Birds
Woodcreeper
Dendrocolaptidae · also called woodcreepers
A woodcreeper spirals up a rainforest tree trunk exactly the way a treecreeper works a forest tree on the other side of the world, bracing a stiff tail against the bark and probing crevices with a curved bill along the way. The two birds are not related in the slightest — they simply arrived at the same solution independently, an ocean and an entire evolutionary history apart.
Overview
Woodcreepers, family Dendrocolaptidae, are a diverse group of around 50 species found in Central and South American forest. They spiral up tree trunks probing bark, moss, and epiphytes for insects, bracing a stiff tail against the surface exactly as unrelated treecreepers and woodpeckers do.
Independent convergence, and a shared ant trick
The resemblance to Old World treecreepers is a textbook case of convergent evolution, two unrelated families solving the same problem the same way. Some woodcreeper species also follow army ant swarms, catching prey the ants flush out, a foraging trick separately evolved by several unrelated tropical birds.
Status
Least Concern collectively but decreasing for species tied to mature forest, since woodcreepers depend on the bark texture and epiphyte growth typical of older trees that deforestation removes first.
Woodcreeper: common questions
Are woodcreepers related to the treecreeper?
No, despite both climbing tree trunks in a similar spiralling pattern, using a stiff tail as a climbing brace, and probing bark for insects with a specialised bill, woodcreepers and treecreepers belong to entirely separate, unrelated bird families found on different sides of the world, and their strong resemblance is a clear example of convergent evolution rather than shared ancestry.
How is a woodcreeper's bill different from other bark-foraging birds?
Woodcreeper bill shape varies considerably across the roughly 50 species in the family, with some species having a relatively short, straight bill and others a notably long, strongly curved bill suited to probing deep into narrow bark crevices, moss, or epiphyte clumps, a level of bill diversity that reflects the different specific foraging niches occupied by different woodcreeper species within the same broad family.
Do woodcreepers ever follow army ants like antbirds do?
Yes, certain woodcreeper species do follow marching army ant swarms, taking advantage of insects and other small animals flushed out of hiding by the advancing ants, a foraging strategy also seen in various antbird species and other unrelated tropical birds, illustrating that ant-following behaviour has evolved independently in multiple different bird groups sharing the same Neotropical forest habitat.
Why do woodcreepers only climb up trees and not down?
Their stiff tail feathers function as a supporting brace pressed against the bark while climbing, a mechanism well suited to steady upward movement but not well adapted to descending head-first, so like treecreepers, woodcreepers typically fly down to the base of a different tree once they reach a suitable height rather than climbing back down the same trunk.