Ultrasonic bat deterrents: what we do & don't know about its functionality and limits
Presentation Description: With the first commercial installation of ultrasonic Bat Deterrent Systems occurring in 2019, it is important to discuss what we do and do not know about this technology at this point in time. This topic is comprised of two subtopics: how ultrasound actually deters bats and how ultrasound propogates through atmosphere. Bats use ultrasound, commonly known as echolocation, to orient themselves and forage in the dark. It has repeatedly been shown that bats avoid areas treated with ultrasound. Yet species specific differences in effectiveness complicate the picture. We know that indivdual bat species use different types of ultrasonic calls (e.g. frequency, shape, duration) in response to the different ecological niches they occupy. Common understanding of the ‘jamming’ mechanism is that the sound volume at the bat’s characteristic frequency is the most important part of the equation, but there is now evidence suggesting that the process is more complicated than that. The second subtopic focuses on the physics of ultrasound. While ultrasound can seem exotic, it is really just acoustic waves (sound) at a higher frequency than what humans can hear and follows all the same physics principles. Demystifying the basics of ultrasound allows for a clearer understanding of both the benefits and limitations of ultrasound to deter bats from around turbines. This leads to better informed decisions about applications where deterrents are or are not appropriate for minimization.