Scientists studying the Aldabra giant tortoise, native to the Seychelles in the Indian Ocean, have found that the species outnumbers the country’s human population.
The researchers, including scientists from Britain’s University of Exeter, published their findings in the journal Ecology and Evolution last month.
Their survey, conducted between 2018 and 2021, found that almost 183,000 tortoises lived on the Aldabra atoll compared with 100,000 in the late 1990s, the school said in a release Wednesday.
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The human population of the Seychelles was 102,612, according to the country’s 2022 census.
The study authors said that despite the drastic change in the numbers, they don’t believe the tortoise population nearly doubled between surveys. They said earlier surveys, which did not use modern techniques, probably missed tortoises and undercounted the population, the University of Exeter said.
“Aldabra’s giant tortoise monitoring programme is one of the longest running in the region, but the atoll’s dense vegetation makes counting tortoises genuinely difficult in places. 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,” Nancy Bunbury, one of the authors, said in the school’s release.
On a larger time scale, the population has seen massive growth. Exploitation of the atoll in the 1800s saw the tortoise population dwindle to as low as 1,000. The island then became a nature reserve in 1981, allowing for a more robust recovery by the species, according to The Guardian.
Aldabra is one of two locations hosting giant tortoise populations, though the atoll’s population is much smaller than the population of Galapagos tortoises on the island chain off the Pacific coast of South America, per the school’s release.

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