Environmentalists will be surprised by the altered behaviors of migratory birds at offshore wind farms.
On land, avian species experience higher mortality rates due to collisions with massive turbine blades.
Many feared that these dangers would follow wind turbines to the vast oceans. Instead, bird navigation changed drastically, but in different ways during the day and night.
To what extent could offshore turbines in migratory pathways affect bird population numbers?
How offshore wind could change Denmark’s energy landscape
The first commercial offshore wind farm in the world was constructed in 1991.
Denmark was the pioneering nation behind this accomplishment, spearheading the modern wind sector.
Today, its installed offshore wind capacity is about 2.7 GW.
Unfortunately, this capacity is not enough to fuel the surging power consumption of digital infrastructure and heavy industry.
Rising electricity demands are necessitating a major grid expansion effort.
The Danish government established strict statutory climate goals to secure energy independence.
Domestic offshore wind capacity must be expanded to 14 GW by 2030. The total capacity for 2050 is projected to be at least 52 GW.
Achieving these goals will completely shift the regional energy landscape.
Denmark would no longer be a localized green electricity producer, but a primary exporter for mainland Europe.
Transnational grid connections will power new green hydrogen plants and industrial hubs.
But this future is only possible if thousands of new turbines are installed across the North and Baltic Seas.
This becomes problematic for overlapping marine habitats.
The hidden complexity of offshore impacts
It is undeniable that wind energy infrastructure affects the surrounding local wildlife.
However, impact predictions are far more complex at sea than on land.
Environmental assessments onshore rely on direct, visible observations that are easily mapped.
This includes tracking habitat displacement across open fields or forests and counting populations.
Conversely, the open ocean presents a massive, highly dynamic multidimensional environment.
Continuous observation of deep-sea or remote, offshore wildlife can be logistically challenging and costly.
Furthermore, the way offshore wind farms shape marine species can vary across multiple factors.
On the seafloor, buried high-voltage transmission cables affect wildlife in two ways.
The laying process alters the sediment, affecting benthic organisms, and changes food chains. Additionally, their electromagnetic fields influence bottom-dwelling species’ navigation.
The Pacific Northwest National Laboratory listed the different effects Denmark’s Nysted Offshore Wind Farm had on birds.
The peer-reviewed study is available at the National Library of Medicine.
Local migratory birds react differently to offshore wind
Unlike their onshore counterparts, offshore wind installations do not experience high-bird-collision mortality.
Researchers of the Nysted study observed arriving flocks with advanced radar systems. Species heavily focused on included common eiders, a large sea duck.
The most notable change was the altered flight paths. The difference before and after the wind farm’s construction was significant.
Before construction, approximately 48% regularly crossed the baseline zone. After construction, the probability dropped to 9%.
However, the lateral avoidance of the turbine blades differed during the day and night.
Nighttime behavior changes the navigation dynamic
The birds altered their daytime migratory behavior up to 1.9 miles away from the wind farm.
In the darkness, the ducks altered their course by only 0.6 miles.
The presence inside the industrial grid was higher at night, but their survival strategy changed.
They flew down the corridor center between the turbine rows, maximizing their distance from rotating blades.
This behavioral displacement successfully minimizes the risk of avian collisions with offshore wind projects.
However, this could present another mortality risk.
Some migratory birds that are forced to fly longer distances around wind farms burn essential energy reserves. If they cannot find a safe roosting place, the additional exertion lowers overall survival rates.
Offshore wind capacity will continue to scale up, but developers must take these ecological costs into account.
