Grey-headed albatross | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Aves |
Order: | Procellariiformes |
Family: | Diomedeidae |
Genus: | Thalassarche |
Species: | T. chrysostoma |
Binomial name | |
Thalassarche chrysostoma | |
Synonyms | |
Diomedea chrysostoma |
The grey-headed albatross (Thalassarche chrysostoma) also known as the gray-headed mollymawk, is a large seabird from the albatross family. It has a circumpolar distribution, nesting on isolated islands in the Southern Ocean and feeding at high latitudes, further south than any of the other mollymawks. Its name derives from its ashy-gray head, throat and upper neck.
Mollymawks are a type of albatross that belong to the family Diomedeidae from the order Procellariiformes, along with shearwaters, fulmars, storm petrels, and diving petrels. They share certain identifying features. First, they have nasal passages that attach to the upper bill called naricorns, although the nostrils of an albatross are on the sides of the bill. The bills of Procellariiformes are also unique in that they are split into between seven and nine horny plates. Finally, they produce a stomach oil made up of wax esters and triglycerides that is 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. [3] They also have a salt gland situated above the nasal passage that helps desalinate their bodies, to compensate for the ocean water they imbibe. It excretes a concentrated brine from the nostrils. [4]
The name chrysostoma is derived from two Greek words. Khrusos means "gold" and stoma means "the mouth", in reference to its golden bill. [5]
The grey-headed albatross averages 81 cm (32 in) in length and 2.2 m (7.2 ft) in wingspan. Weight can range from 2.8 to 4.4 kg (6.2 to 9.7 lb), with a mean mass of 3.65 kg (8.0 lb). [6] It has a dark ashy-grey head, throat, and upper neck, and its upper wings, mantle, and tail, are almost black. It has a white rump, underparts, and a white crescent behind its eyes. Its bill is black, with bright yellow upper and lower ridges, that shades to pink-orange at the tip. Its underwings are white with a lot of black on the leading edge and less on the trailing edge. Juveniles have a black bill and head and a darker nape. Its eye crescent is indistinct and its underwing is almost completely dark. [7]
Location | Population | Date | Trend |
---|---|---|---|
South Georgia Island | 48,000 pairs | 2006 | Declining |
Marion Island | 6,200 pairs | 2003 | Stable |
Prince Edward Islands | 3,000 pairs | 2003 | |
Campbell Island | 7,800 pair | 2004 | Declining |
Macquarie Island | 84 pairs | 1998 | |
Crozet Islands | 5,940 pairs | 1998 | |
Kerguelen Islands | 7,905 pairs | 1998 | |
Islas Diego Ramirez | 16,408 pairs | 2002 | |
Total | 250,000 | 2004 | Decreasing |
Grey-headed albatrosses nest in colonies on several islands in the Southern Ocean, with large colonies on South Georgia in the South Atlantic, and smaller colonies on Islas Diego Ramírez, Kerguelen Islands, Crozet Islands, Marion Island, and Prince Edward Islands in the Indian Ocean, Campbell Island and Macquarie Island south of New Zealand, and Chile. While breeding, they will forage for food within or south of the Antarctic Polar Frontal Zone. [8] [9] Birds that roost in the Marion Island area forage for food in the sub-tropical zone. [10] Juveniles or non-breeding adults fly freely throughout all the southern oceans, [7] north to 35°S. [11]
At sea the grey-headed albatross is highly pelagic, more so than other mollymawks, feeding in the open oceans rather than over the continental shelves. They feed predominantly on squid, taking also some fish, crustacea, carrion, cephalopods, and lampreys. [12] [13] [14] [15] Krill is less important as a food source for this species, reflecting their more pelagic feeding range. They are capable of diving as deep as 7 m (23 ft) to chase prey, but do not do so frequently.
A single egg is laid in a large nest, typically built on steep slopes or cliffs with tussock grass, [7] and incubated for 72 days. Studies at South Georgia's Bird Island have shown that the growing chick is fed 616 g (21.7 oz) of food every 1.2 days, with the chick increasing in weight to around 4,900 g (170 oz). Chicks then tend to lose weight before fledging, which happens after 141 days. Chick will generally not return to the colony for 6–7 years after fledging, and will not breed for the first time until several years after that.[ citation needed ] If a pair has managed to successfully raise a chick it will not breed in the following year, taking the year off. [7] During this time spent away from the colony they can cover great distances, often circling the globe several times.
The IUCN classifies this bird as endangered due to rapidly declining numbers in South Georgia which holds around half the world's population. [1] It has an occurrence range of 79,000,000 km2 (31,000,000 sq mi) and a breeding range of 1,800 km2 (690 sq mi), [7] with a population, estimated in 2004, of 250,000. [16] [17] Estimates place 48,000 pairs at South Georgia Island, [18] 6,200 on Marion Island, [19] 3,000 pairs on Prince Edward Islands, [20] 7,800 pairs on Campbell Island, [21] 16,408 pairs in Chile, [22] 84 pairs on Macquarie Island, 5,940 on Crozet Island, and 7,905 on Kerguelen Islands [23]
Populations have been shrinking based on different studies. Bird Island numbers have been reduced 20% to 30% in the last 30 years. [24] Marion Island registered 1.75% reduction per year until 1992 and now appears to be stable. [25] Campbell Island has seen reduction of 79% to 87% since the 1940s. [26] Overall, the trends looks like a 30-40% reduction over 90 years (3 generations). [7] Illegal or unregulated fishing in the Indian Ocean for the Patagonian toothfish, Dissostichus eleginoides resulted in 10–20,000 dead albatrosses, mainly this species, in 1997 and 1998. [27] [28] [29] Longline fishing is responsible for other deaths. [23] [30]
To assist this species, studies are being undertaken at most of the islands. Also, Prince Edward Islands is a special nature preserve, and Campbell Island [31] and Macquarie Island [32] are World Heritage Sites.
Seabirds are birds that are adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations. The first seabirds evolved in the Cretaceous period, and modern seabird families emerged in the Paleogene.
The snowy albatross, also known as the white-winged albatross, wandering albatross, or goonie, is a large seabird from the family Diomedeidae; they have a circumpolar range in the Southern Ocean. It is the most recently described species of albatross and was long considered to be the same species as the Tristan albatross and the Antipodean albatross. Together with the Amsterdam albatross, it forms the wandering albatross species complex. When the complex was split into four species, the English name of the nominate form was changed from wandering albatross to snowy albatross.
The black-browed albatross, also known as the black-browed mollymawk, is a large seabird of the albatross family Diomedeidae; it is the most widespread and common member of its family.
The family Procellariidae is a group of seabirds that comprises the fulmarine petrels, the gadfly petrels, the diving petrels, the prions, and the shearwaters. This family is part of the bird order Procellariiformes, which also includes the albatrosses and the storm petrels.
The Chatham albatross, also known as the Chatham mollymawk or Chatham Island mollymawk, is a medium-sized black-and-white albatross which breeds only on The Pyramid, a large rock stack in the Chatham Islands, New Zealand (Aotearoa). It is sometimes treated as a subspecies of the shy albatross Thalassarche cauta. It is the smallest of the shy albatross group.
The mollymawks are a group of medium-sized albatrosses that form the genus Thalassarche. The name has sometimes been used for the genus Phoebetria as well, but these are usually called sooty albatrosses. They are restricted to the Southern Hemisphere, where they are the most common of the albatrosses. They were long considered to be in the same genus as the great albatrosses, Diomedea, but a study of their mitochondrial DNA showed that they are a monophyletic taxon related to the sooty albatrosses, and they were placed in their own genus.
Salvin's albatross or Salvin's mollymawk, is a large seabird that breeds mainly on the Bounty Islands of New Zealand, with scant amounts on islands across the Southern Ocean. A medium-sized mollymawk, it was long considered to be a subspecies of the shy albatross.
The sooty albatross, also known to sailors as the Quaker, is a species of marine bird belonging to the albatross family Diomedeidae. It is a medium-sized albatross that sports a sooty-brown or sooty-black color. It can be found in the southern Atlantic Ocean, the southern Indian Ocean, and the Southern Ocean. This bird scavenges for squid, fish, and carrion. Like other albatrosses, these birds mate for life and return to the same breeding spots every season. A single pair will mate every other year on a variety of islands in the southern Atlantic Ocean and the southern Indian Ocean islands. This bird is an endangered species and conservation efforts are taking place.
The shy albatross, also known as shy mollymawk, is a medium-sized albatross that breeds on three remote islands off the coast of Tasmania, Australia, in the southern Indian Ocean. Its lifespan is about 60 years, and it has been seen as far afield as South Africa and the Pacific coast of the United States. As of June 2020, the species is listed as "Endangered" in Australia; there are thought to be 15,000 pairs of shy albatross left. It is Australia's only endemic albatross.
The white-capped albatross is a mollymawk that breeds on the islands off of New Zealand. Not all experts agree that this form should be recognized as a separate species from the shy albatross, Thalassarche cauta. It is a medium-sized black, slate gray, and white albatross and is the largest of the mollymawks.
Buller's albatross or Buller's mollymawk, is a small mollymawk in the albatross family.
The Campbell albatross or Campbell mollymawk, is a medium-sized mollymawk in the albatross family. It breeds only on Campbell Island and the associated islet of Jeanette Marie, in a small New Zealand island group in the South Pacific. It is sometimes considered a subspecies of the black-browed albatross. It is a medium-sized black and white albatross with a pale yellow iris.
The Indian yellow-nosed albatross is a member of the albatross family, and is the smallest of the mollymawks. In 2004, BirdLife International split this species from the Atlantic yellow-nosed albatross; however Clements has not split it yet, and the SACC has not either, but recognises the need for a proposal.
The Atlantic yellow-nosed albatross is a large seabird in the albatross family Diomedeidae.
Albatrosses, of the biological family Diomedeidae, are large seabirds related to the procellariids, storm petrels, and diving petrels in the order Procellariiformes. They range widely in the Southern Ocean and the North Pacific. They are absent from the North Atlantic, although fossil remains of short-tailed albatross show they once lived there up to the Pleistocene, and occasional vagrants are found. Great albatrosses are among the largest of flying birds, with wingspans reaching up to 2.5–3.5 metres (8.2–11.5 ft) and bodies over 1 metre (3.3 ft) in length. The albatrosses are usually regarded as falling into four genera, but disagreement exists over the number of species.
The white-chinned petrel also known as the Cape hen and shoemaker, is a large shearwater in the family Procellariidae. It ranges around the Southern Ocean as far north as southern Australia, Peru and Namibia, and breeds colonially on scattered islands. The white-chinned petrel was formerly considered to be conspecific with the spectacled petrel.
The Southern Indian Ocean Islands tundra is a tundra ecoregion that includes several subantarctic islands in the southern Indian Ocean.
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