A method of flight path and chirp pattern reconstruction for multiple flying bats

Many species of bats use frequency-modulated (FM) “chirps” to sense their environment by sonar. A method was developed for locating the chirps of individual bats while simultaneously tracking the positions of multiple bats in infrared videos. Three microphones and one infrared camera recorded multiple bats flying above a small open pool. Azimuth and elevation was computed for all chirps in a given 15-s interval and matched to position coordinates given by the infrared camera. By grouping spatially continuous sets of chirps, each individual bat's chirp pattern can be obtained. This combination of visual and acousticinformation will provide new insight into the behavior and sonar capabilities of FM ranging bats.