A Galápagos tortoise thought to be extinct is now on the loose

180 years after its disappearance, a turtle returns to its home in the Galapagos

The release of 158 specially bred Floreana giant tortoises is a victory for both the animal and its long-lost island ecosystem.

By Rachel Newer edited by Andrea Thompson

The Galapagos Islands are renowned for their biodiversity, particularly their giant tortoises. But about 180 years ago, Floreana Island lost its only turtle, the Floreana giant tortoise (Chelonoidis niger niger), a subspecies of the giant Galapagos tortoise. Victim of the arrival of sailors, pirates and numerous invasive species, it was thought to have disappeared.

In 2000, however, scientists made a shocking discovery: A population of turtles 70 miles away on Isabela Island looked strikingly similar to the giant Floreana tortoise with its telltale saddle-shaped shell. Genetic testing confirmed that they were hybrid turtles descended from Floreana giant tortoises that must have accidentally ended up on the island after being taken aboard a ship to feed.

Today, for the first time in almost 200 years, turtles of Floreana ancestry returned to Floreana Island, following last week’s release of 158 individuals bred in a special captive breeding program.

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“Watching the turtles come up to Floreana and start exploring was incredibly moving,” says James Gibbs, vice president of science and conservation at the nonprofit Galápagos Conservancy. “It felt like the end of a 26-year effort but at the same time, a beginning.”

As part of the carefully managed breeding program, Gibbs and his colleagues matched adults collected from Isabela Island based on genetic testing to maximize the Floreana ancestry of their offspring. Although the resulting animals are not exact genetic replicas of their ancestors, they carry much of Floreana’s original lineage, Gibbs says.

Besides being a victory for the animals themselves, the turtle’s return will also be a boon for the island, Gibbs says. The Galapagos tortoise is what is known as a keystone species, dispersing seeds and helping to regenerate forests. It is therefore hoped that its return will begin to bring the island closer to its original ecological state.

“Anytime you can bring an ‘ecosystem engineer’ like giant tortoises back to an environment where they once roamed, we expect good things to happen,” said Rick Hudson, president emeritus of the nonprofit Turtle Survival Alliance, who was not involved in the research. After the return of Aldabra tortoises to Mauritius, for example, native plants returned and introduced vegetation declined. “Over time, the habitat begins to resemble its previous state,” says Hudson. “We expect similar results on Floreana.”

“The island’s ecosystems and evolutionary lineage are restarting, and the biological processes that shaped Floreana are returning,” says Gibbs. “It’s a powerful reminder that sometimes what seems lost forever is just waiting for the opportunity to return.”