Результаты (
английский) 2:
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Bison, snow leopards, Siberian tigers, walruses and many other animal species are threatened with extinction. The reasons for the disappearance is different, but the vast majority of the source is human activity. Firstly, the main cause of the disappearance is poaching. People are killing more and more animals because of the expensive fur. Secondly because of the development of new lands, people cut down forests, which reduces the number of cloven-hoofed animals, and they are food for predators such as the Amur tiger. Development of sea shelf entails a reduction of the ice cover. This deprives the polar bears and walruses usual habitat, and with it the food. The introduction (acclimatization) of alien species also leads to a reduction in the number and species of animals. Most native species because of the invasion "Aliens" are on the verge of extinction. There are examples of the negative impact of the American mink on the European mink, the Canadian beaver in the European, on the muskrat muskrat. However it is considered possible to introduce new species to the impoverished anthropogenic ecosystems for their balance. It is permissible, for example, the introduction of herbivorous fish - carp, grass carp - in the artificial canals, where they interfere with their overgrowing.
Other causes of decline in the number and species of animals: direct destruction to protect agricultural products and commercial species (birds of prey, marmots, pinnipeds, coyotes et al.); accidental (unintentional) destruction (on the roads, in the course of military operations, mowing grass, power lines, with the over-regulation of water flow, etc.); pollution by pesticides, petroleum and petroleum products, air pollutants, lead and other toxicants.
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