Avian Risk Behavior and Fatalities at the Altamont Wind Resource Area: March 1998 to February 1999

Since 1981, more than 7,000 wind turbines have been installed in the Altamont Wind Resource Area in north-central California. Currently, about 5,000 turbines are operating. Past research efforts demonstrated that wind turbines frequently kill birds, especially raptors. Little is known about the specific flight and perching behaviors by birds near wind turbines. A better understanding of theseinteractions may one day yield insights on how to minimize bird fatalities. This Phase I progress report summarizes research findings obtained at 20 study plots totaling 785 turbines of various configurations and conducted between March 1998 and February 1999. We examined bird use and behaviors and collected data on fatalities at the same turbines throughout the course of our surveys. Wecompleted 745 30-minute point counts (1,702 bird observations) that quantified bird risk behaviors and bird use of the study plots. The four most frequently observed bird species were red-tailed hawks, common ravens, turkey vultures, and golden eagles. During the same period, we recorded 95 bird fatalities. Raptors represent 51% (n=49) of the kills found. The data indicate that the relativeabundance of species observed does not predict the relative frequency of fatalities per species. Phase II of the research is underway.