Smithsonian researchers in Panama have begun to reintroduce native golden frogs to the wild in special enclosures
Panamanian golden frog in nature Brian Gratwicke / NZCBI
The last known time that someone saw bright yellow frogs bespeckled with black dots in Panama’s wilderness was in 2009. These Panamanian golden frogs probably succumbed to a fungal disease called chytridiomycosis, which has decimated amphibian populations across the globe.
Now, researchers who have captive-bred the critically endangered golden frogs recently soft-released 100 of them into nature. The creatures stayed in special pens in late 2025 so that the scientists could assess how the deadly disease affects the animals—and how they might eventually adapt to it.
“This project was designed to see what would happen if we put these golden frogs back into a wild situation, just to kind of understand what are the disease dynamics, and how do these frogs regain their skin toxins,” Brian Gratwicke, a conservation biologist at the Smithsonian’s National Zoo and Conservation Biology Institute (NZCBI), tells Smithsonian magazine.
Chytridiomycosis is an infectious disease caused by the fungus Batrachochytrium dendrobatidis, or Bd, also called chytrid fungus. It’s thought to have reached southern Central America—where Panama is located—in the late 1980s. In 2019, researchers estimated that Bd had led to the extinction of 90 species worldwide as well as the decline of at least 491 others, and chytridiomycosis is often considered the most devastating wildlife disease on record.
Fungal spores can travel in water and even catch rides with other animals, including humans. Once they reach an amphibian, chytrid fungus can have devastating effects.
“It attacks the skin and kind of forms the ability to grow in and on the skin, and then causes, usually, the skin to fall off of the animal,” Jason Stajich, a microbiologist at the University of California, Riverside, who is not involved in the Panama project, tells Smithsonian magazine. “Because amphibians breathe through their skin, that can really impair them.”
Fun facts: Deceptive, deadly frog
- Despite their name, Panamanian golden frogs are actually toads.
- Research suggests that each frog has enough toxins in its skin to kill more than 1,000 mice.
Around two decades ago, experts at NZCBI and the Smithsonian Tropical Research Institute predicted the decline of golden frogs and other creatures in Panama based on how Bd was spreading. So, they partnered with the Cheyenne Mountain Zoo and Zoo New England to build the Panama Amphibian Rescue and Conservation Project (PARC) to protect animals at the highest risk of extinction from the fungal disease.
Gratwicke and his colleagues at PARC have been captive-breeding these amphibians for about 20 years. Now, the team has begun to release them back into nature to understand how to rewild these threatened species. In August 2025, the researchers put golden frogs in pens called mesocosms, which Gratwicke likens to outdoor patios.
“We put a big layer of leaf litter on the bottom that’s full of little insects and food so the frogs can forage,” he says. “It keeps the frogs inside where we can find them again, and it also keeps some of the predators out.”
The frogs spent 12 weeks inside these mesocosms, while researchers kept tabs on the creatures. During that time, about 70 percent of the frogs died from chytridiomycosis. Most of the surviving frogs were fully released into the wild afterwards.
Although the death rate was high, the data collected during this trial period is crucial to understanding how chytridiomycosis spreads and persists, and how amphibians might be able to adapt to chytrid fungus, Gratwicke says. “This experiment is probably the first experiment where we’ve actually been able to really get a full understanding of the disease dynamics of these animals.”
This might help researchers eventually place golden frogs in environments that are at adequate temperatures for the animals but too hot for the fungus. In recent research, for example, individuals of a frog species that lives in southeastern Australia seemed to have an easier time fending off chytrid fungus if they spent time in warm, sunny “saunas” than those in cooler temperatures.
And in some regions, amphibians whose numbers declined due to chytrid are beginning to bounce back. Tom Smith, a biologist at the University of California, Santa Barbara, has seen this happen with certain frogs in the Sierra Nevada mountains in California. “These populations have now been living with that pathogen for several generations across several decades, and we’re actually seeing adaptation and evolution to that in some of the populations,” he tells Smithsonian magazine.
Additionally, some frog species in the region do not seem to be susceptible to chytrid fungus, and scientists hope to use those species to “discover what the mechanism of tolerance and or resistance is to the disease,” says Smith, who is not involved in the Panama project.
For now, the team at PARC will continue to keep an eye on the Panamanian golden frogs to better understand fungal resilience in the creatures.
“I’ve been very pleased with the progress,” Gratwicke says. “It’s really important to actually make progress towards our ultimate goal, which is to create healthy, thriving populations of these animals to the wild. This experiment is one of the first steps towards achieving that.”
One of the links had another great photo of one: Panamanian Golden Frog, but actually a toad
Panamanian Golden Frogs Disappeared From the Wild Due to a Deadly Fungus. Now, Scientists Are Returning Them to Nature
Submitted 23 hours ago by cm0002@lemmings.world to science@mander.xyz
