Deep in the Norwegian mountains, amidst a vast expanse of clear snow and howling winds, Toralf Mjøen throws a piece of meat into a fenced enclosure and waits for a pair of dark eyes to emerge from the snow pit.
These curious and playful arctic foxes know Mjøen well. He has been the caretaker at this breeding facility for 17 years and goes up the mountain daily to feed them at their camps near the small town of Oppdal, about 250 miles north of Oslo.
But Mjøen’s familiarity with the species goes back much further, from his years working at his father’s fox farm, where they bred the animals for their fur.
Now, years after the fur farms were closed, the arctic fox has become a symbol of conservation Norway. However, his long-term fate here is still in doubt.
“Sometimes,” says Mjøen, “there’s nothing we can do but try.”
Saving an animal from extinction is often seen as a series of dramatic steps, such as banning hunting to bring a species back from the brink of oblivion. But for arctic foxes and many other recovering but still fragile animal populations around the world, Mjøen says, “It’s all about baby steps.”
Every year since 2005, the Norwegian breeding program has released foxes born in captivity into the wild. Strictly measured by the numbers, it works: the population of arctic foxes has increased more than tenfold and they have spread to Finland and Sweden.
But the research team running the restoration project still feel they are far from the finish line. Especially in the last five years, killings by golden eagles at the breeding station and increased inbreeding in the wild have complicated the rescue operation.
“The problems we face today are actually due to the success of the program,” says the project’s leader, Craig Jacksonfrom the Norwegian Institute for Nature Research (NINA).
In the first decade, scientists were so focused on bringing the numbers up that they started with a population of about 50 foxes and bred them to more than 550 spread across Scandinavia, with about 300 in Norway.
But now he says, “It’s not just about producing foxes.” Instead, the goal is to increase genetic diversity in the population to make the animals more resistant to food shortages and the changing climate.
The project now meets all but one of the most important measures of success in a resettlement program, according to a study Jackson’s team published in 2022. The reintroduced foxes reproduce faster than they die, which is a good sign.
But there is still one major problem: they are still unable to sustain themselves without human intervention, depending on supplemental nutrition and lack of genetic resilience.
The only way to create more resilience is to rebuild the genetic diversity that was lost when the Norwegian population crashed decades ago, says Jackson.
He explains that arctic foxes prey on lemmings, a small rodent with a fluctuating population. Lemmings have been particularly difficult for foxes in recent years because the warm climate has created more opportunities for an invading competitor: red foxes.
Although red foxes were culled in Norway as an early measure to help arctic foxes recover, they still compete. A scarcity of rodents made it more difficult for arctic foxes to become a self-sustaining population.
If there are years with low numbers of lemmings, Jackson says, a more genetically diverse group of adult arctic foxes is more likely to survive because they are healthier and can compete for resources.
Jackson’s team tries to build diversity by introducing genetically different foxes into specific areas. But the fox’s deeply fragmented habitat makes it more challenging: they need to know exactly which groups of wild foxes lack diversity, so they know where to release the captive-bred foxes.
Øystein Flag Citythe geneticist of the captive breeding project, says it requires monitoring all the wild and released foxes to determine not only their numbers, but also their genomes.
Predation by golden eagles highlights another complication in captive breeding programs: as the animals must be concentrated in enclosures, they become more vulnerable to predators and disease.
Jackson’s team was forced to get creative to try to deter the golden eagles, according to a study published last year. Now the enclosures were strewn with bamboo sticks and ropes, but that was not enough.
Since 2019, the captive breeding facility, which usually has about 16 foxes, has had 11 deaths, nine of which were confirmed to be caused by golden eagles. Jackson, who relies on dozens of live camera feeds, tries to monitor the foxes from his office in Trøndheim, north of the breeding station.
Jackson logged in to check the live cameras in January when he saw an eagle waiting for a male fox. He hurriedly called Mjøen, the caretaker, but it was too late. In the video clip, an arctic fox looks small and defenseless against the powerful talons of a golden eagle.
Losing just one fox to an eagle means losing an investment of hundreds of thousands of Norwegian kroner, says Tomas Holmern, of the Norwegian Environment Agencywhich the station since 2006 at a annual cost of about 3.1 million crowns (£230,000). The program aims to improve the status of the fox population in Norway from threatened to just vulnerable by 2034, and its funding is guaranteed until 2026.
Holmern, a conservation biologist, cited other captive breeding programs such as the black-footed ferret in the American west and the California condoras examples of successful conservation efforts in improving the genetic diversity of a species.
In these cases and many others, the biggest obstacle is what conservation biologists call a “genetic bottleneck,” which happens when a population is reduced to a few individuals and loses its genetic diversity.
Building genetic variation back to a healthy level in a species can take thousands of years, say Klaus Kopfli, a geneticist at George Mason University’s Smithsonian Conservation School in Virginia, who has worked with black-footed ferrets. “That doesn’t stop us from trying,” he adds.
The black-footed ferret, he says, is still considered a conservation-dependent species because – like arctic foxes in Norway – they need people to keep their numbers up. If scientists step back and let nature take its course, the ferrets probably won’t survive.
A relatively new tool that can speed up the repair process is gene editing, which allows scientists to make changes to DNA that would otherwise take hundreds of generations, and is now being considered for some species to restore genetic diversity and correct harmful mutations set.
“Whether you’re talking about fish or birds or mammals or lizards, we can use the same tools for all those species,” says Koepfli.
Even in the midst of all the worries about the threats of the arctic foxes, there are signs of hope. And some of those signs are printed in the snow: fresh tracks of a wild fox, discovered in April. It’s a male, and he’s been circling the breeding station. Inside the camp is a female who lost her mate to an eagle in January.
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