I was awakened at 2:30 am with my chickens freaking out. I ran out to the pen and found 5 of my 6 chickens on the roost freaking out. One chicken was in the nesting box dead. I could not find any blood or feathers torn out. I usually leave the hatch door open so the chickens can go in and out freely. I have a big dog fence that surrounds my coop. I know something had to have gotten to the chickens but I was wondering if anyone knows what it could be since it did not destroy or cut off the head.