I have only seen a couple of deer with those holes and I have heard afew different things from people. Ive heard the bug idea,The birth defect idea,damage suffered to the head from fightingor fromsome other blunt/tear trauma, and another birth idea the fawn suffers some kind of damage while still in the womb of the pregnant doe. All of these are hear say so I dont know if any of these are correct. Im really interested in finding out myself now.