It does sound like a possum. There are devices you can buy that are designed to repel predators, nite guard is one of them. There are mixed reviews on whether they really work, in my opinion they do. They only work at night, are solar powered, and send a red flash of light that repels night animals. I started using them about 4 yrs. ago, I had a pen of 40 or so young pullets coming up and something was getting in and taking 3 or 4 every night. I ordered these and put them up and it stopped instantly. I completely surround all my coops with them and occasionally move them around. I probably have over 500 birds right now and I have only lost one in the past year, a young roo that was in a small coop and not really that secure and not protected buy the nite guards, a possum got him and I got the possum the next night in a live trap. I have heard people say they don't work, but like I said I believe they do. They are running a special on them right now (I got a card in the mail yesterday) order 4 light get one free- Use coupon code free12. www.NiteGuard.com