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

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