Crested tern

Sterna bergii Lichtenstein, 1823

Order: Charadriiformes

Family: Sternidae

New Zealand status: Native

Conservation status: Vagrant

Other names: swift tern, great crested tern, greater crested tern, yellow-billed tern

Geographical variation: Four subspecies are recognised, the form recorded from New Zealand is S. b. cristata . It breeds in Southeast Asia, Indonesia, Australia, and the western and central Pacific east to the Tuamotu Archipelago.

Crested tern. Breeding adult. Michaelmas Cay, January 2017. Image © Imogen Warren by Imogen Warren

Crested tern. Breeding adult. Michaelmas Cay, January 2017. Image © Imogen Warren by Imogen Warren

The crested tern is a large, distinctive, yellow-billed tern that is common in Australia but seen only rarely in New Zealand. A crested tern was apparently resident around Wellington for about 15 years from the early 1980s, and was seen regularly in Wellington Harbour, and at Pukerua Bay and Waikanae Estuary.

Identification

This tern is unmistakable if seen clearly. Its large size combined with its prominent yellow bill is unique in the New Zealand area. The species is grey above and white below with a black cap and a deeply forked tail. In breeding plumage, the black feathers on its nape form a small shaggy crest. In non-breeders the black on the crown recedes and is streaked with white. Juveniles have a more smudgy crown, black tips to many of their upper feathers and a less deeply forked tail. The legs and feet are black. The species has a rakish yet graceful appearance in flight .

Voice: whistles, harsh guttural or short sharp cries; the common flight call is kerrak.

Similar species: the crested tern is about half the size of a Caspian tern, which has a prominent red bill. Smaller terns are readily separable by size and most have either a red or black bill. Little terns and fairy terns sometimes have yellow or orange coloured bills but are much smaller (50-70 g). Lesser crested terns (Sterna bengalensis) have never been recorded from New Zealand but occur in northern Australia so they might reach New Zealand; they are smaller with a more orange-coloured bill (Higgins & Davies 1996).

Distribution and habitat

The crested tern has a wide distribution from South Africa to the Persian Gulf, and through South-east Asia and Indonesia to Australia and Polynesia. New Zealand birds are believed to be of the form that occurs from South-east Asia east to the Tuamotu Archipelago.  Crested terns are considered to be sedentary, but after breeding, birds sometimes disperse. It is primarily a coastal species, often seen on islands, at estuaries, or in harbours roosting on beaches, rocks or objects such as jetties. It is sometimes seen further out to sea, but is rarely found inland.

New Zealand records

The crested tern is a rare vagrant to New Zealand with 13 records only. The first record was from the Kermadec Islands in 1910. Since the 1960s the species has been reported from Spirits Bay, Waipu, Auckland, Firth of Thames, Maketu, Napier, New Plymouth, Manawatu, Wellington, Farewell Spit, Kaikoura and in Canterbury (off Southshore Spit and at Washdyke Lagoon). One was apparently resident around Wellington from 1981-1995.

Behaviour and ecology

Crested terns nest in dense colonies, with seasonal patterns varying between sites. They are gregarious, however all New Zealand records have been of single birds, often associating with white-fronted terns.

Food

Crested terns mainly eat fish, occasionally prawns and squid. They occasionally scavenge offal from boats; there is no information on diet from New Zealand. Most feeding is in coastal waters, with prey caught by the birds plunging and briefly submerging; they occasionally skim feed.

Websites

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

http://www.birdlife.org/datazone/speciesfactsheet.php?id=3263

References

Heather, B.D.; Robertson, H.A. 2000 (revised edition). The field guide to the birds of New Zealand. Viking: Auckland.

Higgins, P.J.; Davies, S.J.J.F. (eds.) 1996. Handbook of Australian, New Zealand and Antarctic birds. Vol. 3, snipe to pigeons. Oxford University Press: Melbourne.

Miskelly, C.M.; Crossland, A.C.; Sagar, P.M.; Saville, I.; Tennyson, A.J.D.; Bell, E.A. 2017. Vagrant and extra-limital records accepted by the Birds New Zealand Records Appraisal Committee 2015-2016. Notornis 64: 57-67.

Tennyson, A.J.D. 2010. Lari. Pp. 223-243. In Checklist Committee (OSNZ) 2010. Checklist of the birds of New Zealand, Norfolk and Macquarie Islands, and the Ross Dependency, Antarctica (4th edn). Ornithological Society of New Zealand & Te Papa Press, Wellington.

Todd, K. 1981. A crested tern in Hawkes Bay. Notornis 28: 262.

Recommended citation

Tennyson, A.J.D. 2013 [updated 2017]. Crested tern. In Miskelly, C.M. (ed.) New Zealand Birds Online. www.nzbirdsonline.org.nz

Crested tern

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Crested tern

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