Site‐specific curtailment thresholds substantially reduce bat mortality at wind energy facilities

Context: Wind energy expansion is central to climate mitigation but poses growing risks to wildlife through turbine collisions. Evidence on the effectiveness of mitigation strategies remains geographically limited and rarely tested at scale. Here we provide the first large‐scale, multi‐site evaluation of acoustic‐informed curtailment across French wind facilities, assessing whether site‐specific wind speed and temperature thresholds derived from bat activity can reduce wildlife mortality under operational conditions.

Approach and Methods: Using a dataset of mortality monitoring from hundreds of wind energy facilities, we identified sites monitored before and after a curtailment measure was applied, and control sites monitored for multiple years without curtailment. Mortality estimates were derived from raw data, correcting for biases using a standardized method to enable cross‐site comparisons. Using a before–after control‐Impact design across 16 facilities, followed by validation in a broader before–after comparison spanning 38 facilities, we disentangle curtailment effects from natural temporal variability.

Results: Site‐specific acoustic‐informed curtailment reduced fatalities of long‐ and mid‐range echolocating bats by 83% and 84%, respectively. Nocturnal migratory bird mortality was unaffected by curtailment, demonstrating that environmental thresholds optimized for bats do not extend protection to these bird species.

Synthesis and Applications: Our findings demonstrate that site‐specific operational thresholds, derived from acoustic data and meteorological conditions, substantially reduce bat mortality at wind energy facilities. As the largest standardized assessment of curtailment effectiveness and the first in Europe, this study supports the widespread adoption of site‐specific curtailment measures wherever bat mortality is detected.