Molt Migration of Scoters at Cape Peirce, Alaska

Abstract

There is presently little specific information on the molt migrations of scoters in the Nearctic. We conducted migration watches from 21 June to 31 July 1984 (total of 96 h) and from 5 to 15 July 1985 (total of 36 h) during daylight hours to estimate abundance and species composition of scoters engaged in a molt migration at Cape Peirce, southeast Bering Sea, Alaska. We counted 22,897 scoters moving west past the observation site in 1984, the year in which we probably made observations over most of the migration period. Allowing for daylight hours without watches, an estimated 66,500 scoters passed in 1984. Peak passage occurred on 11 July in both years. Species composition of migrants in 1984 was approximately 77% white-winged scoters (Melanitta fusca), 12% surf scoters (M. perspicillata), and 11% black scoters (M. nigra). Most of the migrants were adult males, probably migrating from breeding grounds in Interior Alaska. Our findings suggest that a large and presently undescribed molting area of white-winged scoters exists somewhere in the waters of western Alaska or eastern Siberia.

Key words: scoters, seaducks, molt migration, Cape Peirce, Togiak National Wildlife Refuge, Bering Sea, Alaska