COMPENSATORY BEHAVIOR OF ENSATINA-ESCHSCHOLTZII IN BIOLOGICAL CORRIDORS - A FIELD EXPERIMENT

Despite the general lack of theoretical or empirical support, biologic al corridors are assumed to mitigate the detrimental effects of habita t fragmentation by increasing landscape connectivity. To test the hypo thesis that mechanisms which affect immigration rates from a source to a target patch are affected by the presence of a corridor in an other wise unsuitable matrix, we created two strongly contrasting pathways i n replicated field experiments. One pathway type included only bare mi neral soil, the other included a potential corridor. We conducted thes e experiments with Ensatina eschscholtzii, a salamander in the family Plethodontidae. Pathways with surface organic material removed provide d a harsh environment for E. eschscholtzii, which was reflected by low er selection, shorter residency time, and higher movement rates than o n pathways that contained vegetation (corridor pathways). However, the numbers off. eschscholtzii reaching target patches connected by corri dor pathways were greater than those reaching target patches connected by bare pathways only in plots in which the matrix environment seemed most severe. Our results suggest that identifying candidate corridor areas on conservation maps might be difficult because animals may show compensatory behavioral responses to different types of habitat separ ating source and target patches. We argue that knowledge of a species' habitat-specific dispersal behaviors is critical to reliably designat ing corridors as functional components of reserve design.