Polar bears, mountain lions, and alligators are all predators brought into close contact with people as they lose their habitat to homes, farms, and businesses. These animals are simply patrolling their range, but interaction with people can be deadly. Wild animals are also spotted more frequently. Poisonous plants and fungi may grow closer to homes and schools. As development brings people deeper into a species range, they may have more exposure to wild species. Loss of habitat can also lead to increased encounters between wild species and people. Because enormous parts of the Sierra Nevada, Rocky, and Cascade mountain ranges remain undeveloped, however, mountain lions are not endangered. That means the habitat can support fewer mountain lions. As these areas expanded into the wilderness, the mountain lion’s habitat became smaller. Urban areas, such as Los Angeles, California, and Vancouver, British Columbia, Canada, grew rapidly during the 20th century. To successfully live and reproduce, a single mountain lion patrols this much territory. The mountain lion of North America, for instance, has a range of up to 1,000 square kilometers (386 square miles). Many animals have a range of hundreds of square kilometers. Loss of habitat may happen as development takes place in a species range. Species have less room to live and reproduce. As trees are cut down, this habitat is lost. So do hundreds of species of tropical birds and mammals such as monkeys. Plants such as vines, fungi such as mushrooms, and insects such as butterflies live in the rain forest canopy. Tree crowns provide habitat in the canopy, or top layer, of a rainforest. As trees are destroyed, species that depend on that tree habitat may also become endangered. Some species, such as fig trees of the rain forest, may provide habitat for other species. Development can also endanger species indirectly. The Amazon rain forest is cleared for cattle ranches, logging, and ur ban use. To “clear” a piece of land is to remove all trees and vegetation from it. In the Amazon rain forest of South America, developers have cleared hundreds of thousands of acres.

Development can eliminate habitat and native species directly. This can happen in a number of different ways. Development for housing, industry, and agriculture reduces the habitat of native organisms. Human activity can also contribute to a loss of habitat. Dinosaurs became endangered, then extinct. The dinosaurs were unable to adapt to this new, cooler habitat. The impact of the asteroid forced debris into the atmosphere, reducing the amount of heat and light that reached Earth’s surface. The hot, dry climate of the Cretaceous period changed very quickly, most likely because of an asteroid striking the Earth. Dinosaurs, for instance, lost their habitat about 65 million years ago. Loss of Habitat A loss of habitat can happen naturally. Species become endangered for two main reasons: loss of habitat and loss of genetic variation. An endangered species is a type of organism that is threatened by extinction.

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