Prioritization of avian species impacted by wind energy development
Concerns about climate change and energy independence have driven growth in renewable energy production. Wind power avoids many of the adverse effects of fossil fuel use, but because turbines displace and kill wildlife, concerns about the environmental impact of wind energy have grown. Conservationists, managers, and industry professionals need to identify species at risk of impacts from wind energy and species needing added scrutiny during the regulatory process. We present a method for prioritizing bird species based on conservation status and risk of impacts from wind energy development. To determine conservation status, we considered IUCN rankings, the federal list of endangered species, and state lists of species of greatest conservation need. We quantified turbine risk with 3 different measures: the proportion of annual mortality that is caused by wind turbines, the proportion of the population impacted by wind energy divided by an index of life history speed (Mortality Risk Index), and the proportion of the population impacted by wind energy divided by an index of specialization (Indirect Risk Index). We used 3 scenarios for categorizing species as high, medium, or low priority based on different threshold values for our conservation status and turbine risk measures.
We assessed 427 species based on conservation status and at least one measure of risk. The rankings produced by the three measures of turbine risk were more similar than would be expected by chance. The proportion of mortality due to turbines was weakly, but significantly, correlated with both the Mortality Risk Index, ρ = 0.27 (t = 3.00, df = 114, p = 0.003), and the Indirect Risk Index, ρ = 0.19 (t = 2.51, df = 150, p = 0.013). The Mortality Risk Index and the Indirect Risk Index had the same numerator, and their rankings were more similar to one another, ρ = 0.52 (t = 8.02, df = 177, p<0.001). The majority of species were considered low priority under all 3 hypothetical scenarios. A species’ priority level was not independent of its order (Fisher’s exact test, p=0.001). Although 13.3% of species were considered high priority under a scenario with conservative cut-off values, 39.1% of the diurnal birds of prey but only 3.8% of waterfowl were considered high priority. The rankings highlight the species whose current situations make them most susceptible to the adverse effects of wind energy development. The methodology we present is also applicable to other species and threats.