Signature calls predict foraging success in big brown bats (Eptesicus fuscus)

Abstract

Animals foraging in the dark must simultaneously pursue prey, avoid collisions, and interact with conspecifics, making efficient non-visual communication essential. A variety of birds and mammals emit food-associated calls that inform, attract, or repel conspecifics. While echolocation by the insectivorous, aerial-hawking big brown bat (Eptesicus fuscus) has been studied extensively, communicative calls used by this species have received comparatively little research attention. We report on a rich repertoire of vocalizations produced by big brown bats in a large flight room equipped with synchronized high-speed stereo video and audio recording equipment. We also provide evidence that a specific social call, the “frequency-modulated bout” (FMB), which is emitted only by males, exclusively in a foraging context, and only when conspecifics are present, predicts the caller’s foraging success and is individually distinct. Bats were studied individually and in pairs, while sex and experience with a foraging task were experimentally manipulated. Individuals emitting a higher number of FMBs showed greater prey capture success. Following FMB emission, inter-bat distance, diverging flight, and the other bat’s distance to the prey increased. These findings highlight the importance of vocal communication for nocturnal animals mediating interactions in a fast-paced foraging setting.