Although they are somewhat inconspicuous because of their small size, drab coloration, and tree bark-like camouflage, Brown Creepers (Certhia americana) are actually fairly common, year-round residents in wooded mountain areas here in southeastern Arizona. Because they prefer forested areas, Brown Creepers are only rare to occasionally uncommon transients and winter residents in lower elevation desert areas here with large trees. I observed this busy little Brown Creeper climbing a tree trunk in the Santa Catalina Mountains near Tucson, Arizona.
Solitary Brown Creepers are usually seen creeping in an upward spiral around tree trunks as they probe the bark for insects. Once they finish searching the bark of one tree, they will then fly to the base of another tree and begin their spiraling upward search of the bark once again. Their bark-patterned, brown plumage serves as excellent camouflage as they forage on the exposed tree trunks. Brown Creepers not only forage on tree bark, they will also generally use a flap of loose tree bark as their nest site.
Brown Creepers are a bark-like, streaked and mottled brown above and whitish below, and they have dark eyes, a white line over the eye, a slender, black, decurved bill perfect for insect probing, an often hidden, rust-colored rump, and stiff tail feathers like those of a woodpecker that they use as props to brace them as they climb. The sexes are very similar, but the males have slightly longer bills. Because of their similarity, I don't know if this solitary Brown Creeper above was a male or a female.