Biological Corridors: Form, Function, and Efficacy Linear conservation areas may function as biological corridors, but they may not mitigate against additional habitat loss

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 extinction rates (e.g., Pimmetal. 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 strategies has been the recommendation that corridors be included in conservation plans (Figure 1) to increase the connectivity of otherwise isolated patches (Meffe and Carroll 1994). The inclusion of corridors in reserve designs has become an important conservation tactic for protecting biological diversity. This strategy was motivated by theoretical and empirical observations demonstrating that increased interchange of in-