Giant tortoises go home after saving their species

Meet Diego, a tortoise around 100 years old, who is somewhat of a hometown hero.

He's one of 15 giant tortoises credited with saving their entire species - in a conservation success story for the ages.

And now, Diego and his 14 companions are headed for the final leg of their journey back into the wild, after decades of breeding in captivity.

Renowned for his fertility, Diego alone has fathered some 800 of the 2,000 offspring born in the Galapagos Islands' tortoise repopulation program.

Galapagos National Park ranger Freddy Villalva explains.

"I've been here with Diego the tortoise for 17 years. We know that thanks to him we've been able to bring back a species that was on the brink of extinction. And, I think Diego's legacy is allowing us to move forward."

The Galapagos giant tortoise can live to be 200 years old and is better known as one of the species that helped Charles Darwin formulate his theory of evolution.

UNESCO declared their native Galapagos Islands a World Heritage Site in 1978.

And now, Galapagos National Park Director Danny Rueda says Diego will soon be able to wander in the wild again, 80 years after being taken from his birth site on Espanola Island.

"Without a doubt, this is a successful program since we were able to restore this population with only 15 individuals. We've now detected natural reproduction on Espanola island, which shows us that the program has been successful and that we can shut down the captive reproduction program."

Strapped on to the backs of park rangers, the nearly 400-pound tortoises were brought by boat to Espanola before being carried all the way toward the island's interior and released on Monday (June 15).

There, they will have plenty of cactus to chomp their way through and be monitored by GPS trackers set up by park rangers -- so they can keep checking in on their old friends.