Salvin's prion, Pachyptila salvini known as medium-billed prion, is a species of seabird in the petrel family Procellariidae. Salvin's prion is a member of the Pachyptila genus, along with the blue petrel, they make up the prions, they in turn are members of the Procellariidae family, the Procellariiformes order. The prions are small and eat just zooplankton. First, they have nasal passages. Although the nostrils on the prion are on top of the upper bill; the bills of Procellariiformes are unique in that they are split into between 7 and 9 horny plates. They produce a stomach oil made up of wax esters and triglycerides, stored in the proventriculus; this is used against predators as well as an energy rich food source for chicks and for the adults during their long flights. They have a salt gland, situated above the nasal passage and helps desalinate their bodies, due to the high amount of ocean water that they imbibe, it excretes a high saline solution from their nose. Salvin's prion has two subspecies: Pachyptila salvini salvini, the nominate subspecies, breeds on Prince Edward Island and the Crozet Islands Pachyptila salvini macgillivray breeds on St. Paul Island and Amsterdam Island The name Pachyptila comes from the Greek words pakhus and ptilon.
Pakhus means "thick" or "stout" and ptilon means "a feather". From the Greek language, prion comes from the word priōn meaning "a saw", in reference to its serrated edges of its bill; the species is named for the British ornithologist Osbert Salvin. Salvin's prion is a small 29 cm petrel with grey and white plumage, a blue bill. Like the broad-billed prion it has lamellae in its bill; this small prion breeds colonially on a number of subantarctic islands in the southern Indian Ocean. The colonies of medium-billed prions are attended nocturnally; the nests are concealed in burrows dug into soil. Nests are attended for several months prior to breeding. A single egg is laid in November or early December, incubated for around 50 days. Both parents feed the chick once it is hatched; the chicks fledge around 60 days after hatching. The main components of its diet are amphipods and krill, although it will take fish and squid. In addition to filter feeding, food is obtained by hydroplaning. Salvin's prion breeds principally on Île aux Cochons in the Crozet Islands, where four million pairs are thought to breed.
Other breeding colonies include St Paul Island and Amsterdam Island. At sea they range from South Africa eastwards to New Zealand. Salvin's prion is not considered threatened with extinction. Although numbers have declined on some islands where rats and feral cats have been introduced, the world population is estimated at around 12 million birds, they are given a classification of Least Concern. BirdLife International. "Medium-billed Prion - BirdLife Species Factsheet". Data Zone. Retrieved 17 Jul 2009. Brooke, M.. "Procellariidae". Albatrosses And Petrels Across The World. Oxford, UK: Oxford University Press. ISBN 0-19-850125-0. Clements, James; the Clements Checklist of the Birds of the World. Ithaca, NY: Cornell University Press. ISBN 978-0-8014-4501-9. Double, M. C.. "Procellariiformes". In Hutchins, Michael. Grzimek's Animal Life Encyclopedia. 8 Birds I Ratites to Hoatzins. Joseph E. Trumpey, Chief Scientific Illustrator. Farmington Hills, MI: Gale Group. Pp. 107–111. ISBN 0-7876-5784-0. Ehrlich, Paul R.. The Birders Handbook.
New York, NY: Simon & Schuster. Pp. 29–31. ISBN 0-671-65989-8. Gotch, A. F.. "Albatrosses, Fulmars and Petrels". Latin Names Explained A Guide to the Scientific Classifications of Birds & Mammals. New York, NY: Facts on File. p. 192. ISBN 0-8160-3377-3. Maynard, B. J.. "Shearwaters and fulmars". In Hutchins, Michael. Grzimek's Animal Life Encyclopedia. 8 Birds I Ratites to Hoatzins. Joseph E. Trumpey, Chief Scientific Illustrator. Farmington Hills, MI: Gale Group. Pp. 123–133. ISBN 0-7876-5784-0. ZipCode Zoo. "Pachyptila salvini". BayScience Foundation. Archived from the original on 2012-06-09. Retrieved 26 Jul 2009
Subantarctic fur seal
The subantarctic fur seal is found in the southern parts of the Indian and Atlantic Oceans. It was first described by Gray in 1872 from a specimen recovered in northern Australia—hence the inappropriate specific name tropicalis; the subantarctic fur seal is medium in size compared with other fur seals. Males grow to 2 m and 160 kg, whereas females are smaller—1.4 m and 50 kg. Both sexes faces, their bellies are more brownish. Males have a dark grey to black back; the females are lighter grey. Pups are molt at about 3 months old; the snout is flat. The flippers are broad. Subantarctic fur seals live for about 20–25 years. Subantarctic fur seals are geographically widespread; as their name implies, they breed in more northerly locations than the Antarctic fur seals. The largest breeding colonies are on Gough Island in the South Atlantic and Île Amsterdam in the southern part of the Indian Ocean. Breeding grounds are found at Marion Island in the Prince Edward Islands, the Crozet Islands, Macquarie Island.
Where grounds overlap, the subantarctic species can be identified by the orange colour on the chest. About 300,000 of the species alive today substantially down from when they were first discovered in 1810, as they were hunted for their pelts throughout the 19th century. Populations are recovering though, in most areas whilst under the protection of the Convention for the Conservation of Antarctic Seals. A small population on Heard Island is endangered. Unlike the Antarctic fur seal, whose genetic variation is low due to hunting making all but one breeding colony extinct by 1900, the diversity amongst subantarctic specimens remains high. Subantarctic fur seals hunt in shallow waters at night, when myctophid fish come close to the surface, they feed on squid. Wynen, Louise P. et al. "Postsealing genetic variation and population structure of two species of fur seal". Molecular Ecology. Vol. 9.. Pp. 299–314. "Arctocephalus tropicalis". Integrated Taxonomic Information System. Retrieved 24 January 2006.
Randall R. Reeves. National Audubon Society Guide to Marine Mammals of the World. Alfred A. Knopf, Inc. ISBN 0375411410
The Indian Ocean is the third largest of the world's oceanic divisions, covering 70,560,000 km2. It is bounded by Asia on the north, on the west by Africa, on the east by Australia, on the south by the Southern Ocean or, depending on definition, by Antarctica; the Indian Ocean is named after India. Called the Sindhu Mahasagara or the great sea of the Sindhu by the Ancient Indians, this ocean has been variously called Hindu Ocean, Indic Ocean, etc. in various languages. The Indian Ocean was known earlier as the Eastern Ocean; the term was still in use during the mid-18th century. The borders of the Indian Ocean, as delineated by the International Hydrographic Organization in 1953 included the Southern Ocean but not the marginal seas along the northern rim, but in 2000 the IHO delimited the Southern Ocean separately, which removed waters south of 60°S from the Indian Ocean, but included the northern marginal seas. Meridionally, the Indian Ocean is delimited from the Atlantic Ocean by the 20° east meridian, running south from Cape Agulhas, from the Pacific Ocean by the meridian of 146°49'E, running south from the southernmost point of Tasmania.
The northernmost extent of the Indian Ocean is 30° north in the Persian Gulf. The Indian Ocean covers 70,560,000 km2, including the Red Sea and the Persian Gulf but excluding the Southern Ocean, or 19.5% of the world's oceans. The ocean's continental shelves are narrow. An exception is found off Australia's western coast; the average depth of the ocean is 3,890 m. Its deepest point is Sunda Trench at a depth of 7,450 m. North of 50° south latitude, 86% of the main basin is covered by pelagic sediments, of which more than half is globigerina ooze; the remaining 14% is layered with terrigenous sediments. Glacial outwash dominates the extreme southern latitudes; the major choke points include Bab el Mandeb, Strait of Hormuz, the Lombok Strait, the Strait of Malacca and the Palk Strait. Seas include the Gulf of Aden, Andaman Sea, Arabian Sea, Bay of Bengal, Great Australian Bight, Laccadive Sea, Gulf of Mannar, Mozambique Channel, Gulf of Oman, Persian Gulf, Red Sea and other tributary water bodies.
The Indian Ocean is artificially connected to the Mediterranean Sea through the Suez Canal, accessible via the Red Sea. All of the Indian Ocean is in the Eastern Hemisphere and the centre of the Eastern Hemisphere, the 90th meridian east, passes through the Ninety East Ridge. Marginal seas, gulfs and straits of the Indian Ocean include: Several features make the Indian Ocean unique, it constitutes the core of the large-scale Tropical Warm Pool which, when interacting with the atmosphere, affects the climate both regionally and globally. Asia prevents the ventilation of the Indian Ocean thermocline; that continent drives the Indian Ocean monsoon, the strongest on Earth, which causes large-scale seasonal variations in ocean currents, including the reversal of the Somali Current and Indian Monsoon Current. Because of the Indian Ocean Walker circulation there is no continuous equatorial easterlies. Upwelling occurs near the Horn of Africa and the Arabian Peninsula in the Northern Hemisphere and north of the trade winds in the Southern Hemisphere.
The Indonesian Throughflow is a unique Equatorial connection to the Pacific. The climate north of the equator is affected by a monsoon climate. Strong north-east winds blow from October until April. In the Arabian Sea the violent Monsoon brings rain to the Indian subcontinent. In the southern hemisphere, the winds are milder, but summer storms near Mauritius can be severe; when the monsoon winds change, cyclones sometimes strike the shores of the Arabian Sea and the Bay of Bengal. The Indian Ocean is the warmest ocean in the world. Long-term ocean temperature records show a rapid, continuous warming in the Indian Ocean, at about 0.7–1.2 °C during 1901–2012. Indian Ocean warming is the largest among the tropical oceans, about 3 times faster than the warming observed in the Pacific. Research indicates that human induced greenhouse warming, changes in the frequency and magnitude of El Niño events are a trigger to this strong warming in the Indian Ocean. South of the Equator the Indian Ocean is gaining heat from June to October, during the austral winter, while it is losing heat from November to March, during the austral summer.
Among the few large rivers flowing into the Indian Ocean are the Zambezi and Jubba in Africa. The ocean's currents are controlled by the monsoon. Two large gyres, one in the northern hemisphere flowing clockwise and one south of the equator moving anticlockwise, constitute the dominant flow pattern. During the winter monsoon, circulation is reversed north of 30°S and winds are weakened during winter and the transitional periods between the monsoons. Deep water circulation is controlled by inflows from the Atlantic Ocean, the Red Sea, Antarctic currents. North of 20 ° south latitude the minimum surface temperature is 22 °C. Southward of 40° south latitude, temperatures
French Southern and Antarctic Lands
The French Southern and Antarctic Lands is an overseas territory of France. It consists of: Kerguelen Islands, a group of volcanic islands in the southern Indian Ocean, southeast of Africa equidistant between Africa and Australia; the territory is sometimes referred to as the French Southern Lands or French Southern Territories to emphasize non-recognition of French sovereignty over Adélie Land as part of the Antarctic Treaty system. The territory has no permanent civilian population; those resident consist of visiting military personnel, scientific researchers and support staff. The French Southern and Antarctic Lands have formed a territoire d'outre-mer of France since 1955, they were administered from Paris by an administrateur supérieur assisted by a secretary-general. The territory is divided into five districts: a According to new law 2007-224 of February 21, 2007, the Scattered Islands constitute the TAAF's fifth district; the TAAF website does not mention their population. The data are not included in the totals.b.
The headquarters of the district chief lies beyond the TAAF, in Saint-Pierre on Réunion Island.c The Territory's principal station is Martin-de-Viviès on Île Amsterdam. The capital and headquarters of the Territorial administrator lies beyond the TAAF, in Saint-Pierre on Réunion Island; each district is headed by a district chief. Because there is no permanent population, there is no elected assembly, nor does the territory send representatives to the national parliament; the territory includes Amsterdam Island, Saint-Paul Island, Crozet Islands, the Kerguelen Islands in the southern Indian Ocean near 43°S, 67°E, along with Adélie Land, the sector of Antarctica claimed by France, named by the French explorer Jules Dumont d'Urville after his wife. Adélie Land and the islands, totaling 7,781 km2, have no indigenous inhabitants, though in 1997 there were about 100 researchers whose numbers varied from winter to summer. Amsterdam Island and Saint-Paul Island are extinct volcanoes and have been delineated as the Amsterdam and Saint-Paul Islands temperate grasslands ecoregion.
The highest point in the territory is Mont Ross on Kerguelen Island at 1,850 m. There are few airstrips on the islands, only existing on islands with weather stations, the 1,232 km of coastline have no ports or harbors, only offshore anchorages; the islands in the Indian Ocean are supplied by the special ship Marion Dufresne sailing out of Le Port in Réunion Island. Terre Adélie is supplied by Astrolabe sailing out of Hobart in Tasmania. However, the territory has a merchant marine fleet totaling 2,892,911 GRT/5,165,713 tonnes deadweight, including seven bulk carriers, five cargo ships, ten chemical tankers, nine container ships, six liquefied gas carriers, 24 petroleum tankers, one refrigerated cargo ship, ten roll-on-roll-off carriers; this fleet is maintained as a subset of the French register that allows French-owned ships to operate under more liberal taxation and manning regulations than permissible under the main French register. This register, however, is to vanish; the territory's natural resources are limited to fish and crustaceans.
Economic activity is limited to servicing meteorological and geophysical research stations and French and other fishing fleets. The main fish resources are Patagonian spiny lobster. Both are poached by foreign fleets; such arrests can result in heavy fines and/or the seizure of the ship. France sold licenses to foreign fisheries to fish the Patagonian toothfish; the territory takes in revenues of about €16 million a year. The French Southern Territories have been given the following country codes: FS and TF. France Outline of France French overseas departments and territories Administrative divisions of France Islands controlled by France in the Indian and Pacific oceans French colonial empire List of French possessions and colonies Wikimedia Atlas of the French Southern and Antarctic Lands Official website French Southern and Antarctic Lands – Official French website "French Southern and Antarctic Lands"; the World Factbook. Central Intelligence Agency. French Southern Territories at Curlie Southern & Antarctic Territories Crozet Archipelago Kerguelen Archipelago Terre Adélie
Indian yellow-nosed albatross
The Indian yellow-nosed albatross is a member of the albatross family, is the smallest of the mollymawks. In 2004, BirdLife International split this species from the Atlantic yellow-nosed albatross. Mollymawks are a type of albatross that belong to the family Diomedeidae of the order Procellariiformes, along with shearwaters, storm petrels, diving petrels, they share certain identifying features. They have nasal passages called naricorns attached to the upper bill; the bills of Procellariiformes are unique in that they are split into between 9 horny plates. They make a stomach oil made of wax esters and triglycerides, stored in the proventriculus; this is used against predators and as an energy rich food source for chicks and for the adults during their long flights. They have a salt gland above the nasal passage, it helps desalinate their bodies, due to the high amount of ocean water. The type-specimen is a black-beaked juvenile, which has caused confusion over its status until recently; the Indian yellow-nosed albatross is 76 cm long and is 2 m across the wings.
The adult has a pale grey or white head and nape, with a dark grey mantle and tail. Its rump and underparts are white, its underwing is white with a black tip with a narrow black margin at the leading edge, its bill is black with a red tip. The juvenile has all black bill, it is difficult to distinguish from the related grey-headed albatross and Atlantic yellow-nosed albatross, the latter with which it was long considered conspecific and is still considered by some a subspecies of. It can be distinguished from the Atlantic yellow-nosed by its head, the grey plumage of, lighter on the Indian yellow-nosed. Like all albatrosses, the Indian yellow-nosed albatross is a colonial breeder, it breeds annually, the adults begin breeding at the age of eight years. A mud nest is built in bare rocky areas or in tussock grass or ferns, a single egg is laid; the nesting season begins with laying occurring around September/October. Incubation lasts around 70 days. After hatching the chick takes around 115 days to fledge.
It feeds on fish and cephalopods. It breeds on Prince Edward Islands, the Crozet Islands, Kerguelen Island, Amsterdam Island and St Paul Islands in the Indian Ocean; when feeding during incubation, birds will forage up to 1,500 km from the colony. At sea it ranges from South Africa to the Pacific Ocean just beyond New Zealand, ranging from 30° S to 50° S, it is considered to be an endangered species by the IUCN, due to dramatic declines in the last seventy years, caused by interactions with longline fisheries and the outbreak of introduced diseases, such as avian cholera and Erysipelothrix rhusiopathiae. It has an occurrence range of 35,300,000 km2 and a breeding range of 1,400 km2. A 2004 population estimate established; this is based on earlier counts as follows: 27,000 breeding pairs breed on Amsterdam Island, 7,500 pair on Prince Edward Island, 7,030 on Crozet Island, 50 on Kerguelen Island, 3 pair on St. Paul Island for a total of 41,580 pair or 83,000 mature individuals. Take into account decreasing trends for the stated number.
Monitoring of the birds and studying of its foraging is an ongoing project on Amsterdam Island, Prince Edward Islands is a nature preserve. A vaccination remains untested. In 2006, the Indian Ocean Tuna Commission adopted a measure to require longline boats to use a bird streamer south of 30°S, South Africa requires its boats to use a variety of mitigation processes. ACAP. "ACAP species assessments, Indian Yellow-nosed albatross". ACAP. BirdLife International. "Indian Yellow-nosed Albatross Thalassarche carteri - BirdLife Species Factsheet". Data Zone. Retrieved 18 Feb 2009. BirdLife International. "The BirdLife checklist of the birds of the world, with conservation status and taxonomic sources". Retrieved 18 Feb 2009. Brooke, M.. "Procellariidae". Albatrosses And Petrels Across The World. Oxford, UK: Oxford University Press. ISBN 0-19-850125-0. Cherel, Y.. "A review of the food of albatrosses". In Robertson, G.. Chipping Norton, Australia: Surrey Beatty & Sons. Pp. 113–136. Clements, James; the Clements Checklist of the Birds of the World.
Ithaca, NY: Cornell University Press. ISBN 978-0-8014-4501-9. Double, M. C.. "Procellariiformes". In Hutchins, Michael. Grzimek's Animal Life Encyclopedia. 8. Birds I Tinamous and Ratites to Hoatzins. Joseph E. Trumpey, Chief Scientific Illustrator. Farmington Hills, MI: Gale Group. Pp. 107–111. ISBN 0-7876-5784-0. Ehrlich, Paul R.. The Birders Handbook. New York, NY: Simon & Schuster. Pp. 29–31. ISBN 0-671-65989-8. Harrison, P.. Seabirds: an identification guide. Beckenham, U. K.: Croom Helm. Pinaud, D.. "At-sea distribution and scale-dependent foraging behaviour of petrels and albatrosses: a comparative study". Journal of Animal Ecology. 76: 9–19. Doi:10.1111/j.1365-2656.2006.01186.x. Remsen Jr. J. V.. "A classification of the bird species of South America, South American Classification Committee, American Ornithologists' Union". South American Classification Committee. American Ornithologists' Union. Archived from the original on 2009-03-02. Retrie
Wilson's storm petrel
Wilson's storm petrel known as Wilson's petrel, is a small seabird of the austral storm petrel family Oceanitidae. It is one of the most abundant bird species in the world and has a circumpolar distribution in the seas of the southern hemisphere but extending northwards during the summer of the northern hemisphere; the world population has been estimated to be more than 50 million pairs. The name commemorates the Scottish-American ornithologist Alexander Wilson; the genus name Oceanites refers to the three thousand daughters of Tethys. The species name is from Latin oceanus, "ocean". Described in the genus Procellaria it has been placed under the genus Oceanites. Two or three subspecies are recognized and one population maorianus from New Zealand may be extinct; the nominate population breeds from Cape Horn to the Kerguelen Islands while exasperatus breeds along the Antarctic coast in the South Shetland and other islands. The population from Tierra del Fuego was described as chilensis but this is considered a nomen nudum although some authors have reinstated it, noting that it can be distinguished by white mottling on the belly.
The name Mother Carey's chicken was used in early literature and applied to several petrel species while the generic name of stormy petrel referred to the idea that their appearance foretold stormy weather. F. M. Littler and others called it the yellow-webbed storm-petrel. Wilson's storm petrel is 16 -- 18.5 cm in length with a 38 -- 42 cm wingspan. It is larger than the European storm petrel and is dark brown in all plumages, except for the white rump and flanks; the feet jut beyond the square ended tail in flight. The European storm petrel has a distinct whitish lining to the underwing and a nearly all dark upperwing. Wilson's storm petrel has a diffuse pale band along the upper wing coverts and lacks the distinctive white underwing lining; the webbing between the toes is yellow with black spots in pre-breeding age individuals. This species breeds on the Antarctic coastlines and nearby islands such as the South Shetland Islands during the summer of the southern hemisphere, it spends the rest of the year at sea, moves into the northern oceans in the southern hemisphere's winter.
It is much more common in the north Atlantic than the Pacific. Wilson's storm petrel is common off eastern North America in the northern summer and the seasonal abundance of this bird in suitable European waters has been revealed through pelagic boat trips, most notably in the area of the Isles of Scilly and Great Britain, it is pelagic outside the breeding season, this, together with its remote breeding sites, makes Wilson's petrel a difficult bird to see from land. Only in severe storms might this species be pushed into headlands. Wilson's storm petrel has a more direct gliding flight than other small petrels, like most others it flies low over the seas surface and has the habit of pattering on the water surface as it picks planktonic food items from the ocean surface, their unique fluttering and hovering flight is achieved with their wings held high. In calm weather, they can make use of the slight breeze produced by the waves and in effect soar while using their feet to stabilize themselves.
Like the European storm petrel, it is gregarious, will follow ships and fishing boats. A soft peeping noise is heard while the birds are feeding, they feed predominantly on planktonic invertebrates close to the surface plunging below the surface to capture prey. They may however sometimes take 3–8 cm long fish in the family Myctophidae. At 40 g on average, it is the smallest warm-blooded animal, it nests in colonies close to the sea in rock crevices or small burrows in soft earth and lays a single white egg. Like most petrels, its walking ability is limited to a short shuffle to the burrow. In the Antarctic, nests may sometimes get snowed over leading to destruction of chicks; this storm petrel is nocturnal at the breeding sites to avoid predation by larger gulls and skuas, will avoid coming to land on clear moonlit nights. Both parents feed the single chick; the chicks beg for food, more vigorously when hungry. Chicks remain at nest for about 60 days and are fed on krill and amphipods. Adults have the ability to identify their nest burrows in the dark and their mates by olfactory cues.
Widespread throughout its large range, Wilson's storm petrel is evaluated as least concern on the IUCN Red List of Threatened Species. Harrison, Peter. Seabirds of the World. Princeton: Princeton University Press. ISBN 0-691-01551-1. Bull, John; the Audubon Society Field Guide to North American Birds, Eastern Region. New York: Alfred A. Knopf. ISBN 0-394-41405-5. Beck, J. R. & Brown, D. W. 1972. The Biology of Wilson's Storm Petrel, Oceanites oceanicus at South Orkney Islands. British Antarctic Survey Scientific Reports No. 69. Bourne, W. R. P. 1983. Letters. British Birds 76: 316-317. Bourne, W. R. P. 1987. Parallel variation in the markings of Wilson's and Leach's Storm-petrels. Sea Swallow 36: 64. Bourne, W. R. P. 1988. Letters. British Birds 81: 402-403. British Ornithologists’ Union 2008. British Ornithologists’ Union Records Committee: 36th Report. Ibis 150: 218-220. Copestake, P. G. & Croxall, J. P. 1985. Aspects of the breeding biology of Wilson's Storm Petrel Oceanites oceanicus at Bird Island, South Georgia. British Antarctic Survey Bulletin 66: 7-17.
Croxall, J. P. et al. 1988. Food and feeding ecology of Wilson's storm petrel Oceanites oce
The Australasian gannet known as Australian gannet and tākapu, is a large seabird of the booby and gannet family, Sulidae. Adults are white, with black flight feathers at the wingtips and lining the trailing edge of the wing; the central tail feathers are black. The head is tinged buff-yellow, with a pale blue-grey bill edged in black, blue-rimmed eyes. Young birds have mottled dark above and light below; the head is an intermediate mottled grey, with a dark bill. The birds acquire more white in subsequent seasons until they reach maturity after five years; the species range over water above the continental shelf along the southern and eastern Australian coastline, from Steep Point in Western Australia to Rockhampton, Queensland, as well as the North and South Islands of New Zealand, Lord Howe and Norfolk Islands. Nesting takes place in colonies along the coastlines of New Zealand and Tasmania—mostly on offshore islands, although there are several mainland colonies in both countries. Territorial when breeding, the Australasian gannet performs agonistic displays to defend its nest.
Potential and mated pairs engage in greeting displays. The nest is a cup-shaped mound composed of seaweed and other debris, built by the female from material gathered by the male. A single pale blue egg is laid yearly; the chick is soon covered in white down. Fed regurgitated fish by its parents, it grows and outweighs the average adult when it fledges; these birds are spectacular fishers, plunging into the ocean at high speed. They eat squid and forage fish that school near the surface; the species faces few natural or man-made threats, since its population is growing it is considered to be a least-concern species by the International Union for Conservation of Nature. Sir Joseph Banks shot three Australasian gannets in New Zealand waters on 24 December 1769 off Three Kings Islands; the birds were cooked in a goose pie, enjoyed by the sailors, for Christmas the next day. Daniel Solander wrote a formal description, noting its differences from the familiar northern gannet giving it the name Pelecanus chrysocephalus before crossing it out and changing it to Pelecanus sectator.
Sydney Parkinson illustrated the bird as P. sectator, misread as P. serrator by authorities. The species name has been translated as "sawyer", from serra "saw", linked to the serrated bill. John Gould described specimens from the Derwent River and Actaeon Island in Tasmania as Sula australis in 1841; the binomial name Sula australis had been used by J. F. Stephens for the red-footed booby. English zoologist George Robert Gray wrote of the species in 1843 using Gould's name but soon switching to Sula serrator, based on Parkinson's drawing. Although Gould stuck with S. australis, S. serrator became the preferred term over time."Australasian gannet" has been designated as the official common name for the species by the International Ornithologists' Union. It is known as Pacific gannet and, in Australia, as Australian gannet, booby, or solan goose. In New Zealand it is known by the Māori name tākapu or tākupu, a word of wider Polynesian origin for a gannet or booby; the Sulidae, the gannets and boobies, appeared about 30 million years ago.
Early Sulidae fossils most resembled the boobies, although they were more aquatic, the gannets splitting off about 16 million years ago. The gannets evolved in the northern hemisphere colonising the southern oceans; the most ancient extant species may be the Abbott's booby the sole survivor of an otherwise extinct separate lineage. A 2011 genetic study of nuclear and mitochondrial DNA suggests that the ancestor of the gannets arose around 2.5 million years ago before splitting into northern and southern lineages. The latter split into the Cape and Australasian gannets around 0.5 million years ago. The three gannets are considered to be separate species forming a superspecies, though they have formerly been classified as subspecies of the northern gannet. An adult Australasian gannet is 84–91 cm long, weighs 2.3 kg, has a 170–200 cm wingspan. The two sexes are 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 had a larger ulna and smaller bill. The plumage is white with black flight feathers on the wings, central retrices of the tail; some individuals have more extensive black plumage of their tail feathers. There is a sharp demarcation between dark plumage. Black primary feathers are more resilient to wear; the head and hindneck are tinged buff-yellow. The colour is more pronounced during breeding season; the eyes have a light grey iris surrounded by a pale blue eye ring, bare black skin on the face which merges into the bill. In adults, the bill is pearly grey with dark grey or black edges, 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, dark grey legs and feet. Australasian gannets take 2–5 years to gain adult plumage.
Over this period, the upperparts and underparts whiten and the crown and nape become buff-coloured, but there is great variation