The symposium in context
The black-footed ferret (Mustela nigripes) is a member of the weasel family (Mustelidae) and is closely related to the Siberian polecat (M. eversmannii) of Asian steppes and the European polecat (M. putorius). Compared to its relatives, the black-footed ferret is an extreme specialist, depending on the prairie dogs (Cynomys spp.) of North American grasslands for food and using prairie dog burrows for shelter. The black-footed ferret’s close association with prairie dogs was an important factor in its decline. Prairie dogs were regarded as an agricultural pest as human settlement progressed westward, and they became important hosts for plague as that disease colonized eastward from its sources of introduction on the west coast. Prairie dog numbers were dramatically reduced by poisoning, cropland conversions, and plague during the first half of the 20th century, and black-footed ferret populations declined precipitously. The black-footed ferret was included on the first lists of endangered species, and its status was precarious by the time the Endangered Species Act of 1973 was passed. Its rebound from a low point of 10 known individuals in spring of 1985 (Biggins and others, 2006) is impressive, but the species is not yet “recovered” in either the biological or legal sense (for further details, see Lockhart and others, this volume).