Requires lakes and rivers with clear water and abundant fish. In winter, uses coasts and bays. Some nocturnal activity during migration. In North America, migrates in flocks of 5-15 by coastal and inland routes between breeding grounds in tundra and boreal forests and Atlantic, Gulf, and Pacific coasts. Probably does not renest.
Broods often combine to form large groups.
Predation on eggs by ravens has been reported. Eggs and nestlings taken by weasels, skunks, foxes, and snakes. Adults may be preyed upon by a variety of raptors. Ducks, geese, and swans of North America. Stackpole Books, Harrisburg, PA. 544pp.