The treecreepers are a family, Certhiidae, of small passerine birds, widespread in wooded regions of the Northern Hemisphere and sub-Saharan Africa. The family contains eleven species in two genera, Certhia and Salpornis. Their plumage is dull-coloured, and as their name implies, they climb over the surface of trees in search of food. Treecreepers measure from 12 to 18 centimetres in length. Their bills are gently down-curved and rather long, used for probing bark for insects and spiders. They often climb up tree trunks in a helical path, hopping with their feet together; their toes are long and tipped with strongly curved claws for gripping. The longer tails of the Certhia treecreepers are stiffened to use as a prop while climbing, but those of the spotted creeper are shorter and not stiffened. Their songs and calls are thin and high-pitched. (Source: Wikipedia.org, CC BY-SA)