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| Threats to Biodiversity |
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| Habitat loss and fragmentation, disturbance and introduction of alien species pore greatest threats to biodiversity. Exotic species have large impacts in island ecosystems. |
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| Classification of threatened species |
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| Any species of wild life likely to disappear from the world sooner or later is called a threatened species. |
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| The international union of conservation of nature and natural resources (IUCN) has classified the threatened species of wild life into 3 categories for the purpose of conservation. |
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| The classification is based on the following factors: |
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| a) The past and present distribution of the species. |
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| b) The decline in the number of population in course of time. |
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| c) Abundance and quality of natural habitat of the species. |
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| d) The biology and potential value of the species. |
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| Categories of threatened species |
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| Some endangered species of India |
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| a) Endangered (E) |
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| These are the species whose populations have decreased or habitats have been reduced to the levels that pose immediate danger of extinction. Their survival is unlikely if the causal factors threatening their existence continues. |
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| Examples: Great Indian Bustard |
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| Pink Headed Duck |
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| b) Vulnerable (V) species |
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| This category includes the species who are likely to move into the endangered category in the near future, if the causal factors continue to be operating. These are species whose populations have been seriously depleted and whose ultimate security is not assured and also those whose populations are still abundant but are under threat throughout their range. |
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| c) Rare (R) species |
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| These are species with small populations in the world. They are confined to limited areas or are thinly distributed over a more wide area. They are not at present endangered and vulnerable but are at risk. |
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| Example: Two species of Asiatic pheasants |
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| d) Threatened (T) species |
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| The term threatened is used in the context of conservation of the species which are in any one of the above 3 categories. |
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