The shy albatross (Thalassarche cauta, formerly Diomedea cauta), 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[update], 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.
Some authorities call this species the white-capped albatross, but that name is more commonly applied to Thalassarche cauta steadi.
Taxonomy
This
mollymawk was once considered to be the same
species as the
Salvin's albatross, Thalassarche salvini, and the
Chatham albatross, Thalassarche eremita, but they were split around 2004. In 1998, Robertson and Nunn suggested a four-way split including the
white-capped albatross, Thalassarche steadi.[3] The three-way split was accepted by Brooke in 2004,[4] the
ACAP in 2006,[5]SACC in 2008,[6][7][8] and
BirdLife International by 2000.[9]James Clements was the last major holdout on the three-way split[10] but later accepted it.[11] The fourth split, steadi, was only accepted by the ACAP in 2006,[5] and BirdLife International in 2008.[9] Finally, following Brooke, this species was shifted from Diomedea to Thalassarche, which was generally agreed upon by most experts.[citation needed]
Mollymawks belong to the albatross family,
Diomedeidae, which shares the order
Procellariiformes with
shearwaters,
fulmars,
storm petrels, and
diving petrels. Procellariiformes have certain identifying features. They have nasal passages that attach to the upper bill, called
naricorns (although the nostrils on the albatross are on the sides of the bill). The bills are also unique in that they are split into between seven and nine horny plates. 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.[13] They also have a
salt gland that is situated above the nasal passage and helps desalinate their bodies, required due to the high amount of ocean water that they imbibe. It excretes a high saline solution from their nose.[14]
Within Australia, the bird is still shown as Diomedea cauta, Diomedea cauta cauta, or Thalassarche cauta cauta in some legislation and databases.[15]
Description
The shy albatross averages 90 to 99 cm (35–39 in) in length, 220 to 256 cm (87–101 in) wingspan,[16] and 4.1 kg (9.0 lb) in weight. Alongside its similarly sized sister species, the
Salvin's albatross, this species is considered the largest of the mollymawks or the small albatrosses.[17][18] It is a black, white and slate-grey bird with the characteristic black thumb mark at the base of the leading edge of the underwing. Adults have a white forehead and a crown, which is bordered on the bottom with a dark eyebrow and pale grey face. Its mantle, tail and upperwing are grey-black, and the rest is white. Its bill is grey-yellow with a prominent yellow
culmen and yellow tip.[19]
The shy albatross feeds by a combination surface-seizing and some pursuit diving – it has been recorded diving as deep as 5 m (16 ft). Fish,
cephalopods,
crustacea, and
tunicates are the sustenance for this species.[21]
Reproduction
The shy albatross breeds on rocky islands and builds mounded nests of soil, grass, and roots. They lay one egg in the second half of September.[4]
Flight endurance
Some shy albatross are able to fly 1,000 kilometres (620 mi) in 24 hours.[20]
Juvenile birds are known to fly as far as
South Africa;[26][27] otherwise, non-breeding birds can be found throughout the southern oceans, but specifics are hard to determine due to their similarity to the other species.[5][28] It is sometimes found off the
Pacific coast of the United States.
Conservation
The
IUCN classifies this species as
near threatened,[1] with an occurrence range of 23,900,000 km2 (9,200,000 sq mi). The population from an estimate in 2007 was 25,500 breeding birds with 5,100 pairs on
Albatross Island, 270 pairs on
Pedra Branca, and 7,380 on the
Mewstone.[19] Historically, they were exploited for their feathers, and by 1909 there were only 300 pairs left on Albatross Island.[4][29]
Today,
longline fishing still impacts this species but their numbers have been maintained despite this threat.[27] They also had an
avian pox outbreak on Albatross Island that has impacted their numbers slightly.[30] Finally, the
Australasian gannet, Morus serrator is the primary threat to their survival.[5]
In June 2020, the
Australian Government changed the status of the bird under the Environment Protection and Biodiversity Conservation Act 1999 from "Vulnerable" to "Endangered", with the bird facing the main threats from
climate change and
fisheries (as
bycatch victims, either caught in
trawling nets, or on hooks in the longline fishing industry), as well as disease and competition with other seabirds. The change in status is not considered to be due to poor management.[20] Listings under state and territory legislation were mostly still "vulnerable" at this time.[15]
The bird can only be monitored on Albatross Island, as the other two islands are inaccessible, but there are thought to be 15,000 pairs of shy albatross left.[20]
^Clements, J. F., T. S. Schulenberg, M. J. Iliff, D. Roberson, T. A. Fredericks, B. L. Sullivan, and C. L. Wood. 2016. The eBird/Clements checklist of birds of the world: v2016. Downloaded from
http://www.birds.cornell.edu/clementschecklist/download/
^
ab"Thalassarche cauta - Shy Albatross". Species Profile and Threats Database (SPRAT). Department of Agriculture, Water and the Environment, Australian Government. 28 June 2020. Retrieved 28 June 2020.
Baker, G. B.; Double, M. C.; Gales, R.; Tuck, G. N.; Abbott, C. L.; Ryan, P. G.; Petersen, S. L.; Robertson, C. J. R.; Alderman, R. (2007). "A global assessment of the impact of fisheries-related mortality on Shy and White-capped Albatrosses: conservation implications". Biological Conservation. 137 (3): 319–333.
doi:
10.1016/j.biocon.2007.02.012.
Brooke, M. (2004). "Procellariidae". Albatrosses And Petrels Across The World. Oxford, UK: Oxford University Press.
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Clements, James (2007). The Clements Checklist of the Birds of the World (6th ed.). Ithaca, NY: Cornell University Press.
ISBN978-0-8014-4501-9.
Double, M. C. (2003). "Procellariiformes (Tubenosed Seabirds)". In Hutchins, Michael; Jackson, Jerome A.; Bock, Walter J.; Olendorf, Donna (eds.). Grzimek's Animal Life Encyclopedia. Vol. 8 Birds I Tinamous and Ratites to Hoatzins. Joseph E. Trumpey, Chief Scientific Illustrator (2nd ed.). Farmington Hills, MI: Gale Group. pp. 107–111.
ISBN0-7876-5784-0.
Double, M. C.; Gales, R.; Reid, T.; Brothers, N.; Abbott, C. L. (2003). "Morphometric comparison of Australian shy and New Zealand white-capped albatrosses". Emu. 103 (4): 287–294.
doi:
10.1071/mu03012.
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Dunn, Jon L.; Alderfer, Jonathon (2006). "Albatrosses". In Levitt, Barbara (ed.). National Geographic Field Guide to the Birds of North America (fifth ed.). Washington D.C.: National Geographic Society. p. 80.
ISBN978-0-7922-5314-3.
Ehrlich, Paul R.; Dobkin, David, S.; Wheye, Darryl (1988). The Birders Handbook (First ed.). New York, NY: Simon & Schuster. pp. 29–31.
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Garnett, S. T.; Crowley, G. M. (2000). The action plan for Australian birds 2000. Canberra, Australia: Environment Australia.
Johnstone, G. W.; Dorwood, D. F. (1975). "The White-capped Albatross of Albatross Island: numbers and breeding behaviour". Emu. 75: 1–11.
doi:
10.1071/mu9750001.
Robertson, C. J. R.; Nunn, G. B. (1998). "Towards a new taxonomy for albatrosses". In Robertson, G.; Gales, R. (eds.). Albatross biology and conservation. Chipping Norton, Australia: Surrey Beatty & Sons. pp. 13–19.