An endangered species is one at high risk of becoming extinct in the wild in the near future. The International Union for Conservation of Nature (IUCN) assesses species and publishes the Red List of Threatened Species.The IUCN categories, from lowest to highest risk, are:
• Least Concern
• Near Threatened
• Vulnerable
• Endangered
• Critically Endangered
• Extinct in the Wild (survives only in captivity or cultivation)
• Extinct
Species that are Vulnerable, Endangered or Critically Endangered are together described as threatened. Species with too little information to assess are classed as Data Deficient.A species is placed in a category using criteria such as:
• how fast its population is declining;
• how small its population is (the number of mature individuals);
• how small and fragmented its geographical range is;
• the probability of extinction estimated from population models.For example, a species whose population has fallen by 90% or more over ten years or three generations can be listed as Critically Endangered.Endangered species include the tiger, the African wild dog and the blue whale; the Sumatran orangutan and the black rhino are Critically Endangered.Small populations are especially at risk because they have low genetic diversity, so they are less able to adapt to change or resist disease, and a single event such as a fire, storm or epidemic could wipe them out. Listing a species helps set priorities for conservation and for trade controls.
• Least Concern
• Near Threatened
• Vulnerable
• Endangered
• Critically Endangered
• Extinct in the Wild (survives only in captivity or cultivation)
• Extinct
Species that are Vulnerable, Endangered or Critically Endangered are together described as threatened. Species with too little information to assess are classed as Data Deficient.A species is placed in a category using criteria such as:
• how fast its population is declining;
• how small its population is (the number of mature individuals);
• how small and fragmented its geographical range is;
• the probability of extinction estimated from population models.For example, a species whose population has fallen by 90% or more over ten years or three generations can be listed as Critically Endangered.Endangered species include the tiger, the African wild dog and the blue whale; the Sumatran orangutan and the black rhino are Critically Endangered.Small populations are especially at risk because they have low genetic diversity, so they are less able to adapt to change or resist disease, and a single event such as a fire, storm or epidemic could wipe them out. Listing a species helps set priorities for conservation and for trade controls.