I hit a deer on a highway once. There was a state trooper parked along the road a short distance up, so we reported it, but the ins company didn't ask for a copy of the report (the adjuster could see deer hairs stuck in the damaged part, so that was good enough for him).
The state trooper went back to the scene to find the deer, but it had run off, which is pretty amazing considering I hit it at 65 mph and it bounced from the front of the car along the side, denting it in several places. There wasn't much traffic, it was after 1 AM, so I don't think anyone else had come along and picked it up.