Black-footed ferrets are North America's most endangered mammal and depend entirely on prairie dog colonies for food and shelter.
Black-footed ferrets in the wild face mortality from plague, predation, and insufficient prairie dog prey. Captive breeding animals experience restricted environments that cannot fully meet the behavioral needs of these active hunters. Reintroduced individuals face the stress of establishing in unfamiliar territory. Plague vaccination of prairie dogs is proving effective at protecting the prey base that ferret welfare depends on.