Pacific black duck
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Anseriformes
Family: Anatidae
Genus: Anas
Species:
A. superciliosa
Binomial name
Anas superciliosa
Gmelin, 1789
Subspecies

See text

Natural range of the Pacific black duck

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 in New Zealand, where it is also known by its Maori name, pārera.

Taxonomy

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.[2] 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.[3][4] 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.[5][6] 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.[7]

Two subspecies are now recognised:[8]

A third subspecies, rogersi from Australia, has sometimes been recognised but it not distinguishable either genetically or phenotypically from the nominate race.[9]

Description

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.[10] 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.[11] 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 there.

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.[12]

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.[13]

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.[14]

Conservation status

The Pacific black duck has declined sharply in numbers in New Zealand and several Australian islands due to competition from and hybridisation with the introduced mallard.[15] 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." Studies of their three species of parasitic feather lice support this prediction.[16] 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.[17] The main reasons for displacement of the grey duck seem to be physical dominance of the larger mallards, combined with a marked population decline of the grey duck due to overhunting in the mid-20th century.[18]

Various views and plumages

See also

References

  1. ^ BirdLife International (2016). "Anas superciliosa". IUCN Red List of Threatened Species. 2016: e.T22680217A92849931. doi:10.2305/IUCN.UK.2016-3.RLTS.T22680217A92849931.en. Retrieved 12 November 2021.
  2. ^ Gmelin, Johann Friedrich (1789). Systema naturae per regna tria naturae : secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis (in Latin). Vol. 1, Part 2 (13th ed.). Lipsiae [Leipzig]: Georg. Emanuel. Beer. p. 537.
  3. ^ Latham, John (1785). A General Synopsis of Birds. Vol. 3, Part 2. London: Printed for Leigh and Sotheby. p. 497, No. 45.
  4. ^ Mayr, Ernst; Cottrell, G. William, eds. (1979). Check-List of Birds of the World. Vol. 1 (2nd ed.). Cambridge, Massachusetts: Museum of Comparative Zoology. p. 472.
  5. ^ Medway, David G. (1976). "Extant types of New Zealand birds from Cook's voyages. Part 1: Historical and type paintings" (PDF). Notornis. 23 (1): 45-60 [54, "Grey duck"].
  6. ^ Lysaght, Averil (1959). "Some eighteenth century bird paintings in the library of Sir Joseph Banks (1743-1820)". Bulletin of the British Museum (Natural History), Historical Series. 1 (6): 251-371 [290, No. 77]. doi:10.5962/p.92313.
  7. ^ Jobling, James A. (2010). The Helm Dictionary of Scientific Bird Names. London: Christopher Helm. pp. 46, 374. ISBN 978-1-4081-2501-4.
  8. ^ Gill, Frank; Donsker, David; Rasmussen, Pamela, eds. (January 2022). "Screamers, ducks, geese & swans". IOC World Bird List Version 12.1. International Ornithologists' Union. Retrieved 4 July 2022.
  9. ^ a b "Grey duck | Pārera | New Zealand Birds Online". nzbirdsonline.org.nz. Retrieved 2022-06-24.
  10. ^ Rhymer, Judith M. & Simberloff, Daniel (1996). "Extinction by hybridization and introgression". Annual Review of Ecology and Systematics. 27: 83–109. doi:10.1146/annurev.ecolsys.27.1.83.
  11. ^ Madge, Steve; Burn, Hilary (1988). Waterfowl: an Identification Guide to the Ducks, Geese, and Swans of the World. Boston: Houghton Mifflin. ISBN 0-395-46727-6.
  12. ^ "Anas superciliosa, Pacific Black Duck". Museums Victoria Collections. Retrieved 2020-01-17.
  13. ^ Marchant, S.; Higgins, P.G., eds. (1990). "Anas superciliosa Pacific Black Duck" (PDF). Handbook of Australian, New Zealand & Antarctic Birds. Volume 1: Ratites to ducks; Part B, Australian pelican to ducks. Melbourne, Victoria: Oxford University Press. pp. 1320–1332. ISBN 978-0-19-553068-1.
  14. ^ "Pacific Black Duck". The Australian Museum. Retrieved March 6, 2019.
  15. ^ Gillespie, Grant D (1985). "Hybridization, introgression, and morphometric differentiation between Mallard (Anas platyrhynchos) and Grey Duck (Anas superciliosa) in Otago, New Zealand" (PDF). The Auk. 102 (3): 459–469. doi:10.1093/auk/102.3.459.
  16. ^ Bulgarella, M (2018). "The ectoparasites of hybrid ducks in New Zealand (Mallard x Grey Duck)". International Journal for Parasitology: Parasites and Wildlife. 7 (3): 335–342. doi:10.1016/j.ijppaw.2018.09.005. PMC 6154467. PMID 30258780.
  17. ^ Rhymer, Judith M.; Williams, Murray J. & Braun, Michael J (1994). "Mitochondrial analysis of gene flow between New Zealand Mallards (Anas platyrhynchos) and Grey Ducks (A. superciliosa)" (PDF). The Auk. 111 (4): 970–978. doi:10.2307/4088829. JSTOR 4088829.
  18. ^ Williams, Murray & Basse, Britta (2006). "Indigenous gray ducks, Anas superciliosa, and introduced mallards, A. platyrhynchos, in New Zealand: processes and outcome of a deliberate encounter". Acta Zoologica Sinica. 52 (Supplement): 579–582.
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