128 ORNIS SVECICA 20: 128–143, 2010 Abstract Introduction Of the eight species of geese (Anser and Branta) considered naturally occurring in the Western Pal- earctic region, 27 “populations” or “lyways” were deined in Madsen et al. (1999). Of these, 12 popu- lations occur in Britain and Ireland. Canada Geese Branta canadensis were introduced in Britain from the 17th century and, as a non-native species, are not considered in this review. Geese wintering in Britain and Ireland come from a wide breeding area including north west Canada, Greenland, Ice- land, Svalbard, Fennoscandia and northern Russia. The breeding areas are vast and generally inacces- sible and population assessments have traditionally taken place during the non-breeding season. Information on goose abundance and distribu- Trends in goose numbers wintering in Britain & Ireland, 1995 to 2008 Trender för antal gäss som övervintrar i Storbritannien och Irland 1995–2008 CARL MITCHELL, KENDREW COLHOUN, ANTHONY D. FOX, LARRY GRIFFIN, COLETTE HALL, RICHARD HEARN, CHAS HOLT & ALYN WALSH. Twelve migratory and native goose populations winter in Britain and Ireland and up to date information on their abundance and distribution is provided. Seven popula- tions are increasing: Barnacle Goose (Svalbard, current estimate 26,900 birds), Barnacle Goose (Greenland 70,500), Pink-footed Goose (288,800), North West Scot- land Greylag Goose (34,500), Re-established Greylag Goose (50,000), Light-bellied Brent Goose (East Cana- dian High Arctic 34,000) and Light-bellied Brent Goose (Svalbard 3,270). Two populations appear stable: Taiga Bean Goose (432 at two sites) and Icelandic Greylag Goose (98,300). Three populations are decreasing: Euro- pean White-fronted Goose (2,760) due to short stopping in mainland Europe, Dark-bellied Brent Goose (82,970), due to a recent population decline (due to poor breed- ing success) and short stopping, and Greenland White- fronted Goose (24,055) due to recent poor breeding success and, up to 2006, hunting. An estimated 120,000 migratory geese wintered in Britain and Ireland in 1960 compared to 500,000 in 2008. Despite many goose spe- cies demonstrating high degrees of site faithfulness (re- sponding to safe roosts and regular food supply), shifts in winter distribution of several goose populations have occurred (notably Icelandic Greylag Goose). Carl Mitchell, Colette Hall and Richard Hearn, Wild- fowl & Wetlands Trust (WWT), Slimbridge, Gloucester, GL2 7BT, UK. E-mail: carl.mitchell@wwt.org.uk. Kendrew Colhoun, Royal Society for the Protection of Birds (RSPB) Northern Ireland Ofice, Belvoir Park Forest, Belfast BT8 7QT, UK. Anthony D. Fox, Department of Wildlife Ecology and Biodiversity, National Environmental Research Institute, Aarhus University, Kalø, Grenåvej 14, DK-8410 Rønde, Denmark. Larry Grifin, WWT Caerlaverock, Dumfries & Gal- loway, UK. Chas Holt, British Trust for Ornithology (BTO), The Nunnery, Thetford, Norfolk, IP24 2PU, UK. Alyn Walsh, National Parks and Wildlife Service, Wild- fowl Reserve, North Slob, Wexford, Ireland. tion is important for four primary reasons: (i) in- ternational legislation and conventions to which the UK is a signatory require such information as evidence that the state of biodiversity is being maintained; (ii) for supporting site-based conserva- tion measures using the “1% criterion” (see Mad- sen et al. 1999); (iii) many geese are quarry species and international legislation requires hunting to be sustainable; (iv) many goose populations have be- come reliant on agricultural land, especially during the non-breeding season, which brings them into conlict with farmers (see Fox et al., this volume). This assessment updates abundance data since the review by Madsen et al. (1999) for geese belong- ing to the 12 populations that winter in Britain and Ireland.