🔗 Share this article The Galápagos Islands Lacked Any Native Amphibians. Then Hundreds of Thousands of Frogs Arrived During her regular commute to the scientific station, scientist the researcher stoops near a small pond surrounded by thick vegetation and collects a compact plastic sound device. She had placed there overnight to capture the distinctive croaks of the Fowler's snouted treefrog, known by local scientists as an non-native species with effects that experts are starting to understand. Although teeming with unique wildlife – including ancient large turtles, swimming lizards, and the famous finches that inspired Charles Darwin's theory of evolution – the Galápagos archipelago near the shoreline of South America had long remained devoid of frogs and toads. During the 1990s, this shifted. Several tiny tree frogs traveled from mainland Ecuador to the archipelago, probably as stowaways on transport vessels. Fowler’s snouted tree frogs arrived in the 1990s and have taken hold on Isabela and Santa Cruz islands. Genetic research indicate that, through time, there have been repeated accidental introductions to the archipelago, and the frogs now have a strong foothold on several locations: multiple locations. The numbers is expanding so quickly that scientists have been finding it difficult to keep track, calculating numbers in the hundreds of thousands on every island, across urban and agricultural areas, but also in the conservation natural reserve. When the biologist marked frogs and attempted to recapture them in the subsequent week and a half, she could locate only a single tagged frog occasionally, indicating their numbers were massive. They estimated six thousand frogs in a solitary pond. "Our estimates are still very conservative," says the researcher. "I'm quite certain there are additional numbers." Deafening Noise and Growing Concerns The frogs' abundance is evident from the acoustic disruption they cause. "The amount of frogs and the sound – it's truly incredible," says the scientist. For the researchers, their nocturnal mating calls are useful in determining their presence in remote areas, using audio devices like the one near the workplace. But nearby agricultural workers say the calls are so raucous they keep them up at night. "During the wet season, I regularly hear their croaks and they're really loud," says Jadira Larrea Saltos from the island. "At first it was a surprise, observing the initial frogs in the region," says the farmer, who started observing their large numbers about several years ago when one jumped on her palm as she was walking out of her front door. Environmental Consequences Remains Unknown The noise isn't the fundamental problem, however. While the amphibians has been in the Galápagos for almost three decades, scientists still know very little about its impact on the islands' precariously balanced land and water environments. Researchers are discovering more about the amphibians, including that they can remain as larvae for as long as six months. On islands, it is very typical for non-native species to thrive, as they have few of their natural predators. The islands counts over sixteen hundred invasive species, many of which are seriously disrupting the survival of its native ones. A 2020 study suggests the invasive amphibians are voracious bug consumers, and might be disproportionately eating rare insects found only on the islands, or reducing the food sources of the region's uncommon birds, affecting the ecosystem balance. Unusual Traits and Management Difficulties The island frogs have shown some unusual characteristics, including surviving in brackish water, which is rare for amphibians. Their development process is also extremely inconsistent, with some larvae becoming frogs very quickly and others taking a extended period: San José observed one which remained as a tadpole in her lab for half a year. "We truly don't know this aspect," she says, concerned the tadpoles could be affecting the region's clean water, a very limited commodity in Galápagos. More research is needed to establish the best way to manage the amphibians without affecting other organisms. Methods to curb the amphibians in the early 2000s were largely unsuccessful. Conservation officers tried capturing significant quantities by manual methods and gradually raising the salt content of lagoons in without success. Research suggests spraying coffee – which is extremely toxic to amphibians – or using electrical methods could assist, but these methods aren't always safe for other rare Galápagos species. Without solutions to more of the basic questions about their lifestyle and impact, removing the frogs might not even be the correct way to advance, says San José. Financial Obstacles for Research While she hopes the growing use of eDNA methods and DNA examination will help her group make sense of the invader, funding for the project has been hard to obtain. "Everybody wants to give support for protecting frogs," says San José. "But it's more difficult to find funding for an introduced frog that you might want to control."