Endangered tortoises from the Galapagos island of Española have been making an impressive recovery.
These tortoises are helping to restore ecological damage caused by feral goats after some of the captive-bred species were reintroduced to the island by the Galapagos National Park Service, SUNY College of Environmental Science and Forestry reported.
"The global population was down to just 15 tortoises by the 1960s. 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," said James P. Gibbs, a professor of vertebrate conservation biology at the SUNY College of Environmental Science and Forestry (ESF) and lead author of the paper published in the journal PLOS ON.
To make their findings the researchers looked at 40-years-worth of data from tortoises that were marked and recaptured for monitoring purposes. They found the species' population is relatively stable, but didn't predict a large growth rate in the future because of ecological consequences left over from the goats' reign.
"Population restoration is one thing but ecological restoration is going to take a lot longer," Gibbs said.
Once the goats were removed from the island some of the damage they had caused, such as eating all the grass and shrubbery, was reversed. The regrowth of plant life in the region did have a downside, it hindered the growth of cactus that are a vital part of the tortoises' diet. A DNA analysis of the soil on the island shows a shift from grasses to woody plants over the past century.
"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."
