Varying behavioral responses of wildlife to motorcycle traffic

Abstract

Roads are a pervasive feature across the U.S., and traffic and its associated noise has significant impacts on wildlife. However, we know little about the effect of motorcycle traffic and the potential for prolonged response of animals to loud and periodic traffic disturbances. We studied the behavioral response of multiple species in Devils Tower National Monument to the Sturgis Motorcycle Rally, which raised median A-weighted sound levels by more than 20 dB for 7 days. Different taxa demonstrated different responses to the event, which we categorized into three different patterns of behavioral shifts: weak evidence of a response, temporary response during the rally, and a sustained response that lasted after the rally. We found little evidence that western wood-pewee (Contopus sordidulus) vocal activity, our behavioral metric, was affected by the rally. Activity patterns of white-tailed deer (Odocoileus virginianus) and black-tailed prairie dogs (Cynomys ludovicianus) shifted during the rally, and deer reverted to pre-rally activity patterns when motorcycle activity declined. The diversity of bat species active was also lower during the rally, and the diversity of species active remained low several weeks after the rally. Our observations suggest that most species shifted their behavior to avoid motorcycle traffic but the ability to return to pre-disturbance behavioral patterns varied. Examining responses to traffic activity and noise across a broad array of species can identify relative sensitivity to such disturbances and infer community-level impacts, helping to inform strategies to reduce effects or plan for recovery.