Abstract
We recorded the flight altitudes of birds at sea around Ike-Shima Island, southwestern Japan, from November 2009 to January 2011, to identify bird species with a high potential risk of collision with the blades of proposed offshore wind turbines. The species that frequently flew at altitudes within the height range for the rotor-swept area of wind turbines (30-150m), and which therefore may have a high collision risk, are Japanese Cormorant Phalacrocorax capillatus, Herring Gull Larus schistisagus, Osprey Pandion haliaetus, Black Kite Milvus migrans and Jungle Crow Corvus macrorhynchos. On the other hand, bird species with a lower risk of collision were found to include Streaked Shearwater Calonectris leucomelas, Brown Booby Sula leucogaster and Black-tailed Gull L. crassirostris, which flew at lower altitudes than the height range of the rotor-swept area, and Passerine species, which flew at higher altitudes.
