I have read that having lots of squirrels will keep the mice/rats from your area. It seems to be working here because we have lots of squirrels (mostly due to lots of pecans and acorns) but no mice/rat problems. If you don't want to waste too much food on the squirrels, just feed the chickens as much as they will completely consume in the morning (they can eat fast when they're hungry), and then leave their dish empty the rest of the day and then feed again sometime later in the day if you want. We've had chickens for years and each year brings it's own new set of problems. Are they worth it (I hear myself wondering a lot) but then I go outside and watch my chickens and the answer is always yes they are worth it, so pretty and fun to watch.