New Zealand swan | Matapu

Cygnus sumnerensis (Forbes, 1890)

Order: Anseriformes

Family: Anatidae

New Zealand status: Endemic

Conservation status: Extinct

Other names: pouwa

Geographical variation: Two subspecies: New Zealand swan C. s. sumnerensis, formerly throughout mainland New Zealand; Chatham Island swan C. s. chathamicus, formerly on the Chatham Islands.

 
 
 
New Zealand swan | Matapu. Chatham Island subspecies, composite skeleton (the skull is the holotype). Dominion Museum (now Te Papa). Image © Te Papa by Charles Lindsay

New Zealand swan | Matapu. Chatham Island subspecies, composite skeleton (the skull is the holotype). Dominion Museum (now Te Papa). Image © Te Papa by Charles Lindsay

Black swans are a common and prominent part of New Zealand’s wetland fauna today but the country once had its own endemic forms of swan that are now extinct.

In 1890, the Canterbury Museum’s Director, Henry Ogg Forbes, described Cygnus sumnerensis based on large swan bones found near Sumner, Christchurch. By 1998, based on a new detailed study of its size, the extinct New Zealand species was considered to be exactly the same as the living black swan.

However in 2017 new research, primarily using ancient DNA from museum bones, showed that Forbes had been correct. New Zealand did have a prehistorically extinct swan and, in fact, the Chatham Islands had another closely related subspecies. Former Dominion Museum (now Te Papa) Director, W.R.B. Oliver, had already provided a valid name for this Chatham form when he renamed Cygnus sumnerensis as Cygnus chathamicus (he had wrongly considered that Forbes’ description was inadequate). The 2017 study accepts one species of extinct swan with two subspecies: Cygnus sumnerensis sumnerensis and Cygnus sumnerensis chathamicus.

The ancestors of the New Zealand swan are thought to have colonised New Zealand 1-2 million years ago.

Identification

The colours of New Zealand’s extinct swan were not recorded so are unknown but, being a close relative of the black swan, perhaps it was similarly coloured. The extinct swan was considerably larger than the black swan, with a relatively more robust skeleton and longer legs. It weighed 6-10 kg compared with the black swan’s weight of 4-9 kg, so it was 20-32 % heavier. The Chatham subspecies was very similar to the mainland New Zealand form but had a less robust humerus and femur.

Voice: unknown.

Distribution and habitat

The species was found in prehistoric bone deposits, including swamp and dune sites, dating back several thousand years throughout New Zealand and on Chatham and Pitt Islands.

Population

Bones of both extinct swan subspecies are common in prehistoric bone deposits, indicating that the species was once common and widespread.

Threats and conservation

The swan became extinct on mainland New Zealand by about 1450 AD and by about 1650 AD on the Chatham Islands, quite soon after humans arrived in the country in the late 13th century. Remains of the species have been found in widespread archaeological food midden sites and its extinction was evidently due to over-hunting.

Breeding

Unknown; however, the black swan breeds on freshwater bodies where most breeders form monogamous pairs and defend territories. Black swans build nests made of large mounds of vegetation and lay an average of 5-6 eggs.

Behaviour and ecology

Due to the swan’s extinction several hundred years ago, nothing has been recorded about its ecology. Although its skeleton shows that it was capable of flight, it had a reduced flying ability compared with the black swan, so it probably had a more terrestrial lifestyle.

Food

There are no records of its food or feeding habits but it presumably had fairly similar behaviour to the black swan, eating soft plants taken underwater or grazed in swampy habitats.

Weblink

Te Papa blog: Another extinct bird: New Zealand's prehistoric swan

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 edition).  Ornithological Society of New Zealand & Te Papa Press, Wellington.

Gill, B.J.; Martinson, P. 1991. New Zealand’s extinct birds. Random Century, Auckland.

Millener, P.R. 1999. The history of the Chatham Islands’ bird fauna of the last 7000 years – a chronicle of change and extinction. Pp. 85-109 in Olson, S.L. (ed.). Avian Paleontology at the close of the 20th century: proceedings of the 4th international meeting of the Society of Avian Paleontology and Evolution, Washington, D.C., 4-7 June 1996. Smithsonian Institution Press, Washington, D.C.

Oliver, W.R.B. 1955 (2nd edition). New Zealand birds. A.H. & A.W. Reed, Wellington.

Rawlence, N.J.; Kardamaki, A.; Easton, L.J.; Tennyson, A.J.D.; Scofield, R.P.; Waters, J.M. 2017. Ancient DNA and morphometric analysis reveal extinction and replacement of New Zealand’s unique black swans. Proceedings of the Royal Society B, Biological Sciences.

Tennyson, A.J.D.; Bartle, J.A. (Sandy). 2008. Catalogue of type specimens of birds in the Museum of New Zealand Te Papa Tongarewa. Tuhinga – Records of the Museum of New Zealand Te Papa Tongarewa 19: 185-207.

Worthy, T.H. 1998. A remarkable fossil and archaeological avifauna from Marfells Beach, Lake Grassmere, South Island, New Zealand. Records of the Canterbury Museum 12: 79-176.

Recommended citation

Tennyson, A.J.D. 2022. New Zealand swan. In Miskelly, C.M. (ed.) New Zealand Birds Onlinewww.nzbirdsonline.org.nz

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