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PRI's Environmental News Magazine

Animal Note

Air Date: Week of October 12, 2001

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Living on Earth's Maggie Villiger reports on newly discovered acoustic turf wars among masked birch caterpillars.

Transcript

CURWOOD: Coming up, keeping an eye on nature from the sky. First, this page from the Animal Notebook, with Maggie Villiger.

VILLIGER: Caterpillars seem to have one single-minded mission: eat, eat, eat. But recently, researchers observing masked birch caterpillars, discovered that they aren't just voracious eaters, they're also staunch defenders of their grazing territory. Here's the scenario: one caterpillar is innocently chomping away on the leaf area around its nest; another masked birth caterpillar approaches. The first begins making sounds that translate roughly to “Back off, this is my turf!” In some cases, the intruder gets in on the action, engaging in a sound duel. The caterpillars drag a special scraping structure across the leaf and pound on it with their mandibles. The heat of the battle sounds like this:

[SOUND OF SCRAPING AND THUMPING]

VILLIGER: There can be a bit of head butting, but never biting. And then, the showdown is over.

Researchers found that the nest defender won the battle about 85% of the time, though nest takeovers did occur. Masked birch caterpillars don't have ears that can pick up sound vibrations in the air. They sense the territorial signals as vibrations on the leaf. Scientists are now trying to figure out where these vibration receptors are located in the caterpillars. They also wonder whether other specifies use the same kinds of techniques to say “Private property, get lost.” That's this week's Animal Note, I'm Maggie Villiger.

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

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