Wallcreeper

The wallcreeper (Tichodroma muraria) is a small passerine bird found throughout the high mountains of the Palearctic from southern Europe to central China. It is the only extant member of both the genus Tichodroma and the family Tichodromidae.

==Taxonomy and systematics== In the past, there was some disagreement among ornithologists as to where the wallcreeper belongs in the taxonomic order. Initially, Linnaeus included it in the treecreepers as Certhia muraria, and even when given a separate genus of its own, Tichodroma, by Johann Karl Wilhelm Illiger in 1811, it was long included in the treecreeper family Certhiidae. More recently, it was placed in its own monotypic family, Tichodromadidae, by Karel Voous in the influential List of Recent Holarctic Bird Species, while other authorities such as Charles Vaurie put it in a monotypic family called Tichodromadinae, as a subfamily of the nuthatch family Sittidae. In either case, it is closely related to the nuthatches; a 2016 phylogenetic study of members in the superfamily Certhioidea suggests it is a sister species to the Sittidae. At least one other species of wallcreeper is known from the fossil record, Tichodroma capeki (Late Miocene of Polgardi, Hungary).