We found a raccoon in our coop this morning. It had mutilated a bird which we had to put out of its misery. I have no idea how it got in the coop. This is the third bird we've lost recently to predators. We also caught a possum in there but it didn't get any birds. I've walked around the coop and I don't know where it's getting in. How to I protect my ladies better in the future?