I struggle with voles and prairie dogs, they dig into the coop, eat the chicken feed. I try and remove the feed at night to at least eliminate that temptation and hope the chickens will eat them or scare them off during the day. I eventually brought home a free cat from craigslist who manages to catch one just about every time he goes outside. I know this might not be the answer you are looking for, but my mouser has proven to be a good investment. We were skeptical at first, but didn't know what else to do. I am following this thread because come spring I'm sure we'll have a whole new crop of critters to contend with and I doubt the cat will completely keep up.