We evaluated how American badgers (Taxidea taxus) might exert selective pressure on black-footed ferrets (Mustela nigripes) to develop antipredator defenses. In a colony of black-tailed prairie dogs (Cynomys ludovicianus) in South Dakota, badgers concentrated their activities where burrow openings and prairie dogs were abundant, a selective behavior that was exhibited by ferrets in the same colony. Badgers excavated burrows more often when in areas recently used by a ferret, suggesting that badgers hunt ferrets or steal prey from ferrets, or both. We also conducted an analysis of survival studies for ferrets and Siberian polecats (M. eversmanii) released onto prairie dog colonies. This polecat is the ferret's ecological equivalent but evolved without a digging predator. Badgers accounted for 30.0% of predation on polecats and 5.5% of predation on ferrets. In contrast, both polecats and ferrets have evolutionary experience with canids, providing a plausible explanation for the similar relative impact of coyotes (Canis latrans) on them (65.0% and 67.1% of predation, respectively). We hypothesize that ferrets and badgers coexist because ferrets are superior at exploitation competition and are efficient at avoiding badgers, and badgers are superior at interference competition.