Over the past 20 years, one of the most endangered mammals in North America has been making a comeback with a vengeance, thanks in a large part to the innovative work of the National Zoo’s Conservation Biology Institute. This year the National Zoo, in conjunction with the U.S. Fish & Wildlife Service and other stakeholders, celebrates the 30th anniversary of the discovery of the last remaining wild black-footed ferrets—thought to be extinct—and the 20th anniversary of the species’ re-introduction to their native habitat.
A half-million or more black-footed ferrets (the only ferret indigenous to North America), once lived in the short- and middle-grass prairies of the western Great Plains stretching from southern Canada to northern Mexico. Tragically, the population was devastated when the species’ primary food source, the prairie dog, died off from disease and overzealous population management. Between 1985 and 1987, researchers collected the surviving 24 wild black-footed ferrets and brought them into captivity. Only 18 survived. Since settlers arrived on the plains, these charismatic animals have faced serious threats. Ranchers saw the prairie dogs as a competitor to their cattle and killed them by the millions, in turn starving the ferret. A disease called sylvatic plague wiped out both prairie dogs and black-footed ferrets, ultimately resulting in a 98 percent loss of prairie dog habitat.
When researchers realized the surviving population had dwindled to only 24 wild black-footed ferrets near Meeteetse, Wyoming, they were left with only one option: to take the animals into protective captivity and breed them with very little information about or experience on how to do so. The National Zoo became the first to receive the offspring (called kits) of the original surviving population of wild ferrets. Since then, the Smithsonian Conservation Biology Institute has made significant breakthroughs in understanding the biology of this species and breeding it both naturally and through artificial insemination; in managing a population with severely depleted genetic diversity and in freezing sperm and using it to inseminate female black-footed ferrets even 20 years after researchers collected and froze the sperm. In total, SCBI has produced 670 black-footed ferrets at the National Zoo’s Front Royal facility, and 300 of those have been reintroduced to their natural habitat in one of the Zoo’s most successful conservation endeavors to date. The remaining ferrets were held back for captive breeding in subsequent years to ensure that the most genetically valuable ferrets were represented in the population. About 1,000 black-footed ferrets live in the wild today.
In addition to the Zoo’s Front Royal facility, black-footed ferrets are also managed and bred at the Louisville Zoological Garden, Toronto Zoo, the Phoenix Zoo, Cheyenne Mountain Zoo and the USFWS National Black-Footed Ferret Conservation Center. Each year, between 150 and 220 black-footed ferrets are preconditioned and reintroduced into the wild. Since 1986, more than 7,100 black-footed ferrets from these breeding institutions have been released into prairie dog colonies across North America.
Posted September 2011