The Galapagos Islands have been instrumental in the study of evolution dating back to the 1830s when Charles Darwin visited here. After his voyage on the HMS Beagle, Darwin developed his famous theory of natural selection. Although his research was largely based on Galapagos finches, the giant tortoises also have an evolutionary story to tell.
Chelonoidis nigra have approximately 11 subspecies, each one occurring on a different island or volcano in this Pacific Ocean archipelago. Each distinct subspecies developed individual characteristics to suit the conditions in which it lived. Briefly, the tortoises eat grass, flowers, and cacti; and being land reptiles and weighing over 500 pounds each, their physical range is limited. So on islands where the grass is longer, for example, the tortoises have evolved to have a more suitable long neck and accommodating carapace (shell) for this condition.
After two centuries of over-harvesting by whalers and sea-goers for the fresh meat, the giant tortoises became dangerously close to extinction. Feral animals later introduced by visitors to the Islands also added to the destruction of the species. This is a creature who lives over 100 years–one of the world’s longest living animals–and yet the population was nearly wiped out by the middle of the 20th century. When The Galapagos Islands were designated as a national park in 1959, the tortoises were nearly extinct.
On Santa Cruz Island the Fausto Llerena Tortoise Center began the noble effort of rebuilding the population with a captive breeding program over four decades ago. I visited this Center and witnessed their remarkable work. They raise the young (adorable) in the Center for the first five years of the tortoise’s life, then release them to the wild, monitoring their progress and protecting them from feral non-native predators. The program is run jointly by Galapagos National Park and the Charles Darwin Foundation. To read more about the Center, click here. Last week in the news it was reported that the tortoises on the Galapagos Island of Espanola were officially saved from extinction (link here).
We ventured into the highlands on Santa Cruz Island where the giant tortoises live in the wild, and spent the day quietly observing this slow-moving, but spirited, animal. To see this venerable creature still living and breathing on our planet is a testament to conservation.
Photo credit: Athena Alexander