Dynamic adaptations in the echolocation behavior of bats in response to acoustic interference

Abstract

Abstract Animals must extract relevant sensory information out of a multitude of non-informative and sometimes interfering stimuli. For orientation, bats rely on broadcasted calls and they must assign each echo to the corresponding call. When bats orient in acoustically enriched environments, call-echo assignment becomes challenging due to signal interference. Bats often adapt echolocation parameters which potentially improves signal extraction. However, they also adjust echolocation parameters with respect to target distance. To characterize adaptations that are exclusively elicited to minimize signal interference, we tested the effect of acoustic playback on the echolocation behavior of the fruit-eating bat, Carollia perspicillata. Hereby, distance-dependent changes were considered by swinging bats in a pendulum and directly measuring the object distance. Acoustic playback evoked different call adjustments in parameters such as bandwidth, peak-frequency, duration and call level. These adaptations were highly dynamic and could vary across individuals, days, trials, and even within trials. Our results demonstrate that bats do not only change one echolocation parameter when orienting in acoustically enriched environments. They rather have a tool-kit of different behavioral adaptations to cope with interfering acoustic stimuli. By dynamically switching between different adaptations, bats can maximize the extraction of their biosonar signals from the background.