Bonus content from the May 2012 REPTILES magazine article "Miracle Babies!"
The Galapagos tortoises (Chelonoidis nigra) are the undisputed king of the tortoise family, but the Aldabra tortoise (Geochelone gigantea) is a close second in size. These two species may be difficult to distinguish due to their similarities in size and coloration. The common method of identifying an Aldabra tortoise is to look for the presence of the nuchal scute, which is generally present above the neck. The Galapagos tortoise lacks a nuchal scute, and has a more rounded head.
These two giant tortoises are both island species, named after the islands where they originated. There are multiple species or subspecies of both. There are generally 10 to 15 different species of Galapagos tortoises recognized from seven volcanic islands of the Galapagos archipelago. There are three species of Aldabra tortoises generally recognized, not including extinct species.
Perhaps the biggest difference for the hobbyist who may consider acquiring one of these species is the permit requirements. The Galapagos tortoise is on the United States Fish and Wildlife Service (USFWS) list of endangered species and requires a Captive-Bred Wildlife (CBW) permit. To purchase a Galapagos tortoise from out-of-state requires that both parties have a valid CBW and submit an annual report to the USFWS. The Aldabra tortoise is not regulated by the USFWS, and they are still imported in limited numbers to the United States.
Another difference of the two species is personality. Most tortoise species when frightened or scared will pull their head and front legs into their shell.
Galapagos tortoise are a very friendly species and will quickly learn to trust their owner and will stand high on all four legs and stretch their head up high to allow you to scratch their neck. Young Aldabra tortoises, however, are much more wary and seem to have a flight response. They will generally run for cover if scared or frightened. Though running for cover seems like a strange behavior for a tortoise, they will gradually calm down and exhibit similar behavior to the Galapagos tortoise and stretch their heads out and allow them to be scratched. Though the Aldabra tortoise may take a little more work to tame than a Galapagos tortoise, both can be very personable and friendly.
Jerry D. Fife lives in Phoenix, Ariz., and has written a number of books and articles. He has traveled to the Galapagos Islands to see these tortoises in the wild, and he maintains and breeds a number of tortoise and lizard species. His books include: Iguanas, A Pictorial Guide to Iguanas of the World and Their Care in Captivity; Leopard Tortoises: The Natural History, Captive Care and Breeding of Stigmochelys pardalis (with his brother, Richard Fife); Star Tortoises: The Natural History, Captive Care, and Breeding of Geochelone elegans and Geochelone platynota; and soon to be released, Mediterranean Tortoises: The Natural History, Captive Care and Breeding of Greek, Hermann's, Marginated, Russian, and Egyptian Tortoises. To contact him, visit his website at fifereptiles.com.