A new study from UW and Grand Teton shows complex relationship between foxes and people
September 28, 2023
A red fox jumped into someone's golf cart in Grand Teton National Park a few summers ago, presumably looking for a snack. It wasn't the fox's first foray into begging humans for food, and it wouldn't be his last. After hopping on occupied picnic tables and stealing fish from ice fishermen, park rangers ultimately trapped and killed the creature.
It's one thing for foxes to linger near campsites and pose for the occasional photo, it's another for a fox to hop up next to a person. Red foxes aren't as dangerous as other park wildlife like bears, but they can still spread rabies or even bite, park officials said.
Red foxes weren't always a noticeable presence in Grand Teton campgrounds. The first fox killed by a car was 2005. By 2015, seven to 10 foxes were being hit each year, said John Stephenson, a wildlife biologist at Grand Teton National Park. And while no one knows exactly how many foxes now live in the park, Stephenson wanted to understand how big a role humans and their delicious food had to play in an increase in fox activity.
What he and other scientists learned shows that red foxes, like so many species, are rarely as simple as we like to think.
Human versus natural foods
A handful of years before the golf-cart incident, Stephenson decided the park needed to start studying foxes. Foxes were increasingly begging from people - some would even sit in campgrounds with their ears softened begging like a Labrador. They were also hit by cars more often.
Stephenson wanted to know if red foxes were being actively fed by humans, if they were finding food in places like garbage cans, if they were simply denning in the area or if they were taking advantage of the apparent safety from other predators humans can potentially provide. Individual tags would let him and other biologists know if all red foxes in the park begged for food or if it was only a few and the entire species was getting the blame. Lastly, he wanted to gain a basic idea of red fox ecology in the park including how far they roam in their home ranges, what else they eat and where they tend to spend time.
Over the course of four years, he and other biologists captured dozens of foxes, placed tags in their ears, collected hair and whisker samples for diet analysis and drew blood for genetic and disease testing. In 2020, they partnered with UW assistant professor Joe Holbrook, brought UW graduate student Emily Burkholder onto the project and captured more foxes.
Burkholder helped the researchers finish collecting data and begin synthesizing years of location data points and the stable isotopes of the foxes' hair and whiskers, which could tell her if the creatures were eating human or wild foods.
What she found began to answer at least a few of those basic questions.
First, she realized some foxes in Grand Teton are habituated to humans - which means they tolerate their presence - and others are food conditioned - which means they actively seek out human food.
"I have a picture of one with a whole loaf of bread in his mouth. He is food conditioned," Burkholder said. "Another fox I would see often, but based on her diet results, she did not consume human food. She wasn't afraid of me, but she wasn't seeking out food sources."
She also found adult foxes were more reliant on human food than juveniles, potentially because they either had to learn to find food from humans or because adults were monopolizing the resource.
It's easy to assume foxes seek human food because it's readily available, or they're hungry, but summers in Grand Teton are full of wild fox foods like mice, voles and ground squirrels, Holbrook said. Why there seems to be an increase in fox activity near campgrounds and in the park in general is a mystery he and Stephenson hope to solve.
Possible human shield
Stephenson, Holbrook and Burkholder are careful never to say Rocky Mountain red foxes are more abundant in the park than they were decades ago. No one kept records of the creatures. Anecdotally, however, Stephenson can say they seem to be more abundant.
In the 1980s, biologists noted red foxes in the park's rare species database about once a year. In the 1990s and early 2000s, sightings bumped to about three a year.
"The first interesting thing about that was biologists considered them rare," Stephenson said. By the mid-2000s, rare species records for red foxes stopped altogether, presumably because they became so common.
Stephenson also cites the roadkill database. And while he stresses neither of those measurements are scientific, they do paint a picture of a species that is native to the area but now appears more plentiful.
He and Holbrook have a theory for why, and it coincides with the reintroduction of wolves.
"Wolves came to Grand Teton in 1998, and the first pack formed in 1999, and so the idea is that wolves would displace coyotes and that foxes could fill those voids," Stephenson said. "Wolves are competing directly with coyotes. They are not directly competing with foxes."
In other words, red foxes may be capitalizing on human presence, but not as a way to hide from wolves. Instead, they may be merely filling a space left behind by coyotes as wolves have either killed or displaced the lesser canids, Holbrook said.
It's still a theory, he added. Foxes may also be spending more time around humans because human structures and activity tend to attract mice, voles or ground squirrels. Or they could be using buildings as denning areas.
Holbrook hopes he'll have an answer to the increase in the next handful of years as another graduate student begins work on the project.
As for foxes wandering in and out of campgrounds, Stephenson said park rangers can continue hazing foxes that spend too much time around humans. They could also potentially haze juveniles as a way to delay or prevent them from becoming adults that seek human food, Holbrook said.
Park officials may also step up educational efforts for humans, because bears aren't the only creatures people need to keep away from snacks.
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