GALAPAGOS - The Giant Tortoises

The giant tortoise is certainly the islands’ most celebrated resident.  The tortoise population has suffered badly at the hands of humans and it would perhaps no longer have survived but for recent intervention. There were once over 200,000 tortoises on the islands but this has now been reduced to about 15,000. Between the 1500s and 1800s, a great number of tortoises were taken by sailors for food.  The tortoises could remarkably remain alive, upside-down in the holds of vessels, for up to a year with no food and water.   Numbers dropped further because pirates, whalers, sealers and colonists introduced mammals such as goats, dogs, pigs and donkeys.  This increased the competition for food, damaged nests and often led to eggs and young hatchlings being taken.  These introduced species are still causing a problem to this day.

The giant tortoise in the wild may grow to a weight of about 270kg and a length of over 1.2 metres. It is difficult to estimate maximum ages but they can certainly be expected to live well over a hundred years. There are two distinct shapes of carapace (the domed part of the tortoise’s shell) – namely the “saddleback” and the “dome-shaped”.  

The saddleback tortoise is found in the more arid parts of the islands (such as Espanola and Pinzon) and is generally more aggressive in behaviour.  During such dominance contests, it will stretch its neck and front legs to give extra height.  This is normally restricted to posturing and there is little fighting.  The additional height is also a benefit in seeking food. The front of the saddleback tortoise shell is raised but this lesser protection is not a problem in its habitat and there are no predators to take advantage of the exposed skin. The dome-shaped tortoise is found in moist areas with plenty of lush vegetation and lots of water and shade.  This tortoise is much more typical of the rest of the world’s tortoise species.  It has no need of extra height as it will normally just trundle through dense undergrowth trampling and eating the grass.  The front end of its shell is closed allowing it to retreat into an almost fully protected casing.

The best places to see giant tortoises in the wild are the highlands on Santa Cruz Island or the Volcan Alcedo area on Isabela Island.