Just the other day, I caught a radio talk about rodenticides, and the negative secondary effect the poisoned animal had on other populations (inadvertently killing predators and scavengers consuming the poisoned rodent). It also rather graphically described how the rodenticides work, and none of them sounded very kind or gentle - internal bleeding, kidney failure, etc. The upshot of this particular talk was that the tried-and-true snap-traps are the most humane method, death is quick, and there are no secondary casualties. I agree with Stone that cats are a good first line of defense. In the rare times we have not had outdoor cats, we've had a noticeable influx of mice and rats. I suppose my song bird population also takes a hit, although I think field mice are easier pickings than birds.
