Five Reasons Animals Can Become Threatened or Endangered

Habitat Loss

• Human damage to habitats is the top reason animals become endangered or threatened, Encarta Encyclopedia explains. Humans log forests, turn desirable habitats into farmland and use land to construct buildings or roads. This proves especially problematic on heavily populated islands, where the supply of timber and farmland is limited. For example, human exploitation of the forests in Madagascar for logging and farms has severely threatened the population of lemurs, according to Animal Planet. Some of these endangered species live only in Madagascar.

Foreign Species

• Foreign invasive species pose another threat. Humans and other animals can accidentally or intentionally bring species to an area they do not normally populate. Sometimes the foreign animal species will rapidly reproduce and drive native animals to extinction, either by eating them or consuming their food sources. For example, Burmese pythons have threatened indigenous bird and rodent species in southern Florida, according to ScienceDaily.

Overhunting

• Animals can also become endangered or threatened when other creatures, particularly humans and foreign invasive species, hunt and kill them excessively. Humans hunt animals for their meat, fur and sometimes horns or other body parts. The passenger pigeon and Carolina parakeet were endangered by hunting and eventually went extinct, according to the Encarta Encyclopedia. Overfishing frequently puts certain species of fish and other sea creatures, including some types of whales, on the list of endangered animals.

Climate

• Long-term changes in the weather can also threaten or endanger animals. Such changes yield sometimes unpredictable effects upon the ecosystem, potentially causing a chain reaction of disappearing food sources. Climactic changes can destroy habitats, eliminate sources of food and introduce competing predators. Many animals and fish have fled to cooler or warmer areas in recent years, according to the World Wildlife Fund. The WWF indicates that such changes interfere with the feeding activities of polar bears and right whales, among others.

Other Human-related Causes

• Human damage to the environment, particularly water pollution, has put many species on the list of endangered or threatened animals. Toxic spills, pesticides, radiation, dumping and fires can all destroy habitat or cause serious health effects, which sometimes remain hidden until animals lay eggs or give birth. Animal species may also face inadvertent harm when humans try to eliminate pests or unwanted plants.