Certhiidae – Treecreepers
The treecreeper, Certhiidae are a family, of small passerine birds, widespread in wooded regions of the Northern Hemisphere and sub-Saharan Africa. The family contains just 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.
Most species of treecreeper occur in the Palearctic and Indomalaya ecozones, from Western Europe to Japan and India. One species occurs in North America from Alaska to Nicaragua and another has a discontinuous distribution in sub-Saharan Africa and India. All species of treecreeper are found in forest and woodland habitats. The more northerly species are partly migratory, and those found in warmer climates are thought to be resident, although information is lacking for many species.
They 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.
Treecreepers are generally unobtrusive and are often indifferent to humans. They occur as singles or in pairs, sometimes in small family groups after fledging. Occasionally they will flock with other passerines in winter to forage. Communal roosting has been observed in three species (and may occur in more), with as many as 20 birds sharing a roosting hole in order to conserve warmth.
They forage on the trunks of large trees, moving up the trunk in a progression of small hops. They then fly to the bottom of another tree, climbing it in a spiral fashion searching for prey. The majority of their diet is composed of small invertebrates, including insects and their larvae, spiders, and pseudoscorpions. In hard times seeds and fruits may be taken, and a few species will also visit birdfeeders.
The Certhiidae are monogamous and territorial. Nests and eggs vary between the genera. The Certhia treecreepers usually nest in a gap between the tree bark and the tree, whereas the nest of the spotted creeper is placed in the fork of a branch. Incubation lasts 14 to 15 days, and young fledge after 15 to 16 days.
According to the IOC there are just eleven species of Creeper, which are:
Eurasian Treecreeper Certhia familiaris
Hodgson’s Treecreeper Certhia hodgsoni
Brown Creeper Certhia americana
Short-toed Treecreeper Certhia brachydactyla
Bar-tailed Treecreeper Certhia himalayana
Rusty-flanked Treecreeper Certhia nipalensis
Sikkim Treecreeper Certhia discolor
Hume’s Treecreeper Certhia manipurensis
Sichuan Treecreeper Certhia tianquanensis
Indian Spotted Creeper Salpornis spilonota
African Spotted Creeper Salpornis salvadori
Number of bird species: 11