Even without hunting rifles, humans seem to have a strong negative impact on wildlife movement. A study of hiking trails in Glacier National Park during and after the COVID-19 shutdown adds evidence to the theory that humans can create a “landscape of fear” like other apex predators, changing how a species uses an area once it’s there.
Washington State University and National Park Service researchers found that when two human parks were present, 16 of 22 mammalian species, including predators and prey alike, changed where and when they accessed the areas. Some completely deserted places they used previously, others used them less frequently, and some turned to more nocturnal activities to avoid humans.
said Daniel Thornton, a wildlife ecologist at WSU and senior author of the study website published in the journal Scientific reports. “The surprising thing is that there is no other real human disturbance because Glacier is a very protected national park, so these responses are really driven by human presence and human noise.”
The researchers also expected to find an effect known as “human protection,” when human presence causes large predators to avoid an area, providing the opportunity for smaller predators and possibly some prey species to use an area more frequently. In this case, they only found this possible effect for one species, the red fox. Foxes were more present on and near trails when the park was open—perhaps because their rivals, the coyotes, avoided those areas when humans were around.
Several species showed reduced use of trail areas when the park was open, including black bear, elk, and white-tailed deer. Many reduced their daily activities, including mule deer, snowshoe hare, grizzly bears, and wolves. A few, including the cougars, seemed indifferent to the human presence.
While the effect of low-impact recreation is concerning, the researchers stressed that more research is needed to determine whether it has negative effects on species survival.
“This study doesn’t say that hiking is necessarily harmful to wildlife, but it does have some effects on spatiotemporal ecology, or how and when wildlife uses landscapes,” said Alyssa Anderson, WSU master’s graduate and first author of the study. “Maybe they’re not on the trails as much, but they’re using different places, and how much does that actually affect the species’ ability to survive and thrive in a place, or not? There are a lot of questions about how that actually plays a role in population survival.”
The study came about in part because of the pandemic. Both humans and wildlife love to use the trails, so researchers set up a set of camera traps near several trails to study lynx populations in Glacier National Park when COVID-19 hit. In an effort to prevent the virus from spreading to the nearby Blackfeet Indian Reservation, the eastern part of the park was closed in 2020 with minimal access allowed to officials and researchers.
This allowed Anderson, Thornton, and co-author John Waller of Glacier National Park to conduct a naturalistic experiment. They took pictures in the summer of 2020 when the park was closed and also in 2021 when it opened again.
Glacier, which covers nearly 1,600 square miles of northwestern Montana, receives more than 3 million human visitors annually. It is also home to a wide variety of animals with almost the entire range of mammal species that have been present in the area historically.
Thornton said park managers face a balancing act between conservation and public use tasks.
“Obviously it’s important for people to be able to get out there, but there may be a level that starts to cause problems,” he said. “Some additional research might help get a better understanding of that and help develop some guidelines and goals.”
This study received support from the Glacier National Park Conservancy and the United States Department of Agriculture.