When we hike, bike or ski through the woods, wildlife often steers clear. But a recent study suggests animals aren’t always spooked by recreators, and the presence of more people doesn't always mean animals are more scared.
The study, published earlier this year in the journal Biological Conservation, is a follow-up to another one from 2024, in which researchers in Wyoming’s Bridger-Teton National Forest set up motion-triggered speakers that played recordings of the sounds of hikers, bikers and other activities. Cameras captured how elk, deer, bears and other animals responded.
In that study, they found that animals were much more likely to exhibit anti-predator behaviors like staying on alert or fleeing after hearing the recreation soundtracks. But there was enough variation to raise additional questions.
Mark Ditmer, a research ecologist with the U.S. Forest Service in Fort Collins, Colorado, said the team wanted to know whether exposure to humans had any effect on the results.
“How likely are animals over here generally acting like they're habituated to humans,” he said, “versus more wildland areas where maybe [humans] might have a bigger impact on wildlife in those areas."
So, in a follow-up analysis, they layered anonymized cell phone data on top of the videos collected to estimate how many people were in different parts of the forest at the time and found that animals in busier spots were less likely to act scared in response to the recreation noises.
“In some areas, humans don't really cause this anti-predator response because some individuals at least no longer fear those encounters as much,” Ditmer said.
In high-use areas of the forest, such as just outside Jackson, Wyoming, animals were 22% less likely to flee, compared to low-use areas. The changes were more dramatic among more sensitive species, like elk.
When elk heard recreation noises near popular trails, they were about 35% less likely to flee compared to more remote parts of the forest.
Ditmer said this could mean that wildlife are growing more accustomed to groups of hikers and bikers, but there could also be other explanations. Perhaps the more sensitive among the critters are moving deeper into the woods.
The results could inform human-wildlife coexistence efforts. For example, land managers could choose to build new trails in areas where recreation is more concentrated and where wildlife already appears more tolerant.
"There might be some areas in the backcountry where you want those animals to remain acting more as if they aren't necessarily interacting with humans all the time," Ditmer said.
This story was produced by the Mountain West News Bureau, a collaboration between Wyoming Public Media, Nevada Public Radio, Boise State Public Radio in Idaho, KUNR in Nevada, KUNC in Colorado and KANW in New Mexico, with support from affiliate stations across the region. Funding for the Mountain West News Bureau is provided in part by the Corporation for Public Broadcasting.
