Diego, a 100-year-old tortoise from the Chelonoidis hoodensis species, was brought to the Galapagos Islands almost fifty years ago from the San Diego Zoo, to join a breeding in captivity program. Diego was entrusted with the responsibility of saving his species — at the time, it was only him and one other male, and 12 female giant Española tortoises. Over the years, Diego has been called the “sex machine,” the “patriarch” and an “enterprising male” that managed to single-handedly father 800 offspring, constituting 40% of the current Española tortoises on the island.

Now, after a hard half-century’s work, Diego is retiring, Ecuador’s environment minister, Paulo Proano Andrade, has announced. Diego and 15 other tortoises “are going back home after decades of reproducing in captivity and saving their species from extinction,” Andrade tweeted.

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Diego’s pivotal work, coupled with efforts to eradicate non-native species from the region and cultivate cactus that tortoises rely on, has heralded a long and healthy future for Diego’s children. “We developed mathematical models with different possible scenarios for the next 100 years and in all the conclusion was that the island has sufficient conditions to keep the tortoise population that will continue to grow normally, even without any new repatriation of juveniles,” Washington Tapia, director of the Giant Tortoise Restoration Initiative (GTRI), told The Guardian.

Now, with Diego’s retirement, the spotlight is upon his children to continue his legacy of hard work.