RESEARCH ARTICLE Delayed Response and Biosonar Perception Explain Movement Coordination in Trawling Bats

Animal coordinated movement interactions are commonly explained by assuming unspeci-fied social forces of attraction, repulsion and alignment with parameters drawn from ob-served movement data. Here we propose and test a biologically realistic and quantifiable biosonar movement interaction mechanism for echolocating bats based on spatial percep-tual bias, i.e. actual sound field, a reaction delay, and observed motor constraints in speed and acceleration. We found that foraging pairs of bats flying over a water surface swapped leader-follower roles and performed chases or coordinated manoeuvres by copying the heading a nearby individual has had up to 500 ms earlier. Our proposed mechanism based on the interplay between sensory-motor constraints and delayed alignment was able to rec-reate the observed spatial actor-reactor patterns. Remarkably, when we varied model pa-rameters (response delay, hearing threshold and echolocation directionality) beyond those observed in nature, the spatio-temporal interaction patterns created by the model only rec-reated the observed interactions, i.e. chases, and best matched the observed spatial pat-terns for just those response delays, hearing thresholds and echolocation directionalitie