According to a new study, even in remote, rarely visited national parks, the presence of even a few humans has an impact on the activity of wildlife that lives there. The study discovered that nearly any level of human activity in a protected area, such as a national park, can alter the behavior of the animals there. People frequently visit national parks in the United States to see wildlife. But what effect does our presence have on the animals we hope to see?
Over the last decade, national park traffic has steadily increased, and popular parks such as Yosemite and Yellowstone can easily see over a million visitors per year. Animals in these high-traffic areas may alter their behavior to avoid humans.
However, a new study led by the University of Washington discovered that even in remote, rarely visited national parks, the presence of even a few humans has an impact on the activity of wildlife that lives there. The study discovered that nearly any level of human activity in a protected area, such as a national park, can alter the behavior of the animals there. The findings were reported in the journal People and Nature.
“There’s been growing recognition of how much just the presence of humans in these places, and our recreation there, can impact wildlife,” said senior author Laura Prugh, an associate professor in the University of Washington’s School of Environmental and Forest Sciences. “These findings are striking in that they demonstrate that any level of human activity can have an impact on wildlife.”
Our findings lend support to concentrating human activities in some areas. If you’re going to go above zero human activity and it’s going to have an impact, you might as well go way above zero in some areas and have other areas with almost no human activity. Wildlife can then live their natural lives unaffected by people in those areas.
Laura Prugh
The research team based its study in Glacier Bay National Park, a coastal area in southeast Alaska that is accessible only by boat or plane. Most visitors arrive on cruise ships, but the boats don’t dock on shore, and the park has very little human foot traffic. Because so few people visit each year — only about 40,000 but increasing — the park was an ideal place to locate this study, Prugh explained.
“Glacier Bay is a great park to explore what the lower limits are where humans start to affect wildlife behavior,” Prugh said.
The researchers collaborated with national park staff to design and carry out an experiment that compared wildlife activity in areas frequented by humans to areas where people were not present. Over two summers, they installed 40 motion-activated cameras in ten locations to detect people and four animal species: wolves, black bears, brown bears, and moose. The researchers identified two important thresholds by controlling where and when people could access certain areas of Glacier Bay and then measuring wildlife responses to different levels of human activity.
First, if humans were present in an area, the cameras detected fewer than five animals per week across all four species studied. In most cases, this likely meant that animals avoided areas where humans were present. Second, in backcountry areas, wildlife detections dropped to zero each week once outdoor recreation levels reached the equivalent of about 40 visitors per week.
The researchers were surprised by the apparent low tolerance wildlife had for the presence of people nearby.
“It was eye-opening to see the number of wildlife sightings we are ‘missing’ just by recreating in backcountry areas of Glacier Bay,” said lead author Mira Sytsma, who completed this work as a UW graduate student. “I was surprised that for all four species, wildlife detections were always highest when there wasn’t any human activity. So many people visit national parks for the chance to view wildlife, and that desire alone may reduce the chance of it happening.”
Though all four species showed some change in activity due to humans, wolves were most likely to disappear from cameras when people were around. Brown bears were the least impacted by human presence. Moose, however, were more active during the times of day and locations where people were seen. The researchers hypothesize that moose might be using humans as a protective shield from predators, opting to align their active hours with humans to avoid becoming prey.
The researchers expect that in parks where animals are more accustomed to seeing people, at least some individual animals won’t react as strongly to humans as in Glacier Bay. But the findings do shed light on a reality that’s likely playing out at national parks and wilderness areas across the country: More people are visiting these areas than ever before, and the presence of humans is almost certainly impacting the behavior of animals that live there.
“I expect that similar results could be found in other national parks, particularly those with relatively low visitation. I wouldn’t be surprised if more and more people seek out less popular national parks to explore, which will have interesting and important implications for park management and wildlife,” Sytsma said.
National parks and wilderness areas aren’t just seeing more visitors during the high season. More people are opting to use the trail systems during less-busy times to avoid crowds. Additionally, some parks are expanding their trail networks to accommodate more visitors.
The authors hope that this study will encourage park managers to consider new approaches to making parks more accessible to both humans and animals. Managers could, for example, consider concentrating trails and human use in specific areas to reduce their overall footprint, or limit the time of year or days when people can visit.
“Our findings lend support to concentrating human activities in some areas,” Prugh said. “If you’re going to go above zero human activity and it’s going to have an impact, you might as well go way above zero in some areas and have other areas with almost no human activity.” “Wildlife can then live their natural lives unaffected by people in those areas.”
