A landmark survey of the world’s largest free‑roaming giant tortoise population has revealed that the once endangered species is thriving. The study, conducted by the Seychelles Islands Foundation and the University of Exeter, found that approximately 180,000 Aldabra giant tortoises roam Aldabra Atoll, the highest figure ever recorded for the species and far exceeding the human population of Seychelles.
The most recent survey analysed five years of tortoise counts between 2018 and 2022. It is the first update since the widely cited figure of 100,000 tortoises from the late 1990s. The study, published in the journal Ecology and Evolution, estimates a best figure of almost 183,000 adult and sub‑adult tortoises, indicating a relatively stable population over the period.
In the 19th century, exploitation had reduced the number of Aldabra tortoises to fewer than 1,000. A recovery programme established the island as a strict nature reserve in 1981 and a UNESCO site in 1982, turning it into one of only two places in the world where giant tortoises live in the wild, the other being the Galápagos. Researchers describe the population growth as one of the greatest conservation success stories of the Indian Ocean.
Despite the encouraging numbers, the authors warn that vigilance remains essential. Climate change is expected to bring longer, more frequent droughts that could reduce shade and food, while rising sea levels threaten low‑lying parts of the atoll. Invasive mammals such as feral cats and black rats still prey on tortoise eggs and hatchlings. Planned eradication of these species could remove the last barriers to further growth and help the tortoises withstand future climate pressures. The study provides a reliable baseline that conservation managers can use to track changes and act early as new pressures arise.
