What is an endangered species? It is a kind of plant or animal at risk of going extinct. Species become endangered for two main reasons. First, their habitat may disappear. The second way is if their population is too small.
Loss of Habitat
A loss of habitat can happen naturally. For example, dinosaurs lost their habitat about 66 million years ago. Scientists believe an asteroid hit the Earth. It blasted dust into the air. Less sunlight reached plants, so they died. The air grew cooler. These changes killed off the dinosaurs, experts think.
Today, humans cause a lot of habitat loss. People cause habitat loss when they clear land for farming. For example, people around the world eat a lot of beef. People near the Amazon rainforest cut down large areas of trees to make room for cows. These changes affect wild species that live in the rainforest. It may destroy the foods some animals need. There may not be safe places to raise young. Without a healthy habitat, some plants and animals may become endangered. There are indigenous, or native, people who live in the Amazon rainforest. Many of them protect the forest. But others are still cutting down trees because they can make money using the land for farming.
Climate change also causes habitat loss. Climate change is when weather patterns around the world change over many years. Since the 19th century, humans have caused the climate to change faster than normal. Burning fuels, like gas and oil, to power machines created pollution. The pollution has trapped heat around the Earth. The temperature around the world has become warmer. This can destroy habitats. For example, polar bears live on icebergs. But warmer temperatures are melting the ice. The polar bears are having trouble adjusting to these new conditions.
Loss of Genetic Variation
A population that is too small can also make a species endangered. How? Genetic variation. Genetic variations are small differences within a species. They help a species survive. Say one oak tree needs less water than another oak tree. If there is less rain, the first oak tree is more likely to live. It may give its genetic information to its seeds. Then that oak's seedlings may need less water, too.
Human actions can make genetic variation lower. One example is catching too many fish from the oceans. Fishermen are catching too many fish because more people want to eat fish. That makes the groups of wild fish smaller. This means there are not as many fish to create new young. Because of this, genetic variation shrinks.
The more genetic variation the better. It helps species survive habitat changes. It helps them survive diseases, too.
The Red List
One environmental group keeps a "Red List of Threatened Species." This list has seven levels. It tells which species are in the most trouble. Maybe the population is shrinking fast. Maybe its habitat is disappearing.
Here are the different levels.
Least Concern and Near Threatened
Least concern is one level. Species of least concern have little chance of dying out. This level includes brown bears.
A near threatened species is one that may be in trouble soon. For instance, American bison are near threatened. They were almost all killed in the 1800s. Bison lived in grasslands, but the U.S. government wanted to turn the grasslands into farms. They killed a lot of bison. Now some indigenous people are protecting the bison. The Eastern Shoshone tribe is one group of indigenous people protecting the bison. They make sure bison can live in the wild. But the number of bison is still small. This is why they are a near threatened species.
Vulnerable, Endangered and Critically Endangered
These three levels include species facing bigger trouble.
Vulnerable Species: Ethiopian Banana Frog
This small frog lives in Africa. People are cutting down its forest habitat to build homes and farms.
Endangered Species: Big Leaf Mahogany
A mahogany is a tall tree. People use it to make furniture and floors for houses. But people have cut down too many trees. That is why this species is endangered.
Critically Endangered Species: Bolivian Chinchilla Rat
This rat lives in South America. The big threat is the loss of its forest habitat. People are cutting down the forest to make farms.
Extinct in the Wild and Extinct
A species is extinct in the wild when it can no longer live in its natural home. An animal may still live in zoos or wildlife refuges, though. Or a plant may grow with special care.
Extinct in the Wild: Wyoming Toads
Wyoming toads are small amphibians. They lived in ponds in Wyoming and Colorado. There were farms near the ponds where people used chemicals to kill bugs and other pests. Rain would wash the chemicals into the water where the toads lived. This killed many wild Wyoming toads. There was also a disease that killed a lot of the wild toads.
A species goes extinct when the last of its kind dies.
Extinct: Cuban Macaw
The Cuban macaw was a tropical parrot. They lived on the island of Cuba. People hunted them and made them pets. The last one died about 150 years ago.
Protecting Endangered Species
Why is it important to know if a species is endangered? If people know, they can take action. They can pass laws to stop hunting. They may stop people from destroying important habitats. Some species have survived because humans helped.
The brown pelican is a good example. This seabird lives on the coasts of North and South America. In 1970, it was listed as endangered.
People took action. They raised baby pelicans and released them into the wild. They banned chemicals that harmed the birds. The number of brown pelicans climbed. Today, it is safe from extinction.
There are other ways people can take action. They can give money to groups that help animals. They can grow a garden with local plants. They can go to a national park. It is also important to vote for people in government who want to help animals.
