Understanding Gray Fox Distribution Throughout Southern Illinois Forests

Over the past few decades gray fox (Urocyon cinereoargenteus) numbers have been declining across the Midwest with no direct identifiable cause. 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 percent for gray fox while red fox harvest numbers remained relatively constant. Now, during the 2015-2019 trapping seasons, less than 40 gray foxes were harvested by trappers, although trapper numbers have also declined since the 1970s (more than 21,000 trapping licenses sold in 1979 compared to 6,700 sold during the 2019-20 hunting year).

Potential causes of these declines could be anthropogenic influences, disease, increases in competitor populations, and habitat loss/fragmentation. Coyotes are known to especially hamper gray fox populations through direct predation and displacement. But with decreasing reported sightings of gray fox in trapper reports, and supporting evidence from Illinois Department of Natural Resources (IDNR) archery deer hunter surveys, gray fox numbers have clearly declined across Illinois and other Midwestern states. In Illinois specifically, IDNR has listed gray fox as a “watch list” species in their Illinois Wildlife Action Plan (IWAP). Species on this watch list are designated as wildlife that have “poorly known distributions, status, trends, or specific habitat needs in Illinois.”

Gray foxes are an opportunistic omnivorous mammal thriving in forested areas across their native range and are rarely seen as they are normally active during twilight and nighttime hours. Ranging from 6 to 15 pounds and about 3 feet in length from head to tail, their salt-and-peppered coloring along with hints of red, orange and white give them a distinctive look compared to their elegantly colored relatives, the red fox. Gray fox may also be referred to as “tree fox” or “cat fox” due to their elusiveness and ability to climb trees to escape predators such as coyotes, find food, or even den.

Gray fox play economically and ecologically important roles in forested ecosystems. Gray foxes are an economically beneficial furbearer species given that they serve as a source of conservation funding generated from licenses purchased by sportsmen and women who hunt or trap them. Economic benefits are also gained through the fur prices hunters and trappers garner from their efforts when successful. During the 2019-2020 trapping season, 6,700 trapping licenses were sold. Gray fox pelts were worth about $10-15 individually. Ecologically, gray fox prey on rodents and smaller mammals acting as a source of population control. This predator-prey relationship plays a significant role in small mammal populations across gray fox range.

With funding from the IDNR and the Federal Aid in Wildlife Restoration Act (Pittman-Robertson Act), we at the Cooperative Wildlife Research Laboratory (CWRL) at Southern Illinois University are conducting a multi-year study on gray fox ecology in Illinois. Phase I of this research includes setting up camera traps throughout southern Illinois to assess gray fox distribution and habitat associations. A similar, previous study completed in 2010 placed camera traps and measured habitat variables at camera sites to assess habitat attributes associated with gray foxes and mapped their habitat throughout the 16 southernmost counties. This research indicated declining numbers of gray foxes, which supports what biologists have observed in the other data listed above. Gray foxes used habitats associated with anthropogenic features as well as forested areas. Attraction to human development could be caused by the associated presence of easy food sources (such as rabbits, squirrels and other rodents) and habitat beneficial to raising young, or a decrease in interactions with competitors such as coyotes.

The results of our prior research provided a map of gray fox distribution throughout southern Illinois. Our current study will test the validity of these maps 10 years later. We are especially interested in rates at which gray fox are colonizing new areas and abandoning others, while keeping an eye on interactions with potential competitors such as coyotes. Understanding the changing distribution of gray fox throughout Illinois will help in the development of accurate and effective management plans aimed at protecting this species.

This work will help focus Phase II of our project which involves capturing gray foxes, placing GPS tracking collars on them, and studying their movements, home ranges, and survival. Having updated maps of gray fox presence will certainly help us determine places to capture gray foxes by focusing on potential study areas within Illinois having the most likely gray fox habitat. This project will begin in the fall of 2022 and we are seeking information from the public to help in our efforts for both Phase I and Phase II.

We are seeking information from throughout Illinois on the gray fox. We have established a website where you can find out more about our project and access a form for visitors to send in information on sightings of gray foxes, either alive or dead. Live gray foxes may be directly observed in your yard, crossing a road, from a deer stand or game camera, or from animals captured during the legal fur harvest season. Dead gray foxes are likely to be observed as roadkill. Having GPS locations of these events is important to both phases of the research, and we thank you in advance for your efforts in helping us understand gray fox status in Illinois!

Max Larreur is a PhD student working in the Cooperative Wildlife Research Laboratory at Southern Illinois University. He is co-advised by Dr. Clay Nielsen and Dr. Guillaume Bastille-Rousseau and is researching forest carnivore distributions in southern Illinois. Dr. Clay Nielsen is Professor of Wildlife Ecology and Conservation at the Cooperative Wildlife Research Laboratory at SIU where he has studied Illinois wildlife for 25 years. Dr. Guillaume Bastille-Rousseau is an assistant professor with the Cooperative Wildlife Research Laboratory at SIU. His research focuses on the spatial wildlife ecology of terrestrial species, mostly focusing on animal movement.