Sean Sheehan - Endangered Species

E-book published in 2015 by Encyclopdia Britannica, Inc., in association with Arcturus Publishing Limited, 26/27 Bickels Yard, 151-153 Bermondsey Street, London SE1 3HA. Britannica, Encyclopdia Britannica, and the Thistle logo are trademarks of Encyclopdia Britannica, Inc.

ISBN 978-1-62513-391-5 (U.K. e-book)

First published in 2009 by Franklin Watts

Copyright 2009 Arcturus Publishing Limited

The right of Sean Sheehan to be identified as the author of this work has been asserted by him in accordance with the Copyright, Designs and Patents Act 1988.

All rights reserved.

Series concept: Alex Woolf
Editor: Alex Woolf
Designer: Phipps Design
Picture researcher: Alex Woolf

A CIP catalogue record for this book is available from the British Library.

Dewey Decimal Classification Number: 333.9522

Picture Credits
Corbis: 5 (Yann Arthus-Bertrand), 6 (Michael and Patricia Fogden), 8 (Gustavo Gilabert/Corbis Saba), 9 (Wolfgang Kaehler), 10 (Colin McPherson), 13 (Yvette Cardozo), 16 (DLILLC), 19 (Jeffrey L Rotman), 21 (Stephen Frink), 22 (Ed Kashi), 26 (Ron Sachs/Corbis Sygma), 29 (epa), 31 (Alex Hofford/epa), 32 (Bobby Yip/Reuters), 34 (W Perry Conway), 37 (Layne Kennedy), 39 (Momatiuk/Eastcott), 41 (Roger Tidman), 43 (Paul A Souders), 45 (Torsten Blackwood/Pool/epa).

NASA: 23 (Jeff Schmaltz, MODIS Rapid Response Team, NASA/GSFC).

Shutterstock: cover bottom left (Miranda van der Kroft), cover bottom right (Tom C Amon), cover background (aliciahh), 15 (Christian Riedel), 25 (Simone van den Berg), 30 (Clive Gibson), 35 (Sam Chadwick), 36 (Pete Carron).

Cover pictures
bottom left: The gorilla lives in the tropical forests and mountains of Africa. It is threatened by habitat destruction, commercial hunting and poaching.
top right: The red-eyed tree frog is a native of lowland rainforests in Central America. They are captured for zoos and for pets and their habitat is threatened by deforestation.
background: Leopard fur. Leopards are on the Red List of endangered species, threatened by habitat loss and hunting.

Every attempt has been made to clear copyright. Should there be any inadvertent omission, please apply to the copyright holder for rectification.

Contents

It is 2025 and, despite worldwide protests, the logging of the Brazilian rainforests continues. This has caused yet another winter of floods and landslides. Rivers have become polluted and their banks destroyed in the flooding. The logging of so much of the Brazilian rainforest has wiped out an incalculable number of plants, including several that had proved useful in the treatment of cancer and other serious illnesses. Hundreds of species of animals and insects have also been wiped out. In the few isolated areas of forest that remain, animals and plants are dying as their food sources and habitats are lost. Species such as fruit-eating bats, which once played a vital role in spreading seeds in the forest, have disappeared. That makes it even harder for the forest to grow back. Amphibians such as the harlequin frog, which once provided food for predators and kept insect numbers down, are long gone. Their thin skins made them vulnerable to a disease-carrying fungus, which has spread due to global warming. The forests greatest predator, the jaguar, is gone from Brazilian forests, hunted to extinction by farmers.

The rainforest

The worlds rainforests are situated around the equator in South and Central America, Asia and Africa. Rainforests have a hot, humid climate. They once covered 14 per cent of the planet but now cover only 2 per cent. Nevertheless, they provide a habitat (an environment offering food, shade, shelter and protection) for half of all known species of flora and fauna (plants and animals). Because the rainforests are shrinking as a result of human activities, many of these species are now under threat.

What is an endangered species?

When the number of individuals in a species becomes very low and the species is at risk of dying out, it is known as an endangered species. This has happened to many species over the course of earths history, and many have suffered extinction (the death of a species). Over millions of years, as conditions on earth have changed, plants and animals have either adapted or become extinct. Change has usually happened very gradually, giving time for each species to adapt.

A section of the Brazilian rainforest has been cut down for its timber and to make space for cash crops. Similar sights can be seen in many of the worlds rainforests.

However, some changes have been so enormous and so sudden that only a few species of plants and animals survived. One such change occurred around 65 million years ago, killing off the dinosaurs. It was probably caused by a meteor colliding with the earth or an enormous volcanic eruption that led to rapid climate change. The most recent of these sudden changes was the last Ice Age, when large numbers of big animals such as the sabre-toothed tiger and the mammoth became extinct. Since the ice sheets did not reach as far as the equator, many of the rainforest animals survived.

In the last few hundred years, human behaviour has begun to create a threat of mass species extinction even more sudden and destructive than the last Ice Age. No one knows how many species have become extinct, but some scientists suggest that, as each hectare of rainforest is cleared, as many as 140 extinctions of tiny insects and plants could be occurring every day.

ENDANGERED NUMBERS

So far, scientists concerned with extinction have examined only about 40,000 of the estimated 1.5 million species of flora and fauna that exist on earth. The following percentages show how many of those are in danger of becoming extinct:

25 per cent of mammals

12 per cent of birds

33 per cent of amphibians

52 per cent of insects

51 per cent of reptiles

33 per cent of conifer trees

73 per cent of flowering plants

Some scientists estimate that half of all species currently surviving will be extinct by 2100.

This harlequin frog, an endangered creature of the Amazon rainforest, displays its warning colours to deter predators. However, this does not offer protection against threats such as pollution, fungal disease and trout, introduced to the rivers where harlequins spawn.

Ecosystems

All of the earths animals and plants depend on one another for their survival. Large predators, like tigers, need smaller animals for food. Smaller animals need plants or insects for food. Plant life depends on the large predators to keep down the numbers of grazing animals and prevent overgrazing. In this way, groups of plants and animals live in interdependent communities, which we call ecosystems. The needs of all the species within an ecosystem are held in a delicate balance. If one key species is taken out, the whole system may be threatened. In the rainforest, bats and birds distribute seeds, the harlequin frog and other amphibians keep down insect numbers, and the jaguar preys on smaller mammals that might otherwise overgraze the forest floor.

One example of the complex interdependence of species within an ecosystem involves the hyacinth macaw. This beautiful, endangered bird of the Brazilian rainforest depends on one of its own predators, the toco toucan, to provide its home. Toucans hollow out holes in tree trunks for their nests and the macaw uses abandoned toucan nests in just one rare species of tree, the manduvi tree, for its own nests. If the toucan or the manduvi tree, itself dependent on other species for pollination and seed dispersal, become extinct, the macaw will lose its habitat and follow them into extinction.