Dispersal and connectivity metamodeling

The Delmarva fox squirrel is a forest dwelling species threatened by forest fragmentation on the Delmarva peninsula. Historical data and current distributions, along with a number of translocation experiments, indicate that occupancy of forest patches by DFS is dispersal limited.  We simulated the dispersal of squirrels among 144 forest patches using a self-avoiding random walk algorithm designed for movement within multi-habitat, gridded landscapes.  Simulations recorded movement paths of successful dispersers and estimated the probability of dispersal among potential habitat patches. These data were analyzed within a graph theoretical framework to assess the relative degree of connectivity in different regions of the landscape and the location of critical landscape elements (i.e., connecting patches and corridors).  The results were compared to those using inter-patch Euclidean distances as inputs for the connectivity model.  Several bottlenecks to dispersal were identified in the simulations but not apparent from the undirected, Euclidean distance-based models. The results identify specific patches for conservation and highlight specific locations for restoration within the agricultural matrix to allow for more effective movement of squirrels across the landscape.