|
The Yunnan nuthatch (''Sitta yunnanensis'') is a species of nuthatch endemic to South-Western China. It was first described by William Robert Ogilvie-Grant in 1900 based on a male holotype, and it occurs in pine forests at altitudes of up to . This blue-grey bird can be up to long, has a distinctive white eyebrow, and exhibits a small degree of sexual dimorphism. This noisy bird's diet consists of insects it finds on pine branches, and it is generally rare but can be locally common. Categorised as a near-threatened species on the IUCN Red List, it has a small range of , and a 2009 study predicted that its population could decrease by 43.6% to 47.7% by between 2040 and 2069. ==Description== The upper parts of the Yunnan nuthatch are blue-grey, including the calotte, despite being separated from the upper mantle by a paler area. It has a thin white eyebrow, which extends to the front of the bird and is above the black eye line. Each eye has a fine white circle around it, and it has a white cheek and throat. The lower parts are pale and unified, and the grey-black beak is sharp and pointed with a yellowish base. Its irises are dark brown, and the legs and feet are grey-brown. The Yunnan nuthatch is a small nuthatch, measuring around in length, and its wing chord is on male specimens and on female specimens. On males, the tale measures and on females, it measures between . Its beak measures between , the tarus is in length, and it weighs between . It exhibits little sexual dimorphism, but when the black eye trait is shown on females, their eyes are duller and greyer than those of males. The plumage is fresh in August and gradually gets worn away until the following spring. In worn plumage, the whitish feathers forming the ends of the eyebrows are worn, and the eyebrow line becomes discontinuous or inconspicuous, and the upper parts of the bird become duller. Its tail feathers and wings wear, but the blue-grey feather tips exist until at least May. The lower parts tarnish and become increasingly "dirty", and become a greyish-white colour. Sometimes, the eyebrow does not fully extend to the front. The eye line becomes narrower, and the cheek of the bird becomes grey, instead of white. The throat remains white, but the underside of the bird becomes duller, and less pale in adult specimens. Adult specimens molt from July to September, and there is sometimes a partial molt between January and February, prior to the breeding season. The giant nuthatch can occur in the same habitat as the Yunnan nuthatch, but lacks a white eyebrow. The chestnut-vented nuthatch is more similar in size to the Yunnan nuthatch than the giant nuthatch, but is different in colour and also lacks a white eyebrow. 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「Yunnan nuthatch」の詳細全文を読む スポンサード リンク
|