answered:
The title of smallest bird of prey is actually a tie.
The genus Microhierax is a whole group of falconets - teeny tiny falcons. The smallest two of those are the Black-Thighed Falconet and the White-Fronted Falconet. Both are Indomalaysian species with a wingspan of 11.5 inches (27-32cm) and a body length of 6 inches (14-17cm). That’s right - they are only a bit larger than a sparrow! Though their big, powerful little talons and hooked beak certainly sets them apart.
A black-thighed falconet:
White-fronted falconets
Thanks for the question!