The IUCN Red List (introduced in 1994) of Threatened Species is widely recognized as the most comprehensive, objective global approach for evaluating the conservation status of plant and animal species. From its small beginning, The IUCN Red List has grown in size and complexity and now plays an increasingly prominent role in guiding conservation activities of governments, NGOs and scientific institutions.
IUCN has classified species into categories of Extinct, Extinct in wild, Critically Endangered, Endangered, Vulnerable, etc based on data collected across the world.
IUCN has a Red List which provides a systematic list of plants and animals into various categories.
Structure of Categories:
Definition of Categories:
1. Extinct (EX)
A taxon is Extinct when there is no reasonable doubt that the last individual has died.
2. Extinct in Wild (EW)
A taxon is Extinct in the Wild when it is known only to survive in cultivation, in captivity or as a naturalized population (or populations) well outside the past range.
3. Critically Endangered (CR)
A taxon is Critically Endangered when the best available evidence indicates that it meets any of the criteria A to E for Critically Endangered (see Section V), and it is therefore considered to be facing an extremely high risk of extinction in the wild.
Criteria for Critically Endangered:
A. Reduction in population size:
1. Reduction of population ≥ 90% over the last 10 years or three generations, whichever is the longer, where the causes of the reduction are clearly reversible AND understood AND ceased.
2. Reduction of population ≥ 80% over the last 10 years or three generations, whichever is the longer, where the reduction or its causes may not have ceased OR may not be understood OR may not be reversible.
B. Geographic range in the form of either B1 (extent of occurrence) OR B2 (area of occupancy):
B.1. Extent of occurrence estimated to be less than 100 km2, and estimates indicating severely fragmented or known to exist at only a single location.
B.2. Area of occupancy estimated to be less than 10 km2, and severely fragmented or known to exist at only a single location.
C. Population size estimated to number fewer than 250 mature individuals and an estimated continuing decline of at least 25% within three years or one generation, whichever is longer.
D. Population size estimated to number fewer than 50 mature individuals.
E. Quantitative analysis showing the probability of extinction in the wild is at least 50% within 10 years or three generations, whichever is the longer (up to a maximum of 100 years).
Endangered (EN)
A taxon is endangered when the best available evidence indicates that it meets any of the criteria A to E for Endangered, and it is therefore considered to be facing a very high risk of extinction in the wild.
Criteria for Endangered:
A. Reduction in population size based on any of the following:
1. Reduction in population ≥ 70% over the last 10 years or three generations, whichever is the longer, where the causes of the reduction are clearly reversible AND understood AND ceased.
2. An observed, estimated, inferred or suspected population size reduction of ≥ 50% over the last 10 years or three generations, whichever is the longer, where the reduction or its causes may not have ceased OR may not be understood OR may not be reversible.
B. Geographic range in the form of either B1 (extent of occurrence) OR B2 (area of occupancy) OR both:
B.1. Extent of occurrence estimated to be less than 5000 km2, and severely fragmented or known to exist at no more than five locations.
B.2. Area of occupancy estimated to be less than 500 km2, and severely fragmented or known to exist at no more than five locations.
C. Population size estimated to number fewer than 2500 mature individuals and an estimated continuing decline of at least 20% within five years or two generations, whichever is longer.
D. Population size estimated to number fewer than 250 mature individuals.
E. Quantitative analysis showing the probability of extinction in the wild is at least 20% within 20 years or five generations, whichever is the longer.
Vulnerable (VU)
A taxon is Vulnerable when the best available evidence indicates that it meets any of the criteria A to E for Vulnerable, and it is therefore considered to be facing a high risk of extinction in the wild.
Criteria for Vulnerable:
A. Reduction in population size based on any of the following:
1. Reduction in population ≥ 50% over the last 10 years or three generations, whichever is the longer, where the causes of the reduction are: clearly reversible AND understood AND ceased.
2. Reduction of population ≥ 30% over the last 10 years or three generations, whichever is the longer, where the reduction or its causes may not have ceased OR may not be understood OR may not be reversible.
B. Geographic range in the form of either B1 (extent of occurrence) OR B2 (area of occupancy) OR both:
B.1. Extent of occurrence estimated to be less than 20,000 km2, and severely fragmented or known to exist at no more than 10 locations.
B.2. Area of occupancy estimated to be less than 2000 km2, and estimates indicating severely fragmented or known to exist at no more than 10 locations.
C. Population size estimated to number fewer than 10,000 mature individuals and an estimated continuing decline of at least 10% within 10 years or three generations, whichever is longer.
D. Population size estimated to number fewer than 1000 mature individuals.
E. Quantitative analysis showing the probability of extinction in the wild is at least 10% within 100 years.
Near Threatned (NT)
A taxon is Near Threatened when it has been evaluated against the criteria but does not qualify for Critically Endangered, Endangered or Vulnerable now, but is close to qualifying for or is likely to qualify for a threatened category in the near future.
Least Concern (LC)
A taxon is Least Concern when it has been evaluated against the criteria and does not qualify for Critically Endangered, Endangered, Vulnerable or Near Threatened.
Data Deficient (DD)
A taxon is Data Deficient when there is inadequate information to make a direct, or indirect, assessment of its risk of extinction based on its distribution and/or population status.
Not Evaluated (NE)
A taxon is Not Evaluated when it is has not yet been evaluated against the criteria.
IUCN Categories, and Some Animals in those Categories, Include:
Extinct: Examples: Atlas bear, Aurochs, Bali Tiger, Blackfin Cisco, Caribbean Monk Seal, Carolina Parakeet, Caspian Tiger, Dinosaurs, Dodo, Dusky Seaside Sparrow, Elephant Bird, Golden Toad, Great Auk, Haast’s Eagle, Japanese Sea Lion, Javan Tiger, Labrador Duck, Moa, Passenger Pigeon, Pterosaurs, Saber-toothed cat, Schomburgk’s deer, Short-faced bear, Steller’s Sea Cow, Thylacine, Toolache Wallaby, Western Black Rhinoceros, Woolly Mammoth, Woolly Rhinoceros.
Extinct in the Wild: captive individuals survive, but there is no free-living, natural population. Examples: Barbary Lion (maybe extinct), Catarina Pupfish, Hawaiian Crow, Northern White Rhinoceros, Scimitar Oryx, Socorro Dove, Wyoming Toad
Critically Endangered: It faces an extremely high risk of extinction in the immediate future. Examples: Addax, African Wild Ass, Alabama Cavefish, Amur Leopard, Arakan Forest Turtle, Asiatic Cheetah, Axolotl, Bactrian Camel, Brazilian Merganser, Brown Spider Monkey, California Condor, Chinese Alligator, Chinese Giant Salamander, Gharial, Hawaiian Monk Seal, Iberian Lynx, Island Fox, Javan Rhino, Kakapo, Leatherback Sea Turtle, Mediterranean Monk Seal, Mexican Wolf, Mountain Gorilla, Philippine Eagle, Red Wolf, Saiga, Siamese Crocodile, Spix’s Macaw, Southern bluefin tuna, Sumatran Orangutan, Sumatran Rhinoceros, Vaquita, Yangtze River Dolphin
Endangered: It faces a very high risk of extinction in the near future. Examples: African Penguin, African Wild Dog, Asian Elephant, Asiatic Lion, Blue Whale, Bonobo, Bornean Orangutan, Chimpanzees, Dhole, Ethiopian Wolf, Hispid Hare, Giant Otter, Giant Panda, Goliath Frog, Gorillas, Green Sea Turtle, Grevy’s Zebra, Hyacinth Macaw, Japanese Crane, Lear’s Macaw, Malayan Tapir, Markhor, Persian Leopard, Proboscis Monkey, Pygmy Hippopotamus, Red-breasted Goose, Rothschild Giraffe, Snow Leopard, Steller’s Sea Lion, Scopas tang, Takhi, Tiger, Vietnamese Pheasant, Volcano Rabbit, Wild Water Buffalo
Vulnerable: It faces a high risk of extinction in the medium-term. Examples: African Elephant, American paddlefish, Clouded Leopard, Cheetah, Dugong, Far Eastern Curlew, Fossa, Galapagos Tortoise, Gaur, Blue-eyed cockatoo, Golden Hamster, Whale Shark, Crowned Crane, Hippopotamus, Humboldt Penguin, Indian Rhinoceros, Komodo Dragon, Lesser White-fronted Goose, Lion, Mandrill, Maned Sloth, Mountain Zebra, Polar Bear, Red Panda, Sloth Bear, Takin, Yak
Near Threatened: These species may be considered threatened in the near future. Examples: African Grey Parrot, American Bison, starry blenny, Asian Golden Cat, Blue-billed Duck, Emperor Goose, Emperor Penguin, Eurasian Curlew, Jaguar, Leopard, Magellanic Penguin, Maned Wolf, Narwhal, Okapi, Solitary Eagle, Southern White Rhinoceros, Striped Hyena, Tiger Shark, White Eared Pheasant.
Least Concern: There is no immediate threat to the survival of the species. Examples: American Alligator, American Crow, Indian Peafowl, Baboon, Bald Eagle, Brown Bear, Brown Rat, Brown-throated sloth, Canada Goose, Cane Toad, Common Wood Pigeon, Cougar, Common Frog, Orca, Giraffe, Grey Wolf, House Mouse,[5] Human, Palm cockatoo, cowfish, Mallard, Meerkat, Mute Swan, Platypus, Red-billed Quelea, Red-tailed Hawk, Rock Pigeon, Scarlet Macaw, Southern Elephant Seal, Milk shark, Red howler monkey.
