We’ve Rediscovered ‘Extinct’ Giant Tortoises

The Galápagos Islands, 1,000 kilometers off the coast of South America, are probably most famous as the place that inspired Charles Darwin’s theory of evolution. They are home to an extraordinary array of wildlife, including giant Galápagos tortoises, the world’s largest land-living cold-blooded animals.

The tortoises once thrived in the archipelago. There were originally 15 species that evolved as the islands formed volcanically. However, since the arrival of people four species have become extinct.

A few weeks ago we returned from an expedition to the islands in search of two of these extinct species of tortoises. It may sound like a fool’s errand, but our expedition was a success.

Here’s how we did it.

Tortoises under threat

The Galápagos Islands were colonised in the late 1800s. A combination of poaching by whalers and pirates, and introduced pests competing for food and eating eggs and hatchlings, led to tortoises being exterminated on some islands, and dramatically reduced on others.

Darwin wrote about the harvesting of the species of tortoise found only on Floreana Island (Chelonoidis elephantopus), which was exterminated within 15 years of his visit to the Galápagos in 1835.

The tortoise found only on Pinta Island (Chelonoidis abingdoni) went formally extinct in 2012, when its last representative, a male held in captivity and nicknamed Lonesome George, died. He was a major conservation icon and at one point considered by Guinness World Records as the world’s rarest living creature.

Finding extinct tortoises

Ten years ago our genetic research program made a very surprising discovery. Some tortoises on Volcano Wolf, on Isabela Island, didn’t match others normally found on the volcano (Chelonoidis becki). Instead, their DNA matched that of the extinct species from Floreana and Pinta.

These exciting discoveries led to an expedition on Volcano Wolf —> Read More