The role of pinna movement for the localization of vertical and horizontal wire obstacles in the greater horseshoe bat, Rhinolopus ferrumequinum

Six Rhinolophus ferrumequinum were trained to fly through an array of vertical or horizontal wires. Obstacle avoidance performance was measured as the percentage of flights in which the bats did not touch the wires (successful flights). Bats with normal mobile pinnae scored between 70% and 90% successful flights both with vertical and horizontal wires. After surgically immobilizing the pinnae by cutting motor nerves and ear muscles, avoidance performance with vertical wires (horizontal target localization) was unchanged but the percentage of successful flights with horizontal wires (vertical target localization) decreased significantly. This demonstrates the importance of pinna movements for target localization in the vertical plane and supports the hypothesis that scanning movements with pinnae are used by Rhinolophus ferrumequinum for determination of target angle.