As part of the plan of the Danish government to expand off-shore wind energy production, The Ministry of Environmental and Energy, in collaboration with ELSAM (an energy consortium), initiated a three-year study of the potential conflict between the Tuno Knob off-shore with park and aquatic birds in 1994-97. Danish coastal waters support very large, internationally important concentrations of moulting, migrating and wintering sea ducks which depend on shallow water areas as major feeding habitats. Denmark is committed, in relation to international conventions and EU directives, to protect and maintain these populations of aquatic birds and such shallow coastal areas are precisely the type of areas in which future wind parks are planned.
Two general approaches were adopted for the investigation: The before-after-control-impact design (BACI) and After studies conducted around the wind park. The aim of the BACI studies was to compare bird abundance and distribution before and after the construction of the wind park and between the area presumably affected by the development and a control area. This was carried out on three spatial scales: i) conducting aerial surveys in two large zones (about 5,000 ha), Tuno Knob and Ringebjerg Sand, while controlling the total number of birds in Arhus Bay (88,000 ha). ii) conducting ground surveys of two areas of about 700-800 ha coverage at Tuno Knob and Ringebjerg Sand, using the latter as a control area and (iii) within Tuno using three subareas (160-250 ha) as controls compared to the construction area. The after experiments were conducted around the wind park with the aim of controlling the confounding effect of food supply and to establish (a) the short-term possible effects of noise and rotor movements generated by the turbines on the distribution and abundance of sea ducks and (b) the long-term scaring effect of the wind park (the impact of revolving rotors and the presence of the standing towers). Finally, an experiment was conducting in order to quantify the scaring effect, if any, of the wind park on flying sea ducks.