EDITOR’S NOTE:  Call to Earth is a CNN editorial series committed to reporting on the environmental challenges facing our planet, together with the solutions. Rolex’s Perpetual Planet Initiative has partnered with CNN to drive awareness and education around key sustainability issues and to inspire positive action.

The story of the giant tortoises of the Galapagos is a story of pirates. Starting in the 16th century, these sailors began arriving at the islands, followed later by whalers, together sealing the destiny of the hundreds of thousands of specimens that inhabited the archipelago.

The resilience of the giant tortoises, which, according to experts, arrived in the Galapagos from South America 2 to 3 million years ago, became their greatest disadvantage: since they could survive for up to a year without food or water, they were captured by sailors, knowing they would endure in the holds of their ships. “And when these people wanted to eat, the tortoises were simply there, ready to go, and they had fresh meat,” Jorge Carrión, conservation director at the Galapagos Conservancy, an organization that has been working to preserve the archipelago since 1985, told CNN.

In just two centuries, between 100,000 and 200,000 tortoises disappeared from those almost mythical islands that Charles Darwin visited in 1835 aboard the HMS Beagle on a voyage that would become key to his theory of evolution.

The giant tortoises of the Galápagos are not a single species; each island has its own species of tortoise that, over time, adapted to its environment. Several of these became completely extinct because whalers stopping in the archipelago caught them for food and introduced other threats, such as invasive species.

The first to go extinct, around 1850, was the Floreana tortoise, named after the island where it lived. “They were very unusual tortoises, with a really pronounced shape — what we call a ‘saddle’ shape — that isn’t found anywhere else on the planet,” said James Gibbs, vice president of Science and Conservation at the Galapagos Conservancy and a professor at the State University of New York.

During a 2000 expedition to Wolf Volcano, the highest point in the Galápagos Islands, located on the northern tip of Isabela Island, researchers led by Gibbs found tortoises with a shell shape unusual for the area.

“There were thousands of native species there … but it quickly became clear that there were also some strange tortoises,” recalled Gibbs, whose connection to the Galápagos Islands goes back decades: he arrived as a volunteer when he was just a university student, and the islands, he says, transformed him, leading him to dedicate his life to their conservation.

On subsequent expeditions, they again encountered many of these “highly sculpted, saddle-shaped” tortoises living together in narrow canyons. “We called them aliens because we didn’t know what they were,” he remembers. They took blood samples and sent them to geneticists at Yale University, who confirmed that there were differences compared to the known species on that island and used the same term: aliens. Four years later, further genetic studies confirmed that they were from the Floreana lineage.

A long-lost giant returns to a Galápagos Island

A long-lost giant returns to a Galápagos Island

4:00

But how was it possible that they had become extinct on one island and reappeared 150 years later on a volcano at the other end of the archipelago? There are two hypotheses, said Carrión. One is a natural process: when there is heavy rain, flash floods sweep away everything in their path, which could have transported the tortoises between islands. But scientists believe that humans were most likely responsible.

“Remember that pirates and whalers used to come to the Galápagos and take dozens or hundreds of tortoises on their ships. One possibility is that an accident occurred near Wolf Volcano,” he explains. The other is purely logistical: Isabela Island, due to its location, was the last checkpoint for ships before they ventured into the Pacific. There, they checked the weight of the tortoises and if the ship was over its weight limit, they would discard some, which, fortunately for the future, may have ended up on an unexpected island.

The Fausto Llerena Land Tortoise Breeding Center has been working since 1965 to protect these giant reptiles. They have already successfully bred, raised, and released species from the islands of Española and Santa Fe, among others. Nineteen specimens of the Floreana lineage were transferred there after their discovery on Wolf Volcano, for care and reproduction.

Freddy Villalba, from the Galapagos National Park Directorate, has been a park ranger for 23 years and manages this breeding center.

They work with adult tortoises and eggs laid in captivity, as in the case of those from Floreana, or collected from the wild. They mark, weigh, and place the eggs in incubators at different temperatures. At this stage, the turtles’ sex is still undetermined: it will be determined by the temperature at which the eggs develop, said Villalba. In incubators programmed to 29.5°C (85.1 degrees Fahrenheit), female turtles will develop, and in those at 28°C (82.4 degrees Fahrenheit), it will be males.

After four months of incubation, the eggs hatch and the staff transfers the newborn turtles to dark, humidity-controlled boxes where they will remain for a month, feeding exclusively on their yolk sac, replicating the process they would undergo in the wild.

Thirty days later, they emerge into enclosures where they feed on chopped leaves called “elephant ears,” their diet for the first two years. During this initial stage, they must be “very carefully protected,” said Villalba, because they measure 8 to 9 centimeters and are easy prey for predators.

NASA technology and satellite tracking

In February 2026, 158 baby tortoises were released on Floreana Island with satellite tracking devices so scientists could study how they respond to their habitat, and how the habitat responds to them. With resources from NASA, specialists identified the best areas for their release, where they could later nest.

These are descendants of the tortoises found more than 20 years ago on the volcano, which have “thrived tremendously,” said Gibbs. “You never know how animals brought from the wild will adapt to captivity, but these have thrived remarkably. They are voracious eaters and highly reproductive; in a very short time, they have produced 800 baby tortoises and will continue to produce an average of 60 per year,” Gibbs added.

Walter Chimborazo, a field assistant with the Galapagos Conservancy at the breeding center, witnessed the birth of the tortoises that now roam Floreana Island. “They were so small, smaller than the palm of my hand,” he recalled.

Their release makes him happy, of course, but it also leaves him with the bittersweet feeling of goodbye. “I’ve spent more time here at work than at home … On one hand, I’m happy, but on the other hand, I’m sad because I’m really not going to see them again.”

His father worked at the same breeding center. Chimborazo knows his job is a privilege and is proud of having given his all: “I know I took care of them; I raised them. I taught them so they could survive on their island.”

The recently released tortoises are hybrids, explained Cristian Sevilla, director of Ecosystems at the Galapagos National Park. Their genetic makeup is partly that of the Floreana tortoises, which went extinct in the 19th century, and partly that of native species from the Wolf Volcano area.

“We haven’t yet found a pure Floreana tortoise, but we believe they exist. We found some young specimens on Wolf Volcano that are 50% Floreana and 50% a native species, which implies they necessarily had a purebred parent,” Gibbs explained. “Therefore, it’s likely that some are still roaming the vastness of this volcano; perhaps they are some of the original tortoises that whalers brought and left there.” Floreana tortoises can live for more than 100 years in the wild.

Carrión described the giant tortoises as “ecosystem engineers” of the archipelago. “They help disperse seeds. They help build and modify the plant communities of the Galápagos ecosystems and are therefore essential not only for themselves as tortoises, but also for the ecological dynamics of the ecosystems,” he explained.

The key lies in their diet: each giant tortoise eats up to 225 kilograms (496 pounds) of vegetation per year. “The process of digesting a single bite of plant material takes about a month,” said Gibbs, “so the remains aren’t expelled until after that time.” “By then, the animal has already migrated and traveled many kilometers, thus dispersing enormous quantities of seeds. And many plants, in fact, don’t germinate very well unless they’ve passed through the digestive tract of a giant tortoise.”

But also, weighing up to 400 kilograms (882 pounds), they’re like excavators, Gibbs explained: “They dig through the vegetation; they flatten it and prepare their beds for the night.”

“If they disperse seeds, they’re helping other species to feed on these plants. If they create spaces, these spaces are occupied by other species, such as land birds, for example,” Sevilla said.

By working on the recovery of the giant tortoises, the conservationists are restoring this unique ecosystem. Conservation efforts have also eradicated some of the invasive species that arrived with humans, such as goats, pigs, and donkeys, and are working to control two other major threats: rodents and cats.

The Galápagos Islands have some of the highest levels of endemism on the planet, meaning species that are found nowhere else. Around 80% of land birds, 97% of reptiles and land mammals, more than 30% of plants, and more than 20% of marine species there are endemic.

One of the characteristics that has made the Galápagos Islands a key reservoir of biodiversity is their remote location — in the Pacific Ocean, nearly 1,000 kilometers (621 miles) off the coast of Ecuador — which has allowed species to “evolve separately from the mainland,” said Carrión.

That doesn’t mean their lives are without challenges, he added: “Life here in the Galápagos is very beautiful, but it’s also very harsh for the species; they have to survive very severe conditions” such as aridity in some areas, water stress, salinity stress, and UV radiation stress.

The way Galápagos species interact with humans is also unusually friendly. “There’s a rule to maintain a distance of 2 meters (6.6 feet) from the wildlife, since the animals don’t perceive humans as a threat … You really manage to connect with and understand the animals,” said Gibbs.

Giant tortoises are a curiosity today, only living in the wild in the Galápagos Islands or the Aldabra Atoll in the Indian Ocean. They were the first megafauna species to spread across Asia, South America and North America. Until just 10,000 years ago, they even inhabited areas as far away as Florida.

The Galápagos Islands have been the site of extraordinary conservation work, a collaborative effort between the government, civil organizations and the local population. This work has allowed more than 9,000 giant tortoises to be bred in captivity and released into the wild over the past 60 years.

But full recovery takes time. The lesson of the tortoises is one of patience. “They grow slowly, yes, but they are very constant and persistent. It’s like the fable of the tortoise and the hare: in the end, the tortoise wins the race,” Gibbs reflected.

And at the same time, they are extraordinarily noble. As Gibbs put it, “They are such resilient, long-lived, and tenacious creatures that they have, in fact, allowed us to solve some of the problems we have created.”