Prioritizing Avian Species for Their Risk of Population-Level Consequences from Wind Energy Development

<div><p>Recent growth in the wind energy industry has increased concerns about its impacts on wildlife populations. Direct impacts of wind energy include bird and bat collisions with turbines whereas indirect impacts include changes in wildlife habitat and behavior. Although many species may withstand these effects, species that are long-lived with low rates of reproduction, have specialized habitat preferences, or are attracted to turbines may be more prone to declines in population abundance. We developed a prioritization system to identify the avian species most likely to experience population declines from wind facilities based on their current conservation status and their expected risk from turbines. We developed 3 metrics of turbine risk that incorporate data on collision fatalities at wind facilities, population size, life history, species’ distributions relative to turbine locations, number of suitable habitat types, and species’ conservation status. We calculated at least 1 measure of turbine risk for 428 avian species that breed in the United States. We then simulated 100,000 random sets of cutoff criteria (i.e., the metric values used to assign species to different priority categories) for each turbine risk metric and for conservation status. For each set of criteria, we assigned each species a priority score and calculated the average priority score across all sets of criteria. Our prioritization system highlights both species that could potentially experience population decline caused by wind energy and species at low risk of population decline. For instance, several birds of prey, such as the long-eared owl, ferruginous hawk, Swainson’s hawk, and golden eagle, were at relatively high risk of population decline across a wide variety of cutoff values, whereas many passerines were at relatively low risk of decline. This prioritization system is a first step that will help researchers, conservationists, managers, and industry target future study and management activity.</p></div

Overall priority results.

<p>The distribution of average overall priority score (a) across avian species and (b) within avian orders for 428 species that occur in the conterminous US. Higher values indicate higher priority and greater potential risk from wind facilities.</p

Overall priority assignment.

<p>Overall priority assignment.</p

The risk metrics used in the prioritization, their equations, and data required.

<p>The risk metrics used in the prioritization, their equations, and data required.</p

High priority avian species.

<p>High priority avian species.</p

Turbine risk metric distributions.

<p>Frequencies of the (a) percentage of total US fatality due to wind turbines for 166 North American bird species, (b) Fatality Risk Index for 179 North American bird species, and (c) Indirect Risk Index for 418 North American bird species.</p

Prioritization work-flow.

<p>Prioritization for each species (in this example, the ferruginous hawk) begins with the calculation of 3 turbine risk metrics and 1 conservation status metric. Then random cutoff values are repeatedly drawn to assign each metric value to a low, medium, or high category. These categories are used to determine a priority score for each iteration, which can be summarized across all iterations.</p

Turbine risk metrics by order.

<p>Box plots showing the distribution of (a) proportion of fatality caused by turbines on a log scale, (b) Fatality Risk Index, and (c) Indirect Risk Index within avian orders. Whiskers span the minimum and maximum observed values, the box encloses the middle 50%, and the horizontal line indicates the median value.</p

Supplement 1. R code used to generate the model output and figures for Assessing local population vulnerability with branching process models: An application to wind energy development.

<h2>File List</h2><div> <p><a href="branching_functions.r">branching_functions.r</a> (MD5: 210cb4aa63649268432869e36fe94a62)</p> <p><a href="plotting.r">plotting.r</a> (MD5: bd0594210ad552e9e13bfc6f537db5a8)</p> <p><a href="simulations.r">simulations.r</a> (MD5: 3724fc81ee1ccde4a11844939bf00a02)</p> </div><h2>Description</h2><div> <p> </p> <p><a href="simulations.r">simulations.r</a> -- R code necessary to run branching process models.</p> <p><a href="branching_functions.r">branching_functions.r</a> -- R code functions needed for other files.<b></b></p> <a href="plotting.r">plotting.r</a> -- R code used to plot figures for the publication.</div