BTO Research Report No. 590 Measuring the interaction between marine features of Special Protection Areas with offshore wind farm development zones through telemetry: first breeding season report Authors Chris B. Thaxter1, Viola H. Ross-Smith1, Nigel A. Clark1, Greg J. Conway1, Mark. M. Rehfisch1, Willem Bouten2 and Niall H.K. Burton1 Report of work carried out by the British Trust for Ornithology1 in association with the University of Amsterdam2 on behalf of the Department of Energy and Climate Change May 2011 This document was produced as part of the UK Department of Energy and Climate Change's offshore energy Strategic Environmental Assessment programme. Crown Copyright, all rights reserved URN 11D/846 British Trust for Ornithology The British Trust for Ornithology, The Nunnery, Thetford, Norfolk IP24 2PU Registered Charity No. 216652 CONTENTS Page No. List of Tables ................................................................................................................................. 3 List of Figures ................................................................................................................................. 5 List of Appendices ............................................................................................................................. 7 EXECUTIVE SUMMARY ...................................................................................................................... 9 1. INTRODUCTION .................................................................................................................. 11 1.1 Background ........................................................................................................................ 11 1.2 Project aims ....................................................................................................................... 11 1.3 Tagging birds to understand interactions ........................................................................... 12 1.3.1 Breeding season movements ................................................................................. 12 1.3.2 Non-breeding season movements ......................................................................... 12 1.3.3 Flight altitudes of birds .......................................................................................... 13 1.4 Focal species ...................................................................................................................... 13 1.4.1 Lesser Black-backed Gulls ...................................................................................... 14 1.4.2 Great Skuas ............................................................................................................ 14 2. METHODS ........................................................................................................................... 16 2.1 Field sites ........................................................................................................................... 16 2.2 The GPS system .................................................................................................................. 16 2.3 Capturing and attaching devices ........................................................................................ 16 2.4 Monitoring the potential effects of devices ....................................................................... 19 2.4.1 Lesser Black-backed Gulls ...................................................................................... 19 2.4.2 Great Skuas ............................................................................................................ 20 2.5 Data collection protocols, post-processing and analyses ................................................... 22 2.5.1 Connectivity with proposed and consented wind farms ........................................ 23 2.5.2 Overlap with proposed and consented wind farms ............................................... 23 2.5.2.1 Spatial overlap........................................................................................................ 23 2.5.2.2 Time budgets of birds ............................................................................................. 24 2.5.3 Flight altitudes ....................................................................................................... 24 2.5.4 Formal statistical tests ........................................................................................... 25 3. RESULTS ............................................................................................................................. 27 3.1 Descriptive trip statistics .................................................................................................... 27 3.1.1 Lesser Black-backed Gull ........................................................................................ 27 3.1.2 Great Skua ............................................................................................................. 30 3.2 Connectivity with proposed and consented wind farms .................................................... 31 3.2.1 Lesser Black-backed Gull ........................................................................................ 31 3.2.2 Great Skua ............................................................................................................. 31 May 2011 1 Page No. 3.3 Overlap with proposed and consented wind farms ............................................................ 31 3.3.1 Spatial overlap ....................................................................................................... 31 3.3.1.1 Lesser Black-backed Gull ........................................................................................ 31 3.3.1.2 Great Skua .............................................................................................................. 36 3.3.2 Time budget analyses ............................................................................................ 38 3.3.2.1 Lesser Black-backed Gull ........................................................................................ 38 3.3.2.2 Great Skua .............................................................................................................. 39 3.4 Altitude .............................................................................................................................. 39 3.4.1 Test tag at Orford Ness .......................................................................................... 39 3.4.2 Species altitude data: Lesser Black-backed Gull ..................................................... 41 3.4.2.1 Accuracy ................................................................................................................. 42 3.4.2.2 Precision ................................................................................................................ 45 3.4.3 Species altitude data: Great Skua .......................................................................... 47 3.4.3.1 Accuracy ................................................................................................................. 47 3.4.3.2 Precision ................................................................................................................ 48 4. DISCUSSION ........................................................................................................................ 51 4.1 Caveats in the current data ................................................................................................ 51 4.2 Connectivity with proposed and consented wind farms .................................................... 51 4.3 Overlap with proposed and consented wind farms ............................................................ 52 4.3.1 Spatial overlap ....................................................................................................... 52 4.3.2 Temporal overlap .................................................................................................. 52 4.4 Assessment of the flight altitudes ...................................................................................... 52 4.4.1 Accuracy ................................................................................................................ 52 4.4.2 Precision ................................................................................................................ 53 4.4.3 Flight altitudes ....................................................................................................... 53 4.5 Future study: winter 2010/11 and the 2011 breeding season ............................................ 54 4.6 Concluding comments ........................................................................................................ 55 Acknowledgements ........................................................................................................................ 56 References ............................................................................................................................... 58 Appendices ............................................................................................................................... 63 May 2011 2 LIST OF TABLES Page No. Table 1 Development periods for tags on (a) Lesser Black-backed Gulls and (b) Great Skuas ...................................................................................................................... 18 Table 2 Fate of all (a) Lesser Black-backed Gull and (b) Great Skua nests in this study (one