If so many species are going extinct, why don’t we hear about new extinctions every day?
The answer to that question is more complex than you might think. Once in a while, the last known individual of a species dies while on display in a zoo or other institution—for example, Martha the passenger pigeon or Toughie the last Rabbs’ tree frog. But in the vast majority of cases, the existence of the final representative of a species—the “endling”—is unknown.
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Take, for example, a Hawaiian bird known as the poʻouli (Melamprosops phaeosoma). The IUCN lists the species as “critically endangered (possibly extinct).” The bird hasn’t been seen in the wild since 2004, but it still hasn’t been moved into the “extinct” category. Right now there are 68 other species in that “possibly extinct” category. Hundreds more are still listed as “critically endangered.”
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[There] is another reason why some species haven’t been declared extinct yet—they’re alive, but unlikely to persist. The most notable example is the northern white rhino, which has just two females left in the world. The species still exists, but for all intents and purposes, it’s a walking case of extinction.
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