Wind power helps replace energy from coal, oil, and gas. But wind turbines, the large machines that make this power, also kill bats. A study estimates that 18.7 million bats died at US wind farms from 1981 to 2024. They came from 28 kinds of bats.
About 20 years ago, around 100,000 bats died each year. By 2021, the number reached 1.5 million as wind power grew. Many bats hit the turning blades. Scientists do not know why, but the sound may attract bats, or bats may think the machines are trees.
People can miss dead bats during searches. Animals may carry them away, and tall grass can hide them. Researchers used math to estimate deaths, including at farms without checks. Farms near rivers had more deaths, and machines with blades closer to the ground were more dangerous.
Another study looked at 141 European wind farms. Stopping machines when conditions were especially good for bats to fly could cut deaths by more than 80%. Germany has required steps to protect bats since around 2010, including rules about locations and stopping times. These can include times when bats travel between places or weather when many bats fly. However, stopping the machines this way did not reduce deaths among birds traveling between places.
