Ivory Gull
| Ivory Gull | ||||||||||||
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Ivory Gull ( Pagophila eburnea ) |
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| Systematics | ||||||||||||
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| Scientific name of the genus | ||||||||||||
| Pagophila | ||||||||||||
| Kaup , 1829 | ||||||||||||
| Scientific name of the species | ||||||||||||
| Pagophila eburnea | ||||||||||||
| ( Phipps , 1774) |
The ivory gull ( Pagophila eburnea ) is a species of the gulls (Larinae) and the only recent representative of the genus Pagophila . It is a breeding bird of the Arctic , which occurs only as a rare exceptional guest in Europe. In Fennoscandinavia and Great Britain there are observations almost every year, in Central Europe the Netherlands is the country with the most frequent sightings of this seagull species.
description
The Ivory Gull is 40 to 44 centimeters tall, the wingspan is between 110 and 120 centimeters and the weight is 450 to 690 grams. The silhouette, which is reminiscent of that of the kittiwake, is striking . The adult animal is completely white. In the first winter dress it shows itself with a white plumage with regularly arranged brown-black points and a "dirty" looking face, young birds are also feathered. The legs are short and black.
habitat
The Ivory Gull breeds on islands in the Arctic. Breeding areas can be found in Canada, the east and north of Greenland, Svalbard, on the Franz-Joseph-Land to Severnaya Zemlya . It also overwinters predominantly in the Arctic. The breeding colony closest to Europe is located in the extreme northeast of Svalbard .
During the summer half-year, individual individuals stay up to the pole. In winter, the northern limit of distribution is roughly the pack ice limit. The ivory gulls migrate south with the drift ice, whereby individual individuals also travel much further south. Individuals are sometimes spotted in New York or New Jersey. Occasionally, however, a seagull comes to Central Europe. In 1997 one specimen was observed on the beach of St. Peter-Ording and in 2006 another on the island of Lolland .
nutrition
The diet of the Ivory Gull consists of fish, excrement from seals and polar bears, but also from the remains of their prey as well as carrion and waste.
Reproduction
It is not yet known when Ivory Gulls reach sexual maturity. They lead a monogamous seasonal marriage and lay their nests on gravel and scree beaches and ledges of cliffs directly on the coast and occasionally a little deeper inland. The pairs form at the breeding site. The breeding colonies are small and loosened up.
The nests are shallow depressions that are lined with some plant material. Often some springs are also installed. Laying begins in mid-June and ends in mid-July. The clutch usually consists of two eggs. These are spindle-shaped with a light olive to beige color. They have black, olive and beige-brown spots and blobs, as well as gray markings. The incubation period is 24 to 25 days. Both parent birds breed and feed the young birds. The nestling period is about 30 days.
The oldest ringbird found so far reached the age of 13 years.
Duration
Estimates of the world population of the Ivory Gull vary widely. Numbers between 10,000 and 100,000 breeding pairs and 75,000 not yet breeding individuals are suspected. The European breeding population is 3,100 to 11,000 breeding pairs, although the population trend is unclear. The main focus of European populations is in Russia, where around 2,500 to 10,000 breeding pairs breed. The breeding population in Greenland is estimated at 500 to 1,000 pairs, and Svalbard is home to 50 to 200 breeding pairs. Especially on Svalbard, the population declined at the beginning of the millennium.
The cause of the decline is the regional decline of the polar bear as an important food supplier. It is also assumed that the species reacts sensitively to the increasing tourist use of its breeding area.
supporting documents
literature
- Hans-Günther Bauer, Einhard Bezzel and Wolfgang Fiedler (eds.): The compendium of birds in Central Europe: Everything about biology, endangerment and protection. Volume 1: Nonpasseriformes - non-sparrow birds. Aula-Verlag Wiebelsheim, Wiesbaden 2005, ISBN 3-89104-647-2 .
- Richard Sale: A Complete Guide to Arctic Wildlife. Christopher Helm, London 2006, ISBN 0-7136-7039-8 .
Web links
- Pagophila eburnea in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2008. Accessed on December 22 of 2008.
- Videos, photos and sound recordings of Pagophila eburnea in the Internet Bird Collection
- Ivory Gull on www.oiseaux.net
- Ivory gull feathers
Single receipts
- ↑ Hans-Günther Bauer, Einhard Bezzel and Wolfgang Fiedler (eds.): The compendium of birds in Central Europe: Everything about biology, endangerment and protection. Volume 1: Nonpasseriformes - non-sparrow birds , Aula-Verlag Wiebelsheim, Wiesbaden 2005, ISBN 3-89104-647-2 , p. 577
- ↑ Bauer et al., P. 577
- ↑ Bauer et al., P. 578
- ↑ Bauer et al., P. 578
- ↑ Bauer et al., P. 578
- ↑ Bauer et al., P. 578