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On her regular commute to the research facility, biologist the researcher crouches near a small water body surrounded by thick vegetation and collects a small plastic audio device.

She had placed there overnight to record the distinctive croaks of the Fowler's snouted treefrog, known by local researchers as an invasive species with consequences that scientists are just beginning to comprehend.

Although teeming with unique animals – including ancient large turtles, swimming iguanas, and the well-known birds that sparked Darwin's theory of evolution – the island chain off the coast of Ecuador had historically been free of frogs and toads.

During the 1990s, this shifted. Several small amphibians traveled from mainland Ecuador to the islands, probably as stowaways on cargo ships.

DNA research suggest that, through time, there have been multiple accidental arrivals to the archipelago, and the frogs now have a strong foothold on several locations: multiple locations.

The population is expanding so rapidly that researchers have been finding it difficult to monitor, calculating populations in the hundreds of thousands on each island, across urban and agricultural areas, but also in the protected natural reserve.

When the biologist marked frogs and attempted to recapture them in the subsequent week and a half, she could find only a single tagged frog from time to time, suggesting their populations were enormous.

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

Deafening Noise and Growing Concerns

The frogs' proliferation is clear from the sound chaos they create. "The number of frogs and the noise – it's really insane," comments San José.

For the scientists, their nightly vocalizations are helpful in estimating their existence in far-flung areas, using audio devices like the one near the workplace.

But local agricultural workers say the calls are so raucous they keep them up at night.

"During the wet season, I regularly hear their calls and they're really loud," says a local coffee farmer from the island.

"Initially it was a shock, observing the initial frogs in the region," says the farmer, who started noticing their abundance about three years ago when one jumped on her palm as she was walking out of her front door.

Ecological Impact Stays Unknown

The sound isn't the fundamental problem, however. While the species has been in the Galápagos for nearly 30 years, scientists still know very little about its impact on the islands' delicately balanced terrestrial and aquatic ecosystems.

On islands, it is very typical for invasive species to thrive, as they have few of their enemies. The islands has over sixteen hundred introduced species, many of which are significantly disrupting the survival of its native ones.

A recent research suggests the non-native amphibians are voracious bug eaters, and might be disproportionately eating rare insects found only on the archipelago, or depleting the food sources of the region's uncommon avian species, affecting the food chain.

Unique Characteristics and Control Challenges

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

Their development stage is also extremely variable, with some tadpoles becoming frogs very rapidly and others taking a extended period: the researcher witnessed one which stayed as a tadpole in her lab for half a year.

"We really don't know this part," she says, worried the tadpoles could be affecting the region's clean water, a very limited resource in Galápagos.

Techniques to curb the amphibians in the beginning of the century were mostly unsuccessful. Park rangers tried collecting significant quantities by hand and gradually raising the salinity of lagoons in without success.

Research suggests applying coffee – which is extremely toxic to frogs – or using electrocution could help, but these approaches aren't necessarily safe for other rare island organisms.

Without answers to more of the fundamental questions about their biology and effect, removing the frogs might not even be the correct way to proceed, says the biologist.

Funding Challenges for Research

While she expects the increasing use of environmental DNA methods and DNA analysis will help her team make sense of the invader, funding for the research has been difficult to obtain.

"Everyone wants to give support for preserving frogs," says San José. "But it's harder to find financial backing for an invasive frog that you might want to manage."