Possums can get in the tiniest holes so make sure the hen house is secure. This is your number one priority. The tracks in the third pic are from a fox or dog like creature. They can not retract their claws. Racoons have "thumbs" and their track is somewhat similar to possums and look like a hand print. It will be back. Secure the hen house and run if there is one and set a trap if you have access to one. I dont want to make you nervous but any animal that finds food will come back to where they found it. Had a poasum in my coop a few months ago and waited till i heard my girls making a bunch of noise at night. Good luck