I have an enclosed pen, wire nailed to posts buried a foot underground, walls are about six feet high and deer netting over the top. Last night something went through the top of the pen, killed all 12 of my chickens. None were missing or eaten. They were all attacked on their heads and necks. It's like something came in through the netting six feet off the ground massacred all 12 then left back out the netting on top.Just killing for the fun of it. Any ideas on what it could have been?