In the Gulf of Lion, studying migratory birds in the face of wind turbine projects

Led by the French Office for Biodiversity (OFB), Migralion focused on this strategic maritime area for birdlife, frequented or occasionally flown over by millions of individuals belonging to numerous bird species, but about which we still lack knowledge.

The Gulf of Lion is also home to one of France's first floating offshore wind farms, with three wind turbines inaugurated this summer, and 19 planned by 2031.

The four-year study combined data collected during sea campaigns, using radars on the coast and telemetry, equipping birds with miniaturized geolocation tags.

"The vulnerability maps of the seabirds studied with regard to wind risk reveal contrasting levels of vulnerability within the Gulf of Lions," she concludes.

Among the risks identified, the study establishes that large birds as well as small migratory birds frequently fly in the altitude ranges of the blades of the planned wind farms.

More generally, "spatial data on the flight height of large birds, whether migratory or marine, show a risk of probable direct (collision) or indirect (avoidance) interactions with projects under development."

The OFB is particularly concerned about the spring period, when the birds return to the North and fly mostly at an altitude of less than 500 metres: "if the crossing cannot be completed in a single night, the individuals would then find themselves at very low altitude during the day, extending their flight to the height of the wind turbine blades".

"Faced with the undeniable collapse of biodiversity, the Migralion study constitutes an essential pioneering initiative to improve the acquisition of knowledge and enable us to better reconcile major strategic issues such as the production of renewable energy and the protection of biodiversity," according to Eric Hansen, coordinating director of the Mediterranean maritime facade of the OFB.

The authors of the study call for repeat capture and telemetric monitoring campaigns on the same species now that the first wind turbines have been installed, "to understand whether the birds change their behavior in the face of these habitat modifications."

Because, they point out, "bird migration is a dynamic phenomenon and species can quickly change their behavior in response to new obstacles or changes in environmental variables."