The brown creeper has sometimes been considered to be a subspecies of Eurasian treecreeper, but has closer affinities to short-toed treecreeper, and is normally now treated as a full species.[2] Hodgson's treecreeper is a more recent proposed split following studies of its cytochrome b mtDNA sequence and song structure that indicate that it may well be a distinct species from C. familiaris.[2]