I think it was rats, not much else it could be. I just got my chickens yesterday, 5 little brahmas. They are at least a month old, I thought they would be safe in the chicken tractor. I checked on them several times thoughout the night and they seemed fine. About 5am my doggies ran out and barked and the one pawed at the tractor. I scolded her because I thought she was trying to get the chicks or the food. I went in the pen before I was to leave for work and found a dead one with it's head eaten off. I should have known better, we have marsh rats in the area. They aren't terribly big but they are always around. I've seen them hop from my garden to a tree IN BROAD DAYLIGHT! So now I have my babies in a doggie crate in the house until they get older. I have a trap set in the run, I will continue to do this every night. I am also going to get some poison, which I really hate to do but it's impossible to control them without it. How big should my girls be before I can leave them out all night? I don't think there is any way to rat-proof my coop, I've seen these things walk right up the side of the house and through small cracks. Plus, since it's a tractor, it's portable so I can't bury wire under the ground. I figured I would have problems with coons hawks or possums. I live in a subdivision but it's near marshes and a golf course, so there are native wild animals around. I also feed birds and have a garden which probably doesn't help. The rats are there regardless though. My doggies (beagle and beagle/dachound mix) are pretty good at sniffing them out. At least I guess they are, they tell us when one is around the patio so we can eliminate them. Who knows how many sneak by them. The little chickens aren't roosting yet, they just huddle on the ground in the leaf mulch I put down for them. It was an easy meal for something. I should have known better. I have 4 left, I don't want to loose them all. I wonder if I should build a more secure night hutch for them. Surely I'm not the only one with a chicken tractor that lives near rats.