Eurasian Treecreeper

The Eurasian treecreeper, Certhia familiaris, is a diminutive passerine, the sole representative of its genus in the British Isles, where it is simply known as the treecreeper. It boasts a curved bill, intricately patterned brown upperparts, and whitish underparts. Its long, stiff tail feathers are not just for show; they are essential for its unique method of ascending tree trunks.

Identification Tips

This species measures approximately 12.5 cm in length and weighs between 7.0 and 12.9 grams. The sexes appear similar, with juveniles presenting a slightly duller plumage. The Eurasian treecreeper can be distinguished from the similar short-toed treecreeper by its song and subtle differences in plumage, such as a whiter underside and a more pronounced supercilium.

Habitat

The Eurasian treecreeper is found in a variety of woodlands across temperate Eurasia. It shows a preference for mature trees and, in regions where it coexists with the short-toed treecreeper, it is more commonly associated with coniferous forests and higher altitudes.

Distribution

This species is widespread, breeding from Ireland to Japan. It is non-migratory in milder regions but may move southward or to lower altitudes in winter.

Behaviour

The Eurasian treecreeper is a solitary bird in winter, but may form communal roosts during cold spells. It exhibits an erratic flight pattern, characterized by fluttering wing beats interspersed with side-slips and tumbles.

Song & Calls

The contact call is a soft, high-pitched 'sit', while the song is a more complex series of notes including a distinctive 'tsree' with a vibrato quality. The male's song is a mix of twittering notes and whistles.

Breeding

Nesting occurs in tree crevices or behind bark flakes, with a preference for the soft bark of the introduced giant sequoia. The female lays a clutch of five to six pink-speckled white eggs, which are incubated for 13-17 days. Both parents feed the altricial chicks, which fledge after another 15-17 days.

Similar Species

The Eurasian treecreeper can be confused with several other treecreepers, particularly the short-toed treecreeper in Europe and Hodgson's treecreeper in the Himalayas. However, differences in tail patterns, throat coloration, and song are key to distinguishing these species.

Diet and Feeding

Insectivorous by nature, the Eurasian treecreeper forages on tree trunks, starting from the base and working upwards, using its bill to extract insects from bark crevices. It may occasionally join mixed-species flocks in winter, though it does not seem to directly benefit from the foraging of other species.

Conservation status

The Eurasian treecreeper is classified as Least Concern by the IUCN, with an extensive range and a large population that does not appear to be in decline. It is common throughout much of its range, though it can be rare in the northernmost areas and is sensitive to harsh winters.