Mendocino Co. Rare and local inland in winter on lacustrine and riverine waters, and found regularly in southern California only along the Colorado River. Feeds principally on animal foods, mainly mollusks and crustaceans in saltwater, and aquatic insects and crustaceans in freshwater, but also eats fish eggs and young. Also eats algae and the seeds, leaves, and stems of other aquatic plants.
Juvenile eats almost entirely aquatic invertebrates, mostly insects.
Also gleans food from submerged plants. In daytime, rests in feeding areas, or if very windy, seeks sheltered waters. Usually nests in a tree or snag cavity, often the deserted nest-hole of a pileated woodpecker or flicker, the latter necessarily being enlarged by decay. Also uses nest boxes and, where tree cavities are unavailable, rock crevices or buildings, or even nests under bushes. Nest is near a lake or quiet river.