Birds adapt flight paths to avoid offshore wind turbines, Finnish study finds

A multi-year radar study of seabird behavior at Finland’s first offshore wind farm in Tahkoluoto, Pori, shows that birds adjust their flight routes to steer clear of turbines, reducing collision risks without significant disruption to local populations, according to a report published Wednesday by wind energy firm Suomen Hyötytuuli and environmental consultancy One Planet.

The study, the first in Finland to use long-term bird radar data, tracked nearly three million flights near four of the site’s 11 turbines between 2017 and 2021. Researchers found no overall decline in bird activity after construction, though flights at rotor height decreased immediately post-installation. Over four years, flight numbers in the turbines’ closest vicinity increased annually as birds learned to avoid them.

“Birds appear to recognize turbine locations and make subtle route adjustments,” said Amanda Pasanen, lead specialist at One Planet. The only recorded collision involved a young white-tailed eagle.

Tahkoluoto’s wind farm, operational since 2017, sits in a busy migratory corridor for species like black guillemots, velvet scoters, and common scoters. While the study focused on May migration periods, researchers called for expanded monitoring during breeding seasons and autumn migrations, as well as comparisons between species.

The findings may not apply to larger future projects: planned expansions at Tahkoluoto and other Finnish offshore sites will use significantly bigger turbines. The study was funded by Ålandsbanken’s Baltic Sea initiative.