Erika calls them “Tree Lice.” Poulin et al. (2013) write that the Brown Creeper can be hard to find, despite the bird’s being common and wildly distributed across North America south to Nicaragua. Creepers feed on bark-dwelling invertebrates. The creeper begins at the base of a tree trunk, climbing with the aid of its stiff tail. Then the bird flies to the base of a nearby tree and begins its spiral climb again.
The creepers in our backwoods seem to feed on suet that other birds cache in tree trunks. They also feed on suet dropped under the bird feeders or on the ground at the base of nearby trees.