I went out this morning an found something had dug a hole in the very dead center of my run 4ft from either side and 8ft from either end. I keep straw down on the dirt floor and it had all been pushed away from the opening. My husband let them out yesterday and so the door was open all day. The hens were all ok, so I am assuming it isn't a weasle. when I built it last spring I buried hardware cloth a foot deep and two feet out around the entire perimeter even under the door.I also covered the entire run in hardware cloth, not chicken wire. I noticed the same thing months ago outside the run. If by chance it is a rat, how will I know, and is it harmful to chickens?