Back From Extinction
A Tale Of Ferret Survival At The Rocky Mountain Arsenal
Story and photos by Reid Neureiter
For the GPHN
In 1979, the black-footed ferret, North America’s only native ferret species, was declared extinct. That was a mistake.
In a triumph for the conservation movement, the black-footed ferret, (“BFF” for short), while still endangered and not quite thriving, is at least surviving on the grounds of the Rocky Mountain Arsenal National Wildlife Refuge just six miles north of Park Hill.
The Refuge even has a public exhibit with two post-reproductive “ambassador” ferrets — a male named “Hops” and a female named “Yo.” The ambassadors help to educate the public about endangered species, biodiversity and importance of habitat protection. In July, the Greater Park Hill News was given exclusive access to view and photograph the feeding of Hops and Yo, as the exhibit remains closed to the public out of fear that the animals may be susceptible to the COVID-19 virus.
The black-footed ferret’s near-extinction is the story of Western expansion and habitat loss. The ferrets are prairie dog hunters, and in the wild their diet consists almost exclusively of the charismatic rabbit-sized rodents. The ferrets make their dens in empty prairie dog tunnels.
Prairie dogs were considered pests in much of the American West. Beginning in the early 1900s, large-scale poisoning campaigns decimated the prairie dog populations, and thus, the ferrets as well. In addition, agricultural development of the Great Plains meant that 98 percent of the shortgrass prairie habitat where prairie dogs and ferrets live has been plowed under. In a triple whammy, black-footed ferrets are singularly susceptible to canine distemper and the sylvatic plague. So, by the 1970s, the species was believed to have gone the way of the dodo bird — succumbing to habitat loss and disease.
A ranch dog named Shep
But in 1981, in Meeteetse, Wyo., a ranch dog named Shep brought a weasel-like carcass back to his owners. It was correctly identified as a black-footed ferret and conservationists discovered a remaining hold-out population of about 100 animals. That population too was then ravaged by the plague, leaving only 18 survivors.
At the time, the black-footed ferret was considered one of the rarest mammals on the planet. In 1986 the decision was made to try to save the species by capturing the surviving animals to start a U.S. Fish and Wildlife-managed captive breeding program.
The resulting Species Survival Plan involved establishing six captive breeding facilities across the country. One of those, in Larimer County in northern Colorado, now houses two-thirds of the world’s captive breeding population of black-footed ferrets.
Of the 18 captured ferrets, only eight reproduced in captivity. Thus, with one recent exception, the world’s entire existing population of black-footed ferrets is descended from those eight animals. That means the species also is at risk of genetic problems due to inbreeding.
However, technology is already in play to address the lack of genetic diversity. Last year, on Dec. 10, a black-footed ferret was successfully cloned. “Elizabeth Ann” was created from the frozen cells of “Willa,” who lived more than 30 years ago.
“Although this research is preliminary, it is the first cloning of a native endangered species in North America, and it provides a promising tool for continued efforts to conserve the black-footed ferret,” said Noreen Walsh, director of the U.S. Fish and Wildlife Service’s Mountain-Prairie region. “Successful genetic cloning does not diminish the importance of addressing habitat-based threats to the species or the Service’s focus on addressing habitat conservation and management to recover black-footed ferrets.”
Curiosity traps the ferret
Though there have been challenges, the captive breeding program has been successful enough that the ferrets are being reintroduced into the wild in 30 locations across the country (and in Mexico and Canada).
According to the Fish and Wildlife Service, the Rocky Mountain Arsenal National Wildlife Refuge was chosen as a ferret reintroduction site because of its healthy expanse of shortgrass prairie and abundance of black-tailed prairie dog colonies. In October of 2015 and again in September 2016, ferrets from the Larimer Conservation Center were introduced onto more than 1,300 acres of the Refuge’s prairie.
Biological Science Technician Erin Mihlbachler, described the Refuge’s annual ferret population survey. Because the ferrets are nocturnal, the survey happens at night, from 9 p.m. to 7 a.m., with rangers and technicians shining powerful lights across the grassland. The ferret’s eyes are reflective, allowing the surveyors to pinpoint the prairie dog mounds where the animals can be found.
Mihlbachler said that small mammal traps then are placed near the mound where the ferrets have been seen. As the ferrets are extraordinarily curious, they will investigate and usually will be trapped within minutes for an annual check-up.
All of the ferrets are pre-vaccinated for rabies, canine distemper, and plague, giving them the optimal chance of survival. The wild-born kits that are trapped during annual surveys are vaccinated and microchipped before being re-released.
Mihlbachler said that a 2019 survey showed a healthy Refuge population of 88 adult ferrets. An outbreak of sylvatic plague in the Refuge’s prairie-dogs subsequently spread to the ferrets, and the most recent survey, in September 2020, only 27 adult animals were found.
While the ferrets are predators, they are themselves preyed upon by hawks, owls, badgers and coyotes. Mihlbacher said one of the ferret surveys was interrupted when the surveyors saw a great-horned owl snatch one of the rare ferrets for its dinner.
Inquisitive, Intelligent, And Undeniably Cute
Ferret Ambassadors Hops And Yo Solve The Dinner Puzzle
Black-footed ferrets are members of the Mustelid family, which also includes weasels, badgers, otters, wolverines, mink and ermine. The ferrets are 19 to 24 inches in length and weigh between 1.5 to 2.5 pounds. With droopy mustache whiskers, bandit-like black masks, and characteristic black feet, they are inquisitive, frenetic, and undeniably cute.
The feeding process for the ambassador ferrets, Hops and Yo, is a fascinating process. During a recent visit Lissette Montano, an intern at the Refuge’s visitor’s center, stimulated the ambassadors by providing their food (previously frozen and re-heated mice) as puzzles to be solved.
The dead mice were placed in paper lunch bags, which were then rolled up. A rock was placed on top of the bags. The male ferret, Hops, was quicker at solving his dinner puzzler, quickly removing the rock, unwrapping the bag and taking the first of two mice to a hole to eat. Mihlbacher said new toys — such as cardboard boxes or plastic balls — are routinely incorporated to keep the intelligent and hyper-curious animals stimulated.
Adult ferrets are solitary animals, and so Hops and Yo are in separate enclosures. “Otherwise,” said technician Erin Mihlbacher, “there would be problems.”
While the black-footed ferret exhibit at the Refuge remains closed to the general public, people can see the prairie dog towns where the Refuge’s wild ferrets live near mile marker 5 on the Refuge’s Wildlife Drive. More information about black-footed ferrets and recovery efforts can be found at blackfootedferret.org.
— Reid Neureiter