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.
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 a species be listed as endangered under the law, research and management plans are formed to help those species survive. It is illegal under the Endangered Species Act to capture, hunt, shoot, or otherwise harm an animal that’s listed as endangered.
Sometimes, federal agencies decide that although a species could be considered endangered, other species are higher priorities. In those cases, the animal or plant gets limited protections.
One animal whose numbers have increased through conservation is the bald eagle. There were only about 500 bald eagles in the continental United States in the 1960s because of pesticides that damaged the shells of their eggs. Conservation efforts including captive breeding programs, habitat protection, and a ban on the insecticide DDT helped the bald eagle’s numbers soar back into the thousands.
Another is the giant panda, which was declared no longer endangered in 2016 thanks to 50 years of efforts to save it.
U.S. Rep. John Dingell (D-Mich.), who wrote the Endangered Species Act, argued that “only natural extinction is part of natural order.” Scientists believe that 227 species—including the grizzly bear, the peregrine falcon and the gray wolf—were saved from extinction in the first 33 years of the law’s existence.
Still, critics argue that the act is expensive and ineffective because it protects so many species. Several federal courts have heard and rejected arguments that the Endangered Species Act is unconstitutional, and members of Congress have tried to weaken the law in small ways.
Luckily for endangered species, there are many people looking out for them. To learn what National Geographic is doing to help, visit nationalgeographic.org.