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During her daily commute to the scientific station, scientist the researcher crouches near a shallow water body covered by dense plants and retrieves a small plastic audio device.

She had placed there through the night to capture the distinctive croaks of the Fowler's snouted treefrog, known by local scientists as an non-native species with consequences that experts are starting to understand.

Although teeming with remarkable animals – including ancient giant tortoises, marine iguanas, and the well-known birds that inspired Darwin's theory of evolution – the island chain off the coast of Ecuador had long remained devoid of amphibians.

During the 1990s, this changed. Several small tree frogs made their way from mainland the mainland to the archipelago, likely as stowaways on cargo ships.

DNA research suggest that, through time, there have been repeated accidental introductions to the archipelago, and the amphibians now have a firm presence on several islands: Isabela and Santa Cruz.

The numbers is growing so quickly that researchers have been finding it difficult to keep track, calculating populations in the hundreds of thousands on every island, across developed and agricultural areas, but also in the protected natural reserve.

When San José marked frogs and attempted to find them in the following week and a half, she could find just one tagged frog from time to time, indicating their numbers were massive.

They calculated 6,000 frogs in a solitary pond. "Our estimates are still very low," says the researcher. "I am quite certain there are additional numbers."

Deafening Noise and Rising Worries

The frogs' proliferation is clear from the sound chaos they cause. "The number of frogs and the sound – it's truly insane," comments the scientist.

For the scientists, their nocturnal mating calls are helpful in determining their existence in far-flung areas, using audio devices like the one near San José's workplace.

But nearby farmers say the sounds are so loud they keep them up at night.

"In the wet season, I regularly hear their croaks and they're extremely loud," says a local coffee farmer from the island.

"At first it was a surprise, seeing the first frogs in the area," says the farmer, who started observing their abundance about three years ago when one jumped on her palm as she was walking out of her house.

Environmental Consequences Stays Unknown

The noise isn't the fundamental problem, though. While the species has been in the Galápagos for nearly 30 years, experts still know very little about its effect on the islands' delicately balanced land and water environments.

On islands, it is very typical for non-native species to prosper, as they have none of their enemies. The Galápagos counts over sixteen hundred introduced types, many of which are significantly disrupting the survival of its native ones.

A recent research indicates the invasive amphibians are voracious bug eaters, and might be disproportionately consuming uncommon bugs found exclusively on the archipelago, or reducing the nutrition of the region's rare avian species, affecting the ecosystem balance.

Unique Characteristics and Management Difficulties

The island amphibians have shown some unusual traits, including living in slightly salty water, which is uncommon for amphibians.

Their development process is also highly variable, with some tadpoles turning into frogs very quickly and others taking a long time: San José observed one which stayed as a tadpole in her laboratory for six months.

"We truly don't know this part," she says, worried the larvae could be impacting the region's clean water, a very limited resource in the islands.

Techniques to control the frogs in the beginning of the century were largely ineffective. Conservation officers tried collecting large numbers by manual methods and slowly raising the salinity of ponds in without success.

Research suggests spraying caffeine – which is highly toxic to amphibians – or using electrical methods could help, but these methods aren't necessarily safe for other uncommon Galápagos species.

Without solutions to more of the fundamental questions about their lifestyle and impact, culling the amphibians might not even be the right way to advance, says the biologist.

Funding Challenges for Research

While she expects the growing use of eDNA methods and genetic analysis will assist her team understand of the invader, funding for the research has been hard to come by.

"Everyone wants to give support for protecting frogs," says San José. "But it's more difficult to find financial backing for an introduced frog that you might want to manage."