Chestnut-breasted shelduck

Tadorna tadornoides (Jardine & Selby, 1828)

Order: Anseriformes

Family: Anatidae

New Zealand status: Native

Conservation status: Vagrant

Other names: mountain duck, Australian shelduck, chestnut-coloured shelduck, chestnut shelduck, mountain shelduck, grunter, chestnut breasted shelduck, chestnutbreasted shelduck

Geographical variation: Nil

Chestnut-breasted shelduck. Adult female. Snares Islands, December 1984. Image © Colin Miskelly by Colin Miskelly

Chestnut-breasted shelduck. Adult female. Snares Islands, December 1984. Image © Colin Miskelly by Colin Miskelly

The chestnut-breasted shelduck is a frequent visitor to New Zealand. It is closely related to the endemic paradise shelduck with which it shares many plumage features. Chestnut-breasted shelducks often fly several hundred kilometres between breeding sites (used in winter and spring), to moulting sites, where they congregate in large numbers. Although apparently faithful to its nesting locations, the place where moult occurs can vary from year to year. Until the 1970s, it was known in Australia as the mountain duck, but is now most commonly referred to there as the Australian shelduck.

Identification

The chestnut-breasted shelduck is a large, mostly dark duck with a striking chestnut breast, white neck ring, and chestnut and green speculum. Females have a white eye-ring, and white at the base of the bill. The chestnut breast is darker on the female. The white neck ring of the male is often more sharply demarcated than that of the female. When seen together in pairs, the smaller size of the female is apparent. In flight, the white underwing and forewing are conspicuous, with the same pattern as the paradise shelduck.

Voice: a series of honks and grunts, similar to paradise shelduck, often very vocal, loud and harsh. The female’s call is higher in pitch than the male.

Similar species: the chestnut-breasted shelduck is most similar to a male paradise shelduck, from which it can be distinguished by the bright and conspicuous chestnut breast and white neck ring, and in the case of female chestnut-breasted shelduck, the white eye-ring and white at base of bill. Note also the dark undertail coverts (these are chestnut in paradise shelducks).

Distribution and habitat

Chestnut-breasted shelducks are largely confined to south-west and south-east Australia. They are spreading northwards in the west of their range, possibly as a result of favourable changes in its habitat due to land-clearing. Chestnut-breasted shelducks disperse widely from their breeding sites, and apart from vagrancy to New Zealand, were recorded on Norfolk Island in the 1980s. They use a wide variety of habitats, including brackish water (and even the sea occasionally), farmland, woodland, crops, irrigation areas, and stubble. Most New Zealand sightings have been on lowland wetlands, often with paradise shelducks.

New Zealand records

Chestnut-breasted shelducks were first recorded from New Zealand in 1973 at Hokitika River. There was an influx during 1982-86, with some birds persisting for several years, especially in Marlborough. They have been recorded regularly if infrequently since 2000. Chestnut-breasted shelduck have reached nearly all of New Zealand's outlying island groups, with records from Raoul Island, Kermadec Islands (1994), Pitt Island, Chatham Islands (1998), Snares Islands (1984), Enderby Island, Auckland Islands (1983-84), and Campbell Island (1984-85). Most records have been of single birds, but occasionally up to three birds. There is one confirmed breeding record, from near Lake Tekapo, where a pair with half-grown young was seen in January 1985. Birds have been seen in most districts of the South and North Islands.

Behaviour and ecology

In Australia, chestnut-breasted shelducks can often be seen in flocks of up to 1,000 or more. Like paradise shelducks, they are typically wary and difficult to approach, but can become habituated to people in urban settings. They are very upright both on land where they graze at dawn and dusk, and on the water, where they sit very high. Although young birds dive frequently, adults only dive during their moulting period when they are flightless, or when injured or frightened. Chestnut-breasted shelducks usually breed in a down-lined cavity of a hollow tree-limb, but also sometimes in caves or burrows, and sometimes under vegetation. After leaving the nesting hollow, the flightless, downy young may aggregate in crèches of 20-40, or in extreme cases, a hundred birds.

Food

Chestnut-breasted shelducks can feed by grazing, dabbling or filtering. They consume tubers and other plant material, including of saltbush and samphire, along with a range of crustaceans, insects and molluscs. There are few New Zealand data.

Weblinks

http://ibc.lynxeds.com/species/australian-shelduck-tadorna-tadornoides

http://www.birdlife.org.au/bird-profile/australian-shelduck

http://en.wikipedia.org/wiki/Australian_Shelduck

http://www.birdsinbackyards.net/species/Tadorna-tadornoides

http://australianmuseum.net.au/Australian-Shelduck

References

Gill, B.J.; Bell, B.D.; Chambers, G.K.; Medway, D.G.; Palma, R.L.; Scofield, R.P. Tennyson, A.J.D.; Worthy, T.H. 2010. Checklist of the birds of New Zealand, Norfolk and Macquarie Islands, and the Ross Dependency, Antarctica (4th edn). Te Papa Press in association with the Ornithological Society of New Zealand, Wellington.

Guest, R.; Bell, B. 1989. Annual report of the Rare Birds Committee 1988-89. OSNZ News 51: 5.

Heather, B.D. 1987. The chestnut-breasted shelduck in New Zealand 1983-1986. Notornis 34: 71-77.

Marchant, S.J.; Higgins, P. (eds) 1990. Handbook of Australian, New Zealand and Antarctic birds. Vol. 1, ratites to ducks. Oxford University Press, Melbourne, Australia.

Pizzey, G. 2007. The field guide to the birds of Australia (8th edition). HarperCollins.

Riggert, T.L. 1977. The biology of the mountain duck on Rottnest Island, Western Australia. Wildlife Monographs: 52.

Slater, P. 1989. The Slater field guide to Australian birds (revised edition).Lansdowne.

Tennyson, A.J.D. 1998. Chestnut-breasted shelducks and other wetland birds at Tupuangi, Chatham Islands. Notornis 45: 226-228.

Veitch, C.R.; Miskelly, C.M.; Harper, G.A.; Taylor, G.A.; Tennyson, A.J.D. 2004. Birds of the Kermadec Islands, south-west Pacific. Notornis 51: 61-90.

Recommended citation

Griffin, P. 2013. Chestnut-breasted Shelduck. In Miskelly, C.M. (ed.) New Zealand Birds Online. www.nzbirdsonline.org.nz

Chestnut-breasted shelduck

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