Galapagos giant tortoises are icons of the natural world. They're famous for their diversity, which inspired a young Charles Darwin during his voyage around the world, and for their longevity, which has curious scientists seeking the secrets of the reptiles' long lives. Now, a tortoise named Diego is gaining fame for a very different reason: his incredible sex life.
Along with their many positive claims to fame, Galapagos tortoises are also, unfortunately, among the world's most famous endangered species. A few centuries ago, there were hundreds of thousands of these lethargic reptiles living throughout their home islands, with as many as 15 species. But humans hunted them for meat and oil, and introduced harmful invasive pests such as rats and pigs to the islands. Today, fewer than 30,000 tortoises remain, and up to four of the species are thought to be completely extinct.
Diego is an Española giant tortoise (Chelonoidis hoodensis), and his species very nearly became extinct as well. Several decades ago, conservationists discovered that only a dozen females and two males still survived on the island of Española – and they weren't reproducing. The animals were rounded up and transported to a captive-breeding programme in the hopes of repopulating the island. As luck would have it, a third male was later found living in the San Diego Zoo ... enter Diego.
"We don't know exactly how or when he arrived in the United States. He must have been taken from Española sometime between 1900 and 1959 by a scientific expedition," said Washington Tapia, a tortoise preservation specialist at Galapagos National Park. Diego was brought to the breeding centre on Santa Cruz Island in 1976.
At over 100 years of age and weighing 80kg (175lbs), Diego is a fine specimen, the largest of the three males at the start of the breeding programme. The lucky guy shares his enclosure with six females, and for years, he's been doing his due diligence – eagerly, I’m sure. But it was only recently that scientists realised just how successful he has been.
The breeding programme has produced and released about 2,000 newborn tortoises onto the island, an incredible improvement from the 15 they started with. The species has been spared the fate of some of its cousins, and a recent genetic study of the turtles found that about 800 of these new tortoises – roughly 40% of them – are Diego's offspring. This has been one busy tortoise!
According to the Galapagos Conservancy, female tortoises generally lay between one and four nests each breeding season, and the saddle-backed species like Diego can lay up to seven eggs per nest. To produce 800 babies, it's safe to say Diego is pretty spry for an old guy. His species is now happily spread across the island of Española, and he produced nearly half of them single-handedly (or single … you know, another organ).
The battle to save the species isn't over yet, though. "I wouldn't say [the species] is in perfect health, because historical records show there probably used to be more than 5,000 tortoises on the island," said Tapia. "But it's a population that's in pretty good shape – and growing, which is the most important." Presumably, as the breeding programme continues, the researchers will also work to improve the genetic diversity of the species.
It's encouraging to see these tortoises bouncing back from disaster, especially with the sad death of Lonesome George – the last of his own species – still fresh in our minds. With luck, and with enthusiastic participants like Diego, breeding programs of other tortoises will see similar success.
Top header image: Andrew Miller/Flickr