eWestern BirdsThe Quarterly Journal of Western Field Ornithologists
Vol. 45, No. 2
Western Field Ornithologists
First Occurrence of an Atlantic Common Eider (Somateria mollissima dresseri) in the Pacific Ocean
Kenneth P. Able, Alan Barron, Jon L. Dunn, Kevin E. Omland, and Larry Sansone
ABSTRACT: The circumpolar Common Eider (Somateria mollissima) has six or seven recognized subspecies, females of which differ in size, overall coloration, and bill characters. An adult female observed 20–29 November 2011 in the harbor at Crescent City, Del Norte County, California, was apparently not the Pacific subspecies, S. m. v-nigrum (Pacific Eider). We analyzed photographs, published information, and specimens, and the Crescent City bird’s intensely rufous plumage as well as qualitative and quantitative bill morphology, especially the distance from the tip of the frontal lobe to the proximal end of the nares divided by total bill length, indicated that it was an example of S. m. dresseri (American or Atlantic Eider), of the northwest Atlantic Ocean.