We gets rats on the farm - its a fact of life with all the animal feed and grain around.
We use rat blocks and they are put in secure bait boxes (a bit like drainpipes) so that only the rats can reach them. You don't usually see corpses lying around, I understand they die in the nests (often in drains - the smellier the better) and predators don't usually eat them. Most predators, especially cats, don't like carrion or already dead food - but it does worry me that some other animal may catch a drowsy rat and ingest the poison too.
Your rat will take a solid block back to the nest, and will come back on several consecutive days later and take additional blocks away too, so you have to keep 'feeding' them. Three or four blocks are needed to kill a full grown rat.
I really hate using poison - but traps can also catch other animals, cats, dogs, foxes, hedgehogs and birds. What's the answer (please don't say trap them and release them into the countryside - we don't want them either!)
Has anyone an alternative? Live with them?
Send for the Pied Piper?