Protected and rare bats regularly die at wind turbines (WT). This is why the operation of new wind turbines is temporarily curtailed during periods of high bat activity. Old wind turbines run without curtailment, however. A scientific team has now produced an exemplary estimate of bat fatality rates at such old turbines by systematically recording bat carcasses in the vicinity of the turbines. During two months, 70 bats died on average per wind turbine. Even if these figures cannot be extrapolated one-to-one to all 20,000 old turbines in Germany, there is a considerable need for action. The operation of old turbines should be adjusted to the current regulations for new turbines, the authors argue.Protected and rare bats regularly die at wind turbines (WT). This is why the operation of new wind turbines is temporarily curtailed during periods of high bat activity. Old wind turbines run without curtailment, however. A scientific team has now produced an exemplary estimate of bat fatality rates at such old turbines by systematically recording bat carcasses in the vicinity of the turbines. During two months, 70 bats died on average per wind turbine. Even if these figures cannot be extrapolated one-to-one to all 20,000 old turbines in Germany, there is a considerable need for action. The operation of old turbines should be adjusted to the current regulations for new turbines, the authors argue.