Australasian Gannet

The Australasian gannet, known scientifically as Morus serrator and colloquially as the Australian gannet or tākapu, is a majestic seabird belonging to the Sulidae family. Adult Australasian gannets boast a predominantly white plumage with striking black flight feathers at the wingtips and trailing edge of the wing. The central tail feathers are also black. A distinctive buff-yellow tinge adorns the head, complemented by a pearly grey bill with dark grey or black edges and captivating blue-rimmed eyes. In contrast, juveniles display a mottled grey head and dark bill, with their plumage transitioning from mottled to white over five years until they reach full maturity.

Identification Tips

When identifying the Australasian gannet, look for the characteristic black markings on the wings and tail, the buff-yellow head, and the blue eye ring. The bill is grey with dark edges, and the legs are dark grey. Juveniles can be recognized by their mottled plumage and darker bill. This species is unlikely to be confused with others outside its range, such as the Cape gannet, which has an all-black tail, or the tropical masked and red-footed boobies, which lack the buff head coloring and have white tails.

Habitat

Australasian gannets are found over waters above the continental shelf, frequenting the southern and eastern Australian coastline, as well as the North and South Islands of New Zealand, Lord Howe, and Norfolk Islands. They may venture into harbors, bays, and estuaries, especially during stormy weather.

Distribution

The species ranges from Steep Point in Western Australia to Rockhampton, Queensland, and across the Tasman Sea to New Zealand and its surrounding islands. Young birds from New Zealand disperse widely, reaching as far as southeastern Queensland and Western Australia, with some even traveling to the southern Indian Ocean and South Africa.

Behaviour

Australasian gannets are solitary at sea but highly social on land, nesting in dense colonies. They are territorial during the breeding season, performing elaborate displays to defend their nests. Non-breeding individuals often congregate on the periphery of colonies, and some birds use the sites as roosting spots year-round.

Song & Calls

At sea, these birds are generally silent, but they become quite vocal in the colony, especially during the day and occasionally at night in the breeding season. Their calls, a harsh "arrah-arrah" or "urrah-urrah," serve as both a greeting and a threat.

Breeding

Australasian gannets form monogamous pairs, often lasting several seasons. They engage in intricate courtship displays, including bill fencing and allopreening. Breeding season varies by location, with nests built on flat ground or broad ledges, typically on offshore islands or mainland cliffs. A single pale blue egg is laid annually, with chicks hatching featherless but quickly growing a white down.

Similar Species

The Australasian gannet can be distinguished from the Cape gannet by its partially black tail and from the masked and red-footed boobies by its buff-yellow head and lack of white tail feathers.

Diet and Feeding

These birds are skilled plunge divers, hunting fish and squid that school near the ocean's surface. They adjust their diet based on availability, favoring energy-rich fish like pilchards but capable of switching to other species when necessary.

Conservation Status

The Australasian gannet is classified as Least Concern by the IUCN, with a growing population and few natural or man-made threats. Conservation efforts include establishing new colonies using decoys and recorded calls to attract gannets to suitable breeding sites.