Velocity as an overlooked driver in the echolocation behavior of aerial hawking vespertilionid bats.

Abstract

Moving animals must gather information at sufficient rates, detail, and range relative to their velocity while filtering this information to that essential for a given task.^1,2 Echolocators, because of their active sensory system, are exceptional models for investigating how animals filter and adjust information flow to motor patterns.^3,4 During airborne prey capture, bats adjust echolocation and, by extension, how they probe for information in distance- and context-dependent ways.^5,6,7 We investigated how sensory probing guides movement and how niche specializations shape strategies to integrate information acquisition and motion velocity. Specifically, we recorded three sympatric bats of the same foraging guild (edge-space hawkers), but different niches, as they intercepted airborne prey under identical conditions. When hawking, we find that the trawler, Myotis daubentonii, and the hawker, Pipistrellus pygmaeus, exhibit similar flight and echolocation behavior, whereas the gleaner, M. nattereri, flies slower and produces calls of lower duration and intensity, greater bandwidth and call interval, but similar beam breadth. Strikingly, these differences in echolocation behavior converge when accounting for flight speed. We show that these species move equivalent distances between call emissions and that all bats travel through their respective sonar ranges in the same time interval. Further, each echolocation call's duration is related to the two-way travel time of its sonar range, and thus velocity, the same way across species. The similarity in how these bats sample their environment relative to velocity suggests general mechanisms of information processing and conserved traits underlying auditory attention in vespertilionid bats and, perhaps, other echolocators.