The Green-winged Teal (Anas carolinensis or Anas crecca carolinensis) is a common and widespread duck that breeds in the northern areas of North America except on the Aleutian Islands. It was considered conspecific with the Common Teal (A. crecca) for some time but the issue is still being reviewed by the American Ornithologists’ Union; based on this the IUCN and BirdLife International do not accept it as a separate species at present. However, nearly all other authorities consider it distinct based on behavioral, morphological, and molecular evidence. The scientific name is from Latin Anas, “duck” and carolinensis, “of Carolina”.
This dabbling duck is strongly migratory and winters far south of its breeding range. It is highly gregarious outside of the breeding season and will form large flocks. In flight, the fast, twisting flocks resemble waders.
This is the smallest North American dabbling duck. The breeding male has grey flanks and back, with a yellow rear end and a white-edged green speculum, obvious in flight or at rest. It has a chestnut head with a green eye patch. It is distinguished from drake Common Teals (the Eurasian relative of this bird) by a vertical white stripe on side of breast, the lack of both a horizontal white scapular stripe and the lack of thin buff lines on its head.
The females are light brown, with plumage much like a female mallard. They can be distinguished from most ducks on size, shape, and the speculum. Separation from female Common Teal is problematic.
In non-breeding (eclipse) plumage, the drake looks more like the female.
It is a common duck of sheltered wetlands, such as taiga bogs, and usually feeds by dabbling for plant food or grazing. It nests on the ground, near water and under cover. While its conservation status is not evaluated by IUCN at present due to non-recognition of the taxon, it is plentiful enough to make it a species of Least Concern if it were; it is far more plentiful than the Common Teal. It can be seen in vast numbers in the Marismas Nacionales of western Mexico, a main wintering area.
This is a noisy species. The male has a clear whistle, whereas the female has a feeble quack. [Wikipedia]
The little Green-winged Teal is the smallest dabbling duck in North America. The natty male has a cinnamon-colored head with a gleaming green crescent that extends from the eye to the back of the head. In flight, both sexes flash deep-green wing patches (specula). Look for them on shallow ponds and in flooded fields, and listen for the male’s decidedly non-ducklike whistle. These common ducks breed along northern rivers; wintering flocks can number as many as 50,000. [All About Birds]
Green-winged Teal Facts [All About Birds]
The American and Eurasian forms of the Green-winged Teal were formerly considered different species. The Eurasian teal differ from the American by lacking the vertical white shoulder stripe and having a horizontal white stripe along the back instead. Eurasian teal show up casually each year along both the Pacific and Atlantic coasts.
Green-winged Teals have closely spaced, comblike projections called lamellae around the inner edge of the bill. They use them to filter tiny invertebrates from the water, allowing the birds to capture smaller food items than other dabbling ducks.
Green-winged Teal sometimes switch wintering sites from year to year. One banding study found that individuals wintering in Texas one year went as far away as California in subsequent years. This lack of philopatry, or “faithfulness” to a particular site, may reflect the tendency of males that did not breed the year before to try to find mates among a different set of wintering females.
The oldest known Green-winged Teal was at least 20 years and 3 months, based on banding data. It was a female banded in 1941 in Oklahoma, and recovered by a hunter 1960 in Missouri.