The Pacific black duck (Anas superciliosa), commonly known as the PBD, 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 in New Zealand, where it is also known by its Māori name, .

Taxonomy

thumb|Watercolour made by [[Georg Forster on James Cook's second voyage to the Pacific Ocean. This painting is the holotype for the species.]]

The Pacific black duck was formally described in 1789 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae. He placed it with all the other ducks, geese and swans in the genus Anas and coined the binomial name Anas superciliosa. Gmelin based his description on the "Supercilious duck" that had been described in 1785 by the English ornithologist John Latham in his A General Synopsis of Birds. The naturalist Joseph Banks had provided Latham with a water-colour drawing of the duck by Georg Forster who had accompanied James Cook on his second voyage to the Pacific Ocean. His picture was drawn at Dusky Sound, a fiord on the southwest corner of New Zealand. This picture is the holotype for the species and is now held by the Natural History Museum in London. The genus name Anas is the Latin word for a duck. The specific epithet superciliosa is from Latin meaning "supercilious" or "eye-browed", a reference to the prominent supercilium or eye-stripe.

Two subspecies are now recognised:

  • A. s. pelewensis Hartlaub & Finsch, 1872 – island black duck, breeds on the southwest Pacific islands and northern New Guinea
  • A. s. superciliosa Gmelin, JF, 1789 − Australasian duck, breeds in Indonesia, southern New Guinea, Australia and New Zealand, where it is known as the grey duck or pārera.
  • Anas superciliosa × platyrhynchos (Pacific Black Duck × Mallard)

A third subspecies, rogersi from Australia, has sometimes been recognised but it not distinguishable either genetically or phenotypically from the nominate race.

Behaviour

Breeding

The nest is usually placed in a hole in a tree, but sometimes an old nest of a corvid is used and occasionally the nest will be placed on the ground. The clutch of 8–10 pale cream eggs is incubated only by the female. The eggs hatch after 26–32 days. The precocial downy ducklings leave the nest site when dry and are cared for by the female. They can fly when around 58 days of age.

Feeding

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. This same impact is occurring in many areas of Australia, Tasmania and Adelaide in particular.

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 is not correct; it appears that the mallard phenotype is dominant, and that the degree to which species contributed to a hybrid's ancestry cannot be determined from the plumage.