Unusual airlift propels extinction prevention
Local blackfooted ferrets transported to Arizona
As the moon rose over the Rocky Mountain Arsenal National Wildlife Refuge one night last week, two small planes waited on a runway across town, ready to receive highly finicky travelers that traditionally haven’t been part of the jet set: endangered baby blackfooted ferrets.
They’re dying elsewhere, but proliferating here at this refuge established on militaryindustrial wasteland northeast of Denver. Suddenly, wildlife managers outside Colorado are eager to import the animals.
It fell to a team of U.S. Fish and Wildlife Service biologists and technicians, gathering at the refuge ear four large trucks mounted with brightlight scopes, to round up 14 wildborn ferrets from the underground burrows of prairie dogs — their prey.
That’s easier said than done. The wildlife refuge spans 23 square miles and is riddled with interconnected prairiedog tunnels. And efforts to entice ferrets with bait, even coated with peanut butter, have failed.
“You have to be in the right place at the right time. It is a needleinthehay stack game,” refuge manager Dave Lucas said as he rolled out in one truck. “We should see a couple dozen ferrets tonight. Hopefully.”
“I’m not sure how many we will catch,” he added. “The trick is figuring out which hole they go down.”
Their ordeal over the next 12 hours to coax wildborn ferrets out of prairiedog tunnels and into cat carriers for an unusual airlift to Arizona gives a glimpse of the hidden hard work devoted to preventing the extinction of
species around a perilous planet.
Back from the brink — twice
Blackfooted ferrets rank among the most endangered among the 2,345 animals and plants listed by the U.S. government as facing imminent extinction, a number increasing by 3 percent a year. (Those include 1,661 species inside the United States, up from 1,436 in 2013.)
Scientists generally agree that extinction rates for the 1.9 million animals and 450,000 plants they have identified are accelerating, estimating 100 to 1,000 species per million vanish each year. Habitat loss and climate change increasingly are to blame, hammering animals that play crucial ecological roles on land not yet developed for housing and commercial expansion.
Ferrets twice last century were deemed extinct. But, since 1967, they have survived on the U.S. endangered species list — longer than most other species. They are furry native predators with coneshaped noses and eyesight, hearing and smell so acute they can hunt underground in the dark.
But their future is still considered shaky despite a 40year, $55 million national project — revolving around a National BlackFooted Ferret Conservation Center northeast of Fort Collins, the federal government’s ferret breeding complex — to restore them across Great Plains grasslands from Canada to Mexico.
Until recently, it looked as if reintroduced ferrets might be reaching the point of sustaining themselves on a 100,000acre ranch in the Aubrey Valley of Arizona, one of four primary recovery sites. A sudden dieoff this year compelled this emergency interstate airlift, one of the first in the push to save blackfooted ferrets.
The airlift reflects the emergence of the Rocky Mountain Arsenal National Wildlife Refuge as a venue for species recovery following a $2.1 billion environmental cleanup. Previously, the U.S. military made chemical weapons and Shell produced pesticides, including DDT, at the arsenal before it was declared an environmental disaster.
Federal wildlife managers over the past month counted 56 new ferrets that they’ve never seen before on their surveys, including a record 50 wildborn kits. They have been vaccinating ferrets and prairie dogs for years to combat sylvatic plague, which spreads from infected fleas to prairie dogs and then ferrets. They estimate an overall refuge population of more than 100 blackfooted ferrets, after a reintroduction of 30 captivebred ferrets in 2015.
The success here stands out among 29 public and private sites where federal biologists in recent years released captivebred ferrets. However, the refuge, sandwiched between Denver International Airport and an expanding metropolis, may have exceeded its carrying capacity for ferrets, mortality data suggest. At least six wandered away from prairiedog colonies and were killed by vehicle traffic on Peña Boulevard, which leads to DIA, and other surrounding roadways.
For recovery, the latest research has found wildborn ferrets are far more resilient compared to ferrets raised and conditioned at the federal captivebreeding complex, where newborns are fed prairiedog meat and obstacle courses made with black tubes simulate hunting conditions.
“Dude, please stick your head up again”
The refuge on this recent night sat silent, 8 miles from downtown Denver, an oasis resembling shortgrass prairie, dark enough that stars shine. The crew members looking for ferrets had to watch for deer or bison. (The bison herd this year grew to a recordhigh 180.) Prairiedog colonies are located away from a 1,084acre core that a U.S. Army team patrols, an offlimits area where toxic waste was buried and capped.
The crew members — some already had worked day shifts — bundled up for extended work out in temperatures dipping to 40 degrees. They ate Cracker Jacks and gummy bears for energy. Atop each truck, the scopes, imported from Australia, beamed pale white pillars of light as far as four soccer fields through the darkness toward prairiedog mounds.
Ferrets can propel their slinking, elongated, pearshaped bodies faster than snakes. They’re sensitive to weather. Any mist, wind or rain drives them determinedly underground. But big moons bode well, crew members said.
And Lucas had the benefit of volunteer wildlife tracking ace Talon Vanderbloom, 19, riding shotgun. Determined to become a federal wildlife officer once he goes to college, Vanderbloom is able to spot ferrets at great distances.
He and Lucas aimed the lights, scanning the dark terrain. After a few minutes, Vanderbloom steadied one beam.
“Something behind that bush,” he said, nodding at vegetation about 300 yards from the truck. “That’s a ferret.” Lucas turned the wheel. “I’m going to boogie at him. Hang on.” He accelerated the truck, bouncing over ruts and mounds toward that lit bush — only to find, when they got there, that the ferret turned out to be badger.
“Our nemesis,” Lucas said. “They look just alike.”
The best strategy, crew members said, would be to exploit blackfooted ferrets’ natural curiosity. At safe distances, they peer up from holes like meerkats — sapphire green eyes staring back into the search beams.
The team consensus at midnight: “Slow so far.” Nobody had any ferrets. But then things picked up.
“Looks like a ferret, looking left. … Yep. … Definitely a ferret. … Dude, please stick your head up again. … There he is. He is definitely lowridin’. … Hey, buddy! … It’s a good start. … He seemed kind of curious. We might have a good shot with him. … He’s looking at us, isn’t he? … I think we visited this den before. … Let’s try it. … I saw him. He went back down that hole.”
The refuge crew members inserted 4foot metal cages into the tops of the prairiedog burrows where they’d seen ferrets descend. Then they put clear plastic 7Eleven softdrink cups, purchased in bulk from a wholesaler, over the tops of surrounding holes — capping escape routes.
Soon they had several fer rets chattering in cages.
Endangered Species Act of 1973
Arizona Game and Fish officials said their Aubrey Valley population of reintroduced blackfooted ferrets peaked in 2013 at 123, and this year decreased to nine. They wanted to get new wildborn ferrets — and others bred in captivity — into prairiedog colonies as smoothly as possible to reverse the decline and conduct an experiment to figure out whether plague, coyotes or other factors are to blame for the dieoff.
Arizona biologist Maeghan Miller worked alongside the federal crew at the Rocky Mountain Arsenal refuge.
“We’re trying to determine the cause of death, whether it is predators or disease,” she said. “We’ll be putting collars on them. We’ll track their movements. If they die, we want to be able to look at them.”
The Endangered Species Act of 1973 requires action to remove species listed as facing imminent extinction. So far, 54 listed species have been recovered while 11 went extinct, federal records show. The idea is to restore a balance of predators and prey and revive ecosystems by resurrecting natural processes for the future.
When the crews trapped the ferrets at the refuge, they brought them in cages to a mobile lab for verifying that each had been implanted with a data chip the size of a grain of rice, and vaccinated against plague. Inside the lab, federal veterinarian Della Garelle set up a surgical area and, using a special anesthetic for small mammals that had been imported from Switzerland, implanted chips where needed and gave booster shots of a vaccine against sylvatic plague, which spread to the United States around 1900 and continues to ravage prairiedog colonies and kill ferrets.
Garelle saw the difference between captivebred and wildborn ferrets.
“They are definitely more buff, muscly. The boys are fatter,” she said, guiding one back into a cage, careful to avoid bites.
“If you can support blackfooted ferrets, then you know you have a healthy prairie.”
While saving large animals facing extinction such as elephants and giraffes is considered increasingly difficult, federal experts say they see better potential for species that once thrived on the Great Plains.
“This recovery is so doable — compared with tigers, great apes and wolves,” Garelle said. “For those animals, there may be no habitat. But for the ferrets, the habitat exists.”
Shortly after sunrise, one of the two small planes from Arizona took off from the runway at the Rocky Mountain Metropolitan Airport in Broomfield, hauling 17 captivebred ferrets driven down from the federal breeding complex in Fort Collins. Then Miller and the refuge crew members loaded 14 wildborn ferrets in cat carriers into the other plane.
That aircraft took off at 10 a.m. Once it reached Arizona’s Aubrey Valley, the ferrets were moved swiftly to prairiedog colonies for feeding as bleary wildlife recovery crews in two states began to recover themselves.
Bruce Finley: 3039541700, bfinley@denverpost.com or @finleybruce
“This recovery is so doable — compared with tigers, great apes and wolves. For those animals, there may be no habitat. But for the ferrets, the habitat exists.” Federal veterinarian Della Garelle