Migratory Bats and Wind Turbine Mortality

Wind turbines kill hundreds of thousands of migratory bats annually, a significant and growing welfare concern in renewable energy expansion.

Key Facts

Wind turbines kill an estimated 600,000 to 900,000 bats annually in North America
Migratory tree-roosting bats including hoary bats are disproportionately affected
Bats die from direct blade strike and from barotrauma — internal hemorrhage from air pressure changes near turbines
Curtailment — raising the turbine start speed at night — reduces bat mortality by 50 to 90% at modest energy cost
Acoustic deterrents mounted on turbines can reduce bat approaches without significant energy loss

Welfare Considerations

Barotrauma causes internal bleeding that may not be immediately fatal, resulting in suffering before death. The scale of wind turbine bat mortality is increasing as renewable energy expands. The good news is that relatively simple operational modifications — curtailment and deterrents — dramatically reduce mortality at modest cost to energy generation.

What You Can Do

Support wind energy companies that implement bat-sensitive operating protocols as an industry standard
Advocate for regulatory requirements for bat impact assessments before wind farm siting
Donate to organizations monitoring bat mortality at wind installations and developing deterrent technology