Giant Galapagos tortoises used to be a symbol for endangered animals. A project aimed at restoring these reptiles has changed the face of an island in the Pacific.
At the Brink of Extinction
During the late 19th century, the ecology of the Galapagos Islands was changed by pirates, settlers, and whalers. These people poached some native species in the area, such as the Galapagos giant tortoises, and introduced other species, such as goats and rats.
Later on, rats became pests, which severely destabilized the island ecosystems. The goats overgrazed the fruits and plants that served as food for the tortoises, while the rats preyed on their eggs. As a result, the tortoise population quickly declined. On the Española island, the tortoises fell from more than 10,000 to just 14. As the goats ate all the plants they could, Española, which once resembled a savanna, turned into a barren land.
READ ALSO : Giant Tortoise Still Roams Galapagos Islands After Being Thought to be Extinct 100 Years Ago
Efforts to Restore the Tortoise Population
After a century, conservationists set out to restore the Galapagos giant tortoise on Española and the island ecosystem. They started with eradicating introduced species and capturing Española's remaining tortoises to be bred in captivity.
The ecosystem transformed once again since the goats were wiped out and the tortoises were in cages. This time, the barren terrain became overgrown with densely packed trees and woody bushes. The island's full recovery to its savanna-like state would have to wait for the return of the tortoises.
Between 1963 and 1974, the 14 tortoises were taken into captivity until they were finally released in 2020. In collaboration with the NGO Galapagos Conservancy and the Galapagos National Park Directorate, conservationists reintroduced almost 2,000 captive-bred giant tortoises to Española.
Since then, the reptiles have continued to breed in the wild, causing the population to rise to an estimated 3,000. Experts have also seen the transformation of the ecology of Española as the tortoises reduce the extent of woody plants, which led to the expansion of the grasslands.
The return of the tortoises also helped the waved albatross from being critically endangered. During the woody era of the island, people had to repeatedly clear the areas used by the seabirds as runways to take off and land. As the landing strips are overgrown, they plan to move tortoises into the room to take care of it for them.
The secret to this success is the ability of the giant tortoises to be ecological architects, just like elephants, brown bears, and beavers. These reptiles alter the landscape as they browse, poop, and plod about, trampling young trees and bushes before they can grow big enough to block the way of the seabirds.
Conservation scientist James Gibbs documents the extent of the ecological effects of the tortoise. In a new study, he and his team investigated the evolution of the landscapes when they are either exposed to or free from the influences of the tortoises. They also studied the satellite imagery of the island taken between 2006 and 2020. They discovered that while some regions of the island have increased the density of trees and bushes, the areas where the tortoises have reintroduced are more open and savanna-like.
However, conservationists still have a lot of work to do. In 2020, 78% of the island was still dominated by woody vegetation. Experts say it may take another couple of centuries before the giant tortoises reestablished something like the ratio of grasses, trees, and bushes before Europeans arrived in the archipelago.
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