Deer are nimble creatures, but even they sometimes overestimate their abilities. Experts generally agree that deer can jump about eight feet in the air, with some more impressive specimens going even higher. As acrobatic as deer may be however, a properly constructed high-fence usually means a dead end. Add that to poor depth perception, and it means that many deer are prone running face-first into a barrier.
Watch what happens when one deer meets a fence in midair.