- Common Name
- Aldabra tortoise, giant tortoise
- Testudines (somes sources cite as Chelonia)
- Genus Species
- Geochelone (land turtle) gigantea (giant)
- They are dark gray to black in color with a highly domed thick carapace, a very long neck to aid in food gathering, and short, thick legs.
Male: Males have longer, thicker tails than females.
- Male: Mature males have an average carapace (shell) length of 122 cm (4 ft.)
Female: Adult female carapace length averages 91 cm (3 ft.).
- Male: Adult males up to 250 kg (550 lb.) or more
Female: Mature females average 159 kg (350 lb.)
- Though it feeds primarily on vegetation, the Aldabra tortoise is flexible and opportunistic in its diet. In order to obtain enough nourishment for survival, the tortoise may supplement its diet with small invertebrates and even carrion (including dead tortoises).
- Incubation is temperature dependant: in warm temperatures, eggs hatch in about 110 days; in cool temperatures, eggs take 250 days to hatch.
Clutch Size: Typically, the females lay between 4 to 14 eggs, of which less than one half are fertile. Within zoological settings, the average clutch size may be seen to increase, approaching 9 to 25 eggs.
- Breeding Period
- In healthy, uncrowded populations, a second clutch (laying) within the same breeding season is likely.
- Sexual Maturity
- Sexual maturity is determined by size rather than by age; most species begin to reproduce when they reach approximately half their full-grown size, usually around 25 years of age.
- Life Span
- Unknown, probably easily lives over 100 years
- The entire wild population of Aldabras is restricted to the Aldabra Atoll (a small group of coral islands in the island nation of Seychelles, north of Madagascar).
- There are many different habitats on the islands where tortoises can be found, including scrub, mangrove swamp, and coastal dune. The largest concentrations of tortoises are found on the grasslands called platins.
- Global: No data
- IUCN: Vulnerable
CITES: Appendix II
USFWS: Not listed
- The Aldabra tortoise is the largest animal on the atoll. The tortoises fill a niche very similar to the one occupied by elephants in Africa and Asia. As with elephants, they are the main consumers of vegetation and noticeably alter the habitat during their search for food. Tortoises have been known to knock over small trees and shrubs to obtain nutritious leaves. This makes pathways and clearings within the forestlands for other animals. Seeds pass through the tortoise's digestive tract and eventually become food for many other species.
- The Aldabra tortoise is one of the longest-lived animals on earth, if not the longest. No one knows exactly how long these animals are capable of living, but they are believed to easily surpass 100 years. So far, the tortoises studied have outlived the scientists studying them, and proper records have not been maintained.
Ecology and Conservation
The Aldabra tortoise is the only remaining species out of 18 former species of tortoise that once flourished on the islands of the Indian Ocean. The others went extinct because of hunting by sailors and the predation of eggs and hatchlings by introduced species such as rats, cats, and pigs.
This was one of the first species to be protected in order to ensure its survival for the future. Charles Darwin and other notable conservationists of the day along with the governor of Mauritius set aside a captive breeding population on Mauritius as well as protecting the Aldabra Atoll.
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Gibson, C.W.D. and Hamilton, J. "Population Processes in a Large Herbivorous Reptile: The Giant Tortoises of Aldabra Atoll." Occologia (Berlin), Spring-Summer, 1984, pp. 230-240.
Grubb, P. "The Growth, Ecology, and Population Structure of the Giant Tortoises on Aldabra." Phil. Trans. Roy. Soc. Lond. B, Vol. 260, 1971, pp. 327-372.
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