Yeah, I learned the hard way when I first got chickens. After a hard rain for a couple of days, Im sure it was a fox that dug under my covered coop and took off with one of my BA's. It was the only spot I didnt have wood or something covering the ground on the outside. I made sure after that it would be harder to get in. Now I have a couple of 16 ft cattle panels covered with welded wire and two 4 x 4 x 6 chain link panels making a bigger run area for them but they are locked up every night. Couple of times I think, maybe I wont tonight, but then I think, this would be the night I lose them all if I dont. Sure enough, got a pic proving that might of been the case.
Rammy