Abstract
Environmental impact assessment allows for compensation of environmental injuries in the form of resource-based restoration projects. Given that compensation is a desired policy at a given site, this study suggests an interdisciplinary scaling method (Resource Equivalency Analysis) that relies on a non-monetary bird-year metric to quantify and value the impact on human welfare from ecosystem service loss. The lost value associated with white-tailed eagle (Haliaeetus albicilla) turbine collisions at the Smøla wind-power plant (debit) in central Norway is compensated through white-tailed eagle electrocution-prevention measures at nearby power lines (credit), scaled using the same bird-year metric. We found that 172 actual and projected white-tailed eagle turbine collisions (2005–2027) led to a debit of 3,454 discounted bird-years, which captures lost life expectancy discounted to present value. Field searches indicated that annual white-tailed eagle electrocution mortality per electric distribution pole (or pylon) at Smøla ranges from 0.002 to 0.014 (2009–2011). We suggest that retrofitting between 348 and 2,209 pylons at a present-value cost of US$1.2–7.9 million (2011 at 3%) will provide equivalent value and thus compensate the public for their welfare losses. Improved electrocution probability models will improve cost-effectiveness of retrofitting as a compensatory measure. Although Resource Equivalency Analysis may provide an approach for scaling a biodiversity offset, it cannot address the inevitable environmental trade-offs required in assessing the social profitability of choosing to compensate at a particular site.