Bats synchronize changes in sonar vocalizations with head waggles and ear wiggles to help them locate their prey, as shown in this video.
When Melville Wohlgemuth noticed the big brown bats he works with cocked their heads to the side, just like his pet Pug, he decided to investigate why. His recent study describes how echolocating bats use active sensing to perceive the world in high resolution, and tightly co-ordinate their outgoing sonar vocalizations with ear and head movements to sharpen their senses when detecting and localizing prey.
Wohlgemuth and colleagues trained echolocating bats to track moving insects from a stationary position and analyzed the coordinated changes in outgoing sonar vocalizations with the 3D positions of the head and ears during sonar echo reception.
In the three-part video, the bat is shown tracking a moving insect. The first segment shows the bat tracking a mealworm from three meters away, while the second segment shows a zoomed in version. In both, the sounds that are heard are produced by a bat detector to make bat vocalizations audible to the human ear. The final segment was captured with high-speed video recording, and has been slowed down by a factor of 10, which also makes the bat’s vocalizations audible. Displayed on the bottom is the ongoing spectrographic representation of the bat’s vocalizations.
Co-author Cynthia Moss notes that other animals are also known to use active sensing – for example, the ear twitches of an alert cat. Studying these phenomena can provide insight into how movement helps animals sense their environment.
Research Article: Wohlgemuth MJ, Kothari NB, Moss CF (2016) Action Enhances Acoustic Cues for 3-D Target Localization by Echolocating Bats. PLoS Biol 14(9): e1002544. doi:10.1371/journal.pbio.1002544
Additional Videos available at: http://plos.io/2c0hfPb
Image and Video Credit: Melville J. Wohlgemuth. (2016)