Yep.before the chickens I had a skunk that tried digging under--that is why the stone was put in place.
I do believe the oppossums and raccoons climb the fence and have been in the yard. They live in the trees on the other side of the privacy fence. When I put that femce up I left about 5 ft between the property lines, so I can walk through--that may have helped with the oppossum/raccoon issue. They can jump from the trees to the top of the femce. I did put a ground and hot wire on top of two sides of the run--so if they jump from privacy fence to run--they get zapped.
That's another good point about the trees. People often like to put coops under trees for protection from the elements, but it certainly can make your setup more vulnerable to predators.