In California, a common winter resident October through March on larger bays, estuaries, and occasionally on emergent wetlands of central and northern California. Does not breed in California, although a few remain through summer. In winter, frequents large, coastal waters with abundant plant and animal life, but usually avoids mudflats. In wintering areas, feeds extensively on mollusks, crustaceans, and insects. In breeding season, eats more vegetation.
Flocks move away from boats when hunted.
Nests on open sites, with good visibility and easy access to water. No additional data found. Requires sheltered, mostly large bays and inshore waters. In California, rarely occurs on fresh water. Yearlong, diurnal activity.