When an animal species is considered endangered, it means that the International Union for Conservation of Nature (IUCN) has evaluated it as nearly extinct, which means that a majority of its population has already died off and the rate of birth is lower than the species’death rate. Today, more and more animal and plant species are on the way to extinction because of a variety of major factors that cause a species to become endangered, and as you might expect, humans play a role in quite a few of them — in fact, the biggest threat to endangered animals is human encroachment (侵入) on their habitats.
Every species needs a habitat, where an animal finds food, raises its young. Unfortunately, humans destroy animal habitats in a number of different ways: building houses, clearing forests to get lumber and to plant crops, draining rivers to bring water to those crops, and making streets and parking lots.
In addition, human development pollutes the environment with all kinds of chemicals, which destroys food sources and shelters for the creatures and plants of that area. As a result, some species die out while others are pushed into areas where they can’t find food and shelters — to make matters worse, when one animal population suffers, it affects many other species in its food web, so more than one species’population is likely to decrease.
Habitat destruction is the number one reason for animal endangerment, which is why conservation groups work hard to repair the effects of human developments — many non-profit groups like the Nature Conservancy are taking measures to clean up coastlines and establish nature preserves to prevent further harm to native environments and species around the world.
8. A species is considered endangered________.
A.when the IUCN has noticed its population change | B.when most of its population has died off |
C.when the species’ birth rate is close to its death rate | D.when the species is losing its habitat |
9. What does the underlined word “lumber” probably mean?
A.Gas. | B.Food. | C.Chemicals. | D.Wood. |
10. What is being done to protect the endangered species?
A.Calling for human development. | B.Raising money. |
C.Establishing nature preserves. | D.Educating people. |
11. What is the main idea of the passage?
A.Habitat destruction causes animal endangerment. | B.Animals die out due to environment pollution. |
C.Measures need to be taken to increase species. | D.Non-profit groups are making great contributions. |