Rodents will take up residence under the floor foundation of a hen house. Raccoons will take up residence in the attic. I do battle with the raccoons and kill them (hens will eat it).
The rodents become barn cat business. Feed the cats at the outside floor of the hen house. If they perceive the rodents as a threat to their food dish, they will kill them all.
The building was a remnant from a mink farm. This guy was overfed, as was his cat, and all of the other animals. I’d have thought he would invest in a BB gun, just for the entertainment. A couple of drowning traps could have cut the population pretty quickly. Too much like effort, I guess.