Informing Renewable Energy Development Siting Decisions with Vertebrate Biodiversity Measures

Science Center Objects

Renewable energy development is expanding in southwestern deserts, including in Arizona. Energy developers look to resource management agencies to provide siting guidance on public lands where there might be conflicts with wildlife. Often, agency guidance considers species of conservation concern and economic importance, but information on comprehensive vertebrate biodiversity has been hard to incorporate. In this project, USGS researchers illustrate how biodiversity richness metrics for most vertebrate wildlife that can use an area and for sensitive guilds of wildlife such as bats, raptors, and migratory land birds can be incorporated into renewable energy siting decisions.

Arizona map depicting the number of bat species found across Arizona.
Bats have incurred high mortality in association with wind energy turbines. This image shows the number of species of bats in Arizona. The areas with highest number of species (23 species) are shown in red and the colors range down to the lowest number of species in blue. (Credit: Kathryn Thomas, USGS)

Background & Importance

Conflicts between wildlife and renewable energy facilities and supporting infrastructure have already been documented. Where possible, siting decisions can help minimize the threat of impact to wildlife of conservation concern and can help minimize the risk of damaging existing wildlife populations. In all cases, information during the planning stage on possible wildlife conflicts can help developers and wildlife managers determine what best practices should be implemented to minimize impact to wildlife.

The National Gap Analysis (GAP) program has developed watershed level mapping of vertebrate species habitat. GAP distribution models represent watersheds (12-digit HUC) where vertebrate species are predicted to occur based on their habitat associations. The habitat preferences for each species were extracted from a wildlife habitat relationship database that contained information from primary and published literature. 

We used these data to create biodiversity metrics across the state of Arizona. The biodiversity metrics were the richness of species predicted in 30 m x 30-meter raster cells. Our premises were: 1) vertebrate biodiversity measures can inform renewable energy siting and operations, 2) vertebrate biodiversity measures can augment agency developed guidance for renewable energy development, and 3) GAP vertebrate models can be used to develop measures of vertebrate biodiversity on a landscape scale.

Richness metrics were calculated for 511 of the 555 native vertebrate species listed by Arizona Game and Fish Department. The species were also analyzed by lifeform groups – amphibians, reptiles, birds, and mammals – and by functional groups that might be more sensitive to renewable energy development – bats, raptors, and long-distance migratory birds.

General Methods

We obtained 511 National Gap models for vertebrate species representing native terrestrial vertebrate species identified by the Arizona Game and Fish Department (AGFD) as occurring in Arizona. Using these models in ArcMap (ESRI, 10.2) we calculated total biodiversity richness for groups of vertebrate models: 1) all species, 2) by four lifeform groups (amphibians, reptiles, birds, and mammals), and 3) by three sensitive guilds (bats, raptors, and migratory land birds) across Arizona. We created GIS layers of the richness for each of the life forms and impact groups. In a second step we classified these maps by standard deviation categories to identify areas of the highest species richness. We then compared the areas of highest richness to existing guidance for renewable energy developing siting developed by the Arizona Game and Fish Department and by the US Bureau of Land Management.