White-capped albatross
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White-capped albatross ( Thalassarche cauta ) |
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| ( Gould , 1841) |
The white-capped albatross ( Thalassarche cauta ) is a medium-sized seabird from the albatross family native to the southern hemisphere . The species was previously considered polytypic. Based on studies of the relationships within the genus Thalassarche , the Chatham and Salvin albatross , previously classified as a subspecies of the white-capped albatross, are now classified as separate species. In addition to the nominate form Thalassarche cauta cauta, only the subspecies Thalassarche cauta steadi is currently differentiated, but a number of authors also grant it a species status.
Appearance
The white-capped albatross is a medium-sized albatross. It reaches a body length of 90 to 100 centimeters, a wingspan between 210 and 260 centimeters and weighs between 3.2 and 5.1 kilograms. There is no noticeable sexual dimorphism , females tend to be slightly smaller than males.
Adult white-capped albatrosses have a white head, the region around the ears is colored gray, whereby the size of this gray color varies from person to person. This gray coloring makes the white forehead and the white upper head particularly striking. The eye is noticeably dark and surrounded by a black, triangular spot. This facial drawing gives the white-capped albatross a facial expression that appears serious or strained to the human observer.
The plumage of the white-capped albatross is dark on the back, upper wing and tail, and white on the belly, neck and lower wings. The very strong beak is light gray with a yellow tip. The feet and legs are bluish gray.
Young birds are largely similar to adult birds, but are still light to dark gray in color on the back of the head and neck. The black wing tips are also somewhat more pronounced in juveniles than in adult birds.
Occurrence
The nominate form Thalassarche cauta cauta breeds on three islands off the Tasmanian coast. All three islands are now protected. The subspecies Thalassarche cauta steadi breeds on three islands of the Auckland Islands . A well-known colony is on Enderby Island on the South West Cape. Outside of the breeding season, they stay in a region that extends from the 15th to the 60th degree south latitude.
food
The white-capped albatross catches its prey both on the surface and under the water. It dives to a depth of 5 m. Fish and squid play a bigger role in the diet than other albatrosses.
Reproduction
The white-capped albatross breeds annually from the beginning of September to mid-October. The nest is a shallow bump made of mud, guano , feathers, and other materials. The clutch consists of just one egg. This has a whitish skin color and red-brown spots. The breeding season averages 73 days. Most chicks hatch between early December and late December. The young birds fledge between March and early April. Both parent birds are involved in the brood and care of the young bird.
Duration
The IUCN classifies the white-capped albatross as potentially endangered ( near threatened ). The population is estimated at 26,000 sexually mature individuals. The reason for the classification is the relatively small breeding area, which means that extraordinary events in this area can have a strong impact on the overall population. Thalassarche cauta steadi is also classified as Endangered; In 2010 there were 200,000 copies.
supporting documents
literature
- Hadoram Shirihai: A Complete Guide to Antarctic Wildlife - The Birds and Marine Mammals of the Antarctic Continent and Southern Ocean , Alula Press, Degerby 2002, ISBN 951-98947-0-5
- James McQuilken: The Mists of Time. Spitzbergen.de-Verlag, 2012.
Web links
- Thalassarche cauta in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2005. Retrieved on January 24 of 2009.
Single receipts
- ↑ Shirihai, p. 113
- ↑ Shirihai, p. 112
- ↑ Shirihai, p. 110
- ↑ Shirihai, p. 113
- ↑ Birding Downunder 2014 | Polar cruises. Retrieved September 28, 2018 .
- ↑ Shirihai, p. 113
- ↑ BirdLife Factsheet on the White-capped Albatross , accessed November 27, 2010
- ↑ a b James McQuilken: The Mists of Time . Ed .: Rolf Stange. 1st edition. Spitzbergen.de, 2012, ISBN 978-3-937903-15-6 , pp. 137 .