On Instagram I often talk about ‘endangered species’ or ‘vulnerable species’, but what does this mean? And why do we put these labels on certain animals and plants? These categories are selected by the International Union for Conservation of Nature (IUCN). They use an internationally accepted standard of conservation categories for the status of rare and endangered species. I will go by all the 9 different categories, to explain what this means. There are 9 different categories;
The Red List criteria
The chart above shows the division of all the conservation categories. The species are place in a category using the IUCN Red List criteria. The Red List criteria are; A) Observable reduction in numbers of individuals. B) Total geographical area occupied by the species. C) Predicted decline in the number of individuals. D) Number of mating individuals currently alive. E) Probability the species will go extinct within a certain number of years or generations.
The first step is to decide if the species is evaluated or not evaluated. This is not as easy as it sounds. There currently are 390.900 different plant species and about 1.5 million animal species. Scientist predict that the number of animal species could be between 5 and 10 million! You can imagen, it is impossible to evaluate all these animal and plant species. Currently, the IUCN database contains 110.000 evaluated species. 31% of these are invertebrates, making this the most evaluated group. That means that millions of species are not evaluated (NO).
There are many species that they tried to evaluate, but that there was not enough data about the distribution and/or population status available to finish the evaluation. This might be the case for very rare animals or for the less popular species. There are fewer people studying the isopods than that there are people studying African rhino’s. The animals that do not have sufficient data to finish the evaluation get the label data deficient (DD).
When the plant or animal species are evaluated, they are in the 8 remaining categories. Bundled in; lower risk, threatened and extinct. We will start at the lowest level and work our way up to extinction. In the categorie least concern (LC) you can find species that are widespread and abundant. One step higher, the near-threatened (NT) species, these species do not meet the requirements to fall in one of the threatened categories now but is close to qualifying or is likely to do so in the near future.
The threatened subgroup is divided into three different categories; vulnerable, endangered and critical endangered.
The lowest out of three is the category vulnerable and states that evidence indicated that the species is facing a high risk of extinction in the wild. The species has to meet the following requirements; an observed or suspected population size reduction of 50% or more in the last 10 years or in three generations. And reduced biographical range smaller than 20.000 km2. The population has fewer than 10.000 mature individuals. Probability of extinction in the coming 100 years is at least 10%. IUCN currently lists 6362 animal species, 7430 plant species and 105 fungi species as Vulnerable (VU).
The endangered category indicated that the species is facing a very high risk of extinction in the wild. The species has to meet the following requirements; an observed or suspected population size reduction of 70% or more in the last 10 years or in three generations. And reduced biographical range smaller than 5.000 km2. The population has fewer than 250 mature individuals. Probability of extinction in the coming 100 years is at least 20%. Currently, there are 5108 animal species, 6557 plant species and 66 fungi species listed as endangered (EN).
The critically endangered category indicated that the species is facing an extremely high risk of extinction in the wild. The species has to meet the following requirements; an observed or suspected population size reduction of 90% or more in the last 10 years or in three generations. And reduced biographical range smaller than 100 km2. The population has fewer than 50 mature individuals. Probability of extinction in the coming 100 years is at least 50%. IUCN currently lists 3265 animal species, 3520 plant species and 22 fungi species as critically endangered (CR).
For the group extinction, there are two possibilities, extinct in the wild or completely extinct. For the first one, extinct in the wild, it means that the species only exist in cultivation, in captivity or as a naturalized population well outside its original range. Currently, there are 38 animals species and 39 plants species listed in the category extinct in the wild (EW).
A species is extinct when there is no reasonable doubt that the last species has died. A species is extinct when complete research has failed to record an individual. This research will be done in known and expected habitat. And at appropriate times, such as night time, different season and different years. All throughout its historical range. IUCN currently lists 762 animal species and 120 plant species as extinct (EX).