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.