Jim Dandy: He/she/they must've had a direct-route to the great outdoors last winter.....they'd only be heard when the temps dropped way low (or we got a good bit of snow).....and they definately got out, the maintenance guys (I rent) cleaned out my exhaust fans earlier this summer and I asked em to check.....they didn't find anybody But I've also learned not to leave any food (including pet food) out at night, especially after my "mouse encampment" experience