What is the X in X-mas?
any of a dozen species of small slender birds, with downcurved bills, that spiral up tree trunks in search of insects. They are variously classified in the families Certhiidae and Climacteridae.
any of various small birds that hug tree trunks or rock surfaces as they move about while feeding. The following are songbirds (suborder Passeres; order Passeriformes):