Let’s begin our exploration of the incredible fauna of the Galapagos with their namesake, the Galapagos giant tortoise!
These are, of course, one of the most famous Galapagos animals, and, appropriately, our first animal sighting on our first stop in Santa Cruz! I had assumed getting a glimpse of a tortoise in the wild would require an expedition into the long bush of the highlands. To this end, I brought binoculars, hoping to spot specimens in the distance.
But we’d been in the Galapagos all of 20 minutes when our pickup truck taxi pulled over at the side of the one road on Santa Cruz island, friendly Rodrigo indicating a ‘tortuga’ ahead. Lo and behold, having strolled in under the wire fencing, was our first tortoise: casually passing through somebody’s ranch, right alongside the road!
After this exciting initial stop, we gave up all pretense of settling in slowly and headed straight for the Charles Darwin Research Station to learn more about these gentle giants! The center does important tortoise research and assists in managing their population.
There are now 12 subspecies of Galapagos giant tortoise, differentiated by distinctive keratin-plated shells. Individuals from populations on older, flatter and drier islands have the characteristic ‘saddleback’ shell shape. This adaptation allows the tortoises to extend their necks upwards to browse on cacti and low brush.
The tortoises native to Santa Cruz and other, younger islands with humid highlands have dome-shaped shells. They don’t require the peaked shell opening, as these guys mainly graze on grasses.
At the research station, we got to compare directly as we wandered among members of many of the extant species. Bonus: we got to admire the resident creche of baby tortoises! To ensure population continuation, center staff take eggs from vulnerable nests, then incubate and raise the young tortoises. The goal is to release healthy individuals back into the wild: a process that takes about five years.
Eager for more, a couple of days later, we returned to the highlands where we’d seen our first Galapagos giant tortoise. These ancient reptiles live over 100 years in the wild, and can attain massive sizes of nearly a ton. It’s possible to estimate their age by looking at the rings on their shells! Unlike trees, however, the older a tortoise is, the less visible these rings become as the elements take their toll.
For a cold-blooded reptile, the damp, misty highlands get quite chilly at night! But there’s a clever solution: they simply hop into one of the reserve’s warm, mud-filled, natural ‘jacuzzies’ for the night!
You may know that nest temperature determines the sex of turtles and tortoises. Cooler temperatures produce more males, while warmer temps produce females. The different tortoise subspecies lay different numbers of eggs and build varying numbers of nests, dependent on annual conditions. One similarity is that female tortoises are always smaller than males. Another similarity: all subspecies reach maturity around age 20.
Our tortoise sightings did not stop on Santa Cruz! We later visited a satellite research station on Isabela Island. This largest of the Galapagos islands boasts 5 distinct subspecies – mainly in its rugged, inaccessible interior. We had the privilege of sharing the road with one subtype on a morning run 🙂
In sum, Galapagos giant tortoises are incredible, long-lived, adaptable beings. It was thrilling to see them in person, both in the wild and at the two conservation centers we visited. If you want to learn more about them, there’s resources here, here and here.