Black necked swan
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Black-necked swan ( Cygnus melancoryphus ) |
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| Cygnus melancoryphus | ||||||||||||
| ( Molina , 1782) |
The black-necked swan ( Cygnus melancoryphus ) is a bird art from the genus of swans ( Cygnus ), on the family of the Anatidae part (Anatidae). It occurs only in the south of South America.
Appearance
The black-necked swan is 110 to 140 centimeters long and weighs 3.5 to 6.5 kilograms. The males are significantly larger than the females, but otherwise do not show any conspicuous sexual dimorphism . However, older males occasionally develop particularly strong beak bulges.
The species is easy to recognize by the black colored head and neck in connection with the otherwise completely white colored plumage. The eye is framed by a narrow, horizontal white stripe of eyes. The beak is gray and has a large, red-colored fleshy hump at the base. The legs are flesh-colored.
The head and neck feathers of young birds are still black-brown. The remaining parts of the plumage are light gray-brown and interspersed with white feathers. The beak is still gray in these birds. In the first annual dress, the small plumage is already white. However, the wings that have not yet been molten are gray-brown. The beak bulges are still small. In the second annual dress, the animals not yet sexually mature at this point are very similar to the adult birds. It can be clearly seen, however, that the beak bulge is not yet fully developed.
distribution
The breeding area of the black-necked swan is the south of South America . The breeding area extends from central Chile and the south-east of Brazil via Patagonia to Tierra del Fuego and the Falkland Islands . In winter, the birds migrate north from the southernmost breeding areas to Paraguay and southeastern Brazil . Stray visitors have already been observed on the South Shetland Islands and the Antarctic Peninsula . However, it is possible that the observations on the coast of the Antarctic Peninsula were no more than ten to twenty individuals, even if there were more than 60 observations in the period between November 1988 and March 1989. The appearance of this species of swan this far south could be related to a drought in Argentina.
The total population of the black-necked swan is estimated by the IUCN at 26,000 to 100,000 animals. The species is not considered endangered.
Habitat and way of life
The black-necked swan mainly lives in shallow lakes and freshwater swamps, but also brackish water lagoons and - especially in winter - protected sea bays. The main breeding area of the black-necked swans is the low-precipitation pampa region at the foot of the Andes. He mainly inhabits large shallow lakes here. These have cold, clear water, have a rich underwater flora and are usually surrounded by a dense belt of reeds. The black-necked swan feeds mainly on aquatic plants and algae , which it fetches from the shallow water.
Outside the breeding season, the black-necked swan is a very sociable bird. Moulting flocks of this type can contain up to 20,000 individuals in exceptional cases. During the breeding season, however, the black-necked swan is aggressive and defends a territory. Similar to the mute swan , it happens that pairs breed closer to each other.
The breeding business begins in July, that is, in the early spring of the southern hemisphere, and continues into November. The nest is built in the bank cane or on small islands. The female lays three to eight eggs and incubates them alone for about five weeks, while the male carefully guards her. The gray colored chicks are fleeing nests and are often carried on the back by their parents. The young birds fledge after a good three months.
supporting documents
literature
- Tom Bartlett: Ducks and Geese. A guide to management. Crowood, Marlborough 1986, ISBN 0-946284-23-7 .
- Hartmut Kolbe: The world's ducks. 5th edition. Ulmer, Stuttgart 1999, ISBN 3-8001-7442-1 .
- 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
- Robin Woods, Anne Woods: Atlas of Breeding Birds of the Falkland Islands. Anthony Nelson, Shorpshire 1997, ISBN 0904614-60-3 .
Web links
- Cygnus melancoryphus in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2008. Accessed on January 1 of 2009.