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.:||130||cm||wingspan max.:||150||cm|
|size min.:||48||cm||size max.:||53||cm|
|incubation min.:||30||days||incubation max.:||33||days|
|fledging min.:||60||days||fledging max.:||70||days|
Video Auckland Teal
copyright: Brooke Clibbon
The total area of the seven islands is 113 km2 but, with the exception of Disappointment Island, birds were predominantly dispersed along island shorelines, but now occur throughout Adams Island at least. It formerly bred on Auckland Island itself, where there are records from the 1940s. Three population estimates suggest that total numbers do not exceed 600 individuals, three indicate numbers of more than 1,000, and one suggests a population of more than 2,000 birds. The population appears to be stable. Introduced cats and pigs caused its extinction on Auckland Island. The accidental introduction of mammals to the remaining island populations could cause further local extinctions but it is unlikely to affect all sub-populations simultaneously. The introduction of avian disease is also considered a significant potential threat.