If you leave deer on the ground one will eventually get chewed on. It's not just wolves, coyote, and bear but also foxes, opossum, and skunks all will eat a free meal if they get the chance. They just won't eat as much.
Last year I arrowed a doe about an hour before dark. Waited 30 minutes to get down and check the arrow. Good blood so I backed out and took the bow back to the car and got ready for the drag. I found the deer in a thicket 40 yards from the arrow 1 hour after the shot and something had already been chewing on the rear end. It happens.
Mitch