The red-footed falcon (Falco vespertinus), formerly the western red-footed falcon, is a bird of prey. It belongs to the family Falconidae, the falcons. This bird is found in eastern Europe and Asia although its numbers are dwindling rapidly due to habitat loss and hunting. It is migratory, wintering in Africa. It is a regular wanderer to western Europe, and in August 2004 a red-footed falcon was found in North America for the first time on the island of Martha's Vineyard, Massachusetts. The Amur falcon was formerly included herein as a subspecies but it is nowadays considered distinct. Nonetheless, it is the present species' closest relative; their relationship to other falcons is more enigmatic. They appear morphologically somewhat intermediate between kestrels and hobbies and DNA sequence data has been unable to further resolve this question, mainly due to lack of comprehensive sampling. They might be closer to the merlin than to most other living falcons, or more generally related to this species and American falcons such as the American kestrel and the aplomado falcon. The genus name Falco is from Late Latin falx, falcis, a sickle, referencing the claws of the bird. The species name vespertinus is Latin for "of evening" from vesper, "evening". It is a medium-small, long-winged species. The adult male is all blue-grey, except for his red undertail and legs; its underwings are uniformly grey. The female has a grey back and wings, orange head and underparts, and a white face with black eye stripe and moustaches. Young birds are brown above and buff below with dark streaks, and a face pattern like the female. Red-footed falcons are in length with a wingspan of . The average mass is . The main areas of European distribution are in southern Russia and Ukraine. The species occurs in large numbers in Hungary, Romania and Serbia. Smaller populations exist in Italy, Bulgaria and Moldova, in Austria, Slovakia and in Belarus. The red-footed falcon also breeds irregularly in the Czech Republic and in the Baltic States, occasionally also in Germany.