Offshore wind farms and seabirds

Background

German marine areas are used intensively by humans. The area used for human activities in the North Sea and Baltic Sea has increased significantly in recent years due to the construction of numerous offshore wind farms (OWP). The German government is also currently planning the expansion of large-scale OWPs; at least 70 gigawatts (GW) of offshore wind energy are to be installed in the German Exclusive Economic Zone by 2045, with around 8 GW currently in operation in the German North Sea and Baltic Sea. The area used for human activities is therefore expected to increase significantly in the future. This results in a large spatial overlap with areas that serve as feeding or resting areas for marine wildlife.

project

The project "Expansion of offshore wind energy in Germany: Effects on seabirds in the North and Baltic Seas" (OWP-Seabirds) aims to investigate in more detail how offshore wind farms in operation affect the occurrence of various seabird species. Possible effects concern individuals that use the German North Sea and Baltic Sea as a resting, wintering and/or moulting area, but also breeding birds on the coasts of the marine areas.

The potential effects of OWPs on various seabird species include shifts in distribution centres and loss of habitat due to avoidance of OWPs, fragmentation of frequently used flight routes between breeding colonies and feeding grounds, fatal collisions with the turbines, attraction by e.g. opportunities for resting on the turbines and development of new food resources due to changes in habitat structure. It was previously unknown what effect the total number of OWPs in operation in German waters has on the occurrence of seabirds and what possible effects can be expected from future expansion.

In order to answer these questions, various modelling approaches were developed as part of the project. All available data sets on the occurrence of seabirds in German waters for the period 2000-2020, from research projects, marine biodiversity monitoring and the environmental monitoring to be carried out at OWP, served as the data basis. The analyses showed that, in addition to the very sensitive species group of loons (red-throated divers - Gavia stellata and black-throated divers - Gavia arctica, Garthe et al. 2023), other, more common seabird species, in particular guillemots (Uria aalge, Peschko et al. 2024), but also fulmars (Fulmarus glacialis), northern gannets (Morus bassanus) and razorbills (Alca torda) reacted to OWPs with strong and extensive avoidance in some cases. The gull species studied so far, kittiwakes (Rissa tridactyla) and herring gulls (LarA forecast of the future effects of the planned OWP expansion revealed that around 70 % of the common guillemots occurring in the German North Sea in autumn would be affected by habitat loss if all OWP areas planned to date in the marine spatial planning were to be expanded. At this time of year, the largest populations of common guillemots are present in the German North Sea, meaning that around 2.5-3 % of the European population would be affected by habitat loss in the German North Sea alone as a result of development.

Outlook

The results of the "OWP-Seabirds" project show that various seabird species react sensitively to operating OWPs in German waters. There is therefore already evidence of significant effects from the current OWP expansion, but strong effects are to be expected from the future expansion in particular. However, in order to be able to comprehensively assess the effects of the upcoming expansion of offshore wind energy, it is of fundamental importance to carry out corresponding analyses for other seabird species in the North Sea and the seabird occurrence in the Baltic Sea. In addition, it is necessary to carry out studies on mitigation measures, possible familiarisation effects and effects at international level in order to be able to take into account the sensitivity of the various species to offshore wind farms when planning future areas.