Dynamics of the echolocation beam during prey pursuit in aerial hawking bats

Many insects have evolved ultrasonic ears to detect and evade hunting bats, performing dramatic escape maneuvers in response to intense ultrasound. Presumably as a response, some bats broaden their echolocation beam in close proximity to insects to keep track of them at large off-axis angles. Here, we investigated if beam broadening is a general property of echolocation when hunting moving prey. The results show that emballonurid bats ensonify a wide area during pursuit, not by broadening the beam but by emitting high-intensity calls throughout pursuit. Thus, beam broadening is not a general property of echolocation, but we hypothesize that maintaining a broad acoustic field of view is crucial for all echolocators hunting moving prey.