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Wind energy facilities are constructed without full knowledge of their effects on birds, and the noise generated by wind turbines is a particular concern. I investigated the effects of wind turbine noise on male Greater Prairie-Chicken (Tympanuchus cupido pinnatus) vocalizations and chorus near Ainsworth, NE, USA in 2013 and 2014. I studied 14 leks located in the area surrounding a 36-turbine wind energy facility. I used two main approaches in this study. First, I recorded Greater Prairie-Chicken boom, cackle, whine, and whoop vocalizations at each of the study leks and measured the duration, sound pressure level, peak frequency, dominant frequency, fundamental frequency, bandwidth and nonlinearities of each vocalization. I used linear models to determine whether the vocalizations at leks near the wind energy facility differed from vocalizations at leks farther away. I found that within 1000 meters of the wind energy facility, boom and whoop sound pressure levels were higher, boom duration was shorter, whine fundamental frequency was higher, and cackle biphonations occurred less often. These differences suggest that male Greater Prairie-Chickens are adjusting aspects of their vocalizations in response to wind turbine noise. In the second approach, I placed audio recorders along transects extending from leks to record the sound of the Greater Prairie-Chicken chorus. I also placed audio recorders at locations in a grid formation overlaid on the wind energy facility. I created models to describe how the chorus and wind turbine noise were affected by covariates. I used the models to predict levels of the chorus and wind turbine noise and assess the potential for wind turbine noise to mask the chorus under specific scenarios. The results suggested that wind turbine noise may have the potential to mask the Greater Prairie-Chicken chorus at 296Hz under these scenarios, but the extent and degree of masking is uncertain. Many factors, including the accuracy of the masking threshold, variation in signal detection, and characteristics of the chorus, may affect the masking assessment.
Advisors: Larkin A. Powell and Mary Bomberger Brown
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