Black-footed ferret  (Mustela nigripes)

The number of black-footed ferrets plummeted in the first half of the 20th century, primarily as a result of habitat loss. Prairies have been modified for intensive agriculture and there is now less than two percent of the original ferret habitat left (3). The ferret's main prey, prairie dogs, were systematically poisoned in vast tracts of their habitat by a government eradication programme in the mid 1900s (5). Prairie dog burrows were thought to damage cropland and ferret numbers fell in direct proportion with the dramatic decline of their prey (3). The final threat to black-footed ferret numbers, and perhaps the most pertinent today, is disease, particularly canine distemper and plague (3). Plague, introduced to North America, causes even greater devastation in populations of prairie dogs and ferrets than it caused in human populations of Europe and Asia (8).

The black-footed ferret was thought to be extinct in the 1970s until a last population was discovered in Meeteetse, Wyoming in 1981 (5). Under initial protection measures, this population increased in numbers but then became infected by canine distemper and plague, which threatened to completely wipe out the species (5). As a last resort, the final 18 wild animals were caught and brought into captivity between 1985 and 1987, and a successful captive-breeding programme has been running ever since (3) (8). The US Fish and Wildlife Service's revised 'Black-Footed Ferret Recovery Plan' of 1988 prescribed the long-term target of establishing ten or more separate, self-sustaining wild populations, aiming to have 1,500 ferrets in the wild by 2010 (9). As of 2008, populations had been reintroduced to 18 sites, and with up to 250 wild born individuals distributed amongst several of these populations, the black-footed ferret was reclassified by the IUCN, moving from Extinct in the Wild to Endangered (1). While this is a fantastic conservation success story, wild ferret populations remain small (1), and conservation will need to continue if this species’ future is to be secured.