A comprehensive survey of the world's largest free-roaming giant tortoise population has revealed that the once endangered species is thriving on Seychelles' Aldabra Atoll. The survey, conducted by the Seychelles Islands Foundation (SIF) and the University of Exeter, estimated that approximately 180,000 Aldabra giant tortoises are living on the island. This number far exceeds the human population of Seychelles and marks a significant increase from previous estimates.
The new figure was obtained by a team that analyzed five years of tortoise counts between 2018 and 2022. This is the first update since a widely cited figure of 100,000 tortoises from the late 1990s. The study, published in the scientific journal Ecology and Evolution, found that the population was relatively stable during this period, with a best estimate of almost 183,000 adult and sub-adult tortoises.
The conservation efforts have paid off, with the tortoise population making a remarkable recovery from the brink of extinction. In the 19th century, exploitation of the animals meant there were fewer than 1,000 Aldabra tortoises left on the island. However, a recovery program led to it becoming a strict nature reserve in 1981 and a Unesco site in 1982. Researchers are now calling it one of the greatest conservation success stories of the Indian Ocean.
According to SIF chief executive Frauke Fleischer-Dogley, the new figure is proof of what long-term commitment to conservation can achieve. She expressed her delight at the news, saying it is wonderful for Seychelles, the world, and everyone who has worked to protect Aldabra. The study's findings have been hailed as a significant milestone in the conservation of the iconic Seychelles species.
Despite the good news, the study's authors warn that vigilance is essential to ensure the continued survival of the tortoise population. Aldabra's climate is changing, with longer and more frequent droughts predicted to reduce the shade and food available to tortoises, while rising sea levels threaten low-lying parts of the atoll. Invasive mammals, including feral cats and black rats, also remain a threat to the tortoises.
The study's authors suggest that the planned eradication of these remaining invasive mammals could lift the last barriers to further growth of the population and help it withstand future climate pressures. The findings have provided conservation managers with a reliable baseline to track future change and act early as the tortoises face increasing pressures. The study's results are a testament to the fantastic work done in the field and provide hope for the long-term survival of the Aldabra giant tortoise.
Key points
- The Aldabra giant tortoise population has reached a record high of 180,000 on Seychelles' Aldabra Atoll.
- The conservation efforts have led to a significant recovery of the tortoise population from the brink of extinction.
- Despite the good news, vigilance is essential to ensure the continued survival of the tortoise population in the face of climate change and invasive species.
