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
Proceedings of the NWCC Wildlife Workgroup Research Planning Meeting VI Schwartz, S. Conference Paper Wind Energy, Land-Based Wind, Fixed Offshore Wind Collision, Habitat Change Bats, Birds
A Preliminary Evaluation on the Use of Dogs to Recover Bat Fatalities at Wind Energy Facilities Arnett, E. Journal Article Wind Energy, Land-Based Wind Collision Bats
Preliminary Field Test Results of an Acoustic Deterrent with the Potential to Reduce Bat Mortality from Wind Turbines Szewczak, J., Arnett, E. Report Wind Energy, Land-Based Wind Collision Bats
Patterns of Pre-Construction Bat Activity at a Proposed Wind Facility in South-Central Pennsylvania Arnett, E., Hayes, J., Huso, M. Report Wind Energy, Land-Based Wind Collision, Habitat Change Bats
Patterns of Pre-Construction Bat Activity Determined Using Acoustic Monitoring at a Proposed Wind Facility in South-Central Wisconsin Redell, D., Arnett, E., Hayes, J., Huso, M. Report Wind Energy, Land-Based Wind Collision, Habitat Change Bats
Battered by harsh winds - must bats pay the price for wind energy? Tuttle, M. Magazine Article Wind Energy, Land-Based Wind Collision, Attraction Bats
Impacts on Wildlife and Government Responsibilities for Regulating Development and Protecting Wildlife Office, United States Government Accountability Report Wind Energy, Land-Based Wind Habitat Change, Displacement, Collision, Avoidance Legal & Policy, Human Dimensions, Birds, Bats
Relationships between Bats and Wind Turbines in Pennsylvania and West Virginia: An Assessment of Fatality Search Protocols, Patterns of Fatality, and Behavioral Interactions with Wind Turbines Arnett, E., Erickson, W., Kerns, J., Horn, J. Report Wind Energy, Land-Based Wind Collision Bats
Proceedings of the Onshore Wildlife Interactions with Wind Developments: Research Meeting V Schwartz, S. Conference Paper Wind Energy, Land-Based Wind Collision, Habitat Change Bats, Birds
Bat Activity, Composition, and Collision Mortality At a Large Wind Plant in Minnesota Johnson, G., Perlik, M., Erickson, W., Strickland, M. Journal Article Wind Energy, Land-Based Wind Attraction, Avoidance, Collision Bats
Assessment of Bat Mortality and Activity at Buffalo Mountain Windfarm, Eastern Tennessee Fiedler, J. Thesis Wind Energy, Land-Based Wind Collision Bats
A Preliminary Assessment of Potential Avian Interactions at Four Proposed Wind Energy Facilities on Vandenberg Air Force Base, California: Period of Performance: November 2001 - May 2002 BioResource Consultants Report Wind Energy, Land-Based Wind Collision Bats, Birds
When Blade Meets Bat Williams, W. Magazine Article Wind Energy, Land-Based Wind Collision Bats
Bat Deaths and Wind Turbines - A Review of Current Knowledge, and of the Information Available in the Database for Germany Durr, T., Bach, L. Journal Article Wind Energy, Land-Based Wind Attraction, Collision Bats
Wind Turbines and Bats - A Pilot Study Ahlén, I. Report Wind Energy, Land-Based Wind Collision, Attraction Passerines, Birds, Bats
Bat Interactions With Wind Turbines at the Buffalo Ridge, Minnesota Wind Resource Area: An Assessment of Bat Activity, Species Composition, and Collision Mortality Johnson, G., Perlik, M., Erickson, W., Strickland, M., Shepherd, D., Sutherland, P. Report Wind Energy, Land-Based Wind Collision, Avoidance, Attraction Bats
Nine Canyon Wind Power Project Avian and Bat Monitoring Report Erickson, W., Kronner, K., Gritski, B. Report Wind Energy, Land-Based Wind Collision Bats, Birds
Avian and Bat Mortality Associated with the Initial Phase of the Foote Creek Rim Windpower Project, Carbon County, Wyoming November 1998-June 2002 Young, D. Jr., Erickson, W., Good, R., Strickland, M., Johnson, G. Report Wind Energy, Land-Based Wind Collision Bats, Birds, Passerines, Raptors, Shorebirds, Waterfowl
National Wind Technology Center Site Environmental Assessment: Bird and Bat Use and Fatalities - Final Report Schmidt, E., Piaggo, A., Bock, C., Armstrong, D. Report Wind Energy, Land-Based Wind Habitat Change, Collision Birds, Bats
Mortality of Bats at a Large-Scale Wind Power Development at Buffalo Ridge, Minnesota Johnson, G., Erickson, W., Strickland, M., Shepherd, M., Shepherd, D., Sarappo, S. Journal Article Wind Energy, Land-Based Wind Collision Bats
A Roadmap for PIER Research on Avian Collisions with Wind Turbines in California Sterner, D. Report Wind Energy, Land-Based Wind Collision Bats, Birds, Raptors
Assessment of Bat Community Structure and Roosting Habitat Preferences for the Hoary Bat (Lasiurus cinereus) Near Foote Creek Rim, Wyoming Gruver, J. Thesis Wind Energy, Land-Based Wind Collision Bats
Synthesis and Comparison of Baseline Avian and Bat Use, Raptor Nesting and Mortality Information from Proposed and Existing Wind Developments Erickson, W., Johnson, G., Young, D., Strickland, D., Good, R., Bourassa, M., Bay, K., Sernka, K. Report Wind Energy, Land-Based Wind Habitat Change, Collision Birds, Bats
Avian/Wind Turbine Interactions: A Short Summary of Research Results and Remaining Questions National Wind Coordinating Collaborative Report Wind Energy, Land-Based Wind Collision, Habitat Change Bats, Birds
Status of Avian Research at the National Renewable Energy Laboratory Sinclair, K. Conference Paper Wind Energy, Land-Based Wind Collision, Habitat Change Bats, Birds
Proceedings of the National Avian - Wind Power Planning Meeting IV NWCC Avian Subcommittee Conference Paper Wind Energy, Land-Based Wind Collision, Habitat Change Bats, Birds, Raptors
Monitoring of Seasonal Bird Activity and Mortality on Unit 2 at the Buffalo Ridge Windplant, Minnesota Higgins, K., Dieter, C., Usgaard, R. Report Wind Energy, Land-Based Wind Habitat Change, Collision Birds, Bats
Wind Power and the Local Environment - No Free Lunches Plowden, B. Conference Paper Wind Energy, Land-Based Wind Collision, Habitat Change Bats, Birds
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