I totally agree with KristinH. KILL IT! Last time I checked, possums were not on the endangered species list. I had the same problems with a racoon or two in the past. I tried the nice guy approach, the havahart trap, shoo-ing it away, adding extra defenses, ETC. the problem continued...until I shot it, skinned it, and nailed the hide to the side of the coop. Racoon activity dropped to 0% since then(Jun 2006). That seemed like a ringing endorsement for the .22LR to me.