A survey of the world's largest free roaming giant tortoise population counted roughly 180,000 Aldabra giant tortoises on Aldabra Atoll.
By the numbers: The study put the best estimate at almost 183,000 adult and sub-adult tortoises and found the population relatively stable, the highest figure ever recorded for the species.
Zoom in: The survey was led by the Seychelles Islands Foundation and the University of Exeter, drawing on five years of tortoise counts between 2018 and 2022, and was published in the journal Ecology and Evolution.
- It is the first update since a widely cited figure of 100,000 tortoises from the late 1990s.
The backstory: Exploitation in the 19th century left fewer than 1,000 Aldabra tortoises on the island. A recovery effort led to the atoll becoming a strict nature reserve in 1981 and a Unesco site in 1982.
- "More than 180,000 giant tortoises roaming freely on our atoll is proof of what long-term commitment to conservation can achieve," said Dr Frauke Fleischer-Dogley, chief executive of the Seychelles Islands Foundation.
Between the lines: Counting them is harder than it sounds. "By modelling what we didn't see, as well as what we did, we've produced the most reliable baseline yet for this iconic Seychelles species," said co-author Dr Nancy Bunbury, noting the atoll's dense vegetation.
Yes, but: The authors say vigilance remains essential, with longer and more frequent droughts predicted to cut the shade and food available, and rising seas threatening low lying parts of the atoll.
What's next: Feral cats and black rats still prey on eggs and hatchlings, and the authors say a planned eradication of those invasive mammals could lift the last barrier to further growth.
Why it matters: Aldabra is one of only two places on earth where giant tortoises live in the wild, the other being the Galapagos, and a population this size is a rare measurable win for long running conservation work.
