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
A New Stochastic Dynamic Tool to Improve the Accuracy of Mortality Estimates for Bats Killed at Wind Farms Bastos, R., Santos, M., Cabral, J. Journal Article Wind Energy, Land-Based Wind Collision Bats
Reducing Bat Fatalities From Interactions with Operating Wind Turbines (Fact Sheet) Lawson, M. Report Wind Energy, Land-Based Wind Collision, Habitat Change Bats
Reducing Bat Fatalities from Interactions with Operating Wind Turbines National Wind Technology Center Report Wind Energy, Land-Based Wind Collision Bats
Bat Resources Reports for Beech Ridge Wind Energy Project US Fish and Wildlife Service (USFWS) Report Wind Energy, Land-Based Wind Collision Bats, Human Dimensions, Environmental Impact Assessment
Final 2012-2013 Annual Report Avian and Bat Monitoring Project Vasco Winds, LLC Brown, K., Smallwood, K., Karas, B. Report Wind Energy, Land-Based Wind Collision Bats, Birds
Long-Term Trends in Fatality Rates of Birds and Bats in the Altamont Pass Wind Resource Area, California Smallwood, S. Report Wind Energy, Land-Based Wind Collision Bats, Birds
Estimating Bat and Bird Mortality Occurring at Wind Energy Turbines from Covariates and Carcass Searches Using Mixture Models Korner-Nievergelt, F., Brinkmann, R., Niermann, I., Behr, O. Journal Article Wind Energy, Land-Based Wind Collision Birds, Bats
Regional-Scale Modelling of the Cumulative Impact of Wind Farms on Bats Roscioni, F., Russo, D., Di Feggraro, M., Frate, L., Carranza, M., Loy, A. Journal Article Wind Energy, Land-Based Wind Habitat Change, Collision Bats
Estimation of Bird and Bat Mortality at Wind-Power Farms with Superpopulation Models Peron, G., Hines, J., Nichols, J., Kendall, W., Peters, K., Mizrahi, D. Journal Article Wind Energy, Land-Based Wind Collision Birds, Bats
Survey of Bat Mortalities at a Wind-Energy Facility in North Dakota Bicknell, L., Gilliam, E. Journal Article Wind Energy, Land-Based Wind Collision Bats
Thresholds for Bats Killed by Wind Turbines Arnett, E., Barclay, R., Hein, C. Journal Article Wind Energy, Land-Based Wind Collision Bats
Report of the IWG on Wind Turbines and Bat Populations 2013 Rodrigues, L. Report Wind Energy, Land-Based Wind Collision, Habitat Change Bats
Bat Fatality at a Wind Energy Facility in the Western Cape, South Africa Aronson, J., Thomas, A., Jordaan, S. Journal Article Wind Energy, Land-Based Wind Attraction, Collision Bats
Effectiveness of an Operational Mitigation Experiment to Reduce Bat Fatalities at the Pinnacle Wind Farm, Mineral County, West Virginia, 2012 Hein, C., Prichard, A., Mabee, T., Schirmacher, M. Report Wind Energy, Land-Based Wind Attraction, Avoidance, Collision Bats
Effectiveness of Search Dogs Compared with Human Observers in Locating Bat Carcasses at Wind-Turbine Sites: A Blinded Randomized Trial Mathews, F., Swindells, M., Goodhead, R., August, T., Hardman, P., Linton, D., Hosken, D. Journal Article Wind Energy, Land-Based Wind Collision Bats
Avian and Bat Assessment at the Lewes Wind Turbine University of Delaware College of Earth, Ocean and Environment Buler, J., Horton, K., Shriver, G. Report Wind Energy, Land-Based Wind Collision Bats, Birds
Hatchet Ridge Wind Farm Post-Construction Mortality Monitoring Year Two Annual Report Tetra Tech Inc. Report Wind Energy, Land-Based Wind Collision Bats, Birds
A Synthesis of Operational Mitigation Studies to Reduce Bat Fatalities at Wind Energy Facilities in North America Arnett, E., Johnson, G., Erickson, W., Hein, C. Report Wind Energy, Land-Based Wind Collision Bats
Calculation of Wind Farm Production Losses via MERRA Data in Consequence of Bat Based Temporary Wind Turbine Shut Downs Raabe, J., Schorer, T., Junge, J. Journal Article Wind Energy, Land-Based Wind Collision Bats
Chirotech, Six years of research (2006 – 2012) Rico, P., Lagrange, H., Ughetto, A., Melki, F., Kerbiriou, C. Presentation Wind Energy, Land-Based Wind Collision Bats
Improving Methods for Estimating Fatality of Birds and Bats at Wind Energy Facilities Warren-Hicks, W., Newman, J., Wolpert, R., Karas, B., Tran, L. Report Wind Energy, Land-Based Wind Attraction, Avoidance, Collision, Displacement Bats, Birds
Bat Evaluation Monitoring Studies at the Fowler Ridge Wind Farm Benton County, Indiana Good, R., Sonnenberg, M., Simon, S. Report Wind Energy, Land-Based Wind Collision Bats
2012 Post-Construction Monitoring Study Criterion Wind Project Garrett County, Maryland Young, D., Nations, C., Lout, M., Bay, K. Report Wind Energy, Land-Based Wind Collision, Avoidance Birds, Bats
Bats Killed in Large Numbers at United States Wind Energy Facilities Hayes, M. Journal Article Wind Energy, Land-Based Wind Collision Bats
Proceedings of the Wind-Wildlife Research Meeting IX PNWWRM IX Conference Paper Wind Energy, Land-Based Wind, Fixed Offshore Wind Collision, Habitat Change Bats, Birds
Using Species Distribution Modelling to Predict Bat Fatality Risk at Wind Farms Santos, H., Rodrigues, L., Jones, G., Rebelo, H. Journal Article Wind Energy, Land-Based Wind Habitat Change, Collision Bats
Noctule Bats and Wind Turbines Burrows, L. Journal Article Wind Energy, Land-Based Wind Collision Bats
The avian and wildlife costs of fossil fuels and nuclear power Sovacool, B. Journal Article Wind Energy, Land-Based Wind Displacement, Collision Birds, Bats
Assessment of bat and avian mortality at a pilot wind turbine at Coega, Port Elizabeth, Eastern Cape, South Africa Doty, A., Martin, A. Journal Article Wind Energy, Land-Based Wind Collision Bats, Birds
Factors Influencing Bat Activity and Mortality at a Wind Farm in the Mediterranean Region Amorim, F., Rebelo, H., Rodrigues, L. Journal Article Wind Energy, Land-Based Wind Collision Bats
Regional Analysis of Wind Turbine-caused Bat and Bird Fatality: Final Report Drake, D., Schumacher, S., Sponsler, M. Report Wind Energy, Land-Based Wind Collision Birds, Bats
Bird and Bat Collision Risks & Wind Energy Facilities Willmott, J., Allison Costello, E., Gordon, C., Forcey, G., Casto, S., Beaulac, G., Pilla, E. Report Wind Energy, Land-Based Wind, Fixed Offshore Wind Attraction, Avoidance, Collision, Displacement Bats, Birds
Bat Fatalities at Wind Farms in North-Eastern Greece Georgiakakis, P., Kret, E., Carcamo, B., Doutau, D., Kafkaletou-Diez, A., Vasilakis, D., Papadatou, E. Journal Article Wind Energy, Land-Based Wind Collision, Attraction Bats
Bat fatalities at two wind farms in Tasmania, Australia: bat characteristics, and spatial and temporal patterns Hull, C., Cawthen, L. Journal Article Wind Energy, Land-Based Wind Attraction, Collision, Habitat Change Bats
Bat Mortalities at a Wind Energy Facility in North Dakota Bicknell, L., Gilliam, E. Journal Article Wind Energy, Land-Based Wind Attraction, Avoidance, Collision Bats
Bat Mortality at a Wind Power Facility in Central Canada Jameson, J., Willis, C. Journal Article Wind Energy, Land-Based Wind Collision Bats
Wind development and wildlife mitigation in Wyoming: a primer Jakle, A. Report Wind Energy, Land-Based Wind Avoidance, Collision Bats, Birds, Ground-Nesting Birds, Passerines, Human Dimensions, Environmental Impact Assessment
Evidence of Late-Summer Mating Readiness and Early Sexual Maturation in Migratory Tree-Roosting Bats Found Dead at Wind Turbines Cryan, P., Jameson, J., Baerwald, E., Willis, C., Barclay, R., Snider, E., Crichton, E. Journal Article Wind Energy, Land-Based Wind Collision Bats
Guidelines for Reducing Impacts to Wildlife from Wind Energy Development in Arizona Arizona Game and Fish Department Report Wind Energy, Land-Based Wind Attraction, Avoidance, Collision, Displacement, Habitat Change Bats, Birds
Bat Mortality at a Wind-Energy Facility in Southeastern Wisconsin Grodsky, S., Jennelle, C., Drake, D., Virzi, T. Journal Article Wind Energy, Land-Based Wind Collision Bats
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