TOP: Nadine Pershyn carries a gray fox after trapping and collaring it. Pershyn and Max Larreur, both doctoral students at SIU, are working on the Illinois Gray Fox Project trying to learn more about the local animal. BELOW: Larreur sets up a camera trap to photograph gray foxes. BOTTOM: Pershyn (left) and research technician Nicole Mittman work on a gray fox before releasing it. (Photos provided)
December 10, 2024
SIU doctoral students research rare gray foxes in hopes of maintaining species
CARBONDALE, Ill. – Two doctoral students at Southern Illinois University Carbondale are trying to learn more about the gray fox, a local cousin of the more prevalent red variety whose ghostly presence still haunts the area.
Max Larreur and Nadine Pershyn are working with SIU researchers to unlock the gray fox’s secrets in Southern Illinois using a multiphase approach called the Illinois Gray Fox Project.
Larreur is working with long-term data from camera traps obtained almost 15 years ago to compare its current numbers as well as changes in its interactions among many species.
At the same time, Pershyn is busy trapping and fitting gray foxes with GPS collars to study their movements and survival rates.
Working separately but on the same species, the students hope their findings will help maintain the rare fox for generations to come.
“Gray foxes aren’t well studied, so the cause of the population decline is unknown,” Pershyn said. “While it’s likely not one singular cause, the decline cannot be addressed without understanding the species better.”
A common problem
A unique species with a special functional role in the environment, the elusive gray fox is set off from its red cousin by the flecks of gray blended within its red fur. They amaze researchers and even have the wild ability to climb trees; the only canid other than the East Asia raccoon dog that can do so.
During the past few decades, gray fox numbers have declined across the Midwest with no direct identifiable cause, said Clay Nielsen, professor of wildlife ecology and conservation with SIU’s Cooperative Wildlife Research Laboratory and the students’ co-adviser along with Guillaume Bastille-Rousseau, assistant professor.
Back in the mid-1970s, trappers were harvesting anywhere from 9,000 to 10,000 gray foxes annually in Illinois. Fast forward a decade later, and those numbers fell by 50% for gray fox while red fox harvest numbers remained relatively constant. More recently, during the 2015-2019 trapping seasons, fewer than 40 gray foxes were harvested by trappers.
Previous SIU research completed between 2008 and 2010 used camera traps to count gray fox numbers throughout the 16 southernmost counties in Illinois. Researchers measured habitat variables at camera sites to learn what the animal preferred and mapped similar habitat within those counties.
In the end, the research also indicated declining numbers of gray foxes, which supports what biologists have observed.
Nielsen said Illinois trappers, being aware of the decline, often have released gray fox in an effort to help maintain the species.
“Our research, funded by the Illinois Department of Natural Resources, will help wildlife biologists understand the ecology and status of gray fox in the Midwest,” Nielsen said. “Hopefully, it will also answer some questions regarding their population declines in the region.”
Picking up the ball
That’s where Larreur’s research starts. Starting in 2022 and going through 2024, Larreur began placing 1,267 camera traps throughout the same 16 counties surveyed from 2008-2010. Both surveys collected data from January through April during those years, although Larreur was able to set up about 80 more camera traps than the previous survey.
Larreur mounted the camera traps on trees about hip-height from the ground. Each camera uses a passive infrared sensor that requires both heat and motion to trigger, capturing a photo of whatever walks in front of it. At each site, he placed three camera traps about 250 meters (820 feet) apart from each other, forming a camera cluster, to provide a reliable representation of wildlife using the area.
Larreur then monitored each camera trap once a week, checking batteries and overall condition, and placing fresh sardines as bait. The result was 212,000 photographs, only 194 of which showing the gray fox.
Another intriguing finding: The numbers of gray foxes detected dropped off rapidly over the three-year study, from 104 in 2022 to none in 2024. And although the trend might partially be explained by a redeployment of camera traps to areas less proven by the previous survey to contain gray foxes, Larreur thinks the data backs the idea of declining population in the area.
“It seems like it’s just another point to support the hypothesis that their population levels are low and declining,” he said. “I was surprised how few we are able to find throughout Southern Illinois, despite having all those cameras out.”
Taking another approach
As Larreur is wrapping up his work with an anticipated graduation this coming spring, Pershyn is capturing gray foxes, placing GPS tracking collars on them, and studying their movements, home ranges and survival. She began her work in fall 2022 and anticipates completing it next year.
Pershyn first places trail cameras mainly throughout the Shawnee National Forest to identify areas where gray foxes are present. She then uses padded foothold traps to capture the foxes.
Once they are caught, she sedates them in order to safely collect morphological data and fit them with a GPS collar designed to fall off after a year before releasing the foxes near the capture location.
So far, Pershyn has managed to collar 11 gray foxes.
“I use the GPS location data to analyze where they are spending their time and how they move across the landscape,” she said. “The collars are equipped with a mortality sensor that allows me to study their survival. Blood and tissue samples taken during processing are sent off to inform a regional genetic and disease study about gray foxes.”
In particular, Pershyn hopes to learn how long gray foxes survive, common causes of death, their preferred habitats and movements. The answers in light of population decline have implications not just in Illinois but across the Midwest.
Understanding how the animal interacts with various vegetation covers and human presence could give wildlife managers insight into the types of habitats that are best for them, she said.
“Moving forward from there, if the population increases in the future, it will need to expand into suitable habitat that is not currently occupied, so how they travel across the landscape is critical,” she said.
SIU opening doors
Both Pershyn and Larreur are planning careers as wildlife scientists at universities. They credited working on the project through SIU’s Cooperative Wildlife Research Laboratory and its guiding faculty with putting them on the path to success in that field.
“It’s giving me experience leading a field project and overseeing technicians,” Pershyn said. “In my program in particular, it requires two semesters of teaching experience, which is invaluable for my future goals.”
Larreur said working with amazing advisers, graduate committee members, professors and other graduate students at SIU has undoubtedly contributed to his growth as a professional wildlife biologist.
“SIU has provided an amazing workplace and great experience over the course of my time here,” he said.