Falcons hunt by scanning the ground in a cone below them. The size of the cone depends on just how high above the ground the falcon's eyes are. On their own, the birds aren't always inclined to fly high while looking low. For centuries, falconers have trained falcons to fly higher and higher, expanding the area they can search. Traditionally, this is done with a lure slung on a line beneath a kite or a balloon. The falcon grabs the lure and returns it to its trainer for a reward. Over time, the falcon learns to fly high and hunt prey over a larger area.