Simplest solution for getting rid of mice - peppermint oil! The little buggers can't stand the smell. Dab some peppermint oil on cotton balls and place them strategically around. In a coop, you can punch holes in a can and place the cotton balls in the cans. You'll also have the best smelling chicken coop in the county! You can get the oil in health food stores. It's not cheap, but a little goes a long way. We had mice in the house all the time. Now I use it in the crawl space under the house and in the attic. No more mice.