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Worthen's sparrow (''Spizella wortheni'') is a species of American sparrow that is endemic to northeastern Mexico. It was first described by Robert Ridgway in 1884 and named for the American naturalist Charles K. Worthen. This small bird has been listed as endangered by the IUCN since 1994.〔IUCN Red List: "Worthen's Sparrow." http://www.iucnredlist.org/search/details.php/20663/all〕 == Description == ''Spizella wortheni'' can range in length from 12.5 to 14 cm. It is identifiable by its distinctive head pattern. It has a grey head with a rufous crown, a brown postocular stripe and a pink bill. It has grey-brown upperparts, with dark brown streaks. It has a grey bottom, and dark brown wings and tail. Its wings are "edged paler, with broad whitish to pale buff wing-bar, buffy-rufous tertial and secondary edging, and greyish lesser coverts".〔(【引用サイトリンク】title=Worthen's Sparrow )〕 Juveniles are characterized by brownish colouration of the head and chest, with dusky streaking on the head and dark brown streaking on the chest and flanks. The song is a dry, chipping trill of 2–3 seconds duration and is described as a cross between that of the field sparrow and that of the chipping sparrow. The species is similar in appearance to the field sparrow (''Spizella pusilla''). However, they differ in plumage, habitat, and song. The species nests from May to July and usually lays three or four eggs. Single-species flocks form after the breeding season and are strongly attracted to permanent sources of water. The species is not migratory; however, a few sightings of individuals have taken place throughout the northwestern region of Mexico. Only one individual has ever been identified (shot) in the United States, and it was by Rieber on June 16, 1884, near Silver City, New Mexico.〔 This individual, the first of the species to be described, is the type specimen. 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「Worthen's sparrow」の詳細全文を読む スポンサード リンク
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