I have heard that the ticks don't drop off immediately because the carcus is still warm. One tip I heard, but haven't tried, is to place a large (about 3 feet in diameter) tub partially filled with water under the deer once it is hung. The ticks can't jump, so will drop off the deer. They can't get out of the water. Without the tub they would walk away and wait for their next victim.

Hunting is a right, treat it like a priviledge - respect nature