Trapped within the corridor of the Southern North Sea: The potential impact of offshore wind farms on seabirds

The cuneiform southernmost part of the North Sea is an important corridor for seabird migration. An estimated total of 1-1.3 million seabirds may fly through the area each year. The great majority (40-100%) of the flyway population of great skua and little gull use the Strait of Dover to leave the North Sea, as well as 30-70% of the population of terns and lesser black-backed gulls. In addition 10-20% of the red-throated divers and great crested grebes may pass through this bottleneck. Except for great skua, all other species are mainly found in inshore areas (i.e. within 20 km of the shoreline), where the first generation of wind farms will be located. At present, very little is known about the impact of offshore wind turbines on seabirds. Being k-selected species, seabirds are extremely vulnerable to human impacts that affect adult survival. Because of this, and because of a major lack of information on nocturnal migration of seabirds and their reaction towards offshore structures like clusters of wind turbines, great care must be taken. New developments that might have a detrimental impact on resident as well as migrating seabirds must be carefully investigated, especially in this bottleneck area.