Meet Diego, a giant Galapagos tortoise, who's over 100 years old.

Well-known for his exceptional sex drive, Diego fathered an estimated 800 giant tortoises and saved his species.

The end of a successful breeding program

New York Times (NYT) reported that the hunting of the giant tortoises for meat by pirates, fishermen and whalers in the 1800s resulted in only 14 giant tortoises left in on Española Island.

Española Island is situated in the Pacific Ocean.

Today, there are close to 2,000 giant tortoises on Española Island.

This is thanks to the combined efforts by the Galapagos National Park and Galapagos Conservancy, a non-profit that protects the natural environments in the Galapagos islands.

In addition to a captive breeding programme, conservationists also worked on restoring the natural habitats of Espanola Island by growing cactuses, which is a food source for the tortoises.

The charismatic star of the program: Diego

Diego was among the 14 male tortoises selected to take part in the breeding programme, according to BBC.

NYT quoted the director of the Galapagos National Park, saying it is believed that Diego was most likely taken from Española Island in the 1930s.

After living at the San Diego Zoo for 30 years, Diego was recruited to join the captive breeding program at the Fausto Llerena Tortoise Center in 1976.

Following the success of the breeding program, Diego will be returned to the wild in March this year, BBC reported.

Nice tortoises don't finish last

According to this Facebook post by the Galapagos National Park, the breeding program has come to an end after proving to be successful in repopulating the giant tortoise population.

But even though Diego has captured the attention of international media, another male tortoise has fathered more tortoises.

Compared to Diego, female tortoises apparently preferred another quieter male, who fathered about 1,200 tortoises.

Diego, however, was known to be vocal and aggressive during mating.

Professor James P. Gibbs told NYT that giant tortoises form 'relationships' and have social structures that are not well-known.

You can check out the full Facebook post here:

Top photos by Parque Nacional Galápagos/Facebook