Biological Corridors: Form, Function, and Efficacy

H abitat loss and fragmentation are among the most pervasive threats to the conservation of biological diversity (Wilcove et al. 1986, Wilcox and Murphy 1985). Habitat fragmentation often leads to the isolation of small populations, which have higher extinctionrates (e.g., Pimm et al. 1988). Ultimately, the processes of isolation and population extinction lead to a reduction in biological diversity. Concern for this loss has motivated conservation biologists to discuss the actions that are needed to increase the effective size of local populations. Predominant among these possible str,ltegies has been the recommendation that corridors be induded in conservation plans (Figure 1) to increase the connectivity of otherwise isolated patches (Meffe and Carroll1994). The indusion of corridors in reserve designs has become an importa nt conservation tactic for protecting biological diversity. This strategy was motivated by theoretical and empirical observations demonstrating that increased interchange of in-