# US wind turbine bat mortality study

> Developing situation record from CLSTR: https://clstr.news/situations/us-wind-turbine-bat-mortality-study
> Updated: 2026-11-06T11:55:43.000Z. Sources: 12. Developments: 3.

A study published in the Proceedings of the National Academy of Sciences estimates that wind turbines caused approximately 18.7 million bat fatalities across the conterminous United States between 1981 and 2024. The research indicates that annual fatalities have increased significantly due to the expansion of the wind energy sector, rising from roughly 100,000 per year two decades ago to an estimated 1.5 million annually by 2021. The study notes that the magnitude of these losses is comparable to those caused by white-nose syndrome, though the threats affect different species. Turbines primarily impact migratory species, such as hoary bats, while white-nose syndrome is more lethal to cave-roosting species.

Potential causes for collisions include bats being attracted to blade noise, mistaking turbines for trees, or failing to detect moving blades. Researchers suggest that fatalities may be higher than previous estimates because carcass monitoring can be hindered by scavengers or vegetation. To mitigate these impacts, scientists suggest that wind energy developments should avoid specific locations, such as areas near rivers, mineshafts, karst formations, or the Appalachian Mountains.

A separate two-year study of 19 wind farms in Iowa found that turbines located at the edges of wind farms experience higher estimated bat mortality rates. Researchers suggest that proximity to certain habitats and specific weather conditions, such as temperature and wind speed, may contribute to the increased risk at these perimeter locations.

## Timeline

### 2026-11-06: Iowa wind farm study finds higher bat mortality at turbine edges

Researchers studying 19 Iowa wind farms found that turbines located at the edges of wind farms have higher estimated bat mortality rates.

2 sources. https://clstr.news/cluster/wind-farm-developments-linked-to-wildlife-mortality-risks

### 2026-10-31: Wind turbines linked to rising bat mortality in US study

A major study finds that wind turbines in the US killed 18.7 million bats between 1981 and 2024, with annual deaths rising to 1.5 million by 2021 due to the wind energy boom.

7 sources. https://clstr.news/cluster/wind-turbines-linked-to-high-bat-mortality-in-united-states

### 2026-10-28: Wind turbines estimated to have killed 18.7 million bats in US

A study estimating 18.7 million bat deaths from US wind turbines since 1981 suggests annual fatalities have reached 1.5 million since 2021, highlighting significant impacts on migratory species.

3 sources. https://clstr.news/cluster/wind-turbines-estimated-to-have-killed-187-million-bats-in-us

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Cite as: US wind turbine bat mortality study. CLSTR, https://clstr.news/situations/us-wind-turbine-bat-mortality-study