An East Asian teal-like duck. Males are distinctive, with an iridescent head that flashes green and copper, a silvery body with distinct scalloping, extremely long curved tertials, long pale scapulars, and a triangular white throat patch outlined in dark green. Brownish females resemble female Gadwall but have a dark bill. Breeds in northern interior marshes and winters on rivers, lakes, and coastal wetlands, often in flocks with other ducks.