Both sexes look like a dark-colored female Mallard. Bill of male is dull yellowish; bill of female is mottled orange and black, like a typical Mallard. In flight, bright white underwings contrast with dark body. Note distinct white stripe in front of iridescent panel on upperwing, compare to Mottled Duck (limited range overlap). Usually in pairs or small flocks; wary in most areas, but in some city parks and urban settings has become fairly tame. In some areas of sw. US, hybridizes with Mallard, producing birds with variably intermediate features.