I also hesitate with poison, especially outdoors. I don't know if you have ever tried baiting with peanut butter, but mice and shrews at least seem to really fall for it! Hope you find a way to get that creepy rat, despite it's eluding the logic of said plot owner.I am reluctant to put down poison. None that I know of are instantaneous and foxes, stoats, weasels rely on the rats for food.