The black-footed ferret is entirely dependent on another keystone species, the prairie dog. A family of four ferrets eats 250 prairie dogs in a year; this requires a stable population of prairie dogs from an area of some .
the black-footed ferret is entirely dependent on another keystone species the prairie dog a family of four ferrets eats 250 prairie dogs in a year; this requires a stable population of prairie dogs from an area of some 