A tiny, squat, and pale duck with a short, dark bill. Males have a white body with black wings, a black breast band, and a black cap that become glossy black in the breeding season. Females are duller with a thin stripe through the eye. Females lack the male’s breast band and have a brown cap and wings. In flight, females have thin white edges on the trailing edge of the wings while males have big white slashes on the wings. They inhabit water bodies with floating vegetation and nest in holes in trees.