Gray bats spatially segregate when navigating flight with conspecifics in complex environments

Bats are fast fliers with great maneuverability. Many species sense and communicate through echolocation, relying on acoustic signals in the environment. Bats also form large colonies, which necessitates that they fly in groups. When the group size increases or obstacles are in their flight paths, the acoustic space can become cluttered, posing a non-trivial challenge for navigation. How do they interact with their environment and conspecifics, and how do they balance social and environmental cues? Recent research has uncovered individual adaptations to calling and flight patterns when flying in the groups or avoiding obstacles. Studies also suggest coordination when foraging, as well as strategies used by the group to mitigate acoustic clutter. However, there has yet to be a study on how bats weigh different navigational tasks when flying in spatially complex environments. Here, we collected stereoscopic video data on a wild colony of gray bats, Mytotis grisescens, navigating their usual foraging flight paths in the presence of novel obstacles. We find that bats tend to stay close to a wall, but space out when flying in groups. We developed a data-informed agent-based model which revealed that their social repulsive behavior is strengthened when challenged to navigate novel obstacles.