Yunnan nuthatch
| Yunnan nuthatch | |
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| A representation of the Yunnan nuthatch with fresh plumage | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Passeriformes |
| Family: | Sittidae |
| Genus: | Sitta |
| Species: | S. yunnanensis |
| Binomial name | |
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Sitta yunnanensis Ogilvie-Grant, 1900 |
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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 4,000 m (13,000 ft).
This blue-grey bird can be up to 12 centimetres (4.7 in) 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 170,000 square kilometres (66,000 sq mi), and a 2009 study predicted that its population could decrease by 43.6% to 47.7% by between 2040 and 2069.
The upper parts of the Yunnan nuthatch are blue-grey, including the , 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 12 cm (4.7 in) in length, and its wing chord is 69.5 to 74 millimetres (2.74 to 2.91 in) on male specimens and 67 to 74 millimetres (2.6 to 2.9 in) on female specimens. On males, the tale measures 35 to 41 millimetres (1.4 to 1.6 in) and on females, it measures between 36 and 38 millimetres (1.4 and 1.5 in). Its beak measures between 16.8 and 19.5 millimetres (0.66 and 0.77 in), the tarus is 14.8 to 19 millimetres (0.58 to 0.75 in) in length, and it weighs between 7.5 and 13 grams (0.26 and 0.46 oz).
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.
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Wikipedia