About 50 years ago, there were only two males and 12 females of Diego’s species alive on Espanola, and they were too spread out to reproduce.

Diego the giant Galapagos tortoise whose tireless efforts were credited with almost single-handedly saving his once-threatened species, was put out to pasture Monday on his native island after decades of breeding in captivity, Ecuador’s environment minister said.

Diego was shipped out from the Galapagos National Park’s breeding programme on Santa Cruz to remote an uninhabited Espanola.

“We are closing an important chapter” in the management of the park, said the minister Paulo Proano on Twitter, adding that 25 tortoises including the prolific Diego, “are going back home after decades of reproducing in captivity and saving their species from extinction.”

Espanola welcomed them “with open arms,” he said.

Before being taken back by boat to Espanola, the 100-year-old Diego and the other tortoises had to undergo a quarantine period to prevent them from carrying seeds from plants that were not native to the island.