He may be well over 100 years old, but Diego the Tortoise still has plenty of charm and he's using it to ensure that his species lives on.

The giant Galapagos tortoise has been "working" since the 1960s—when there were only 14 wild tortoises, two of which were male, left on Española—to save his native species from the brink of extinction. And he's doing an impressive job.

Based on recent genetic studies, Diego has single-handedly fathered an estimated 800 offspring—40 percent of the 2,000 captive-bred tortoises that have since been released into the wild.

"He's a very sexually active male reproducer. He's contributed enormously to repopulating the island," tortoise preservation specialist, Washington Tapia, from the Galapagos National Park, told the AFP.

Scientists say Diego is the dominant male of the three assigned to repopulate the island, and weighs about 175 pounds, is nearly 35 inches long and 5 feet tall.

While most of Diego's history remains a mystery, scientists do know he was discovered at the San Diego Zoo in the 1950s. After being located at the zoo, Diego was brought back to the Galapagos in 1976 and put in the captive breeding program, AFP reported. He currently lives at a tortoise breeding center on Santa Cruz Island in the Galapagos, where he and six females share an enclosure.