[fintstone]

Snakes work very well. We live in the country and used to have so many mice that I could trap two or three every day and never run out. The typical predators like bobcats, foxes, and hawks/eagles seemed pretty prevalent but just did not seem to do the job. Eventually a couple snakes (non poisonous...look like rat snakes) showed up around the house. I catch maybe one mouse a year now. We also used to have a bad problem with bats getting in my basement somehow. The snakes fixed that as well.