Animals in National Parks Are Affected by Even a Few Visitors

When there are crowds of tourists at Yellowstone or Yosemite, it’s easy to see why that would have an impact on wildlife. Throngs of people jockeying to see natural wonders or hiking through trails can make animals keep a low profile. But a new study finds that even in remote national parks with very few visitors, just the presence of a few people can have an impact on the activity of the animals who live there.

Researchers first looked into the behaviors when managers of Glacier Bay National Park in Alaska created new management plans in 2016 because they worried about the impact of visitors. Areas of the park were either designated as “high impact,” where there was a strong concentration of outdoor recreation and human activity, or “low impact,” where activity was restricted.

The park only has about 40,000 tourists who visit via land each year, which makes it a good choice to study how wildlife responds to little human activity. (By contrast, Great Smoky Mountains National Park has 14.1 million annual visitors and Yellowstone has 4.9 million.)

Researchers were able to use the changes in the park to study how wildlife would respond to the higher levels of human activity in certain areas and lower levels in others.

“For me personally, after visiting Glacier Bay for the first time, it became immediately clear how special it is. When you leave the frontcountry areas of the park you can go days without seeing another person, and I've had some pretty incredible wildlife experiences there,” lead author Mira Sytsma, who completed this study as a University of Washington graduate student, tells Treehugger.

“Those experiences made this work that much more interesting and made the opportunity to inform management decisions for the park that much more significant.” 

Midday Activity

For their study, researchers used camera traps to monitor brown bears, black bears, wolves, and moose over two summers. They compared the presence of animals in parts of the park where there was a lot of human activity to areas where human activity was restricted.

They found that nearly any human activity at all had an impact on wildlife behavior. They didn’t record more than five photos each week of any of the four species, unless there were no humans around.

“I wasn't necessarily surprised that wildlife responded to outdoor recreation—this has been established in many other studies—but what surprised me was the level of human activity that led to this wildlife response,” Sytsma says.

“Outdoor recreation in Glacier Bay is very low compared to other national parks, and we showed in this study that even those very low levels of human activity can change how wildlife use the space they occupy and their patterns of activity throughout the day.”

The four species they studied reacted differently to human presence. Moose, for example, changed their activity patterns throughout the day to match when people were most active, around midday.

“This potentially indicates that they were using human presence as a temporal ‘shield’ during the day, essentially leveraging the fact that predators were avoiding humans during that time,” Sytsma says.

Wolves, however, shifted their activity to be more active when humans were not around. Wolf activity was almost non-existent around midday.

The findings were published in the journal People and Nature.

Threshold of Human Activity

Researchers expect that similar wildlife responses could be found at parks that have few visitors and low levels of outdoor recreation.

“Parks that have much higher visitation rates may have already passed a ‘threshold’ of human activity where wildlife begin to change their behavior. In other words, wildlife may be used to human activity in these areas, which may make detecting a change in wildlife behavior trickier,” Sytsma says.

“I'd be curious to see if other species responded similarly—we looked only at large mammals, and it would be interesting to understand how smaller species respond to human activity in these protected areas.”