The early 2000s were a great time to study amphibians in Panama. At night, dozens of species sang out in chorus while researchers measured and photographed frog after frog, often hiking to remote sites hours from the nearest road. Jamie Voyles and Cori Richards-Zawacki were both graduate students at the time, just at the start of their scientific careers, and Panama's amphibians offered a plethora of research possibilities.

There were glass frogs with transparent skin, nocturnal frogs with bulging eyes, and arboreal frogs with huge, webbed feet.

"The places where we were working had some of the most amazing amphibian diversity in the world. If you went out at night you'd see and hear dozens and dozens of different species every night, some of them amazingly beautiful," Richards-Zawacki says.

Within a few years, everything changed. The amphibian choir grew softer, more muted, and species that had once been plentiful started vanishing.