Australasian Gannet
A species of Gannets Scientific name : Morus serrator Genus : Gannets
Australasian Gannet, A species of Gannets
Botanical name: Morus serrator
Genus: Gannets
Content
Description General Info
Description
An adult Australasian gannet is 84–91 cm (33–36 in) long, weighs 2.3 kg (5.1 lb), and has a 170–200 cm (67–79 in) wingspan. The two sexes are generally of a similar size and appearance, though a 2015 field study at Pope's Eye and Point Danger colonies found females to be 3.1% and 7.3% heavier respectively. Females also had a slightly larger ulna and smaller bill. The plumage is white with black flight feathers on the wings, and central rectrices of the tail. Some individuals have more extensive black plumage of their tail feathers. There is a sharp demarcation between light and dark plumage. Black primary feathers are more resilient to wear, which may explain the dark plumage of the wings. The head and hindneck are tinged buff-yellow. The colour is more pronounced on the head and during breeding season. The eyes have a light grey iris surrounded by a pale blue eye ring, and bare black skin on the face which merges into the bill. In adults, the bill is pearly grey with dark grey or black edges, and a black groove running down the length of the upper mandible. The four-toed feet are dark grey and joined by a membrane of similar colour. There are light green lines running along the ridges of the toes that continue along up the front of the legs. Fledglings are brownish-grey speckled with white overall. They have dark brown bills, bare facial skin and eyes, and dark grey legs and feet. Australasian gannets take 2–5 years to gain adult plumage. Over this period, the upperparts and underparts gradually whiten and the crown and nape become buff-coloured, but there is great variation in the age that mature plumage is seen. This species is distinctive and only likely to be confused with species that do not generally share its range. The Cape gannet is a rare vagrant to Australasian waters and has an all-black tail, while the masked and red-footed boobies are generally restricted to tropical waters. Although both have mostly white plumage, they lack the buff colouring of the head and have white tails. The masked booby has a blue-black face and less black on the wing, while the red-footed booby has red feet.
Size
91 cm
Colors
Black
Yellow
White
Life Expectancy
20 years
Feeding Habits
Australasian Gannet primarily feed on forage fish and cephalopods, diving from up to 20m to capture prey. They adjust their diet based on prey availability, favoring energy-dense pilchards or substituting with other fish such as anchovies when needed. Feeding near fishing vessels, they occasionally scavenge discarded catch.
Habitat
Australasian Gannet primarily inhabit marine environments, often seen over continental shelves and inshore waters, rarely venturing far from land. They breed on open offshore islets and select mainland sites that offer some degree of protection. Australasian Gannet's range encompasses broad oceanic regions in the Southern Hemisphere, with a particular affinity for areas associated with the continent where they are found. These birds are highly adapted to life at sea, though young may occasionally venture into harbors and bays, especially during storms.
Dite type
Piscivorous
General Info
Behavior
The Australasian gannet is generally solitary when out at sea, though once a bird has found fish to hunt, other gannets may notice and join it. It is gregarious on land, nesting in colonies. Non-breeding gannets often form groups on the outskirts of the colony. Small numbers of gannets may remain around the colony site outside of the breeding season, using it as a roosting site.
Distribution Area
The Australasian gannet is found from Steep Point in Western Australia along the southern and eastern Australian coastline to the vicinity of Rockhampton in Queensland as well as the North and South Islands of New Zealand Lord Howe and Norfolk Islands. At sea it is generally restricted to waters over the continental shelf and may enter harbours bays and estuaries particularly in stormy weather. Over fall and winter young gannets from New Zealand colonies disperse to the north and west mainly flying north around the North Island and (to a lesser extent) via the Cook Strait. They generally reach as far as southeastern Queensland and Rottnest Island in Western Australia. Far-wandering gannets are occasional visitors to Marion Island and the Crozet Islands in the southern Indian Ocean and have even reached South Africa where they have interbred with Cape gannets. Some immature gannets spend 3 to 4 years in Australian waters before returning to New Zealand while others remain in New Zealand waters.
Species Status
The International Union for the Conservation of Nature (IUCN) lists the Australasian gannet as a species of least concern as the population is large and appears to be growing. There are possible impacts from commercial fishing though this is probably low compared with other seabirds. Survival rates each breeding season can vary dramatically most likely due to food availability and weather. More frequent El Niño–Southern Oscillation events lead to warmer water in Bass Strait which gives rise to more fish and hence accounting for the increase in Australian waters. Gannets established a mainland colony on Young Nick's Head near Gisborne after decoys of nesting birds and pre-recorded calls were broadcast to passing gannets in spring 2008. Successful breeding was recorded at the site from the 2010–11 breeding season onwards. A similar effort to establish a colony on Mana Island led to the arrival of a single gannet dubbed Nigel "no mates" who lived alone among the 80 decoys for several years until he was found dead in summer 2018; in summer 2018 three more gannets arrived at the site. Gannets have been enticed to established breeding colonies by decoys at reserves on Motuora Island.
Scientific Classification
Phylum
Chordates Class
Birds Order
Gannets and Relatives Family
Sulids Genus
Gannets Species
Australasian Gannet