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.
