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On her regular commute to the research facility, scientist the researcher stoops near a small water body surrounded by thick plants and collects a small plastic audio recorder.

The device was left there through the night to record the characteristic croaks of the Scinax quinquefasciatus, known by local researchers as an non-native species with effects that scientists are starting to understand.

Although teeming with remarkable animals – including ancient giant tortoises, marine lizards, and the well-known finches that sparked Charles Darwin's theory of evolution – the island chain off the coast of South America had historically been devoid of amphibians.

During the 1990s, this changed. Several tiny amphibians made their way from mainland the mainland to the islands, likely as hitchhikers on transport vessels.

Genetic research indicate that, over the years, there have been repeated accidental introductions to the islands, and the amphibians now have a strong presence on several islands: Isabela and Santa Cruz.

The population is growing so quickly that scientists have been struggling to keep track, calculating populations in the hundreds of thousands on each island, across developed and farming areas, but also in the conservation natural reserve.

When the biologist marked frogs and attempted to find them in the following 10 days, she could find just one tagged frog from time to time, indicating their numbers were massive.

They estimated 6,000 frogs in a single pond. "The calculations are still very low," says the researcher. "I am pretty sure there are additional numbers."

Deafening Noise and Growing Concerns

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

For the researchers, their nightly vocalizations are helpful in determining their existence in remote areas, using recorders like the one near the office.

But local agricultural workers say the calls are so raucous they prevent sleep at night.

"During the rainy period, I constantly hear their calls and they're really loud," says Jadira Larrea Saltos from the island.

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

Ecological Impact Remains Unknown

The sound isn't the primary problem, however. While the species has been in the islands for almost 30 years, scientists still know very little about its effect on the archipelago's precariously balanced land and water ecosystems.

On islands, it is very common for non-native species to prosper, as they have few of their enemies. The Galápagos has over sixteen hundred invasive species, many of which are significantly affecting the survival of its native ones.

A recent research indicates the invasive amphibians are voracious bug eaters, and might be disproportionately eating rare bugs found only on the archipelago, or depleting the food sources of the region's uncommon avian species, disrupting the food chain.

Unique Characteristics and Control Challenges

The Galápagos amphibians have exhibited some atypical traits, including living in brackish water, which is rare for frogs.

Their development process is also highly variable, with some tadpoles becoming frogs very quickly and others taking a extended period: the researcher observed one which stayed as a larva in her lab for half a year.

"We truly don't know this aspect," she says, worried the larvae could be impacting the region's clean water, a very scarce commodity in Galápagos.

Techniques to control the frogs in the beginning of the century were mostly unsuccessful. Conservation officers tried collecting large numbers by hand and slowly increasing the salt content of lagoons in vain.

Research suggests applying caffeine – which is extremely poisonous to amphibians – or using electrocution could help, but these methods aren't necessarily safe for other uncommon island species.

Without solutions to more of the fundamental issues about their lifestyle and effect, removing the frogs might not even be the right way to proceed, says the biologist.

Financial Obstacles for Research

While she expects the growing use of eDNA techniques and genetic analysis will assist her team make sense of the invasive species, financial support for the research has been hard to come by.

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