Once again Howard E. nailed it with solid advice. Sanitation, exclusion, extermination. You can spend the rest of your life and all your savings on the latter two or save all the trouble by doing the sanitation bit.
Rodents need food, water, a place to hide. They can find the last two almost everywhere in most areas so that leaves one thing to control; access to your chicken food that you have left out as a rat buffet. Rat proof feeder does it 100% of the time if the directions are followed, even in commercial flocks where the feeders might get overwhelmed and a hopper full of smothered rats has to be dumped out the next morning. You starve a rat and they will become desperate. But in both cases that the feeders got overwhelmed the flock owner reported that the rats and mice refused to touch that feeder again even after they had chloroxed the feeder to disinfect it. One organic grower said they hit all twenty feeders one by one but never came back to try a previous feeder and at the end of they were rat free.
So you have options. Solve the problem for about $100 and I get to keep about $6.00 of that as profit after the end of the year. Or you can fight rodents from now on. And the wild birds.
This is what I use for mice and rats. I had a coop that was infested. When I started renovating it, rats poured out, all sizes of them. They were nesting in-between the inner and outer wall in that coop, between the studs. They actually chewed through a stud to get on the other side of it. Other critters can't get to the bait. The rats usually die in their tunnels.
