Some bats re-enter their cave while using echolocation at very high speeds, but this behavior is poorly studied. Thermal imaging and an array of ultrasonic microphones were used to investigate the acoustic adaptations made during high-speed re-entry for single bats entering a cave. There was a significant overall effect between bat, distance to the ground, and its flight speed on pulse duration and interpulse interval (IPI). The data imply that overall bats reduce pulse duration, IPI, and bandwidth as they approach the cave and slow down, but the behavior changes among individuals.