We (my Brothers and I) got into a discussion a few days ago about the effects of rats on farm buildings. We don't have trouble with mice or rats around our home farmstead because of the 30 or more cats we feed out by the barns. I do have 3 remote sites, one with a machine shed, that have rat problems. I have spent a small fortune buying different kinds of baits in an effort to plan their demise.
Rats are hard to kill with bait because when the first rat dies from the poison, the entire colony quits eating whatever it is that they've been eating. And I mean they quit eating it forever. That's why rat killing formula's are slow acting in an attempt to get them all to eat before they learn about the problem.
That's why I said to my Brothers, "Rat's are smarter than people, when rats figure out that what they are eating is killing them, they stop eating it."
I was going to give you an analogy here but I don't have time, I need to go fry a Twinkie for breakfast.