Providing outdoor recreational opportunities to people and protecting wildlife are dual goals of many land managers. However, recreation is associated with negative effects on wildlife, ranging from increased stress hormones1,2 to shifts in habitat use3,4,5 to lowered reproductive success.6,7 Noise from recreational activities can be far reaching and have similar negative effects on wildlife, yet the impacts of these auditory encounters are less studied and are often unobservable. We designed a field-based experiment to both isolate and quantify the effects of recreation noise on several mammal species and test the effects of different recreation types and group sizes. Animals entering our sampling arrays triggered cameras to record video and broadcast recreation noise from speakers ∼20 m away. Our design allowed us to observe and classify behaviors of wildlife as they were exposed to acoustic stimuli. We found wildlife were 3.1–4.7 times more likely to flee and were vigilant for 2.2–3.0 times longer upon hearing recreation noise compared with controls (natural sounds and no noise). Wildlife abundance at our sampling arrays was 1.5 times lower the week following recreation noise deployments. Noise from larger groups of vocal hikers and mountain bikers caused the highest probability of fleeing (6–8 times more likely to flee). Elk were the most sensitive species to recreation noise, and large carnivores were the least sensitive. Our findings indicate that recreation noise alone caused anti-predator responses in wildlife, and as outdoor recreation continues to increase in popularity and geographic extent,8,9 noise from recreation may result in degraded or indirect wildlife habitat loss. Display omitted •Noise from human recreation may have far-reaching effects on wildlife•We experimentally tested the effect of human recreation noises on wildlife•Recreation noise, without any human presence, caused anti-predator responses•Species’ sensitivity varied, but large vocal groups caused the strongest responses Noise from recreational activities can be far reaching and have negative effects on wildlife, yet the impacts of these auditory encounters are often unobservable. Zeller et al. design an experiment to isolate the effect of recreation noise and test recreation type, group size, and vocalization presence on terrestrial wildlife.