Scientists stunned by 'remarkable' reappearance of species thought to be extinct: 'One of the most historic comebacks ever'

For the first time in centuries — and arguably millennia — it's a good time to be the leaf-toed gecko in the Galápagos.

Prior to 2019, the minuscule, centimeters-long species had only been found on the islands in their 5,000-year-old fossil records. But after conservation efforts successfully eradicated invasive, predatory rats, live specimens were found in both 2019 and 2021, New Scientist reported.

Specifically, the gecko was found on Rábida Island, which was part of a group of 11 Galápagos Islands that benefited from a restoration and rewilding project in 2011. The nonprofit group Island Conservation worked in tandem with Galápagos National Park, the Charles Darwin Foundation, and The Raptor Center to eliminate the invasive rat population by distributing poisoned bait from helicopters.

And it worked astonishingly well. The rats were confirmed as removed from Rábida just a year later, and several species were observed to be "immediately bouncing back," as New Scientist put it. One of these was the leaf-toed gecko.

"We conducted extensive monitoring prior to the removal of invasive rats and they weren't detected at all," Paula Castaño of Island Conservation said. "We believe a small population held on all those years and then, without invasive predators, it finally had the opportunity to recover and grow its population. You can call it one of the most historic comebacks ever or just a long-overdue reappearance."

The success underscores just how harmful even a single invasive species can be to a local ecosystem. From outcompeting native species for resources to demolishing prey species, invasive animals can wreak major havoc on an environment (and its local economy, too).

In many cases, these invasive animals arrive in new environments via human activity. Accidental transport — like in the case of the tiny New Zealand mud snail — and travel, trade, and illegal smuggling have all resulted in invasive species infiltrating new environments.

Fortunately, in Rábida's case, conservation efforts worked in time to reverse the damage done by the invasive rats.

"We found the 'extinct' gecko, rediscovered a snail last seen in 1906, as well as two other snail species being recorded on the island for the first time ever that are still being identified, and Galápagos hawks have returned and are thriving," Castaño said. "Nature is remarkable — allow it an opportunity to thrive and it comes roaring back."

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