Certhia

Certhia is a genus of small passerine birds in the family Certhiidae, commonly known as treecreepers. The genus includes two species, the Eurasian treecreeper (Certhia familiaris) and the Asian treecreeper (Certhia hodgsoni). These birds are known for their unique ability to climb up and down trees using their sharp claws and stiff tail feathers, which act as a counterbalance.

Eurasian treecreepers are found in Europe, Asia, and North Africa, while Asian treecreepers are native to the Himalayas and Southeast Asia. Both species are resident breeders, nesting in tree cavities or holes in the bark. They feed on insects, which they catch by gleaning from the bark and leaves of trees.

Treecreepers are small birds, typically measuring around 12-13 centimeters in length. They have a slender body, a short tail, and a long, pointed bill. Their plumage is usually a mix of brown, gray, and white, with a distinctive white rump and tail. Both sexes are similar in appearance, but young birds have a more dull plumage.

The genus Certhia was introduced by the French naturalist René-Primevère Lesson in 1831. The name is derived from the Greek word "kerthios," which means "tree-climber." The family Certhiidae, which includes the treecreepers, is one of the smallest families of passerine birds, with only two genera and four species.