NASA Is Helping Bring Giant Tortoises Back to the Galápagos

For the first time in more than 150 years, giant tortoises are returning to the wild on Floreana Island in the Galapagos, guided by NASA satellite data that is helping scientists discover where the animals can find food, water and nesting habitat.

This effort, a collaboration between Galápagos National Park management and the Galápagos Conservancy, marks a key milestone in restoring turtle populations in one of the most ecologically distinctive archipelagos on the planet.

On Floreana Island, turtles became extinct in the mid-1800s after intensive hunting by whalers and the introduction of new predators like pigs and rats, which consumed turtle eggs and hatchlings. Without the turtles, the island began to change. In the Galapagos, giant tortoises have historically helped shape the landscape by grazing on vegetation, opening passages through dense vegetation, and carrying seeds across the islands.

“This is exactly the kind of project where NASA’s Earth observations make a difference,” said Keith Gaddis, NASA Earth Action’s biological diversity and ecological forecasting program manager at NASA Headquarters in Washington. “We’re helping our partners answer a practical question: Where will these animals have the best chance of surviving – not just today, but decades from now?

On February 20, Galapagos National Park management and its conservation partners released 158 giant tortoises at two sites in Floreana.

“It’s a huge deal to find these turtles on this island. Charles Darwin was one of the last people to see them there,” said James Gibbs, vice president of science and conservation at the Galápagos Conservatory and co-principal investigator of the project.

In 2000, scientists made an unexpected discovery. Gibbs and other researchers discovered unusual turtles on Wolf Volcano, north of Isabela Island, the highest peak in the Galapagos, that were unlike any other known living turtles. About a decade later, DNA extracted from the bones of extinct Floreana turtles – found in island caves and in museum collections – confirmed that the turtles carried Floreana ancestry, launching a breeding program that has since produced hundreds of descendants expected to return to the island. Researchers believe whalers likely moved turtles between islands more than a century earlier.

The Galapagos National Park Branch has bred and released more than 10,000 tortoises in the Galapagos over the past 60 years, one of the largest rewilding efforts ever attempted. But each island presents a different puzzle.

Some hills and small mountains in the Galapagos intercept clouds and stay cool and moist thanks to evergreen vegetation. Others are dry enough that green vegetation appears only briefly after rain. When these areas are on the same island, turtles move between them, with some animals traveling miles each year between seasonal feeding areas and nesting areas.

“It’s difficult for turtles because they are introduced from captivity into this environment,” Gibbs said. “They don’t know where the food is. They don’t know where the water is. They don’t know where to nest. If you can put them where the conditions are already good, you give them a much better chance.”

This is where NASA satellite data comes into play.

NASA’s Earth observations allow scientists to map environmental conditions across the islands and track changes in vegetation, humidity and temperature over time – clues to where turtles can find food and water.

Using these recordings, Gibbs and Giorgos Mountrakis, the project’s principal investigator, and their team built a decision tool that combines satellite measurements of habitat and climate conditions with millions of field observations of turtles across the archipelago to determine where and when to release the animals.

“Suitable habitat models and environmental mapping are essential tools,” said Christian Sevilla, director of ecosystems at the Galápagos National Park Directorate. “They allow us to integrate climate, topographic and plant data to make evidence-based decisions. We are moving from intuition to precision.”

The decision tool is based on several satellite missions from NASA and its partners. Landsat and European Sentinel satellites monitor the state of vegetation. The Global Precipitation Measurement mission provides rainfall data. The Terra satellite helps estimate ground surface temperature, and terrain data adds elevation and landscape features. In some cases, high-resolution commercial satellite imagery, acquired through NASA’s Commercial Smallsat data acquisition program, helps teams evaluate potential release sites before field investigations begin.

Through the relationships between turtles and the environment, the team can map habitat suitability today and predict how it will change in coming decades as environmental conditions change.

“The forecasting part is key,” said Mountrakis, of the College of Environmental and Forest Sciences at the State University of New York at Syracuse. “This is not a one-year project. We’re looking at where the turtles will be successful in 20 or 40 years.”

Since turtles can live more than a century, habitat conditions decades from now matter as much as conditions today.

The release of the turtles is part of the larger Floreana ecological restoration project, which aims to eliminate invasive species like rats and feral cats and ultimately bring back 12 native animal species to the island, with the turtles serving as a keystone for rebuilding the ecosystem.

The Galápagos Conservancy also uses NASA satellite data and the decision tool developed to help guide turtle releases on other Galapagos islands and plan future reintroductions to the archipelago.

If successful, Floreana Island could once again be home to a significant population of turtles, helping to restore the relationships between animals, plants and the landscape that have shaped the island for thousands of years.

“For those of us who live and work in the Galapagos, this [release] “This demonstrates that large-scale ecological restoration is possible and that with science and long-term commitment we can recover an essential part of the archipelago’s natural heritage.”