Hubby killed a possum in the pen a few weeks ago after it got in somehow and was eating the feed. No chickens hurt but that explained why we're going thru so much food. Monday night we installed 4 Nite Guards on the perimiter of the pen as per instructions, and we also have a trap set where the last possum got in. Last night I went out to make a final check on the birds and there was a possum up on its back feet trying to figure out what that red blinking light was!! He got away before we could get him. A bit later just was we were about to turn out lights for the night, hubby looks out and there that dang thing is again! This time SITTING IN THE FEEDER having a grand time munching away. Out we go again, hubby shoots at the possum with the .22 but it just wanders over under the coop. Hubs goes back for more fire power and this time gets the job done. All the chickens were down for the night and didn't even seem to mind all the chaos. I sure hope the Nite Guards work better on other critters because the possum didn't seem to mind them at all. Could be though that hubby installed them too high despite me saying they need to be LOWER. I hate possums! Lucky though that so far they have just been after the food and none of the chickens. They are like rats though, and can squeeze thru the littlest opening. Our pen has 2" x 4" welded wire all around and over the top and the possums still manage to wiggle thru.