Species Diversity in India
Millions of species around the world may be lost even before they are discovered. India alone has a total of 459 threatened species: 86 mammals, 70 birds, 25 reptiles, three amphibians, eight fishes, 23 invertebrates and 244 plants.

India contains a vast treasury of biodiversity in all its various biogeographic zones.

Source: WCMC

Scientists have been involved in characterizing and identifying these species and preparing checklists that would, besides being an inventory of the richness of this natural wealth, function as an important aid to conservation research and monitoring.

IUCN classification of species

Extinct
Species not definitely located in the wild during the past 50 years.

Endangered
Taxa in danger of extinction or whose survival is unlikely if the causal factors continue operating.
Taxa whose numbers have been reduced to a critical level or whose habitats have been so drastically reduced that they are deemed to be in immediate danger of extinction.
Taxa that are possibly already extinct but have definitely been seen in the wild in the past 50 years.

Vulnerable
Taxa believed likely to move into the endangered category in the near future if the causal factors continue operating.
Taxa of which most or all the populations are decreasing because of over-exploitation, extensive destruction of habitat or other environmental disturbances.
Taxa with populations that have been seriously depleted and whose ultimate security has not been assured and taxa with populations that are still abundant but are under threat from severe adverse factors throughout their range.

Rare
Taxa with small world populations that are not at present 'endangered' or 'vulnerable' but are at risk.
These taxa are usually localized within restricted geographical areas or habitats or are thinly scattered over a more extensive range.

Indeterminate
Taxa known to be endangered, vulnerable or rare but where there is not enough information to say which of the three categories is appropriate.

Out of danger
Taxa formerly included in one of the above categories, but which are now considered relatively scarce because effective conservative measures have been taken or the previous threat to their survival has been removed.

Insufficiently known
Taxa that are suspected but not definitely known to belong to any of the above categories, because of lack of information.

Critically endangered
Taxa whose number of individuals in species has been lowered by more than 80 per cent of the earlier count.