The family Certhiidae, commonly known as treecreepers, is a group of small passerine birds found across Europe, Asia, and North America. These birds are characterized by their slender, down-curved bills, which they use to probe bark for insects and other invertebrates, and their stiff tail feathers that provide support as they climb tree trunks in a spiral pattern. Certhiidae species are generally cryptically colored with brown, streaked plumage that helps them blend into tree bark. They typically nest in crevices or behind bark and lay small clutches of eggs. Treecreepers are highly specialized for a foraging lifestyle on vertical surfaces, and their behaviors and morphology reflect adaptations to arboreal insectivory.