Ultrasonic Deterrents To Reduce Bat Mortality at Wind Turbines—Short Science Summary

Bats

In North America, several bat species commonly collide with operating turbines. Although the ultimate cause of collisions is unknown, studies suggest bats may be attracted to turbines because they often approach turbine structures and spend extended periods of time (seconds to minutes) near them. To reduce bat mortality at wind farms, operators seek to reduce the amount of time bats spend near spinning turbine blades (known as exposure). Current approaches to reduce exposure include both curtailment, in which turbine operators stop turbine rotors from spinning during periods when bats are expected to be at the highest risk of collision, and deterrent technologies that seek to discourage bats from entering the rotor-swept area or at least limit the amount of time spent there.

The use of ultrasonic deterrent devices that emit one or more high-frequency sounds has been the most tested technique. The idea behind using ultrasound as a deterrent is it disrupts the ability of bats to effectively echolocate (sometimes referred to as signal jamming). According to this idea, introducing ultrasonic noise in the environment in the same frequency ranges that bats use to echolocate makes it difficult for bats to reliably interpret their own ultrasonic vocalizations. Bats are expected to vacate environments where echolocation is required but becomes unreliable. To test this hypothesis, researchers have investigated the behavioral responses of bats in laboratory (Spanjer 2006) and natural settings (Szewczak and Arnett 2007; Gilmour et al. 2020; Fritts et al. 2024).

In one of the earliest studies on the topic, Szewczak and Arnett (2007) used ultrasonic deterrents at a natural pond that bats frequented for drinking and foraging. Szewczak and Arnett demonstrated that ultrasonic deterrents greatly reduced the overall bat activity rates within a distance of approximately 20 meters (m). Despite relatively consistent results using ultrasound deterrents in natural settings (Szewczak and Arnett 2007; Gilmour et al. 2020) and as a tool to discourage bats (at least temporarily) from approaching buildings and bridges (Zeale et al. 2016; Aldemir Bektas et al. 2022), researchers’ ability to reduce bat mortality rates around wind turbines has been inconsistent (Table 1). For example, Weaver et al. (2020) found that ultrasonic deterrents reduced hoary bat (Lasiurus cinereus) and Brazilian free-tailed bat (Tadarida brasiliensis) fatalities but found no difference in the number of northern yellow bat (Lasiurus intermedius) carcasses between turbines with and without ultrasonic deterrents. Despite overall reductions in bat fatalities, several studies reported increased fatalities when considering species-specific effects.

The table below contains the literature relevant to this summary document and will continue to be updated as new literature is added to Tethys.

Title Author Date Content Type Technology Stressor Receptor
Peaks in bat activity at turbines and the implications for mitigating the impact of wind energy developments on bats Richardson, S., Lintott, P., Hosken, D., Economou, T., Mathews, F. Journal Article Wind Energy, Land-Based Wind Attraction, Avoidance, Collision Bats
Calculation of biodiversity level between different land-uses to improve conservation outcomes of biodiversity offsetting Millon, L., Barre, K., Julliard, R., Compère, P., Kerbiriou, C. Journal Article Wind Energy, Land-Based Wind Collision Bats, Birds
Bats Flying at High Altitudes McCracken, G., Lee, Y., Gillam, E., Frick, W., Krauel, J. Book Chapter Wind Energy, Land-Based Wind Collision Bats
Passive Ultrasonic Deterrents to Reduce Bat Mortality in Wind Farms Sharma, A. Presentation Wind Energy, Land-Based Wind, Fixed Offshore Wind, Floating Offshore Wind Collision Bats
Estimating bat fatality at a Texas wind energy facility: implications transcending the United States–Mexico border Weaver, S., Jones, A., Hein, C., Castro-Arellano, I. Journal Article Wind Energy, Land-Based Wind Collision Bats
Local trends in abundance of migratory bats across 20 years Green, D., McGuire, L., Vanderwel, M., Willis, C., Noakes, M., Bohn, S., Green, E., Brigham, R. Journal Article Wind Energy, Land-Based Wind Collision Bats, Environmental Impact Assessment
Ultrasonic acoustic deterrents significantly reduce bat fatalities at wind turbines Weaver, S., Hein, C., Simpson, T., Evans, J., Castro-Arellano, I. Journal Article Wind Energy, Land-Based Wind Collision Bats
AWWI Technical Report: 2nd Edition: Summary of Bat Fatality Monitoring Data Contained in AWWIC Allison, T., Butryn, R. Report Wind Energy, Land-Based Wind Collision Bats
Enabling Renewable Energy While Protecting Wildlife: An Ecological Risk-Based Approach to Wind Energy Development Using Ecosystem-Based Management Values Copping, A., Gorton, A., May, R., Bennet, F., DeGeorge, E., Goncalves, M., Rumes, B. Journal Article Wind Energy, Land-Based Wind, Fixed Offshore Wind, Floating Offshore Wind Collision, Habitat Change Bats, Birds, Fish, Marine Mammals, Human Dimensions, Social & Economic Data, Stakeholder Engagement
Comparing methods to estimate the proportion of turbine-induced bird and bat mortality in the search area under a road and pad search protocol Maurer, J., Huso, M., Dalthorp, D., Madsen, L., Fuentes, C. Journal Article Wind Energy, Land-Based Wind Collision Bats, Birds
Transcontinental 2200 km migration of a Nathusius’ pipistrelle (Pipistrellus nathusii) across Europe Alcalde, J., Jiménez, M., Brila, I., Vintulis, V., Voigt, C., Petersons, G. Journal Article Wind Energy, Land-Based Wind Collision Bats
Factors affecting carcass detection at wind farms using dogs and human searchers del Valle, J., Peralta, F., Arjona, M. Journal Article Wind Energy, Land-Based Wind Collision Bats, Birds
Evidenzbasierter Fledermausschutz in Windkraftvorhaben Voigt, C. Book Wind Energy, Land-Based Wind Collision Bats
An evaluation of bird and bat mortality at wind turbines in the Northeastern United States Choi, D., Wittig, T., Kluever, B. Journal Article Wind Energy, Land-Based Wind Collision Bats, Birds
Testing and Evaluation of "SafeWind" A Bird Protection System Soni, B., Loske, K., Lackmann, J. Report Wind Energy, Land-Based Wind, Fixed Offshore Wind, Floating Offshore Wind Collision Bats, Birds
Dogs detect larger wind energy effects on bats and birds Smallwood, K., Bell, D., Standish, S. Journal Article Wind Energy, Land-Based Wind Collision Bats, Birds
Bat Activity Rates do not Predict Bat Fatality Rates at Wind Energy Facilities Solick, D., Pham, D., Nasman, K., Bay, K. Journal Article Wind Energy, Land-Based Wind Collision Bats
Landscape Factors Associated with Fatalities of Migratory Tree-Roosting Bats at Wind Energy Facilities: An Initial Assessment Peters, K., Evans, I., Traiger, E., Collins, J., Mathews, C., Klehr, A. Report Wind Energy, Land-Based Wind Collision Bats
South African Bat Fatality Threshold Guidelines: Edition 3 MacEwan, K., Aronson, J., Richardson, K., Taylor, P., Coverdale, B., Jacobs, D., Leeuwner, L., Marais, W., Richards, L. Guidance Wind Energy, Land-Based Wind Collision Bats
Population-Level Risk to Hoary Bats Amid Continued Wind Energy Development: Assessing Fatality Reduction Targets Under Broad Uncertainty Electric Power Research Institute (EPRI) Report Wind Energy, Land-Based Wind Collision Bats
Post -Construction Monitoring Studies for the Headwaters Wind Farm Randolph County, Indiana Rodriguez, M., Tredennick, A., DuBridge, K. Report Wind Energy, Land-Based Wind Collision Bats
Assessing population‐level consequences of anthropogenic stressors for terrestrial wildlife Katzner, T., Braham, M., Conkling, T., Diffendorfer, J., Duerr, A., Loss, S., Nelson, D., Vander Zanden, H., Yee, J. Journal Article Wind Energy, Land-Based Wind Collision Bats, Birds
Learning from Real-World Experience to Understand Renewable Energy Impacts to Wildlife Conkling, T., Vander Zanden, H., Poessel, S., Loss, S., Allison, T., Diffendorfer, J., Duerr, A., Nelson, D., Yee, J., Katzner, T. Report Wind Energy, Land-Based Wind Collision Bats, Birds
Evaluating the Effectiveness of an Ultrasonic Acoustic Deterrent in Reducing Bat Fatalities at Wind Energy Facilities - Final Technical Report Schirmacher, M. Report Wind Energy, Land-Based Wind Collision Bats
Effects of Wind Turbine Curtailment on Bird and Bat Fatalities Smallwood, K., Bell, D. Journal Article Wind Energy, Land-Based Wind Collision Bats, Birds
Relating Bat Passage Rates to Wind Turbine Fatalities Smallwood, K., Bell, D. Journal Article Wind Energy, Land-Based Wind Collision Bats
Estimates of aerial vertebrate mortality at wind farms in a bird migration corridor and bat diversity hotspot Cabrera-Cruz, S., Cervantes-Pasqualli, J., Franquesa-Soler, M., Munoz-Jimenez, O., Rodriguez-Aguilar, G., Villegas-Patraca, R. Journal Article Wind Energy, Land-Based Wind Collision Bats, Birds
European free–tailed bat fatalities at wind farms in southern Spain Muñoz, A., Farfan, M. Journal Article Wind Energy, Land-Based Wind Collision Bats
Long-term Acoustic Assessment of Bats at Spion Kop Reservoir, Montana for 2015-2017 Bachen, D., Burkholder, B., Maxell, B. Report Wind Energy, Land-Based Wind Collision, Displacement Bats
Evaluation of an Acoustic Deterrent to Reduce Bat Mortalities at an Illinois Wind Farm Romano, W., Skalski, J., Townsend, R., Kinzie, K., Coppinger, K., Miller, M. Journal Article Wind Energy, Land-Based Wind Collision Bats
Influence of landscape and time of year on bat-wind turbines collision risks Roemer, C., Bas, Y., Disca, T., Coulon, A. Journal Article Wind Energy, Land-Based Wind Attraction, Avoidance, Collision Bats
Impacts to Wildlife of Wind Energy Siting and Operation in the United States Allison, T., Diffendorfer, J., Baerwald, E., Beston, J., Drake, D., Hale, A., Hein, C., Huso, M., Loss, S., Lovich, J., Strickland, M., Williams, K., Winder, V. Report Wind Energy, Land-Based Wind, Fixed Offshore Wind Attraction, Avoidance, Collision, Displacement, Habitat Change Bats, Birds
Understanding Wind Energy Impacts to Bats and Testing Reduction Strategies in South Texas Weaver, S. Thesis Wind Energy, Land-Based Wind Collision Bats
Red bat fatality: Geographic extents through deuterium and niche models Murtaugh, R., Capparella, A., Kostelnick, J., Johnson, G. Journal Article Wind Energy, Land-Based Wind Collision Bats
A Methodology to Assess the National and Regional Impacts of U.S. Wind Energy Development on Birds and Bats Diffendorfer, J., Beston, J., Merrill, M., Stanton, J., Corum, M., Loss, S., Thogmartin, W., Johnson, D., Erickson, R., Heist, K. Report Wind Energy, Land-Based Wind Collision Bats, Birds
2018 Post - Construction Monitoring Study Black Oak Getty Wind Project Stearns County, Minnesota Pickle, J., Lombardi, J., Stucker, J., DiDonato, G. Report Wind Energy, Land-Based Wind Collision Bats, Birds
2018 Post-Construction Monitoring Study Red Pine Wind Energy Facility Lincoln County, Minnesota Trana, M., Hyzy, B., Pickle, J., Gustafson, Z. Report Wind Energy, Land-Based Wind Collision Bats, Birds
New Creek Wind Project 2018 Post-construction Monitoring Stantec Consulting Report Wind Energy, Land-Based Wind Collision Bats, Birds
GenEst Statistical Models — A Generalized Estimator of Mortality Dalthorp, D., Madsen, L., Huso, M., Rabie, P., Wolpert, R., Studyvin, J., Simonis, J., Mintz, J. Book Chapter Wind Energy, Land-Based Wind Collision Bats, Birds
Carcass Age and Searcher Identity Affect Morphological Assessment of Sex of Bats Nelson, D., Nagel, J., Trott, R., Campbell, C., Pruitt, L., Good, R., Iskali, G., Gugger, P. Journal Article Wind Energy, Land-Based Wind Collision Bats
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