Offshore wind farms in the North Sea are displacing wintering populations of Red-throated Divers, new research has revealed.
Previous research has found that different seabird species respond to offshore wind farms differently – they may avoid the area which can lead to habitat displacement, or they may be attracted to the area which can increase mortality via collisions with the turbines. However, it is difficult to estimate the long-term population impacts of offshore wind farms on seabird populations.
Stefan Garthe and colleagues investigated how Red-throated Diver abundance changed before and after the construction of five offshore wind farm clusters in the south-eastern North Sea. The authors used data on diver numbers from ships, aircraft, and digital aerial surveys collected during March and April between 2010 and 2017. They modelled how the density of diver populations changed within the area up to and beyond 10 km away from the wind farms.
Red-throated Divers were displaced by the construction of offshore wind farms in the North Sea (Andy Thompson).
The authors report that distribution and abundance of loons changed significantly after the windfarms were built, with a low abundance of loons in the immediate vicinity of the turbines creating a 'halo effect'. Diver numbers decreased by 94% within 1 km of the wind farms, and by 54% within 10 km. In particular, divers completely disappeared from the vicinity of two of the studied wind farm clusters. Overall, the total population estimate of loons fell by 29% from 34,865 individuals before wind farm construction to 24,672 after construction.
The team found that no other seabirds had such a significant negative reaction to the presence of the wind farms.
They suggest that the construction of the offshore wind farms will have affected how the divers forage for fish, as their movements are now restricted to smaller areas.
The findings highlight the need to minimise the impact of offshore wind farms on seabirds, while balancing this effort with the demand for renewable energy. They recommend increasing the study of cumulative effects of wind farms throughout the year across the entire region of farms.
Garthe, S, Schwemmer, H, Peschko, H, Markones, N, Müller, S, Schwemmer, P, & Mercker, M. 2023. Large-scale effects of offshore wind farms on seabirds of high conservation concern. Scientific Reports. DOI: https://doi.org/10.1038/s41598-023-31601-z