Adaptive temporal patterns of echolocation and flight behaviors used to fly through varied-sized windows by 2 species of high duty cycle bats

As actively sensing animals guided by acoustic information, echolocating bats must adapt their vocal–motor behavior to various environments and behavioral tasks. Here, we investigated how the temporal patterns of echolocation and flight behavior were adjusted in 2 species of bats with a high duty cycle (HDC) call structure, Rhinolophus ferrumequinum and Hipposideros armiger, when they flew along a straight corridor and then passed through windows of 3 different sizes. We also tested whether divergence existed in the adaptations of the 2 species. Both H. armiger and R. ferrumequinum increased their call rates by shortening the pulse duration and inter-pulse interval for more rapid spatial sampling of the environment when flying through smaller windows. Bats produced more sonar sound groups (SSGs) while maintaining a stable proportion of calls that made up SSGs during approaches to smaller windows. The 2 species showed divergent adjustment in flight behavior across 3 different window sizes. Hipposideros armiger reduced its flight speed to pass through smaller windows while R. ferrumequinum increased its flight speed. Our results suggest that these 2 species of HDC bats adopt similar acoustic timing patterns for different tasks although they performed different flight behaviors.