The book The Sixth Extinction: An Unnatural History by Elizabeth Kolbert reviews the five previous mass extinction events on Earth and warns that we are currently faced with another, this time driven largely by man-made causes. Providing members of the public, conservation organizations, and government officials with reliable information and generating awareness about those species in danger of potential extinction is one step in countering this problem. The IUCN Red List serves in this important role, by providing high-quality scientific data in a broadly accessible and easily understandable manner. 

Officially known as the International Union for Conservation of Nature’s Red List of Threatened Species, the current IUCN Red List program grew out of the loose-leaf Red Data Books first published in the 1960’s. The list is maintained by the IUCN Species Survival Commission, a science-based network of volunteer experts, in partnership with other respected biodiversity and conservation-related organizations around the world. 

The types of species covered by the IUCN Red List include birds, mammals, fishes, reptiles and amphibians, plants, mollusks, corals, and more. Unlike some wildlife-related sites, the list also covers far more than a few charismatic species, with over 150,000 species included at the present time.  

Each species is assigned to one of seven threat categories including, in order of increasing severity, least concern, near threatened, vulnerable, endangered, critically endangered, extinct in the wild, and extinct. Each status is determined by a set of criteria, reflecting factors such as the number of individuals, distribution, habitat size and quality, and population trends over time. The assessment process is outlined on the web site. 

In addition to its threat assessment, information for each species is supplied on topics such as taxonomy, geographic range, population, habitat and ecology, threats, use and trade, and conservation actions. Data is given in summary form, with the option for users to click to see more detailed analysis of each element.  A bibliography of references is also provided and most entries include a photograph. In 2023 a data repository was also added. These features help make the site accessible to a wide-range of users, from those seeking just a quick fact or two to those looking for more in-depth materials.   

The IUCN Red List of Threatened Species has stood the test of time, providing data on threatened species for over 50 years. The need for this valuable information resource is only likely to increase as climate change, habitat destruction, and other factors put more species at risk around the world. 

Edward Lener, Director of Collections and Technical Services, University Libraries, Virginia Polytechnic Institute and State University

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