Appearance. The green-winged teal is the smallest duck in North America, typically measuring 15 inches long and weighing less than a pound. Males in breeding plumage have a chestnut-red head with large green patches that extend from the eyes and join at the back of the neck. The male's pinkish-brown chest is flecked with black. A white bar separates the male's chest from gray flanks; the undertail is black. Female green-winged teal are a camouflaged mix of browns and tans, similar to other female puddle ducks. Both sexes have a small black bill, gray legs, and metallic green wing patches. A bright white belly is usually visible when green-winged teal are in flight.

Range and Habitat. Green-winged teal have a large breeding range that extends from western Alaska east across all Canadian provinces and northern states from Montana to Maine. Green-winged teal breed as far south as Iowa and Nebraska. They winter in the southern and coastal United States, Central America, and the northern Caribbean. Year-round populations are found in western Washington and from northern California east to Colorado and Wyoming. Green-winged teal are also found in Greenland, Iceland, and northern Europe.

In North America, green-winged teal breed in large numbers in the boreal forest and in deciduous parklands. In Minnesota they nest predominantly in the state's western prairies and northern forests. They prefer shallow, permanent wetlands with emergent vegetation.

Behavior. Green-winged teal migrate slowly. In the autumn, they often linger in the north until freeze-up, and most do not arrive in their wintering grounds until late November. They move north leisurely in spring, arriving in their more southerly breeding areas from mid-April to early May. Green-winged teal arrive in northern breeding areas as late as the third week of May.

Green-winged teal typically reach sexual maturity at age one. They select mates while on the wintering grounds or during northward migration. Most females are paired by the time they reach their nesting areas.

Green-winged teal are upland nesters and prefer very dense cover. The female lays a clutch of about seven eggs in a ground nest she constructs of grasses, lined with her own feathers. Incubation lasts 20 to 23 days. The male departs as soon as incubation begins. Green-winged teal ducklings can dive, walk, and feed a few hours after hatching.

Status. North America's green-winged teal population appears to have been increasing since the late 1950s. This trend may be due to abundant nesting habitat as most green-winged teal breed north of major agricultural areas. A 2016 U.S. Fish and Wildlife Service report placed the population at 4.3 million—the agency's highest ever count for the species.