Europe is racing to expand its offshore wind capacity, with the North Sea at the heart of ambitious plans to deliver 100 gigawatts (GW) of joint projects by 2050. The Hamburg Declaration, signed by ten countries including Belgium, Denmark, France, Germany, Iceland, Ireland, Luxembourg, the Netherlands, Norway, and the UK, aims to mobilise €1 trillion in capital and turn the North Sea into the world's largest clean energy reservoir. But as turbines multiply, so do questions about their impact on the millions of birds that cross these waters each year.
Most research on bird collisions with turbines has focused on land-based wind farms, where carcasses can be found and counted. At sea, however, the task is far more difficult: collisions often happen at night, in poor visibility, and any remains are quickly lost to the waves. Until now, estimates of offshore bird mortality have relied heavily on theoretical models, leaving a significant gap in our understanding.
Thermal cameras and AI take on the North Sea
A new year-long pilot study, initiated by the energy company Vattenfall and carried out at the Hollandse Kust Zuid offshore wind farm in the Dutch North Sea, has sought to fill that gap. Researchers from Wildlife Imaging Systems (WIS) and Wageningen University & Research (WUR) installed 16 thermal cameras on a single turbine, covering all angles and operating 24 hours a day. Combined with artificial intelligence, the system was able to detect and interpret bird movements both day and night, even in fog or rain.
Over nearly a year of monitoring, covering both spring and autumn migration seasons, the system identified 22 possible bird collisions. Of these, two were confirmed and one was considered highly probable. The study does not claim that collisions are rare, nor that results from one turbine can be applied across the entire North Sea. Its primary aim was to test the technology's performance under real offshore conditions.
“Safeguarding biodiversity is an important part of the energy transition,” says Karen Krijgsveld, a bird ecology researcher at Wageningen University & Research. “On land, we already know quite a lot about when and why birds collide with turbines, and which species are most at risk. As offshore wind energy continues to expand, we need to develop that same understanding at sea.”
Jesper Kyed Larsen, a bioscience expert at Vattenfall, adds: “Until now, estimates of offshore bird collisions were mainly based on theoretical models. At sea, it's extremely difficult to verify fatalities because there are no remains to recover. This study demonstrates how we can get the empirical data needed to improve collision estimates and secure efficient mitigation measures.”
Consistent findings across Europe
The results echo earlier research. A study by the German Offshore Wind Energy Association (BWO) analysed more than four million bird movements over one and a half years using radar and AI-based cameras, finding that more than 99.8 per cent of migratory birds reliably avoided the turbines. Similarly, Vattenfall's own study at an offshore wind farm near Aberdeen, Scotland, which ran from June 2023 to December 2024, examined 2,007 bird flight paths and found no collisions at all.
These findings offer some reassurance, but conservationists warn that the picture is not complete. Of the 26 seabird species that breed on the UK's coastlines and islands, ten are already on the endangered list. The cumulative effect of thousands of turbines across the North Sea, combined with other pressures like climate change and habitat loss, could still pose a significant threat.
One promising mitigation measure comes from the land-based Smøla wind farm in Norway, where painting a single blade on each of its 68 turbines black reduced avian fatalities by 70 per cent. However, some critics argue that making turbines more visible could disrupt migration patterns, forcing birds to fly longer routes and expend more energy, which could be especially harmful for those returning to feed chicks.
As Europe pushes ahead with its offshore wind ambitions, the need for accurate, empirical data on bird collisions has never been greater. The thermal camera approach developed in the North Sea could become a standard tool for monitoring and mitigating the impact of turbines on migratory birds, helping to ensure that the continent's clean energy transition does not come at the cost of its avian biodiversity.
