It’s not often that we can credit one individual with almost single-handedly saving their entire species. These stories certainly fill us with hope that dedicated people are making such fantastic progress towards restoring endangered wildlife. However, they also tell a depressing tale of how their numbers became so critically low that all hopes of survival rested on just a handful of individuals. This was the case for Diego, the tortoise who saved his species.

Diego is a Hood Island giant tortoise (Chelonoidis hoodensis), which is a type of Galápagos tortoise found only on the island of Española in the Galápagos archipelago. These tortoises went down to just 15 individuals before conservationists launched a captive breeding programme in an attempt to save the species from extinction.

Diego has been part of this breeding programme for more than 40 years and has fathered over 800 offspring during that time.

Española Island. Photo by David Broad

The Story of Diego

Diego was born on Española in the early 1900s – the exact date is unknown. At this time, the Hood Island giant tortoises were already suffering from exploitation by mariners throughout the 1800s. 

In the 1930s, a team of researchers captured Diego and took him to the United States. He was exhibited in zoos for many years, eventually ending up at the San Diego Zoo in California.

He remained here for 30 years being admired by the hordes of visitors that came through the attraction each year.

By the 1970s, the Española tortoises were in a critical state. An extensive search of Española found only 14 tortoises – 2 males and 12 females – and because the island was 23 square miles, they were rarely coming into contact to mate. Local authorities decided they urgently needed to run a captive breeding programme to prevent these unique tortoises from disappearing entirely. 

But with so few tortoises, the team knew that they needed to cast their net out further to try and find more, in particular males. So they began a worldwide search in the hopes of finding another Hood Island giant tortoises in captivity somewhere. 

At this time, it was unclear which species of Galápagos tortoise Diego was. However, DNA testing soon revealed him to be the species they were searching for. He travelled back to Galápagos in 1976 where he joined the captive breeding programme on the island of Santa Cruz.

The breeding programme lasted more than 40 years and produced over 2,000 tortoises, of which Diego has fathered around 40% of them.

The islands of Santa Cruz and Española in the Galapagos Archipelago.

Journey Home

At the beginning of this year, officials announced they were closing the captive breeding programme. The efforts to restore tortoises on the island has reached a point where the population is continuing to grow naturally.

In June, Diego, now over 100 years old, returned to his native island of Española, more than eight decades after he left. Here he will live out the rest of his days in retirement alongside the other tortoises from the breeding programme.

Thanks to this programme, around 2,300 tortoises are now reproducing naturally on the island.

All 15 tortoises set out from Santa Cruz on a 5-hour journey by boat to Española. Rangers then strapped them onto their backs and carried them for 2.5km to a place called Las Tunas. Las Tunas is rich in Opuntia cacti, the primary food source for the tortoises. 

A satellite device has been fitted to all tortoises to track their position. Alongside the 40 camera traps in the area, this will enable the team to observe their behaviour in the wild.

The Galápagos Islands are famed all around the world for their rich biodiversity. Since Charles Darwin’s famed visit to the islands in 1835, human presence had continued to threaten the island’s wildlife. 

Programmes like this one are helping to restore species and preserve the beauty of these globally important islands.


References

Galápagos Conservancy – Española Tortoises Return Home Following Closure of Successful Breeding Program

Header image credit – Diego, a Hood Island Giant Tortoise (Chelonoidis hoodensis) at the Charles Darwin Research Station in Santa Cruz, Galapagos. Author: Kaldari. Creative Commons CC0 1.0. Image.


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