Science glossary film: Endangered

An endangered species is one that is at risk of extinction. The precise definition varies, but is evaluated by monitoring changes in population size over time. The International Union for Conservation of Nature – or IUCN – produces a Red List of species under threat, including vulnerable, endangered and critically endangered categories.

The precise definition varies, but is evaluated by monitoring changes in population size over time. The International Union for Conservation of Nature – or IUCN – produces a Red List of species under threat, including vulnerable, endangered and critically endangered categories.