Green-winged teal

The green-winged teal was formally described in 1789 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae. He placed it with the other ducks, geese and swans in the genus Anas and coined the binomial name Anas carolinensis. Gmelin based his description on the "American teal" that had been described in 1785 by John Latham in his A General Synopsis of Birds and in the same year by Thomas Pennant in his Arctic Zoology . The genus name Anas is Latin for "duck". The specific epithet carolinensis means "of Carolina". The species is monotypic, with no subspecies accepted. Some authorities treat the green-winged teal as a subspecies of the Eurasian teal (Anas crecca); when lumped, the merged species is known as common teal. ==Description==

This is the smallest North American dabbling duck. The breeding male has finely barred gray flanks and back, with pale yellow under the tail at the 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 Eurasian teal (the Eurasian relative of this bird) by a vertical white stripe on side of breast, the lack of a horizontal white scapular stripe, and thinner or even no buff lines between the green and brown pattern on its head. • Length: • Wingspan: • Weight: ==Distribution and habitat==

The American green-winged teal breeds from the Aleutian Islands, northern Alaska, Mackenzie River delta, northern Saskatchewan, Manitoba, Ontario, Quebec, and Labrador south to central California, central Nebraska, central Kansas, southern Minnesota, Wisconsin, Ontario, Quebec, Newfoundland, and the Maritime Provinces. They prefer shallow waters and small ponds and pools during the breeding season. They are often found resting on mudbanks or stumps, or perching on low limbs of dead trees. These ducks nest in depressions on dry ground located at the base of shrubs, under a log, or in dense grass. The nests are usually from water, but they avoid treeless or brushless habitats. Green-winged teal winter in both freshwater or brackish marshes, ponds, streams, and estuaries. As they are smaller birds, they tend to stay in the calmer water. In northern areas of the United States, green-winged teal migrating to wintering grounds appear in early September through mid-December. They begin migrating into most central regions during September and often remain through December. On their more southerly winter areas, they arrive as early as late September, but most do not appear until late November. ==Behavior and ecology==

Breeding Green-winged teal are among the earliest spring migrants. They arrive on nesting areas almost as soon as the snow melts. In early February, green-winged teal begin to depart their winter grounds, and continue through April. In central regions green-winged teal begin to arrive early in March with peak numbers in early April. Nesting chronology varies geographically. In North Dakota, green-winged teal generally begin nesting in late April. In the Northwest Territories, Canada, green-winged teal begin nesting between late May and early July. At Minto Lakes, Alaska, green-winged teal initiate nesting as early as 1 June and as late as 20 July. They become sexually mature after their first winter. The nest is usually concealed both from the side and from above in heavy grass, weeds, or brushy cover. Cattails, bulrushes, smartweeds (Polygonum spp.), and other emergent vegetation provide hiding cover for ducks on water. The clutch size ranges from 5 to 16 eggs. The incubation period is 21 to 23 days. The young fledge 34 to 35 days after hatching or usually before 6 weeks of age. Young green-winged teal have the fastest growth rate of all ducks. The males leave the females at the start of incubation and congregate on safe waters to molt. Some populations undergo an extensive molt migration while others remain on or near breeding grounds. Females molt on breeding grounds. Food and feeding Green-winged teal, more than any other species of duck, prefer to seek food on mud flats. Where mud flats are lacking, they prefer shallow marshes or temporarily flooded agricultural lands. They usually eat vegetative matter consisting of seeds, stems, and leaves of aquatic and emergent vegetation. Green-winged teal appear to prefer the small seeds of nutgrasses (Cyperus spp.), millets (Panicum spp.), and sedges to larger seeds, but they also consume corn, wheat, barley, and buttonbush (Cephalanthus spp.) seeds. In marshes, sloughs, and ponds, green-winged teal select the seeds of bulrushes, pondweeds, and spikerushes (Eleocharis spp.). To a lesser extent they feed upon the vegetative parts of muskgrass (Chara spp.), pondweeds, widgeongrass (Ruppia maritima), and duckweeds (Lemna spp.). They will occasionally eat insects, mollusks, and crustaceans. Sometimes during spring months, green-winged teal will gorge on maggots of decaying fish which are found around ponds. ==Predators==

Common predators of green-winged teal include humans, skunks (Mephitis and Spilogale spp.), red foxes (Vulpes vulpes), raccoons (Procyon lotor), crows, and magpies (Pica spp.). ==Relationships==

mtDNA data-wise, this species is more closely related to the speckled teal than to the Eurasian teal. is that the American lineage is derived from stray Eurasian teals, with the founder effect/genetic drift and/or hybrid introgression phenomena applying as above, only in the reverse direction for the former two. Still, this would require loss of sexual dimorphism in the ancestors of the speckled teal, but while extremely rare in dabbling ducks, it is not per se impossible. The close relationship of speckled and green-winged teals suggested by mtDNA data could of course still apply to the taxa in general, not just to sequences in two maternally inherited genes in a few individual ducks (for which it without doubt does apply), but the overall failure of Johnson & Sorenson to seriously take hybridization into account and their small sample sizes and obsolete conceptions of Indian Ocean biogeography do not help at all to resolve the issue, but in 1999, the methodology and interpretation were reasonable enough and in fact, the study was pioneering in many respects due to dense taxon-level sampling and still represents one of the default references for interpreting the phylogeny of the genus. The post-copulatory displays of the common and green-winged teal are identical, but those of the speckled teal have some additional elements. A firm conclusion cannot be reached at present beyond a tentative rejection of the phylogeny suggested by the mtDNA data. Nuclear DNA sequence information is required, but may not be sufficient, to resolve the puzzling relationships in the crecca-carolinensis-flavirostris complex of teals. ==References==