Distribution, Abundance, Population Structure and Productivity of Tundra Swans in Bristol Bay, Alaska

Data on tundra swans (Cygnus columbianus columbianus) were obtained on the northern Alaska Peninsula from 1983 to 1987. Phenology was advanced 2-4 weeks of swan nesting areas in the Subarctic and Arctic, but a late spring retarded nesting by at least ten days. The highest densities of potential breeders (0.3-0.9 swans.km-') occurred along the lowland coast and in broad drainage basins. Estimates of the breeding population ranged from 4000 to4600 swans. Brood sizes in August ranged from 2.7 2 0.3 SE to 3.3 2 0.5 young. In summer, 5 1-66% of the adults and subadults were observed as potential breeders, and the remainder were in nonbreeding flocks. Between 31 and 40% of the observed pairs had nests or young. The population and production on the Alaska Peninsula may be less affected by weather than populations at higher latitudes.