The raster data in the geodatabase represent range-wide habitat suitability model predictions for five species of herpetofauna: gopher tortoise (Gopherus polyphemus), southern hognose snake (Heterodon simus), Florida pine snake (Pituophis melanoleucus mugitus), gopher frog (Lithobates capito), and striped newt (Notophthalmus perstriatus). Collectively, the habitat suitability rasters extend across the range of these species in the Southeast US, including areas in Louisiana, Mississippi, Alabama, Florida, Georgia, South Carolina, and North Carolina. This assessment was conducted by the USGS Cooperative Fish & Wildlife Research Unit at the University of Georgia in collaboration with other partners. Habitat suitability models were developed to 1) identify habitat features that best predict species presence and 2) estimate the amount and distribution of suitable habitat across each species’ range under current conditions. Habitat suitability models were created using comprehensive datasets of species occurrence records maintained by natural heritage programs, U.S. Fish & Wildlife Service (USFWS), U.S. Forest Service (USFS), U.S. Department of Defense (DoD), State agencies, academic researchers, and HerpMapper.org. Each species' final model included between four and nine predictors representing geospatial datasets of landscape attributes that were publicly available from various sources. These predictors included soil drainage from gridded SSURGO (raster) data from NRCS, land cover classification and canopy cover data from the National Land Cover Dataset (NLCD), fire frequency from the National Aeronautics and Space Administration MODIS data of annual fire detections and U.S. Department of Agriculture Forest Service and U.S. Department of the Interior LANDFIRE fuel disturbance data, compatible wetlands classified from USGS National Wetland Inventory database, climate data using 30-year (1981-2010) averages from the University of Idaho Gridded Surface Meteorological Data, and local relative elevation using the USGS Digital Elevation Model (DEM). The resulting rasters provide predicted habitat suitability in 30-m pixels whose values range from 0 (least suitable for the species) to 100 (most suitable). The set of five habitat suitability rasters are named using five letter codes based on the species name (e.g., Gopherus polyphemus = GOPOL). The geodatabase also includes a raster indicating large areas (> 1 square-km) whose value indicates the number of species out of five for which the area was predicted to be suitable (named "HSI_all_overlap", see accompanying publication). Habitat suitability for all species was strongly influenced by soil characteristics, land cover, and fire interval. Suitable habitat was distributed on known species strongholds, as well as private lands without known species records.
A full discussion of the compilation methodology and sources used to develop the habitat suitability data is available in the accompanying publication: Crawford, B.A., J.C. Maerz, & C.T. Moore. 2019. Expert-informed habitat suitability analysis for at-risk species assessment and conservation planning. Journal of Fish and Wildlife Management. in review.
