Wildlife responses to recreation noise
Land management agencies are tasked with providing recreation opportunities while also protecting wildlife habitat from undue human disturbance. With more people hiking, biking, and using off-road vehicles, there is an urgent need to understand the effects of recreation on wildlife - and particularly the effects of noise from these activities - because sounds can extend far beyond trails and roads into surrounding ecosystems.
Background
Outdoor recreation can cause negative impacts on wildlife such as increased stress levels, behavioral responses such as vigilance and fleeing, and longer-term responses such as avoidance of recreation hotspots. Fewer species may remain in areas with substantial recreation, causing shifts in animal communities.
Because wildlife often hear sounds of hikers, bikers, or off-highway vehicle (OHV) motors before observing them, and due to the permeating spread of noise through the landscape, the effects of recreation noise may be far-reaching. However, until now, wildlife responses to these sounds alone have been unobservable.
Our study combines an experimental design with new technologies to observe wildlife responses to recreation noise. We used an audio playback system to play real sounds of different recreation types (hikers, mountain bikers, trail runners, OHV users), group sizes, and recreationist behaviors (whether the recreationists were talking or not). We paired audio playbacks with camera traps that recorded videos of how wildlife responded to the recreation noise, without the actual presence of recreationists.
By testing different recreation types, group sizes, and other attributes, we can quantify which aspects of recreation noise affect wildlife, thereby providing critical information for recreation managers.
Objectives
Identify the immediate behavioral responses of wildlife to recreation noise;
Determine which species are more tolerant or sensitive to recreation noise;
Investigate whether wildlife avoid areas with recreation noise at certain times or distances;
Understand community-level responses to recreation noise.
Study area and sampling design
Our research is conducted on the Bridger-Teton National Forest in Wyoming, U.S., which is home to a high abundance and diversity of wildlife and a range of outdoor recreation types and intensities.
We devised an experiment designed to expose wildlife to the pre-recorded recreation noise treatments and quantify their responses without the need for a person to be present. Noise treatment recordings consisted of recreationists of large, medium, and small group sizes engaged in hiking, mountain biking, trail running, and OHV use. We created one sampling strategy for mammals and one for birds.
To study birds, we programmed our audio-playback devices to play recreation sound once per hour and recorded bird songs both prior to and after the recreation sound was played. These data are being used to determine changes in the presence of bird species in response to recreation noise.
To study mammals, we placed motion-sensitive trail cameras on game trails along with devices that played programmed recreation sound when an animal triggered the camera. We recorded continuous video of the animal’s responses, which we classified into different behaviors. We also used the data to determine changes in site use in response to recreation noise.
Study area diagram
Experimental recreationist noise alters behavior and space use of wildlife
Our first paper from this long-term research project was published in Current Biology in spring of 2024. This paper found that the sounds people generate during outdoor recreation activities cause strong anti-predator responses in wildlife, even in the absence of actual humans.
Our work showed that wildlife were far more likely to flee and were vigilant for longer after hearing recreation noise than after hearing natural sounds or no noise. Elk were the most sensitive species to recreation noise, and large carnivores were the least sensitive. Additionally, local relative abundance of wildlife was slightly lower the week following recreation noise deployments.
Noise from larger groups of vocal hikers and mountain bikers caused the highest probability of fleeing. Interestingly, we found that noise associated with different recreation types (e.g. hiking, mountain biking, or OHV driving) may not be as important a driver of wildlife fleeing or vigilance as group sizes or group vocalization behavior (i.e. chattiness).
Ultimately, as outdoor recreation continues to increase in popularity and geographic extent, this research suggests that noise from recreation may result in degraded wildlife habitat or indirect habitat loss.
Video compilation of wildlife responses to recreation noise
Below, we have included a compilation of short video clips depicting some of the responses of different wildlife species to recreation noise that we observed during our study. The wildlife pictured in these clips include a black bear, elk, a mountain lion, mule deer, and a wolf.
Ongoing research
This research is currently in progress, as we aim to answer many additional questions about the effects of recreation noise on wildlife. We will post results of additional studies here as they are published. In the meantime, please reach out to Dr. Kathy Zeller or Dr. Mark Ditmer with questions and media inquiries.
Publications
- Katherine Zeller, Mark Ditmer, John R. Squires, William L. Rice, James Wilder, Don DeLong, Ashley Egan, Niah Pennington, Chris A. Wang, Jacinta Plucinski, Jesse R. Barber. 2024. Experimental recreationist noise alters behavior and space use of wildlife
Rocky Mountain Research Station Scientists
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Person
Katherine Zeller, PhD
Research Biologisthttps://research.fs.usda.gov/about/people/katherine.zeller -
Person
Mark Ditmer, PhD
Research Ecologisthttps://research.fs.usda.gov/about/people/mark.ditmer -
Person
John R. Squires, PhD
Research Wildlife Biologisthttps://research.fs.usda.gov/about/people/john.squires
Collaborators
Kathy Zeller - Aldo Leopold Wilderness Research Institute and the USDA Forest Service Rocky Mountain Research Station
Mark Ditmer - USDA Forest Service Rocky Mountain Research Station
John Squires - USDA Forest Service Rocky Mountain Research Station
William L. Rice - Parks, Tourism, and Recreation Management Program, University of Montana
James Wilder - USDA Forest Service, Bridger-Teton National Forest
Don DeLong - USDA Forest Service, Bridger-Teton National Forest
Ashley Egan - USDA Forest Service, Bridger-Teton National Forest
Niah Pennington - Warner College of Natural Resources, Colorado State University
Chris A. Wang - Freaklabs
Jacinta Plucinski - Freaklabs
Jesse R. Barber - Department of Biological Sciences, Boise State University
Related Programs
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Program
https://research.fs.usda.gov/rmrs/programs/aldoleopoldStation -
Program
https://research.fs.usda.gov/rmrs/programs/wildlife-ecologyStation