The long-tailed tit (Aegithalos caudatus), also named long-tailed bushtit, is a common bird found throughout Europe and the Palearctic. The genus name Aegithalos was a term used by Aristotle for some European tits, including the long-tailed tit. Taxonomy and systematics The long-tailed tit was formally described by the Swedish naturalist Carl Linnaeus in 1758 in the tenth edition of his Systema Naturae under the binomial name Parus caudatus. The specific epithet caudatus is the Latin word for "tailed". Linnaeus did not invent this Latin name. "Parus caudatus" had been used by earlier authors such as the Swiss naturalist Conrad Gessner in 1555, the Italian naturalist Ulisse Aldrovandi in 1599, and the English ornithologist Francis Willughby in 1676. Willughby listed the English name as the "long tail'd titmouse". Its previous common nickname in everyday English was the bum-towel, from the shape of its tail. The long-tailed tit was first classified as a true tit of the Parus group. Parus has since been split from the Aegithalidae, with the latter becoming a distinct family containing three genera: Aegithalos (long-tailed tits), five species including A. caudatus Psaltria (pygmy bushtit), monotypic Psaltriparus (American bushtit), monotypic. This is the only representative of the Aegithalidae in northern Eurasia. The long-tailed tit exhibits complex global variation with 17 races recognised, divisible into three groups: the A. c. caudatus group in northern Europe and Asia. A. c. caudatus has a pure white head the A. c. europaeus group in southern and western Europe, north-east China, and Japan. Separating A. c. rosaceus from other members of the A. c. europaeus group though is problematic, relying on varying thickness of the crown stripes and amount of streaks and colour on the underparts the A. c. alpinus group in Mediterranean Europe and south-west Asia. The silver-throated bushtit (Aegithalos glaucogularis) from eastern China was formerly considered conspecific but the plumage is distinctive and there are significant genetic differences. Where the groups meet there are extensive areas occupied by very variable ‘hybrids’. The British long-tailed tit, subspecies A. c. rosaceus, belongs to the A. c. europaeus group. Description This species has been described as a tiny (at only in length, including its tail), round-bodied tit with a short, stubby bill and a very long, narrow tail. The sexes look the same and young birds undergo a complete moult to adult plumage before the first winter. The plumage is mainly black and white, with