I'm putting my money on owls, they won't eat the body of larger animals for some reason. I have ducks and I used to keep rabbits, both in pens without rooves (roofs, whatever, it didn't have a top), about ever other night one of either animals would be dead without a head. I put chicken wire over the top, but left it so something could fall in if they landed on it, then not get out, I caught 5 owls in a week before they stopped showing up. I know I'm going to catch heck for killing owls, but it was perfectly legal, they were caught in the act of harming livestock, it was my right to destroy them.