Eastern Hellbender Suitable Habitat

Hellbender presence data was acquired from NatureServe and limited to points dating from 1980 to the present, with individual points adapted from the available data. Geospatial data was acquired from the U.S. Geological Survey’s National Land Cover Database (NLCD) and the Horizon Systems Corporation National Hydrography Dataset (NHD) Version 2. The study was conducted over the extent of the Appalachian LCC. Environmental variables of consideration were determined through literature review and expert advice on the species (Personal correspondence, Quinn, 2009). Hellbender presence data was sub-sampled to reduce spatial bias. Pseudo-absence points were also calculated to be within 1 km of the position of the presence points. NLCD data was reclassified to identify the key variables of investigation. NHD v2 data was applied to the attribute tables of flowline shapefiles, then rasterized to a 1km buffer around each line at a 90m resolution. The feature class data was converted into a raster to be analyzed by the statistical platform (Quinn, 2009). The data was assembled in a script based MAXENT modeling framework inside R Statistical Software, based on the maximum-entropy approach for species habitat modeling (Baldwin, 2009, Hijmans & Elith, 2013). This statistical package provides a prediction on the occupancy of a given species, given the inputs of presence data and influential environmental variables. This allows the user to produce spatial results that predict species occupancy, as well as evaluate the quality and confidence in the model (Merow et al., 2013). Multiple environmental parameters were tested to produce the model with the greatest confidence and representation of the environmental conditions most suitable for the species, given the available data and understanding of the species. The mean AUC value for the model was 0.92 and output demonstrated possible undiscovered Hellbender habitat throughout the region.