Facultative zygodactyly in the Black-shouldered Kite Elanus axillaris

Abstract

This note describes and illustrates facultative zygodactyly in the Black-shouldered Kite Elanus axillaris, whereby the Kite is able to swivel the outer toe from the anisodactyl position. Such an ability has been little studied or commented upon; in this respect, this genus of diurnal raptors resembles ospreys Pandion spp. and owls (Strigiformes).