The most common threat to endangered animals is the destruction of their natural habitat. Deforestation one way that habitat is destroyed. Rain forests are cut down for many reasons, including the sale of lumber, clearing for agriculture, or gathering wood for fuel. Human encroachment into wild areas for development of agriculture, industry, and housing is another common cause for species endangerment. Building dams can prevent many species of fish from swimming upstream to spawn, and this disrupts their lifecycle. The construction of pipelines has a similar effect on land animals, preventing predators from accessing areas containing their prey, or isolating animals from other members of their species, thus reducing the amount of genetic material available to the population as a whole.
