Table 1 Predictor variables important to resource selection by greater sage-grouse in Wyoming

Distance to nearest well

Distance (m) to the nearest oil or natural gas well. Data on the location of wells, as of March 2012, were obtained from the Wyoming Oil and Gas Conservation Commission. All distance covariates were calculated using the Spatial Analyst\Euclidean Distance tool in ArcMap

Distance to nearest road

Distance (m) to paved, improved un-paved, or maintained dirt roads. Two-track roads were not included. Roads were heads-up-digitized at a scale of 1:2,000 from 2006 and 2009 National Agriculture Imagery Program aerial imagery at 1-m resolution

Distance to nearest residential or agricultural structure

Distance (m) to the nearest residential or agricultural structure including houses, sheds, and barns. Structures were heads-up-digitized as described above

Distance to nearest energy-related ancillary feature

Distance (m) to the nearest infrastructure associated with energy development other than wells. Such ancillary features included compressor stations, settling ponds, and buildings. Ancillary features were heads-up-digitized as described above

Percent shrub

Estimated percent of each pixel comprising the raster surface for which the vegetation type is shrub species. The data source was the Provisional Remote Sensing Sagebrush Habitat Quantification Products for Wyoming developed by the US Geological Survey. Detailed information on development and accuracy of all vegetation layers is in (Homer et al. 2012)

Percent sagebrush

Estimated percent of each pixel comprising the raster surface for which the vegetation type is sagebrush (Artemisia spp.). See Homer et al. (2012)

Percent herbaceous

Estimated percent of each pixel comprising the raster surface that is herbaceous cover. See Homer et al. (2012)

Percent bare ground

Estimated percent of each pixel comprising the raster surface that is bare ground. See Homer et al. (2012)

Percent litter

Estimated percent of each pixel comprising the raster surface that is herbaceous litter. See Homer et al. (2012)

Estimated shrub height

Estimated pixel-wide height (cm) of shrub vegetation. See Homer et al. (2012)

Convexity 90 m

Using a digital elevation model (DEM; 1 arc-second National Elevation Dataset [NED] re-sampled to 30 m; available at http://nationalmap.gov/viewer.html), convexity was calculated as the DEM pixel value minus the average elevation within a 90 × 90 m moving window (3 × 3 pixels). The average value of elevation within the moving window was calculated using the Spatial Analyst\Local\Cell Statistics tool selecting mean as the overlay statistic

Heat load index (HLI)

Rescaling of aspect (θ; radians calculated from the NED using Spatial Analyst in GIS) from 0 to 1 oriented northeast to southwest depicting the gradient from coolest to warmest aspect using the equation of McCune and Keon (2002): HLI = 1 to cosine(θ – 45)/2

Slope

Steepness (degrees) calculated from the NED using Spatial Analyst

Terrain roughness 90 m

An index of terrain roughness calculated as the standard deviation (SD) of elevation from a DEM within a 90 × 90 m moving window (3 × 3 pixels). This covariate was calculated using the Spatial Analyst\Local\Cell Statistics tool selecting SD as the overlay statistic

Distance to nearest mesic area

Distance (m) to the nearest permanent or intermittent stream, seep, spring, impoundment, irrigation, or water discharge area. The raster image was developed from 0.3-m true-color and CIR aerial photography (2009) using Feature Analyst® 4.2 (Visual Learning Systems 2008) for ArcGIS® 10