CHAMPAIGN, Ill., 8/5/20: Asking licensed Illinois trappers about their experiences and the numbers of coyotes and foxes they harvest is one way to discover animal population trends. The trick, though, is to account for trappers’ motivations that can be swayed by economic factors and weather, according to Javan Bauder, post-doctoral researcher at the University of Illinois’ Illinois Natural History Survey.
In a recent study, Bauder and colleagues used trapper questionnaire data from 1976 to 2018 in statistical models to glean information on coyote and red and gray fox populations in Illinois.
They found that, after controlling for confounding factors, such as gas prices and unemployment rates, annual trapper harvest and the number of animals harvested per trapper dwindled over time for red and gray foxes and increased for coyotes. These findings are consistent with what is known about long-term population changes of these species in Illinois.
This information is important to guide state hunting and trapping regulations, study species’ declines, and manage wildlife.
“Understanding the factors that influence trappers’ motivations and behaviors—gas prices, pelt prices, winter unemployment rates, and weather—are a way to statistically control for these variations to get more accurate results,” Bauder said.
Scientists may hypothesize that as gas prices and unemployment rates increase, trappers will be less likely to trap mammals for recreation. Lower pelt prices might also influence trappers’ willingness to trap, but more so in states such as Alaska where many trappers earn a profit. Studies show that Illinois trapping is more of a sport and an opportunity for trappers to spend time outdoors.
Likewise, severe winter weather is believed to cause trappers to stay indoors and foxes and coyotes to be less active.
Interestingly, Bauder found that increased gas prices did not seem to affect fox harvest per trapper. Yet coyote trappers harvested fewer coyotes when gas prices were high. The researchers also found that weather affected red fox harvest, in that the more snowy days, the lower the harvest numbers per person.
As indicated, the significance of each factor varied when pertaining to foxes vs. coyotes.
“There’s no one-size-fits-all strategy for controlling confounding factors across different furbearing species,” Bauder said. “Scientists can’t assume that they know which factors are causing harvest variations.”
Further study is needed to account for additional factors, such as how some species affect the populations of others. Coyotes may prey on red foxes and displace them from rural to urban areas where coyotes are less likely to live, but also where foxes are less accessible to trappers. Numerous variables must be considered to obtain accurate population estimates.
This study was published in the Journal of Wildlife Management and was funded by the Federal Aid in Wildlife Restoration Program.
Media contact: Javan Bauder, 217-300-9561, firstname.lastname@example.org