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A falcon () is any one of 37 species of raptors in the genus ''Falco'', widely distributed on all continents of the world except Antarctica. Adult falcons have thin, tapered wings, which enable them to fly at high speed and to change direction rapidly. Fledgling falcons, in their first year of flying, have longer flight feathers, which make their configuration more like that of a general-purpose bird such as a broadwing. This makes it easier to fly while learning the exceptional skills required to be effective hunters as adults. The falcons are the largest genus in the Falconinae subfamily of Falconidae, which itself also includes another subfamily comprising caracaras and a few other species. All these birds kill with their beaks, using a "tooth" on the side of their beaks — unlike the hawks, eagles, and other birds of prey in Accipitridae, which use their feet. Peregrine falcons have been recorded diving at speeds of 200 miles per hour (320 km/h), making them the fastest-moving creatures on Earth.〔"The Speed of Animals" in ''The New Book of Knowledge'', Grolier Academic Reference, 2003, p. 278, ISBN 071720538X〕 Other falcons include the gyrfalcon, lanner falcon, and merlin. Some small falcons with long, narrow wings are called hobbies, and some which hover while hunting are called kestrels. As is the case with many birds of prey, falcons have exceptional powers of vision; the visual acuity of one species has been measured at 2.6 times that of a normal human.〔 The traditional term for a male falcon is 'tercel' (British spelling) or 'tiercel' (American spelling), from Latin ''tertius'' = third because of the belief that only one in three eggs hatched a male bird. Some sources give the etymology as deriving from the fact that a male falcon is about one-third smaller than the female〔(【引用サイトリンク】title=tercel )〕〔"tercel", Oxford Dictionary〕 (Old French ''tiercelet''). A falcon chick, especially one reared for falconry, still in its downy stage is known as an 'eyas' (sometimes spelt 'eyass'). The word arose by mistaken division of Old French ''un niais'', from Latin presumed ''nidiscus'' ("nestling", from ''nidus'' = nest). The technique of hunting with trained captive birds of prey is known as falconry. ==Systematics and evolution== Compared to other birds of prey, the fossil record of the falcons is not well distributed in time. The oldest fossils tentatively assigned to this genus are from the Late Miocene, less than 10 million years ago. This coincides with a period in which many modern genera of birds became recognizable in the fossil record. The falcon lineage may, however, be somewhat older than this, and given the distribution of fossil and living ''Falco'' taxa, is probably of North American, African, or possibly Middle Eastern or European origin. 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「falcon」の詳細全文を読む スポンサード リンク
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