Birds and Bats

Are Wind Turbines Dangerous To Birds and Bats?

Although wind energy benefits the environment, wind turbines and related infrastructure and operations can affect wildlife, including bats, marine mammals, and birds. The U.S. Department of Energy Wind Energy Technologies Office researches ways to improve coexistence of wind energy with wildlife.

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  • Over the past two decades, improvements in wind turbine design and wind energy project siting have greatly reduced the impact of wind energy development on birds. Today’s land-based wind turbines are larger and spaced farther apart than those in previous years, which means we need fewer of them to produce the same amount of power. Offshore turbines are even bigger. In addition, they are built to prevent birds from perching on them. Thanks to these changes, today’s wind turbines pose little hazard to most birds.

    However, as with all man-made structures, wind turbines can have adverse wildlife and environmental impacts. Birds sometimes collide with wind turbine blades, and wind farms have the potential to disrupt bird habitats. However, other man-made infrastructure and forms of human interaction (including house cats) are far more harmful(link is external).

    Bald eagle flying through a wind farm.

    To help understand wind energy’s impact on birds, researchers conduct monitoring studies at proposed and operating wind energy facilities. These studies can help inform decisions about a plant’s location, size, and layout to reduce risk to wildlife.

    This can include:

    • Conducting site surveys to identify the location of raptor nests.
    • Conducting visual surveys to document the presence and activity patterns of birds throughout the year.
    • Using field monitoring to quantify the timing and magnitude of collisions.

    The data gained from these studies can help wind farm developers and operators implement strategies that will help protect birds from wind turbines.

Monitoring Activity at Potential Sites

Monitoring at Operating Wind Energy Sites

Land-based wind farm site developers and operators follow several protocols to minimize wind energy’s environmental impact. These can include using radar and thermal cameras to monitor bird and bat activity, pausing construction when wildlife is present, and installing ultrasonic acoustic devices to discourage bats from approaching turbines.
Golden eagles and bats fly in the background as cranes erect a wind turbine next to another operating one with radar and an ultrasonic device in between
Land-based wind farm site developers and operators follow several protocols to minimize wind energy’s environmental impact. (Graphic not to scale.)
Graphic by Al Hicks, NREL

How Can We Protect Bats and Birds From Wind Turbines?

The easiest way to keep birds safe from wind turbines is to avoid building turbines in areas where birds like to fly, roost, feed, mate, and raise their families. Researchers often conduct field surveys to monitor bird activity and locate nest sites to determine potential risk.

Fortunately, wind energy site developers and operators have several strategies to understand and reduce wind energy’s impact on bats. These strategies (explained further in the sections below) include:

  • Screening a potential wind energy site for bat activity.
  • Monitoring bat mortality at operating wind energy sites.
  • Curtailing wind turbine operation (by slowing, stopping, or changing the direction of blade rotation) at times when bats are likely to be present.
  • Discouraging bats from approaching wind turbines with deterrent technologies.

Guidelines and environmental regulations for utility-scale and distributed wind energy projects also help minimize impacts on bats. For example, the U.S. Fish and Wildlife Service Wind Turbine Guidelines Advisory Committee offers Land-Based Wind Energy Guidelines(link is external).

Researchers develop ways to monitor and mitigate the impact of wind energy development on bats. These efforts are sponsored by WETO, national labs (see the Tethys database of wind energy and bats publications(link is external)), and other institutions and collaborations in the industry (like the Bats and Wind Energy Cooperative(link is external), an alliance of experts from government agencies, private industry, academic institutions).

Let’s take a closer look at each of these strategies and where they fit into the wind energy site development, construction, operation, and decommissioning process.

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  • A bat
    Whether considering a site for wind energy development or operating an existing wind energy site, it is important to consider—and strive to minimize—impacts on species like this hoary bat pictured above.
    Photo from John McGregor, Kentucky Department of Fish & Wildlife Resources

    Whether considering a site for wind energy development or operating an existing wind energy site, it is important to consider—and strive to minimize—impacts on species like this hoary bat pictured here.

    As is the case with birds, the best way to keep bats safe from wind turbines is to avoid building turbines in areas with high bat activity. Therefore, when selecting a wind energy site, developers should screen for bat activity during the preconstruction phase—before construction begins. This will help determine the potential impact a wind energy facility will have on local bats.

    Screening a potential wind energy site for bat activity involves conducting acoustic monitoring studies to identify species and activity patterns associated with seasonal, weather, and habitat conditions. It is also important to identify any environmental characteristics that may attract bats, including:

    • Trees, caves, and similar spaces to roost and raise young
    • Migration paths and stopover sites
    • Winter hibernation sites like caves, mines, and rock crevices.

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