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African Wildlife – A wonder and a challenge The Problem: The Extinction Crisis: The human species, one of millions of life forms on this planet, is threatening the very existence of many other species. Biological diversity, or biodiversity, is the variety of life forms that interact to support and sustain the balance of nature. Why it Matters: Should it matter to humans that other life forms are disappearing? Many people think so. Human populations depend on plants and animals for much of their food, medicines, clothing, and shelter. We also depend on plants for oxygen and clean air. Threatened and Endangered Species: A species or subspecies is regarded as "endangered" when it is in danger of extinction throughout all or a significant part of its normal range. In the last 500 years, human activity has forced over 800 species into extinction, and there are currently 41,415 endangered species on the planet. Examples - A Snapshot of Endangered Species of Africa: Black Rhino - The black rhino has not fared so well. As recently as 1970, an estimated 65,000 black rhinos could be found throughout sub-Saharan Africa. But in eastern Africa, 90 percent of them were killed in the 1970s. Now there are fewer than 2,500 left, in pockets in Zimbabwe, South Africa, Kenya, Namibia, and Tanzania. Elephant - Demand for ivory, combined with habitat loss from human settlement, has led to a dramatic decline in elephant populations in the last few decades. In 1930, there were between 5 and 10 million African elephants. By 1979, there were 1.3 million. Lemur - No comprehensive surveys have been done, but it is estimated that there may be more than 10,000 black lemurs surviving in the wild. Black lemurs are limited to the extreme northwestern tip of Madagascar and a few outlying islands. Crocodile - The dwarf crocodile, at no more than 5 feet (1.5 m) long, is the smallest of 3 species of crocodile which occur in Africa. It is found in swamps and slow-moving streams in the Tropical rain forests of West and Central Africa. The dwarf crocodile is now regarded as rare throughout its range. Turtle - The leatherback sea turtle is a circumglobal species, meaning that it can range throughout almost all the oceans of the world. It nests on tropical beaches in the Atlantic, Indian, and Pacific Oceans. Once abundant throughout the world's oceans, all eight species of sea turtles are now threatened or endangered. Causes - Factors Contributing to Loss of Biodiversity: 1. Habitat Loss: The most common cause of endangerment is habitat loss due to urbanization and deforestation. Plants and animals need space to live and energy provided by food, just as humans do. As human population and consumption increase, wildlife habitat is converted to houses and highways. Forests are cut down for building materials, fuel, and paper. Plants and animals need space to live and energy provided by food, just as humans do. As human population and consumption increase, wildlife habitat is converted to houses and highways. Forests are cut down for building materials, fuel, and paper. Prairies and forest land are turned into crop land and grazing land for our livestock, and shopping malls stand where wetlands once existed. The damming of rivers to create hydropower has flooded river valleys, making it hard for ocean-going fish to migrate. Even if habitat is not completely destroyed, it can be fragmented or degraded so much that it can no longer support the species it once did. Many species, particularly large mammals, need large areas of habitat to survive and reproduce. Patches of forest or grassland surrounded by farms or cities, or divided by roads, will not support these species. (For more discussion of the effects of fragmentation, see Island Biogeography). 2. Overexploitation: Humans also deplete wildlife populations by capturing or killing individuals for their own use. Animals are killed for food, fur, feathers, oil, medicines, crafts, and a host of other uses. Poachers kill animals such as elephants because their ivory tusks are valuable. Animals are also shot to stop them from killing livestock, or simply for sport. Humans also deplete wildlife populations by capturing or killing individuals for their own use. Animals are killed for food, fur, feathers, oil, medicines, crafts, and a host of other uses. They are also shot to stop them from killing livestock, or simply for sport. Animal eggs are taken for food, and species are captured for pets or to use in medical experiments. Sophisticated technology allows ever-increasing numbers of animals to be captured at once, depleting seemingly limitless species like ocean fish. As the developing nations of the world accumulate more wealth, the demand for animal products grows. The international market for animals and animal parts is a huge and growing cause of wildlife endangerment. 3. Pollution: One of the ways habitat is degraded is by pollution. Pollution occurs as a result of urbanization. Creatures that depend on either freshwater or saltwater for all or part of their life cycles, like fish, frogs, marine mammals, and many invertebrates, are especially vulnerable to pollution. One of the ways habitat is degraded is by pollution. Creatures that depend on either freshwater or saltwater for all or part of their life cycles, like fish, frogs, marine mammals, and many invertebrates, are especially vulnerable to pollution. Water is polluted by things like run-off of fertilizers and pesticides from farms, oil and other chemicals from roads, and human sewage that flows untreated into rivers, lakes, and oceans. In addition to polluting waterways, we divert fresh water from rivers and lakes for irrigation, drinking water, and industrial uses. There is less water left in the rivers and lakes to dilute the polluting chemicals. Ships pollute saltwater by dumping waste. Oil spills kill large numbers of animals. Many smaller spills and leaks go relatively undetected, but their cumulative effects over the years also can injure wildlife. Water is not the only element that suffers from pollution. Factories and cars release chemicals into the air. The chemicals are deposited on land by rain, causing pollution, including what is known as acid rain. Acid rain weakens and kills plant life, decreasing the food supply for animals that eat the plants. Pesticides are another source of pollution. Farmers use pesticides to keep insects from eating crops. Pesticides remain in crops and in wild plants eaten by herbivores (plant eaters). Insects also carry pesticides. Animals that eat herbivores (like predatory birds) and insects (like birds and amphibians) get high concentrations of these chemicals in their systems. The chemicals can disrupt physical functions like reproduction in these animals. Possible Solutions: 1. Conservation Biology: The new discipline of conservation biology has developed to respond to the increased threats to biological diversity. Its main goals are to determine human impacts on other species and to develop practical solutions to reduce the extinction rate. 2. Conservation Actions: There are many ways conservation biologists are addressing the extinction crisis. These include 1) Establishing protected areas where wildlife habitat is preserved or restored 2) Developing new ways to farm, log, and graze livestock, that preserve habitat values; and many more... Questions for Thought: Society does not have the resources to save every species from human-caused extinction. How should we decide where to put our energy and resources in conserving species? Should we concentrate on the species people like best? What other criteria might we use?