The giant tortoises of the Galapagos Island were on the brink of extinction just a half-century ago, but 40 years after several specimens of the endangered species were bred in captivity and released back onto the island of Española, the massive land-dwelling turtle is once again thriving.

"The global population was down to just 15 tortoises by the 1960s," James P. Gibbs, a biologist at the State University of New York College of Environmental Science and Forestry, explained in a recent press release. "Now there are some 1,000 tortoises breeding on their own. The population is secure. It's a rare example of how biologists and managers can collaborate to recover a species from the brink of extinction."

Gibbs and his colleagues have been charting the growing success of the island's tortoises and recently outlined their rebound in a paper published in the journal PLOS ONE.

Now thriving, in large thanks to the hard work of local biologists and wildlife managers, the tortoises are doing a bit of their own ecological restoration -- scattering the seeds of the island's native cacti. Only a few decades ago, the plant was near nonexistent, wiped out by feral goats that were introduced to Española towards the end of the 19th century.

Despite the good news, the tortoise remains vulnerable and is still listed as endangered; researchers say managers must be diligent to keep the turtle population on the right track.

"This is a miraculous conservation success accomplished by the Galapagos National Park Service," said Gibbs, "but there is yet more work to fully recover the ecosystem upon which the tortoises and other rare species depend."