Herring head gull
| Herring head gull | ||||||||||||
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Herring-headed gull ( Chroicocephalus novaehollandiae ) |
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| Chroicocephalus novaehollandiae | ||||||||||||
| ( Stephens , 1826) |
The herring head gull ( Chroicocephalus novaehollandiae , syn .: Larus novaehollandiae ) is a medium-sized, white and gray-drawn Australian gull species . It is very similar to the somewhat smaller New Zealand red-billed gull , from which it also differs somewhat in its beak shape. However, the range of the two species only overlaps in the region of Tasmania.
There are two subspecies for the herring head gull. The somewhat larger subspecies Chroicocephalus novaehollandiae fosteri breeds in northern Australia, on New Caledonia and the Loyalty Islands .
Appearance
Herring head gulls reach a body length between 36 and 44 centimeters. The wings are between 26.8 and 31.9 inches long. The wingspan is 91 to 96 centimeters. They weigh between 265 and 315 grams. The males tend to be slightly larger and heavier than the females, although the body dimensions of the two sexes overlap.
Adult herring head gulls have a white head, a white tail, and a white underside of the body. The mantle and wing covers are pale gray. The wings are black with large white spots. The beak and feet are bright red. The eyes are yellowish white with a narrow red eye ring. Non-breeding birds are usually slightly duller in color and have darker eye rings. Outside of the breeding season, they also have a dark spot on their beak, which is individually very variable in shape.
Fledglings have scaly, brownish markings on their wings. Otherwise they are very similar to the adult birds. The beak and eyes are usually black to dark brown and their feet are still yellowish brown.
Distribution and existence
Herring head gulls breed on the coasts, islands and great lakes of Australia, Tasmania and New Caledonia. They are only short-haul migrants .
The herring head gull population appears to be increasing in general. In the early 1990s, around 500,000 pairs were breeding in 200 breeding colonies in Australia.
Way of life
The herring head gull is a colony breeder. Solitary breeding pairs are only very rarely observed. It is often mated with the partner bird from last year and also uses the same breeding site as the year before. The nests are usually built on the ground, but can occasionally be in bushes, where they are built up to 2.5 meters above the ground. The species is capable of raising offspring all year round. Usually, however, the breeding season in western Australia falls between March and November.
The clutch consists of one to five eggs, which are incubated for a period of 21 to 27 days. The young birds remain in the breeding colony for four weeks. They are then fed by the parent birds outside the breeding colony for a further two weeks. They are usually sexually mature at three to four years of age.
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 .
Single receipts
Web links
- Larus novaehollandiae inthe IUCN 2013 Red List of Threatened Species . Listed by: BirdLife International, 2012. Retrieved December 30, 2013.