Consequences and Costs of Conservation Corridors

There are few controlled data with which to assess the conservation role of corridors connecting refuges. If cor- ridors 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 pre- cludes a firm statement that cowidors will prevent extinc- tion. Corridors may have costs as well aspotential benefits. They may transmit contagious diseases, fires, and other catastro- phes, and they may increase exposure of animals to preda- ton, 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 lane- mile as would a road that would sever the cowidor. Also, per- unit-area management costs may be latger for corridors than for refuges. It may be cheaper to manage some species by moving individuals between refuges rather than by buying and maintaining corridors. Each case must be judged on its own merits because spe- cies-environment interactions dtyfer. As an example, we used the case of the Florida panther (Felis concolor cotyq, of which there remain about 30. The Florida panther's potential inbreeding problems could possibly be stemmed somewhat by a corridor system, but it is far from certain that even an extensive system will save this animal, and the cost of such a system would lessen the resources that could be devoted to land acquisition and other means of aiding many other threatened species.

[1]  Daniel H. Janzen,et al.  No Park Is an Island: Increase in Interference from Outside as Park Size Decreases , 1983 .

[2]  G. Merriam,et al.  Woodland Mice in a Farmland Mosaic , 1981 .

[3]  Michael H. Smith,et al.  Management and maintenance of genetic variability in endangered species , 1980 .

[4]  J. Kushlan.  Design and management of continental wildlife reserves: Lessons from the everglades , 1979 .

[5]  R. Macarthur,et al.  The Theory of Island Biogeography , 1969 .

[6]  L. Fahrig,et al.  Habitat Patch Connectivity and Population Survival , 1985 .

[7]  M. Shaffer,et al.  The metapopulation and species conservation: The special case of the northern spotted owl , 1985 .

[8]  G. Merriam,et al.  Patchy environments and species survival: Chipmunks in an agricultural mosaic , 1985 .

[9]  N. Gotelli,et al.  Island biogeographic theory and conservation practice: Species-area or specious-area relationships? , 1984 .

[10]  J. L. Long,et al.  Introduced Birds of the World , 1982 .

[11]  F. C. James.  Environmental Component of Morphological Differentiation in Birds , 1983, Science.

[12]  M. Shaffer.  Minimum Population Sizes for Species Conservation , 1981 .

[13]  Daniel Simberloff,et al.  Refuge Design and Island Biogeographic Theory: Effects of Fragmentation , 1982, The American Naturalist.

[14]  M. Penny.  The birds of Seychelles and the outlying islands , 1974 .

[15]  Larry D. Harris,et al.  Nodes, networks, and MUMs: Preserving diversity at all scales , 1986 .

[16]  James H. Brown,et al.  Turnover Rates in Insular Biogeography: Effect of Immigration on Extinction , 1977 .

[17]  D. Simberloff,et al.  What do genetics and ecology tell us about the design of nature reserves , 1986 .

[18]  Jacques Baudry,et al.  Hedgerows and hedgerow networks in landscape ecology , 1984 .

[19]  Daniel Simberloff,et al.  The Proximate Causes of Extinction , 1986 .

[20]  R. May,et al.  Stability and Complexity in Model Ecosystems , 1976, IEEE Transactions on Systems, Man, and Cybernetics.

[21]  R. East.  Application of species-area curves to Africa savanah reserves , 1983 .

[22]  K. Ralls,et al.  Effect of inbreeding on juvenile mortality in some small mammal species , 1982, Laboratory animals.

[23]  D. Western,et al.  The future of the savannah ecosystems: ecological islands or faunal enclaves? , 1981 .

[24]  R. Forman,et al.  Corridors in a landscape their ecological structure and function , 1983 .

[25]  John Wegner,et al.  Movements by Birds and Small Mammals Between a Wood and Adjoining Farmland Habitats , 1979 .

[26]  M. Soulé,et al.  Benign neglect: A model of faunal collapse in the game reserves of East Africa , 1979 .

[27]  Carolyn Harrison,et al.  The Archipelago Approach to Conservation: Inspiring but Unproven@@@The Fragmented Forest: Island Biogeography Theory and the Preservation of Biotic Diversity. , 1984 .