How is an endangered species different from a critically endangered species?

The International Union for Conservation of Nature (IUCN) classifies species based on their risk of extinction using the IUCN Red List of Threatened Species. While both categories fall under the broader umbrella of "threatened," they represent different levels of severity.1

Key Differences

• Critically Endangered (CR): This is the most serious designation for an imperiled organism, representing an extremely high risk of extinction in the wild. Criteria include a population decline of 80 to more than 90 percent over 10 years (or three generations) or a population size of fewer than 50 mature individuals.21
• Endangered (EN): This category indicates a very high risk of extinction. Criteria include a population decline of 50 to more than 70 percent over 10 years (or three generations) or a population size of fewer than 250 mature individuals.1

In essence, a critically endangered species is closer to extinction than an endangered species, reflecting a more rapid decline or a smaller remaining population. Both classifications are vital for prioritizing conservation efforts to reverse human-driven impacts like habitat loss and overexploitation.123