Exploitation of wind energy holds a potential for conflict with bird life. Next to changes in habitat and loss of habitat, mortality of breeding and migratory birds from collisions is globally perceived to be one of the major problems. The solutions discussed in Switzerland to reduce the number of collisions of birds migrating on a broad front included the proposition to temporarily shut down wind turbines when migration intensity is high. In order to define measures that can be integrated into the authorisation procedures for wind power projects, it is essential to understand the relationship between the number of birds theoretically exposed to collisions and the number of birds which effectively collide.
The only suitable method for determining the number of birds passing a certain location is the detection of birds using quantitative radar measurements. To our knowledge, the present study is the first one nationally and internationally that combines a systematic carcass search study with simultaneously conducted quantitative radar measurements using a radar device calibrated for bird detection.