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 for shelter, reclaiming prairie dog burrows as their own. During the first half of the 20th century, misguided predator control campaigns and efforts to eradicate the prairie dog from farms and ranches decimated the BFF population. By 1967, the BFF joined the U.S. Endangered Species List, where it has remained ever since. In 1979 the last known BFF 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 BFF on the porch of his Meeteetse, Wyoming home.
That population of Meeteetse, Wyoming BFFs was seemingly stable, numbering over 100. But, as a precautionary measure, a captive breeding program was launched to establish a back-up population to safeguard the species’ survival. Shortly thereafter, the species was put to the test. A Sylvatic Plague epidemic swept through the local prairie dog population in 1985, so too infecting the BFF population. With disease threatening the survival of the last few BFFs, 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 BFF, a living document designed to outline and assess recovery strategies and goals.
From 1985 to 1987, the last wild BFFs 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 BFFs were captured, with 18 breeding successfully, which represented the genomes of just seven founders. The first captive born BFFs were released to the wild in 1991 in Shirley Basin, Wyoming. The following year, a litter of kits was born in the wild at Shirley Basin. The Shirley Basin population is now a stable recovery population.
When the captive breeding program first began, the Recovery Team had the foresight to biobank 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 BFF 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 were as genetically diverse as the wild BFFs 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.