PARTNERS: Galapagos National Park and Research Foundation of SUNY STATUS: Phases I and II are Complete; Phase III , Introducing tortoises capable of reproduction to the island (TBD)
The ecological restoration of Pinta Island through the reintroduction of giant tortoises is a high conservation priority for Galapagos. This project focused on introduction of 39 non-reproductive adult tortoises in May 2010 as “Project Pinta” to catalyze a more balanced restoration of the Pinta ecosystem. The post-release monitoring project during Phase I focused on tortoise movements, food habits, and impact on the ecosystem. With the deployment of movement monitoring devices on the tortoises, they were able to observe the tortoises’ behavior and use of the habitat. These observations, along with plant community measurements, provided the components necessary to address the goals of Project Pinta.
The continuation of the project to Phase II involved a revisit to Pinta in May 2011 to monitor changes in tortoise behavior and ecosystem impacts since introduction. Together the Phase I and II research will permit development of recommendations for the long-term management of Pinta in relation to: (1) the likely carrying capacity of tortoises on Pinta and best strategies for future introductions (e.g., preferred habitats, numbers, and seasons for release) and (2) how tortoises are likely to alter habitats on Pinta and, particularly, whether an introduced tortoise population can reverse woody plant succession and over what time frame. As such, the information gathered from the proposed monitoring program will support development of a recovery plan for the island’s ecosystem through the eventual release of a reproductive tortoise population genetically related to the Pinta tortoise species, now extinct in the wild.
SUNY-ESF's Hunter with Wilman (tortoise) during Phase 2 of Project Pinta. (Photo: Claire Phillips)
Elizabeth Hunter returned to Pinta Island in May 2011 with two primary research objectives:
Determine how tortoises interact with the plant community to enable prediction of how tortoise habitat preferences may impact the plant community over time.
Suggest guidelines for future introductions of reproductive tortoises including introduction sites and best release strategies.
The field research focused on the following components:
Environmental drivers of tortoise movements
Tortoise effects on plant community
Cactus population size and density
Tortoise impacts on other aspects of the ecosystem
Sea lion population size (done at request of the GNP)
Recommendations for future management by the GNP include:
Because domed tortoises preferentially use higher, moister zones of Pinta Island which are extremely restricted on the island, domed tortoises do not seem appropriate for further release on Pinta. Of the saddle-backed individuals, there was little variation in behavior and habitat preferences, despite different genetic origins among individuals. This argues that saddle-backed tortoises from Espanola could serve as well as any other analog saddle-backed tortoises for introduction to Pinta.
The best introduction zone for cactus resources is in the pampas, but the current introduction point has a much higher density of trails due to high tortoise use. Trails could be important for future juvenile tortoises’ mobility in the dense vegetation on Pinta, and it is also likely that many of these adult tortoises will stay in this zone creating trails. Depending on expert knowledge about the relative importance of food resources versus functional trails to young tortoises, the GNP could put groups of tortoises in either or both locations. The key issue is to establish multiple sites of released animals in cactus-rich areas so that tortoises will be able to find other tortoises upon reaching sexual maturity but not compete heavily for food resources during their early years of development.
The high weight gain of the tortoises one year after release indicates that food resources are abundant and further introductions can likely be supported by the environment.
Based on our analysis of the mark-recapture data from Española, introduction of 5-year-old juvenile tortoises (and not younger) is best in terms of survival. Introduction of adult reproductives does not increase initial population growth substantially more than juvenile-only introductions, and so is not recommended.
To fully understand the impact that tortoises have on the plant community, we recommend erection of tortoise exclosures before future releases that would prohibit tortoise disturbance, herbivory, and seed dispersal in areas of high tortoise impact near release sites. This will allow a direct comparison of tortoise areas and non-tortoise areas to greatly clarify our understanding of tortoise impacts on ecosystems. Clarifying these impacts is important for articulating the role tortoises play as ecosystem engineers in Galapagos and hence, as appropriate, building support for archipelago-wide restoration efforts
The third phase of Project Pinta will involve repopulating the island with a reproductive population of tortoises. The 2012 discovery of Pinta Tortoise Hybrids on Wolf Volcano on Isabela Island has added a new, but welcome, complication to this Phase of the project. Decisions will be made in the coming months as to whether the islands will be repopulated with young saddle-backed tortoises from another Galapagos tortoise species, or if the future offspring of cross-bred Pinta hybrids will repopulate the island several years down the line.
Video from Project Pinta
Produced by a team of graduate students from American University, the video below features an interview with GC’s Science Advisor, Linda Cayot as she discusses the importance of this historic conservation achievement and provides a glimpse behind the scenes of the tortoise captive breeding program at the CDRS.
The short video below provides more extensive footage of the journey, as the 39 tortoises made their way out of captivity on Santa Cruz Island to the wild highlands of Pinta Island.
Dr. Joe Flanagan and Dr. James Gibbs (left) conduct a health assessment of one of the tortoises headed to Pinta. Elizabeth Hunter and her team (right) remained on Pinta for 2.5 months to monitor the tortoises. Photos courtesy of Francisco Laso.
Background on Recent Conservation Efforts
Pinta Island, one of the northernmost islands in the Galapagos Archipelago, is a symbol of both the potential destructive impact of humans on fragile ecosystems, as well as our growing capacity to achieve complete ecological restoration of degraded areas.
After almost 200 years of ecological decline, caused first by whalers who decimated Pinta’s giant tortoise population, and then by introduced goats, which devoured its native and endemic vegetation, scientists and conservationists are prepared to return the 60 sq. mile island to near pre-human condition.
This achievement, which will involve the repopulation of Pinta with giant tortoises, would not have been possible without technologies and conservation tools developed in Galapagos over the last 40 years, some of which were only recently refined.
Centuries of Destruction
Pinta Island has long been home to swallow-tailed gulls, marine iguanas, Galapagos hawks, fur seals and a number of other unique bird, mammal and plant species. Until the mid 19th century, it was also home to thousands of Pinta Tortoises—giant saddleback tortoises endemic to this island.
During the 1800s, whalers removed large numbers of Pinta tortoises as a food source on their long journeys. By the early 20th century, the Pinta tortoise was likely ecologically extinct, although there is evidence of fishermen slaughtering tortoises through the mid 1900s. The sole known surviving Pinta tortoise, Lonesome George, was taken into captivity in 1972; no other live tortoise has been found since. For nearly 40 years, Lonesome George has remained in captivity and Pinta has been without tortoises.
With tortoises gone, fishermen introduced goats to Pinta in 1959 to ensure a source of food during their seasonal trips to northern waters. During the 1960s and 1970s the goat population exploded to over 40,000 causing massive destruction of Pinta’s vegetation. In the early 1970s, the Charles Darwin Foundation and Galapagos National Park staff began efforts to eliminate goats from Pinta and reduced the population to fewer than 100 individuals. However those goats remained in the rugged cliffs of Pinta where existing eradication methods were not effective.
The turning point for Pinta came in 1999 when the island was used as a training ground for new methods of goat eradication that would later be put to use on a much larger scale on Isabela and Santiago Islands. After almost three decades of unsuccessful eradication attempts, the implementation of judas goat techniques (which involve the use of radio-collared goats to help locate the last remaining feral goats), aerial hunting, and improved mapping and data management systems (GPS and GIS systems) quickly eliminated goats from Pinta.
Fortunately, it appears that the intense grazing pressure by goats was stopped before any of Pinta’s plant species went extinct. Moreover, an intensive coast-to-summit monitoring project carried out in 2000 and repeated in 2004 shows that vegetation recovered rapidly in the absence of goats.
There are indications, however, that some of the endemic plant species that require substantial light, such as the Darwin Aster, Galapagos Cotton, Galapagos Snapdragon, and Galapagos Passionflower, could be negatively affected by the unchecked regeneration of Pinta’s vegetation. There is also concern that some species may decline due to the absence of large-seed dispersers. Prior to their elimination, Pinta tortoises played an important role in the dynamics of the ecosystem, through herbivory, seed dispersal, and trampling and opening of small areas.
Restoring Ecological Balance
For many years, conservation in Galapagos was focused on “population-based objectives.” In the case of Pinta, this meant looking for ways to save the Pinta Tortoise. While such an approach is still considered important when possible, conservation managers in Galapagos also understand that the conservation of biodiversity and evolutionary and ecological processes in the archipelago requires a broader vision, focused on the protection and restoration of islands and ecosystems.
Many botanists and herpetologists have pointed to the importance of re-establishing a tortoise population on Pinta. However, there has been considerable debate regarding how this should be accomplished. Those embracing a population-based approach have insisted that only Pinta tortoises should be used for this purpose. But given that short- and medium-term options for developing a Pinta tortoise population are considered unrealistic, a growing number of experts have called for the use of a carefully selected relative—or analog species—to repopulate Pinta.
In May of 2010, 39 sterilized hybrid adult tortoises were transferred to Pinta Island to begin their important job of altering the landscape. These tortoises had been living for decades in captivity under the auspices of the Galapagos National Park at the Tortoise Center in Santa Cruz and in a tortoise corral on Floreana. They will now live out their remaining decades in the wild. But the plans for tortoises on Pinta do not end here.
Currently genetic analyses of more than 1600 blood samples of tortoises found on Volcán Wolf are under way. This northernmost volcano of Isabela apparently harbors a mixture of tortoises from various islands due to historical activities of humans in the archipelago. Once these data are completed, it will be possible for the Galapagos National Park to make a final decision regarding Pinta. If no Pinta tortoises or a sufficient number of tortoises with some Pinta ancestry are found, Española tortoises will provide the best possible means of restoring balance to Pinta’s ecosystem by establishing a population of tortoises that are capable of reproducing (unlike the sterilized hybrids). The Española tortoise comprises the taxon most closely related to the Pinta tortoise. It is also currently available through the successful breeding and rearing program of the CDF and the GNPS.
Funding for Project Pinta
This project has been made possible by funding from the Galapagos National Park, and generous contributions of the Panaphil Foundation, Continental Airlines, Buffalo Exchange, SUNY-ESF, the Houston Zoo, a number of veterinarians who have donated their services, and Galapagos Conservancy’s loyal donors.