Released black-footed ferrets are producing wild kits in southeastern Colorado
Finding them again, after you've released them into deep holes in the ground on southeastern Colorado's windswept prairies, is quite another.
Colorado wildlife officials are ecstatic to report at least two litters of wild-born kits at May Ranch, with an early September survey showing that recent attempts at reintroducing ferrets to North America are paying off.
More than 50 black-footed ferrets, bred in captivity near Fort Collins, have been tipped into prairie dog holes at May Ranch since 2021. The slinky, snarly ferrets are so elusive that horseback-riding May family members rarely see them again. But systematic state surveys of ferret release sites, employing everything from night spotlights to pet-chip readers, have this year produced both proof of surviving released ferrets and new offspring.
"We haven't seen it for several years, and so to see it this year was really exciting and encouraging. When you go several years and you haven't confirmed it, you're kind of just wondering what's going on at the site, if all the animals have been predated," said Dan Neubaum, species conservation program manager for Colorado Parks and Wildlife. "So that was really good news."
A release site at the old Pueblo Chemical Depot, also good prairie dog habitat, is also reporting new kit sightings this year, Neubaum added.
After decades of releases and more than 10,000 black-footed ferrets bred in captivity, wildlife officials still estimate only a few hundred survive at release sites around North America. The plague that hits both ferrets and their prairie dog hosts can wipe out a revived colony in one season.
The ferrets were considered extinct for years before a Wyoming dog dropped a dead ferret on a ranch doorstep in 1981. Scientists swept up all the ferrets from a nearby, unknown colony, and put them in a federal breeding center. Only seven survived for reproduction. Thousands have been born since then, but researchers believe one reason release survival rates are so low is the extremely narrow genetic stock, with every ferret descending from those original seven. They have now cloned a ferret from frozen genetic stock, and hope to expand the breeding pool.
Colorado and U.S. Fish and Wildlife specialists cooperate to release ferrets raised north of Fort Collins at May Ranch and other sites, including the former Pueblo Chemical Depot. Every released ferret is pet-chipped under their fur.
They are also vaccinated for the plague. Once on site, wildlife officers add on more elaborate inoculations for the dreaded plague, including dusting with an insecticide to kill plague fleas and dropping vaccine-laced food pellets for both the prairie dogs and the ferrets who invade their burrows. (About 90% of the ferret's diet is prairie dog meat.)
Wildlife experts call black-footed ferrets a key species in the West, interacting with 130 other species up and down the food chain. Healthy ferret populations promote a circle of animals ranging from golden eagles to burrowing owls to rattlesnakes and badgers.
The released ferrets immediately disappear, though, and any kits they have of course are not chipped for tracking. CPW's annual proof-of-life survey includes a few methods:
"Based on that and some other bits of information where they made their sightings," Neubaum said, CPW officers working near Lamar "thought that they had at least two different groups of adult ferrets that were released last year that have resulted in kits this year. So at least two litters, basically. And that's pretty exciting, because over the past several years, we've released a fair number of ferrets and haven't seen reproduction, and so we've been a little concerned that some of the released ferrets aren't surviving very long."
Another release of captive-bred ferrets is planned for later this fall at May Ranch and other locations. Southeastern Colorado officers have a plan to give the new residents a boost, Neubaum said. They will put an electric fence around the prairie dog colony where ferrets are tipped into the existing burrows, hoping to keep coyotes and badgers away from the newcomers until they get established.
The baby ferrets are a "testament," May Ranch co-owner Dallas May said, to the work that state and federal agencies have done to "bring back all species to try to keep the chain of biodiversity intact."
May is also chair of the Colorado Parks and Wildlife Commission and supports co-survival of native species on ranchland.
Every ferret reintroduced to the ranch faces a variety of threats, May said.
"There are so many factors today trying to strip all of this away," he said. "It is great to see some success. The challenge is to keep it going."
