53 cm (21") Uncommon; more numerous in West. Summers on forested lakes, rivers; winters on coastal estuaries, bays. Small diving duck.
Male: dark oval-shaped head may show glossy purple; short dark bill; white crescent in front of its bright yellow eye; white breast and sides; black back. In flight, very rapid with wings that whistle; white crescent patch on dark head; white areas on back and large white speculum area.
Female: dark brown head with steep vertical forehead; stubby bill; bright yellow eye; bill is mostly yellow-orange in western birds but dark with yellow tip in east; white neck collar; gray breast, back and sides. In flight, very rapid with wings that whistle; large white speculum area.
Song: harsh croak.