- Measure 19–24 inches (48–61 cm)
- Male black with bold white wing patches, white crescents around eyes, and yellow bill with black knob at base
- Females are dull brown, with two whitish facial spots and white wing patches
Breeds on large lakes; winters mainly on the ocean and on large coastal bays, but a few remain on lakes in the interior.
Five to 17 buff or pink eggs in a hollow lined with sticks and down, under a bush, or in a crevice near water, often on an island in a lake.
Breeds in Alaska and much of western and central Canada. Winters along coasts, from Alaska south to California and from Newfoundland south to Carolinas, rarely to Florida and Texas. Also in Eurasia.
Soft whistles and guttural croaks.
During migration, long irregular lines consisting of thousands of white-winged scoters move southward, just offshore and only a few feet above the waves. White-wings are the most abundant and widespread of the three scoters: there are over a million in North America. This species feeds chiefly on mollusks, which it collects from mussel beds at depths of 15 to 40 feet (five to 12 metres). These birds also feed on crabs, starfish, sea urchins, and some fish. Sociable birds, they gather in large flocks or rafts, both to feed and to sleep at night. Like all birds that dive and rest on the sea, they are vulnerable to oil spills.