I found out they climb fences from a gentleman we picked up a tree from.. around his Chinese veggie garden.. he had corrugated aluminum strips like a cap on top of the fence.. I asked him why.. and he said it stops the critters from being able to climb up and over.. they climb up and hit there heads .. like a squirrel guard on a bird feeder pole...looked at him and said a GH can climb a fence???
he assured me they can do it with ease .. wish I wouldn't have felt funny to take photos of his set up .. after he gave me a tour of the garden I didn't want to push it... after we left I thought I should have asked if he had anything in the ground to stop them from digging.. too late