I would rather take the chance of a poisoned predator than the diseases that the rats carry. We poison the ones I can't catch and I do not lose a seconds sleep over it. I have had success with live traps for rats.... use a larger size, like for a raccoon... and different companies make them with different size wire so they are pretty tight.... opening only on one end. Then shoot them in the trap and get rid of them. Watch out for fleas and such off the rats.... even though we do not have bubonic plague, they carry many other diseases.... and fleas are common...