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The American crow (''Corvus brachyrhynchos'') is a large passerine bird species of the family Corvidae. It is a common bird found throughout much of North America. American crows are the new world counterpart to the carrion crow and hooded crow, occupying similar niches in the ecosystem. It is one of several species of corvid that are entirely black, though it can be distinguished from the other two such birds in its range—from the common raven (''C. corax'') by size and behavior and from the fish crow (''C. ossifragus'') by call (but see below). American crows are common, widespread and adaptable, but they are highly susceptible to the West Nile virus. They are monitored as a bioindicator. Direct transmission of the virus from American crows to humans is not recorded to date, and in any case not considered likely. Although the American crow and the hooded crow are very similar in size, structure and behavior, their calls are different. The American crow nevertheless occupies the same role the hooded crow does in Eurasia. ==Taxonomy== The American crow was described by Christian Ludwig Brehm in 1822.〔''Corvus brachyrhynchos''. Wikispecies〕 Its scientific name means literally "short-billed crow", from Ancient Greek ''brachy-'' (βραχυ-) "short-" and ''rhynchos'' (ρυνχος) "billed".〔 The northwestern crow (''C. caurinus'') is very closely related to the American crow. Its ancestors became separated by Ice Age glaciation west of the Rocky Mountains. It is endemic to Pacific temperate rain forests where it all but replaces the American crow. Only in the Seattle region do they co-occur to any extent. In form the two species are much alike. There is a marked difference in voice.〔 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 crow」の詳細全文を読む スポンサード リンク
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