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The long-tailed jaeger (''Stercorarius longicaudus'') (known as the long-tailed skua outside the Americas) is a seabird in the skua family Stercorariidae. This is the smallest of the skua family at , depending on season and age. However up to of its length can be made up by the tail which may include the tail streamers of the summer adult. The wingspan of this species ranges from and the body mass is .〔''CRC Handbook of Avian Body Masses'' by John B. Dunning Jr. (Editor). CRC Press (1992), ISBN 978-0-8493-4258-5.〕〔(【引用サイトリンク】title=Long-tailed jaeger videos, photos and facts - Stercorarius longicaudus )〕 This species breeds in the high Arctic of Eurasia and North America, with major populations in Russia, Alaska and Canada and smaller populations around the rest of the Arctic. It is a migrant, wintering in the south Atlantic and Pacific. Passage juvenile birds sometimes hunt small prey in ploughed fields or golf-courses, and are typically quite fearless of humans. Two subspecies are listed:〔(【引用サイトリンク】title=''Coursers, noddies, gulls, terns, skuas and sandgrouse'' )〕 *''S. l. longicaudus'' – (Vieillot, 1819): northern Scandinavia and Russia. *''S. l. pallescens'' – (Løppenthin, 1932): eastern Siberia, Arctic North America, and Greenland. They nest on dry tundra or higher fells laying two spotted olive-brown eggs. On the breeding grounds they can be heard making yelping and rattling sounds. Outside of the breeding season they spend most of their time over open ocean and have a harsh ''kreeah'' cry. This bird feeds on fish (mainly caught from other seabirds), smaller birds, food scraps, small mammals, fruit and carrion. On migration, long-tailed jaegers are more likely to catch their own food, and less likely to steal from gulls and terns than larger species. This species is unmistakable as an adult, with grey back, dark primary wing feathers without a white "flash", black cap and very long tail. Adults often hover over their breeding territories. Juveniles are much more problematic, and are difficult to separate from parasitic jaeger over the sea. They are slimmer, longer-winged and more tern-like than that species, but show the same wide range of plumage variation. However, they are usually colder toned than Arctic, with greyer shades, rather than brown. ==References== * * ==External links== *(Oiseaux ) Photo, plates *(Avibase ) * * * 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「Long-tailed jaeger」の詳細全文を読む スポンサード リンク
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