Plateau pikas near roads are bold and silent when facing a potential predator.

Abstract

Human disturbance, particularly road traffic, is one of the greatest threats to wildlife. Considering the association between alerting behavior and the survival of animals, it is important to study the effects of road traffic on alerting behavior of wildlife. Previous studies assessing the short-term impact of road traffic on alerting behavior of wildlife have focused on vigilance distances. However, studies on the use of alarm calls are scarce, and it is unclear whether such behavioral responses change after repeated exposure to road traffic. We assessed the alerting behavior of plateau pikas (Ochotona curzoniae) who were near or far from roads when facing a potential predator. We found that pikas near roads exhibited shorter vigilance and tolerance distances, and produced fewer alarm calls than those relatively far away from roads. Furthermore, both vigilance and tolerance distances of plateau pikas were significantly positively correlated with the distance from the burrow to the road. Road traffic reduced antipredator responses and shaped alerting behavior; that is, pikas near roads were bolder and more silent compared to those far away from roads. Our findings suggest that increasing urbanization will have corresponding effects on animal behavior, which may have significant fitness effects in the future.