The Black-footed Ferret, Mustela nigripes, has lived on the great plains of North America for millions of years. It relies on the prairie dog for food as well as shelter, taking prairie dog burrows as homes.
During the first half of the 20th century, misguided predator control campaigns and efforts to eradicate prairie dogs from farm and ranch land decimated the population. By 1967, the Black-footed Ferret joined the U.S. Endangered Species List, where it has remained ever since. In 1979 the last known Black-footed Ferrets died in Mellette County, South Dakota. The species was thought to be extinct until 1981, when a rancher’s dog dropped the body of a Black-footed Ferret on the porch of his Meeteetse, Wyoming home.
That last population of ferrets in Meeteetse Wyoming was seemingly stable, numbering more than 100 ferrets. But, as a precautionary measure, a captive breeding program was launched to establish a back-up population to safe-guard the species’ survival. Shortly thereafter, the species’ survival was put to the test; a Sylvatic Plague epidemic swept through the local prairie dog population in 1985, infecting the population. With disease threatening the survival of the last few ferrets, as many as could be captured were brought into captivity. The Wyoming State Game and Fish Department and U.S. Fish and Wildlife Service elicited the help of Association of Zoos and Aquariums specialists to save the species from extinction. A Species Survival Plan (SSP) was developed for the ferret, a living document designed to outline and assess recovery strategies and goals for the ferret.
From 1985 to 1987, the last wild ferrets were captured to begin the breeding program run by what is now called the Black-footed Ferret Recovery Implementation Team (Recovery Team). A total of 26 ferrets were captured during this period, with 18 breeding successfully, representing the genetics of just 7 founders. The first captive born ferrets were released to the wild in 1991 at Shirley Basin, Wyoming. The following year, the Recovery Team reached a pivotal milestone: a litter of kits was born in the wild at Shirley Basin. The Shirley Basin population has now become a stable recovery population.
When the captive breeding program first began, the Recovery Team had the foresight to bank cell lines, semen, and ovaries for future use. Semen samples banked between ten and twenty years ago have since been used to fertilize females, producing Black-footed Ferret kits that partially restored lost genetic diversity to the population. Revive & Restore’s 2014 study of Black-footed Ferret genomics determined that kits born via artificial insemination and advanced reproductive techniques was as diverse as a ferret born in the wild and captured for the captive breeding program in the 1980s.
To date, participating breeding centers have bred over 9,000 offspring, maintaining a captive population of approximately 400 breeding adults. From this captive breeding population, the Recovery Team has reintroduced ferrets to over 20 locations in the United States, Canada, and Mexico, increasing wild numbers to approximately 300 ferrets in recent years. This represents a major success for the Recovery Team, which is working toward a goal of 3,000 wild ferrets. Once the wild population reaches that size, the Black-footed Ferret will be downlisted from endangered to threatened. The ultimate goal is removing the species from the endangered species list to join the American Alligator and Bald Eagle as a conservation success.
Reaching recovery for the Black-footed Ferret will require innovative genetic rescue solutions to overcome eroding genetic diversity and Sylvatic Plague, which Revive & Restore is dedicated to exploring alongside the many partners of the Recovery Team.