|
The slaty-backed gull (''Larus schistisagus'') is a large white-headed gull that breeds on the western coast of Alaska but travels widely during nonbreeding seasons. It is similar in appearance to the western gull and the glaucous-winged gull. Another alternate name is Pacific gull, though this also applies to a southern hemisphere species, ''Larus pacificus''. Claims have been made as to its (sometimes occasional) presence throughout North America as well as the eastern coast of Asia. On November 3, 2012, an individual was spotted in Finland. The species has only been spotted three times before in Europe.〔(MTV3 News website )〕 The slaty-backed gull is the fourth largest species of gull in the world. It is considered the North Pacific equivalent of the largest gull species, the great black-backed gull. measuring in length, in wingspan and weighing .〔''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.〕 Among standard measurements, the wing chord is , the bill is and the tarsus is .〔 It has a white head, belly, and tail with a dark slaty-gray back and wings with a broad white trailing edge. The wings and back are slightly darker than those of the Western Gull. The underside of the wings features a "string of pearls" pattern along their edges; these can be seen from below when the bird is in flight. Its eyes are yellow. The legs are pink and short when compared with those of similar-looking gulls, and the body appears more stout. The bill is yellow with orange-red subterminal spot. Immature gulls' plumage is brown, similar to the that of the great black-backed gull, but paler, and is practically indistinguishable from the immature herring gull in the field. Like other gulls, the slaty-backed gull is both a forager and a scavenger. ==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 *(Enature: Slaty-backed Gull ) *(For many excellent photos, information and other links on the Slaty-backed Gull ) 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「Slaty-backed gull」の詳細全文を読む スポンサード リンク
|