New research, just published in the journal Ringing & Migration, has used state of the art tracking technology to investigate how one of Britain's largest ducks, the Shelduck, interacts with offshore wind turbines during their migration across the North Sea. Their findings reveal - for the first time - the length, speed and flight heights of this journey.
Offshore wind farms are a key part of many governments’ strategies to reduce carbon emissions and mitigate climate change impacts. However, it is important to understand how they might affect wildlife. The risk of colliding with wind turbines, is a particular concern to migratory species travelling across the sea, and there is also a potential increased energetic cost if wind farms act as a barrier that migrating birds must fly around. The majority of British and Irish Shelduck undergo a 'moult migration' to the Wadden Sea, which runs along the coasts of the Netherlands, Germany and Denmark. They make this journey every year in late summer, after they have finished breeding. Once there, they replace their old and worn out feathers and become flightless in the relative safety that the Wadden Sea offers, before returning to Britain when their moult is complete. However, in journeying to and from the Wadden Sea, Shelduck must cross the North Sea and navigate its growing number of wind farms en route.
Scientists from the British Trust for Ornithology (BTO) used state of the art tags to track four Shelduck from the Alde-Ore Estuary Special Protection Area on the Suffolk coast to the Wadden Sea. Each bird took a separate route across the North Sea, and used previously unreported stopover sites in the Dutch Wadden Sea, before continuing on to moult sites in the Helgoland Bight off the coast of Germany. Intriguingly, one bird travelled back and forth between the Dutch and German Wadden Seas four times, adding an extra 1,000 km to its migratory journey. The reasons why remain a mystery.
Ros Green, Research Ecologist at BTO and lead author on the paper, said, “Having a working knowledge of species’ migratory movements is an essential first step in understanding the risks that offshore wind farms may pose to populations of Shelduck and other species. Further, our tags provided data on Shelduck flight speeds and height, giving additional vital information on the magnitude of the risks posed by developments.”