|Anas||albogularis||OR||Andaman Is., Cocos Is.|
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. 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. 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.
|wingspan min.:||60||cm||wingspan max.:||67||cm|
|size min.:||37||cm||size max.:||47||cm|
|incubation min.:||24||days||incubation max.:||28||days|
|fledging min.:||53||days||fledging max.:||60||days|
tide line. All these wetlands had natural or man-made bunds for collecting rainwater which reduced salinity. This species selected a nesting site based on optimum water levels and availability of food for the young. Nesting success was high during the study (85%) as there were very few predators. However, poaching of eggs by
humans and predation by Water Monitor Lizards were the major causes of egg loss. Predation by raptors may also occur. Parents with ducklings spent most of their time in thick vegetation, coming into open water with sparse vegetation only for very short periods.
Video Andaman Teal
copyright: Josep del Hoyo
Andaman Teal Anas (gibberifrons) albogularis, endemic to the Andamans, is scarce and has recently declined, and is likely to have been affected by the tsunami because of its coastal distribution. This duck is usually treated as a subspecies of Sunda Teal Anas gibberifrons, but it has been proposed that it should be treated as a full species (this proposal is currently under review by the BirdLife Taxonomic Working Group)