Migration of King, Somateria spectabilis, and Common, S. mollissima v-nigra, eiders past Point Barrow, Alaska, during spring and summer/fall 1996

Abstract

We counted migrating King (Somateria spectabilis) and Common (S. mollissima v-nigra) eiders at Point Barrow, Alaska, during spring and summer/fall 1996. During spring (1 May to 2 June), we estimated that 371 451 (95% C.I. ± 109 093) King and 72 606 (95% C.I. ± 13 824) Common eiders passed Point Barrow eastbound. During summer/fall (10 July to 16 October), we estimated a passage of 507 667 (95% C.I. ± 84 680) King and 111 635 (95% C.I. ± 42 440) Common eiders westbound. Our estimates provide evidence that both populations may have declined since 1976. Many King Eiders were observed in September and October suggesting that 1996 was a productive year. Migration counts during late fall at Point Barrow may provide a means to monitor King Eider production. King Eiders appeared at Point Barrow in early May but the peak of Common Eider migration occurred later. During summer/fall migration, most male and many female King Eiders migrated out of the Beaufort Sea to molt, whereas approximately 75% of the Common Eiders molted before migrating past Point Barrow in September and October. King Eiders comprised 85% to 90% of the identified eider migration, Common Eiders comprised most of the rest, and very small numbers of Spectacled (Somateria fischeri) and Steller's eiders (Polysticta stelleri) were seen.