Threatened Species

The World Conservation Union, formerly known as the International Union for the Conservation of Nature and Natural Resources (IUCN), maintains detailed records and publishes lists of species at risk of extinction.

Parameters for Assessment

Species are evaluated and categorised based on four primary factors:

1. Present and past distribution.
2. Decline in population numbers over time.
3. Abundance and quality of the natural habitat.
4. Biology and potential value of the species.

Historically, plants and animals were classified into the following conservation categories:

1. Extinct (EX): Species no longer existing in the wild, surviving only under captivity or cultivation (e.g., cheetah, lesser Indian rhinoceros).
2. Endangered (EN): Species with critically few individuals because natural regeneration cannot keep pace with environmental or human-driven destruction. Without intervention, they will soon become extinct (e.g., Indian rhinoceros, Asiatic lion).
3. Vulnerable (VU): Species with decreasing populations that are likely to become endangered in the near future if unfavourable conditions continue.
4. Rare (R): Species with small global populations that are localised in restricted pockets or thinly scattered. Rarity depends on geographic range, habitat specificity, and local population size. It is often caused by narrow habitat needs, endemism, poor dispersal ability, or human activities.
5. Threatened (T): Species known to belong to the endangered, vulnerable, or rare categories, but lacking sufficient data to pinpoint exactly which one.
6. Intermediate (I): Species suspected to be endangered, vulnerable, or rare, but lacking present information to confirm.
7. Out of danger (O): Formerly threatened species that are now considered secure due to effective conservation measures or the removal of previous threats.

A more rigorous quantitative system was introduced to assess extinction risk, utilising five specific criteria:

1. Rate of population decline.
2. Geographic range.
3. Pre-existing small population size.
4. Highly restricted living area.
5. Quantitative analysis indicating a high probability of extinction in the wild.

Based on these criteria, species are placed into the following modern categories:

• The World Conservation Union (IUCN) evaluates and categorises species at risk of extinction based on their population decline, habitat quality, and geographical distribution.
• Historically, species were classified into seven broad conservation categories: extinct, endangered, vulnerable, rare, threatened, intermediate, and out of danger.
• The modern IUCN framework evaluates extinction risk using precise quantitative criteria, such as the rate of population decline, population size, and the extent of the geographic range.
• Under the updated system, species are placed into specific risk levels, ranging from Extinct (EX) and Critically Endangered (CR) to Least Concern (LC).
• 'Endangered' species face rapid population decline and immediate survival threats, whereas 'rare' species naturally possess small populations localised in restricted geographical pockets.
• Notable examples of endangered species in India include the Asiatic lion, Indian Rhinoceros, Hornbill, and the medicinal plant Rauwolfia serpentina.
• The Great Indian Bustard is a prime example of a highly endangered species; heavy hunting for its flesh has drastically reduced the population of this large ground bird.