06 Track 6

Unit 3

Disappearing Animals

Chapter 1

Endangered Species

Page 41

Endangered Species

No animal species can survive indefinitely on earth. Centuries ago, species went extinct from natural causes, for example, they were unable to adapt to bad weather and other difficult conditions.

However, animals are now dying out faster than ever because of human activity. It is estimated that, until the 18th century, one species disappeared from the Earth every four years.

By the 19th century, this had increased to one species per year. By 1975, it was 1,000 species per year, and today animals are disappearing at the alarming rate of more than 40,000 species per year.

The International Union for Conservation of Nature (IUCN) has created a number of categories that describe the danger level of animal species.

Species that are completely gone are called extinct, for example, dinosaurs, and the dodo.

Species that only live in zoos or on farms, etc., fall into the category extinct in the wild. One example is the Wyoming toad.

A species is labeled critically endangered when its numbers are dangerously low. This means it is in imminent danger of dying out completely and needs protection in order to survive. The Siberian tiger and the snow leopard are two examples.

Species that have a high, but not immediate, risk of dying out are simply labeled endangered. The giant panda is a famous example.

A vulnerable species is in less trouble than an endangered one, but its numbers are still markedly declining. The cheetah and the African elephant are vulnerable species.

Animal species that are considered of least concern aren’t particularly endangered and have high numbers of individuals.

There are many factors that can cause an animal or plant species to become endangered, and one big one is the destruction of their habitats. Deforestation and soil, air, and water pollution are usually the main culprits.

For example, the population of critically endangered Sumatran orangutans is now less than 10,000 on their home island of Sumatra, Indonesia, due to deforestation and farming.

Another cause of endangerment is from humans exploiting wild animals. Uncontrolled hunting of whales in the last century, for example, resulted in many whale species becoming critically endangered.

The high demand for animal parts stems from their use in certain foods or medicines or their value as decorative objects. For example, the ivory tasks of elephants are used to make jewelry, and the price is high enough that people risked being arrested and jailed to go after these animals.

Introducing a non-native species to an environment can also cause species endangerment. A native species is one that develops naturally in a particular area and has done so for a long time.

A non-native species might be introduced into a new environment by humans, either intentionally or by accident. The brown tree snake, unknowingly brought by cargo ships stopping at Guam, has managed to kill off 10 of the 11 species of birds native to the island’s forests.

In Florida, large pet snakes such as the anaconda and the python have been released into the large Everglades swamp. The snakes have thrived in their new environment, and now compete with and may soon overwhelm the swamp’s alligators.

Organizations such as the World Wildlife Fund and the IUCN try to raise awareness of threatened animals and plants. These organizations collaborate with government agencies to save threatened or endangered species and to make new laws that will protect them.

But to really protect plant and animal species now and in the future, the public needs to be educated on the value of keeping the species alive.