|Diomedea||dabbenena||AO||Tristan da Cuhna group|
Albatrosses are the ‘largest’ birds in terms of wingspan. Royal Abatrosses, for instance, may reach a wing span of almost 3.5m, which make them look like feathered sail plaines. They are also the largest members of the tubenose family. Only the smallest albatross species are equalled in size by the Giant Petrels (Macronectes). Albatrosses occur in all oceans, except the northern part of the Atlantic. In ancient times they were also present in that part of the world, but nowadays only an occasional straggler find its way to the North Atlantic. Most of the 24 species are Southern Hemisphere breeders, only three actually breed north of the Equator in the Pacific Ocean.
Albatross taxonomy is subject of discussion for a long time, and has been at times rather chaotic. Based on external characters: plumage patterns, tail shapes, bill structure (size, organization of the plates and coloration) albatrosses were, until recently, divided in 13-14 species in four ‘natural groups’: the Great Albatrosses, the Mollymawks, the North Pacific Albatrosses, grouped in the genus Diomedea and the Sooty Albatrosses Phoebastria. More recently DNA-analyses supports the division in four distinct groups but the were elevated to a generic status and has led to a splitting into 24 species: Great Albatrosses Diomedea (7 species), the Northern (Pacific) Albatrosses Phoebastria (4 species), the southern Mollymawks Thalassarche (11 species) and the Sooty Albatrosses Phoebetria (2 species). Recently this taxonomy is challenged by who proposed to lump some of the ‘species’ again based on their molecular analysis. Since then the discussion flared up and has not ended yet. Some list six species of Great Albatrosses, including two subspecies of Antipodian Albatross.
|wingspan min.:||340||cm||wingspan max.:||360||cm|
|size min.:||105||cm||size max.:||115||cm|
|incubation min.:||0||days||incubation max.:||0||days|
|fledging min.:||0||days||fledging max.:||0||days|
Video Tristan Albatross
copyright: Youtube a grim video
On Inaccessible Island, its decline was probably due to predation by feral pigs (now absent) and humans. The failure to recover is unclear, but may be because young birds become entangled in thick vegetation. On Tristan, its extirpation was probably the result of human exploitation, although predation by rats may have been a factor. On Gough, predation by the introduced house mouse Mus musculus causes very low breeding success and alone is sufficient to drive a population decline of over 50% over three generations. An additional threat on Gough is peat slips caused by storms burying and killing nestlings and adults, though this is probably a very rare event. The main threat comes from interactions with longline fisheries, with a high proportion of “Wandering” Albatross bycatch in southern Brazilian waters being of this species, including a few birds banded at Gough. Satellite tracking of breeding birds indicates considerable overlap between birds and areas of longline fishing, although due to lag times associated with albatross demography we are probably only now likely to start to pick up population trends associated with longline mortality. Together, the dual threats of mice and bycatch give a worst-case scenario of extinction in roughly 30 years, though the true situation is likely a continued and severe decline. Having a distribution on relatively low-lying islands, this species is also potentially susceptible to climate change through sea-level rise and shifts in suitable climatic conditions.