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Part XVII : Human Influences on Populations Index

Extinction of Species
Some Human Activities which Modify Habitats
Introduced Species
Biodiversity
Natural Parks in France

Topic Chapters Index

 

Some definitions

Brown bearn Thoiry, France © Shirley Burchill

 

Threatened species are species which may be locally abundant but they are on the point of becoming extinct in parts of their range. The wolf in Italy or the bear in France are two examples.

 

Endangered species are species which are about to become extinct. At the moment there are over 4500 species of animals and 30,000 species of plants listed as endangered. There are probably many others which we do not know about because they are so small or so remote that scientists have not yet studied them.

 

Extinct species are species which are thought to be completely exterminated. It is sometimes difficult to confirm this. It is not always easy to verify that every last member of the species has gone. On average, from 1600 to 1900, humans exterminated one species per year. Scientists believe that at present, humans are causing the extinction of thousands of species per year - some even say the number is as high as 20,000 species per year.

 

HUMAN INFLUENCES ON POPULATIONS

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How Humans can Help

There are several ways in which humans can react and help preserve nature. Conservation, protection from hunting, breeding in captivity and preserving habitats, as well as setting up natural parks.

 

Wildlife conservation

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Wildlife conservation can help to stop extinction. Animals and plants have to be studied to find out how many there are, where they live and how often they breed. In this way, a list of endangered and threatened species can be established.

 

Protection from hunting

Species which are deliberately hunted need to be protected. This means no more hunting of that animal until its numbers recover. Or it could mean setting a limit on when and where they are hunted.

 

Breeding in captivity

If it is possible, an animal or a plant can be bred in a zoo and then released in the wild. This has been successful for saving some species. Two hundred years ago, the Hawaiian goose population was estimated at 25,000 individuals. In 1940, only 43 individuals remained. After breeding the geese in captivity and releasing them, their population is up to 3000 today.

Breeding animals in captivity is very expensive. It costs much less to control hunting or to protect the habitat where the animal lives.

 

Przewalski's horse

Przewalski's horse © Paul Billiet

A species of horse called Przewalski's horse is now extinct in the wild but zoos and parks around the world have succeeded in breeding a population of over 1500.

 

Protecting habitats needs management

It is not enough to build a fence around a piece of land and call it a nature reserve. Nature reserves and national parks need managing. Many people, such as farmers, live in national parks and other people want to visit the parks for tourism. For the system to work, humans and the protected species have to live together in harmony. In Europe, where there is very little of the natural vegetation left, traditional farming is essential to maintain a nature reserve or a national park. Another reason for management is that the nature reserve may become so successful that the protected animals grow in numbers and start to destroy their own habitat.

This is the case in the Serengeti reserve of Tanzania where elephants were so well protected from poachers that they became too numerous. To prevent the population from getting too big and destroying the park, culling became necessary. Culling is a technique of park management whereby some animals must be killed to preserve an appropriate-sized population.

 

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