My backyard set up is a solid wood walled coop, raised off the ground, with a small door to an attached and fully enclosed run. The run has a door that leads to a fenced off area with an open top that I let the chickens use during the day. At night I close the run door but leave the coop door open. The run is pretty tight and no predators have even tried to get in yet (we have cats, possum, and raccoon's). This morning I went out to open the run door to the outer fenced area and saw that we had left that door open, so anything that jumped the fence could get into the coop at night. I was relieved to see 3 of our 4 chickens roaming outside and hoped to see the 4th in the nest box. Instead I found her dead on the coop floor, covered in ants. My first assumption was a predator got her in the night. But when I removed her I could see no blood or injuries anywhere. She looked totally intact, and the other hens seem totally un harmed as well. Is this just a coincidence? Or would a raccoon or possum be able to kill the hen and leave no marks, make no attempt to eat her, plus not harm any other chickens?