WHAT THE EVIDENCE SAYS
At 12 sites over two field seasons, researchers broadcast motorized and non-motorized recreation sounds at high- and low-use rates and compared weekly mammal detections with nature-sound controls. Under high-rate motorized playback, every analyzed species except mule deer remained below baseline through the 15-week season; mule deer returned by week six. High-rate non-motorized effects persisted to about seven weeks for other species, while low-rate non-motorized treatments produced seven- to nine-week recovery times.
WHY IT MATTERS / OUR READ
For managers, temporal pattern is part of recreation intensity. A trail can be quiet today and still sit inside a wildlife-response window created by repeated prior use. Where sensitive species and high-use routes overlap, spatial refugia, seasonal limits or use-rate management may matter more than a simple open/closed designation.
CAVEATS / UNCERTAINTY
The experiment isolated acoustic disturbance rather than the full package of people, vehicles, scent and physical trail use. Camera detections measure use or avoidance, not demographic harm, and the 12-site Wyoming experiment should not be converted into universal recovery periods for other species or landscapes.
SOURCE
Biological Conservation / USFS — primary study
View original evidence ↗