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The blue nuthatch (''Sitta azurea'') is a species of bird in the family Sittidae. It is a medium-sized nuthatch, measuring in length. The species, which lacks sexual dimorphism, has dramatic coloration unlike any other member of its genus. Its head is black or blackish-blue dark blue upper parts close to purple with azure feathers. The wings are edged with black. The throat and chest are white or a washed buff color, contrasting with the upper and the belly of a very dark blue; the feathers are generally clear, blue-gray or purplish. The blue nuthatch is found in the Malay Peninsula and in Indonesia, on the islands of Sumatra and Java, inhabiting subtropical or tropical moist lowland forests and subtropical or tropical moist montane forests above in altitude. Its ecology is poorly known, but it feeds on small invertebrates found on trees; reproduction takes place from April to June or July. Three subspecies are distinguished: ''S. a. expectata'', ''S. a. nigriventer'' and ''S. a. azurea'', which vary chiefly in the coloring of their mantles, chests and bellies. The species' apparent closest relatives are the velvet-fronted nuthatch (''S. frontalis''), the yellow-billed nuthatch (''S. solangiae'') and the sulphur-billed nuthatch (''S. oenochlamys''). The population of the species has not been rigorously estimated but the species appears to be at low risk of extinction because of the extent of its distribution. It has been classified as of Least Concern by the International Union for Conservation of Nature. == Taxonomy == The nuthatches constitute a genus – ''Sitta'' – of small passerine birds belonging to the family Sittidae, typified by short, compressed wings and short, square 12-feathered tails, a compact body, longish pointed bills, strong toes with long claws, and behaviorally, by their unique head-first manner of descending tree trunks. Most nuthatches have gray or bluish upperparts and a black eyestripe. ''Sitta'' is derived from the Ancient Greek name for nuthatches, σιττη, ''sittē''. "''Nuthatch''", first recorded in 1350, is derived from "nut" and a word probably related to "hack", since these birds hack at nuts they have wedged into crevices. The genus may be further divided into seven subgenera, of which the blue nuthatch is placed alone in ''Poecilositta'' (Buturlin 1916). The blue nuthatch was first described in 1830 under its current binomial name, ''Sitta azurea'', by the French naturalist René Primevère Lesson (1794–1849). In 2006, ornithologist Edward C. Dickinson proposed a revision of the nuthatch genus, in which certain species would be split off into separate genera, based on distinct morphological traits. He suggested as candidates the velvet-fronted nuthatch (''Sitta frontalis'') and the blue nuthatch, the morphology of which he describes as "rather aberrant ... in spite of a character trait (white edges to wing feathers) shared with ''Sitta formosa''", and that doing so might, in turn, require ''S. Formosa'' (the beautiful nuthatch) to be split off as well. He stated, however, that a molecular study would be warranted prior to any re-classification. In 2014, Eric Pasquet, ''et al''. published a phylogeny based on examination of nuclear and mitochondrial DNA of 21 nuthatch species. The position of the blue nuthatch within the genus was not established with certainty, having a far lower statistical association than many others in the model. Nevertheless, under the findings the species appears best represented by a clade comprising the velvet-fronted nuthatch and the sulphur-billed nuthatch (''S. oenochlamys''), and probably the yellow-billed nuthatch (''S. solangiae''), despite not being in the study's sample group. These tropical Asian nuthatches are themselves a sister clade to one comprising the subgenus ''Sitta'' (''Micrositta'') (sometimes called the ''canadensis'' group), plus the brown-headed nuthatch (''S. pusilla'') and the pygmy nuthatch (''S. pygmaea''). The blue nuthatch has three recognized subspecies: * ''S. a. expectata'' (Hartert, 1914), described in 1914 by German ornithologist Ernst Hartert as ''Callisitta azurea expectata'' from a holotype taken in the Malay Peninsula's Semangko Pass in Pahang; it is also found in Sumatra;〔(【引用サイトリンク】title=International Ornithological Congress World Bird List, Version 4.2 )〕 * ''S. a. nigriventer'' (Robinson & Kloss, 1919), described in 1919 by British zoologists Herbert Christopher Robinson and Cecil Boden Kloss as ''Poliositta azurea nigriventer'' from a holotype taken at Mount Gede in West Java, Indonesia.〔 British ornithologist William Swainson had described the subspecies under the name ''dendrophila flavipes'' in 1838, but the name has subsequently been little used, and can be considered a ''nomen oblitum'' ("forgotten name"); * ''S. a. azurea'' (Lesson, 1830), the nominate subspecies, was described in 1830 by René-Primevère Lesson〔 from a specimen possibly taken on the Arjuno-Welirang stratovolcano; inhabits central and eastern Java.〔 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「blue nuthatch」の詳細全文を読む スポンサード リンク
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