The Long-tailed Duck, known in North America as the Oldsquaw, Clangula hyemalis is a medium-sized sea duck.
Adults have white underparts. The male has a long pointed tail and a dark bill lighter near the tip. In winter, the male has a dark cheek patch on a mainly white head and neck, a dark breast and mostly white body. In summer, the male is dark on the head, neck and back with a white cheek patch. The female has a brown back and a relatively short pointed tail. In winter, the female's head and neck are white with a dark crown. In summer, the head is dark.
They are migratory and winter along the eastern and western coasts of North America, on the Great Lakes, coastal Europe and Asia. This is a gregarious duck, and will form large flocks at that time of year.
They feed by diving, swimming underwater. They mainly eat mollusks, crustaceans and some small fish. Although they usually feed close to the surface, they aare capable of diving to depths of 200 feet.
The males are vocal and have a musical yodelling call.