Australasian gannet: where and when to see them

The Australasian gannet is a large white seabird of New Zealand and southern Australia, recognised by its golden head, pointed bill and black flight feathers. Dense breeding colonies can occupy conspicuous coastal headlands and offshore islands. Adults range widely over surrounding seas in search of schooling fish. Its streamlined shape reflects an aerial hunting lifestyle, while accessible colony viewpoints offer opportunities to study courtship, nesting and chick development without entering breeding ground.

Size

84–91 cm long

Weight

2.3–3 kg

Lifespan

20–30 years

Status

Least Concern

Gannets breed in crowded colonies where pairs defend small nest territories using calls, bill gestures and ritualised displays. Both adults incubate the egg and feed the chick. Offshore, birds search from the air and plunge into the sea after prey, often forming feeding gatherings. Young birds disperse after fledging, and many New Zealand juveniles cross the Tasman Sea. Adults typically show strong attachment to established breeding colonies and return for successive nesting seasons. Courtship rituals involve head-shaking and mutual preening, reinforcing pair bonds before and during nesting. Parents take turns fishing and guarding the chick, which remains in the nest for an extended fledging period. Post-breeding dispersal sees young birds undertake significant journeys, with many making a trans-Tasman crossing before returning to breed as adults.

• Parents incubate the egg using their highly vascularised feet.
• A typical breeding attempt involves just one egg.
• Many juveniles from New Zealand disperse to Australian waters.
• Young birds begin with dark, speckled plumage and whiten over several years.

New Zealand colonies are generally most rewarding from spring through summer, with many birds present between September and February. Some colonies remain active later as chicks develop. Exact timing and public access differ, so use current colony information rather than assuming year-round attendance. Prime viewing opportunities from a ship's deck often occur as birds commute to and from offshore feeding grounds, particularly during the breeding season. Many colonies are protected reserves, so visitors must adhere to specific viewing guidelines during the breeding months. Early morning or late afternoon can sometimes offer particularly active colony scenes.

Breeding colonies occupy exposed headlands, rocky islands and coastal platforms with open flight access. Feeding habitat is mainly productive coastal and continental-shelf water. Suitable land viewpoints exist at some New Zealand colonies, but cliffs, unstable terrain and seasonal access restrictions limit others. Nests are typically built on flat ground or slight inclines on the chosen platforms, often utilizing available vegetation or guano to form a shallow cup. The availability of suitable, predator-free nesting sites is a crucial factor limiting colony expansion. They are pelagic outside the breeding season, ranging widely over coastal waters.

Schooling fish, including pilchards, anchovies, garfish and other locally abundant species, provide most food. Squid may also be taken. Adults swallow prey at sea and later regurgitate meals to chicks, whose growth depends on repeated deliveries from the surrounding marine environment. Their diet can vary geographically depending on local prey abundance and species distribution. While primarily fish, they are opportunistic hunters and will exploit other marine organisms if available. Chicks grow rapidly, consuming large quantities of fish, which can sometimes lead to visible 'fish runs' where adults return with full crops.

Common name

Australasian gannet

Scientific name

Morus serrator

Animal group

Birds

Size

84–91 cm long

Weight

2.3–3 kg

Lifespan

20–30 years

Status

Least Concern

Identification

Its black central tail feathers distinguish it from the white-tailed northern gannet and the much more extensively black-tailed Cape gannet. Adult Australasian gannets have a distinctive buff-yellow wash on the head, which is particularly prominent during the breeding season. Immature birds exhibit a mottled brown and white plumage, gradually acquiring adult coloration over several years. Their large size and powerful, conical bill are also key identification features at all ages.