On the remote Aldabra Atoll in the Seychelles, nearly 183,000 giant tortoises now roam terrain where fewer than a thousand survived two centuries of commercial exploitation — a recovery that stands as one of the Indian Ocean's most profound acts of collective patience. A five-year survey by the Seychelles Islands Foundation and the University of Exeter has confirmed the highest population ever recorded for the species, nearly doubling estimates that had gone unchallenged since the late 1990s. The achievement is a testament to what sustained legal protection and institutional commitment can acc
Seychelles giant tortoise population surges to 180,000 in conservation triumph
proof of what long-term commitment to conservation can achieve
Mark
So we went from fewer than a thousand tortoises to nearly 180,000. That's extraordinary. But I'm curious—how confident are researchers in that 180,000 figure?
Mimi
The survey team analyzed five years of field counts and used statistical modeling to account for tortoises they couldn't see directly in the dense vegetation. They're calling it the most reliable baseline ever produced for the species.
Luke
But it's still an estimate, right? They didn't count every tortoise individually. The previous figure of 100,000 stood for about 25 years—how much of this jump is real population growth versus better counting methods?
Mimi
That's a fair question. The study does suggest the population was relatively stable during the 2018-2022 period itself. The jump from 100,000 to 180,000 likely reflects both actual growth since the 1990s and improved methodology.
Mark
What made the recovery possible in the first place?
Mimi
Legal protection. The atoll became a strict nature reserve in 1981 and a UNESCO site in 1982. That created the conditions for uninterrupted recovery over four decades.
Luke
And now? What's actually threatening them going forward?
Mimi
Climate change is the big one—longer droughts, rising sea levels. But also invasive species. Feral cats and rats eat eggs and hatchlings. Researchers say removing those invasive mammals could unlock further population growth.
Mark
So this is a success story, but it's not finished.
Mimi
Exactly. The researchers are explicit about that. The numbers are a baseline for tracking future change, not proof the problem is solved.
Luke
And Aldabra is one of only two places where giant tortoises live wild—the other being the Galápagos, which has a much smaller population. So this one atoll matters enormously for the species.
Mimi
Right. If something goes wrong here, there's no backup.
Le Pouls
- A species that once teetered at fewer than 1,000 individuals has surged to nearly 183,000 — a reversal so dramatic it reframes what conservation can realistically accomplish.
- The previous estimate of 100,000, accepted for nearly three decades, has been almost doubled by researchers using sophisticated models designed to count tortoises hidden beneath Aldabra's dense vegetation.
- Despite the milestone, scientists are sounding a clear note of caution: feral cats and black rats continue to destroy eggs and hatchlings, quietly eroding the population's future from the ground up.
- Longer droughts and rising sea levels are projected to shrink both the shade and vegetation the tortoises depend on, threatening to undo in years what took decades to build.
- Researchers and conservationists are now pressing for the eradication of invasive mammals on the atoll — a targeted intervention they believe could unlock the next chapter of the species' recovery.
On the remote Aldabra Atoll in the Seychelles, nearly 183,000 giant tortoises now roam terrain where fewer than a thousand survived two centuries of commercial exploitation — a recovery that stands as one of the Indian Ocean's most profound acts of collective patience. A five-year survey by the Seychelles Islands Foundation and the University of Exeter has confirmed the highest population ever recorded for the species, nearly doubling estimates that had gone unchallenged since the late 1990s. The achievement is a testament to what sustained legal protection and institutional commitment can accomplish across generations, even as the horizon carries new warnings: climate change, rising seas, and invasive predators remind us that recovery is never a destination, only a direction.
On Aldabra Atoll, a remote speck of the Seychelles, nearly 180,000 giant tortoises now move through dense vegetation — outnumbering the entire human population of the nation. A new survey has confirmed what conservationists long hoped: the species has not merely survived, but flourished.
The count, produced by the Seychelles Islands Foundation and the University of Exeter from five years of field data collected between 2018 and 2022, places the adult and sub-adult population at approximately 183,000 — nearly double the estimate of 100,000 that had stood since the late 1990s. It is the highest figure ever recorded for the species, and a stunning reversal from the 19th century, when commercial exploitation reduced the population to fewer than 1,000 individuals.
The recovery was not accidental. Aldabra became a strict nature reserve in 1981 and received UNESCO World Heritage status the following year, creating the legal framework that allowed the tortoises to rebuild undisturbed for more than four decades. Because the atoll's thick vegetation makes direct counting nearly impossible, researchers developed models accounting for tortoises hidden from view — producing what one co-author called "the most reliable baseline yet" for tracking the population into the future.
But the researchers are careful to frame the news as a beginning rather than an ending. Droughts are predicted to intensify, rising sea levels threaten the atoll's low-lying terrain, and invasive feral cats and black rats continue to prey on eggs and hatchlings. Scientists stress that the new numbers offer a baseline, not a guarantee, and that the planned eradication of invasive mammals may be the most critical next step in ensuring that decades of hard-won recovery are not quietly reversed.
On Aldabra Atoll, a remote island in the Seychelles, nearly 180,000 giant tortoises move through the dense vegetation, outnumbering the human population of the entire nation. A new survey has confirmed what conservationists have long hoped: one of the world's most endangered species has not merely survived, but flourished.
The count, released by researchers from the Seychelles Islands Foundation and the University of Exeter, represents the most comprehensive assessment of the Aldabra giant tortoise population in decades. Between 2018 and 2022, the team analyzed five years of field data to arrive at a figure of approximately 183,000 adult and sub-adult tortoises—nearly double the widely accepted estimate of 100,000 that had stood since the late 1990s. The new baseline is the highest population figure ever recorded for the species and marks a dramatic reversal from the brink of extinction.
Two centuries ago, the story was catastrophically different. Commercial exploitation in the 19th century reduced the Aldabra population to fewer than 1,000 individuals. The species survived only because of deliberate, sustained intervention. In 1981, Aldabra Atoll became a strict nature reserve, and the following year it gained UNESCO World Heritage status. These designations created the legal and institutional framework that allowed the tortoise population to recover uninterrupted for more than four decades. Dr. Frauke Fleischer-Dogley, CEO of the Seychelles Islands Foundation, called the result "proof of what long-term commitment to conservation can achieve." The recovery has earned recognition as one of the Indian Ocean's greatest conservation achievements.
The survey itself required methodological sophistication. The atoll's thick vegetation makes direct counting nearly impossible in many areas. Researchers developed models that accounted not only for the tortoises they observed but also for those hidden from view, producing what Dr. Nancy Bunbury, a co-author of the study published in Ecology and Evolution, described as "the most reliable baseline yet." This baseline will serve as a benchmark for tracking the population across future decades.
Yet the researchers who conducted the survey are careful to frame the news as a beginning rather than an ending. Aldabra Atoll faces mounting pressures that could reverse the gains. The climate is shifting in ways that threaten the tortoises directly: longer and more frequent droughts are predicted to reduce both the shade and vegetation that sustain the population, while rising sea levels pose a risk to the atoll's low-lying areas. Invasive species—particularly feral cats and black rats—continue to prey on tortoise eggs and hatchlings, limiting recruitment to the population. Dr. Dave Hudson of the University of Exeter emphasized that the new numbers "provide a baseline—not an endpoint." The planned eradication of invasive mammals could remove one significant barrier to further growth and help the population withstand the climate pressures ahead. Without such action, and without continued vigilance, the recovery that took decades to achieve could face new threats in the decades to come.
Citations marquantes
More than 180,000 giant tortoises roaming freely on our atoll is proof of what long-term commitment to conservation can achieve.— Dr. Frauke Fleischer-Dogley, CEO of Seychelles Islands Foundation
The numbers provide a baseline—not an endpoint. Hopefully we have provided the conservation managers the evidence they need to track future change and act early as the tortoises face increasing pressures from climate change, drought and invasive species.— Dr. Dave Hudson, University of Exeter
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Climate & Environment