Wind generated electricity, the most advanced renewable technology, is promised to become an important source of energy in the near future. According to current plans, within about 10 years, wind farms with a combined output of thousands of megawatts will be installed in European seas. This means that offshore wind turbines may well become Europe’s most extensive technical intervention in marine habitats. Though the saving in fossil fuels is to be welcomed, the advent of a major extension in the number of wind farms is likely to cause major problems for nature conservation, especially birds.
European seas are internationally important for a number of breeding and resting seabird populations that are subject to special protection status. Moreover, every year tens of millions of birds cross the North Sea and the Baltic Sea on migration. The erection of offshore wind turbines may affect birds as follows: (1) risk of collision, (2) short-term habitat loss during construction, (3) long-term habitat loss due to disturbance by turbines including disturbances from boating activities in connection with maintenance, (4) formation of barriers on migration routes, and (5) disconnection of ecological units, such as roosting and feeding sites. To date, it has only been possible to estimate the impact on birds from experiences with comparatively small onshore wind turbines. To assess the actual impact of these new wind farms, detailed studies on pilot offshore wind farms are essential. It is also vital that all potential construction sites are considered as part of an integral assessment framework, so that cumulative effects can be fully taken into account. A problem in making these assessments is that there is currently a lack of good data on migration routes and flight behaviour of many of the relevant bird species.