A 100-year-old giant Galapagos tortoise is believed to have saved his species from extinction due to his rampant sex life, having fathered 40% of the offspring born in the past 50 years.

Diego is a quiet giant, measuring about 90 cm long and 1.5 metres tall when he is fully stretched out. He weighs 80 kg. His species, Chelonoidis hoodensis, is found in the wild only on Espanola, the southernmost island in the Galapagos archipelago. Diego lives at a tortoise breeding centre on Santa Cruz Island, where he is one of three males participating to the task of repopulating Espanola. Despite his advanced age, he still has plenty of stamina and remains the dominant male of the group.

Diego the tortoise
Diego can stretch out to a height of 1.5m Tui De Roy/Getty Images

Fifty years ago, there were only two male and 12 female Chelonoidis hoodensis tortoises on Espanola, and they lived too far apart to meet and reproduce. Diego was brought from San Diego Zoo in California in 1977 to help repopulate the island; a first positive step for the species – even though scientists could have had no idea he would take his mission so seriously.

Alongside the other males at the breeding centre, he saved Chelonoidis hoodensis from extinction.

Diego the tortoise
Diego used to live in San Diego Zoo, in the US Rodrigo Buendia/Getty images

It is only six years ago that scientists conducting DNA tests realised that Diego was the father of around 40% of the giant tortoises born and released on Espanola since his arrival. Out of the 2,000 tortoises that have been born on the island, at least 800 are thought to come from Diego.

Diego's species was also released on the Galapagos Island of Santa Fe, in a bid to replace a genetically similar tortoise known as Chelonoidis spp that disappeared 150 years ago.