Giant Tortoises at Prison Island, Zanzibar

 

Aldabra Giant Tortoises

Tortoise Sanctuary, maintained by Save the Tortoises Foundation at Prison Island of Zanzibar, Tanzania a great tourist attraction. Aldabra giant tortoises are kept there and bred in captivity. One can see, touch and walk side by side of many such humble giants. It is indeed an awesome experience. However, tourists are advised not to get tempted to ride the tortoises!

On the runway

Aldabra giant tortoises are natives of Aldabra of Outer Islands of Seychelles in vast Indian Ocean. Seychelles is an archipelago country of western part of Indian Ocean, located at about 930 miles east of Africa and northeast of Madagascar. Aldabra is a coral atoll which is second largest in the world. While, the giant tortoises have got their name from Aldabra Island, the island has the genesis of its name from 'Al-Hadra' or 'Al-Khadra', as it was called by the Arab sea traders of 15th - 16th century.

In 1919, first two pairs of Aldabra giant tortoises had arrived at Zanzibar from Aldabra as precious gift from the British Governor of Seychelles to his counterpart Major F B Pearce (1914-1922), the British Resident of Zanzibar. The tortoises had survived arduous sea journey onboard S S Troba to Zanzibar. As return gift, a number of exotic flower plants were shipped from Zanzibar to Seychelles.

Floating dhows (country boats) to ferry from Zanzibar to Prison Island

Upon arrival at Zanzibar, one pair of Aldabra giant tortoises was kept in the British Residency Garden (today's State House) and another pair was accommodated in the garden near Mathews' Memorial (presently Peace Memorial Museum), Zanzibar. Over a period of time they bred and grew in numbers. Problem arose when locals started stealing tortoises.  Tortoises were sold both as exotic pet as well as delicacy at high end restaurants. To tide over the problem, tortoises from the garden of Peace Memorial Museum (Beit el Amani) were shifted to the garden of National Museum of History and Culture (Beit el Ajaib) and ultimately from there to the Prison Island. Gradually all the Aldabra giant tortoises were shifted from Zanzibar to Prison Island.

Walking alone

At Prison Island, their numbers multiplied and within a span of nearly forty years (by 1955) the head count reached up to 200. But in post-independence era (1964 onwards) of Zanzibar, local populace again indulged in theft of tortoises. Due to theft of tortoises, the population of Aldabra giant tortoises started plummeting in the island. It came down to about 100 tortoise (by 1988) and the southward journey of number continued to 50 (by 1990) and at an alarming level of meager 7 (by 1996). At that point of time, to boost the tortoise population 80 tortoise hatchlings were once again brought into Prison Island. However, the result was disappointing as it lacked local awareness and support. Afterwards, with the support of World Animal Protection (then called World Society for the Protection of Animals) the trend was reversed. Save the Tortoises Foundation came into existence. Conservation efforts for Aldabra giant tortoises bore fruits. By the year 2000, the number rose to about 150 including adults, babies and hatchlings. Now with conservation management their numbers are increasing under captivity in the island.

Best foot forward

In ancient days, there were several varieties of giant tortoises on this earth. Barring Antarctica and Australia, they were found in many islands of different continents of the world. Scientists have proven their existence through fossilized findings. 

In their company

Believe it or not, in the food chain of nature there is no ‘official’ predator for an adult giant tortoise and human being is exclusively responsible for its extinction. Several man made factors have played in their extinction. Firstly, ruthless killings by adventurous European sailors for both meat and eggs, hunting by the dogs, pigs and rats which came along with the human settlers in these islands, grazing cattle & goats, which had eaten away their routine food at the grass root level etc. Due to all these combined factors the names of many varieties of giant tortoises have been added in the ever increasing list of extinct creatures. Sad but true, in between 1700s to 1800s, we've achieved this notorious feat.

A busy traffic lane

Today they are surviving in limited geographic locations like Galapagos Islands & other islands of Seychelles, Reunion Island etc. Simultaneously, they are being bred in captivity in Prison Island of Zanzibar, Tanzania. Also in La Vanille Reserve des Mascareignes, South Mauritius where they were imported from Seychelles in 1880s as per the advice of Charles Darwin. 

Sad, they are extinct (Stamp courtesy: Ranjan Mahapatra)

Another breeding project has been undertaken since July 2007 at The François Leguat Giant Tortoise and Cave Reserve, Rodrigues, Mauritius. There Aldabra giant tortoises have been sourced from breeding farm of La Vanille in the 1980s.

A course correction

At Prison Island, one can spend hours watching the behavior and movements of these slow moving giants. A close look at a mature tortoise reveals that the carapace i.e. the outer shell of the Aldabra giant tortoise is dome shaped like any other tortoise but much bigger in size. The protective domes are dark brown or black in color. The front to end length of carapace of male tortoises averages about four feet while that for the female counterparts it is about three feet. The carapaces of male tortoises are longer and lower. These have widened near the long and thick tail. While the female variety weighs on an average 160 kilograms, the male species are bigger and heavier with average weight of 250 kilograms. However, smaller sizes and weights are found in specimens, who are preserved in captivity at different conservation centers.

 

'I'm a bit shy'

Their front and back feet have powerful claws. Their limbs are robust and are covered with bony scales. Head is small yet pointed. The neck is extraordinarily long. Their gait is something to be watched about. With small limbs and heavy weight of the body they move at very slow motion. Inside the enclosure there are small shallow puddles of water where they prefer to take rest. The walkway inside the park like enclosure, is dotted with a number of Aldabra giant tortoises of various sizes. They roam across the pathway, munch the fallen leaves from the shade trees, take rest as long as they want and again move. However, juvenile tortoises are kept in a similar but separate enclosure.  The breeding program of Aldabra giant tortoises at Prison Island is successful which can be gauged from the number of habitat tortoises there.

In a huddle

The sexual maturity of Aldabra giant tortoises is attained at the age of 25-30 years. More than age, it is their physical size that determines their reproductive stage. February to May, are the months of breeding of this species. They can reproduce twice a year depending upon several parameters. Female Aldabra tortoise lays 4-14 rubbery eggs at a time at a shallow soft sandy location, out of which nearly 50% are hatched in the given wild habitat conditions. However, under the conditions of captivity, the average clutch size increases to 9 -25 eggs.

 

Raindrops on my armor

The incubation period varies according to local temperature. Warm environment favors faster incubation, say 110 days (three and half months nearly) while with drop in ambient temperature it can be about 250 days (eight months approx.). Hatchlings emerge from the eggs sometime between October to December.

 

Juveniles

The age of Aldabra tortoise is something to be astonished about. The estimated lifespan is more than one century. It extends somewhere between 150-200 years under favorable environment. Their aging is marked on the carapace by radial striations or growth of rings which happens due to concentric addition of tissues.

Here and Tortoise. Who will win the race?

A ‘live’ example of long life is the case of a male Aldabra giant tortoise which had died at Alipore Zoological Gardens at Kolkata, India on 22nd March 2006. His name was ‘Adwaita’ which in Sanskrit language means unique. It is said that he was brought from Aldabra and was gifted by the British sailors of East India Company to Robert Clive, the then Governor of the Presidency of Fort William, Bengal of British Empire in India. Adwaita was kept as his pet at his residence of Barrackpore near Kolkata and later on shifted to the said zoo, in the year 1875 or 1876 by Carl Louis Schwendler, the founder of the Alipore Zoological Gardens at Kolkata, India. At the time of demise, his age was estimated something around 200 years. It will not be out of point to mention that the writer had seen him alive during a trip to the zoo, early Nineteen Seventies. He was seen resting peacefully within his enclosure, ultimately where he rested in peace, forever. 

India post has issued first hexagonal stamps on Aldabra Giant Tortoises on 02 Aug 2008 stamp.

One of the sheet-lets issued

Aldabra giant tortoises are considered as herbivores.  The diet for Aldabra giant tortoise is low grazing vegetation viz. grass, leaves, herbs & shrubs, stems of woody plants etc. Though they live on vegetable diets, at times they feed on carrion and small invertebrates and insects. In the wild, they travel long distances in search of food, crossing sandy soils as well as rocky surfaces with equal ease.

Feeding schedule

At Prison Island, the diet for the tortoises in captivity additionally includes fruits like banana, tomato, carrot, bean, pea, pear, apple, nuts, grains etc. To supplement the diet with nutrients, they are given compressed vegetable pellets. Here tourists are advised not to feed the tortoises. Feeding of the tortoises is done by the caretakers at fixed times, twice daily – at 10 am and 4 pm. Fresh mango peels are savored equally well by the adult as well as juvenile Aldabra giant tortoises of Prison Island.

Feeding hungry giants

Conservation of this species under ‘vulnerable’ category of International Union for Conservation of Nature (IUCN) Red list is being done with earnest efforts under captivity at selective places. However, its original place viz. Aldabra atoll is under new threat. The natural habitat of these tortoises at Aldabra atoll in Indian Ocean is threatened by gradual rise of water level of ocean due to global warming. Unless the trend of rising of global temperature is reversed, the last bastion of this beautiful and harmless creature will find a watery grave.

 

'Blessings of long life' - to whom?

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The information provided in the article is for general informational purposes only. All information is provided in good faith. This is only for the sharing of knowledge of Philately with philatelist fraternity. No commercial angle, whatsoever, is involved. Under no circumstances I shall have any liability for reliance on any information provided in the story.