In the centuries of explosive American expansion that followed, the foxes, like so much other wildlife, found their habitat decimated. Settlers, seeking their own piece of the West, converted vast stretches of prairie into farmland. Waves of colonization followed, bringing with it the encroachment of railroad tracks, roads, towns, and eventually cities.

Since Lewis, every naturalist and scientist who wrote accounts of swift foxes or studied their movements agreed that they were creatures of the shortgrass prairies within the Great Plains. The ecosystem stretched from Canada to Texas, and the foxes were believed to live nowhere else.

More than two centuries after Lewis and Clark, swift foxes are surprising researchers with how adaptable they can be. They’re showing up in a completely different habitats, more than 60 miles west of the prairie land that experts agreed was their only home. A few of these early observations came from a student and wildlife enthusiast named Dana Nelson. Nelson first saw a swift fox in western Wyoming in 2017 and has spotted several more in the years since.

“It just doesn’t compute with what you’re used to seeing and reading,” said Nelson, whose doctoral research at Clemson University focused on the foxes. “Every single paper talks about swift foxes needing short stature grassland and large tracts of prairie.” But there they were, in habitats dominated by knee- or even waist-high sagebrush.

As sightings continued to stream in from the scrublands, they got the attention of wildlife managers at the Wyoming Game and Fish Department. In 2022, they joined scientists from the University of Wyoming and the Bureau of Land Management to track swift foxes in the BLM’s Lander Field Office in western Wyoming. They published their results this June in the journal Wildlife Biology.

Austin Smith, a research scientist at the University of Wyoming and lead author of the study, was excited to learn more about how a vulnerable species thought to be limited to one habitat could potentially spread to another. It seemed like good news, a rare and precious commodity in 21st-century wildlife biology.

“We’re in a world where species decline is evident globally. We’re constantly dealing with habitat loss, habitat destruction, disturbances, you name it,” said Smith. “Hearing of sensitive species getting any sort of gain, especially in what would be considered an unconventional habitat, would definitely come off as a win. And it could be.”

But as Smith and his colleagues’ work showed, that win could come with some caveats and complications.

Swift foxes are not federally listed as threatened or endangered, but they are listed as a tier-2 “species of greatest conservation need” at the state level in Wyoming. That means that the state considers their population relatively stable, but ranks various threats like habitat loss, predators, and human impacts as “severe.” This, like all management decisions for the foxes made in the last century, was based on an assumption that they were a grassland obligate.

It had long been scientific and management dogma that, because of their size and vulnerability to larger predators, like coyotes, swift foxes needed the long sight lines that shortgrass prairie provides. If there were too many trees or shrubs to block that sight, the thinking went, they could be picked off and might not survive and reproduce nearly as well.

Along with their own survival, one of the big questions surrounding the scrubland foxes is what effect they could have on species native to that habitat. Research on the westernmost foxes’ diet is still ongoing, but one new prey item on the menu, said Smith, may be the kangaroo rat, a common and widespread small mammal of Great Plains scrublands. Kangaroo rats are already an important prey species for many other predators, including coyotes, owls, hawks, and snakes. It will take more time and study to know whether a new carnivore on the scene will impact prey species or outcompete existing predators.

Meanwhile, Nelson’s doctoral work was part of a reintroduction project in Montana that could bring the foxes back to an important corner of their former range. Her team hopes the reintroduction will help researchers understand the long-term effects and potential success of the Wyoming foxes.

The Fort Belknap Indian Community is made up of the Assiniboine (Nakoda) and Gros Ventre (Aaniiih) nations. The community includes over 7,000 enrolled tribal members. Their 675,000-acre reservation in northern Montana is a small remnant of their ancestral home, which they shared for millennia with species they recognize as relatives.

Fort Belknap is one of the rare places where three prairie species, once all but extinct, now roam free: the bison, the black-footed ferret, and as of 2020, the swift fox. That year, a five-year reintroduction program began with the release of 27 foxes on the reservation.

“It could not have happened without Fort Belknap Indian community’s willingness to partner with conservation organizations,” said Nelson. The tribal council passed a resolution to start the process, and elders and community members guided the logistical and scientific work, such as deciding on the best sites to release the foxes, as well as the spiritual ceremonies welcoming their relatives back to the land.

Species reintroductions are long-term efforts, and the Fort Belknap project is still in its early years. But the early signs are promising, including many dens and newborn kits on the reservation. It also led to several findings that could inform the study of the new population of foxes in western Wyoming scrubland.

The foxes being reintroduced to Fort Belknap were taken from four sites, including one in Wyoming’s Shirley Basin, which featured more scrub habitat than the others. Nelson and others guessed that the foxes caught there might settle into some of the more scrub-dominated parts of the reservation. But that didn’t happen. No matter where the foxes came from, they consistently chose the most grass-dominated habitat.

Due to their small size, swift foxes are less associated with livestock conflicts than larger canids, like wolves and coyotes, but they can still be threatened by proximity to humans. One of the leading causes of death for swift foxes is being hit by cars. Secondhand poisoning by rodenticides can also kill foxes. Without support from the tribal nations, the reintroduction could not have happened, and likewise, without buy-in from local communities in western Wyoming, the fox population there will have much less chance to thrive.

Smith sees this as an especially exciting time to study swift foxes, and not just because of the shift into new habitat. New technologies are allowing researchers to gather new insights into the foxes’ daily lives. Until recently, the collars and battery packs that Smith’s team used to track the foxes were just too big and heavy to load onto such a small animal.

“It’s only been in the last handful of years that we have the technology that we can put a collar on them,” said Smith. “Swift foxes are the size of a house cat, so you can’t put a lot of weight on them, but the technology is finally there.”

In addition to lighter tracking equipment, environmental DNA and metabarcoding advances give researchers a new, less invasive way to track fox diet. With these tools, every piece of fox scat is a potential gold mine of prey DNA.

There may be more good news for the future of swift fox conservation. Nelson coauthored a paper published last year in the journal Landscape Ecology, which concluded that swift fox suitable habitat is set to grow significantly under the most likely climate change scenarios. The study suggests the northern edge of their range could be limited by extreme cold or snow so deep that it makes hunting difficult. Future warming is likely to expand their range significantly to the north and northeast. But unlike other grassland animals like black-tailed prairie dogs, expected to be pushed north by climate change, the models in Nelson’s study did not show much loss of the more southern habitat. Rather than a shift in habitat, it looks like mostly a gain for the foxes.

Between the new population in western Wyoming, so-far successful reintroductions in Montana and elsewhere, and potential increases in habitat in the coming decades, the swift fox has the potential to be a conservation success story. But as both Smith and Nelson pointed out, there are still many questions to be answered, and a long way to go before this small, shy fox of the American prairie is out of the proverbial woods.