Thegrey-headed albatross (Thalassarche chrysostoma) also known as thegray-headed mollymawk, is a largeseabird from thealbatrossfamily. It has acircumpolar distribution, nesting on isolated islands in theSouthern Ocean and feeding at high latitudes, further south than any of the othermollymawks. Its name derives from its ashy-gray head, throat and upper neck.
Mollymawks are a type of albatross that belong to the familyDiomedeidae from the orderProcellariiformes, along withshearwaters,fulmars,storm petrels, anddiving petrels. They share certain identifying features. First, they have nasal passages that attach to the upper bill callednaricorns, 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 astomach oil made up ofwax esters andtriglycerides that is stored in theproventriculus. 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 asalt 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 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. Itsbill 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]
At sea the grey-headed albatross is highlypelagic, more so than other mollymawks, feeding in the open oceans rather than over thecontinental shelves. They feed predominantly onsquid, taking also some fish,crustacea,carrion,cephalopods, andlampreys.[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 withtussock grass,[7] and incubated for 72 days. Studies at South Georgia'sBird 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 beforefledging, 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.
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 theIndian Ocean for thePatagonian 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]
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