Having a similar problem here too with regards to predators. Something is snatching the chickens during the day and killing them here. I have some young ones, maybe 8 weeks old or so. It's killed a couple of those, plucked and ate them entirely in the yard. I know this because I've found a single pile of feathers which appears to be nearly every feather on it's body and today I found a small piece of what appears to be spine in the pile of feathers. Another young chicken it ate it in the bushes next to the coop. Same thing, except I didn't find a piece of bone left behind. I didn't really look much either. Just found a large pile of feathers where it clearly killed and ate the chicken.
Now, I'm also lost a few adult hens to this predator as well. Their's is a much larger struggle. Usually starts at one end of the yard and ends at another. With two of the hens, I didn't find the carcass. Just large piles of feathers scattered in the yard. I lost a rooster a couple months back too. He was a very large bird and again.. same method of operation, struggle started at one end of the yard and ended at another, except I actually found half of his body in the woods. Just the lower half. Again.. he was a very large bird and would've been hard to carry off.
My guesses at this point.. fox or raccoon. I've got a live trap set with chickens remains in it and something has gotten in the trap and managed to get back out. This leads me to believe a fox.. because the trap door may have landed on the fox and he was able to quickly back out before the door fully closed and latched. It hasn't gone for the trap since that happened.
One more thing to note, I believe these attacks are happening either during the day or at dusk, just before I go out to lock them up. I thought a couple times that maybe those hens just didn't go back to the coop at night and were thus left outside to the predators when I locked everyone else up.. but I'm not believing that to be the case anymore. I see no reason that the younger chickens would separate from each other like that, especially at bed time.
As far as your chickens not going back to the coop, you should keep them locked in the coop for AT LEAST 48 hours so they learn that this is home and where they live. They should get the point and start coming back on their own.. but being that you free range them, you ARE going to lose chickens to predators. Regardless of whether they are the weakest genetic link or not. I've lost nearly 30 in the past two years and they ONLY get taken when they are free ranging. I use Premier 1 electric poultry netting otherwise but I stubbornly still insist that they be allowed out to free range. Some of my hens are 4+ years old and the ones I've lost were primarily young pullets. 8 of them in a single night last year.
Anyway, hope this helps. Again.. I'm thinking fox or raccoon. I've trapped and/or seen both around here. Just wish I could figure out which one uses this method of operation so I can narrow down how to trap this thing.
