The grey-headed albatross (Thalassarche chrysostoma) also known as the grey-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-grey 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. 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.
The name chrysostoma is derived from two Greek words. Khrusos means "gold" and stoma means "the mouth", in reference to its golden bill.
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). 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.
Range and habitat
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. Birds that roost in the Marion Island area forage for food in the sub-tropical zone. Juveniles or non-breeding adults fly freely throughout all the southern oceans, north to 35°S.
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. 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, 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. If a pair has managed to successfully raise a chick it will not breed in the following year, taking the year off. 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 vulnerable due to rapidly declining numbers. 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), with a population, estimated in 2004, of 250,000. Estimates place 48,000 pairs at South Georgia Island, 6,200 on Marion Island, 3,000 pairs on Prince Edward Islands, 7,800 pairs on Campbell Island, 16,408 pairs in Chile, 84 pairs on Macquarie Island, 5,940 on Crozet Island, and 7,905 on Kerguelen Islands
Populations have been shrinking based on different studies. Bird Island numbers have been reduced 20% to 30% in the last 30 years. Marion Island registered 1.75% reduction per year until 1992 and now appears to be stable. Campbell Island has seen reduction of 79% to 87% since the 1940s. Overall, the trends looks like a 30-40% reduction over 90 years (3 generations). 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. Longline fishing is responsible for other deaths.
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 and Macquarie Island are World Heritage Sites.
- ^ a b BirdLife International (2013). "Thalassarche chrysostoma". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
- ^ Brands, S. (2008)
- ^ Double, M. C. (2003)
- ^ Ehrlich, Paul R. (1988)
- ^ Gotch, A. F. (1995)
- ^ Brooke, Michael, Albatrosses and Petrels across the World (Bird Families of the World). Oxford University Press (2004), ISBN 978-0-19-850125-1
- ^ a b c d e f g BirdLife International (2008)
- ^ Prince, et al. (1998)
- ^ Phillips, et al. (2004)
- ^ Nel, et al. (2001)
- ^ Clements, James (2007)
- ^ Prince (1980)
- ^ Cherel, et al. (2002)
- ^ Xavier, et al. (2003)
- ^ Arata, et al. (2004)
- ^ Croxall & Gales (1998)
- ^ Brooke, (2004)
- ^ Poncet, et al. (2006)
- ^ Crawford, et al. (2003)
- ^ Ryan, et al. (2003)
- ^ Moore (2004)
- ^ Arata & Morena (2002)
- ^ a b Gales (1998)
- ^ Croxall et al. (1998)
- ^ Nel et al. (2002)
- ^ Taylor, (2000)
- ^ CCAMLR (1997)
- ^ CCAMLR (1998)
- ^ Nel et al. (2002a)
- Arata, J.; Moreno, C. A. (2002). "Progress report of Chilean research on albatross ecology and conservation". Convention for the Conservation of Antarctic Marine Living Resources Working Group on Fish Stock Assessment.
- Arata, J.; Robertson, G.; Valencia, J.; Xavier, J. C.; Moreno, C. A. (2004). "Diet of Grey-headed Albatrosses at Diego Ramirez Islands, Chile: ecological implications". Antarctic Science 16: 263–275.
- BirdLife International (2008). "Grey-headed Albatross - BirdLife Species Factsheet". Data Zone. Retrieved 22 Feb 2009.
- Brands, Sheila (14 Aug 2008). "Systema Naturae 2000 / Classification - Diomedea subg. Thalassogeron -". Project: The Taxonomicon. Retrieved 22 Feb 2009.
- Brooke, M. (2004). "Procellariidae". Albatrosses And Petrels Across The World. Oxford, UK: Oxford University Press. ISBN 0-19-850125-0.
- CCAMLR (1998). Report of the XVII meeting of the Scientific Committee. Hobart (Hobart, Australia: Committee for the Conservation of Antarctic Marine Living Resources).
- CCAMLR (1997). Report of the XVI meeting of the Scientific Committee. Hobart (Hobart, Australia: Committee for the Conservation of Antarctic Marine Living Resources).
- Cherel, Y.; Weimerskirch, H.; Trouve, C. (2002). "Dietary evidence for spatial foraging segregation in sympatric albatrosses (Diomedea spp.) rearing chicks at Iles Nuageuses, Kerguelen". Marine Biology 141: 1117–1129. doi:10.1007/s00227-002-0907-5.
- Clements, James (2007). The Clements Checklist of the Birds of the World (6 ed.). Ithaca, NY: Cornell University Press. ISBN 978-0-8014-4501-9.
- Crawford, R. J. M.; Cooper, J.; Dyer, B. M.; Greyling, M.; Klages, N. T. W.; Ryan, P. G.; Petersen, S.; Underhill, L. G.; Upfold, L.; others (2003). "Populations of surface nesting seabirds at Marion Island, 1994/95-2002/03". African Journal of Marine Science 25: 427–440. doi:10.2989/18142320309504032.
- Croxall, J. P.; Gales, R. (1998). "Assessment of the conservation status of albatrosses". In Robertson, G.; Gales, R. Albatross biology and conservation. Chipping Norton, Australia: Surrey Beatty & Sons.
- Croxall, J. P.; Prince, P. A.; Rothery, P.; Wood, A. G. (1998). "Population changes in albatrosses at South Georgia". In Robertson, G.; Gales, R. Albatross biology and conservation. Chipping Norton, Australia: Surrey Beatty & Sons. pp. 69–83.
- Croxall, J. P.; Silk, J.R.D.; Phillips, R.A.; Afanasyev, V.; Briggs, D.R. (2005). "Global Circumnavigations: Tracking year-round ranges of nonbreeding Albatrosses". Science 307: 249–250. doi:10.1126/science.1106042. PMID 15653503.
- del Hoyo, Josep, Elliott, Andrew & Sargatal, Jordi (1992). Handbook of Birds of the World Vol 1. Barcelona:Lynx Edicions, ISBN 84-87334-10-5
- Double, M. C. (2003). "Procellariiformes (Tubenosed Seabirds)". In Hutchins, Michael; Jackson, Jerome A.; Bock, Walter J. et al. Grzimek's Animal Life Encyclopedia. 8. Birds I Tinamous and Ratites to Hoatzins. Joseph E. Trumpey, Chief Scientific Illustrator (2 ed.). Farmington Hills, MI: Gale Group. pp. 107–111. ISBN 0-7876-5784-0.
- Ehrlich, Paul R.; Dobkin, David, S.; Wheye, Darryl (1988). The Birders Handbook (First ed.). New York, NY: Simon & Schuster. pp. 29–31. ISBN 0-671-65989-8.
- Gales, R. (1998). "Albatross populations: status and threats". In Robertson, G.; Gales, R. Albatross biology and conservation. Chipping Norton, Australia: Surrey Beatty & Sons.
- Gotch, A. F. (1995) . "Albatrosses, Fulmars, Shearwaters, and Petrels". Latin Names Explained A Guide to the Scientific Classifications of Reptiles, Birds & Mammals. New York, NY: Facts on File. p. 191. ISBN 0-8160-3377-3.
- Moore, P. J. (2004). "Abundance and population trends of mollymawks on Campbell Island". Science for Conservation (Wellington, NZ: Department of Conservation) 242.
- Nel, D. C.; Lutjeharms, J. R. E.; Pakhomov, E. A.; Ansorge, I. J.; Ryan, P. G.; Klages, N. T. W. (2001). "Exploitation of mesoscale oceanographic features by Grey-headed Albatross Thalassarche chrysostoma in the southern Indian Ocean". Marine Ecology Progress Series 217: 15–26. doi:10.3354/meps217015.
- Nel, D. C.; Ryan, P. G.; Crawford, R. J. M.; Cooper, J.; Huyser, O. (2002). "Population trends of albatrosses and petrels at sub-Antarctic Marion Island". Polar Biology (25): 81–89.
- Nel, D. C.; Ryan, P. G.; Watkins, B. P. (2002a). "Seabird mortality in the Patagonian Toothfish longline fishery around the Prince Edward Islands". Antarctic Science 14: 151–161. doi:10.1017/s0954102002000718.
- Phillips, R. A.; Silk, J. R. D.; Phalan, B.; Catry, P.; Croxall, J. P. (2004). "Seasonal sexual segregation of two Thalassarche albatross species: competitive exclusion, reproductive role specialization or foraging niche divergence?". Proceedings of the Royal Society B 271: 1283–1291. doi:10.1098/rspb.2004.2718.
- Poncet, S.; Robertson, G.; Phillips, R. A.; Lawton, K.; Phalan, B.; Trathan, P. N.; Croxall, J. P. (2006). "Status and distribution of wandering Black-browed and Grey-headed Albatrosses breeding at South Georgia". Polar Biology 29: 772–781. doi:10.1007/s00300-006-0114-9.
- Prince, P. A. (1980). "The food and feeding ecology of Grey-headed Albatross Diomedea chrysostoma and Black-rowed Albatross D. melanophris". Ibis 122: 476–488. doi:10.1111/j.1474-919x.1980.tb00902.x.
- Prince, P. A.; Croxall, J. P.; Trathan, P. N.; Wood, A. G. (1998). "The pelagic distribtuion of South Georgia albatrosses and their relationships with fisheries". In Robertson, G.; Gales, R. Albatross biology and conservation. Chipping Norton, Australia: Surrey Beatty & Sons.
- Ryan, P. G.; Cooper, J.; Dyer, B. M.; Underhill, L. G.; Crawford, R. J. M.; Bester, M. N. (2003). "Counts of surface-nesting seabirds breeding at Prince Edward Islands, Summer 2001/02". African Journal of Marine Science 25: 441–451. doi:10.2989/18142320309504033.
- Taylor, G. A. (2000). "Action plan for seabird conservation in New Zealand. Wellington: Department of Conservation". Threatened Species Occasional Publication 16.
- Xavier, J. C.; Croxall, J. P.; Trathan, P. N.; Wood, A. G. (2003). "Feeding strategies and diets of breeding grey-headed and wandering albatrosses at South Georgia". Marine Biology 143: 221–232. doi:10.1007/s00227-003-1049-0.