Unique Arctic sea duck. Much smaller than other eiders (and in a different genus); only slightly larger than Harlequin Duck. Male is unmistakable with bold black-and-white pattern, olive smudge in front of eye, and peachy underparts. Female less dazzling, chocolate brown overall with few markings; note square head, bold white edges on inner wing feathers, and white underwings. Breeds on Arctic tundra, mainly in Russia but also into Alaska. Winters in pairs or flocks in coastal waters, mainly along the Aleutians and far eastern Russia, also in northern Europe. Dives underwater for crustaceans and mussels.