The Critically Endangered harlequin frog (Atelopus varius), which until recently was thought to be extinct following numerous surveys across its former range, has been rediscovered in southern Costa Rica in the Talamanca Mountains, according to a recent article published by an international team of researchers.

The harlequin frog was relatively common in areas of Costa Rica and Panama until 1988 when populations quickly declined like many other species in frogs in the region. Only 6 years later, the harlequin frog was thought to be extinct – a casualty of the invasive and infectious chytrid fungus implicated in the extinction of hundreds of amphibian species globally.

Scientists continued to look for the harlequin frog for 10 years when 2 individuals were located in an inaccessible are near Manuel Antonio National Park, but they have not been seen since YEAR. A handful of other individuals of this once common frog have been found on expeditions to remote areas in Panama.

“We have been studying this population of harlequin frogs since 2009. Fortunately, it is located in a private reserve in the very south of Costa Rica, where access can be controlled to protect their habitat. After several years of monitoring we found that this population is healthy and shows no signs of infection by the aggressive chytrid fungus,” explained José González-Maya, lead author of the report and Scientific Director of the Sierra to Sea Institute and ProCAT Conservation.

“The next steps for us are to pull together resources to implement a long term monitoring and recovery program for the species” says González-Maya, “finding it is only the first step, now we have the difficult task of ensuring its survival against many odds. As we develop a recovery plan we will need to bring together local and international partners to build a strong team with sufficient resources to ensure recovery.”

The research team worked with members of the local community to monitor the population of more than 100 individuals and confirm that this population is breeding. Using this knowledge, they also built fences and worked with the local community protect the habitat of the population.

“We wanted to make sure the population is healthy and stable rather than reporting on a single individual. When the fungus first came through this area, scientists found many individuals of this species dead along this same river,” said Sarah Wyatt (JOSE??), currently a biodiversity associate with the Global Environment Facility.

The team continues its efforts to monitor and protect this population and its habitat. This species is found in multiple conservation breeding programs, so the research team’s first priority is ensuring the survival and growth of this population in this area.

“I’m particularly excited about finding this population, because based on what we know about this disease and species going extinct in its wake, this population shouldn’t be here. It provides hope that there are other populations surviving in other areas,” said Jan Schipper, Adjunct Professor at Arizona State University and Director of the Sierra to Sea Institute. Schipper then shared the team’s plan to search surrounding areas to look for other populations and other species that are still thought to be extinct.

“Finding this population is great news for conservation of harlequin frogs, and it raises a number of important questions about whether it is a resilient population that developed resistance to the fungus or whether some individuals simply survived and are now repopulating. Regardless, there is still much work to be done. Globally more than 1 in 3 amphibians are threatened with extinction, and better understanding this population will shed light on conservation strategies for other species,” explained Robin Moore, Conservation Officer for the Amphibian Survival Alliance, who was not part of the study.

Amphibians are often called the bellwethers of environmental change. Living in water with sensitive skin, the loss of frogs may be a warning of the damage being done to the environment that will affect us all.

“Rediscovering this population highlights the importance of the conservation efforts made by local residents to protect their natural resources, especially the owner of the property where the harlequin was rediscovered. If their habitat hadn’t been protected, these frogs would never have had a fighting chance against this disease,” explained Tom Brooks, Chief Scientist of the International Union for the Conservation of Nature, who was not part of the study.

The research team is also working with the community of researchers around the world who are working to understand and fight the chytrid fungus. They hope that this population can help scientists better understand the disease and help conserve other species.
This study was an international effort with researchers from the National Autonomous University of Mexico (UNAM), University of Mississippi, and the University of Arizona-West working with the Sierra to Sea Institute and ProCAT Conservation. The study was published in the Dutch journal Amphibia-Reptilia.