Blue-winged Teal (Anas discors)

Blue-winged Teal

Subspecies

Genus	Species	subspecies	Region	Range
Anas	discors		NA	n, c

Genus

Anas is a genus of dabbling ducks. It includes mallards, wigeons, teals, pintails and shovelers in a number of subgenera. Some authorities prefer to elevate the subgenera to genus rank.[1] Indeed, as the moa-nalos are very close to this clade and may have evolved later than some of these lineages, it is rather the absence of a thorough review than lack of necessity that this genus is rather over-lumped. The phylogeny of this genus is one of the most confounded ones of all living birds. Research is hampered by the fact the radiation of the two major groups of Anas ? the teals and mallard groups ? took place in a very short time and fairly recently, roughly in the mid-late Pleistocene. Furthermore, hybridization may have long played a major role in Anas evolution, with within-subgenus hybrids regularly and between-subgenus hybrids not infrequently being fully fertile.[1] The relationships between species are much obscured by this fact, and mtDNA sequence data is of dubious value in resolving their relationships; on the other hand, nuclear DNA sequences evolve too slowly to resolve the phylogeny of the subgenus Anas for example. Some major clades can be discerned. For example, that the traditional subgenus Anas, the mallard group, forms a monophyletic (in the loose sense, i.e. non-holophyletic) group has never been seriously questioned by modern science and is as good as confirmed (but see below). On the other hand, the phylogeny of the teals is very confusing. For these reasons, the dabbling duck lineages more distantly related to mallard group (which includes the type species of Anas) than the wigeons should arguably be separated in their own genera. These would include the Baikal Teal, the Garganey, the spotted black-capped Punanetta group, and the shovelers and other blue-winged species. Whether the wigeons, which are very distinct in morphology and behavior, but much less so in mtDNA cytochrome b and NADH dehydrogenase subunit 2 sequences, should also be considered a distinct genus Mareca (including the Gadwall and Falcated Duck) is essentially the one remaining point of dispute as regards the question which taxa should remain in this genus and which ones should not.

Physical charateristics

The male breeding plumage has a blue-gray head with large white crescent behind bill. Cinnamon-brown body feathers, patterned with fine black marks. White patch on rear flank. Upper wing with light blue patch with white rear border. Back of wing iridescent green. In eclipse plumage its gray-brown overall, without white patches. Faint outline of white face crescent. The female is recognized by gray-brown overall, with small white area at base of bill. Bill dark. Light blue upper wing patch with narrow white border. Back of wing mostly brown, with little green. Juveniles are similar to adult female.

Listen to the sound of Blue-winged Teal

[audio:http://www.planetofbirds.com/MASTER/ANSERIFORMES/Anatidae/sounds/Blue-winged Teal.mp3]

Copyright remark: Most sounds derived from xeno-canto

wingspan min.:	63	cm	wingspan max.:	69	cm
size min.:	37	cm	size max.:	41	cm
incubation min.:	23	days	incubation max.:	27	days
fledging min.:	35	days	fledging max.:	27	days
broods:	1		eggs min.:	6
			eggs max.:	15

Range

North America : North, Central

Habitat

Blue-winged teal inhabit shoreline more often than open water and prefer calm water or sluggish currents to fast water. They inhabit inland marshes, lakes, ponds, pools, and shallow streams with dense emergent vegetation. In coastal areas, breeding occurs in salt-marsh meadows with adjoining ponds or creeks. Blue-winged teal use rocks protruding above water, muskrat houses, trunks or limbs of fallen trees, bare stretches of shoreline, or mud flats for resting sites.
Blue-winged teal winter on shallow inland freshwater marshes and brackish and saltwater marshes. These teals build their nests on dry ground in grassy sites such as bluegrass meadows, hayfields, and sedge meadows. They will also nest in areas with very short, sparse vegetation. Blue-winged teal generally nest within several hundred yards of open water; however, nests have been found as far as 1 mile (1.6 km) away from water. Where the habitat is good, they nest communally.

Reproduction

The onset of courtship among immature blue-winged teal often starts in late January or early February. In areas south of the breeding grounds, blue-winged teal are more active in courtship during the spring migration than are most other ducks. Blue-winged teal are among the last dabbling ducks to nest, generally nesting between April and mid May. Few nests are
started after mid-July. Time of nesting can vary from year to year as a result of weather conditions. Blue-winged teal generally lay 10 to 12 eggs. Delayed nesting and renesting efforts have substantially smaller clutches, averaging 5 to 6 eggs. Clutch size can also vary with the age of the hen. Yearlings tend to lay smaller clutches. Incubation takes 21 to 27 days. Blue-winged teal ducklings can walk to water within 12 hours after hatching but do not fledge until 6 to 7 weeks. Blue-winged teal are sexually mature after their first winter. During incubation, the drake leaves its mate and moves to
suitable molting cover where it becomes flightless for a period of 3 to 4 weeks.

Feeding habits

Blue-winged teal are surface feeders and prefer to feed on mud flats, in fields, or in shallow water where there is floating and shallowly submerged vegetation plus abundant small aquatic animal life. They mostly eat vegetative matter consisting of seeds or stems and leaves of sedge, grass, pondweed, smartweed, duckweed, widgeongrass, and muskgrass. The seeds of plants that grow on mud flats, such as nutgrass, smartweed, millet, and rice cut-grass are avidly consumed by this duck.One-fourth of the food consumed by blue-winged teals is animal matter such as mollusks, crustaceans, and insects.

Video Blue-winged Teal

httpv://www.youtube.com/watch?v=2_rp4Xo8Frg

Conservation

This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Breeds in North America, mainly in prairie region, from British Columbia east to Newfoundland, south to California, New Mexico, Texas, Tennessee, and North Carolina; locally further south. Exceptionally, pair (status unknown) bred Denmark 1986.
Some records probably refer to escapes, but at least 10 recoveries of ringed birds proving that transatlantic vagrancy does occur. Most records Britain and Ireland (annual). Also recorded in Iceland, Faeroes, Channel Islands, France, Belgium, Netherlands, Germany, Denmark, Norway, Sweden, Finland, Poland, Switzerland, Spain, Portugal, Balearic Islands, Italy, Greece, Egypt, Algeria, Morocco, Azores, Canary Islands.

Migration

Blue-winged Teal are highly migratory and are, for the most part, absent from the majority of North America during the cold months of the year. They winter more extensively in South America than any other dabbler. They begin migrating later in spring than other dabblers, with birds arriving on the coast as early as March, but mostly not before April and May. Single males arrive first, with pairs and unpaired females following. Males migrate again from mid-July to mid-August, moving to larger marshes to undergo their molt. Fall migration starts in early August, and most birds are gone by mid-October.

Distribution map

Blue-winged Teal distribution range map

Literature

Title Does choice of estimators influence conclusions
from true metabolizable energy feeding trials?

Author(s): Mark H. Sherfy and Roy L. Kirkpatrick

Abstract: True metabolizable energy (TME) is a measure of av..[more]..

Source: J Ornithol (2005) 146: 383-389

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