Mission accomplished for a group of 15 male giant tortoises credited with saving their species from extinction. The tortoises—part of a breeding program that began in the 1960s when there were just two males and 12 females left in the wild, per CNN—were returned to their home on the island of Espanola in the Galapagos Islands on Monday after fathering some 2,000 offspring. About 800 of those came from Diego, a 100-year-old tortoise with a "legendary libido," the BBC reports. Diego, thought to have been removed from the Galapagos in the early 20th century, spent 80 years in the San Diego Zoo before being moved to the island of Santa Cruz in the Galapagos to take part in the tortoise recovery program, which will now end.
"We can shut down the captive breeding program of this species because their natural behavior is effective," Danny Rueda, director of Galapagos National Park, tells Reuters. Ecuador's environment minister, Paulo Proano Andrade, says the heroes were welcomed to Espanola, their native island, "with open arms," per the Guardian. After a period of quarantine meant to prevent the tortoises from transporting any non-native plants or seeds to the uninhabited island, the animals, weighing up to 400 pounds, were transported by boat, then carried in special backpacks to an area with an abundance of cactus, which should help them adjust to life in the wild. They'll be monitored for the time being with GPS trackers. (Read more Galapagos Islands stories.)