Aldabra Giant Tortoise
The Aldabra Giant Tortoise, Geochelone gigantea, is one of the largest tortoises in the world. It is found on the islands of the Aldabra Atoll in the Seychelles. The atoll has been protected from human influence and is home to some 152,000 giant tortoises, the world’s largest population of the animal. Another isolated population of the species resides on the island of Zanzibar. The tortoises exploit many different kinds of habitat including grasslands, low scrub, mangrove swamps, and coastal dunes.
Its shell averages 47 inches in length and it weighs approximately 550 pounds. The shell is dark gray or black in color with a high domed shape. It has stocky, heavily scaled legs to support its heavy body. Its neck is very long, even for its great size, which helps the animal to exploit tree branches up to a meter from the ground as a food source. Females are generally smaller than the males, weighing up to 330 pounds.
The Aldabra has two main varieties of shell. Specimens living in habitats with food available primarily on the ground have a more dome-shaped shell with front extending downward over the neck. Those living in an environment with food available higher up off the ground have a more flattened topped shell with the front raised to allow the neck to extend upward easily.
They are most active in the mornings when they spend time browsing for food. Primarily herbivores, Aldabra Tortoises will eat grasses, leaves, and woody plant stems. They occasionally indulge in small invertebrates and carrion, even eating the bodies of other dead tortoises. In captivity, Aldabra Giant Tortoises are known to enjoy fruits such as apples and bananas as well as compressed vegetable pellets. There is little fresh water available for drinking in the tortoises’ natural habitat, therefore they obtain most of their moisture from their food.
Aldabra Giant Tortoises reach sexual maturity when they attain about half their final size. It seems that reaching sexual maturity is determined by size, not by age. Between February and May, females lay between 9 and 25 rubbery eggs in a shallow, dry nest. Usually less than half of the eggs are fertile. Females can produce multiple clutches of eggs in a year. After incubating for about 8 months, the tiny, independent young hatch between October and December.
While they are characteristically slow and cautious, they are capable of appreciable speed, especially when tempted with a treat. They are also known to attempt perilous acrobatic feats, rising precariously on their hind legs to reach low branches. They risk death by tipping onto their backs and being unable to right themselves. They are also excellent swimmers, being naturally buoyant. This factor has allowed the spread and eventual speciation of many kinds of related tortoises across the Indian Ocean