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The American goldfinch (''Spinus tristis''), also known as the eastern goldfinch, is a small North American bird in the finch family. It is migratory, ranging from mid-Alberta to North Carolina during the breeding season, and from just south of the Canadian border to Mexico during the winter. The only finch in its subfamily to undergo a complete molt, the American goldfinch displays sexual dimorphism in its coloration; the male is a vibrant yellow in the summer and an olive color during the winter, while the female is a dull yellow-brown shade which brightens only slightly during the summer. The male displays brightly colored plumage during the breeding season to attract a mate. The American goldfinch is a granivore and adapted for the consumption of seedheads, with a conical beak to remove the seeds and agile feet to grip the stems of seedheads while feeding. It is a social bird, and will gather in large flocks while feeding and migrating. It may behave territorially during nest construction, but this aggression is short-lived. Its breeding season is tied to the peak of food supply, beginning in late July, which is relatively late in the year for a finch. This species is generally monogamous, and produces one brood each year. Human activity has generally benefited the American goldfinch. It is often found in residential areas, attracted to bird feeders which increase its survival rate in these areas. Deforestation also creates open meadow areas which are its preferred habitat. ==Taxonomy== The American goldfinch was one of the many species originally described by Linnaeus in the landmark 1758 10th edition of his work ''Systema Naturae''. It was initially included in the genus ''Spinus'', a group containing New World goldfinches and siskins, but in 1976, ''Spinus'' was merged into the genus ''Carduelis'' as a subgenus. Recent studies resurrect the genus ''Spinus''. Its closest relatives are the lesser goldfinch ''(S. psaltria)'', Lawrence's goldfinch ''(S. lawrencei)'', and the siskins. Although it shares a name with the European goldfinch, the two are in separate subgenera and are not directly related. ''Carduelis'' is derived from ''carduus'', the Latin word for thistle; the species name ''tristis'' is Latin for 'sorrowful'. There are four recognized subspecies of the American goldfinch:〔 * ''S. t. tristis'' is the most common of the subspecies. Its summer range is from southern Canada to Colorado, and east to the Carolinas. Its winter range is from southern Canada south to Florida and central Mexico. * ''S. t. pallidus'' is differentiated from other subspecies by its paler body color, stronger white markings and, in males, a larger black cap. It is slightly larger than ''C. t. tristis''. The summer range is from British Columbia to western Ontario, south to Colorado and west to Oregon. In winter, the range extends from southern Canada and northern California, south to Mexico.〔 * ''S. t. jewetti'' is smaller and darker than the other subspecies. It occurs on the coastal slope of the Cascade Mountains from southern British Columbia to central California, overlapping with the range of ''C. t. pallidus''.〔 * ''S. t. salicamans'' occurs west of the Sierra Nevada range during the summer and in south and central Baja California Peninsula to the Mojave Desert and Colorado Desert in winter. In winter, the plumage of both sexes is browner than other subspecies, and in summer, the male's black cap is smaller than that of other subspecies.〔 This subspecies has been called the willow goldfinch. This seems to be the most ancient extant species of the Meso American Spinus/Carduelis evolutive radiation, whose parental species is Carduelis/Spinus lawrencei. 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 goldfinch」の詳細全文を読む スポンサード リンク
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