|
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, but some live much longer; a bird in British Columbia, for example, lived for more than 21 years,〔 while one in the US state of Washington, lived for at least 22 years, 9 months.〔 The longevity record though, is more than 37 years, for a bird banded as a chick in British Columbia.〔 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 in length and in wingspan, with a body mass of .〔() (2011).〕〔''CRC Handbook of Avian Body Masses'' by John B. Dunning Jr. (Editor). CRC Press (1992), ISBN 978-0-8493-4258-5.〕〔''Gulls: Of North America, Europe, and Asia'' by Klaus Malling Olsen & Hans Larsson. Princeton University Press (2004). ISBN 978-0691119977.〕 It weighs around on average.〔 Among standard measurements, the wing chord is , the bill is and the tarsus is .〔 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. 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== * "National Geographic" ''Field Guide to the Birds of North'' ''America'' ISBN 0-7922-6877-6 *'' Seabirds, an Identification Guide'' by Peter Harrison, (1983) ISBN 0-7470-1410-8 *''Handbook of the Birds of the World Vol 3'', Josep del Hoyo editor, ISBN 84-87334-10-5 *"National Audubon Society" ''The Sibley Guide to Birds'', by David Allen Sibley, ISBN 0-679-45122-6 *(British Columbia Wildlife ) *(Cornell Lab of Ornithology ) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Glaucous-winged gull」の詳細全文を読む スポンサード リンク
|