The name is based on size rather than on relationships, so that several quite different groups of small ducks are called teal. In Britain the name signifies a species of which the American subspecies is called the common, or green-winged, teal. The male's brown head is slightly crested, and has a green patch from the eye to the nape. Both sexes have a green patch or speculum on the back edge of the wing. The blue-winged teal is found over most of North America from Alaska eastward in summer, and migrates as far as South America in winter.
Males have a dark-bluish head with a distinctive white crescent from forehead to chin.
A close relative, the cinnamon teal, breeds from western North America to South America. Males are a rich dark-chestnut color. The nearest relatives of these two are the several species of shoveler and the garganey of Eurasia. It lives in diverse freshwater habitats including woodland ponds, swamps, marshes, lakes, slow moving rivers, and forested wetlands. The northernmost populations migrate south in the winter.