: 1 Main invertebrates in British estuaries 25
1:2 Densities of main invertebrates taken by birds 27
1:3 Distribution of invertebrate groups 27
2:1 Invertebrates taken by shorebirds 36
2:2 Habitat tolerances of waders 39
2:3 Risk of waders dying in winter and autumn/spring 40
2:4 Feeding efficiency in adult and juvenile Turnstones 47
3:1 Numbers of swans, ducks and waters in Europe 60
3:2 Numbers of geese in Europe 61
3:3 Regional density of waders in Britain 67
4: 1 Population forecasts 72
5:1 Membership of various leisure organisations 109
6:1 Dates of coordinated counts 119
6:2 Temperatures during the estuaries counts 124
6:3 Contribution of known wader roosts, major and small; towards
accuracy of counts 125
6:4 Percentage of some species occurring on estuaries 127
8:1 Principal bird species - eastern England 135
8:2 Internationally important estuaries - eastern England 136
List of Tables 9
8:3 Nationally important species at Lindisfarne 138
8:4a Numbers of waders on the Northumberland coast 139
8:4b Important species on the Northumberland coast 139
8:5 Nationally important species at Teesmouth 141
8:6 Nationally important species on the Humber 143
8:7 Peak counts of Pink-footed Geese on the Humber 143
8:8 Nationally important species on the Wash 144
8: 9 Nationally important species breeding on the Wash 146
8:10 Numbers of important species in north Norfolk 147
8: 11 Nationally important species on the Orwell 150
8:12 Nationally important species on the Stour 150
8:13 Nationally important species on Hamford Water 152
8:14 Nationally important species on the Colne 153
8: 15 Nationally important species on the Blackwater 154
8:16 Nationally important species on Dengie Flats 155
8:17 Nationally important species on the Crouch 155
8:18 Nationally important species on Foulness 157
8: 19 Nationally important species at Leigh/Canvey 157
8:20 Nationally important species on the Inner Thames 158
8:21 Nationally important species on the north Kent Marshes 159
8:22 Nationally important species on the Medway 160
8:23 Nationally important species on the Swale 161
9: 1 Principal species in southern England 165
9:2 Internationally important estuaries in southern England 166
9:3 Nationally important species in Pagham Harbour 167
9:4 Nationally important species in Chichester Harbour 168
9:5 Nationally important species in Langstone Harbour 169
9: 6 Changes in numbers of birds in Langstone Harbour 170
9:7 Nationally important species in Portsmouth Harbour 170
9:8 Nationally important species in Southampton Water 172
9:9 Nationally important species in the north-west Solent 173
9: 10 Nationally important species in Poole Harbour 175
9: 11 Nationally important species in the Fleet 177
10:1 Principal species in south-western England 180
10:2 Internationally important estuaries in south-western England 181
10:3 Nationally important species on the Exe 182
10:4 Nationally important species on the Tamar 184
10:5 Nationally important species on the Fal 185
10:6 Nationally important species on the Camel 186
10:7 Nationally important species on the TawlTorridge 187
10:8 Nationally important species on the Severn 188
11:1 Principal species in Wales 193
11:2 Internationally important estuaries in Wales 194
11:3 Nationally important species on the Welsh Severn 195
11:4 Nationally important species on Swansea Bay 196
11:5 Nationally important species on the Burry Inlet 197
11:6 Nationally important species on the Three Rivers 198
11: 7 Nationally important species on the Dyfi 200
11:8 Nationally important species on Conwy Bay 203