A glimpse of the world through the voice of the echolocating bat.

Abstract

Bats echolocating in the natural environment face the formidable task of sorting echoes from closely spaced obstacles and prey, which may be mixed with sonar signals of nearby conspecifics. This talk will review behavioral strategies used by the big brown bat, Eptesicus fuscus, to solve such auditory scene analysis tasks. The sonar beam emission pattern of the big brown bat is directional, but broad enough to collect echo information from objects within a 60–90 deg cone, which would enable simultaneous inspection of adjacent objects. Data show, however, that bats shift their sonar gaze to inspect closely spaced objects sequentially and analyze sounds source direction and distance to track auditory objects as they fly. When bats forage in groups, they face the challenge of sorting echoes from their own calls from echoes and calls of neighboring bats. Research findings demonstrate that bats make adjustments in the spectral characteristics of calls when flying with conspecifics, and the magnitude of these changes depend on the baseline similarity of calls produced by individual bats when flying alone. These recent discoveries from studies of bat echolocation point to the general importance of an animal’s action to its analysis of natural scenes.