RESULTS OF TESTING AN ULTRASONIC BAT DETERRENT FOR FURTHER APPLICATION AT WIND POWER PLANTS

Abstract

The article presents the results of a two-stage bioacoustic testing of the domestically manufactured ultrasonic deterrent «SuperCat-1000», aimed at assessing its effectiveness in minimizing the risk of bat collisions with wind turbines (WTs). The relevance of this study is driven by the need to identify effective technical solutions to reduce bat mortality at wind power plants (WPPs), while minimizing the economic losses associated with complete turbine shutdowns. Experimental research was conducted during 2023–2024 using the Echo Meter Touch 2 Pro bioacoustic detector and spectral analysis software. The methodology involved alternating periods with the “SuperCat-1000” switched on and off to ensure statistically reliable comparisons of animal activity. The initial field trials (2023) showed that the device signals in the 34–37 kHz and 44–48 kHz ranges did not overlap with the main echolocation frequencies of the Pipistrellus pygmaeus, 56–72 kHz. This confirmed the absence of any noticeable effect on the behavior of this species and demonstrated the ineffectiveness of non-adapted deterrent devices. During the second stage (2024), following technical modifications by the manufacturer, the deterrent was retuned to the 23–30 kHz range, which corresponds to the echolocation frequencies of a vulnerable species – the Common Noctule (Nyctalus noctula). As a result, a decrease in the acoustic activity of this species was recorded: the number of bat passes within the active zone of the operating deterrent decreased to 7, compared to 12 passes during control periods when the device was turned off, over equal time intervals. An important outcome of the study was the identification of the physical limitations of the method: the effective propagation distance of the ultrasonic signal was determined to be 15–20 meters, beyond which wave intensity decreases critically. This indicates that ultrasonic deterrents can be effective only as localized protection tools (e.g., for nacelle-level mitigation), but they cannot cover the full rotor-swept area of modern wind turbines. The findings confirm the potential of ultrasonic deterrents as auxiliary technical mitigation tools. The authors demonstrated that the device’s effectiveness is strongly species-specific and depends on the precise alignment of the emitted frequencies with the peak echolocation frequencies of target species. The implementation of multi-frequency signal generation modes and the development of adaptive operational algorithms based on preliminary site-specific fauna monitoring are proposed. It is recommended to combine ultrasonic systems with curtailment strategies (turbine shutdown during peak risk periods) to ensure maximum biodiversity protection. The article presents the results of a two-stage bioacoustic testing of an ultrasonic deterrent device of the «SuperCat-1000» type, aimed at assessing its effectiveness for minimizing the risk of bat collisions with wind energy installations. The primary tests showed that the signal of the device within the range of 34–37, 44–48 kHz does not overlap the main echolocation frequencies of the pygmy pipistrelle Pipistrellus pygmaeus (56–72 kHz), which confirms the absence of a noticeable influence on the behaviour of this species. After modification (adjustment of the range to 23–30 kHz), the device was adapted to the frequencies of the Nyctalus noctula. As a result, a decrease in its activity was recorded: the number of registrations within the action zone of the deterrent decreased from twelve (during periods when the device was turned off) to seven (during periods when the device was turned on) for equal time intervals. The obtained results confirm the potential effectiveness of ultrasonic deterrent devices as a local technical means for minimizing the influence of wind energy installations on bats. It is noted that the effectiveness of the device has a species-specific character and depends on the frequency adjustment, signal intensity, environmental conditions, and spatial activity of the animals. The introduction of a multi-frequency mode adapted to the echolocation ranges of specific bat species occurring in the area of wind energy installations, as well as further testing of the device under various altitudes and weather conditions, is proposed. The combination of ultrasonic systems with operational restrictions of wind turbines and preliminary monitoring of the local fauna is recommended.