One of the more controversial systematic problems existing in the family Anatidae concerns the taxonomic rank and evolutionary relationships of the four species of eiders, which are currently considered by the American Ornithologists’ Union (1957) to comprise three genera (Somateria, Lampronetta, and Polysticta) in the diving duck subfamily Aythyinae. In 1945, however, Delacour and Mayr included the eiders in a single genus (Somateria) within the sea duck tribe Mergini. At present, Delacour (1959) considers the eiders a separate tribe, Somateriini, distinct from the other sea ducks, and placed near the dabbling duck tribe Anatini. The erection of this new tribe, and his recognition of Polysticta as a monotypic genus for the Steller Eider, was apparently the result of Humphrey’s (MS, Univ. Mich. ; 1958) anatomical studies. On the basis of both behavior and anatomy, I concluded (1960) that the most satisfactory taxonomic relegation of the eiders is to consider them part of the tribe Mergini, as originally proposed by Delacour and Mayr, but to accept two genera, Somateria and Polysticta. Woolfenden (1961), after examining the postcranial osteology of all four species of eiders, came to identical conclusions.
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