Biodiversity, Environment, Headlines, Latin America & the Caribbean, Tierramerica

GALÁPAGOS: The Return of the Giant Tortoise

Gonzalo Ortiz* - Tierramérica

QUITO, Jul 7 2010 (IPS) - The historic reintroduction of giant tortoises is under way on Pinta Island, where not a single one of the famous animals that gave their name to the Ecuadorian archipelago of Galápagos remained.

“The tortoises have adapted well to their new habitat and are moving in a radius of approximately 1.5 kilometres from the site where they were released,” said biologist Washington Tapia, of Galápagos National Park, head of the experiment on Pinta Island, which has an area of 60 square km.

The expert explained in an e-mail interview with Tierramérica that a group of students working on the site is recording the movement of the reptiles, their activities, data on environmental conditions and the animals’ impacts on vegetation and the ecosystem in general.

To do so, they are using satellite monitoring, through the global positioning system (GPS), and VHF radio waves. They are also posting brief reports on their experiences on a blog.

Ecuador’s Ministry of Environment is supervising the whole plan.

Involved in the release of the tortoises was a team of park rangers, biologists, herpetologists, botanists and veterinarians from Galápagos National Park, the Houston Zoo (based in the U.S. state of Texas) and State University of New York’s College of Environmental Science and Forestry.

Tapia stressed that it is a “long-term and costly project, which began 30 years ago when the National Park began to eliminate the goats,” an “invasive species” that had been introduced to the islands and quickly proliferated, numbering in the tens of thousands.

For just the past two years, with the selection and preparation of the tortoises for their release, “including the students’ stay on the island until late July,” their supplies and logistics, the cost “reaches approximately 350,000 dollars,” he said.

The operation is financed by the non-governmental Galápagos Conservancy, whose members donate money for a variety projects in the archipelago, and by private companies and the Ecuadorian government.

LONESOME GEORGE

When young Charles Darwin (1809-1882) visited the Galápagos in 1835, he noticed the unique bills of the bird species, and the differences amongst the tortoises, depending on what food was available on each island, which planted the seeds of what would become his theory of evolution through natural selection.

The tortoises — which are land animals, unlike their turtle cousins — vary in the structure and length of the neck and feet, and the shape of their shells. The body, over the course of thousands of years, has adapted to whether they are eating vegetation on the ground or from low branches of cactus.

When pirates and whalers of the 18th and 19th centuries began to kill the tortoises to extract their oil and to bring the animals on board as food reserves, the survival of some species turned critical.

The devastation was such that by the early 20th century there were no tortoises left on Pinta, one of the northeastern uninhabited islands of the Galápagos, which are located in the Pacific Ocean, about 1,000 km from the South American coast. According to the biologists, two centuries ago there were 5,000 to 10,000 on Pinta Island alone.

To everyone’s surprise, in 1971 a male tortoise was discovered alive on Pinta, although he was not doing well, having to compete for food with the goats, whose numbers reached 40,000 after just three goats were illegally left on the island in 1951.

The tortoise was rescued and taken to a biological station of the non- governmental Charles Darwin Foundation on the neighbouring island of Santa Cruz.

The giant “Geochelone elephantopus abingdoni” known as Lonesome George because no female of his species has been found, is now one of the attractions for visiting biologists and tourists.

TIME FOR RESTORATION

The Charles Darwin Foundation began raising endangered tortoise species in captivity in 1965, and in the 1970s joined forces with the Galápagos National Park to get rid of invasive species — goats in particular.

They were able to remove the goats from nearly all the islands, completing the task on Pinta in 2003. “The wild goats have been exterminated so that the Galápagos Islands don’t die,” Sylvia Harcourt Carrasco, board member of the Foundation, explained in response to Tierramérica’s questioning.

The feeding habits of the otherwise inoffensive invasive species like goats, donkeys, dogs and cats threaten the fragile ecosystem of the archipelago, which UNESCO (United Nations Educational, Scientific and Cultural Organisation) declared a natural heritage of humanity site in 1978.

Once the goats were gone, the vegetation on Pinta quickly recovered. The next step, for a complete and balanced restoration, was the return of the giant tortoises.

Enter the hybrid species that the Galápagos National Park maintained in corrals, in some cases for as long as 40 years. Instead of keeping them in captivity for decades longer — these tortoises can live more than 150 years – – it was decided that 39 of them would be the new colonisers of Pinta.

For the eight months before their release, the health and diet of the 39 were closely monitored. They were vaccinated, measured and cleared of parasites. Most weigh more than 90 kilograms, and some reach 200 kilos.

In addition, they were sterilised, “because it isn’t appropriate that they reproduce, being the product themselves of crosses that don’t belong to the original tortoise subspecies” of the Galápagos, explained Tapia.

The new colonists, transported by boat, arrived on Pinta on May 19. Park rangers, who had been quarantined and used sterilised clothing, transferred the tortoises to a mid-altitude area with abundant vegetation, where they were released.

Tapia said that because they are adults, the released tortoises probably consume several kilos of plants per day.

“With that consumption and their movements they are expected to mould the ecosystem to create open spaces, which will permit the development of other ecological processes, such as nesting by birds, reproduction of invertebrates and seed dispersal,” he said.

“That is what is happening, successfully, on Española Island, where tortoises were reintroduced in previous years,” Harcourt-Carrasco said.

After rigorous planning and monitoring, the idea is to populate Pinta with tortoises from Española that are capable of reproduction, as they are the closest genetically to Lonesome George. But it is not yet known of the solitary tortoise will return to his home island.

(*This story was originally published by Latin American newspapers that are part of the Tierramérica network. Tierramérica is a specialised news service produced by IPS with the backing of the United Nations Development Programme, United Nations Environment Programme and the World Bank.)