EFFECTS OF WIND ON THE BEHAVIOR AND CALL TRANSMISSION OF PIKAS (OCHOTONA PRINCEPS)

It has been suggested that pikas are less active during inclement weather. We hypothesized that this decrease in activity is a predator-avoidance response to wind conditions that decrease the effectiveness of the alarm calls of pikas. We examined this hypothesis by broadcasting and rerecording the prominent frequencies (900-5,500 Hz) of pikas' calls and by observing behavior of focal pikas during varying weather conditions. Both attenuation of pure tones and the amount of wind noise increased significantly as wind speed increased. Additionally, wind direction created asymmetrical patterns of attenuation of pure tones, potentially distorting and degrading the call. Further, pikas spent significantly more time inactive at higher wind speeds, with nonvigilant active behaviors decreasing at a higher rate than vigilant active behaviors. Examination of these data supports the hypothesis and suggests that wind influences the behavior of animals that rely on alarm calls.