Cape Gull
| Cape Gull | ||||||||||||
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Cape Gull ( Saundersilarus saundersi ) |
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| Systematics | ||||||||||||
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| Scientific name of the genus | ||||||||||||
| Saundersilarus | ||||||||||||
| Dwight , 1926 | ||||||||||||
| Scientific name of the species | ||||||||||||
| Saundersilarus saundersi | ||||||||||||
| ( Swinhoe , 1871) |
The black-headed gull ( Saundersilarus saundersi , syn .: Chroicocephalus saundersi , Larus saundersi ) or Saunders gull is a small, black-headed gull that is native to the coasts of eastern China . Due to various morphological features and studies of the mitochondrial DNA , it was proposed to place the species in its own genus called Saundersilarus . This has so far been recognized by the Handbook of the Birds of the World Illustrated Checklist, the Howard & Moore Checklist, the Clements Checklist, and BirdLife International. The kind epithet honors the British ornithologist Howard Saunders .
With an estimated 3500-4500 breeding pairs, the world population is small and in decline, the habitats are threatened by increasing, intensive use. The IUCN therefore regards the species as endangered (“vulnerable”).
description
With a length of 30–33 cm, the Cape Gull is somewhat larger than a Little Gull . The wing length is between 268 and 297 mm. The head looks very round; the beak is relatively short and broad with a characteristic bent tip. In flight, the body appears short and oval, the wings long and pointed, the tail narrow. The wings are often held at a slight angle. The flight is tern-like , the shape reminds a little of the rose gull . The sexes do not differ. The species is colored in the second year of life.
In the breeding plumage, adult birds show a black cap with which the white lids contrast, which frame the rear eye in a U-shape. The beak is black; the legs and feet are very dark red. The neck, underside, rump and control feathers are white. The top shows a light, bluish gray. The hand wing pattern is reminiscent of that of the little gull, but the outermost hand wing is usually completely white; sometimes the inside flag is black. The following four wings show black subterminal fields ; in the middle, the black extends a little further up and creates a streaky pattern. There is a relatively wide, white lace hem on the arm wing. From below, the outer hand wing looks white, the middle part of the hand wing black.
In winter dress, the head is white except for a large black ear mark and two brownish or gray cross stripes on the top.
Birds in the first winter have a narrow, black tail band that brightens in the following summer. The upper wing shows a brown stripe on the small arm covers, which widens significantly in the area of the wrist. The large and medium arm covers form two rather inconspicuous bands due to the brown subterminal fields and light lace hems. That of the large arm covers continues on the hand covers. There are also black feather bases on these. The wing is also predominantly black. The black wing tip shows a striped pattern due to the white inner flags of the hand wings, the tips of the outer hand wings are black. An interrupted band of wide, black subterminal fields runs over the inner hand and arm wings. These are strongest on the inner arm wings. The rear edge of the arm wing is broadly white.
In the first winter the head is colored similar to that of adult birds; however, the vertex coloration is less pronounced. In the second summer, the black head cap begins to form. However, this is still strongly interspersed with white on the face. The brown and black areas on the wing recede strongly.
voice
A hard, tern-like kip and a chao , reminiscent of the calls of the Chlidonias species, are described as vocal utterances .
Distribution and existence
The breeding grounds of the Cape Gull were only discovered in 1984; they are located in salt marshes and at river mouths in eastern China. The brood distribution includes the coastal areas on the northern part of the Yellow Sea in the Chinese provinces of Shandong (200 breeding pairs), Hebei (25 bp.), Liaoning (600–700 bp.) And Jiangsu (300–750 bp.). There were two breeding records in South Korea in the 1990s ; there may also be breeding occurrences in North Korea .
The species used to be very numerous in southeastern China. After a significant decline, the world population is now estimated at 3500-4500 breeding pairs or 7100-9600 individuals. Seven colonies are known, the most important of which are in the Yancheng Nature Reserve in Jiangsu and the Shuangtai Hekou National Nature Reserve in Liaoning. In October 2001, 1317 birds were counted in the latter area. All colonies are threatened by intensive exploitation, especially oil and salt extraction and shrimp farming . In addition, there is pollution from oil and industrial wastewater. Furthermore, the species is severely affected by other human disorders such as egg collection, which affects the breeding success. The habitats in the winter quarters are also threatened by the increased use of the intertidal zone and the spread of human settlements.
hikes
Little is known about the migratory behavior of the species. It moves east and south and can then be found southwest to Hainan and North Vietnam, east to Korea and southern Japan with individual records in central Honshu . Winter populations are most extensive in December, and they rapidly decline in late March. The largest concentrations are found with up to 2000 birds in the Yancheng Nature Reserve, where the species also breeds, and with 1000 individuals in Kyushu .
Way of life
The way of life of the Cape Gull is largely unknown. The species breeds mainly in salt marshes, which are dominated by sod , less often in inland waters close to the coast. They probably look for their food mainly in the intertidal zone. It is believed to be made up of crustaceans and small fish. The clutch usually consists of 3, more rarely 1–6 eggs, with clutches with more than five eggs presumably mostly coming from two females.
literature
- Klaus Malling Olsen, Hans Larsson: Gulls of Europe, Asia and North America , Helm Identification Guides, Christopher Helm, London 2003 (corrected new edition from 2004), ISBN 978-0-7136-7087-5 , pp. 475-480.
- Josep del Hoyo , Andrew Elliott, Jordi Sargatal (eds.): Handbook of the Birds of the World. Volume 3: Hoatzin to Auks. Lynx Edicions 1996, ISBN 978-84-87334-20-7 , p. 617.
- J.-M. Pons, A. Hassanin, P.-A. Crochet: Phylogenetic relationships within the Laridae (Charadriiformes: Aves) inferred from mitochondrial markers . Molecular Phylogenetics and Evolution, Volume 37, Issue 3, December 2005, pages 686-699 doi : 10.1016 / j.ympev.2005.05.011
- Gerald S. Tuck, Hermann Heinzel : The sea birds of the world. Paul Parey Publishing House, Hamburg / Berlin 1980, ISBN 3-490-07818-7 .
Individual evidence
- ↑ Pons et al. (2005), p. 697, see literature
- ↑ a b c d e f g Olsen / Larsson (2003), p. 478, see literature
- ↑ Olsen / Larsson (2003), p. 479, see literature
- ↑ a b Olsen / Larsson (2003), p. 475, see literature
- ↑ a b c d Olsen / Larsson (2003), p. 475f, see literature
- ↑ a b c d Del Hoyo et al. (1996), p. literature
- ↑ a b c Bird Life Species Factsheet, see web links
Web links
- Saundersilarus saundersi in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2010. Retrieved on February 6, 2012 found.
- BirdLife International: Species Factsheet - Saunders Gull ( Saundersilarus saundersi ) . Retrieved February 6, 2012.
- Videos, photos and sound recordings of Larus saundersi in the Internet Bird Collection
- Larus saundersi photos in the Oriental Bird Club image database , accessed February 6, 2012