A giant tortoise subspecies that once teetered on the brink of extinction has made a big comeback on its Galapagos island home.

In the 1960s only 15 of the tortoises, which can weigh over 225 kilos, remained on the island of Espanola. They came close to being wiped out by ecological damage caused by feral goats introduced in the late 19th century.

Today, 40 years after captive-bred tortoises were reintroduced to the island by the Galapagos National Park Service, their numbers have grown to around 1,000 and they are breeding.

US conservation expert James Gibbs, from the Suny College of Environmental Science and Forestry in New York, said: “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 led a team of researchers that assessed the tortoise’s progress using four decades of recorded data on the animals.

This is a miraculous conservation success

He stressed that while the tortoise population is stable, more of the island’s landscape still has to recover from the damage inflicted by the now-departed goats.

“Population restoration is one thing, but ecological restoration is going to take a lot longer,” said Gibbs, whose findings appear in the online journal Public Library of Science One.

Shrubs and small trees have grown to replace the grassy vegetation devoured by the goats. This hinders the giant tortoise’s movement and the growth of cactus, a vital part of its diet.

Chemical analysis of the soil on Espanola shows a pronounced shift from grasses to woody plants in the last 100 years.

The shrubs and trees have also adversely affected the endangered waved albatross that breeds on the island, making it difficult for the ungainly sea birds to take flight.

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

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