The Eurasian nuthatch eats mainly insects, particularly caterpillars and beetles, although in autumn and winter its diet is supplemented with nuts and seeds.

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 nuthatches are a family of similar-looking birds with short tails and wings, compact bodies and longish pointed bills.

[8] In 2014, Eric Pasquet and colleagues published a phylogeny based on examination of nuclear and mitochondrial DNA of 21 nuthatch species.

[10] The fossil record for nuthatches is sparse, and in Europe is limited to the extinct Sitta senogalliensis from the Lower Miocene in Italy and somewhat later material from France; the family appears to be of relatively recent origin.

[11] The large, white-breasted S. e. arctica of north east Siberia is distinctive in appearance and genetically, and may be another subspecies group or even a separate species.

[3] 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,[11] but S. e. arctica is quite distinctive.

[11] 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.

[3] 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.

[3] 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.

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.

In the same area, the Krüper's nuthatch (S. krueperi) is smaller, with a dark crown and a large russet patch on the breast.

In southwest China, the chestnut-vented nuthatch (S. nagaensis) is very similar to the torchepot, but has darker upperparts, less white on the face, and more greyish underparts.

[3] The song of the distinctive S. e. arctica is said to be noticeably different from that of its relatives, which would help to establish whether it is a full species, but there has been insufficient research into its vocalizations.

[17] The Eurasian nuthatch's breeding range extends across temperate Eurasia from Great Britain (but not Ireland) to Japan.

[11] It has occurred as a vagrant in Lebanon[1] and the Channel Islands, and the nominate race has been recorded a few times in Finland where S. e. asiatica is the normal form.

[12] Most populations are sedentary, apart from some post-breeding dispersal of young birds, and there is a reluctance to cross even short stretches of open water.

[11] The preferred habitat is mature woodland with large, old trees, which provide extensive growth for foraging and nesting holes.

Unusual habitats include dwarf juniper in Mongolia and rocky terrain in a limited part of southern Siberia.

[12] Despite the lifelong pairing, genetic research in Germany showed that at least 10% of the young in the study area were fathered by another male, usually from an adjacent territory.

The nest site is typically 2–20 m (7–66 ft) above the ground and has a deep base of pine bark or chips of other wood, rarely supplemented with dry plant material.

[23] The sedentary nature of this species means that juveniles can only acquire a territory by finding a vacant area or replacing a dead adult.

In Europe, young birds almost always move to unoccupied habitat, but in the larger territories of Siberia most live within the breeding range of an adult pair.

[27] Sizeable hard food items like nuts or large insects are wedged into crevices in tree bark and smashed with the strong bill.

[3] Cached food may sometimes include non-plant material such as pieces of bread, caterpillars and grubs, the larvae being incapacitated by battering.

[24] In areas where common hazel is the prevalent tree species, there is a similar pattern of adult survival and loss of juvenile birds in years with poor nut production.

The perpetrators were not identified, but the main single predator of tit nests in the same study was the great spotted woodpecker.

The large numbers and huge breeding range mean that this species is classified by the International Union for Conservation of Nature as being of least concern.