Pacific black duck

Appearance

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. 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 is not 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.

Status

There are three subspecies of "Anas superciliosa":
⤷  "A. superciliosa rogersi" Mathews, 1912 − Australasian duck, breeds in Indonesia, southern New Guinea and Australia
⤷  "A. superciliosa pelewensis" Hartlaub & Finsch, 1872 – Island black duck, breeds on the southwest Pacific islands and northern New Guinea
⤷  "A. superciliosa superciliosa" Gmelin, 1789 − New Zealand grey duck, breeds in New Zealand

Behavior

Like its relatives the mallard and American black duck, the Pacific black duck is one of a number of duck species that can quack, with the female producing a sequence of raucous, rapid quacking which decreases in volume.

Food

The Pacific black duck is mainly vegetarian, feeding on seeds of aquatic plants. This diet is supplemented with small crustaceans, molluscs and aquatic insects. Food is obtained by 'dabbling', where the bird plunges its head and neck underwater and upends, raising its rear end vertically out of the water. Occasionally, food is sought on land in damp grassy areas.