The International Union for the Conservation of Nature (IUCN) maintains a ‘Red List’ of the world’s species and species can be listed no matter how abundant they are.
The IUCN is possibly the most well-known organisation and is widely used and accepted throughout scientific literature.
There are seven categories that range from:
Not Evaluated – The species has not yet been assessed
Data Deficient – There is not enough known to make an accurate evaluation
Least Concern – Species are widespread and abundant
Near Threatened – It is likely they will become endangered in the near future
Vulnerable – These species are at high risk of becoming endangered
Endangered – High risk of extinction in the wild
Critically Endangered – Very high risk of extinction in the wild
Extinct in the Wild – There are individuals surviving, but only in captivity
Extinct – There are no known individuals remaining on Earth following exhaustive and extensive surveys
The criterion for classification depends on a number of factors such as: the rate of decline, population size, geographic range, and the extent of fragmentation.
Once a species has been surveyed, they will be assigned one of these classifications along with a detailed report which can be viewed by anyone on the website here.
Endangered species face a ‘very high risk of extinction in the near future’. This taking into account the number of animals left, as well as their rate of decline and geographical distribution.
The IUCN currently have a huge target of trying to assess 150,000 species worldwide by 2020, and at they moment they’re on around 76,000. So there is still a long way to go. Assessing the world’s species is a huge task. Luckily there are dedicated groups to ensure the job is done. For example, the IUCN has been working with BirdLife International, who have assessed all the world’s 10,000 bird species, repeatedly, six times now, so every four years, they reassess all the world’s bird species.
Craig Hilton Taylor from the IUCN Red List told us “Lots of creatures are considered Least Concern but they still go on the Red List. That’s often a mistake people make, they think ‘oh it’s on the red list therefore it’s threatened’, no, most of the species on the red list are least concern, but we are trying to focus people’s attention on the endangered and critically endangered species.”