Glaucous-winged Gull

From Wikipedia, the free encyclopedia
Glaucous-winged Gull
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Charadriiformes
Family: Laridae
Genus: Larus
Species: L. glaucescens
Binomial name
Larus glaucescens
(Naumann, 1840, North America)

The Glaucous-winged Gull (Larus glaucescens) is a large, white-headed gull residing from the western coast of Alaska to the coast of Washington. It also breeds on the northwest coast of Alaska, in the summertime. During non-breeding seasons they can be found along the coast of California. It is a close relative of the Western Gull and frequently hybridizes with it, resulting in identification problems—particularly in the Puget Sound area. This species also hybridizes regularly with the Herring Gull in [Alaska. Both hybrid combinations resemble the Thayer's Gull. Glaucous-winged Gulls are thought to live about 15 years. An adult bird returned to Sea World in San Diego each winter for 17 years. One individual, notable because he had only one leg, lived at least 30.[citation needed]

The Glaucous-winged Gull is rarely found far from saltwater. It is a large bird, being close in size to the Herring Gull, with which it has a superficial resemblance, and the Western Gull, to which it is likely most closely related. It measures 50–68 cm (20–27 in) in length and 120–150 cm (47–59 in), with a body mass of 730–1,690 g (1.61–3.73 lb).[2][3][4] It weighs around 1,010 g (2.23 lb) on average.[3] Among standard measurements, the wing chord is 39.2 to 48 cm (15.4 to 18.9 in), the bill is 4.6 to 6.4 cm (1.8 to 2.5 in) and the tarsus is 5.8 to 7.8 cm (2.3 to 3.1 in).[4] It has a white head, neck, breast, and belly, a white tail, and pearly-gray wings and back. The term glaucous describes its colouration. The ends of its wings are white-tipped. Its legs are pink and the beak is yellow with a red subterminal spot. The forehead is somewhat flat. During the winter, the head and nape appears dusky, and the subterminal spot becomes dark. Young birds are brown or gray with black beaks, and take four years to reach full plumage.

Glaucous-winged gull, juvenile

The Glaucous-winged Gull nests in the summer, and each pair produces two or three chicks which fledge at six weeks.

It feeds along the coast, scavenging for dead or weak animals, fish, mussels and scraps. Its cry is a low-pitched "kak-kak-kak" or "wow", or a more high-pitched wailing.

It is an exceptionally rare vagrant to the Western Palearctic region, with records from Morocco, the Canary Islands and, most recently, from Britain in the winters of 2006/2007 and 2008/2009. The 2008/2009 record was from Saltholme Pools, Cleveland, and attracted hundreds of twitchers.

References

  1. ↑ BirdLife International (2012). "Larus glaucescens". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013. 
  2. ↑ (2011).
  3. ↑ 3.0 3.1 CRC Handbook of Avian Body Masses by John B. Dunning Jr. (Editor). CRC Press (1992), ISBN 978-0-8493-4258-5.
  4. ↑ 4.0 4.1 Gulls: Of North America, Europe, and Asia by Klaus Malling Olsen & Hans Larsson. Princeton University Press (2004). ISBN 978-0691119977.

Further reading

Identification

  • King, Jon (2007) Identification of Glaucous-winged Gull: a photo-gallery Birding World 20(2):64-72

External links

Wikimedia Commons has media related to Larus glaucescens.
This article is issued from Wikipedia. The text is available under the Creative Commons Attribution/Share Alike; additional terms may apply for the media files.