The Green-winged Teal is North America's smallest dabbling duck. Unlike many of this continent's other dabblers, this one does not breed extensively in the prairie pothole region of the central continent. Instead it is most abundant in river deltas and forest wetlands of Canada and Alaska, where it nests in dense cover, often in shrubs or sedges. A migrant along all the major flyways, this is the second most abundant duck taken by hunters in North America. Because its breeding areas are far from human activity, however, its numbers have remained high and are even increasing.
This teal has a wide variety of courtship displays which it performs in rapid succession. Individuals form monogamous pairs for one breeding season, but paired males also attempt forced extra-pair copulations. Males desert females during incubation, so the female must provide all incubation and parental care. On its wintering grounds this species often congregates in large flocks and may move from region to region if conditions are unfavorable. In some regions, it forages day and night. Throughout its range, insect larvae plus the seeds of grasses and sedges make up the bulk of its diet.
Worldwide there are three recognized subspecies of Green-winged Teal: Anas crecca carolinensis in North America, A. c. crecca in Eurasia, and A. c. nimia on the Aleutian Islands.