Silver Teal (Anas versicolor)

Silver Teal

Subspecies

Monotypic species

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

Dorsal head (eye upward) and hindneck brown/black, lower sides of head pale buff, throat and sides of neck buff with fine black speckling, breast and cranial (fore) flanks buff with dark brown spotting, caudal flanks boldly barred. Rump, tail and coverts and abdomen vermiculated dark grey and white; upperparts brown-black with buff feather edging (mantle and scapulars), tertials dark brown, elongated. Wings grey, greater coverts broadly white-tipped, secondaries metallic green/blue with subterminal black and tipped white. Female is slightly duller, tertials shorter, barring on flanks less distinct, speculum less bright. Southern silver teal coarser brown not black-brown spotting and barring, flank barring whitish bars narrower, blackish brown bars wider.

Listen to the sound of Silver Teal

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

Copyright remark: Most sounds derived from xeno-canto

recorded by Alvaro Riccetto

wingspan min.:	0	cm	wingspan max.:	0	cm
size min.:	38	cm	size max.:	43	cm
incubation min.:	25	days	incubation max.:	26	days
fledging min.:	50	days	fledging max.:	60	days
broods:	4		eggs min.:	6
			eggs max.:	10

Range

South America : South. The Silver Teal is distributed from central Peru to Tierra del Fuego.

Habitat

It can be found in a variety of freshwater wetland types, and usually nests in shoreline vegetation.

Reproduction

Breeding period begins mainly October-November in the south, September to March in Peru. This species forms strong pair bonds. The nest is built on the ground, in waterside reedbeds and long grass by female only; lined with down. Up to 4 clutches a year, usually with 6-10 eggs which are incubated by the female for about 26 days. The youg fledge after 8 weeks and are tended for by both parents.

Feeding habits

Forages mainly by dabbling, head-dip and up-end in shallow water, occasionally dives for food. Diet consists of seeds and vegetative parts of aquatic plants, aquatic insects and their larvae, molluscs, crustaceans.

Video Silver Teal

httpv://www.youtube.com/watch?v=tS863rVcFns

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). The population trend appears to be stable, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is very 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.

Migration

It is partially migratory with some of the southernmost birds moving north to southern Brazil in the austral winter while there is also a resident breeding population in southern Brazil

Distribution map

Silver Teal distribution range map

Planet of Birds