October 28, 2014
A study published today in PLOS ONE reported that efforts to reintroduce the endemic Española giant Galapagos tortoise (Chelonoidis hoodensis) have been successful. In the 1960s, the population of Española tortoises had declined to only 15 individuals. The tortoises were captured and bred in captivity, and in 1975 the first offspring were released back to the island.
Over the last nearly 40 years, nearly 2,000 have been repatriated to Española Island. According to the study, today approximately half of those tortoises survived and many are now breeding naturally on the island — and their population is considered stable, making the risk of future extinction low.
“This is a rare example of how biologists and managers can collaborate to recover a species from the brink of extinction,” said James P. Gibbs, professor of vertebrate conservation biology at the SUNY College of Environmental Science and Forestry and lead author of the paper.
Gibbs and his collaborators, including GC’s Science Advisor Dr. Linda Cayot and Galapagos-based director of the Giant Tortoise Restoration Initiative (GTRI), Wacho Tapia, assessed the tortoise population using 40 years of data from tortoises marked and recaptured repeatedly for measurement and monitoring by members of the Galapagos National Park Service, the Charles Darwin Foundation, and visiting scientists.
Despite the population stability among the Española tortoises, the study found that ecological resources for continued population growth are increasingly limited due to damage inflicted by feral goats that were brought to the island in the late 19th century. Although the goats were eradicated in 1978, its long-term impacts have created a habitat such that the tortoise population is not likely to increase until more of the landscape recovers.
“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.” Read the entire study, and learn more about how GC is working to restore tortoise habitats in Galapagos.