The IUCN red list: a tool for combating species extinctions

By Rhiannon Williams

The IUCN red list of threatened species, introduced in 1994, is an online resource listing species and including information on their distribution and conservation status. The list was developed under the International Union for the Conservation of Nature (IUCN), which is the world’s oldest and largest conservation network 1. Its central mission is the conservation of biodiversity. By collecting data and classifying the species into nine different categories, the function of the red list is to draw attention to species most at risk of extinction and promote their conservation.

Species are sorted based on the IUCN red list categories and criteria which take into account information on population size and trends, distribution, threats and conservation actions in place 2. Species are allocated to the following groups: extinct (EX), extinct in the wild (EW), critically endangered (CR), endangered (EN), vulnerable (VU), near threatened (NT), least concern (LC), data deficient (DD) and not evaluated (NE). Species under the CR, EN and VU categories are all considered as “threatened” and are a conservation priority. The 2012 version of the red list categorised 19,817 species as threatened and 41% of these were amphibians 3. In this way, the red list highlights the species groups and individual species which need conserving the most.

Categories of the IUCN red list of threatened species

Categories of the IUCN red list of threatened species

The red list is not only the most comprehensive collection of data on the conservation status of species available; it also plays an increasing role in influencing the conservation activities of governments, non-governmental organisations (NGO’s) and scientific institutions. This information which would otherwise have been scattered and inaccessible is made available, and used to inform important decisions; for example identifying sites for conservation action 2.

We can describe the list as an indicator of trends in biodiversity. The Convention on Biological Diversity (CBD) was the first global treaty to tackle the issues of biodiversity loss, and their target for the year 2010 was “a significant reduction in the current rate of biodiversity loss”. This proved very difficult to measure, as neither past nor current rates of biodiversity loss were known; and the target itself was highly ambiguous. The red list is probably the best chance we have at present for estimating the current levels of biodiversity and trying to judge whether biodiversity levels increase or decrease in the future.

But the red list is not truly representative of the biodiversity on earth

A major problem with the list is that only a small proportion of the total plants and animals on earth have been assessed; the vast majority of species are not even classified or included on the list. Manyhave not been discovered yet, and in other cases there is simply not enough data available to be able to classify them. The red list is in fact not representative of the biodiversity on earth as it is biased towards well known species. This is because the biological knowledge collected by scientists on which the list is based is also biased. Certain areas of the world such as the Andes, Central and West Africa and Southeast Asia are underrepresented; and certain taxa such as plants and reptiles.

In some cases, the categorisation of species may be detrimental to their conservation status. Many newly described species such as Claire’s mouse lemur (Microcebus mamiratra) are listed as data deficient 4. Even though this species probably requires listing in one of the threatened categories, there is not sufficient data available to put it there. This poor categorisation may lead to the species being overlooked and the conservation of other less-threatened species being prioritized, or worse still, the habitat of the species being destroyed as it is not beleived to be endangered 5. The proportion of data deficient species varies among species groups; only 1% of birds are deficient compared to nearly half of all cartilaginous fishes (rays, sharks) 3.

So what, it’s not that big a deal

We must admit that a complete species list is far too ambitious a goal for the current scientific methods that are available. With the information and resources available to them, it is undeniable that the editors of the red list have done a good job.

African Elephant

African Elephant

The red list in action

Currently action is being taken by the IUCN and international governments to unite Asia and Africa in the joint goal of stopping the illegal trade of ivory 4. The African elephant is currently listed under the VU category and has a population of only 500,000. It is heavily poached in Africa and the ivory is traded to Asia. New regulations will include classifying wildlife trafficking as a “serious crime”, engaging communities living with elephants in their conservation and reducing the overall demand for illegal ivory.  For more information on the history of ivory trade watch this video from the national geographic website.

Other resources out there

The red list in not the only online resource with information on the conservation status of species. Bird life international is the world leader on bird conservation and has collected a wealth of knowledge about birds. Botanic Garden Conservation International is an international organisation dedicated to the conservation of threatened plants. BGCI has extensive online plant species lists. However; the compilation of information from all different species into one source is something quite unique to the red list.


[1] IUCN homepage. Retrieved 3rd December 2013, from

[2] Rogrigues et al. The value of the IUCN Red List for conservation. Trends in Ecology and Evolution 21, 71-76, (2006).

[3] IUCN red list of threatened species: strategic plan 2013-2020. (2013). Retrieved 3rd December 2013, from

 [4] IUCN red list of threatened species : Limitations of the data (2013). Retrieved 3rd December 2013, from

[5] Hoffmann & Brookes. Conservation planning and the IUCN Red List. Endangered Species Research 6, 113-125, (2008).

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.