Western Gray Squirrel least-cost corridors for NSNF Connectivity - CDFW [ds1016]

The northern Sierra Nevada foothills wildlife connectivity project modeled wildlife corridors for 9 focal species between 238 landscape blocks within the northern Sierra Nevada foothills and neighboring ecoregions. We followed the least-cost corridor techniques described by Beier et al. (2007). This analysis identified the least-cost corridor, or the best potential route for each species, between neighboring landscape blocks. The data needed for a least-cost corridor analysis are a resistance raster and landscape blocks. The resistance raster is the inverse of the species distribution model (SDM) output (i.e., Maxent or BioView habitat models, which rank habitat suitability across the landscape from 0-100 for each species). We identified habitat patches for each focal species within each landscape block, and connected those habitat patches using the least-cost corridor models. The least-cost corridor model does not identify barriers, risk and dispersal. We removed urban areas and areas of unsuitable/non-restorable habitat from the corridors and then inspected the corridor to make sure they were continuous. We examined the amount of predicted suitable habitat in each corridor, and measured the distance between habitat patches within each corridor to make sure it was within the maximum dispersal distance for that focal species. If the corridors did not meet these rules then habitat patches on the border of the corridor were added to meet the selection requirements. For more information see the project report at [https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=85358].