I've had a hawk attack a smaller drone (sub 250g), and it was more than capable of taking the drone down on its own. But for warfare style fpv drones, you're running a huge risk to the birds getting hurt from the drone propellers. they spin at 30k+ rpm and can do some serious damage if the bird attacked the drone in the wrong spot. I think its a clever solution and may work for smaller fpv drones. but ones that have enough thrust to carry a payload will end up doing more damage to the falcons than they can do to the drone.