After decades of keeping poultry, feeding wild birds and owning cats we never saw a rat until last year even though close to the canal and river. This year brought a plague of the beggars. I'll be honest, it was freaking me out. Daytime was not a problem for them, even standing up at my back door. Aaaaaaaagh!
We have moved the bird feeder, cut back fruit bushes, put down citrus bleach, coffee grounds, hot chilli powder, and highly successfully, but surprisingly, talcum powder. 5 traps and a plug in sonic deterrent seems to have won the war. We were getting a real bunch of the little pests and I won't use poison, but they do like peanut butter or chocolate spread. Keeping my fingers crossed that's it but shan't be complacent. Best of luck out there.