Visiting the giant tortoises on Prison Island

Boulder-size tortoises are nestled together, munching casually on cabbage in the dappled sunlight. The oldest tortoise here is estimated to be 192 years old — the number is written on her back in blue paint. Her shell has a diagonal scar cutting into it, showing the remnants of an injury that has long since healed.

She is an Aldabra giant tortoise, part of a species that is continuously under threat of extinction.

This small plot of land on Changuu Island, which is located about five kilometers from Stone Town, Zanzibar, aims to protect the reptiles.

The tortoises don’t seem bothered by the groups of people who watch them ardently, thrilled by every small movement. A sign reading “Do not sit on the tortoises” denotes some of the problems that over-excited visitors bring with them.

Glenn Jolly, who manages the island, encourages visitors to scratch the tortoises and assures me that they love the attention. A stone path snakes through the conservation area, sporadically interrupted by tortoises that have spread out lazily beyond their muddy flat.

These tortoises are descendants of those living on the Aldabra Atoll islands in the Seychelles. Their population numbers ebb and flow due to poaching and responding conservation efforts.

Four tortoises were sent to Changuu Island as a gift from the British governor of the Seychelles in 1919. By the mid-1950s, there were more than 200 tortoises on the island. Jolly says the numbers began to drop when people started selling the animals as pets or for food to the extent that by 1996 only Seven were left!

Thanks to a dedicated team of conservationists, the numbers have risen once again to more than 100 with new generations of giant tortoises hatching every February.

Ten armed guards are present at the sanctuary at night to protect the gentle giants, which weigh an average of 250 kilograms.

Jolly says the main concern is that poachers will steal hatchlings, which are kept in a secure cage for the first months after birth. A conservation foundation is committed to ensuring their welfare, using the nominal visitor’s fee to sustain the population.

Jolly explains the fascinating biology of these animals to interested tourists.

“They have a resting heart rate of six beats per minute,” he says enthusiastically, adding that it’s a factor related to the tortoise’s long lifespan. “The oldest known tortoise of this species is in the Seychelles. They can live for 300 years.”

There are more than 100,000 Aldabra giant tortoises in the Seychelles, where they live in the wild. Documenting the age of these reptiles is difficult, and many researchers believe the oldest tortoise currently alive, named Jonathan, is 183 years old in Saint Helena.

The species nearly went extinct in the 18th century and the International Union for the Conservation of Nature views the animals as “vulnerable to extinction.”

The reptiles perform a similar role to elephants in grassland habitats, whereby their extensive foraging clears paths for other animals. The giant tortoises are known for having long necks, which allow them to stretch upwards and eat plants more than one metre above them.

Mexican biologist Jose Antonio de Alzatey Ramirez, who conducted research in the 1700s, called the tortoises the “ninjas” of the tortoise world because of unusual behaviour they exhibited. They are generally slow-moving and careful, however they can reach notable speed if pressed. When they are active, which is mainly in the morning scrounging for food, the tortoises may rise up on their hind legs to reach high branches, and can tip over onto their backs.

Changuu Island, also known as Prison Island or Quarantine Island, has its own fascinating history. The island was purchased by British First Minister Lloyd Matthews in 1891 after Zanzibar become a British protectorate.

He spearheaded the construction of a prison to house dangerous criminals, but there were never any prisoners kept there. Visitors, who often snorkel off the island, can still view the prison compound which is now home to a pleasant restaurant and ocean vista.

Though it wasn’t used as a prison, the island served another purpose for years. It was used as a quarantine station in 1923 to combat the spread of yellow fever. The prison complex was turned into a hospital. Ships that were sailing to Zanzibar would send suspected cases to the island, where patients would be monitored for one to two weeks before continuing on. The expansion of hospital buildings meant that at it’s peak, the quarantine station could house over 900 patients. Changuu Island offers an offbeat, fairy-tale world to interested tourists in Zanzibar. I felt transported back to a prehistoric world when I fed a giant tortoise in his early hundreds. I was reminded that this species was on the verge of extinction, and needs to be protected.

He picked the bright-green cabbage leaves out my hand, blinking occasionally, and seemingly unimpressed by his surroundings. He has likely seen it all by now.