(Histrionicus histrionicus), a bird of the family Anatidae. Length, approximately 45 cm; weight, 500– g. The bill is short, the tail is pointed and gradated, and there is a large paddle on the hind digit. The plumage is slate black, with a brightly colored head. The harlequin duck is found in the mountains of Asia (Eastern Siberia) and North America (northwest), as well as along the Atlantic coast of North America and the Greenland and Iceland coasts. It nests near mountain rivers, and winters near rocky sea coasts. The clutch contains four to eight eggs. The harlequin duck feeds on crustaceans, mollusks, and aquatic insects. It is of little commercial significance.