The “Miraculous Recovery” of the Galapagos Tortoise
The dwindling numbers of the Galapagos tortoises have been something of great concern for conservationists for decades. But now, after 40 years of hard work, the Galapagos Island of Española now has a stable and breeding population of giant tortoises.
In the 1960s, tortoise numbers had fallen so dramatically that there were only 15 left – 12 females and three males. The creatures were so rare that they had trouble finding each other on the island, and the females hadn’t mated in so long that lichen and fungi were growing on their shells.
But a detailed study Española Island’s ecosystem, published in PLOS ONE, has confirmed that the danger of extinction appears to be a thing of the past. This is all thanks to a reintroduction programme started in 1973 by the Galapagos National Park Service.
Galapagos tortoises can weigh up to 250kg (40 stone) and live up to 170 years. And yet, there are only 11 subspecies left. The animals are important to their environment because they are what are called “ecosystem engineers”. This means that their way of life helps to make life possible for other species of animals as well, in the arid landscape of the Galapagos Islands.
For example, cacti provide food for various songbirds and reptiles, as well as the tortoises. The tortoises mainly eat the cacti’s pads and fruit, the seeds of which are then spread around the island through the animals’ droppings, growing into plants to feed the various creatures, and so on.
The 15 tortoises from Española were taken to an enclosure on another island where focus went on breeding the animals. Since then, more than 1,500 offspring have since been released onto Española, and these are breeding well enough for the population to be maintained unaided.
The study’s lead author was Professor James Gibbs, from the State University of New York’s College of Environment Science and Forestry, or SUNY-ESF. He described the programme as “a miraculous conservation success” resulting in around 1,000 tortoises on the island breeding on their own.
“The population is secure,” he said. “It is a rare example of how biologists and managers can collaborate to recover a species from the brink of extinction.”
His team found that more than half of the tortoises that had been released since the programme was started in the 1970s were still alive. He said that he felt honoured to be reporting the obvious success of the programme but that there was still work to be done.
But this work is more to do with the ecosystem of the island itself. Feral goats – introduced in the 1800s and since removed from the island – stripped the land of its undergrowth, resulting in bigger, woodier plants. These prove a hindrance for such creatures as an endangered albatross. The large, ungainly birds breed on the island, but struggle to take flight with the tree-like plants in the way.
“Population restoration is one thing, but ecological restoration is going to take a lot longer,” Professor Gibbs pointed out.
But it looks like the tortoise “ecosystem engineers” will be able to help with that. And when it comes to the no-longer-endangered animal… “It looks like we’re no longer needed,” the professor concluded. “The tortoises can take care of themselves.”