We had a rat in our garden earlier this year. I was horrified. We called the council in and he said, immediately, stop putting food on the ground for the birds. We have a slim pole feeder with a tray about half way up and he said that should be ok, as they were unlikely to be able to climb it. He put down to bait traps, but the bait was left untouched during the three weeks they were there. We have never seen any sign of the beast since, but it has made me very wary. We have very tidy environs so I have no idea where it could have come from or where it ultimately went to. A very expensive exercise though!