Wind turbines are increasingly established throughout Europe and North America with often fatal consequences for wildlife, most importantly bats and birds. Yet, it is often unknown over what geographical distances wind farms are affecting animal populations. Based on stable hydrogen isotopes in fur, we assessed the geographic provenance of bats killed in summer and autumn at German wind turbines. We found that killed Pipistrellus nathusii originated from Estonia or Russia, and Pipistrellus pipistrellus from more local populations. Noctule bats (Nyctalus noctula) and Leisler’s bats (Nyctalus leisleri) were of Scandinavian or northeastern origin. Our isotopic geo-location reveals that wind turbines kill bats not only of sedentary local populations but also of distant populations, thus having potentially a negative impact beyond political borders; an observation that calls for international regulations for implementing mitigation measures to prevent large-scale detrimental effects on endangered bat populations.