The giant tortoise (Chelonoidis spp.) was one of the most devastated of all Galapagos fauna. Humans first exploited giant tortoises as a food source. In later years, they were harvested for oil. Some introduced species (primarily rats, pigs, dogs, and the Solenopsisant) prey on tortoises (particularly eggs and young tortoises); others (goats and burros) damage or destroy tortoise habitat.
Tortoises are crucial for a healthy Galapagos ecosystem. Photo by Alex Hearn
A systematic review of the status of the tortoise populations initiated in 1959 revealed that only 11 of the 14 original populations remained and most of these were endangered if not already on the brink of extinction. Beyond the tragedy associated with the loss of these magnificent creatures, their reduced numbers have left many of the island ecosystems unbalanced because tortoises play an important role in the dynamics of ecosystems, through herbivory, seed dispersal, and trampling and opening of small areas.
In the 1960s, the Galapagos National Park Service (GNPS), the Charles Darwin Foundation (CDF) and international scientists began to address the critical state of tortoise populations in the Islands. Successes have included:
1965: The first tortoise eggs from Pinzón Island were brought to the Charles Darwin Research Station for incubation, hatching, and rearing to avoid predation by black rats. Over 550 tortoises have been repatriated to Pinzón since 1970.
1965–1974: All remaining tortoises (2 males and 12 females) were collected on Española Island and transferred to the Tortoise Breeding Center on Santa Cruz where they were joined by a male Española tortoise from the San Diego Zoo. Since 1975, over 1,750 offspring have been repatriated to Española. Approximately 20% of the existing population consists of tortoises hatched from natural nests of these repatriates.
1971: Lonesome George was first seen on Pinta Island in 1971, at a time when Pinta tortoises were thought to be extinct. He was relocated to the Tortoise Center on Santa Cruz in 1972 in the hopes of finding a female Pinta tortoise in Galapagos or one of the world’s zoos.
1997-2006: Project Isabela successfully removed all feral goats—a major threat to tortoise populations—from Pinta Island (5,940 ha), Santiago Island (58,465 ha), and the northern portion of Isabela Island (approximately 250,000 ha). Following Project Isabela, these techniques have been applied to southern Isabela, Floreana, and other islands with rapid success, nearly achieving a goat-free archipelago and further clearing the path to the recovery of tortoise populations throughout the archipelago.
2010: 38 years after Lonesome George was removed from Pinta, 39 non-reproductive tortoises were returned to the island as a first step towards re-establishing tortoises on that island to fill their role as ecosystem engineers.
2012: Giant Tortoise Workshop was held in the Galapagos Islands convening international scientists, park rangers, and other tortoise experts to review the current status of information and to develop a 10-year plan for The Tortoise Recovery Project.
The Giant Tortoise Recovery Project
Galapagos Conservancy, the GNPS, the CDF and collaborators around the world continue to work toward returning the uninhabited islands to near pristine conditions and ensuring the survival of the remarkable flora and fauna of the archipelago, especially its namesake – the Galapagos giant tortoise.
Recent advances in the eradication of introduced mammals and our understanding of tortoise ecology and genetics have created opportunities that would have been impossible to imagine even a few decades ago. With goats gone, tortoise populations can be re-established on Pinta and Floreana islands as well as other areas. Additionally, genetic studies conducted by researchers from Yale University have reported the discovery of 84 hybrid tortoises on Isabela with the genetic signature of the Floreana tortoise – extinct since the mid-1800s – and 17 hybrids tortoises with the genetic signature of the Pinta tortoise. These discoveries, and the potential of finding even more tortoises with Floreana or Pinta genes, will provide the foundation for initiating a breeding program to recreate both tortoises populations and establish breeding populations of tortoises closer to the originals on both Floreana and Pinta than we ever believed possible.
At the Tortoise Workshop, the next phase of the Giant Tortoise Recovery Project was planned in order to build on these evolving opportunities. Key goals include:
Restore tortoise populations, including those considered “extinct in the wild,” through a combination of in situ management; selective breeding, rearing, and repatriation; and/or where appropriate, repopulating with analog species
Evaluate habitat conditions and long-term impacts of introduced species and restore where necessary
Study the importance of cactus to tortoise population and initiate plans for cactus recovery where needed
Integrate the tortoise recovery work with the GNP’s eradication/control efforts aimed at those species that impact tortoise populations
Improve education/outreach in service of giant tortoise conservation through collaboration among GNP, CDF, and others
The scope of the project and the scientific and financial commitment necessary to achieve success requires a thorough review of current knowledge and the identification of key information gaps, project collaborators, and sources of funding. Several plans resulting from the workshops are currently being developed.
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