Tag Archives: frog calls

Hope Returns to Panama’s Forests With the Rediscovery of Four Missing Frog Species 

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Smithsonian scientist Brian Gratwicke and colleagues describe how emerging technology aided the remarkable rediscovery of four amphibian populations thought to have vanished from Panama’s mountain forests. 

By Brian Gratwicke 

We’re thrilled to share some encouraging news from the mountains of Panama. After nearly two decades of silence, we’re hearing the calls of frogs that were thought to be lost forever. The rediscovery of four amphibian populations missing since the mid-2000s offers rare and encouraging news for some of the world’s most threatened animals. 

A coronated treefrog (Triprion spinosus) inside a laboratory habitat at Smithsonian Tropical Research Institute in Gamboa in Gamboa, Panama. (Roshan Patel/Smithsonian)

Our team at the Panama Amphibian Rescue and Conservation project includes several researchers with decades of field experience. But even for the most seasoned researchers, documenting missing species remains one of conservation biology’s greatest challenges. How do you prove a species is truly gone and not just extremely difficult to find? 

In recent decades, the fungal disease chytridiomycosis wiped out amphibian populations worldwide, causing declines and extinctions in nearly a hundred species. We focused our search on species that vanished from central Panama during the devastating chytrid outbreaks of 2004-2009 including the potentially extinct Rabb’s fringe-limbed treefrog  (Ecnomiohyla rabborum). The 2024 IUCN Global Amphibian Assessment flagged several species from central Panama as missing, but officially declaring a species extinct requires years of concerted, documented effort.  

With recent advances in acoustic recording and analysis technology, and armed with a recording of the Rabb’s treefrog call from the Atlanta Botanical Garden, we saw an opportunity to revisit the forests with new tools. By focusing on Rabb’s treefrog, we also sought to honor the legacy of George Rabb, an influential amphibian conservationist whose work continues to inspire this research.   

A view of the Altos de Campana National Park in Panama. The Panama Amphibian Rescue and Conservation Project is a partnership between the Smithsonian Institution, the Cheyenne Mountain Zoo and Zoo New England that seeks to rescue and establish assurance colonies of amphibian species that are in extreme danger of extinction throughout Panama. (Roshan Patel/Smithsonian)

In 2022 and again in 2024, our team deployed autonomous recording units – essentially small microphones that automatically capture forest sounds – across three localities in Panama’s central cordillera. During the early rainy season, we recorded the soundscape for one minute of sound every ten minutes, day and night.  We also conducted traditional visual and auditory frog surveys along a 100-meter transect.  

Smithsonian researcher Roberto Ibáñez places an audiomoth used to record 1 minute of sound every 10 minutes for acoustic analysis in Altos de Campana National Park. (Brian Gratwicke / Smithsonian)

The results were astonishing. Using sophisticated pattern-matching software to analyze the recordings, we documented four species on the IUCN Red List of Threatened Species that had seemingly vanished from these forests.  Most remarkably, we detected more than 400 calls from the endangered Vicente’s dart frog (Oophaga vicentei), a metallic green-and-black species that was presumed extinct in this region according to the IUCN. We also found the Boquete rocket frog (Silverstoneia nubicola), which disappeared from Altos de Campana National Park nearly 20 years ago, and the crowned treefrog (Triprion spinosus), a hole-breeding specialist that survives in Mexico and Costa Rica but has not been seen in Panama’s forests for a decade. 

A gallery of frogs rediscovered through acoustic monitoring and physical surveys in central Panama. Images show a Vicente’s poison frog (top left), a Boquete rocket frog (top middle), a  Lemur leaf frog (top right), a Veragua fringe-limbed treefrog (bottom left), and a crowned treefrog (bottom right).

The technology proved to be remarkably effective. Our autonomous recording units detected common frog species at twice as many locations as traditional day-and-night surveys alone.  

In total, the devices captured more than 128,000 one-minute recordings, creating an acoustic archive that reveals patterns about frog behavior that we’ve never documented before. For instance, we discovered that the Boquete rocket frog calls primarily at dawn and dusk, a narrow window that helps explain why earlier surveys may have missed it. 

While we didn’t find evidence of the critically endangered Rabb’s fringe-limbed treefrog, we did make a surprising discovery. Along our transect, we encountered a juvenile frog of the same Ecnomiohyla genus on our transect with a malformed hand. We brought him back to the Amphibian Rescue Center for genetic testing. Results revealed it was not Rabb’s frog, but the Veragua fringe-limbed treefrog (Ecnomiohyla veraguensis). Our staff named him Han Solo.  

Because of his deformity, we did not release the frog back into the wild – but he offered an unexpected gift. We recorded his adorable Chihuahua-like bark on video and used it as a template for pattern-matching. That recording led us to detect other Veragua fringe-limbed treefrogs at that same site, validating our approach for locating elusive, canopy-dwelling species. 

Across our survey sites, the entire amphibian community is showing signs of partial recovery. Frog abundance now averages about six individuals per 100-meter transect—still below pre-decline levels, but a significant improvement from the devastation of 2006.  

The fungal pathogen Batrachochytrium dendrobatidis persists in the environment, infecting about 21% of amphibians we tested. Even so, several species appear to be rebounding, suggesting some may be developing disease resistance. For amphibian populations once considered doomed, this discovery offers genuine hope for the future. 

Not all species have returned. Pratt’s rocket frog (Colostethus pratti), once the most abundant rocket frog at Cerro Campana, was absent from that locality despite recovering elsewhere. This absence presents an opportunity for conservation action – we are now conducting experimental translocations of potentially disease-resistant individuals to test whether we can take human-assisted actions to help restore lost species and revitalize the forest’s natural soundscape. 

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The Panama Amphibian Rescue and Conservation Project is a partnership between the Smithsonian’s National Zoo and Conservation Biology Institute, the Smithsonian Tropical Research Institute, Cheyenne Mountain Zoo and Zoo New England.  This project was sponsored by the Shared Earth Foundation in honor of prominent amphibian advocate and conservationist George Rabb. Our staff are supported by the Bezos Earth Fund, an anonymous foundation and other sustaining donors 

 Our findings were recently published in Frontiers in Amphibian and Reptile Science: 

 Gratwicke, B.,  Guerrel, J., Garces, O.,  Illueca, E.,  Weisenbeck, N.J.,  Deichmann, J.L., Ibáñez, R.  Rediscovery of frogs of conservation concern in Panama using passive acoustic monitoring and pattern-matching analysis   Front. Amphib. Reptile Sci. 3:1736880. doi: 10.3389/famrs.2025.1736880   

Restoring Nature’s Soundscape

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In the lush forests of Panama, a small rocket frog called Pratt’s rocket frog (Colostethus pratti) once filled the air with its distinctive calls. Then, a deadly fungal disease called chytridiomycosis swept through, decimating amphibian populations across Central America. In places like Altos de Campana National Park, where these frogs were once common, they vanished completely.

Pratt's rocket frog Colostethus pratti

During our acoustic monitoring research, we discovered that some C. pratti populations were bouncing back, even with the fungal pathogen still present. This suggested the frogs may have evolved resistance to the disease that nearly wiped them out. In Panama, we often find frogs that declined from the pathogen either recovering or persisting at low levels. But the fact that they declined to extinction in one national park while recovering elsewhere offered a unique opportunity: a human-assisted recovery of wild rocket frogs through translocation. In the United States, mountain yellow-legged frogs have recovered using this approach, and we hoped to replicate this success in Panama.

Twelve breeding pairs were collected from the recovering population at Bajo Bonito and brought to a quarantine facility, where they were tested for the fungus and treated preventatively. Male-female pairs then spent two weeks acclimating in mesh enclosures filled with leaf litter at the release site. Previous trials had shown that frogs released directly into new habitats dispersed rapidly and suffered higher mortality rates. This gentler approach gave them time to adjust before venturing into their new home.

The team is using acoustic monitoring technology—an array of automated recorders listening for the frogs’ loud, distinctive calls—to track the population over time. This cost-effective method will reveal whether the frogs survived and dispersed. For now, the forests of Altos de Campana have restored a missing voice to the soundscape—a small but significant victory in the fight to preserve the planet’s embattled amphibians. It’s still too early to evaluate whether the population will persist, but watch this space for updates!