Q. What is the world’s rarest animal?
A. Interestingly, the answer to this question changes every year, possibly every day. Of all the species that have gone extinct naturally through the ages, a point was reached when only one or two were left. Then there were none. Millions of insects have gone extinct naturally over the last millennium. And for at least a moment, each was the rarest animal on earth.
Another aspect to consider is the definition of “rare.” Tiger salamanders, which 99.44 percent of the people in the southeastern United States have never seen, are not rare in the sense of being scarce. Amphibian biologists know that tiger salamanders spend most of their lives in woods or open fields, living underground most of the year. In the Southeast, they come onto the surface when they breed in the winter, almost always moving overland at night when it is raining. Most people would regard tiger salamanders as a rare native species because they have never observed them in their natural habitat.
A more common perception of what makes something rare is that not many of them are known to exist. Simple math. Many species reaching “rarest species on earth” status are animals that are large, charismatic or have some notoriety due to publicity.
One example is the last passenger pigeon, named Martha, that died in the Cincinnati Zoo on Sept. 1, 1914. Martha was so famous by that point that the carcass was frozen and sent to the Smithsonian to be stuffed and displayed in future exhibits. The death of the presumed last Carolina parakeet in the same cage on Feb. 21, 1918, was the end of another indisputably rare species.
When species are considered to be down to their last few living individuals, questions often arise about whether a few might still be alive in the wild somewhere. Some ornithologists still hold to the hope that ivory-billed woodpeckers persist in an Arkansas swamp or a forest in Cuba. The extinction of the Tasmanian tiger was not accepted for decades after the last one was presumed killed. Some Australians probably think a few still exist.
Among large animals, one of the rarest turtles in the world is indisputably the Yangtze softshell turtle. Females, which get larger than the males, are said to reach lengths of more than 4 feet and are estimated to weigh more than 400 pounds. In October 2020, only one male and one female of these giant freshwater turtles were known to be alive. A third had died a few months earlier following attempts to breed a pair in captivity. So far no fertile eggs have survived. Habitat destruction, pollution and removal from the wild by fishermen have all contributed to the species’ decline.
Another turtle also achieved recognition as one of the rarest species on Earth. A male tortoise named Lonesome George lived on Pinta Island in the Galapagos, achieving international significance as a symbol for turtle conservation as the only remaining member of its species. Although other species of the giant tortoises still survive on some of the Galapagos Islands, upon Lonesome George’s death in 2012, that species became officially extinct.
Rarity, even extinction, is a natural biological phenomenon. What is not natural is when we (human beings) are responsible for the rarity of a species because of our assaults on them directly or on their environment. Perhaps we have reached a turning point in our stewardship of Earth. If, as I believe, most people value Earth’s biodiversity, then maybe we are ready to recognize the right of other species to inhabit this planet and to set ourselves a goal for the third decade of this millennium: Let us strive to ensure that being a victim of habitat destruction, pollution or unsustainable removal from the wild itself becomes a rarity.