<p>This critically endangered South China tiger lives at the Suzhou Zoo in China. This is a species that may be gone from the wild now. As of 2015 there were only 100 in captivity.</p>

This critically endangered South China tiger lives at the Suzhou Zoo in China. This is a species that may be gone from the wild now. As of 2015 there were only 100 in captivity.

Photograph by Joel Sartore, National Geographic Photo Ark

Endangered species, explained

An animal is endangered when its numbers in the wild have dropped so low that it’s at great risk of extinction.

Whether a species is endangered—meaning at risk of extinction—depends on which definition you use. The International Union for Conservation of Nature’s Red List of Threatened Species classifies an animal as endangered when its numbers in the wild have dropped so low that it’s at “extremely high risk” of extinction.

Meanwhile, the United States’s Endangered Species Act of 1973 takes into consideration any destruction to a species’ habitat, whether it has been over-consumed, any disease or predation that threaten it, whether any other man-made factors put it in danger, and what policies currently exist to protect it.

When members of the public or a state agency propose to the U.S. Fish & Wildlife Service or the National Marine Fisheries Service that

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