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The hen harrier (''Circus cyaneus'') or northern harrier (in the Americas) is a bird of prey. It breeds throughout the northern parts of the northern hemisphere in Canada and the northernmost USA, and in northern Eurasia. This species is polytypic, with two subspecies. Marsh hawk is a historical name for the American form.〔 It migrates to more southerly areas in winter. Eurasian birds move to southern Europe and southern temperate Asia, and American breeders to the southernmost USA, Mexico, and Central America. In the mildest regions, such as France, Great Britain, and the southern US, hen harriers may be present all year, but the higher ground is largely deserted in winter. ==Description== The hen harrier is 〔 long with a wingspan.〔〔 It resembles other harriers in having distinct male and female plumages. The sexes also differ in weight, with males weighing , with an average of , and females weighing , with an average of .〔〔 Among standard measurements, the wing chord is , the tail is and the tarsus is .〔 It is relatively long winged and long tailed, having the longest wing and tail relative to its body size of any raptor occurring in North America.〔 The male of the nominate race, ''C. c. cyaneus'' (Linnaeus, 1766), which breeds in Europe and Asia, is mainly grey above and white below except for the upper breast, which is grey like the upperparts, and the rump, which is white; the wings are grey with black wingtips. The female is brown above with white upper tail coverts, hence females, and the similar juveniles, are often called "ringtails". Their underparts are buff streaked with brown.〔 The race ''C. c. hudsonius'' (Linnaeus, 1766) breeds in North America and is sometimes considered a distinct species, ''C. hudsonius''.〔 The male's plumage is darker grey than that of ''C. c. cyaneus'' and the female is also darker and more rufous.〔 In both North American and Eurasia, the adult male is sometimes nicknamed the "Grey Ghost", because of his striking plumage and spectral aura. The female gives a whistled ''piih-eh'' when receiving food from the male, and her alarm call is ''chit-it-it-it-it-et-it''. The male calls ''chek-chek-chek'', with a more bouncing ''chuk-uk-uk-uk'' during his display flight.〔 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「hen harrier」の詳細全文を読む スポンサード リンク
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