The Eurasian nuthatch or wood nuthatch (Sitta europaea) is a small passerine bird found throughout temperate Asia and in Europe, where its name is the nuthatch. Like other nuthatches, it is a short-tailed bird with a long bill, blue-grey upperparts and a black eye-stripe. It is a vocal bird with a repeated loud dwip call. There are more than 20 subspecies in three main groups; birds in the west of the range have orange-buff underparts and a white throat, those in Russia have whitish underparts, and those in the Far East have a similar appearance to European birds, but lack the white throat.
The preferred habitat is mature deciduous or mixed woodland with large, old trees, preferably oak. Pairs hold permanent territories, and nest in tree holes, usually old woodpecker nests, but sometimes natural cavities. If the entrance to the hole is too large, the female plasters it with mud to reduce its size, and often coats the inside of the cavity too. The 6–9 red-speckled white eggs are laid on a deep base of pine or other wood chips.
The Eurasian nuthatch eats mainly insects, particularly caterpillars and beetles, although in autumn and winter its diet is supplemented with nuts and seeds. The young are fed mainly on insects, with some seeds, food items mainly being found on tree trunks and large branches. The nuthatch can forage when descending trees head first, as well as when climbing. It readily visits bird tables, eating fatty man-made food items as well as seeds. It is an inveterate hoarder, storing food year-round. Its main natural predator is the Eurasian sparrowhawk.
Fragmentation of woodland can lead to local losses of breeding birds, but the species' range is still expanding. It has a large population and huge breeding area, and is therefore classified by the International Union for Conservation of Nature (IUCN) as being of least concern.
The adult male of the nominate subspecies, S. e. europaea is 14 cm (5.5 in) long with a 22.5–27 cm (8.9–10.6 in) wingspan. It weighs 17–28 g (0.6–1 oz). It has blue-grey upperparts, a black eye-stripe and whitish throat and underparts. The flanks and lower belly are orange-red, mottled with white on the undertail. The stout bill is dark grey with a paler area on the base of the lower mandible, the iris is dark brown and the legs and feet are pale brown or greyish. Most other members of the S. e. europaea group differ only in detail from the nominate form, often with respect to the hue of the underparts, but S. e. arctica is quite distinctive. It is large, pale, has a white forehead and a reduced eye-stripe, and it has more white in the tail and wings than any other subspecies. Nuthatches move on trees with short leaps, and do not use their tails for support. In flight, they have a characteristic appearance, with a pointed head, round wings and a short, square tail. Their flight is fast, with wings closed between beats, and is usually of short duration.
S. e. caesia, the most widespread of the western subspecies, has orange-buff underparts except for a white throat and cheeks. The other western forms mainly differ in the exact shade of the underparts, although some southeastern forms also show a white forehead and supercilium. S. e. sinensis and S. e. formosana, of China and Taiwan respectively, have buff underparts like the western races, but have buff, instead of white, throats.
The female is similar in appearance to the male, but may be identified by her slightly paler upperparts, a browner eyestripe and a more washed-out tone to the flanks and lower belly. In the eastern form, S. e. asiatica, some males have buff underparts like the female, and birds with this appearance are difficult to sex in the field.[9] Young birds resemble the female, although their plumage is duller and they have paler legs. Individuals can be reliably sexed as female from about 12 days old by their paler and buffer flanks, or, in some white-breasted subspecies, by the creamier hue of their underparts.
Adults have a complete moult after breeding which takes about 80 days, starting from late May onwards and finishing by late September. The moult period for Siberian birds is more compressed, running from June to mid-September. Fledged juveniles moult some of their wing coverts when they are about eight weeks old.
In much of its range, Eurasian is the only nuthatch present. In southeast Europe and southwest Asia, the western and eastern rock nuthatches are larger and paler than the Eurasian species. They also lack white spots in the tail and are usually found in a different, stony habitat, and Krüper's nuthatch is small and has a black cap and reddish breast patch. In southwest China, the chestnut-vented nuthatch is very similar to the European bird, but is darker above, has less white on the face and has greyer underparts.
