X2 in the difficulty getting rid of them. They are extremely leary of new food, so traps tend not to be effective, especially right away. I've tried poison, but again they won't necessarily eat it. Ultimately my barn cats were the only thing that got rid of them.
So not to brag or anything, but I definitely pinned one of those things against a metal building with a 120 hp front end loader and the only damage I did was pop the wheels off. Just saying...