Human noise drives animals to flee: US Forest Service

Recreational noise may be disrupting the behaviour of animals like elks and black bears in national parks frequented by humans, the US Department of Agriculture’s Forest Service says.

According to the USDA, wildlife studied in Bridger-Teton National Forest in Wyoming demonstrated fear responses when exposed to noise simulating the presence of humans.

Cameras mounted in the study boundary were able to capture the responses of the mammals when they triggered nearby speakers to play a noise. These noises were varied to simulate different group sizes, noises and types of activity, like hiking, cycling or vehicle use.

Based on their observations, USDA found that mammals were at least 3 times more likely to flee the study area when exposed to noise. Study areas also showed 1.5 times less relative animal abundance in the area.

Perhaps unsurprisingly, noise simulating large groups was 6-8 times more likely to drive animals away.

“Wildlife responses to recreation noise are often unobservable,” says Kathy Zeller, a research biologist at the Forest Service. “Our study is the first to quantify responses to human-produced recreation noise based on recreation type, group size, group vocalizations, and wildlife species.

“Information like this can help managers balance recreation opportunities with wildlife management, which is critical as outdoor recreation continues to grow in popularity.”

Black bears and elks were found to be the most affected by the simulation, while large carnivores were reportedly least affected.

“Our findings highlight the need for thoughtful planning, with potential consideration of noise mitigation measures to minimise the impact on wildlife while still providing outdoor recreational opportunities for people,” says Rocky Mountain Research Station ecologist Mark Ditmer “Noise from recreation can carry far beyond a trail system, so understanding how noise alone can affect wildlife is important for management.”

The research is published in the journal Current Biology.