The adult is 39-56 cm (15-22 in) long with a 71-84 cm (28-33 in) wingspan and is at 726-1,360 g. It has a blue bill and yellow eyes. The male has a dark head with a green sheen, a black breast, a light back, a black tail, and a white underside. The drake or male is larger and has a more rounded head. Its belly and flanks are a bright white. Its neck, upper chest, and tail feathers are a glossy black, while its lower flanks are gray. The adult female has a white band and brown oval shaped patches at the base of the bill, which is a slightly duller shade of blue than the drake's bill. Females have grey on both their legs and feet. They have a brown body and head, with white bands on their wingtips. Juveniles look similar to adult females.


Habitat and Distribution

This bird spends summer in Alaska, Siberia and northern Europe. It is also found in Asia, and in the Aleutian Islands year round.The summer habitat is marshy lowland tundra and islands in fresh water lakes. They winter along the Pacific and Atlantic coasts of North America, the coasts of northwest Europe, the Caspian Sea, the Black Sea, the coast of Japan, Yellow Sea and East China Sea. During the winter, they are found in coastal bays, estuaries, and sometimes inland lakes, such as the lakes of Central Europe and the Great Lakes.


Feeding

The Scaup dive to obtain food, which they eat on the surface. They mainly eat mollusks, aquatic plants, and aquatic insects. In summer they will eat aquatic crustaceans.


Breeding

Pairs nest in close proximity to each other in large colonies, usually near water, on an island or shoreline, or on a raft of floating vegetation. The nest consists of a shallow depression made by the female and lined with her down. After the female lays the eggs, the male abandons the female. Once the male leaves the female, they go to a large, isolated lake, in order to molt. The female lays six to nine olive-buff colored eggs, which she incubates for 24-28 days.


Calls and Songs

Female Scaup have a single pitch, a raspy ?arrr-arrr-arrr-arrr-arrr? sounding vocalization.