Giant tortoises on the Galapagos

Links to the past

In the early 16th century, when Spanish conquistadors were introducing the delights of Catholicism and colonialism to unsuspecting South Americans, the Galápagos Islands were stumbled upon by the fourth Bishop of Panama, Tomás de Berlanga. The bishop had been sailing to Peru, but powerful currents and a lack of wind took Berlanga to the previously unchartered archipelago. What he discovered on the islands inspired him to put quill to parchment and inform the Roman and Spanish Emperor of his adventures.

Berlanga described the islands as containing: “…muchos lobos marinos, tortugas, higuanas, galápagos…” which translates as “…many sea lions, turtles, iguanas, tortoises…” Although the ancient Spanish word for tortoise – galápago – changed over time, the name stuck for the islands. Unfortunately for tortoises their meat would also stick in the minds of visiting buccaneers, whalers and sailors, due to the ease of keeping them onboard ships until they could be slaughtered for food. It wasn’t until the arrival of US Naval Officer David Porter in the early 18th century that tortoises were considered as anything other than, ironically, fast food.

Captain Porter documented his travels in the Pacific as part of his book, Journal of a Cruise, in which he noted his observations of the types of tortoise that he’d seen on each island. The different shells were of particular interest to Porter, and would also be of interest to a certain Charles Darwin who read Porter’s journal in readiness for his own voyage of discovery on board the HMS Beagle in 1835. At the time the islands were known as the Archipelago of Ecuador; however, they were also detailed on maps as Insulae de los Galápagos – Islands of Tortoises. Today there are around 20,000 tortoises living in the Galápagos – not a patch on the 250,000 or so that would have greeted Tomás de Berlanga towards the end of the Middle Ages.

Lonesome George

In 2012 the only tortoise living on Pinta Island – Lonesome George – died, and so ended the Pinta Island species. George was an ambassador for the islands as well as a conservation superstar and considered to be one of the most important creatures on the planet due to his size, age and as the last known survivor of his species. The legend of Lonesome George lives on and his image has become an emblem for the Galápagos Conservation Trust and the Charles Darwin Foundation. A visit to the research station in Puerto Ayora on Santa Cruz is one of the best ways to learn about ongoing projects to ensure extinction doesn’t happen to any more of the islands’ sub-species. Tortoises at egg stage all the way through to adults – some of whom can grow to a metre and a half long and weigh up to 200kg – can be seen at the centre alongside other rescued reptiles, such as land iguanas and snakes.

Mating season for Galápagos tortoises

Hot weather, from January to May, tends to signal the start of the main tortoise courtship season, although mating can be seen at any point in the year. The ‘act’ can last quite some time, over a few hours, and involves the male balancing on its hind legs whilst omitting a loud roar-like squeal – the only time a tortoise can be heard other than the occasional hiss. Post-coital, the female can keep hold of fertilised eggs for up to four years, seeking out ideal nesting sites using her snout to check the ground temperature. South facing dry slopes are what the female ideally will be looking for.

Once she’s happy with conditions she’ll dig a hole with her hind legs before depositing the eggs one at a time, being careful to avoid eggs breaking in the process. The mother lays between two to 16 eggs at a time and she doesn’t have to lay all of her fertilised eggs in one go. Once eggs are laid the ground will be covered and warmed by the sun so as to incubate the eggs for around four months before they’re ready to hatch.