CAUSES OF ENDANGERED SPECIES
The term endangered is used by international and national organizations to define plants and animals currently in danger of becoming extinct. Although the term endangered is universally used, the definition of an endangered species is greatly varied. In most cases, the factors causing an organism to become endangered are human- related. When discussing the causes of endangered species, it is important to understand that individual species are not the only factors involved in this dilemma. Endangerment is a broad issue, one that involves the habitats and environments where species live and interact with one another. Although some measures are being taken to help specific cases of endangerment, the universal problem cannot be solved until humans protect the natural environments where endangered species dwell. Back in the fall of 1973 Congress passed the Endangered Species Act, the point of which was to identify the plants and animals in the most trouble and come up with plans for saving them. The effort has probably been as controversial as it has been successful (Institute of Advanced Studies 39). Of the more than 1,400 species designated as endangered, only 18 have recovered to the point where they’ve been taken off the list. Upon signing the Endangered Species Act on December 28, 1973, President Nixon stated “Nothing is more priceless and more worthy of preservation than the rich array of animal life with which our country has been blessed” (Environmental Protection Agency). And now that scientists have cloned the last surviving member of a rare breed of cow, some fear that the public’s sense of urgency regarding vanishing species might fade. Why not just clone more owls, the thinking goes; but that, say wildlife experts, would be only a quick fix. “Cloning would provide us with individual animals but not the home to introduce them to in the wild,” says Jeff Flocken, endangered species outreach coordinator at the National Wildlife Federation. “Whatever’s causing a species to decline, whether it’s exploitation or destruction of a habitat, would continue to put that species at risk of being exterminated” (National Wildlife Federation ).
Today there are currently 1246 species of plants and animals that are either on the endangered or threatened list in the United States and 1804 worldwide. Of the 1804 endangered species worldwide, only 975 of them have approved recovery plans (Endangered Species Coalition). When these individual cases are grouped together and studied, the same cause is threatening their existence again and again.
Rapid habitat destruction is the main reason that species become endangered. Natural changes usually occur at a slow rate, so the effects on individual species are usually slight, at least over the short term. When the rate of change is greatly speeded up, there may be no time for individual species to adapt to new conditions. The results can be disastrous. This increase in the rate of habitat destruction is directly linked to the rise in human population. As more people need space for homes, farms, shopping centers and so on, there is less living space for species that cannot adapt to changing conditions. People also affect plant and animal habitats when they take wood, oil and other products from the land.
It can be difficult for individuals to recognize the effects that humans have had on specific species. It is hard to identify or predict human effects on individual species and habitats, especially during a human lifetime. But it is quite apparent that human activity has greatly contributed to species endangerment. For example, although tropical forests may look as though they are lush, they are actually highly susceptible to destruction. This is because the soils in which they grow are lacking nutrients. It may take centuries to re-grow a forests that was cut down by humans or destroyed by fire, and many of the world’s severely threatened animals and plants live in these forests. If the current rate of forest loss continues, huge quantities of plant and animal species will disappear. ” What is man without the beasts? If all the beasts were gone, man would die from great loneliness of spirit, for whatever happens to the beasts, also happens to man. All things are connected” (Chief Sealth 1885).
Native species are those plants and animals that are part of a specific geographic area, and have ordinarily been a part of that particular biological landscape for a lengthy period of time. They are well adapted to their local environment and are accustomed to the presence of other native species within the same general habitat. Exotic species, however, are interlopers. These species are introduced into new environments by way of human activities, either intentionally or accidentally. These interlopers are viewed by the native species as foreign elements. They may cause no obvious problems and may eventually be considered as natural as any native species in the habitat. However, exotic species may also seriously disrupt delicate ecological balances and may produce a plethora of unintended yet harmful consequences.
The worst of these unintended yet harmful consequences arise when introduced exotic species put native species in jeopardy by preying on them. This can alter the natural habitat and cause a greater competition for food. Species have been biologically introduced to environments all over the world and the most destructive effects have occurred on islands. Introduced insects, rats, pigs, cats and other foreign species have actually caused the endangerment and extinction of hundreds of species during the past five centuries. Exotic species are certainly a major factor leading to endangerment.
Overexploitation is another reason species become endangered. A species that faces overexploitation is one that may become severely endangered or even extinct due to the high rate in which the species is being used. One example of this is the case of the great whales, many of which were reduced to extremely low population sizes in the mid-20th century because of unrestricted whaling. In 1982 a number of countries agreed to put a ban on commercial whaling. As a result, some whales species that used to be endangered have made great comebacks. Many other species, however, are still at risk (Washington Post 57). Some other animal species experience high rates of exploitation because of the trade in animal parts. Poaching is still common in some parts of the world but in far fewer numbers than before. Most poaching affects animals with horns or tusk that can be sold for ivory of medicinal purposes. Currently, this trade is centered in several parts of Asia where there is a strong market for traditional medicines made from items like tiger bone and rhino horn (Agricultural and Forest Meteorology 69).
Disease, pollution and limited distribution are more factors that threaten various plant and animal species. If a species does not have the natural genetic protection against particular pathogens, an introduced disease can have severe effects on that species. For example, rabies and canine distemper viruses are presently destroying carnivore populations in East Africa. Domestic animals often transmit the diseases that affect wild populations, demonstrating again how human activities lie at the root of most causes of endangerment. Pollution has seriously affected multiple terrestrial and aquatic species, and limited distributions are frequently a consequence of other threats. Populations confined to a few small areas due to habitat loss may be disastrously affected by random factors.
Center for Resource and Environmental Studies, Institute of Advanced Studies Australian National University Australia. Climate change and the maintenance of conservation values in terrestrial ecosystems. 1998
Chief Sealth (1885). National Academy of Science. (1989): 302.
Endangered Species Coalition. 14 October 2001
Ignatius, David, As temperatures rise, Washington Post, May, 1930