There are few controlled data with which to assess the conservation role of corridors connecting refuges. If corridors were used sufficiently, they could alleviate threats from inbreeding depression and demographic stochasticity. For species that require more resources than are available in single refuges, a network of refuges connected by corridors may allowpersistence. Finally, a cowidor, such as a riparian foresc may constitute an important habitat in its own right. A dearth of information on the degree to which different species use corridors makes it difficult to tell which of these potential advantages will be realized in any particular case. Some experimental field studies suggest that certain species will use corridors, although lack of controls usually precludes a firm statement that cowidors will prevent extinction.Corridors may have costs as well aspotential benefits. They may transmit contagious diseases, fires, and other catastrophes, and they may increase exposure of animals to predaton, domestic animals, and poachers. Cowidors also bear economic costs. For example, a bridge that would maintain a riparian corridor costs about 13 times as much per lanemile as would a road that would sever the cowidor. Also,