Certhiidae Treecreepers
Version: 1.0 — Published March 4, 2020
Introduction
Treecreepers “creep” up forest tree trunks with a series of mouse-like small hops, spiraling up around the trunk in search of small arthropods, which they glean from crevices in bark and branches with their fine, slightly decurved bills. Like other tree-climbing birds, treecreepers possess stiffened tail feathers for support on tree trunks. Their brown-toned plumages with contrasting streaks and spots make these diminutive birds hard to see from afar, and their high sibilant calls are difficult to localize. Spending all their lives on tree trunks and large branches, certhiids even place their nests beneath a flap of loose bark. Most diverse in the mountains of Asia, these forest birds are widespread throughout the forests of the north temperate zone.
Habitat
The treecreepers live in forests and woodland, where they forage almost exclusively on the trunks and larger branches of trees.
Diet and Foraging
Certhiids are primarily insectivorous, taking a wide assortment of small insects and spiders. Most food is obtained by gleaning and probing bark crevices on trees, very occasionally by sallying or hover-gleaning. When insects are scarce, treecreepers will eat seeds.
Breeding
Treecreepers are monogamous with biparental care. The typical nest site for treecreepers is the gap between a large, loosely hanging chunk of bark and the trunk of a tree. If such sites are not available, they will use a knothole or abandoned woodpecker nest-hole. In this shelter, they build a base of bark and twigs, with an inner cup of finer material such as grass, moss, spiderwebs, lichens, feathers, and wood fibers. Female treecreepers generally lay 3 to 6 eggs. Both sexes are active in nest construction, though only the female incubates. The male feeds the female while she incubates, and both male and female feed the chicks. Incubation takes about 15 days, and the young fledge after two to three weeks in the nest. The fledglings are fed by the parents for up to 17 days or so after they leave the nest.
Conservation Status
Forest birds everywhere are facing pressure from the conversion of forest habitats, but only one treecreeper species (11%) has a small enough range that the conversion of its temperate forest habitat has caused conservation concerns (1 NT). The Sichuan Treecreeper Certhia tianquanensis is limited to very few forest patches in the mountains of Sichuan, China, where development and disturbance are pressing concerns.
Systematics History
The treecreepers are part of the superfamily Certhioidea of oscine passerines (Alström et al. 2013a, Alström et al. 2014, Cracraft 2014). Certhiidae has long been thought to be sister to Sittidae, a sister relationship that is supported by some recent molecular phylogenetic evidence (Barker et al. 2004, Reddy & Cracraft 2007). Alternatively, Certhiidae may be sister to the clade made up of Polioptilidae plus Troglodytidae (Barker 2004, Zuccon et al. 2006), or, perhaps most likely of all, sister to the rest of Certhioidea (Johansson et al. 2008b, Alström et al. 2013a).
Conservation Status
Least Concern |
100%
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Near Threatened |
0%
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Vulnerable |
0%
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Endangered |
0%
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Critically Endangered |
0%
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Extinct in the Wild |
0%
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Extinct |
0%
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Not Evaluated |
0%
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Data Deficient |
0%
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Unknown |
0%
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Data provided by IUCN (2023) Red List. More information