BTO Research Report No. 224 Winter Ecology of Golden Plovers and Lapwings: A Review and Consideration of Extensive Survey Methods Authors S. Gillings & R.J. Fuller A report by the British Trust for Ornithology July 1999 © British Trust for Ornithology The National Centre for Ornithology, The Nunnery, Thetford, Norfolk IP24 2PU Registered Charity No. 216652 British Trust for Ornithology Winter Ecology of Golden Plovers and Lapwings: A Review and Consideration of Extensive Survey Methods BTO Research Report No. 224 S. Gillings & R.J. Fuller Published in July 1999 by the British Trust for Ornithology The Nunnery, Thetford, Norfolk, IP24 2PU, UK Copyright © British Trust for Ornithology 1999 ISBN 1-902576-18-7 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form, or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of the publishers. CONTENTS Page No. List of Tables ......................................................................................................................3 List of Figures.....................................................................................................................5 List of Appendices..............................................................................................................7 1. EXECUTIVE SUMMARY ...............................................................................................................9 2. INTRODUCTION...........................................................................................................................11 3. LITERATURE REVIEW................................................................................................................13 3.1 Previous Surveys of Wintering Golden Plovers and Lapwings...................................13 3.2 Population Size and Trends............................................................................................13 3.3 Distribution and Movements..........................................................................................15 3.4 Habitat Usage: Regional and Seasonal Differences......................................................16 3.5 Diurnal Behaviour and Moon Phase..............................................................................19 4. EFFECTS OF AGRICULTURAL CHANGE.................................................................................21 5. FUTURE RESEARCH....................................................................................................................23 6. EXISTING DATASETS .................................................................................................................25 6.1 BTO Golden Plover Survey (1976/77 & 1977/78) .........................................................25 6.2 BTO Winter Atlas Data ...................................................................................................25 6.3 ITE Environmental Datasets..........................................................................................25 6.4 Flock Range Register ......................................................................................................26 6.5 BTO/JNCC Wintering Skylark Survey - Additional Species Data .............................26 7. THE KEY AIMS OF AN EXTENSIVE SURVEY.........................................................................27 8. WORK UNDERTAKEN TO DATE TO ASSESS SURVEY METHODS.....................................29 8.1 Intensive Work ................................................................................................................29 8.2 Pilot Surveys ....................................................................................................................30 8.3 Population Estimates Derived from the Wintering Skylark Survey...........................31 9. SURVEY METHODS.....................................................................................................................33 9.1 Grid Squares or Survey Sites .........................................................................................33 9.2 Field Methods ..................................................................................................................34 9.3 Work in Winter 1998/99 .................................................................................................34 Acknowledgements ......................................................................................................................................35 References ....................................................................................................................................................37 Tables............................................................................................................................................................41 Figures ..........................................................................................................................................................45 Appendices ...................................................................................................................................................51 BTO Research Report No. 224 July 1999 1 LIST OF TABLES Page No. Table 3.2.1. Winter populations of Golden Plovers and Lapwings as determined by WeBS and I-WeBS surveys in winter 1995/96.........................................................................................................41 Table 3.2.2. Monthly totals from WeBS sites in Great Britain, Northern Ireland and I-WeBS sites in the Republic of Ireland in winter 1995/96 ......................................................................................................42 Table 3.2.3. Thresholds for designation of sites of international and national importance for Golden Plovers and Lapwings.......................43 Table 8.3.1. Population estimates for wintering Golden Plovers and Lapwings calculated by resampling from the Wintering Skylark Survey’s additional species data ..............................................44 BTO Research Report No. 224 July 1999 2 BTO Research Report No. 224 July 1999 3 LIST OF FIGURES Page No. Figure 3.2.1 Distribution of WeBS and I-WeBS sites of national and international importance of Golden Plovers, based on Cranswick et al. (1997) and Delany (1997) ............................................45 Figure 3.2.2 Distribution of WeBS and I-WeBS sites of national and international importance of Lapwing, based on Cranswick et al. (1997) and Delany (1997)............................................................... 46 Figure 8.1.1 The distribution of fields used by Golden Plovers in winter 1997/98 in our study site in south Norfolk.............................................47 Figure 8.1.2 Bar chart showing the frequency with which fields were used at varying intensity, using the same usage categories as in Figure 8.1.1.48 Figure 9.1.1 A classification of all 10 km squares of the British national grid by farming type ........................................................................................49 Figure 9.1.2 Area of Sugar Beet grown in England and Wales ................................50 BTO Research Report No. 224 July 1999 4 BTO Research Report No. 224 July 1999 5 LIST OF APPENDICES Page No. Appendix 1 Instructions and supporting material provided to volunteers for a pilot survey of wintering Golden Plovers and Lapwings ............51 BTO Research Report No. 224 July 1999 6 BTO Research Report No. 224 July 1999 7 1. EXECUTIVE SUMMARY Britain supports internationally important numbers of Golden Plovers and Lapwings in winter. The majority of these birds spend the winter on lowland farmland where they are missed by existing monitoring schemes. This report is in two main parts: the first is a literature review and the second is a discussion of survey methods. We start by summarising current knowledge of the population size, trends, distribution and movements of plovers wintering in Britain. Patterns of habitat use and how they are affected by season, region and lunar phase are discussed, particularly with respect to plovers on farmland. We discuss components of agricultural change that may have affected plovers and highlight the need for further research, particularly extensive surveys. We describe several sources of data on plover numbers and distribution from previous surveys that are available to researchers planning extensive and intensive surveys. We then describe work undertaken by ourselves and BTO volunteers during winters 1996/97 and 1997/98 using different counting techniques to identify suitable methods for an extensive volunteer based survey of wintering plovers. Problems identified include the highly clumped distribution of plover flocks, the high frequency of movements of entire flocks at a local level, and the changing composition of flocks in terms of individuals. The main implication of this work is that surveys of randomly selected grid squares are unlikely to produce meaningful population estimates for Golden Plovers and Lapwings. Suggestions of alternative methods for surveying plovers are made. BTO Research Report No. 224 July 1999 8 BTO Research Report No. 224 July 1999 9 2. INTRODUCTION Long-term monitoring of British breeding birds by the British Trust for Ornithology (BTO) has revealed dramatic declines in populations of many species of bird associated with lowland farmland (Fuller et al. 1995). Over the last 25 years a number of species have decreased