I had a drivers licence at 14 , so I suppose, wether or not I WOULD allow a child to hunt alone at 13 would have to be determined on each child individually. some 13 year olds are more mature and gun safe then, adults that are 40.if child has been taught well , he should be fine to hunt on own.
I would however insist on knowing where he was hunting and set a time on when he should be home. and I would have him carry a phone just in case he had trouble and needed help