A new study by the German Offshore Wind Energy Association (BWO) confirms that migratory birds almost completely avoid wind turbines, and that the collision risk is significantly lower than previously assumed. Commissioned by its financing member companies, the BWO investigated the actual collision risk in a near-shore wind farm in northern Germany. The results provide a solid basis for the environmentally-sound expansion of offshore wind energy.
Every year, millions of migratory birds cross the North and Baltic Seas, and thus also areas with offshore wind farms. The impact of these installations on migratory birds has so far been insufficiently researched. Therefore, the BWO, together with several companies in the sector, commissioned a study to investigate the actual collision risk in a near-shore onshore wind farm in northern Germany.
The goal was to use state-of-the-art technologies to obtain precise data on evasive behaviour. This allowed previous assumptions to be verified.
The researchers analysed over 4 million bird movements over a period of 1.5 years. The data refute the previous assumption that high migration intensity automatically leads to more collisions. Therefore, blanket shutdowns during periods of heavy bird migration do not appear to be a sensible approach.
The result:
- The study demonstrated that migratory birds reliably avoided wind turbines. With over 99.8% of diurnal and nocturnal migratory birds avoiding the turbines, a significantly larger proportion than previously assumed.
- No correlation between migration intensity and collisions: Contrary to previous assumptions, the collision rate did not increase with the number of migrating birds. Even during periods of high nocturnal migration activity, very few birds flew through the rotor area.
- Technological advancement: The combination of radar and AI-based cameras represents a methodological breakthrough, enabling unprecedented accuracy in recording bird flight movements in the rotor plane. This allows for reliable conclusions to be drawn regarding collision frequency.
“The new study shows that migratory birds avoid wind turbines. This confirms that the environmentally-sound expansion of offshore wind energy works in harmony with these birds and not against them. With this research, we want to depoliticise the discussion, improve the data basis, and make decisions based on facts,” summarised BWO Managing Director, Stefan Thimm.
“We used state-of-the-art methods. AI-controlled stereo cameras determined flight activity in the rotor area, while a specialised bird radar recorded migration patterns. By comparing both datasets, we were able to precisely calculate avoidance rates. In addition, we specifically searched for collision victims. This resulted in a comprehensive picture of the actual collision risk of migratory birds at wind turbines,” commented Dr Jorg Welcker, Head of Research and Development at Bio-Consult SH GmbH & Co. KG.
The study was commissioned by the BWO. It was initiated, co-ordinated, and financed by the companies DanTysk Sandbank, EnBW AG, Iberdrola, Ørsted, RWE, Skyborn Renewables, Vattenfall, and WindMW GmbH. The study was conducted by the research and consulting firm BioConsult SH.
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