Neuroecologist Yossi Yovel and his colleagues at Tel Aviv University have developed the first bat-wearable microphone to study the echolocation chirps of greater mouse-tailed bats in Israel’s Hula Valley. These bats are able to fly in crowded conditions without colliding with each other, and the researchers wanted to understand how they manage to do so. They found that the bats’ echolocation signals often partially mask each other, similar to the communication difficulties faced by humans in a crowded cocktail party. However, the bats have surprisingly few collisions despite these challenges.
Initially, the researchers could only record the bats from the ground, limiting the information they could gather. To overcome this, they designed and attached small microphones to the bats, weighing only four grams. By using these microphones along with flight path data from tracked bats, they were able to create computer models of bat behavior and echolocation. This allowed them to study how the bats use echolocation to locate obstacles, prey, and each other in flight.
At the narrow exit hole of the cave where the bats emerge, up to 90 percent of the echolocation signals can be masked. However, signals from nearby bats are less likely to be masked, especially those from bats directly in front who are projecting calls forward. The researchers also found that the bats tend to start moving to the side as soon as they emerge from the cave, reducing the risk of collisions. By flying with enough distance between each other, the bats are able to hear their own echolocation signals and avoid collisions.
This study on bat echolocation could be compared to the challenge faced by fringe-lipped bats hunting túngara frogs in Central and South America. These bats rely on echolocation to target individual calling frogs amongst the cacophony of sounds in a frog-pool. By pinging the frogs’ throat pouches, the bats are able to locate and catch their prey efficiently. The development of bat-wearable microphones has allowed researchers to gain insights into the echolocation behavior of bats and how they avoid collisions while flying in close proximity to each other.
The research published in the Proceedings of the National Academy of Sciences showcases the innovative approach taken by Yovel and his team to study bat behavior and echolocation. By attaching small microphones to bats weighing less than a nickel, they were able to record in-air echolocation signals and study how the bats navigate crowded flight conditions. This technology has provided new insights into how bats use echolocation to communicate and avoid collisions, shedding light on their impressive ability to fly in crowded conditions without incidents.
Overall, the study highlights the importance of studying animal behavior and communication in challenging conditions such as crowded flight. By understanding how bats use echolocation to navigate and communicate in flight, researchers can gain valuable insights into the sensory capabilities of these animals. The development of the first bat-wearable microphone opens up new possibilities for studying bat behavior and communication in various contexts, providing a deeper understanding of these fascinating flying mammals.
