Air Date: Week of June 28, 2002

Living on Earth’s Maggie Villiger reports on the discovery that frogs use audio cues to flee fire.

Transcript

CURWOOD: Coming up, greening the city. First, this page from the Animal Notebook with Maggie Villiger.

[MUSIC UP AND UNDER]

VILLIGER: When fire approaches, most animals flee or try to seek shelter. Scientists assume visual cues, the smell of smoke or perhaps the heat of the fire tell an animal to head for safety. All these warning signs are useful over relatively short distances, and work best for large animals that are able to move fast and far.

But researchers knew that a small amphibian called the Reed Frog can also detect the threat of fire. And they suspected another sense might be involved. So the scientists snuck up on individual frogs as they rested in the midday sun of the West African Savannah, and played them recordings of fire. Here’s what the frogs heard.

[SOUND OF CRACKLING FIRE]

VILLIGER: This sound effect was like a blaring fire alarm for the Reed Frogs. Right away, they would lift their heads, scan their surroundings, and start hopping toward a tall tree or dense bushes, whatever would be the closest refuge.

A few months later, toward the end of the dry season, scientists repeated the experiment and discovered frogs were now less likely to flee the sound of fire. They think it’s because by the end of the dry season, the frogs are extremely weak. Any action that expends extra energy, such as hopping into a tree, means almost certain death for the frogs.

Researchers are now investigating what influences a frog’s choice whether to run from fire or stay put and take his chances. That’s this week’s Animal Note. I’m Maggie Villiger.

[MUSIC UNDER]

CURWOOD: And you’re listening to Living on Earth.

[MUSIC: BILL FRISELL, "LONESOME," RARUM, ECM, 2002]