Once near extinction, 180,000 giant Tortoises now roam Seychelles Island

The population of Aldabra giant tortoises, once pushed to the brink of extinction, has rebounded to an estimated 180,000 on a remote island in Seychelles, far exceeding the country’s human population of around 122,000, according to reports by CNN and The Guardian.

A survey led by the Seychelles Islands Foundation (SIF) and the University of Exeter in the United Kingdom found that the population on Aldabra Atoll is the largest ever recorded for the species. The findings were published in the scientific journal Ecology and Evolution.

The estimate is based on five years of tortoise counts conducted between 2018 and 2022. It is the first major update since a widely cited estimate of 100,000 tortoises in the late 1990s. Researchers put the best estimate for adult and sub-adult tortoises at nearly 183,000.

The recovery marks a remarkable turnaround for the species. Heavy exploitation during the 19th century reduced the population on Aldabra to fewer than 1,000, bringing the tortoises close to extinction.

Conservation efforts subsequently helped secure the atoll’s status as a strict nature reserve in 1981. It was designated a UNESCO World Heritage Site in 1982, providing greater protection for its unique ecosystem.

“More than 180,000 giant tortoises roaming freely on our atoll is proof of what long-term commitment to conservation can achieve,” Frauke Fleischer-Dogley, chief executive of SIF, said.

Aldabra Atoll is one of only two places in the world where giant tortoises occur in the wild, with the other major population found in Ecuador’s Galápagos Islands.

However, scientists have warned that the recovery does not mean the species is free from threats. Longer and more frequent droughts driven by climate change could reduce the food and shade available to the tortoises, while rising sea levels threaten the atoll’s low-lying habitat.

Invasive species, including feral cats and black rats, also pose risks by preying on tortoise eggs and hatchlings. Researchers say removing these invasive mammals could further strengthen the population’s long-term survival prospects.

Nancy Bunbury, one of the study’s co-authors, said Aldabra’s dense vegetation makes accurate counts challenging. By accounting for tortoises that researchers could not directly observe, the team produced what it considers the most reliable population baseline to date.

The researchers hope the findings will help conservation managers monitor future changes and respond early to emerging threats.

Despite the record numbers, scientists stress that continued monitoring and conservation efforts will be essential to protect the giant tortoises from climate change, drought and invasive species.