Some presumed extinct harlequin frogs have been rediscovered.

One group of jewel-encrusted frogs is making a comeback in Central and South America.

It was believed that the iconic Jambato harlequin frog of Ecuador (seen here) became extinct in the late 1980s. In 2016, it became one of the many rediscovered members of its genus since 2000. K. JAYNES

Harlequin frogs, a genus with over 100 brightly colored species, were among the amphibian groups hardest hit by a skin-eating chytrid fungus in the 1980s (SN: 32819). With the added pressures of climate change and habitat loss, approximately 70 percent of known harlequin frog species are now listed as extinct or critically endangered due to their susceptibility to the disease.

In recent years, however, roughly one-third of harlequin frogs believed extinct since the 1950s have been rediscovered, according to a study published in the December issue of Biological Conservation.

According to Kyle Jaynes, a conservation biologist at Michigan State University in Hickory Corners, this is a rare "glimmer of hope" in an otherwise bleak time for amphibians around the world.

The resurgent frog

Hearing about the Jambato harlequin frog set Jaynes on the path to determining how many harlequin frogs have returned from the verge of extinction (Atelopus ignescens). This black and orange frog was once so common in the Andes of Ecuador that its common name is derived from the Kichwa word for "frog," "jampatu."

Then the fungus appeared. From 1988 to 1989, the frogs "completely vanished," according to Jaynes. Years were spent searching for traces of the frogs. Scientists conducted extensive surveys, and pastors offered rewards to congregants who discovered one.

In 2016, a young boy discovered a small population of Jambato frogs in an Ecuadorian mountain valley. According to Luis Coloma, a researcher and conservationist at the Centro Jambatu de Investigación y Conservación de Anfibios in Quito, Ecuador, "it seemed like a miracle" that a species that had been missing for decades had been rediscovered.

Coloma operates a breeding program for Jambato and other endangered Ecuadorian frogs. In 2019, Jaynes was part of a group of scientists who visited Coloma's laboratory to determine how these frogs had evaded death. After the return of the Jambato frogs, the team began hearing reports of other long-lost harlequin species being spotted for the first time in years.

These accounts prompted Jaynes, Coloma, and their colleagues to comb through reports to determine the number of harlequin frogs that had reappeared. Of the more than 80 species that have vanished since 1950, as many as 32 have been spotted in the last two decades — a far greater number than anticipated by the team.

"I believe we were all surprised," Jaynes states.

Ensuring conservation

The report contains qualifications. The majority of species appear to have avoided extinction by a hair's breadth, and their numbers remain perilously low. Thus, extinction remains a very real possibility. Here, we have a second chance, says Jaynes. However, there is still much work to be done to conserve these species.

Understanding how the rediscovered species has managed to survive thus far is crucial to ensuring their survival. Some scientists hypothesize that amphibians living at higher altitudes may be more susceptible to the fungus because it prefers cooler temperatures.

Kyle Jaynes, a conservation biologist, examines a Rio Faisanes stubfoot toad (Atelopus coynei), one of the critically endangered harlequin frog species found in Ecuador. ALEX ACHIG-VEGA

Kyle Jaynes, a conservation biologist, examines a Rio Faisanes stubfoot toad (Atelopus coynei), one of the critically endangered harlequin frog species found in Ecuador.

However, a cursory analysis conducted by Jaynes and colleagues revealed that harlequin frogs are being rediscovered at all elevations throughout their range, suggesting that something else may be at play. Jaynes suspects that there is a biological basis for the survival of harlequin frogs, such as the development of fungus resistance (SN: 32918).

Valerie McKenzie, a disease ecologist at the University of Colorado Boulder who was not involved in the study, says that studies like this can serve as a "launching pad" for understanding how amphibians might survive the dual threats of disease and climate change.

In the meantime, the fact that people are beginning to notice the reappearance of species that were once thought to be extinct "gives me a lot of hope that other species that are more difficult to observe — because they are nocturnal or live high in the canopy — are also recovering," she says. It encourages me to believe that we should go look for them.


Harlequin frog rediscoveries by K.E. Jaynes et al. provide insight into species persistence in the face of drastic amphibian declines. December 2022, Volume 276 of Biological Conservation, DOI: 10.1016/j.biocon.2022.109784.


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