The Galapagos Giant Tortoise
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The ‘Galapago’
The Galápagos Islands got their name from the old Spanish word, ‘Galapago’. What is uncertain, however, is what the correct definition for this word actually is. Some historians believe it was a type of saddle which the carapaces (shells) of the giant tortoises closely resembled, while others believe it meant ‘tortoise’. What is clear is that it was these iconic animals that inspired the archipelago’s name, presumably due to the large numbers found here when the earliest visitors arrived.
Giant Tortoise population
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An estimated 200,000 to 300,000 giant tortoises once inhabited the islands. Today, the population is thought to be only 10-15% of what it once was, with many island-specific species sadly having become extinct.
Between the 16th and 20th centuries, more than 100,000 were taken away by pirates, whalers and merchants. As giant tortoises can survive without food or water for very long periods, sailors could keep them onboard and enjoy fresh meat weeks, or even months into their voyage.
The introduction of goats to the Galapagos in the 1950s destroyed much of the islands’ vegetation and further contributed to the demise of the giant tortoise.
Today, great efforts are made to rebuild these populations by collecting eggs from natural nests and rearing them in captivity, when they are at their most vulnerable, before releasing them back into the wild.
‘Diego’, the giant tortoise who saved his species
One individual who should be acknowledged for his significant conservation efforts is ‘Diego’, for this giant tortoise almost single-handedly saved his species from extinction. Originally taken from Española, the southernmost island in the Galapagos, he joined a breeding program in California’s San Diego Zoo in the mid ‘60s. At the time there were only 2 males and 12 females of his species (Chelonoidis hoodensis) left on Española and they were too spread out to reproduce. After 30 years in the states, he returned to the Galapagos, and continued his ‘work’ in a captive breeding program on Santa Cruz Island.
Thanks to his legendary libido, the breeding program was a great success and the population of Española giant tortoises is now thought to be well over 2000 individuals, of which an impressive 40% were fathered by Diego!
In 2020 the National Park announced the end of the breeding program, and at 100 years old, Diego returned home to Espanola Island where he was released back into the wild.
‘Lonesome George’ – the last of his kind.
Another legendary tortoise tale is that of Lonesome George.
In 1972 an extraordinary discovery was made on Pinta Island in the far north of the archipelago. A living male Pinta tortoise was found in the undergrowth. The Pinta species (Chelonoidis abingdonii) had been presumed extinct since 1906. This last surviving individual, estimated to be around 80 years old, was taken to a sanctuary on Santa Cruz where he lived out his remaining days by the name of Lonesome George.
Lonesome George died in June 2012, but can still be honored today at the Charles Darwin Research Station where he stands proudly on display within a glass cabinet, as a symbol of hope for endangered species around the world.
‘Harriet’: the world’s oldest giant tortoise
The oldest known giant tortoise lived for 175 years. According to Australia Zoo, ‘Harriet’ was taken from the Galapagos Islands in 1835 by none other than Charles Darwin himself, although there is some debate about this among historians. After living in England for a short spell, she was taken to Australia where clearly, she thrived in the warmer climate. She spent her last 20 years in Queensland-based Australia Zoo, owned by ‘Crocodile Hunter’, Steve Irwin.
The full life span of the Galapagos giant tortoise is thought to be at least 150 years old. Most species reach sexual maturity around 20-25 years and their growth rate is determined by how much food is available to them. Much like trees, their growth rate can be estimated by the number of rings found on the scutes (plates) of their carapace (shell). The Charles Darwin Research Station found one tortoise from Isabela to have put on 175kg in 15 years!
How did the giant tortoise get to the Galapagos?
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Most of the animals in the Galapagos originally came from the rainforests of South America, some 600 miles / 1000km away. Reptiles such as tortoises and iguanas would have been carried across on rafts of vegetation, or perhaps even floated across without aid (unlike their turtle . Unlike large mammals which wouldn’t have survived for more than a few days at sea without food or fresh water, reptiles such as tortoises are remarkably hardy and can survive for as long as a year without eating or drinking
How did Galapagos giant tortoises evolve?
The first giant tortoises are thought to have been washed ashore two to three million years ago. From there, they spread across the archipelago as new land emerged from volcanic eruptions, and evolved into several species (or subspecies – the taxonomy of the giant tortoise is subject to considerable debate), each unique to a specific island.
When Charles Darwin visited the islands in 1835, the British Vice-Governer told Darwin that he could tell which island a tortoise came from, just from the shape of its shell. This alerted Darwin to the slight differences between the animals on the different islands, an observation that Darwin almost dismissed without thought.
“I have not as yet noticed by far the most remarkable feature in the natural history of this archipelago; it is, that the different islands to a considerable extent are inhabited by a different set of beings. My attention was first called to this fact by the Vice-Governor, Mr. Lawson, declaring that the tortoises differed from the different islands, and that he could with certainty tell from which island any one was brought.
I did not for some time pay sufficient attention to this statement, and I had already partially mingled together the collections from two of the islands. I never dreamed that islands, about fifty or sixty miles apart, and most of them in sight of each other, formed of precisely the same rocks, placed under a quite similar climate, rising to a nearly equal height, would have been differently tenanted; but we shall soon see that this is the case. It is the fate of most voyagers, no sooner to discover what is most interesting in any locality, than they are hurried from it; but I ought, perhaps to be thankful that I obtained sufficient materials to establish this most remarkable fact in the distribution of organic beings.” Excerpt from The Voyage of the Beagle, by Charles Darwin, 1891 edition
As a sidenote, in his diaries, Darwin named the ‘British’ Vice-Governer as a Mr Nicholas Oliver Lawson. However a librarian at the National Library of Norway in Oslo discovered that this was not his given name, and that he was in fact a Norwegian by the name of Nicolai Olaus Lossius.
Giant Tortoises and Darwin’s Theory of Evolution
What Lawson, (or Lossius), had pointed out to Darwin was that tortoises’ carapaces differed in shape, depending on which island they inhabited. Darwin also noted that the vegetation and landscapes on each island differed significantly as well. Together with his observations of other species, he gradually put two and two together and realised that the animals had adapted to their own environments, and that this ability to adapt was what kept them alive for long enough to reproduce.
In the case of the giant tortoise he noticed that the species living in the arid, lowlands had long necks and shells that were bent upwards at the front like a saddle. This physical adaptation allowed the tortoise to reach vegetation not just on the ground (which is very sparse in the lowlands) but also higher vegetation as well, such as tree cacti. Tortoises with longer necks are also perceived as more dominant when settling social disputes over limited food resources.
On islands where there is an abundance of vegetation, such as Santa Cruz where Galapagos Safari Camp is based, tortoises have dome-shaped shells as it is less necessary for them to raise their heads.
There are currently 12 species of giant tortoise in the Galapagos Islands, two of which are native to Santa Cruz – the Eastern Santa Cruz Giant Tortoise and Western Santa Cruz Giant Tortoise, both of which are listed by IUCN as Critically Endangered, and can be viewed on our Safaris.
How did giant tortoises get so big?
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Although their large size was also thought to be an adaptation to island life, fossil remains on the mainland indicate that giant tortoises were once present there as well. Their demise is believed to be linked to man and the fact that the tortoises were easy prey for them. It’s also thought that the giant tortoises were better island colonizers than their smaller relatives because they would have been able to survive for longer periods of time without food and water, enabling them to reach the remote Galapagos Islands alive.
Today, adult Galapagos giant tortoises measure around 1.5m across the carapace and weigh up to 250kg, the same weight as a fully grown male lion!
When is the giant tortoise’s mating season?
The reproductive cycle of the giant tortoise is determined to a large extent by the climate, which is why there tends to be a fair amount of conflicting information relating to their mating season. On islands where there is a lot of vegetation, such as Santa Cruz, mating tends to take place towards the end of the Warm & Wet Season. Copulation can take several hours and is sometimes accompanied by loud grunts from the male which can be heard for many miles. The female then migrates to the lowlands to lay her eggs. She digs a hole in a shallow pit and fills it with a clutch of up to 20 pingpong shaped eggs. After covering the nest and urinating on it, she will leave the eggs to incubate for 120 to 140 days.
When the young hatchlings emerge they are vulnerable to large birds as well as ‘introduced species’ such as dogs, rates and dogs.
Best places to see giant tortoises in the Galapagos
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Regardless of how you explore the Galapagos Islands, whether its island-based or on a cruise, there are only a handful of visiting sites where you can see giant tortoises in the wild.
One of the most reliable places to find them is in the reserve just up the road from Galapagos Safari Camp. We like to take our guests to one of the lesser-known parts of the reserve, away from the coach-loads of tourists. Not only is it a more intimate wildlife experience but it also has one of the island’s most impressive lava tunnels that is well worth exploring.
We also see a number of giant tortoises within the grounds of Galapagos Safari Camp. As you drive up the long dirt track that connects the road to our camp, or chose to take an evening stroll, keep an eye out for them munching leaves on the side, or an ear out for them as they shuffle through the long elephant grass.
It is not uncommon to see them foraging under the Safari Tents as well, or working their way from one end of the camp to the other, via a network of little lava paths.
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There are an estimated 3000 giant tortoises on the island of Santa Cruz, and most are found in the highlands, where our camp is based. We consider it a great privilege to share their home and to be able to observe them up close, and so frequently in their natural habitat.
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Further Reading
A Sheltered Life: The Unexpected History of the Giant Tortoise by Paul Chambers.
A Sheltered Life is a fascinating look at one of the world’s strangest and most wondrous animals–whose significance in modern science and culture cannot be underestimated.
Darwin’s Tortoise: The Amazing True Story of Harriet, the World’s Oldest Living Creature, by Robin Stewart
This book, aimed at children of upper elementary level, tells the story of Harriet, a giant tortoise allegedly taken from the Galapagos by Charles Darwin in 1835, and how she ended up in Australia and lived to the ripe old age of 175.
Galapagos Giant Tortoise YouTube Playlist
Learn more about the Galapagos Giant Tortoise by watching our curated collection of videos on YouTube.
Plan your Galapagos Island Vacation!
See our Galapagos Safaris for suggested Galapagos itineraries and recommended activities, including plenty of time to meet these gentle giants in their natural habitat.
