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A. Boosting the Effectiveness of a Crop Protection Device

Narrator: This is Science Today. Researchers at the University of California , Davis have developed an electronic unit that plays audio recordings of crow distress calls to prevent the birds from causing extensive damage to almond crops. Staff research associate Paul Gorenzel says crow behavior is what makes the device particularly effective.

Gorenzel: Crows have quite an elaborate vocabulary. They have a number of calls that have actual meaning to them. In one particular is called "the death cry of the crow." It's probably a crow that's in the grasp of a predator, it's screaming.

Narrator: This recording would warn other crows to keep away. The device has four different distress calls and Gorenzel says it's important to rotate them.

Gorenzel: Birds eventually habituate to almost anything. That was the idea of having the calls change. It would be something new, it wouldn't be the same call repeating over and over again. We would change it after so many days to a second, third, fourth call. And hopefully that would delay the onset of habituation.

Narrator: For Science Today, this is Larissa Branin.