I have 3 coops, 1 has an automatic door, and two do not. I also have two Cayuga ducks who USUALLY go to bed in the coop with the automatic door. Sometimes they don't make it, and will spend the night in the bottom pen area of the A-Frame "tractor" coop. One hen sleeps upstairs in it. A couple nights ago, the ducks were swimming in their pool at dusk, missing the auto-door closing deadline. I closed up the "teen quarters" coop, counted heads in the Big Coop, and checked the A-Frame for the one hen who sleeps there, but I did NOT close the door to the downstairs pen for that coop. Thought I'd wait out the ducks.... 90 minutes later, the ducks still weren't ready to go to bed. So I decided to close up the A-Frame and they could go sleep under the duck house they have NEVER slept IN. (Darn ducks.) Routine check on the lone hen, I lifted the hatch and a SMALL OPOSSUM dashed out. Scared the heck out of me. Hen was fine. I'm locking that coop up at the same time as the others from now on. If the ducks are still out in the run, they will have to sleep in or under their duck house. I don't want any critters getting comfy in my coops other than MY fowl. And in a week, the "duck house" will become the newest "baby quarters" for four more feathered out chicks. I'll be locking IT up at night, with hinges and a latch added to a board to make a door. With a screw-type carabiner lock.