Trends in populations of red-legged Kittiwake Rissa brevirostris, a Bering Sea endemic

Abstract

The Red-legged Kittiwake Rissa brevirostris is a small gull which is restricted to four breeding locations, all in the Bering Sea (Pribilof Islands, Bogoslof Island, Buldir Island, and the Commander Islands). In the mid-1970s, when the earliest counts were made at most sites, approximately 260,000 birds were present at breeding colonies. Subsequent counts indicated that populations at Bogoslof and Buldir had increased by the early 1990s. Data for the Commander Islands were inadequate to make strong conclusions about trends but there were no indications of substantial change between the 1970s and 1990s. In contrast, Red-legged Kittiwakes have declined in the Pribilof Islands by approximately 50% since the mid-1970s, a matter of concern because this island group once contained more than 80% of the world's population. Research is needed to determine causes for declines in Red-legged Kittiwakes and population monitoring should continue to provide a basis for conservation measures.