An Asian brown forest tortoise walks along a river bed. – Photo by Rushenb
AS a six-year-old child one of my favourite Christmas presents was a book entitled ‘Aesop’s Fables’, which I assiduously read over and over again. I particularly liked the story about ‘The Hare and the Tortoise’, written initially in Greek, 2,700 years BP (before the present).
The following year, my sister and I were given two pet Mediterranean tortoises by our parents and these we religiously fed daily on fresh wild dandelion leaves picked from hedgerows and lettuce leaves left over from summer salads. At the end of autumn, as their metabolism slowed down, we would place them in a nest of straw for their winter hibernation in a garden shed. As soon as the middle of spring emerged, we would see if they had awoken and, if so, set them loose in our back garden, after first bathing their eyes and later oiling their shells with linseed oil thus giving them literally ‘a spring clean’. A few years later, they broke out of our garden and, despite constant searches in our vicinity, we never saw them again.
Later in married life, we bought our two young daughters a tortoise each as our children were astounded to see them caged in a small enclosure in a pet shop window. Our neighbour’s children also had two tortoises. When they moved elsewhere, we acquired their tortoises plus another lost and stranded larger tortoise.
We thought our garden was tortoise escape proof until one of the smaller ones tunnelled under the stout wire garden fence. We instantly asked neighbours to help us search for him, but to no avail. Word had got around the community, as a year later he was found 5km away from our garden and returned to us. This tortoise in his travels had crossed hectares of school playing fields, pine forests, and even over a railway line with very regularly running trains to the nearest town.
‘Once bitten, twice shy!’ as the old saying goes, but I had been bitten twice by lost tortoises. Upon our next family move to a school in Somerset, our garden was a very insecure place to keep tortoises with a main thoroughfare nearby, so we reluctantly donated all five tortoises to a nearby tortoise breeding sanctuary, much to our children’s initial disapproval, for they liked tickling their extended necks, but their eventual understanding. Tortoises of various sizes and shapes seem to have haunted or even hunted me for much of my life.
Bornean tortoises
Considered as one of the most primitive living tortoises, the Asian forest tortoise (Manouria emys emys) is the largest tortoise inhabiting Southeast Asia and ranges from peninsular Thailand and Malaysia into Borneo and Sumatra. Weighing about 25kg to 35kg and with a shell length approaching 50cm, it usually lives in moist, higher altitude, broad leafed forests that experience monsoonal rainfall.
In the dry monsoon, it has been seen to visit shallow pools of water and to draw in water through its nostrils. Like most species of tortoise, in the warmer parts of a day, it searches for pools of water in which to soak, hides in the shade, or even burrows underground into damp soil. Herbivorous in its dietary requirements, it particularly enjoys midin.
It is the only species of tortoise that builds a nest above ground level to hatch and fiercely guard its clutch of 50 eggs. As with other species of Malaysian tortoises, little is actually known about their numbers but sadly it is becoming an endangered species and now a victim of the illegal exotic pet trade.
Another very much smaller and more common species of tortoise, Geomyda spinosa, is found amongst leaf litter in the rainforests. Owing to their flattened shells with sharply pointed edges, which resemble the tips of leaves, the little tortoises are well camouflaged on the forest floors. Not a lot is known about Bornean tortoises but certainly we know that unlike turtles, whose eggs resemble those of snakes because of their leathery appearance, tortoise eggs have hard shells not unlike those of crocodiles.
A giant Galapagos tortoise stands in a field.
Giant tortoises
Such lumbering giants once roamed Eurasia, Africa and the Americas. Today, they are mostly found in the archipelagos of the South American’s Galapagos Islands and in the Indian Ocean’s Seychelles and on Madagascar. Up to 1.5 metres in length and weighing up to 420kg, it was originally thought that their huge proportions were due to ‘island gigantism’ implying that they had successfully adapted to island environments as they did not face the same predators as their mainland relatives. This idea holds little strength today as we know they appeared once on the continental mainlands but began to disappear during the Pleistocene Ice Ages (1.4 million to 10,000 years BP) and even more rapidly when Homo sapiens appeared in his hunts for meat.
Aldabra giant tortoise
It was on a visit to the small Indian Ocean island of La Digue, in the Seychelles archipelago, that I first met these creatures – Aldabrachelys gigantea. I was looking for a particularly remote beach to view the Henry Moore-like rounded, granite sculptured rocks carved by the elements and the waves. Trekking along the sandy beaches, fringed by rainforest, grasslands and swamps, suddenly I came across two of these tortoises as they stretched their necks out to reach up to the lower foliage of the trees.
A week later, I landed on a remote island village in northwest Madagascar where all the villagers, including the children, had ochre-painted tortoises on their foreheads and arms. Upon further enquiry I was told that these people revered the giant tortoises that they saw in their rainforests and they would feed these giants whenever they waddled into their village during the dry monsoon time.
This year, this species of tortoise, with its huge dome-like shell or carapace, is the only Indian Ocean giant species still alive. Recorded by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (Cites) endangered species list in the vulnerable to extinction class, fortunately captive breeding programmes have been successful. The female lays a clutch of 25 eggs in a shallow nest, scooped out of silica rich soil, between February and May, with the eggs hatching at the start of the rainy season.
These tortoises can survive the dry season by their capacity to snort up water from the shallowest of pools. Sadly, both eggs and hatchlings are prone to predation by large lizards. However, reaching sexual maturity at about 30 years of age, they can live for 80 to 120 years.
Galapagos giant tortoise
Ten species of this giant still exist today on scattered islands there. They arrived from Ecuador about three million years BP on vegetation rafts, which drifted there on ocean currents to the islands. Originally there were 16 species, but hundreds were plundered by privateers, whalers, and sealers as living food for their crews to stow away live aboard their ships until eaten. Today only 20,000 to 25,000 wild tortoises remain on those islands.
Generally, two specific subtypes can be identified by the shape of their shells –saddleback and domed. The former are found in the more arid regions with longer necks and legs, feeding on cacti, while the latter live off grasses on the more vegetated islands. Most of these giants rest for up to 16 hours a day but they have voracious appetites. They mate between January and May, laying a clutch of 25 eggs in the June to December cool season.
Their underground nests are scooped out of lowland sandy soils. Upon hatching, their gender is determined by the ambient temperature of their nests. Warmer temperatures produce more females. In 2015, a new and slightly smaller species was identified on Eastern Santa Cruz Island and is appropriately named Chelonoidis donfaustoi, after Don Fausti, who devoted his whole working life to the conservation and protection of tortoises as a park ranger.
Perhaps you may remember the media reports of the passing in 2012 of ‘Lonesome George’ at the age of 100. He was a giant Galapagos tortoise of the last of his species (Chelonoidis abingdonii), who was found alone on Pinta island in 2005 and taken to a conservation centre. The rest of his species was wiped out on the island by the introduction of three goats, which by 1970 had grown in population to over 40,000 and overgrazed the island’s vegetation. In 2010, these wild goats were destroyed allowing a renewal of the original vegetation.
Lonesome George’s legacy
International geneticists have researched this giant tortoise’s genes together with the DNA of another Aldabran tortoise, to find that their specialised genes allow them longevity, immune resistance to diseases, and cancer resistance that other vertebrate animals lack. Genes that link longevity to humans were also found in these tortoises. Lonesome George did not die in vain.