This is a great method. I have been using it to control the chipmonk population around my yard ever since the suckers made a nest in my car and it cost me 2000.00 to repair. Use Black oil sunflower seeds. They are irresistable to rodents.A clever trap is a 5-gallon bucket, half full of water, then drop in enough sunflower seed to cover the water. The sunflower seeds float. Put two or three short boards leading up to the top of the bucket like ramps. Sprinkle more sunflower seeds around the area. The rat/mouse/squirrel goes up the ramp, sees the bucket full of seeds and jumps down into what he thinks is a bucket full of seed.......see how long he can tread water. They drown in less than half an hour. Safe, clean, cheap and no colateral damage as you might easily have using poison. You'll have to keep this out of reach of "the girls" or they'll probably try to jump in as well.
It will need to be freshened up every couple of days, and when you dump it out, be sure it is well away from the coop area. You do not want to attract any more pests. I use a long pair of tongs to remove the carcass. You will be amazed at how effective and quickly this method works. I removed 70 chipmonks from my yard last summer doing this. For some reason, there was an explosion in the population last year and they were beginning to get into my house as well as damaging my brand new car.
I still use this method and it is the best way to quickly remove pests.
Try it. You will see!