Using Drones to Train Falcons
slate.com
slate.com
The issue is about training. Pretty much all our medium and large falcons (peregrines, gyrs, hybrids) are captive bred, so humans are the only thing teaching them to fly strongly and hunt. And because we're humans, we want to train quickly so we can go hunting and nail some ducks.
Climbing to 1000', 1500' takes muscle, and all the techniques (balloon, kite, drone) give the bird motivation to get up there and build that muscle. It also trains in the habit of getting to a good height.