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During her regular commute to the research facility, scientist the researcher crouches near a small water body covered by thick vegetation and collects a compact plastic sound device.

The device was left there overnight to record the characteristic calls of the Scinax quinquefasciatus, known by local researchers as an invasive threat with effects that experts are starting to comprehend.

Despite abounding with unique animals – such as centuries-old large turtles, swimming lizards, and the well-known birds that inspired Charles Darwin's theory of evolution – the island chain near the shoreline of Ecuador had historically been devoid of amphibians.

During the 1990s, this shifted. Some tiny amphibians traveled from continental the mainland to the islands, likely as hitchhikers on cargo ships.

DNA research indicate that, through time, there have been repeated accidental arrivals to the islands, and the frogs now have a firm foothold on several islands: multiple locations.

The population is growing so rapidly that researchers have been finding it difficult to keep track, estimating populations in the millions on every island, across urban and agricultural areas, but also in the conservation Galápagos national park.

When San José marked frogs and attempted to find them in the following 10 days, she could locate just one marked frog from time to time, suggesting their numbers were massive.

They calculated 6,000 frogs in a single pond. "Our estimates are still very low," states the researcher. "I am pretty sure there are even more."

Acoustic Chaos and Rising Worries

The amphibians' abundance is evident from the acoustic disruption they create. "The amount of frogs and the noise – it's really insane," says the scientist.

For the scientists, their nightly mating calls are useful in determining their presence in remote areas, using audio devices like the one outside the office.

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

"During the rainy period, I regularly hear their croaks and they're extremely loud," says Jadira Larrea Saltos from Santa Cruz.

"Initially it was a shock, seeing the first frogs in the area," says the farmer, who started observing their large numbers about several years ago when one leaped on her hand as she was walking out of her front door.

Environmental Consequences Stays Unknown

The noise isn't the fundamental problem, though. While the species has been in the islands for almost three decades, experts still know limited information about its impact on the archipelago's delicately balanced terrestrial and aquatic ecosystems.

On islands, it is very common for non-native organisms to prosper, as they have none of their natural predators. The Galápagos counts 1,645 invasive types, many of which are seriously affecting the survival of its endemic ones.

A recent research suggests the non-native amphibians are voracious insect consumers, and might be disproportionately consuming uncommon bugs found only on the islands, or reducing the nutrition of the islands' uncommon avian species, disrupting the food chain.

Unusual Traits and Control Challenges

The Galápagos amphibians have shown some atypical characteristics, including surviving in brackish water, which is uncommon for frogs.

Their metamorphosis process is also extremely inconsistent, with some larvae becoming frogs very quickly and others taking a extended period: San José witnessed one which remained as a tadpole in her lab for half a year.

"We really don't know this part," she says, worried the larvae could be impacting the islands' clean water, a very scarce resource in Galápagos.

Techniques to curb the amphibians in the beginning of the century were largely ineffective. Conservation officers tried collecting significant quantities by manual methods and slowly increasing the salinity of ponds in vain.

Studies suggests spraying coffee – which is extremely toxic to amphibians – or using electrocution could assist, but these methods aren't necessarily safe for other rare Galápagos species.

Lacking solutions to more of the basic questions about their biology and effect, culling the amphibians might not even be the right way to proceed, says San José.

Financial Obstacles for Research

While she expects the growing use of environmental DNA methods and DNA examination will help her team understand of the invasive species, financial support for the research has been difficult to come by.

"Everyone wants to give funding for preserving frogs," says the researcher. "But it's more difficult to find funding for an invasive frog that you might want to manage."