This article is a reprint from Newsweek published on December 12, 2022 by Aristos Georgiou. You can find the press release about the species recovery here.

A “healthy” population of geckos has been documented on one of the Galápagos Islands where the reptiles had been considered locally extinct.

Scientists observed the geckos on Rábida Island during an eight-day research trip last month, the non-profit Island Conservation said in a statement. The small, carnivorous lizards, which belong to the gecko genus (group of species) Phyllodactylus, were previously only known on Rábida from subfossil records dating back approximately 5,700 years ago.

The term “subfossil” is used to refer to the remains of animals that are not old enough to be considered true fossils but are still partially fossilized.

Researchers are in the process of conducting genetic analysis to determine if these geckos represent a new species, Sally Esposito, a spokesperson for Island Conservation, told Newsweek. The islands are already home to at least nine species of endemic geckos.

The Galápagos Islands are a remote archipelago of volcanic islands in the Pacific Ocean, located more than 560 miles west of the South American continent, that form part of the Republic of Ecuador.

The archipelago is a protected area that is renowned for its array of unique flora and fauna species that are not found anywhere else in the world. The species of the islands were famously studied by Charles Darwin in the early 1800s with his observations inspiring the development of his theory of evolution.

The islands have been described as a showcase for evolutionary processes. Their extreme isolation, equatorial location at the confluence of three ocean currents, and wide variety of habitats have created ideal conditions for the development of unique plants and animals, including the giant tortoise, marine iguana and Galápagos penguin.

The various islands in the archipelago are sometimes home to different types of the same animal. For example, different finch and tortoise species can be found on each of the main islands.

The healthy gecko population on Rábida Island was documented during a research assignment conducted by a team of researchers led by officials from Galápagos National Park and Island Conservation. The team also visited Pinzón Island as part of their research.

The aim of the trip was to investigate how wildlife has recovered on these two islands—located in the center of the archipelago—a decade after the removal of invasive rodents, namely, rats.

Preliminary findings indicate that the removal of these invasive rodents, which wreaked havoc on the local ecosystems by consuming native species and affecting the reproduction of many reptiles and birds, has led to significant ecological improvements due to the disappearance of these predators.

Rábida and Pinzón have once again become suitable habitats for endemic Galápagos species that had never been recorded on the islands before, were considered locally extinct, or were present only in very low numbers.

The first time a gecko was recorded on Rábida after the removal of invasive species was back in 2013, but at that time only a few individuals were observed, Esposito said. During the most recent trip though, researchers were able to document a healthy, well-established population.

Aside from the geckos, the team recorded a healthy and growing population of Galápagos rails—a small, ground-living bird endemic to the islands—on Pinzón where they had never been reported before. Scientists think the birds may have migrated from a neighboring island before establishing themselves.

The team also made several observations of cactus finches on Pinzón, a bird species that was considered locally extinct there for more than 40 years.

In 2019, scientists reported giant tortoises successfully hatching on Pinzón for the first time in more than 150 years. The reptiles are now reproducing naturally without human assistance—a remarkable comeback. Over the course of this period, invasive rats had been feeding on the eggs and hatchlings of the tortoises on the island, resulting in an aging population that was not capable of sustaining itself.

“The actions implemented in the eradication of introduced species and in the protection and recovery of species have been effective,” Christian Sevilla, an official from the Galápagos National Park, said in a statement.

Esposito said restoring an island is like “hitting a reset button“—the island’s natural ecosystem recovers, and with that comes the wildlife that sustains it.

“Rewilding islands immediately benefit native wildlife and provides them the opportunity to thrive, which in turn nourishes the marine environment,” she said.