What are bird boots?
Raptors, such as eagles, hawks, vultures, owls, and falcons have boots.
Boots are the heavily feathered thighs of raptors. Thighs are the top parts of the legs.

African White-Backed Vulture with white boots
Photographer: Martina Nicolls
Martina Nicolls: SIMILAR BUT DIFFERENT IN THE ANIMAL KINGDOM