A survey of Seychelles’ Aldabra Atoll estimates that nearly 183,000 adult and sub-adult giant tortoises live there, a figure researchers describe as the highest recorded for the species. The estimate is based on counts collected between 2018 and 2022, so it does not establish whether the population is increasing today.
The University of Exeter and Seychelles Islands Foundation team used statistical modeling to analyze the counts gathered by foundation staff. The study, published in Ecology and Evolution on October 4, 2026, provides what the university described as the first rigorous estimate covering the entire atoll.
A new estimate for Aldabra
The result updates a widely cited estimate of 100,000 tortoises that dated from the late 1990s. The study’s best estimate is almost 183,000 adult and sub-adult animals. Rounded to about 180,000, it is the figure used in public accounts of the research.
The Guardian reported that the population was relatively stable during the survey period. That finding applies to the years covered by the data, not necessarily to conditions after 2022. The researchers’ estimate is a new population baseline, rather than evidence of a recent surge.
The study’s title describes its approach as “semi-structured distance sampling.” The team applied statistical modeling to the tortoise counts collected by Seychelles Islands Foundation staff over five years. The supplied study announcement does not provide further detail about the modeling or explain how uncertainty around the estimate was quantified.
Conservation history and future pressures
Aldabra was made a strict nature reserve in 1981 and designated a UNESCO site in 1982, according to the University of Exeter announcement. It says tortoise numbers had fallen to fewer than 1,000 in the 19th century, placing the new estimate in the context of a long period of protection and recovery.
A researcher affiliated with the study characterized the estimate as a baseline and pointed to climate change, drought and invasive species as pressures facing the tortoises. Those concerns are forward-looking context in the announcement. The survey itself, as described in the supplied material, does not measure how those pressures have changed the population.
The reported total is therefore significant as a broad, updated count of Aldabra’s tortoises, while its time frame matters: the underlying observations end in 2022. The available research does not offer a new count for 2026 or establish a continuing upward trend.