Viability of carcass removal as an option for offsetting the incidental take of golden eagles (Aquila chrysaetos) at wind energy facilities

Abstract

As wind energy expands to achieve the United States net zero emission goals, compensatory mitigation will be required to offset negative impacts to birds and bats. The golden eagle (Aquila chrysaetos) is particularly susceptible to collision with wind turbines but only one option for offsetting mortalities has been approved by the U.S. Fish and Wildlife Service despite many sources of anthropogenic-caused mortality. Here, we update a previously developed vehicle-collision model with empirical data and integrate a resource equivalency analysis so that removal of road-killed game animals can be used as mitigation to offset incidental mortality. We parameterized the golden eagle behavior parameters using camera-traps placed at roadside carcasses. We quantified the effects of different carcass-removal schemes based on vehicle and carcass characteristics observed for the state of Wyoming. Our model results indicate that while eagles saved per carcass removed depends on removal interval and vehicle traffic volume, carcass removal is a viable mitigation strategy; up to seven eagles could be saved per year in some counties. While some uncertainty remains about the precise credit received from each carcass removed, delaying the inclusion of additional mitigation methods prevents opportunities for conservation action. An adaptive management program could be a way forward where management and monitoring are combined to further improve estimates of mitigation credit.