Installation of wind farms has increased rapidly across Europe over the last two decades, as governments seek to reduce the greenhouse gas emissions associated with climate change and secure energy supplies through greater use of renewable resources. Although there is increasing evidence for climate change having a deleterious effect on avian populations (Bright et al. 2006), there is also concern that wind farms may have direct negative effects on the birds through collision mortality, decreased landscape function (barrier effects) and displacement from feeding areas (Drewitt & Langston 2006). Accurate assessment of potential cumulative impacts from multiple wind farms along a flyway is a major challenge as it requires detailed information on the birds’ migration routes. Where there is evidence of potential risk at one or more sites, specific research projects should be undertaken in order to support conclusions made within Environmental Impact Assessments (EIAs) for each development.
One such project is the satellite-tracking of Whooper Swan Cygnus cygnus migration between Great Britain and Iceland, undertaken in 2009 by the Wildfowl & Wetlands Trust (WWT) in association with COWRIE Ltd (Collaborative Offshore Wind Research into the Environment). Several of the offshore wind farms planned for Great Britain are likely to coincide with the flight paths of Icelandic-breeding swans and geese that winter in this country. There is particular concern for Whooper Swans because their large size makes them less manouvrable than other smaller species, raising the risk of them flying into the turbines; flying accidents are known to be a major cause of death for these birds (Brown et al. 1992). Moreover, as Great Britain receives 42% of the Icelandic Whooper Swan population each winter (Worden et al. 2009), it has a particular responsibility for the conservation of these birds. The study therefore aimed to provide detailed information on the swans’ migration routes and flight heights in relation to current and proposed offshore wind farm sites, particularly in relation to the large Round 3 zones identified for the North Sea and East Irish Sea.