Aldabra giant tortoise  (Geochelone gigantea)

The Aldabra giant tortoise is classified as Vulnerable (VU) on the IUCN Red List (1), and listed on Appendix II of CITES (3). In most legislation it is listed as Geochelone gigantea, although it is also referred to as Dipsochelys dussumieri or D. elephantine (4).

The Aldabra giant tortoise is indeed a giant, with individuals reaching over one metre in length (2). The thick, domed carapace is dark grey to black in colour and the robust limbs are covered in bony scales, as is the small, pointed head (5).

Endemic to the islands of Aldabra and the Seychelles in the Indian Ocean, populations of the Aldabra giant tortoise have also been introduced to Mauritius, Reunion (6), and granitic islands of Seychelles such as Curieuse and Fregate (7).

The Aldabra giant tortoise inhabits a wide variety of vegetation on the islands where it is found, from scrub and mangrove swamp to grassy plains known as 'platins' (2).

The breeding season occurs from February to May (5), and females lay small clutches of 9 to 25 eggs, of which less than half are fertile in the wild (2). Hatchlings emerge anything from 3.5 to 7 months later. The Aldabra giant tortoise has a predominately vegetation-based diet although it will supplement this intake with carrion (2) (7).

Giant tortoises throughout the islands of the Indian Ocean represented an important food source for sailors visiting these shores in the 17th to 19th Centuries and live individuals were often captured and stored for meat in the ship's hold (2) (7). In addition, the destruction of habitat and the introduction of mammalian predators such as rats and cats, and competitors such as goats further decimated the previously isolated populations (2). The Aldabra giant tortoise is one of only three giant tortoises in the area to survive today, as a result of this past exploitation (8), and the only one to survive in the wild, with the others surviving only in a captive breeding programme (4) (8).

Charles Darwin himself was involved with gaining this species protection in the Aldabra Atoll (2). International trade is restricted by the listing of the Aldabra giant tortoise on Appendix II of the Convention on International Trade in Endangered Species (CITES) (3), and there is a captive breeding programme of these giant tortoises on the island of Mauritius (2).

View information on this species at the UNEP World Conservation Monitoring Centre.

To find out more about the Aldabra giant tortoise, see: 

• Aldabra and Seychelles Giant Tortoises:
  http://islandbiodiversity.com/tortoise.htm#Giant%20Tortoises