The Eurasian Treecreeper (Certhia familiaris) is a small, bark-camouflaged bird that spirals up tree trunks searching bark crevices for insects. It is a slight, delicate bird, 12–14 cm long with a wingspan of about 17–21 cm and weighing only 8–12 grams, brown-and-white mottled above in a pattern that camouflages it almost perfectly against bark, with a silvery-white underside. The bill is thin and clearly downcurved, adapted for probing bark crevices for prey, while the long, stiff, pointed tail is used as a prop while climbing — much as in a woodpecker — and long, curved claws give a firm grip on the bark; a pale eyebrow stripe completes the face.
Its contact call is a very thin, high, wheezy "tsrii" or "siih" that can be easy to miss, while the song is a short, slightly accelerating trill often rendered as "tit-tit-tit-tsi-rr-titt" ending in a little flourish. Found throughout Sweden, from Skåne to the mountain birch forest in the north, it is a common woodland bird with a population in the hundreds of thousands of pairs and a fully resident species that in winter often joins roaming mixed flocks with Great Tits, Goldcrests and other tits. It breeds in coniferous and mixed forest with mature trees, placing its distinctive nest in a narrow gap behind a flake of loose bark, often on an old spruce or pine, built from twigs, bark and feathers, and will also use specially shaped nest boxes with a slit entrance; the female lays 5–6 eggs and incubates for about 13–15 days, with young fledging in just under three weeks. Its diet is small insects, larvae, spiders and their eggs, picked from bark crevices with the curved bill, with occasional seeds taken in winter. It is best located by its behaviour: landing low on a trunk, spiralling upward as it forages, then flying down to the base of the next tree to start again.
Read about this species in Swedish →