SDE Feature Class
northern Sierra Nevada foothills, Western Gray Squirrel, California, connectivity
The least-cost corridors identify the best swath of habitat available for focal species to move from one landscape block to another based on predicted suitable habitat as identified by the northern Sierra Nevada foothills wildlife connectivity project.
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].
Beier, P., D. R. Majka, and J. S. Jenness. 2007. Conceptual steps for designing wildlife corridors.
The user accepts sole responsibility for the correct interpretation of this report and the correct use of its accompanying data sets in environmental documents. The northern Sierra Nevada foothills wildlife connectivity project linkage data delineates lands likely important to the 30 focal species movement between large, mostly protected areas across the study area. It is a decision-support tool to be refined by field work and local linkage designs. DO NOT assume that lands outside Landscape Blocks or Least-Cost Corridors or Linkages are unimportant to wildlife populations or movements.