Giant tortoise makes 'miraculous' stable recovery
The study used records kept by national park staff, repeatedly marking, measuring and releasing tortoises
Where once there were 15, now more than 1,000 giant tortoises lumber around Espanola, one of the Galapagos Islands.
After 40 years' work reintroducing captive animals, a detailed study of the island's ecosystem has confirmed it has a stable, breeding population.
Numbers had dwindled drastically by the 1960s, but now the danger of extinction on Espanola appears to have passed.
Galapagos tortoises, of which there are 11 remaining subspecies, weigh up to 250kg and live longer than 100 years.
The study, based on decades of observations of the variety found on Espanola, was published in the journal Plos One.
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Slow release
It offers some good news that contrasts with the tale of Lonesome George, the very last of the related subspecies found on Pinta, on the other side of the archipelago. George's death, at the age of about 100, made international news in 2012.
Lead author Prof James Gibbs told BBC News the finding on Espanola was "one of those rare examples of a true conservation success story, where we've rescued something from the brink of extinction and now it's literally taking care of itself".
Prof Gibbs, from the College of Environmental Science and Forestry at the State University of New York (SUNY-ESF), said he felt "honoured" to be reporting the obvious success of the reintroduction programme, which the Galapagos Islands National Park Service commenced in 1973.