Last time you were outside in a park or garden, did you see any robins or ladybugs? How about mosquitoes, squirrels, or earthworms? These animals are easy to find. Other kinds of animals are not so common.

While there are billions of ladybugs in the world, some kinds of animals have only a few hundred members left. A hundred might sound like a lot, but it is really a very small number. When there are only a few hundred individuals of one kind of animal, there is a good chance the animal will die out all together, or become extinct.

A species is a kind of plant or animal. The African black rhinoceros is one kind of species. The American bald eagle is another. Scientists keep a close watch on species they think might become extinct. They divide the species up into groups based on how close they are to becoming extinct. Those animals they think are in danger of becoming extinct soon are placed on the Endangered Species list. Those animals they think may become endangered soon are placed on another list called the Threatened Species list.

Often the countries where threatened and endangered animals live pass laws that stop people from bothering the animals so that they can reproduce and increase their numbers. Many animals on the Endangered Species list live in wildlife refuges set up for their protection. Animals on the Threatened Species list are usually protected from hunting by special laws.

How Animals Become Extinct

Lots of different kinds of animals that once lived on Earth have since become extinct. Extinction is a natural process. Over time, some species thrive while others die out. How does this happen?

Let’s say that a certain species’ environment suddenly changes. Maybe it becomes colder, or wetter. Or maybe a new predator moves in, or the animals’ main food source disappears. How does the species react? It either adapts to the new environment, moves to a new environment, or dies. Remember the saber-tooth tiger from the last page? When its food source, the giant mastodon, died out, it no longer had anything to eat. Pretty soon it died out too.

Although extinction can be natural, a lot of the time human behavior causes a species to become extinct. Most animals today go extinct because they lose their habitat, or the area they live in. When trees and grasslands are cut down to make room for houses and roads, animals that live on the land have to move away. Sometimes there is nowhere for them to go, and they die.

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