After 40 years of giving his all for a good cause, Diego the tortoise is heading into retirement. The giant tortoise, noted for his robust sex drive, is credited with fathering enough baby tortoises to bring his species back from the brink of extinction. 

Diego, who is more than 100 years old, helped boost his species' population from 15 to over 2,000 on Española, an Island that is part of the Galápagos. He had been shipped over from the San Diego Zoo as part of a breeding program, and was one of 15 tortoises to take part in the program at the Fausto Llerena Tortoise Center on the island of Santa Cruz. Now he'll finally be returning to his island of origin.

The Galápagos National Park announced on Friday that the decision was made to end the breeding program after 40 years, saying an evaluation showed it had met its conservation goals.

According to the statement, Diego "has become a symbol of the Galapagos conservation as it is estimated that approximately 40% of the turtles repatriated on Española Island are his descendants." 

He's estimated to have about 1,700 offspring, according to the San Diego Zoo.

The closure of the Española tortoise captive breeding program will entail the return of the 15 unique breeding adults (12 females and three males) originally found on the island. 

"The conclusion was that the island has sufficient conditions to maintain the tortoise population, which will continue to grow normally — even without any new repatriation of juveniles," Washington Tapia, the Galápagos-based director of the Giant Tortoise Restoration Initiative, said.

Diego was brought to the U.S. between 1928 and 1933 but returned to his home in 1977 to join the breeding center after his species was declared critically endangered in the 1960s, according to the San Diego Zoo.

It's been nearly eight decades since Diego was extracted from his natural habitat. With his mission accomplished, he will now be released into the wilderness on the island where he was born.