Status of Red-throated Divers Gavia stellata in Britain in 2006

Capsule The population of Red-throated Divers in Britain increased between 1994 and 2006. Aim To determine the population size and distribution of Red-throated Divers in Britain for comparison with the previous national survey in 1994. Methods All freshwater bodies in Shetland, Orkney and two Special Protection Areas (SPAs) in the Hebrides were censused for Red-throated Divers. A stratified sample of 5-km squares was surveyed throughout the rest of the range. Two visits were made to all suitable habitats, at least 2 weeks apart, between 15 May and 31 July. Results The British breeding population of Red-throated Divers was estimated to be 1143 breeding pairs, although around 12% of adults recorded as non-breeding may actually have bred. Thus, a corrected estimate was calculated giving 1255 (95% CI 1014-1551) pairs. The total population of adults was estimated to be 4146 (95% CI 3430-4992). Shetland held 33% and the Outer Hebrides 26% of the breeding population. The estimated breeding population and total population of adults increased significantly, by 34% and 38% respectively, since the first national survey in 1994. The population remained stable in Shetland and Orkney, but there was a significant increase across the remainder of the range. Conclusion The breeding population of Red-throated Divers in Scotland has increased significantly since the last survey in 1994, as has the total number of adults. While the population in the Northern Isles remained stable, there was a significant increase in the breeding and total population away from the Northern Isles.