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
Impact of wind facilities on bats in the Neotropics Rodríguez-Durán, A., Feliciano-Robles, W. Journal Article Wind Energy, Land-Based Wind Collision, Attraction Bats
Synopsis des internationalen Kenntnisstandes zum Einfluss der Windenergie auf Fledermäuse und Vögel und Spezifizierung für die Schweiz Muller, J., Warnke, M., Reichenbach, M., Köppel, J. Report Wind Energy, Land-Based Wind Collision Birds, Bats
Post-Construction Avian and Bat Fatality at the Horse Butte Wind Facility, Years 1–3 SWCA Environmental Consultants Report Wind Energy, Land-Based Wind Collision Bats, Birds
Impacts of Wind Energy on Environment: A Review Wang, S., Wang, S. Journal Article Wind Energy, Land-Based Wind Attraction, Collision Bats, Birds
Post-Construction Avian and Bat Mortality Monitoring at the Alta Wind Energy Center, Phase X, Kern County, California. Final Report for the First Year of Operation: March 2014 – March 2015 Chatfield, A., Levenstein, K., DiDonato, G. Report Wind Energy, Land-Based Wind Collision Bats, Birds
Do Habitat Characteristics Determine Mortality Risk for Bats at Wind Farms? Modelling Susceptible Species Activity Patterns and Anticipating Possible Mortality Events Ferreira, D., Freixo, C., Cabral, J., Santos, R., Santos, M. Journal Article Wind Energy, Land-Based Wind Collision Bats
Estimating Wind-Turbine Caused Bird and Bat Fatality when Zero Carcasses are Observed Huso, M., Dalthorp, D., Dail, D., Madsen, L. Journal Article Wind Energy, Land-Based Wind Collision Bats, Birds
Regional Analysis of Wind Turbine-Caused Bat Mortality Drake, D., Jennelle, C., Liu, J., Grodsky, S., Schumacher, S., Sponsler, M. Journal Article Wind Energy, Land-Based Wind Collision Bats
Wildlife and Renewable Energy: German Politics Cross Migratory Bats Voigt, C., Lehnert, L., Petersons, G., Adorf, F., Bach, L. Journal Article Wind Energy, Land-Based Wind Collision Bats
Design and Testing of an Integrated Wildlife-Wind Turbine Interactions Detection System Flowers, J. Thesis Wind Energy, Land-Based Wind Collision Bats, Birds
Estimates and Correlates of Bird and Bat Mortality at Small Wind Turbine Sites Minderman, J., Fuentes-Montemayor, E., Pearce-Higgins, J., Pendlebury, C., Park, K. Journal Article Wind Energy, Land-Based Wind Collision Bats, Birds
How to Mitigate Impacts of Wind Farms on Bats? A Review of Potential Conservation Measures in the European Context Peste, F., Paula, A., Pinto da Silva, P., Bernardino, J., Pereira, P., Mascarenhas, M., Costa, H., Vieira, J., Bastos, C., Fonseca, C., Pereira, M. Journal Article Wind Energy, Land-Based Wind Displacement, Collision, Avoidance, Attraction Bats
Observations from the Use of Dogs to Undertake Carcass Searches at Wind Facilities in Australia Bennett, E. Book Chapter Wind Energy, Land-Based Wind Collision Bats, Birds
Fauna Collisions with Wind Turbines: Effects and Impacts, Individuals and Populations. What Are We Trying to Assess? Smales, I. Book Chapter Wind Energy, Land-Based Wind Collision Bats, Birds
Species composition and mortality of bats at the Osorio Wind Farm, southern Brazil Barros, M., de Magalhaes, R., Rui, A. Journal Article Wind Energy, Land-Based Wind Collision Bats
First Report on Bat Mortalities on Wind Farms in Chile Escobar, L., Juarez, C., Medina-Vogel, G., Gonzalez, C. Journal Article Wind Energy, Land-Based Wind Collision Bats
Review and guidance on use of “shutdown-on-demand” for wind turbines to conserve migrating soaring birds in the Rift Valley/Red Sea Flyway BirdLife International Guidance Wind Energy, Land-Based Wind, Fixed Offshore Wind Collision Bats, Birds
First Year Post-Construction Monitoring of Bats and Birds at Wind Turbine Test Centre Østerild Therkildsen, O., Elmeros, M. Report Wind Energy, Land-Based Wind Collision Birds, Bats
Empirical Evidence for Factors Affecting Searcher Efficiency and Scavenging Rates at a Coastal, Terrestrial Wind-Power Facility Peters, K., Mizrahi, D., Allen, M. Journal Article Wind Energy, Land-Based Wind Collision Birds, Bats
Activity of Tree Bats at Anthropogenic Tall Structures: Implications for Mortality of Bats at Wind Turbines Jameson, J., Willis, C. Journal Article Wind Energy, Land-Based Wind Attraction, Collision Bats
Bird and Bat Conservation Strategy for Invenergy's Pleasant Ridge Wind Project Invenergy Canada Report Wind Energy, Land-Based Wind Collision Bats, Birds
Warning Sounds and Color for Reducing Bird and Bat Mortality at Wind Turbines Khan, S. Conference Paper Wind Energy, Land-Based Wind Collision Bats, Birds
Behavior of Bats at Wind Turbines Cryan, P., Gorresen, P., Hein, C., Schirmacher, M., Diehl, R., Huso, M., Hayman, D., Fricker, P., Bonaccorso, F., Johnson, D., Heist, K., Dalton, D. Journal Article Wind Energy, Land-Based Wind Attraction, Avoidance, Changes in Flow, Collision, Displacement Bats
Wind and Wildlife Fauna Collisions with Wind Turbines: Effects and Impacts, Individuals and Populations. What Are We Trying to Assess? Smales, I. Conference Paper Wind Energy, Land-Based Wind Collision Bats, Birds
Massive Bat Migration Across the Alps: Implications for Wind Energy Development Bontadina, F., Beck, A., Dietrich, A., Dobner, M., Eicher, C., Frey-Ehrenbold, A., Krainer, K., Loecher, F., Maerki, K., Mattei-Roesli, M., Mixanig, H., Plank, M., Vorauer, A., Wegleitner, S., Widerin, K., Wieser, D., Wimmer, B., Reiter, G. Conference Paper Wind Energy, Land-Based Wind Collision Bats
The challenges and possible solutions of horizontal axis wind turbines as a clean energy solution for the future Ahmed, N., Cameron, M. Journal Article Wind Energy, Land-Based Wind, Fixed Offshore Wind Collision, Noise Bats, Birds
Origins and Migratory Patterns of Bats Killed by Wind Turbines in Southern Alberta: Evidence from Stable Isotopes Baerwald, E., Patterson, W., Barclay, R. Journal Article Wind Energy, Land-Based Wind Collision Bats
Wind Farm Facilities in Germany Kill Noctule Bats from Near and Far Lehnert, L., Kramer-Schadt, S., Schonborn, S., Lindecke, O., Niermann, I., Voigt, C. Journal Article Wind Energy, Land-Based Wind Collision Bats
Historical Challenges of Wind Energy/Wildlife Interactions: How This May Affect Distributed Wind Sinclair, K. Report Wind Energy, Land-Based Wind Habitat Change, Collision Birds, Bats
Red Aviation Lights on Wind Turbines do not Increase Bat-Turbine Collisions Hale, A., Bennett, V. Journal Article Wind Energy, Land-Based Wind Lighting, Collision Bats
Assessing Bat and Bird Fatality Risk at Wind Farm Sites using Acoustic Detectors Heist, K. Thesis Wind Energy, Land-Based Wind Collision Bats, Birds
Fuzzy Clustering in Avian Infrared Imagery Application Mirzaei, G., Ross, J., Jamali, M., Gorsevski, P., Bingman, V. Conference Paper Wind Energy, Land-Based Wind Collision Bats, Birds
Applying Research to Conservation: Science-Based Strategies Can Save Bats at Wind Farms Baerwald, E., Barclay, R. Magazine Article Wind Energy, Land-Based Wind Collision Bats
A Comment on "Bats Killed in Large Numbers at United States Wind Energy Facilities" Huso, M., Dalthorp, D. Journal Article Wind Energy, Land-Based Wind Collision Bats
Grande Prairie Wind Farm Bird and Bat Conservation Strategy Stantec Consulting Report Wind Energy, Land-Based Wind Attraction, Collision, Displacement, Habitat Change Bats, Birds
Hatchet Ridge Wind Farm Post-Construction Mortality Monitoring Comprehensive Three Year Report Tetra Tech Inc. Report Wind Energy, Land-Based Wind Collision Bats, Birds
Wolfe Island Wind Plant Post-Construction Follow-up Plan Bird and Bat Resource Stantec Consulting Report Wind Energy, Land-Based Wind Collision Bats, Birds, Ground-Nesting Birds, Raptors
Accounting for Unsearched Areas in Estimating Wind Turbine-Caused Fatality Huso, M., Dalthorp, D. Journal Article Wind Energy, Land-Based Wind Collision Bats, Birds
Evidence that Bats Perceive Wind Turbine Surfaces to be Water McAlexander, A. Thesis Wind Energy, Land-Based Wind Collision, Attraction Bats
Leaning Juniper II Wind Power Facility Wildlife Fatality Monitoring Study January 2011-July 2013 Downes, S. Report Wind Energy, Land-Based Wind Collision Bats, Birds
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