I don't know if anyone else has suggested this, but is it possible for you to just pour a cement floor right over the dirt? Otherwise, hardware cloth and extend it out around the coop a good 6 to 10 ft. I found something interesting that has helped me covered dig holes and openings in my chain link. It's sharp and will really hurt the paws, so nothing has gotten through. Some holes are relatively small and I just cut this stuff with a wire cutter. And thick gloves lol.