22.6 Wednesday, Jan. 4 The interactive flight of bats CHIU, Chen*; SWARTZ, Sharon/M; BREUER, Kenneth/S; Brown University Chen_Chiu@Brown.edu
Bats often encounter conspecifics and/or heterospecifics in nature. Some bat species also emerge from their roosts together in large groups at dusk. Previous studies in flying/swimming animals have demonstrated that animals can take the advantage of wakes created by other individuals to fly/swim at lower energy. Therefore, we hypothesize that flying bats could interact in a manner that is energetically or aerodynamically beneficial. We investigated detailed flight kinematics of two short-tailed fruit bats, Carollia perspicillata, in the wind tunnel. Preliminary data show that the trailing bat synchronized its wing beat pattern with the leading bat when flying close together. In addition, the wing beat pattern of the trailing bat shows a small time delay compared to the leading bat’s wing beat pattern. This result suggests that the trailing bat tried to match its wing beat frequency with the leading bat. Future experiments will explore flight interactions in more detail, and extend analysis of multi-animal flight to additional species. More bat pairs will be tested in the wind tunnel under different speeds to study velocity dependence of wing beat synchronization behavior and variation among individuals. We will also probe the mechanistic basis of wing beat synchronization by analyzing differences in flight energetics between the bat that flies in the leading vs. trailing position and if the bat can take any aerodynamic advantage of group flight. In addition, we will compare two bat species, C. perspicillata and Eptesicus fuscus, characterized by different wing design and flight behavior, and look for patterns used by each species to adjust their flight behavior when flying with other bats of either the same or different species.