Simon R, Brinkmann R, Hochradel K, Mages J, Nagy M, Niermann I, Stiller F, Behr O (2015)
Publication Type: Conference contribution
Publication year: 2015
Event location: Berlin
In Central Europe, acoustic monitoring of bat activity has become the most common method to assess the collision risk of bats at wind turbines. Often, acoustic data are used to develop turbine specific ‘bat friendly’ operational algorithms that reduce the collision risk. A major problem of acoustic monitoring is that there are many different methods (e.g. monitoring at the nacelle vs. at ground level, different microphone setups) and different devices (e.g. bat detectors) used to conduct such acoustic surveys at turbines. As these methods and systems vary in their acoustic properties, the bat activity measured strongly depends on the methods/devices used. Precise estimation of bat activity is crucial to assess the collision risk and to develop suitable algorithms to reduce the risk of bat collisions, but also to avoid needless shutdowns of turbines because of algorithms that are too conservative. Here, we compare different methods and detectors that are being used to assess the acoustic bat activity wind turbines, in particular maintenance requirements, downtimes, acoustic properties, and bat activity level recorded. We did acoustic surveys at the nacelle of 16 wind turbines in 8 wind parks in four geographical regions in Germany in 2012 using different systems simultaneously. We used Anabat SD1 (Titley Scientific), Batcorder 1.0 (ecoObs) and UltraSoundGate (Avisoft Bioacoustics) detectors. In the lab, we also measured the frequency responses and directional sensitivity of the detector microphones. We compared the acoustic activity of bats as presence/absence data for 10-minute-intervalls and found that with the settings we used the relative activity of species and species groups was quite similar for different detectors but for most species or species groups Anabat SD1 and UltraSoundGate recorded bat activity that was twice as high as the activity measured with the Batcorder. This shows that for different detectors different models have to be used to precisely predict risk of collision for the bats and deduce suitable algorithms. We found that the employment of different microphone types with different directional characteristics and the use of various detector settings (i.e. various detection thresholds) are one of the main reasons for different estimations of bat activity. We further discuss detection volumes of detectors deduced from frequency response measurements and methods for a consistent calibration.
APA:
Simon, R., Brinkmann, R., Hochradel, K., Mages, J., Nagy, M., Niermann, I.,... Behr, O. (2015). Acoustic assessment of bat activity at wind turbines: Comparing the performance of different bat detectors. In Proceedings of the Conference on Wind energy and Wildlife Impacts. Berlin.
MLA:
Simon, Ralph, et al. "Acoustic assessment of bat activity at wind turbines: Comparing the performance of different bat detectors." Proceedings of the Conference on Wind energy and Wildlife Impacts, Berlin 2015.
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