Assessing carcass relocation for offsetting golden eagle mortality at wind energy facilities

As wind energy expands to achieve the United States' net zero emission goals, compensatory mitigation will be required to offset negative effects on birds and bats. The golden eagle (Aquila chrysaetos) is particularly susceptible to collision with wind turbines, but only 1 option for offsetting mortalities has been approved by the United States Fish and Wildlife Service despite many sources of anthropogenic-caused mortality. We update a previously developed vehicle-collision model with data collected during 3 winters from 2016 to 2019 and integrate a resource equivalency analysis so that relocation of road-killed game animals can be used as mitigation to offset incidental mortality. We parameterized golden eagle behaviors using motion-sensitive cameras placed at roadside carcasses. We quantified the effects of different carcass-relocation schemes based on vehicle and carcass characteristics observed for Wyoming, USA. Our model results indicate that while eagles saved per relocated carcass depends on relocation interval and vehicle traffic volume, carcass relocation is a viable mitigation strategy; up to 7 eagles could be saved each year in some counties. While some uncertainty remains about the precise credit received from each carcass relocated, 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.