A 13-year study shows wind turbines are more deadly for bats than birds

A new study has found that migratory birds and bats are killed at higher rates during migration seasons in areas where wind turbines operate in the U.S.
Christopher McFadden
The findings could be used to help reduce bird and bat deaths in the future.


A 13-year-long study has found that bat and bird deaths from wind turbines rise appreciably during migration periods. The data collected between 2009 and 2021 covered around 30 percent of all wind turbine locations in the United States and could be used to implement strategies to protect migratory birds and bats in the future,

The study, published in the open-access journal PLOS ONE, discovered this by counting daily carcass numbers at turbine sites across recorded dates. Bats were more heavily impacted (no pun intended) by the wind turbines, with a total of 10,291 bats killed in total over the day's carcasses were tallied. Birds faired a little better, with around 2/3 fewer fatalities at 3,789.

Using the data collected, the team developed a series of computer models demonstrating that the ecoregions where wind turbine sites are built and operated correspond to the seasonal pattern of collision fatalities. As the study points out, most US facilities are located on the prairies and plains of the central and western states, where numerous species of grassland birds are year-round inhabitants and are frequently at risk of collision.

Woodland birds, on the other hand, are only impacted by these facilities during their lengthy migrations, and they exhibit two peaks in deaths that coincide with the spring and autumn migrations. Regardless of the ecoregion, bat fatalities increased from mid-June to mid-November, peaking in the late summer and fall. In the case of migratory tree bats, species found in several ecoregions tended to exhibit earlier fatality peaks in more northern ecoregions, likely a reflection of these bats' southbound migration.

It is worth mentioning that out of the 370 datasets that met the criteria for a complete search schedule, only 114 were utilized by the authors. The researchers emphasize the need for more detailed data reporting from wind facilities across the United States better to understand the patterns of bird and bat fatalities. Additionally, their findings suggest that adjusting the curtailment requirements for wind turbines based on ecoregion-specific needs could potentially increase the frequency of operation for some sites while prioritizing the protection of vulnerable bird and bat species.

“First and foremost, this study helps us understand why certain species of birds and bats are more likely to collide with wind turbines than others,” said John Lloyd, the lead author. “But it also highlights the power of collaborative research – our analysis, and the patterns it uncovered, was only possible because we could draw on data from hundreds of different studies conducted across the United States and compiled in the American Wind Wildlife Information Center,” he added.

You can view the study for yourself in the journal PLOS ONE.

Study abstract:


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