Edgardo Griffith, EVACC’s director, stands on a rock in the middle of the Rio Maria, in the cloud forests about a 30- minute drive from the valley floor. If an art director were to set-design Eden, it would look like this place. Not far upstream, water slides down a broad rock face. To the left, two smaller waterfalls send arcs of foam into glassy pools. Moss, ferns, and epiphytes, as well as orchids and bromeliads, cling to every surface. Hanging vines festoon the trees. Heliconias climb like red ladders up through the mist and toward the canopy more than 100 feet above, where a few late-afternoon shafts of light lance down like golden fingers. Griffith leans on the snake hook that serves as his walking stick, amphibian probe, and tool of defense. Then, he closes his eyes to the over-the-top scenery and listens. But the only things to hear are the river and the breeze rustling the leaves above. Just a year ago, this high, mist-cooled jungle supported a diverse, cacophonous ecosystem. Today, it’s silent.

When Griffith opens his eyes, there’s a deep sadness there. “Now when you go to the forest, it’s like watching a movie without the sound,” he says with a sigh.

The silence follows an exotic fungus that, when it attacks, kills 80 percent of the amphibians in its path. It is a fungus that has spread to every continent but Antarctica. “Frogs are a big part of the web of life,” Griffith explains. “As soon as you take the frogs out, things start crashing. Forests go silent.”

have worried about declining frog populations for several decades. Today, it is estimated that 33 percent of the 6,000 described frog species are threatened with extinction, and many experts believe the number may even be as high as 50 percent. And that doesn’t count the 5,000 species that are thought to be out there but have not yet been discovered. If these predictions turn out to be true, this could be the biggest mass extinction of a class of animals since the dinosaurs left the scene.

Over the years, studies have linked many of the usual suspects -- pollution, habitat loss, climate change -- to what has come to be called the global amphibian crisis. But about a decade ago, studies from researchers around the world began to prove that a killer fungus was a major contributor to frog decline. Then, four years ago, a study appeared that tracked and described the advance of the pathogen in Central America. It, and the sheer number of frogs at risk from all threats, in turn, inspired the 2006 launch of Amphibian Ark, a worldwide coalition of zoos, universities, and nonprofits that want to take preemptive action.

“Unlike other extinctions, the frog story is different in scope: so many species and happening everywhere,” explains Karen Lips, a professor of zoology at Southern Illinois University Carbondale, who wrote the study that tracked the fungus.