There is hope for the Galapagos giant tortoise in the form of Diego, a giant tortoise whose sexual activities helped rebuild his species' population in the famed Galapagos archipelago.

Diego--who was found in San Diego Zoo, hence his name--is over 100 years old. But his old age did not stop the Galapagos giant tortoise from rebuilding his population and saving it from extinction.

Scientists have recently discovered that he has fathered almost 800 young tortoises, or 40 percent of the total population released on their native island of Española, the southernmost part in the Galapagos.

"He's a very sexually active male reproducer," said tortoise preservation specialist Washington Tapia, as per Phys.org. "He's contributed enormously to repopulating the island."

Despite his old age, Diego is still very active, as evidenced by the boom of his species, the Chelonoidis hoodensis, which is found only in the wild in Española island, one of the oldest in the archipelago.

The IUCN Red List puts Diego the Tortoise's species at critically endangered, but hopefully Diego can help change that.

Diego the Tortoise (and his partners) to save the day

Around half a century ago, there were only two males and 12 females of the Galapagos giant tortoise of their species on the island. Unfortunately, they were too far from each other to reproduce.

Enter Diego, who was returned to Española in 1976 to be part of a captive breeding program. To this day, Diego lives at a tortoise breeding center on Santa Cruz Island, with six assigned females to do the tough job of having sex to save their kind.

Weighing about 80 kilograms (175 pounds), Diego is nearly 90 centimeters (35 inches) long and 1.5 meters (five feet) tall if he stretches himself out.

No one is exactly certain how he arrived in the United States, but experts think Diego must have been part of a scientific expedition.

A genetic study revealed that Diego is the happy father of almost 40 percent of the 2,000 young Galapagos giant tortoises released into the wild on the island.

Tapia said the population is in pretty good shape and continues to grow. "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," he said.

Three of 15 species of Galapagos giant tortoises have gone extinct due to pirates who plundered the Galapagos Islands.

Conservationists are happy for Diego's sexual exploits, as other attempts have not been successful. The last known survivor of the Chelonodis abingdoni, named Lonesome George, refused to breed in captivity until his death in 2012.