Dueling bull moose touch antlers at Isle Royale National Park. (Photo courtesy of the National Park Service/Kelly Morrissey)

ISLE ROYALE — The growing number of people using trails on remote Isle Royale National Park is affecting how some wildlife species behave, according to a new study.

The park saw a 338% increase in visitors after 2020. 

The multi-year study used 156 infrared cameras to monitor four mammals: wolves, moose, snowshoe hare and red fox.

It found that animals tend to avoid humans as visitation increases. It also found that animal activity or behavior during the day would also change with increased human activity.

Mark Romanski works for the National Park Service on Isle Royale. He oversaw the research at the park.

“The interest there is trying to see if we should have any concerns about the level of visitation and what that might mean in terms of the history of these different species,” Romanski said.

According to the study, “A major finding was that species space use and activity patterns were altered only on-trail while remaining constant off-trail. This suggests that the influence of human activity occurs mostly on trails.” 

Hailey Boone, a Ph.D. student in the Michigan State University Department of Fisheries and Wildlife, is the lead author of the study published in the journal Global Ecology and Conservation.  

“It’s a very unique system in that it’s super rare in the natural world to be able to have a system where animals can’t just wander off. Your test subjects can’t go away,” Boone said.

It’s a five-hour boat ride to the island in Lake Superior from the Michigan mainland, she said. Over 99% of the land is a federally designated wilderness.

“This is as close as we can get to a laboratory scenario where we have a little more control,” she said.

Researchers used the low number of visitors during the COVID-19 pandemic, when visit restrictions were in effect, to see how animals responded to low levels of human visitation compared to high levels.

“Even though humans are technically allowed to recreate in the wilderness areas, the fact that they are potentially changing some sort of behavior from animals goes against the (federal Wilderness Act),” Boone said.

The study said, “Reducing visitation during peak seasons or redistributing visitation across a season could reduce mammals’ responses to recreational activity while continuing to provide for public enjoyment.” 

Boone said visitors should go during a “less busy time” which can have less of an impact on how wildlife behaves. 

She said, “Humans might not have that much of an impact” if fewer went to the national park in July — peak season — and visitors were more distributed over the open season.

She said more research is needed to determine how high levels of human activity affect animal behavior.