Chinese nuthatch

The Chinese nuthatch was described in 1865 by the French ornithologist Jules Verreaux, based on specimens sent from Beijing by the missionary Armand David in 1862,[3][4] who also referred to it as Sitta pekinensis in 1867.[5] Verreaux described the species as close to red-breasted nuthatch (Sitta canadensis) but with long, silky plumage, and thus gave the specific name "villosa", from the Latin for "hairy". German ornithologist Hans Edmund Wolters proposed the division of the genus Sitta into subgenera in 1975–1982. The Chinese nuthatch is placed in Sitta (Micrositta).[6] According to the International Ornithological Congress there are three subspecies:[7]

• Sitta villosa villosa (Verreaux, 1865), the nominal subspecies, is described in 1865 by Jules Verreaux, ranges from south-east Siberia to north-central and north-east China and Korea.[7]
• Sitta villosa bangsi (Stresemann, 1929), described in 1929 by the German ornithologist Erwin Stresemann based on a specimen from northeastern Qinghai,[8] originally as a subspecies of the red-breasted nuthatch. This subspecies is distributed over the central China.[7]
• Sitta villosa corea (Ogilvie-Grant, 1906), described by the Scottish ornithologist William Robert Ogilvie-Grant from specimens from 180 km (110 mi) southeast of Seoul. It is found on the Korean peninsula and in southeast Siberia.[7] This taxon is often considered a variant of the nominate subspecies, but Nazarenko suggested in 2006 that it should be retained as valid,[9] which was endorsed in the 2014 fourth edition of the Howard and Moore Complete Checklist of the Birds of the World, and later in version 5.2 (April 2015) of the International Ornithological Congress classification.[7]

The Japanese ornithologist Toku Tarô Momiyama also later used the name Sitta villosa yamashinai (Momiyama, 1931), but this name is not associated with any valid scientific description and therefore is a nomen nudum.[2]

In 1998, Eric Pasquet studied the cytochrome-b of the mitochondrial DNA of a dozen nuthatch species, including the various species of the Sitta canadensis group,[10] which are also those that comprise the subgenus Micrositta: canadensis, villosa, yunnanensis, whiteheadi, krueperi and ledanti.[6] The Yunnan nuthatch (S. yunnanensis) is not included in the study. Pasquet concludes that the Chinese nuthatch is phylogenetically related to the Corsican nuthatch (S. whiteheadi) and the red-breasted nuthatch, these three species form the sister group of a clade including Krüper's nuthatch (S. krueperi) and the Algerian nuthatch (S. ledanti). The first three species would even be close enough to be conspecific. For the sake of taxonomic stability, however, all retain their status as species in their own right.[11] In 2014, Eric Pasquet and colleagues published a phylogeny based on nuclear and mitochondrial DNA of 21 nuthatch species and confirmed the relationships of the 1998 study within the "canadensis group", adding the Yunnan nuthatch, which was found to be the most basal species of the group.[12]

With its phylogeny established, Pasquet concludes that the paleogeographic history of the group would be as follows: the divergence between the two main clades of the "canadensis group" appears to have occurred more than five million years ago, at the end of the Miocene, when the common ancestor of krueperi and ledanti entered the Mediterranean basin at the time of the Messinian salinity crisis; the two species diverged 1.75 million years ago. The other clade split into three, with populations leaving Asia for the east, giving rise to the red-breasted nuthatch, and then from the west, about one million years ago, marking the separation between the Corsican and Chinese nuthatches.[10]

The Chinese nuthatch is a small nuthatch, measuring 11.5 cm (4.5 in) in length.^{[fn. 1]} The upperparts of the Chinese nuthatch are blue-gray, with the crown shiny black to dark gray; the underparts are light, ranging from dull buff-gray to cinnamon orange. The coloration varies a bit depending on the sex, plumage wear and subspecies. The species has a marked white supercilium, as well as a more or less well defined black eyestripe. The bill is thin and pointed, with the edge of the upper mandible (the culmen) straight, which may give the impression that the tip of the bill is rising upwards.[13] The bill is slate-black, with the base of the lower mandible blue-gray. The iris is brown to dark brown, and the legs and toes are dull, blue-gray to brownish-gray.[13]

There is a marked sexual dimorphism: the male has a very black crown and a clear black eyestripe framing a contrasting white supercilium, while in the female the crown is barely darker than the rest of the upperparts in fresh plumage, becomes a darker and more contrasting sooty-grey, especially on the forehead, and in some cases the entire crown is sooty-black. Its eyestripe is also less well defined, duller, and its supercilium thinner. The female is overall duller than the male, notably with the scapulars less vivid, the wing feathers edged with brown and the underparts darker and less colored. The juvenile male has a blacker crown than the darker female, but still less black and less bright than the adult male; its underparts are darker and more cinnamon-colored. In the nominate subspecies, juveniles also have cinnamon edging on their wing feathers, whereas the adult feather edges are generally duller, tending to gray.[13] In the subspecies S. v. bangsi, adults have cinnamon feather margins, and are overall more colorful than subspecies S. v. villosa, with the male having orange-cinnamon and the female dull buff-cinnamon and dull underparts. However, in late winter, both subspecies have paler and fairly similar colorations.[13] The subspecies S. v. corea is paler, more grayish, and smaller than the nominate subspecies[13][9]

This species is locally found in sympatry with the Eurasian nuthatch (S. europaea), but differs from it in its smaller size, clearly visible white supercilium, black crown in males, and relatively plain underparts, lacking the reddish undertail coverts and flanks. In the west of its range, the Chinese nuthatch can also be found with Przevalski's nuthatch (S. przewalskii), and both have brightly cinnamon-colored underparts. The Chinese nuthatch is easily distinguished by its black eyestripe, while Przevalski's nuthatch has very light cheeks contrasting with the breast.[13] The Chinese nuthatch is phylogenetically and morphologically very close to the Corsican nuthatch, which is, however, endemic to Corsica and generally has much less vivid underparts; a Chinese nuthatch in worn plumage has underparts that are just more buff than a Corsican nuthatch in fresh plumage. Both species are closely related to the red-breasted nuthatch, which has even brighter underparts, with a more prominent eye streak.[13]

• Similar or phylogenetically related species
• 
  Przevalski's nuthatch (S. przewalskii)
• 
  Corsican nuthatch (S. whiteheadi)
• 
  Red-breasted nuthatch (S. canadensis)

The Chinese nuthatch sings on the top of pine and spruce trees. British ornithologist Simon Harrap gives three basic types of calls. The first is a harsh, prolonged schraa, schraa call, reminiscent of the Eurasian Jay (Garrulus glandarius), and similar to some calls found in the Corsican nuthatch, Algerian nuthatch, and Krüper's nuthatch. Given, in agitation or excitement, singly or in irregular series at intervals of 0.31-1 second. The second type is a various quiet, conversational, single short units, more melodic or piping and repeated in series of whip, whip whip... or quip-quip-quip, sometimes becoming a quit, quit... squeak. The song is composed of this type of calls, in number from five to thirty, the volume increasing in the first part of the song. Small ascending whistles are also emitted, at a rate of seven notes per second and for 1.5 to 2.25 seconds, sometimes introduced by a higher note, forming a tsi-pui-pui-pui-pui.... A variant is a much flatter, less musical and more monotous rattle (c. 12 units per second), duiduiduidui..., recalling song variants of chestnut-vented nuthatch in speed of delivery and duration, but a little mellower and lower-pitched. The last type of call consists of short, nasal notes, quir, quir, produced in long, very rapid series, or in an irregular manner.[13]

A Chinese nuthatch capturing an insect with its beak.

In summer, the Chinese nuthatch feeds almost exclusively on insects, which are also the sole source of food for the young. From April to August, studies in China showed that 98.5% of its diet consisted of insects, including beetles (Coleoptera), Hymenoptera, butterflies, bugs (Heteroptera), Homoptera (including aphids and Cicadidae), Neuroptera and flies (Diptera). It consumes larger insects by holding them with its legs and shredding them with its bill; it can also capture insects in flight. Like other nuthatches, the Chinese nuthatch stores food.[14] In winter, the Chinese nuthatch's diet consists primarily of nuts, seeds, and tree fruits. The species often takes part in mixed-species foraging flocks in winter, where it is observed in pairs.[13][14]

In Jilin, the breeding season takes place from late April to early May. The nest is usually placed high in the cavity of a conifer (more than 9 m (350 in) above the ground, on average), but can also be built in a rotten stump or in an old building. Nest entrance is about 35 mm (1.4 in) in diameter (does not apparently, daub the nest hole with mud or resin). Both partners build the nest within seven to eight days, making a bowl from plant fibers, feathers, and grasses. The egg–laying has four to nine eggs – usually a clutch of five or six: eggs white, marked with reddish-brown and measuring 15 mm–17 mm × 12.5 mm–13 mm (0.59 in–0.67 in × 0.49 in–0.51 in). The female incubates alone while the male feeds her, and the young hatch from the egg after 15–17 days of incubation. Both parents participate in their feeding, and raise only one brood in a year.[13]

A feather mite, Pteroherpus surmachi, was described from the Chinese nuthatch in 2011 by Russian arachnologist Sergei V. Mironov.[15]