Far better than cats, and far less destructive to the environment, are barn owls. A pair will consume, between themselves and their family of young, a thousand rodents per annum. It has made the world of difference here. Besides cats, domestic or feral, at least in this area, are quite ineffective. They are consumed by coyotes. Bobcats, if you have them perform wonderfully. A far better choice in most areas of this county (US) and indeed in many parts of the world, are barn owls. I no longer use traps or poisins. The latter just end up at the top of the food chain, usually in hawks, owls or kestrels. Make yourself a barn-owl house and discard the traps and poisins. Andrew San Diego