In this animated graphic of bats' calls in flight, two bats are represented by different colors, red and blue. The bats' movements and vocalizations have been slowed by a factor of 10. The top graph in the movie traces the bats' movements around a flight room where the study took place. Each circle on the bats' paths indicates a vocalization. The frequency-modulated bout vocalizations are in green. The prey is a tethered mealworm in the center of the room, represented by a yellow circle.
The bottom bars show characteristics of the bats' calls -- from top to bottom: pulse interval (the amount of time between calls), duration, and frequency. Again, the frequency-modulated bout calls are in green.