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The American kestrel (''Falco sparverius''), sometimes colloquially known as the sparrow hawk, is a small falcon, and the only kestrel found in the Americas. It is the most common falcon in North America, and is found in a wide variety of habitats. At long, it is also the smallest falcon in North America. It exhibits sexual dimorphism in size and plumage, although both sexes have a rufous back with noticeable barring. Juveniles are similar in plumage to adults. The American kestrel hunts by hovering in the air with rapid wing beats or perching and scanning the ground for prey. Its diet typically consists of grasshoppers, lizards, mice, and small birds (e.g. sparrows). It nests in cavities in trees, cliffs, buildings, and other structures. The female lays three to seven eggs, which both sexes help to incubate. It is a common bird to be used in falconry, especially by beginners. Though not as aggressive a hunter as many other larger falcons, proper training and weight control by the falconer allows many kestrels to become effective hunters of birds in the size range of sparrows and starlings, with occasional success against birds up to approximately twice their own weight. Its breeding range extends from central and western Alaska across northern Canada to Nova Scotia, and south throughout North America, into central Mexico and the Caribbean. It is a local breeder in Central America and is widely distributed throughout South America. Most birds breeding in Canada and the northern United States migrate south in the winter. It is an occasional vagrant to western Europe. ==Description== The American kestrel is the smallest falcon in North America and, under traditional classification, is the smallest raptor in America. The American kestrel is sexually dimorphic, although there is some overlap in plumage coloration between the sexes. The bird ranges from in length with a wingspan of . The female kestrel is larger than the male. The male weighs , as opposed to the female which weighs . In standard measurements, the wing bone is long, the tail is and the tarsus is .〔(American Kestrel, Life History, All About Birds – Cornell Lab of Ornithology ). Allaboutbirds.org. Retrieved on 2013-02-25.〕 In contrast to many other raptor species, the sexes differ more in plumage than in size. Males have blue-grey wings with black spots and white undersides with black barring. The back is rufous, with barring on the lower half. The belly and flanks are white with black spotting. The tail is also rufous, with a white or rufous tip and a black subterminal band.〔(【引用サイトリンク】title=American Kestrel, ''Falco sparverius'' )〕 The back and wings of the female American kestrel are rufous with dark brown barring. The undersides of the females are creamy to buff with heavy brown streaking. The tail is noticeably different from the male's, being rufous in color with numerous narrow dark black bars. Juveniles exhibit coloration patterns similar to the adults'.〔 In both sexes, the head is white with a bluish-grey top. There are also two narrow, vertical black facial markings on each side of the head, while other falcons have one.〔Tveten & Tveten (2004), p. 210〕 Two black spots (ocelli) can be found on each side of the white or orangish nape.〔Clark & Wheeler (2001), p. 252〕 The function of these spots is debated, but the most commonly accepted theory is that they act as "false eyes", and help to protect the bird from potential attackers. The wings are moderately long, fairly narrow, and taper to a point. 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「American kestrel」の詳細全文を読む スポンサード リンク
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