Approaches for Preserving Endangered Species

Approaches for Preserving Endangered Species

Once the cause of a species' endangerment is known, it be-comes possible to design a recovery plan. If the cause is commercial over harvesting, regulations can be issued to lessen the impact and protect the threatened species. If the cause is habitat loss, plans can be instituted to restore the habitat. Loss of genetic variability in isolated subpopulations can be countered by transplanting individuals from genetically different populations. Populations in immediate danger of extinction can be captured, introduced into a captive-breeding program, and later reintroduced to other suitable habitat.

   All of these solutions are extremely expensive. But as Bruce Babbitt, Secretary of the Interior in the Clinton administration, noted, it is much more economical to prevent "environmental trainwrecks" from occurring than to clean them up afterwards. Preserving ecosystems and monitoring species before they are threatened is the most effective means of protecting the environment and preventing extinctions. 

Destroyed habitats can sometimes be restored

 Conservation biology typically concerns itself with preserving populations and species in danger of decline or extinction. Conservation, however, requires that there be something left to preserve; in many situations, conservation is no longer an option. Species, and in some cases whole communities, have dis-appeared or been irretrievably modified. 

The clear-cutting of the temperate forests of Washington State leaves little behind to conserve, as does converting a piece of land into a wheat field or an asphalt parking lot. Redeeming these situations requires restoration rather than conservation. 

Three quite different sorts of habitat restoration pro-grams might be undertaken, depending on the cause of the habitat loss. 

Pristine restoration

 In ecosystems where all species have been effectively removed, conservationists might attempt to restore the plants and animals that are the natural inhabitants of the area, if these species can be identified. When abandoned farmland is to be restored to prairie, how would conservationists know what to plant?

 Although it is in principle possible to reestablish each of the original species in their original proportions, rebuilding a community requires knowing the identities of all the original in-habitants and the ecologies of each of the species. We rarely have this much information, so no restoration is ever truly pristine.

 Removing introduced species

 Sometimes the habitat has been destroyed by a single introduced species. In such a case, habitat restoration involves removing the introduced species. Restoration of the once-diverse cichlid fishes to Lake Victoria will require more than breeding and restocking the endangered species. The introduced water hyacinth and Nile perch populations will have to be brought under control or removed, and eutrophication will have to be reversed. 

It is important to act quickly if an introduced species is to be removed. When aggressive African bees (the so-called "killer bees") were inadvertently released in Brazil, they remained confined to the local area for only one season. Now they occupy much of the western hemisphere.

 Cleanup and rehabilitation

 Habitats seriously degraded by chemical pollution cannot be restored until the pollution is cleaned up. The successful restoration of the Nashua River in New England is one example of how a concerted effort can succeed in restoring a heavily polluted habitat to a relatively pristine condition. 

Captive breeding programs have saved some species

 Recovery programs, particularly those focused on one or a few species, must sometimes involve direct intervention in natural populations to avoid an immediate threat of extinction. 

Case study:
 The peregrine falcon American populations of birds of prey, such as the peregrine falcon, began an abrupt decline shortly after World War H. Of the approximately 350 breeding pairs east of the Mississippi River in 1942, all had disappeared by 1960. The culprit proved to be the chemical pesticide DDT (dichlorodiphenyl-trichloroethane) and related organochlorine pesticides.
 Birds of prey are particularly vulnerable to DDT because they feed at the top of the food chain, where DDT becomes concentrated. DDT interferes with the deposition of calcium in the bird's eggshells, causing most of the eggs to break before they are ready to hatch. 

The use of DDT was banned by federal law in 1972, causing levels in the eastern United States to fall quickly. However, no peregrine falcons were left in the eastern United States to reestablish a natural population.
 Falcons from other parts of the country were used to establish a captive-breeding program at Cornell University in 1970, with the intent of reestablishing the peregrine falcon in the eastern United States by releasing offspring of these birds. By the end of 1986, over 850 birds had been released in 13 eastern states, producing an astonishingly strong recovery