Predation affects the demography and population dynamics of prey species. Because predators commonly stalk prey from concealed routes, attack quickly, and frequently avoid areas with human observers, documenting predation under natural conditions is often difficult. An adult female American badger (Taxidea taxus) with offspring moved into a colony of Gunnison's prairie dogs (Cynomys gunnisoni) living under natural conditions at Valles Caldera National Preserve in New Mexico, United States, and provided an excellent opportunity to record predations over a period of 33 consecutive days in June–July 2018. Badgers are commonly nocturnal, but the badger at our study area captured a total of 100 Gunnison's prairie dogs during daylight hours. Sixty-two of the victims were adults (≥1 year old), 32 were juveniles (≤3 months since birth), and 6 were of unknown age. Most predations occurred in mid-morning and early afternoon. Our results, which do not account for nighttime predations and therefore underestimate numbers of successful attacks, suggest that a single predatory individual can have a sudden, devastating effect on a prey species.