Pinzón Island (also called Duncan Island) is approximately 4,500 acres (1,800 ha), with a maximum altitude of 1,503 feet (458 m), and marks the geographical center of the Galápagos Archipelago.
Plaza Sur Island is small (30 acres/12 ha) but biologically significant. Both islands are uninhabited and are fully within the Galápagos National Park. Access is restricted to researchers and National Park staff.
RESTORING PINZÓN AND PLAZA SUR ISLANDS
inzón Island is home to one of the greatest species recovery stories ever told. More than 150 years ago, rats invaded the island and began feeding on the eggs and hatchlings of the island-endemic Pinzón Giant Tortoise. Due to invasive rats, tortoises were no longer able to survive past their hatchling phase, if they even hatched at all before being consumed. So, in 1965, conservationists, determined to save the tortoise initiated a captive rearing program aimed at getting tortoises past this critical life stage.
In December 2012, our conservation partnership completed a bold project to remove invasive rodents from Pinzón and Plaza Sur Islands, thus eliminating the primary invasive species threat to the tortoise and both islands’ at-risk species. In July 2013, heralding an important step in Pinzón tortoise recovery, hatchlings emerged from native Pinzón tortoise nests on the island and the Galápagos National Park successfully returned 118 hatchlings to their native island home. Partners returned to Pinzón Island in late 2014 and continued to observe hatchling tortoises (now older), indicating that natural recruitment is occurring on the island unimpeded. They also discovered a snail species new to science. These exciting results highlight the conservation value of this important management action. In early 2015, after extensive monitoring, partners confirmed that Pinzón and Plaza Sur Islands are now both rodent-free.
In 2017, the once IUCN Red-listed Extinct-in-the-Wild Pinzon Tortoise was down-listed to Vulnerable as a result of our conservation action.
SAVING THE WORLD’S RAREST SPECIES FROM EXTINCTION
1. PINZÓN GIANT TORTOISE
For nearly 150 years, invasive rats on Pinzón devoured every single tortoise egg or hatchling, leaving an aging population of tortoises to die off. In 1965, to address this issue and restore the population, the Galápagos National Park and Charles Darwin Research Station began harvesting clutches of eggs and raising them in captivity until they were at a “rat-proof” size to be released. While this was successful in increasing the tortoise population, the program depended on staffing and resources—which are not always available. By removing invasive rodents from the island, we provided a permanent solution, allowing these single-island endemic tortoises to reproduce in the wild, and hatchling tortoises to grow into giants.
2. NEW SNAIL SPECIES
In November 2014, Drs. Christine Parent and Andrew Kraemer conducted monitoring surveys of land snails on Pinzón and Rábida Islands following removal of invasive rats. During the survey on Pinzón, they found an unusual snail that did not seem to correspond to any Naesiotus species previously described. Parent and Kraemer soon discovered a healthy community of these small snails. Several dozen individuals were examined and it became clear that this is a new species to science, which the researchers are now working to formally describe.
Photo: Christine Parent
3. OPUNTIA GALAPAGEIA
This endangered plant species is found only in the Galápagos. It is a tree-like cactus that produces yellow flowers out of its spine clusters, which eventually develop into a spiny, oblong fruit—for which it gets its name, “prickly pear.” Invasive rats on Pinzón Island consumed the Opuntia’s seeds, preventing recruitment of one of the Pinzón tortoise’s key food plants. A sister species of Opuntia on Plaza Sur was also affected, impacting land iguanas. House mice on Plaza Sur burrowed into the root system and consumed their seed, causing the long-lived Opuntia’s to fall over and not regenerate.
4. GALÁPAGOS LAND IGUANA
There are three species of land iguanas in the archipelago, although recent genetic analyses indicate that land iguanas on Plaza Sur are distinct from other land iguana populations and may be a distinct species. Scientists are researching this possibility, helping inform how to best conserve this population of only 400 individuals. While these amazing creatures have no natural predators on this island, introduced house mice on Plaza Sur pose a threat to their continued existence. Removing invasive mice is a key part of a broader strategy to recover Plaza Sur land iguanas, their food plants, and other threatened species.
PROJECT MISSION
To protect and restore the rare and endangered plants and animals on Pinzón and Plaza Sur Islands by removing invasive species.
PROJECT VISION
Native species are once again thriving and free from the threat of extinction.
THE PROBLEM
Introduced rats on Pinzón Island prevented the Pinzón Giant Tortoises from successfully reproducing for nearly 150 years by preying on eggs and hatchlings. On Plaza Sur, invasive house mice ate the root systems of the long-lived Opuntia cactus, the favored food of Galápagos Land Iguanas.
THE SOLUTION
The Galápagos National Park, Island Conservation, Charles Darwin Foundation, The Raptor Center, and Bell Laboratories, Inc. implemented a project on Pinzón and Plaza Sur Islands in November and December 2012 to restore native species populations. In early 2015, through extensive monitoring, partners confirmed that Pinzón and Plaza Sur Islands are both now rodent-free and the islands’ plants and animals are showing positive signs of recovery.
Project Manager
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Karl CampbellSouth America Regional Director
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