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Why are so many animals endangered? Brainstorm the possibilities… Reasons for extinction: 1) Habitat destruction 2) Introduction of invasive species into their habitat 3) Pollution 4) Overhunting 5) Capture of exotic species for use as pets Habitat Destruction Losing their homes because of the growing needs of humans Habitat loss is probably the greatest threat to the variety of life on this planet today. It is identified as a main threat to 85% of all species described in the IUCN's Red List (those species officially classified as "Threatened" and "Endangered"). Increasing food production is a major agent for the conversion of natural habitat into agricultural land. Habitat Destruction Why is it happening? Forest loss and degradation is mostly caused by the expansion of agricultural land, intensive harvesting of timber, wood for fuel and other forest products, as well as overgrazing. Around half of the world's original forests have disappeared, and they are still being removed at a rate 10x higher than any possible level of regrowth. As tropical forests contain at least half the Earth's species, the clearance of some 17 million hectares each year is a dramatic loss. Introduction of Invasive Species When a new species of plant or animal is brought into an ecosystem it can become invasive, quickly taking over and killing off other species. It may also destroy an important part of the food chain causing many other species to suffer. Many scientists believe that invasive species are the second greatest threat to threatened and endangered species, behind habitat loss. It is estimated that about 42 percent of endangered and threatened species in the United States are in danger because of the effects of invasive species. Invasive Species Human actions, both intentional and accidental, are the primary means of invasive species introductions. – European colonists who wanted to make the New World more like home originally introduced many species not native to North America. – Some intentional introductions of invasive species were intended to help with problems such as erosion and pest control. An example of a plant introduced to control erosion is kudzu, a climbing, perennial vine in the pea family. Kudzu was introduced into the U.S. from Japan in 1876 at the Philadelphia Centennial Exposition, where it was promoted as an ornamental plant, forage crop and soil stabilizer. Farmers were encouraged to plant it to reduce soil erosion, until the mid-1950s when it was recognized as a pest. Kudzu plants grow about one foot per day, and smother other plants under a solid blanket of leaves. Its vines can girdle trees, killing them. Invasive Species Organisms can also “hitchhike” on recreational boats, and be introduced to a different body of water. Scientists believe that the disease MSX, a leading cause of native oyster mortality in the Chesapeake Bay, was introduced when a foreign oyster was imported to bay waters in the 1930s. Pollution Look at any ecosystem and there could be multiple forms of contamination—streams full of toxic chemicals from industrial processes, rivers overloaded with nutrients from farms, trash blowing away from landfills, city skies covered in smog. Even landscapes that appear pristine can experience the effects of pollution sources located hundreds or thousands of miles away. Pollution Pollution from humans can kill off a species This is especially true in fresh water biomes such as rivers and lakes. Sewage and run-off from industrial plants can poison the water. When one species is affected, other species can die off as well causing a chain reaction as the balance of the ecosystem is destroyed. Over Hunting For thousands of years, people have killed animals or plants just for the fun of it. Many of them do it illegally, which is called poaching. People kill animals for their fur, oil, body parts, and many other things. The tiger has been overly hunted for its bone because some people think that the bone has some magical healing power. Now the worldwide population of tiger is not doing so well. Over Hunting Many species have been hunted to extinction or to the point where they are critically endangered. One example of this is the American Bison. There were millions of bison in the Great Plains of North America until the arrival of the Europeans. Hunting was so intense that only a few hundred were left by the time the animals became protected. Fortunately, they have survived on farms and ranches and are no longer endangered. Species that live only on islands can also be easily hunted to extinction. Even the arrival of a small tribe can quickly eliminate an island species. Over Hunting What can be done? Stricter laws against poaching with greater consequences Increasing anti-poaching patrols Not buying any products/merchandise that was from illegal animal trade or from an endangered animal (this helps by making the poacher lose money) Capture of Exotic Animals Whenever people sell or exchange wild animal and plant resources, this is wildlife trade. It can involve live animals and plants or all kinds of wild animal and plant products. Why do people trade wildlife? – People trade wildlife for cash or exchange it for other useful objects for example, utensils in exchange for wild animal skins. Driving the trade is the end-consumer who has a need or desire for wildlife products, whether for food, construction or clothing. Why is wildlife trade a problem? – Wildlife trade is by no means always a problem and most wildlife trade is legal. However, it has the potential to be very damaging. Populations of species on earth declined by an average 40% between 1970 and 2000 - and the second-biggest direct threat to species survival, after habitat destruction, is wildlife trade. Capture of Exotic Animals Perhaps the most obvious problem associated with wildlife trade is that it can cause overexploitation to the point where the survival of a species hangs in the balance. Recent overexploitation of wildlife for trade has affected countless species. This has been wellpublicized in the cases of tigers, rhinoceroses, elephants and others, but many other species are affected.