Abstract
The Altamont Pass Wind Resource Area (APWRA) is located in central California approximately 90 kilometers (56 miles) east of San Francisco (Figure 1). Permits have been granted for 5,400 wind turbines distributed over 165 square kilometers (40,772 acres) of rolling grassland hills and valleys in the APWRA. The APWRA supports a broad diversity of resident and migratory bird species that regularly move through the wind turbine area (Orloff and Flannery 1996). Birds passing through the rotor plane of operating wind turbines are at risk of being injured or killed. Multiple studies of avian fatality at the APWRA have documented golden eagles, red-tailed hawks, American kestrels, burrowing owls, barn owls, and a diverse mix of non-raptor species that are killed each year in turbine-related incidents (Howell and DiDonato 1991, Orloff and Flannery 1996, Howell 1997, Smallwood and Thelander 2008, Altamont Pass Avian Monitoring Team. 2008a).