Mouth gape angle has little effect on the transmitted signals of big brown bats (Eptesicus fuscus)

Bats perform high-resolution echolocation by comparing temporal and spectral features of their transmitted pulses to the received echoes. In complex environments with moving prey, dynamically adapting the transmitted pulses can increase the probability of successful target representation and interception. This study further investigates the adaptive vocal-motor strategies of big brown bats (Eptesicus fuscus). During stationary target detection experiments, echolocation sounds were simultaneously recorded with high-speed, infrared video to examine the relationship of mouth position and movement to pulse characteristics among bats. All three bats produced strobe groups, but the proportion and frequency characteristics of the strobe group pulses differed for individual bats. Additionally, mouth gape angle had little effect on the emitted pulse characteristics, which suggests that laryngeal mechanisms drive changes in emitted pulses.