I've used poison twice; once in the barn for rats, and this winter for mice in the coop. Carefully managed, no pets out loose, and the only effective method for rats especially. My latest barn cat was too afraid of the chickens to enter the coop and work on mice there, and she moved to an indoor home last fall. Without a barn cat, the mice really took over! They have been living in burrows under the broken concrete floor, and no new concrete can be poured until spring.
Mary
Mary