MethodsA useful method of determining corridors is through the devel-opment of least-cost paths (Kautz et al. 2006; Larkin et al. 2004;Meegan and Maehr 2002; Penrod et al. 2006; Schadt et al.2002).This technique models the relative cost for an animal to movebetween two areas of suitable habitat (Penrod et al. 2006). Thecost distance is the prerequisite for finding the least cost path orcorridor. The cost distance functions are similar to Euclidean func-tions, but instead of calculating the actual distance from one pointto another, the cost functions determine the shortest weighted dis-tance (or accumulated travel cost) from each cell to the nearest cellin the set of source cells. The weighted distance functions apply dis-tance in cost units, not in geographic units. All weighted-distancefunctions require a source raster (end of each habitat patch) and acost raster (permeability map).