Status of Breeding Common Scoter Melanitta nigra nigra in Britain and Ireland in 1996: The Effect of the Sea Empress Oil Spill dataset https://portal.medin.org.uk/portal/start.php?tpc=007_NRW_DS110113 Following concerns regarding potential effects of the Sea Empress oil spill in Carmarthen Bay, February 1996, on the British and Irish populations of breeding Common Scoters Melanitta nigra nigra, their status and distribution were determined from a survey in May - June 1996. The survey was undertaken in five areas (Shetland, the Flow country, West and South Scotland, Islay and Ireland), using methods devised during the first complete British and Irish census of this species in 1995. Survey effort was concentrated on sites that held Common Scoters in 1995, and on sites with historical records. The survey visited 223 sites and located 376 birds. This was 79 fewer birds than the previous year, a 17% decline in numbers (16% in Ireland and 19% in Britain), a 19% decrease in occupied 10-km squares and a 31% decrease in occupied sites, compared to visits made at a similar time in 1995. It is possible that a decline of this magnitude may be within the range of natural population fluctuations or it could be due to the late arrival of birds after the late spring in 1996. However, over the last eight years, the number of Common Scoters in the Flow country has declined by 42% from an estimated 48 pairs in 1988 to only 28 in 1996. Given the Common Scoter's threatened status in the UK, that the dynamics of the population are unknown, and the potential decline, annual monitoring of both numbers and productivity is a high priority. Data used to assess the potential effects of the Sea Empress oil spill in Carmarthen Bay, February 1996, on the British and Irish populations of breeding Common Scoters Melanitta nigra nigra. 19960831