Eurasian nuthatch
The Eurasian nuthatch ("Sitta europaea") is a small passerine bird found throughout temperate Asia and in Europe. There are more than 20 subspecies, but the precise number depends on how small differences between populations are evaluated. This article follows the 2013 "Handbook of the Birds of the World Alive" treatment, which has more recognised forms than the 1996 "Tits, Nuthatches and Treecreepers". Given the similarities between geographical forms of the Eurasian nuthatch, subspecies boundaries are somewhat fluid, although fewer than half as many are recognised now as in 1967.