Meeting Abstract

100.9  Sunday, Jan. 6  Kinematics of swimming and flying big brown bats, Eptesicus fuscus – a comparative study VON BUSSE, J.R.S.*; MOSTOWY, M.; BRUCE, H.; SWARTZ, S.M.; Brown University; Brown University; Brown University; Brown University rhea_vonbusse@brown.edu

Bats are extremely maneuverable and versatile fliers. Although there has been substantial research concerning the kinematics of bat flight, it is less widely appreciated that bats are also good swimmers. Here, we ask: how do bats modify the basic movements of the wing when encountering a fluid of much greater density and viscosity than air? To explore this question, we carried out a comparison of 3D wing, hindlimb, and body kinematics in swimming and flight in the big brown bat, Eptesicus fuscus. We videographed swimming in a water tank, from above and below the water surface, carried out flight trials in a variable-speed wind tunnel, and reconstructed 3D kinematics. Two propulsion phases could be identified in the swimming stroke, and the data suggests that both forelimbs and hindlimbs contribute to the thrust production. However, the three individuals used in this study differed greatly in the timing of the propulsion and in the swimming speed. The comparison between swimming and flight data revealed that wing beat frequency is similar during swimming and slow flying. While swimming, the wrist amplitude in the stroke plane and the stroke plane angle was lower, while the span ratio and the downstroke ratio was higher than in flying, which reflects the greater importance for thrust than lift production in swimming.