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During her daily commute to the scientific station, biologist Miriam San José crouches near a small pond covered by dense vegetation and retrieves a small green sound device.

The device was left there overnight to record the distinctive calls of the Scinax quinquefasciatus, recognized by local scientists as an non-native species with consequences that scientists are just beginning to comprehend.

Despite abounding with unique wildlife – including ancient large turtles, swimming iguanas, and the famous finches that inspired Charles Darwin's evolutionary theory – the island chain off the shoreline of Ecuador had historically been free of amphibians.

During the 1990s, this changed. Several tiny tree frogs made their way from continental Ecuador to the archipelago, probably as hitchhikers on transport vessels.

Genetic studies indicate that, through time, there have been multiple accidental introductions to the archipelago, and the amphibians now have a firm foothold on several locations: Isabela and Santa Cruz.

The population is expanding so quickly that researchers have been struggling to keep track, calculating numbers in the hundreds of thousands on each island, across urban and farming areas, but also in the conservation Galápagos national park.

When San José marked frogs and attempted to find them in the subsequent week and a half, she could locate only a single marked frog occasionally, suggesting their numbers were enormous.

They calculated six thousand frogs in a solitary pond. "The calculations are still very low," states the researcher. "I am pretty sure there are additional numbers."

Acoustic Chaos and Growing Concerns

The amphibians' abundance is evident from the sound disruption they cause. "The number of frogs and the noise – it's really insane," comments the scientist.

For the researchers, their nightly mating calls are useful in determining their existence in remote areas, using recorders like the one outside the workplace.

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

"In the wet season, I constantly hear their calls and they're really loud," says a local coffee farmer from Santa Cruz.

"At first it was a surprise, seeing the initial frogs in the region," says Larrea Saltos, who started noticing their abundance about several years ago when one leaped on her hand as she was walking out of her house.

Ecological Impact Stays Unknown

The noise isn't the fundamental problem, however. While the amphibians has been in the Galápagos for nearly three decades, scientists still know limited information about its impact on the archipelago's delicately balanced terrestrial and aquatic environments.

On archipelagos, it is very typical for invasive species to prosper, as they have few of their enemies. The Galápagos counts over sixteen hundred introduced species, many of which are significantly disrupting the survival of its endemic ones.

A recent research suggests the invasive amphibians are hungry bug consumers, and might be disproportionately consuming rare bugs found exclusively on the islands, or reducing the nutrition of the islands' uncommon birds, disrupting the ecosystem balance.

Unique Characteristics and Management Difficulties

The Galápagos amphibians have shown some atypical characteristics, including living in slightly salty water, which is uncommon for amphibians.

Their metamorphosis stage is also highly variable, with some tadpoles turning into frogs very rapidly and others taking a extended period: the researcher witnessed one which stayed as a larva in her laboratory for six months.

"We truly don't know this part," she says, concerned the larvae could be impacting the islands' clean water, a very scarce commodity in the islands.

Methods to curb the amphibians in the early 2000s were mostly ineffective. Park rangers tried collecting significant quantities by manual methods and gradually raising the salt content of lagoons in without success.

Research suggests applying coffee – which is extremely toxic to amphibians – or using electrical methods could help, but these approaches aren't necessarily safe for other rare Galápagos species.

Lacking solutions to more of the fundamental issues about their biology 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 techniques and genetic examination will help her team understand of the invader, funding for the research has been hard to come by.

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