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Seabird Species

Australasian Gannet

BM Dyer1 & LG Underhill1
1Marine and Coastal Management, Private Bag X2, Rogge Bay, 8012, South Africa
2Animal Demography Unit

  Australasian Gannet
Photo Les Underhill
Australasian Gannet, Black Reef, Cape Kidnappers, New Zealand

The Australasian Gannet breeds in small dense colonies at islands and along the coastline of southeastern Australia, Tasmania and New Zealand, and also at Norfolk Island. There are about 30 breeding sites, and several new gannetries have been initiated in recent years. In 1980 the total breeding population was estimated to be about 53 000 pairs, of which 80% bred at gannetries in New Zealand. Numbers at Tasmanian colonies have declined. It is the least abundant of the three species of gannet, but is not regarded as threatened. The range of nonbreeding birds covers the southern, eastern and western coasts of Australia, roughly as far north as the Tropic of Capricorn, the coast of New Zealand, and the ocean between New Zealand and Australia. It occurs as a vagrant on some Southern Ocean islands, in South Africa, Namibia and Brazil.

The first records of an Australasian Gannet in the African sector of the Southern Ocean were made on Marion Island, where one gannet was caught and ringed. This bird was also recorded on the Crozet Islands, farther east.

  Australasian Gannet
Photo Les Underhill
Gannets on outcrop at Black Reef, Cape Kidnappers, New Zealand

The first record anywhere along the coastline of Africa was made on 25 January 1982, when Rodney Cassidy recorded one in the Cape Gannet colony at on Bird Island, Lamberts Bay. He reported his observation in the journal Ostrich "I saw an Australian Gannet landing in the Cape Gannet colony. The bird was identified by a considerably shorter gular stripe than that of the Cape Gannet, white outer tail feathers and black secondaries. It was also noted that the call was much higher pitched than that of the Cape Gannet. The bird was not proven to breed with any Cape Gannet." This bird was ringed with SAFRING ring number 9-06535.

The second African record was made at Malgas Island. An adult was first recorded on 23 November 1987, and then seen at regular intervals at an empty nest site until 21 February 1988, and was observed for the last time for that breeding season on 19 April 1988. The period from November to April is the peak breeding season for the Cape Gannet, when birds are most numerous at the breeding colonies. This bird was seen for the last time on 24 July 1989.

By 1999, eight Australasian Gannets had been recorded at Malgas Island, three of which had been more or less regularly resighted. Even the original Lamberts Bay bird, ringed as 9-0635 in 1982, turned up on Malgas Island, on 25 October 1989. An Australasian Gannet which had first been recorded on Malgas Island on 16 December 1989 (ringed 9-61382), paired with a Cape Gannet in 1994 (which had previously been ringed 9-19370); it was observed incubating a single egg in this breeeding season, but the outcome of the breeding attempt is unknown. In 1997, in its fourth breeding season using the same nest site each year, it was observed with a large downy chick on 9 December. The chick was ringed 9A-05180. On 24 February 1998, the chick was fully feathered. The plumage was paler than that of a Cape Gannet chick, and the length of the gular stripe was intermediate between that of a Cape Gannet and an Australasian Gannet. This mixed pair also produced a chick (ring 9A-22222) in the 1998/1999 breeding season; this chick was last seen fully feathered on 16 April 1999, and is presumed to have fledged successfully.

The first sighting of an Australasian Gannet on Bird Island, Algoa Bay, was made on 15 March 1990. By 1999, there had been three more records from this island. One of these, ringed 9A-02253 on 25 December 1996, was retrapped on Malgas Island on 11 November 1997.

The first (and still the only) Namibian record was from Ichaboe Island, which lies 30 km north of Luderitz. The distinctive higher-pitched call alerted Bruce Dyer to the presence of an Australasian Gannet, and then bird was located, identified by its darker eye, short gular stripe and white outer tail feathers. It was ringed 9-87201 on 23 November 1993.

To summarize. By the end of 1999, Australasian Gannets had been recorded at each of the three South African breeding colonies of Cape Gannets; the number of records of different birds was approaching 20. Of the three Cape Gannet colonies in Namibia, the Australasian Gannet has been recorded at one, Ichaboe Island. Most of these vagrants were ringed. Amazingly, this ringing has demonstrated that two of this small handful of birds have moved between islands.

It has been observed on several Southern Ocean islands: There is a single record for South America, in southern Brazil, from the Moleques do Sul Islands (27 51S 48 26W). This bird had presumably crossed both the Indian and Atlantic Oceans.

Key references

  • Bege LAR, Pauli BT 1990. Two birds new to the Brazilian avifauna. Bulletin of the British Ornithologists' Club 110: 93-94.
  • Berruti A 1988. A second record of the Australasian Gannet Morus serrator in South Africa, and notes on its identification. Cormorant 16: 59-60.
  • Brown CR, Oatley TB 1982. Bird ringing at Marion and Prince Edward Islands, 1977-1982. South African Journal of Antarctic Research 12: 45-48.
  • Cassidy RJ 1983. The Australian Gannet in African waters. Ostrich 54: 182.
  • Dyer BM 1990. Eight new records of the Australasian Gannet Morus serrator in South Africa. Marine Ornithology 18: 60-64.
  • Dyer BM 1995. First record of an Australasian Gannet Morus serrator in Namibia. Marine Ornithology 23: 158.
  • Dyer BM, Upfold L, Kant W, Ward VL 2001. Breeding by and additional records of Australasian Gannet, Morus serrator, in South Africa. Ostrich 72: 124-125.
  • Lequette, Betr## Judas 1995. Australian and Cape Gannets at Saint Paul Island. Emu 95: 134-137.
  • Ryan PG 1997. Australian Gannet Morus serrator. In: Harrison JA, et al. (eds) The atlas of southern African birds. Vol. 1. Johannesburg: BirdLife South Africa: 763
Cape Kidnappers, New Zealand
Photo Les Underhill
 
Australasian gannet
Photo Les Underhill
The Australasian Gannet colony at Cape Kidnappers, Hawkes Bay, North Island, New Zealand. This is a mainland breeding colony. The photograph was taken in August, during the nonbreeding season, when relatively small numbers of gannets were present in the colony.