Abstract
The Altamont Pass Wind Resource Area (Altamont) near Livermore, California is the oldest and largest wind farm in the United States of America. It is known as a location of high avian mortality, especially for diurnal raptors such as the Golden Eagle (Aquila chrysaetos). Using the avian monitoring data collected at Altamont for over thirteen years (1998-2003, 2005-2011), records were analyzed of 134 golden eagle deaths caused by wind turbine collisions. All wind turbines present during the same temporal range were characterized according to turbine variables, and geographic placement characteristics. Values of turbines that killed golden eagles were compared to values of turbines that did not. It was discovered that turbines that have killed golden eagles (kill turbines) share characteristics that are significantly different from those that have not. Kill turbines are more often situated on lattice structure towers, have larger rotor blade-swept areas, are placed in less dense turbine arrays, are further away from the next nearest turbine and are less often placed on top of ridgelines compared to nonkill turbines. Finally, kill turbines are more often situated at the end of a turbine row than are nonkill turbines. The differences between kill and nonkill turbine model, hill slope, tower height, generating capacity, array diversity, row count of turbines and placement in a hill saddle were found to be not significant. These findings support, in part, earlier turbine studies at Altamont, but do not concur with all previous findings. The methods used in this study can be applied to any bird species at Altamont and at any wind resource area throughout the world. As the wind industry continues to grow, techniques used in studies such as this are an important tool that can be used to direct wildlife conservation policies.