Unlocking the mysteries of biosonar use and foraging behaviour in wild bats with on-board acoustic recording tags

ABSTRACT Since the discovery of biosonar by Griffin in the 1940s, laboratories have conducted detailed experiments on how bats produce and modify their biosonar calls, as well as on how they detect and process self-generated echoes when orienting and hunting in flight rooms. The combination of recording the calls of bats and the ease of keeping and training bats in captivity has made bat biosonar one of the most extensively studied sensory systems under controlled laboratory conditions. While such settings are ideal for testing specific hypotheses, they are less useful for understanding how bats use echolocation to solve biologically relevant tasks in their evolutionary environment. However, field studies investigating bat biosonar in their natural habitat have been challenging because of the bats' small size, nocturnal lifestyle and fast flight speeds. Despite labour-intensive field efforts to describe and categorise echolocation signals across all families of this diverse mammalian order in the wild, we still lack a detailed understanding of bat biosonar and foraging behaviour in their natural world. Recent technological advancements have enabled the development of small dataloggers that can record the echolocation and foraging behaviour of wild bats. These devices allow us to record the sensory and movement behaviour directly from the perspective of the bats as they engage in their natural behaviours. Conducting biologging field-based experimental studies in this speciose order is thereby increasingly accessible and may provide a framework for understanding the sensory ecology and foraging behaviour of wild bats in a changing world.