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
Baseline investigations of bats and birds at wind turbine test Centre Asterild Therkildsen, O., Elmeros, M., Kahlert, J., Desholm, M. Report Wind Energy, Land-Based Wind Displacement, Collision, Avoidance, Attraction Birds, Bats
The Catchment Area of Wind Farms for European Bats: A Plea for International Regulations Voigt, C., Popa-Lisseanu, A., Niermann, I., Kamer-Schadt, S. Journal Article Wind Energy, Land-Based Wind Collision Bats
A Habitat-Based Wind-Wildlife Collision Model with Application to the Upper Great Plains Region Forcey, G. Report Wind Energy, Land-Based Wind Collision, Avoidance, Attraction Birds, Bats
Scavenger removal: Bird and bat carcass persistence in a tropical wind farm Villegas-Patraca, R., Macias-Sanchez, S., Macgregor-Fors, I., Munoz-Robles, C. Journal Article Wind Energy, Land-Based Wind Collision Birds, Bats
Fixing wind power's bat problem Kumagai, J. Journal Article Wind Energy, Land-Based Wind Collision Bats
Bat Fatalities at Wind Farms in Northern Spain - Lessons to be Learned Camina, A. Journal Article Wind Energy, Land-Based Wind Collision Bats
Report of the IWG on Wind Turbines and Bat Populations 2012 Rodrigues, L. Conference Paper Wind Energy, Land-Based Wind Collision, Habitat Change Bats
The BIO-acoustic feature extraction and classification of bat echolocation calls Mirzaei, G., Majid, M., Ross, J., Jamali, M., Gorsevski, P., Frizado, J., Bingman, V. Conference Paper Wind Energy, Land-Based Wind Collision Bats
2011 Post-Construction Monitoring Study Criterion Wind Project Garrett County, Maryland Young, D., Lout, M., Courage, Z., Nomani, S., Bay, K. Report Wind Energy, Land-Based Wind Collision Birds, Bats
Criterion Wind Project Avian Protection Plan Young, D., Tidhar, D. Report Wind Energy, Land-Based Wind Displacement, Collision, Avoidance, Attraction Legal & Policy, Human Dimensions, Birds, Bats
U.S. Fish and Wildlife Service Land-Based Wind Energy Guidelines US Fish and Wildlife Service (USFWS) Guidance Wind Energy, Land-Based Wind Collision, Displacement, Habitat Change Bats, Birds, Terrestrial Mammals, Human Dimensions
Best Management Practices for siting, developing, operating, and monitoring renewable energy in the Intermountain West: A Conservationist's Guide Jones, A. Report Wind Energy, Land-Based Wind Habitat Change, Displacement, Collision, Avoidance, Attraction Terrestrial Mammals, Raptors, Legal & Policy, Human Dimensions, Ground-Nesting Birds, Birds, Bats
Putting Aeolus to work without the death toll: federal wind farm siting guidelines can mitigate avian and Chiropteran mortality Mensing, B. Journal Article Wind Energy, Land-Based Wind Collision, Habitat Change Bats, Birds, Raptors
Draft Black Oak & Getty Wind Avian and Bat Protection Plan Black Oak Wind, Getty Wind Company Report Wind Energy, Land-Based Wind Attraction, Collision, Displacement, Habitat Change Bats, Birds
Avian and Bat Protection Plan for the Ocotillo Wind Energy Facility Ocotillo Express Report Wind Energy, Land-Based Wind Attraction, Avoidance, Collision, Displacement, Habitat Change Bats, Birds, Raptors
A Forensic Investigation Into the Etiology of Bat Mortality at a Wind Farm: Barotrauma or Traumatic Injury? Rollins, K., Meyerholz, D., Johnson, G., Capparella, A., Loew, S. Journal Article Wind Energy, Land-Based Wind Collision Bats
Big Blue Wind Energy Project Avian and Bat Protection Plan Western Ecosystems Technology Inc (WEST) Report Wind Energy, Land-Based Wind Avoidance, Collision, Displacement, Habitat Change Bats
Effects of Acoustic Deterrents on Foraging Bats Johnson, J., Ford, W., Rodrigue, J., Edwards, J. Report Wind Energy, Land-Based Wind Collision Bats
Have we all gone batty? The need for a better balance between the conservation of protected species and the development of clean renewable energy Householder, L. Journal Article Wind Energy, Land-Based Wind Collision, Habitat Change Bats, Human Dimensions
Avian and Bat Protection Plan: AWA Goodhue Wind Project Westwood Professional Services Report Wind Energy, Land-Based Wind Attraction, Avoidance, Collision, Displacement, Habitat Change Bats, Birds
A new method to determine bird and bat fatality at wind energy turbines from carcass searches Korner-Nievergelt, F., Korner-Nievergelt, P., Behr, O., Niermann, I., Hellriegel, B. Journal Article Wind Energy, Land-Based Wind Habitat Change, Collision Birds, Bats
Evaluating the Effectiveness of an Ultrasonic Acoustic Deterrent in Reducing Bat Fatalities at Wind Energy Facilities - Final Report Arnett, E., Hein, C., Schirmacher, M., Baker, M., Huso, M., Szewczak, J. Report Wind Energy, Land-Based Wind Avoidance, Collision Bats
Enhancing Carcass Removal Trials at Three Wind Energy Facilities in Portugal Bernardino, J., Bispo, R., Torres, P., Rebelo, R., Mascarenhas, M., Costa, H. Journal Article Wind Energy, Land-Based Wind Collision Birds, Bats
Using echolocation monitoring to model bat occupancy and inform mitigations at wind energy facilities Weller, T., Baldwin, J. Journal Article Wind Energy, Land-Based Wind Habitat Change, Collision Bats
Bat Fatality Monitoring Report for the Pigeon Creek Wind Turbine Dewitt, S. Report Wind Energy, Land-Based Wind Collision Bats
Investigating the Causes of Death for Wind Turbine-Associated Bat Fatalities Grodsky, S., Behr, M., Gendler, A., Drake, D., Dieterle, B., Rudd, R., Walrath, N. Journal Article Wind Energy, Land-Based Wind Collision Bats
Assessing Bird and Bat Mortality at the Forward Energy Center Grodsky, S., Drake, D. Report Wind Energy, Land-Based Wind Collision Bats, Birds
Using Stakeholder Input to Develop a Comparative Risk Assessment for Wildlife from the Life Cycles of Six Electrical Generation Fuels Zillioux, E., Newman, J., Lampman, G., Watson, M., Newman, C. Book Chapter Wind Energy, Land-Based Wind Habitat Change, Collision Stakeholder Engagement, Life Cycle Assessment, Human Dimensions, Birds, Bats
Patterns of activity and fatality of migratory bats at a wind energy facility in Alberta, Canada Baerwald, E., Barclay, R. Journal Article Wind Energy, Land-Based Wind Habitat Change, Collision Bats
Wind turbines as landscape impediments to the migratory connectivity of bats Cryan, P. Journal Article Wind Energy, Land-Based Wind Attraction, Collision Bats
Avian, Bat and Habitat Cumulative Impacts Associated with Wind Energy Development in the Columbia Plateau Ecoregion Of Eastern Washington and Oregon 2011 Johnson, G., Erickson, W. Report Wind Energy, Land-Based Wind Avoidance, Collision, Displacement, Habitat Change Bats, Birds, Raptors
Klondike IIIa (Phase 2) Wind Power Project Wildlife Monitoring Year One Summary August 2008–August 2010 Gritski, B., Downes, S., Kronner, K. Report Wind Energy, Land-Based Wind Collision Bats, Birds
An Assessment of the Bat Fauna at the Hepburn Community Wind Farm, Leonards Hill, Victoria Richards, G. Report Wind Energy, Land-Based Wind Attraction, Collision Bats
Post-Construction Bird and Bat Mortality Study: Cedar Ridge Wind Farm, Fond Du Lac County, Wisconsin BHE Environmental Inc Report Wind Energy, Land-Based Wind Collision Bats, Birds
Year 1 Post-construction Avian and Bat Monitoring Report: Biglow Canyon Wind Farm Phase II Sherman County, Oregon Enk, T., Bay, K., Sonnenberg, M., Flaig, J., Boehrs, J., Palochak, A. Report Wind Energy, Land-Based Wind Collision Bats, Birds
Bat Mortality and Activity at a Northern Iowa Wind Resource Area Jain, A., Koford, R., Hancock, A., Zenner, G. Journal Article Wind Energy, Land-Based Wind Collision, Avoidance, Attraction Bats
Post construction monitoring of wind farms: First records of direct impact on bats in Italy Ferri, V., Locasciulli, O., Soccini, C., Forlizzi, E. Journal Article Wind Energy, Land-Based Wind Collision Bats
Patterns of Bird and Bat Fatality at the Locust Ridge II Wind Farm, Pennsylvania Arnett, E., Schirmacher, M., Hein, C., Bat Conservation International, Huso, M. Report Wind Energy, Land-Based Wind Collision Bats, Birds
Mortality of Bats at Wind Turbines Links to Nocturnal Insect Migration? Rydell, J., Bach, L., Dubourg-Savage, M., Green, M., Rodrigues, L., Hedenstrom, A. Journal Article Wind Energy, Land-Based Wind Collision Bats
Temporal Patterns in Capture Rate and Sex Ratio of Forest Bats in Arkansas Perry, R., Carter, S., Thill, R. Journal Article Wind Energy, Land-Based Wind Collision Bats
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