You're listening to Shortwave from NPR.

Today, a scientist who found herself in the middle of a disturbing scientific mystery.

It's the early 1990s, and Karen Lips is a graduate student studying frogs in the mountains

of Costa Rica.

And I had set up camp in this little shack that had no running water or electricity.

So this is in Old Growth Oak Forest.

It's cloud forest, so it's moist, and there's moss everywhere.

And amphibians love it.

Karen lived alone, spending her days studying the reproductive behavior of Isma-Hila

Calypza, a tiny tree frog, the color of emeralds.

And then, a couple years into her research, Karen found some dead frogs.

Seven.

Seven is not very much.

She wasn't too worried about it, but she couldn't figure out why they died.

So she sent the frogs off for essentially a frog autopsy.

Then she headed home for Christmas break.

And when I got back, I expected to see the beginning of the rainy season, which is usually

when you see the greatest number of frogs.

And I kept waiting and waiting, and the rains came, and there just weren't very many frogs

at all.

And so I started questioning myself, like, well, maybe I disturbed them.

Maybe the flashlight for two years, one little flashlight, you know, bothered them, and

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