Seabird Numbers and Breeding Success in Britain and Ireland, 2005

UK Nature Conservation No. 30 Seabird numbers and breeding success in Britain and Ireland, 2005 R.A. Mavor, M. Parsons, M. Heubeck and S. Schmitt Roddy Mavor and Matt Parsons, Seabirds and Cetaceans, Joint Nature Conservation Committee, Dunnet House, 7 Thistle Place, Aberdeen, AB10 1UZ Martin Heubeck, Shetland Oil Terminal Environmental Advisory Group, Department of Zoology, University of Aberdeen, Tillydrone Avenue, Aberdeen, AB9 2TN Sabine Schmitt, Research Department, Royal Society for the Protection of Birds, The Lodge, Sandy, Bedfordshire, SG19 2DL Cover painting of black-legged kittiwakes by David Bennett. Cover design by statusdesign.co.uk Further information on JNCC publications can be obtained from: JNCC, Monkstone House, City Road, Peterborough PE1 1JY Published by Joint Nature Conservation Committee, Peterborough Copyright: Joint Nature Conservation Committee 2006 ISBN-13 978 1 86107 585 7 ISBN-10 1 86107 585 5 ISSN 0963 8083 Seabird numbers and breeding success, 2005 This report should be cited as follows: Mavor, R.A., Parsons, M., Heubeck, M. and Schmitt, S. 2006. Seabird numbers and breeding success in Britain and Ireland, 2005. Peterborough, Joint Nature Conservation Committee. (UK Nature Conservation, No. 30.) Original data from the report may not be used in other publications (although general results and conclusions may be cited) without permission of JNCC, RSPB and/or SOTEAG, as relevant. Requests to use data should be channelled through S. Schmitt/RSPB (petrels, terns and skuas), M. Heubeck/SOTEAG (cliff-breeding species and black guillemots in Shetland) or Roddy Mavor/JNCC (other species/regions). Where necessary, such requests will be forwarded to other contributing organisations or individuals. 2 Contents Contents Page no. Summary 4 1 Introduction 5 1.1 The Seabird Monitoring Programme and Seabird Colony Register 5 1.2 Data presentation and methods 6 2 General features of the 2005 breeding season 12 3 Species accounts 13 3.1 Red-throateddiver Gavia stellata 13 3.2 Northernfulmar Fulmarus glacialis 15 3.3 Manxshearwater Puffinus puffinus 21 3.4 Europeanstorm-petrel Hydrobates pelagicus 22 3.5 Leach'sstorm-petrel Oceanodroma leucorhoa 22 3.6 Northerngannet Morus bassanus 23 3.7 Greatcormorant Phalacrocorax carbo 25 3.8 Europeanshag Phalacrocorax aristotelis 30 3.9 Arcticskua Stercorarius parasiticus 35 3.10 Greatskua Stercorarius skua 37 3.11 Mediterraneangull Larus melanocephalus 40 3.12 Black-headed gull Larus ridibundus 41 3.13 Mewgull Larus canus 44 3.14 Lesser black-backed gull Larus fuscus 47 3.15 Herringgull Larus argentatus 50 3.16 Great black-backed gull Larus marinus 54 3.17 Black-leggedkittiwake Rissa tridactyla 57 3.18 Sandwichtern Sterna sandvicensis 66 3.19 Roseatetern Sterna dougallii 70 3.20 Common tern Sterna hirundo 72 3.21 Arctictern Sterna paradisaea 77 3.22 Littletern Sterna albifrons 82 3.23 Common guillemot Uria aalge 87 3.24 Razorbill Alca torda 93 3.25 Blackguillemot Cepphus grylle 98 3.26 Atlanticpuffin Fratercula arctica 101 4 Acknowledgements 103 5 Bibliography 104 5.1 Referencesused in this report 104 5.2 Recent publications relevant to breeding seabirds in Britain and Ireland 107 3 Seabird numbers and breeding success, 2005 Summary Some findings of particular note in 2005 are summarised below: Red-throated diver breeding success was close to, or above, average at the majority of sites monitored, although all nests on Coll failed due to bad weather. Northern fulmar numbers were stable in most regions between 2004 and 2005, although there was a large increase in NE Scotland and a large decrease in NE Ireland. Productivity was similar to 2004, despite complete failure at two colonies, and thus below the long-term UK mean. Surveys of both gannetries in the Channel Islands – Ortac and Les Etacs – found 2,547 and 4,862 AOS, respectively. Since 1999 numbers increased by 41% on Les Etacs but remained stable on Ortac. The UK and Ireland gannet population has increased by 13% to 262,066 AOS since 1994-95. In response to a late winter/early spring wreck great cormorant and European shag numbers decreased in many eastern regions and, for shag, also in NW Scotland. Productivity of shags in Shetland and N and SE Scotland was particularly low, possibly due to birds failing to attain adequate breeding condition. After 12 years of decline, the number of Arctic skua territories increased, although numbers remain low. There was a marked increase in Shetland, where the number of great skua territories also increased, but both species decreased in Orkney. Skuas were more productive than in 2004, despite a scarcity of sandeels. Mediterranean gulls numbered at least 224 pairs. Breeding success was high, at 1.26 chicks fledged per pair. Black-headed and mew gulls increased in most regions. Some large mixed colonies of lesser black-backed and herring gull have declined substantially in recent years. At most gull colonies breeding success was low to moderate in 2005. Once again, mink depressed the productivity of four gull species in NW and SW Scotland. Breeding success of black-legged kittiwake was higher than in 2004, but still well below average for the UK and Ireland. Apparently low food availability early in the season resulted in late nest building at several colonies but conditions improved, allowing many birds to breed successfully. However, low success in NW Scotland and complete failure in N Scotland was attributed to low food availability there. Sandwich tern numbers were stable between 2004 and 2005. Birds were generally successful, with the exception of those nesting in Scotland. Overall roseate tern numbers were stable between 2004 and 2005. Notable increases were recorded on Coquet Island and at Lady’s Island Lake. Productivity was high at the majority of colonies. Common tern numbers increased slightly, with large increases in NE and SE Ireland, but a substantial decrease occurred in NE Scotland. Colonies adjacent to the Irish Sea were the most productive. Food availability problems probably depressed productivity in west and north Scotland and England, with predation also a factor at some English colonies. The number of Arctic terns in Shetland and Orkney recovered from the declines in 2004, with increases noted in most other regions. Breeding success was higher than in 2004, although only marginally so in the Northern Isles, probably due to low food availability. Colonies in NE England and Wales were very productive. Little tern numbers increased substantially in SE Ireland, where the most successful colony was situated. Elsewhere, breeding success in England and Wales was low, due to localised food availability problems, tidal inundation and predation, but productivity in Scotland was higher than in the previous five years. Common guillemot and razorbill numbers in sample plots increased (or at least remained stable) in northern and eastern regions and in Wales, with decreases in NW and SW Scotland. Whole-colony counts were broadly in line with these changes but, in addition, notable decreases occurred in NW England (razorbill only) and NE Ireland. For both species, breeding success was higher than in 2004 but still markedly below the long-term mean. Colonies in the north of Britain were generally less successful than others. Black guillemot numbers in Shetland and Orkney were stable between 2004 and 2005. However, numbers have halved in Orkney since 1986, although there has been no net change in Shetland over this period. 4 Introduction 1 Introduction This is the seventeenth annual report on the results of seabird monitoring at colonies throughout Britain and Ireland, produced jointly by JNCC, RSPB and SOTEAG, as part of JNCC's Seabird Monitoring Programme. Available data on seabird breeding numbers and breeding success at seabird colonies in 2005 are summarised and compared with results from previous years, primarily 2004, with an analysis of longer term trends in the context of recent findings. The information contained in this report has been collated from many sources. These include research staff and wardens from a variety of organisations including RSPB, SOTEAG, JNCC, Scottish Natural Heritage, English Nature, Countryside Council for Wales, Irish National Parks and Wildlife Service, the Wildlife Trusts, bird observatories, National Trust and National Trust for Scotland, the Centre for Ecology and Hydrology and BirdWatch Ireland. Many dedicated fieldwork volunteers also contribute valuable data to the Seabird Monitoring Programme; refer to the Acknowledgements section for details. One aim of the annual report is to draw attention to notable changes in seabird numbers or breeding performance, which may merit direct conservation action or further research. It is also intended to provide feedback and, we hope, encouragement for future work, to the many individuals and organisations contributing data, by placing results for individual colonies or regions in a wider context. The results presented refer mainly to coastal or island populations of seabirds, but reference is also made to inland populations of great cormorants, gulls and terns where data are available. Any comments on this report, or offers of help for future years, would be greatly appreciated by the authors. We are also keen to receive any existing additional information on numbers or breeding success for any seabird species, whether at coastal or inland colonies, which may not have been previously submitted to the Seabird Monitoring Programme. Any such data will be added to the long- term seabird databases maintained by JNCC and RSPB, including the JNCC/Seabird Group Seabird Colony Register. Details of recommended methods for assessing seabird numbers and breeding success are given in the Seabird monitoring handbook for Britain and Ireland (Walsh et al. 1995). Copies of the Handbook, or other advice on seabird monitoring methodology, may be obtained from the Seabirds and Cetaceans Unit of JNCC at the address given on the title page. 1.1 The Seabird Monitoring Programme and Seabird Colony Register The JNCC's Seabird Monitoring Programme facilitates the co-ordination of seabird monitoring on a UK-wide basis.

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