Thetreecreepers are afamily,Certhiidae, of smallpasserinebirds, widespread in wooded regions of theNorthern Hemisphere. The family contains nine species in onegenus,Certhia. Their plumage is dull-coloured. As their name implies, they climb over the vertical surfaces of trees in search of food.
Some taxonomists place thenuthatches and treecreepers in a larger grouping with thewrens andgnatcatchers. Thissuperfamily, the Certhioidea, was based onphylogenetic studies usingmitochondrial andnuclear DNA, and was created to cover a clade of four families removed from a larger grouping of passerine birds, theSylvioidea.[1] The fossil record for this group appears to be restricted to a foot bone of an earlyMiocene bird fromBavaria which has been identified as an extinct representative of the climbingCerthioidea, aclade comprising the treecreepers, wallcreeper and nuthatches. It has been described asCerthiops rummeli.[2]
Thewallcreeper was originally described in the family Certhiidae but is now considered as more closely related to thenuthatches. Thewoodcreepers (subfamily Dendrocolaptinae) also have a similar name.
An extinct treecreeper,Certhia rummeli, was described from a fossilized righttarsometatarsus found in karstic fissure fillings in Petersbuch,Bavaria by German paleornithologistAlbrecht Manegold. This specimen implies the branching of Certhioidea occurred 20 MYA, and represents the oldest fossil passerine assignable to an extantsubordinated clade ofoscines in the Northern Hemisphere.[6]
Treecreepers measure from 12 to 18 centimetres (4.7 to 7.1 in) 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 ahelical path, hopping with their feet together; their toes are long and tipped with strongly curved claws for gripping. The longer tails of theCerthia 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.[7]
Most species of treecreeper occur in thePalearctic andIndomalayan realms, from Western Europe toJapan andIndia. One species occurs inNorth America fromAlaska toNicaragua. 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.[8]
Treecreepers are generally unobtrusive and are often indifferent to humans. They occur as singles or in pairs, sometimes in small family groups after fledging.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.[8]
Treecreepers forage on the trunks of large trees. They move up the trunk in a progression of small hops. They fly to the bottom of a tree, then climb in a spiral fashion searching for prey. The majority of their diet is composed of small invertebrates, including insects and their larvae, spiders, spider eggs, and pseudoscorpions. In hard times seeds and fruits may be taken, and a few species will also visit birdfeeders. Species in both genera have been recorded joiningmixed-species feeding flocks.[8]
The treecreepers aremonogamous andterritorial. Nests and eggs vary between the creepers: theCerthia 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.[8] Incubation lasts 14 to 15 days, and young fledge after 15 to 16 days.[7]
^Cracraft, J.; Barker, F. Keith; Braun, M. J.; Harshman, J.; Dyke, G.; Feinstein, J.; Stanley, S.; Cibois, A.; Schikler, P.; Beresford, P.; García-Moreno, J.; Sorenson, M. D.; Yuri, T.; Mindell. D. P. (2004) "Phylogenetic relationships among modern birds (Neornithes): Toward an avian tree of life." p468–489 inAssembling the tree of life (J. Cracraft and M. J. Donoghue, eds.). Oxford University Press, New York.ISBN0-19-517234-5
^Manegold, Albrecht (April 2008). "Earliest fossil record of the Certhioidea (treecreepers and allies) from the early Miocene of Germany".Journal of Ornithology.149 (2):223–228.doi:10.1007/s10336-007-0263-9.S2CID11900733.
^abcdHarrap, Simon (2008). "Family Certhiidae (Treecreepers)". In Josep, del Hoyo; Andrew, Elliott; David, Christie (eds.).Handbook of the Birds of the World. Volume 13, Penduline-tits to Shrikes. Barcelona: Lynx Edicions. pp. 166–179.ISBN978-84-96553-45-3.
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