@Puppadore,
The all time favorite for Rat extermination is a CAT as in “meow”. I am 100% serious. I have never had a cat that was not an excellent hunter. I joke you not! “Whitey - short for White Sox” has No friends on our property as he eats them all. If it moves he is on it. Birds, Lizards, Moles, Gophers, Mice, Rats, Grasshopper, Etc. He simply doesn’t know any different. The little guy is determined to get a Bat that roosts above our porch. Try it! You have nothing to loose & believe it or not they are very loyal, smart and make a wonderful addition to the family.
Often times, they are so curious and dearly seek attention, you may find yourself working on a project and a little tiny paw gently touches you. That will surely put a smile on your face and make day & even warm your heart.
P.S. Whitey since day one has been an outdoor cat.