In order to assess the risk of bats dying at wind turbines, the acoustic activity of bats within the operating range of the rotor blades is recorded. For this purpose, ultrasonic detectors are attached to the nacelles of the mast top. In a recent analysis, a team of scientists led by the Leibniz Institute for Zoo and Wildlife Research concludes that the effectiveness of this acoustic monitoring is insufficient to reliably predict mortality risk, especially for bats at large turbines. They therefore recommend installing supplementary ultrasonic detectors at other locations on the wind turbines and developing additional techniques such as radar and thermal imaging cameras for monitoring.