Endangered Species

Read through the following text and sum up the reasons why different species become endangered or extinct.

READING ONE

Starter activity

Section 2. Nature Conservation

Do you keep a pet at home? Why did you decide to have a pet? Would you keep an exotic pet such as a crocodile (a snake, a monkey, a tiger cub, etc.)? Why?

There are thought to be between 5–8 million different animal and plant species in the world. Of these 1,6 million have been identified. Some parts of the world – tundra, or arid deserts – support relatively few animals and plants; others, as tropical rain forests, which contain nearly 50 per cent of all species, are extremely rich.

The world is currently losing species at a rate of about one a day. Within 20 years, it has been conservatively estimated, at least 25 per cent of all forms of wildlife will be extinct. The loss of wildlife on this scale will have dramatic and irreversible effect on the whole fabric of life. Developments in industry, medicine and particularly agriculture, are dependent on wild species.

In Britain about 1 per cent of wildlife has become extinct this century. However, hundreds of animals, birds and plants are now officially classified as endangered. 79 species of birds, 39 animals and 62 plants have had to be completely protected by law.

Thousands of species of animals and plants are endangered, and the number increases each year. Endangered animals include blue whales, some kinds of crocodiles, orangutans, rhinoceroses, snow leopards, tigers and whooping cranes. Endangered plants include running buffalo clover, Santa Cruz cypress, and many species of cactuses.

There are many threats to wild creatures. The Caspian tiger and Topi antelope are in danger of extinction because of wars in Iran and Uganda; the Bowhead whale and Koala bear because of hunting; the Ceylon elephant and Gila Monster (Arizona) because of agricultural reclamation; and the Brown Pelican and Osprey (USA) because of pesticides. Each species of plant and animal plays a part in the delicate balance of all living systems. Thus the extinction of large numbers of species threatens the survival of other living things, including human beings.

Most biologists consider a species endangered if they expect it to die off completely in less than 20 years without special efforts to protect it. Some species have small populations, but they are not endangered because their population is not decreasing or threatened.

Until the last few centuries, species became rare or died out entirely chiefly because of natural causes. Today, species become endangered primarily as a result of activities of human beings. The invention of increasingly efficient weapons enabled people to kill game with growing ease. With the help of these advances hunters have killed off some kinds of animals. People have also cleared forests, drained swamps, and dammed rivers to clear the way for agriculture and industry. These activities have seriously harmed or destroyed many habitats for wild plants and animals.

The chief reasons that species become endangered include destruction of habitat, wildlife trade, overhunting, and competition with domestic animals.

Destruction of habitat poses great threat to the survival of wild species. Most animals and plants are especially adapted to live and reproduce in a specific environment or habitat and cannot survive when it is destroyed. People damage many types of wildlife habitat when they provide space for settlement, farming, and industry. Clearing land for development and harvesting trees for timber have destroyed vast amounts of forest habitats. In some parts of the world grasslands have become barren because people have allowed their livestock to overgraze land. Coral reefs have sometimes been dynamited to obtain species of coral and tropical fish that are valued by collectors.

Tropical rainforests are being destroyed more rapidly than any other type of wild habitat. Many scientists believe that as many as 20 million hectares of tropical rainforests are burned or cleared each year. If the current rate of clearing continues, almost all the rainforests – and the species they support – will be eliminated in less than 30 years.

Wildlife trade includes the capture of animals for pets, zoos, and research and the killing of animals for their fur and other body parts. The capture of wild animals for commercial use has endangered many species. For example, Spix's macaw, a colourful parrot of Brazil, is nearly extinct in the wild because people have captured so many of the birds for private bird collectors.

Other animals are threatened by direct exploitation for luxury products. Animals have been killed in such large numbers for their fur, hides, tusks, or horns, that they are nearly extinct. The skins of crocodiles, turtles, lizards and snakes are used for bags, belts, and shoes. Elephant ivory is made into jewellery, piano keys and invested in as a precious commodity. The skins of leopards, cheetahs, wild spotted and striped cats are cut up and made into clothes, hats and rugs. Whales are exploited for their oil and meat; feathers from birds are used to make hats and fans. The powder from ground-up rhino horn (reputed to be a powerful medicine in the Far East despite clear evidence to the contrary) is now worth its weight in gold. Although these animals are now protected by law in the countries where they live, they are still poached. Poaching, for example, has seriously reduced the number of African elephants.

Overhunting has brought many species to the brink of extinction. These animals include the Caribbean manatee and many species of pheasants. A growing number of sea birds and sea mammals, including certain dolphins, have become endangered by commercial fishing. Each year, fisheries unintentionally entrap and kill thousands of such animals in their nets.

On many islands native birds, mammals, and reptiles have become endangered after people introduced domestic animals, which compete with native species for living space. Sheep, goats and cattle overgraze vegetation, eliminating habitat. Domestic cats prey on birds and small mammals. Rats escape from the holds of visiting ships and infest islands, killing small birds and their eggs.

A growing number of animal species have become extinct in the wild and
live only in captivity. Some zoos and animal research centres breed such animals and release them into protected areas with the hope of returning their offspring to the wild. In some cases the offspring can be trained to survive in the wild.

If wild species are to survive, protective measures are essential. The most important, but financially and politically the most difficult measure, is to establish worldwide wilderness areas where development is either prohibited or strictly controlled. Certain countries (USA, Indonesia) have already started and international efforts are under way. However much more needs to be done and such critically important ecological zones as Antarctica and tropical rain forests must be safeguarded.

World Book

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