According to the U.S. Endangered Species Act of 1973 animals defined as endangered species, the species is in danger of extinction throughout all or nearly all of its environment. The animals are at risk for various reasons, most often need to make changes their habitat. In fact, the destruction of habitat is the main reason. Growth of cities, mines and farms to destroy all the habitats of animal populations.
Commercial and industrial activities may reduce the land or water for animals and pollute the environment of the animal. Due to water pollution, the baiji, a species of freshwater dolphin from China, was declared functionally extinct, meaning that it is unlikely that the population can recover. Even the sound of human activity can lead to problems of animal behavior. Some experts point to Navy sonar testing, which can alter the migratory habits of whales, some as a possible explanation for the groups of whales beaching themselves.
Another factor that makes the animals become at risk from overfishing or hunting. Experts estimate that in 1600 the passenger pigeon, Birds of America, between 25-40% of birds in the United States. Since there were no laws on how many birds a hunter could kill one million have been hunted for their meat over the next 300 years. In 1921, the last passenger pigeon died in captivity, extinction of species considered to be almost entirely due to hunting. Commercial whaling has led to the near extinction of many species of whales, before most but not all, countries undertake to prohibit this practice.
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| Tigers Endangered |
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| Cats Endangered |
