Republic of Ireland Hen Harrier Survey 2010
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Republic of Ireland Hen Harrier Survey 2010 Irish Wildlife Manuals No. 59 Republic of Ireland National Hen Harrier Survey 2010 Ruddock, M.,1 Dunlop, B.J.,1 O’Toole, L.,1, 2 Mee, A.,1, 2 & Nagle, T.2 In collaboration with Lyden, J.,2 Clarke, D.J.,2 O’Donoghue, B.G.,3 Wilson, M.W.,4 Oliver, G.A.,3, 4 McGeough, C.,2 Lusby, J.,5 Monaghan, J.,3 Porter, B.,5 O’Mahony, B.,4 Troake, P.,4 Norriss, D.,3 & Tierney, D.3 1 Golden Eagle Trust Ltd, 22 Fitzwilliam Square, Dublin 2 www.goldeneagle.ie 2 Irish Raptor Study Group c/o Direen, Black Valley, Kerry 3 National Parks & Wildlife Service, Department of Environment, Heritage & Local Government, 7 Ely Place, Dublin 2 www.npws.ie 4 Department of Zoology, Ecology & Plant Science, University College Cork, Distillery Fields, North Mall, Co. Cork www.ucc.ie 5 Birdwatch Ireland, Midlands Office, Crank House, Banagher, Co. Offaly www.birdwatchireland.ie 6 Contact Nature, 4 Kent Terrace, Barnhill, Dalkey, Co. Dublin Citation: Ruddock, M. & Dunlop, B.J., O’Toole, L., Mee, A., Nagle, T. (2012) Republic of Ireland National Hen Harrier Survey 2010. Irish Wildlife Manual, No. 59. National Parks and Wildlife Service, Department of Arts, Heritage and the Gaeltacht, Dublin, Ireland. Keywords: hen harrier, circus cyaneus, national survey, population estimate, habitat change, forestry, windfarms, disturbance, upland, heather moorland, burning, Special Protection Area (SPA), demography. Site list: 004160; 004161; 004162; 004165; 004167; 004168 Cover photos: Adult female hen harrier © M. Ruddock The NPWS Project Officer for this report was: David Norriss Irish Wildlife Manuals Series Editors: N. Kingston & F. Marnell © National Parks and Wildlife Service 2012 ISSN 1393 – 6670 Republic of Ireland Hen Harrier Survey 2010 __________________________________ Contents Executive Summary ............................................................................................................................................. 3 Collaboration ......................................................................................................................................................... 4 Acknowledgements .............................................................................................................................................. 5 1.0 Introduction ..................................................................................................................................................... 6 2.0 Methods ........................................................................................................................................................... 9 2.1 Survey design and implementation ......................................................................................................... 9 2.2 Field survey methods and recording ..................................................................................................... 10 2.3 Other research ........................................................................................................................................... 13 2.4 Calculation of population estimates, population change and breeding density ............................. 14 2.5 Assessment of population estimates and population changes within SPAs .................................... 15 2.6 Calculation of breeding outcomes and nest habitat ............................................................................. 16 2.7 Calculation of plantation forest habitat changes between surveys ................................................... 16 3.0 Results ............................................................................................................................................................ 17 3.1. Survey implementation, coverage and data submission ................................................................... 17 3.2 Survey effort and observations ............................................................................................................... 20 3.3 Other research ........................................................................................................................................... 24 3.4 Calculation of population estimates, population change and breeding density ............................. 25 3.5 Assessment of population estimates and population changes within SPAs .................................... 38 3.6 Calculation of breeding outcomes and nest habitat ............................................................................. 41 3.7 Calculation of forest habitat changes between surveys ...................................................................... 49 4.0 Discussion ...................................................................................................................................................... 53 4.1. Survey implementation, coverage and data submission ................................................................... 53 4.2 Survey effort and observations ............................................................................................................... 54 1 Republic of Ireland Hen Harrier Survey 2010 __________________________________ 4.3 Other research ........................................................................................................................................... 54 4.4 Analysis of population estimates, population change and breeding density .................................. 55 4.5 Analysis of population estimates and population changes within SPAs .......................................... 57 4.6 Analysis of breeding outcomes and nest habitat .................................................................................. 58 5.0 Conclusions & Recommendations .............................................................................................................. 62 6.0 Bibliography & Relevant Literature ........................................................................................................... 64 7.0 Appendices .................................................................................................................................................... 73 Appendix A. 10km square map showing topography, geo‐referenced grid and habitats. .................. 73 Appendix B. 10km square aerial photograph showing distribution of habitat types ........................... 74 Appendix C. Moulted feather collection sheet and instructions .............................................................. 75 Appendix D. Prey remains collection sheet and instructions ................................................................... 77 Appendix E. Map showing distribution of 10km squares containing merlin records. ......................... 79 Appendix F. Map showing distribution of 10km squares containing buzzard records ....................... 80 Appendix G. Map showing distribution of 10km squares containing kestrel records ......................... 81 Appendix H. Map showing distribution of 10km squares containing peregrine records. ................... 82 Appendix I. Map showing distribution of 10km squares containing sparrowhawk records .............. 83 Appendix J. Map showing distribution of 10km squares containing goshawk records ....................... 84 Appendix K. Map showing distribution of 10km squares containing red kite records ........................ 85 Appendix L. Map showing distribution of 10km squares containing long‐eared owl records ........... 86 Appendix M. Map showing distribution of 10km squares containing barn owl records ..................... 87 Appendix N. Photographs showing juvenile chewed hen harrier feathers. .......................................... 88 Appendix O. Population projection model ................................................................................................. 89 2 Republic of Ireland Hen Harrier Survey 2010 ___________________________________ Executive Summary The hen harrier (Circus cyaneus) is a species of high conservation concern. It is listed on Annex I of the EU Birds Directive which provides a legislative framework for assessing and ensuring the conservation of the hen harrier. This framework includes monitoring, research and the designation of Special Protection Areas (SPAs). A national survey of hen harriers was carried out during 2010 with the aims of quantifying the size of the breeding population and examining changes in the national, regional and SPA populations since the previous national survey in 2005. Survey effort and results were organised according to a grid of 10km squares which were stratified according to suitability of habitat and historical hen harrier occupancy. Over 4000 hours of fieldwork were carried out in these squares by a team of volunteers and full‐time fieldworkers to establish the breeding status and occurrence of hen harriers in all suitable breeding habitats. An estimated 128 to 172 breeding pairs were recorded within 69 10km squares. The national population appears to be stable since the last national survey although the accuracy of estimates of change are complicated due to more than double the survey effort during 2010 from the 2005 survey. Regardless, there were severe regional declines noted in the Slieve Aughties and in the Stack’s, Glanarudderies, Knockanefune, Mullaghareirks, North of Abbeyfeale complex. Numbers of hen harriers in other areas were observed to have increased, largely a reflection of additional field effort. The hen harrier populations within the six SPAs have declined overall