Make sure to take eggs everyday, keep everything clean and tidy. I had a problem where they would dig under the bricks of my house and enter the basement (chicken room) so we buried glass shards and added a wall of bricks to deter them. We also used pellet poison away from the chickens, I don’t recall what brand (I’ll update tonight) but within a month we didn’t have a rat problem anymore, plus the poison dehydrated them so they didn’t stink. During unfortunate occurrences when rats would run by me, they met their fate at the hands of a shovel. If you have a gun and spare time, consider what others told you and set some bait. Hell, make it fun and bring a beer or two! 
