These tortoises saved their species from extinction. Now they're back home

Diego, a tortoise of the endangered Chelonoidis hoodensis subspecies from Española Island, is seen in a breeding centre at the Galapagos National Park on Santa Cruz Island in the Galapagos archipelago, located some 1,000 km off Ecuador's coast, on September 10, 2016.

Island life is treating 15 recently released giant tortoises well as they settle back into their home island after decades in a captive breeding program.

The tortoises, 12 female and three male, have been busy saving their species from extinction. Now they're slowly getting back to their roots on Española Island in the Galapagos, commingling with more than 2,300 descendants stemming from the program.

Representatives from the Galapagos National Park Directorate and Galapagos Conservancy returned the 15 tortoises to their home island on June 15. Each tortoise was outfitted with a GPS satellite device so the researchers could track their movements each day.

Washington Tapia, director of the Giant Tortoise Restoration Initiative through Galapagos Conservancy, has been tracking their whereabouts since they returned to the wild.

"It's amazing because all of them are in the same place," Tapia says. "Two females moved around one mile from the (original) place."

Tapia says tortoises tend to move when they need to find food and since they dropped them off in a location with a large food source -- Opuntia cacti -- they won't need to move for nearly a month.

When they do move, Tapia says he is interested to see how the male tortoises will interact with the younger male tortoises they reintroduced to the island over the past decades.

One returning giant tortoise, named Diego, contributed to approximately 40% of the offspring repatriated to the island. His return came nearly 80 years after he was removed.

For the past 55 years of the program, which is located on Santa Cruz Island, the hatchlings were transferred to Española at around five years old. Over the years, the breeding program reintroduced 1,900 tortoises into the wild. Today, there are over 2,300 tortoises due to the natural reproduction occurring on the island.

The returning females weigh an average of 77 pounds and the males weigh close to 120 pounds.

While the final transfer of the giant tortoises happened in mid-June, it was originally supposed to occur in March. The trip had to be pushed out three months due to the pandemic.

Prior to the transfer, Tapia said the tortoises had to undergo two months of quarantine -- but not because of the coronavirus.

The food that the tortoises eat leaves seeds in their digestive system. It's a great way to keep the ecosystem thriving, according to Tapia, but it can also introduce foreign plants to the island.

Once the quarantine was over, Tapia led the team that transferred the tortoises to their final home. It was a bittersweet moment for Tapia, who had worked closely with the tortoises over the years.

"It's like when you send your children to university," Tapia says. "You are happy but at the same time you are sad."

The tortoises were transferred at the end of the rainy season, which was the last possible moment they could've been moved, according to Tapia. When the dry season kicks in, it's harder for the tortoises to find food.

If they couldn't make the transfer in June, Tapia said they would've had to delay the transfer by a year.

In six months, a team will visit Española to see how the tortoises are adjusting.

In addition to the GPS devices on the animals, researchers also placed 40 motion-triggered cameras around the island. Unlike the GPS data, they are unable to access the cameras until they visit the island.

Tapia has worked with the tortoises for years and said he is excited to look at the camera footage and see how they adapt to their new home.

Created in the mid-1960s, the Española program is among the world's most successful captive reproduction and breeding programs.

The tortoises' return to the island marks the program's official end.