Everything about The Pacific Black Duck totally explained
The
Pacific Black Duck,
Anas superciliosa is a
dabbling duck found in much of
Indonesia,
New Guinea,
Australia,
New Zealand, and many islands in the southwestern Pacific, reaching to the
Caroline Islands in the north and
French Polynesia in the east. It is usually called the Grey Duck or Pārera in New Zealand.
This sociable
duck is found in a variety of wetland habitats, and its nesting habits are much like those of the
Mallard, which is encroaching on its range in New Zealand (Rhymer & Simberloff 1996). It feeds by upending, like other
Anas ducks.
It has a dark body, and a paler head with a dark crown and facial stripes. In flight it shows a green
speculum and pale underwing. All plumages are similar. The size range is 54-61 cm; males tend to be larger than females, and some island forms are smaller and darker than the main populations. It isn't resident on the
Marianas islands, but sometimes occurs there during migration. The now-
extinct Mariana Mallard was probably originally derived from hybrids between this species and the
mallard, which came to the islands during migration and settled down there.
There are three subspecies of
Anas superciliosa:
rogersi breeds in Indonesia, New Guinea and Australia,
pelewensis on the southwest Pacific islands, and
superciliosa in New Zealand. The New Zealand subspecies has declined sharply in numbers, at least in its pure form, due to competition from and hybridisation with the introduced mallard (Gillespie, 1985). Rhymer
et al. (1994) say their data "points to the eventual loss of identity of the Grey Duck as a separate species in New Zealand, and the subsequent dominance of a hybrid swarm akin to the 'Mariana Mallard.'"
It was assumed that far more mallard drakes mate with Grey Duck females than vice versa based on the fact that most hybrids show a mallard-type plumage, but this isn't correct; It appears that the mallard phenotype is
dominant, and that the degree to which species contributed to a hybrid's ancestry can't be determined from the plumage (Rhyner
et al. 1994). The main reasons for displacement of the Pārera seem to be physical dominance of the larger mallards, combined with a marked population decline of the Pārera due to overhunting in the mid-20th century (Williams & Basse 2006)
Gallery
Image:Pacific black duck bibra wa gnangarra.jpg
Image:Pacific Black Duck.jpg
Image:Anas superciliosa (Pacific Black Duck).jpg
Further Information
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