Giant tortoises

Keeping the Seychelles Island Giant Tortoises Off the Endangered Species List:

Many people know the story of Lonesome George, the last of the Pinta Island Tortoises, yet what people do not realize is that the Galapagos Tortoise is just one of many species of Giant Tortoises that were exterminated after the first human settlers arrived on their islands. An article in the most recent issue of Chelonian Conservation and Biology takes an in-depth look at the decline of the Giant Tortoise in the Seychelles Islands and determines which islands could best support the reintroduction of new Giant Tortoise populations and survive the climate change which threatens to eliminate many of their natural habitats.

Many people know about the Galapagos Giant Tortoises being almost extinct and know the story of Lonesome George, the last of the Pinta Island Tortoises. However, what people do not realize is that the Galapagos Tortoise is just one of many species of Giant Tortoises that were exterminated after the first human settlers arrived on their islands. This has been a major problem in the Indian Ocean, especially in the Seychelles Islands, where only one natural population is still in existence.

Eight to 12 species of Giant Tortoises originally roamed the Indian Ocean islands, but when human populations began to settle, these creatures were hunted for meat, sport, and even captured to be household pets. It is also believed that their offspring, while still in egg form, fell easy prey to dogs, rats, cats, and other newly introduced island predators. The article “Giant Tortoise Distribution and Abundance in the Seychelles Island: Past, Present, and Future,” in the journal Chelonian Conservation and Biology takes an in-depth look at the decline of the Giant Tortoise in the Seychelles Islands through an expansive time range beginning in the early 1600s, and takes the reader on a journey through time and the unfortunate decline of these magnificent creatures.

The population size and suspected origin of Giant Tortoises on 38 of the Seychelles Islands are compared at different time periods. These data provide an effective basis for determining which islands could best support the reintroduction of new Giant Tortoise populations.

Some key factors that seem to be of great concern when considering any of these islands is the amount the sea level will continue to rise over the next 100 to 200 years. With tortoises creating nests so close to the water, the fear is that their natural habitat will not survive very long, even if the island has all the other qualities that would allow for a long-term home. Scientists do believe this could be offset by a lack of rainfall that would occur simultaneously as the sea level rises to keep the balance, but that cannot truly be predicted.

One very interesting occurrence that happened when attempting to reintroduce the Aldabra giant tortoise to Mauritius Island was that the grazing pattern of the tortoise seemed to increase germination for the rare Mauritian Ebony tree and help the overall balance of the island’s ecosystem. Initial results of Giant Tortoise reintroduction seem positive, but close monitoring and care will need to be a priority as this delicate balance takes place.

Seychelles giant tortoise photo © Thomas Reich

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