calls. The Eurasian treecreeper belongs to the northern group, along with the North American brown creeper, C. americana, the short-toed treecreeper, C. brachydactyla, of western Eurasia, and, if it is considered a separate species, Hodgson's treecreeper, C. hodgsoni, from the southern rim of the Himalayas. 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. 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. There are nine to twelve subspecies of Eurasian treecreeper, depending on the taxonomic view taken, which are all very similar and often interbreed in areas where their ranges overlap. There is a general cline in appearance from west to east across Eurasia, with subspecies becoming greyer above and whiter below, but this trend reverses east of the Amur River. The currently recognised subspecies are as follows: Distribution and habitat The Eurasian treecreeper is the most widespread member of its genus, breeding in temperate woodlands across the Palearctic from Ireland to Japan. It prefers mature trees, and in most of Europe, where it shares its range with short-toed treecreeper, it tends to be found mainly in coniferous forest, especially spruce and fir. However, where it is the only treecreeper, as in European Russia, or the British Isles, it frequents broadleaved or mixed woodland in preference to conifers. It is also found in parks and large gardens. The Eurasian treecreeper breeds down to sea level in the north of its range, but tends to be a highland species further south. In the Pyrenees it breeds above , in China from and in southern Japan from . The breeding areas have July isotherms between 14–16 °C and and 72–73 °F). The Eurasian treecreeper is non-migratory in the milder west and south of its breeding range, but some northern birds move south in winter, and individuals breeding on mountains may descend to a lower altitude in winter. Winter movements and post-breeding dispersal may lead to vagrancy outside the normal range. Wintering migrants of the Asian subspecies have been recorded in South Korea and China, and the nominate form has been recorded west of its breeding range as far as Orkney, Scotland. The Eurasian treecreeper has also occurred