Andean gull
| Andean gull | ||||||||||||
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Andean gull in breeding plumage with a distinctive hand swing pattern |
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| Chroicocephalus serranus | ||||||||||||
| ( Tschudi , 1844) |
The Andean gull ( Chroicocephalus serranus , syn .: Larus serranus ) is a medium-sized, black-headed gull species that breeds in Andean lakes between northern Ecuador and northern Chile and overwinters on large parts of the South American Pacific coast .
description
With a body length of 44–48 cm, the Andean gull is slightly larger than a common gull . The sexes do not differ. In the breeding plumage, the species shows a shiny black head cap, from which a white, interrupted eye ring stands out clearly. The neck and neck are white except for the front back. The underside, which is also white, can be tinged with pink. The mantle and upper wing are light gray. The pattern of the hand wings is unmistakable. The distal part of the hand wing is predominantly white. A black central band runs over the three outer hand wings, which have black tips. The inner hand wings show black subterminal fields and white tips. The pattern from the underside is particularly characteristic: here the distal part of the wing looks almost black with an almost semicircular white mirror on the outer hand wings . The bill, feet and legs are blackish with a dark reddish tinge. The iris is brown.
The black head cap is missing in the winter dress. In some specimens the head is streaked on top; There are black spots in front of the eye and on the back of the ear covers. In youth clothing, the top of the head, neck and front back are speckled brown. The hand wing has a complex, black and white pattern and the arm wings are brown. Legs and feet are also brown. The tail wears a black subterminal band, which is retained even in one year olds.
Distribution and existence
The breeding area of the monotypical Andean gull extends from northern Ecuador southwards through large parts of Peru to western Bolivia , northern Chile and the province of Tucumán in northern Argentina . It breeds there on gravel banks in rivers or on small islands in lakes of the Altiplano at altitudes between 4000 and 5300 m, more rarely at lower altitudes.
Although the world population is not large with possibly less than 50,000 breeding pairs, the species is not considered to be endangered ( “least concern” ) due to its large range . The majority of the population breeds in remote lakes and is therefore little endangered, but locally the species can be exposed to disturbances from agriculture and other human factors.
hikes
Many Andean gulls are resident birds , but the majority overwinter at estuaries, lakes, in swamps and in fields on the Pacific coast. The occurrences there range from northern Ecuador south to the Chilean province of Aisén . Some birds also make their way to the Atlantic coast, but are often overlooked there due to their similarity to other gull species such as the Patagonian gull .
food
The diet of the Andean gull consists of earthworms, insects, amphibians and small fish. Occasionally eggs and young nestlings of neighboring breeding bird species are added. Outside the breeding season, the species feeds on fishing waste, fish and other marine animals.
Reproduction
The breeding season varies depending on the climatic conditions, but is usually between July and August. The species usually breeds in small colonies, sometimes in single breeding pairs. In contrast to other seagull species, there is little noise in the colonies; if there is danger from intruders, the colony is abandoned. The nest can stand between tufts of grass or rocks on overgrown islands, or it can be laid out on a floating platform. The nest spacing is 1–3 m. The clutch consists of 2–3, more rarely 1–4 eggs. As with the gray gull , the eggshell is very fine-pored so that only water vapor can escape.
literature
- 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.
- Gerald S. Tuck, Hermann Heinzel : The sea birds of the world. Paul Parey Publishing House, Hamburg / Berlin 1980, ISBN 3-490-07818-7 .
Web links
- Larus serranus in the endangered Red List species the IUCN 2009. Posted by: BirdLife International, 2009. Accessed January 28, 2012 Design.
- BirdLife International: Species Factsheet - Andean Gull ( Larus serranus ) . Retrieved January 28, 2012.
- Videos, photos and sound recordings of Larus serranus in the Internet Bird Collection
- xeno-canto: Sound recordings - Andean Gull ( Chroicocephalus serranus )