Treecreeper

The treecreeper (Certhia familiaris) is, as its name suggests, a woodland bird that spends much of its time on tree trunks and branches. Although not a rare bird it is not easy to spot, given that it is a small bird with plumage that blends well with the bark of trees.

It is found throughout the British Isles, except for the far northern and western isles, where there are not all that many trees. It is also found in many other parts of the world, including north and central America, much of Europe, and across Asia to Japan. It prefers coniferous forests, at all altitudes, but is sometimes found in mixed or deciduous woodland.

A related, and very similar, species is the short-toed treecreeper (Certhia brachydactyla) that breeds in the Channel Islands but only visits the rest of the UK as a vagrant.


Appearance

The treecreeper measures about 12-13 centimetres (5 inches) in length. It has quite a long bill for a small bird, being thin, pointed and curved downwards. The head and upperparts are brown, streaked with white, with a reddish-brown rump. The underparts are white, but often appear brownish, due to the bird’s habit of rubbing against tree bark. The treecreeper has quite a long tail, stiff and pointed, which it uses as a prop when climbing trees.


Behaviour

The treecreeper has a high trill similar to that of the blue tit, and a song of descending notes.

Unlike the nuthatch and woodpecker, the treecreeper climbs trees in a systematic fashion, travelling upwards and around the trunk in a spiral, with its feet apart. It never moves down a tree. When it has gone as high as it wishes it flies down to the base of a neighbouring tree and starts again. It may also progress along the underside of branches.

What the treecreeper is doing is searching for insects, as well as their eggs, larvae and pupae, plus spiders, hidden in the tree bark. Treecreepers will also eat seeds in winter.


Breeding

A nest is built behind bark or ivy, or in any suitable crevice, and consists of woven dry grass, roots and moss on a base of small twigs, lined with a thick layer of feathers and hair. Five to seven eggs are laid, which the female treecreeper incubates for up to 15 days. Both parents feed the nestlings, on insects, larvae and spiders, for around 15-16 days, after which the young birds leave the nest but continue to be fed by their parents for a short while longer. A second brood is often raised in June.

The young birds will roam the neighbourhood and raise their own families the following year, not far from where they were raised themselves.

In winter, treecreepers may join flocks of other small birds such as tits.

© John Welford