It is similar to other treecreepers, and has a curved bill, patterned brown upperparts, whitish underparts, and long stiff tail feathers which help it creep up tree trunks.

The Eurasian treecreeper is insectivorous and climbs up tree trunks like a mouse, to search for insects which it picks from crevices in the bark with its fine curved bill.

Similar in appearance, all treecreepers are small birds with streaked and spotted brown upperparts, rufous rumps and whitish underparts.

The sexes are similar, but the juvenile has duller upperparts than the adult, and its underparts are dull white with dark fine spotting on the flanks.

In appearance, the brown creeper is more like a short-toed treecreeper than a Eurasianone, but a vagrant might still not be possible to identify with certainty given the similarities between the three species.

[2] The Eurasian treecreeper was first described under its current scientific name in 1758 by the Swedish naturalist Carl Linnaeus in the tenth edition of his Systema Naturae.

[4] The binomial name is derived from Ancient Greek kerthios, a small tree-dwelling bird described by Aristotle and others, and Latin familiaris, familiar or common.

[2] Hodgson's treecreeper is a more recent proposed split following studies of its cytochrome b mtDNA sequence and song structure that indicate that it may well be a distinct species from C.

[7] There are nine to twelve subspecies of Eurasian treecreeper, depending on the taxonomic view taken, which are all very similar and often interbreed in areas where their ranges overlap.

The currently recognised subspecies are as follows:[2] The Eurasian treecreeper is the most widespread member of its genus, breeding in temperate woodlands across the Palearctic from Ireland to Japan.

It prefers mature trees, and in most of Europe, where it shares its range with short-toed treecreeper, it tends to be found mainly in coniferous forest, especially spruce and fir.

However, where it is the only treecreeper, as in European Russia,[2] or the British Isles,[5] it frequents broadleaved or mixed woodland in preference to conifers.

[2] The nest has a base of twigs, pine needles, grass or bark, and a lining of finer material such as feathers, wool, moss, lichen or spider web.

Although normally found on trees, it will occasionally hunt prey items on walls, bare ground, or amongst fallen pine needles, and may add some conifer seeds to its diet in the colder months.

[2] It has a distinctive erratic and undulating flight, alternating fluttering butterfly-like wing beats with side-slips and tumbles.

[1] It is common through much of its range, but in the northernmost areas it is rare, since it is vulnerable to hard winters, especially if its feeding is disrupted by an ice glaze on the trees or freezing rain.

In the west of its range it has spread to the Outer Hebrides in Scotland, pushed further north in Norway, and first bred in the Netherlands in 1993.