Bats in the changing climate: how weather impacts echolocation
Bats in the changing climate: how weather impacts echolocation lead image
Fuzzy, with a scrunched face, oversized ears, and the ability to fit comfortably in your palm, the common pipistrelle bat can be found across the Eastern Hemisphere. Like other bats, they use echolocation to navigate and locate insect prey.
However, echolocation is weather-dependent and certain conditions could decrease bat detection distance. De Framond et al. studied the impact of varying weather on echolocation for the common pipistrelle and other species. They also investigated if the bats adjusted their echolocation calls to accommodate the weather.
“Echolocation relies on the perceptions of echoes reflected off surrounding objects after the emission of an ultrasonic call,” said author Léna de Framond. “These echoes are faint partly because air absorbs the sound. This absorption is extreme at ultrasonic frequencies and varies by temperature, humidity, and air pressure.”
The detection distance is impacted by complex factors like weather, desired insect size, as well as call energy and frequency.
The researchers arranged a star-shaped microphone array and weather station together. Using the time delay between signals on the microphones, they triangulated bats’ paths and reconstructed the bats’ emitted echolocation calls from the recordings.
“We installed our setup at dusk near lakes and rivers because these are insect-rich places,” said de Framond. “It was nice to sit and watch the small shadows flying around, sometimes three or four at once, and they go fast!”
The bats’ echolocation detection distance fluctuated by 20% in a season due to weather, but the precise impacts of increased temperature and humidity are difficult to predict. Though some bats altered their calls with the weather, the change did not increase the detection distance.
Source: “Temperate bats may alter calls to partially compensate for weather-induced changes in detection distance,” by Léna de Framond, Verena Reininger, and Holger R. Goerlitz, Journal of the Acoustical Society of America (2023). The article can be accessed at https://doi.org/10.1121/10.0019359 .
