Progress Understanding Chickens

Helps shed some light on the broiler underworld:

A chicken going "tck, tck, tck" as it pecks is announcing the presence of food. That clucking makes the chicken the first animal other than primates that's been shown to make sounds that, like words, represent something in the environment, researchers say.

... The old tests, however, left a nagging possibility that the clucks just trigger a reflex to search for food, Evans says. Now, he and Linda Evans, also of Macquarie University, have used a different approach that's "given us confidence," he says, to label the chicken clucks as representational signals.

... For the new tests, the Evanses went back to food calls. For example, males go "tck, tck, tck" upon discovering anything edible.... Hens then stalk over to investigate. They take a tidbit from a male's beak or stare intently at the ground. "They look like people who've lost their glasses," says Chris Evans.

In half the tests, the researchers scattered a few kernels of corn onto the floor. That's enough food for a hen to notice, but nowhere near enough to satisfy its craving. The hens ate the corn before hearing a male's clucks. In the other half of the tests, hens encountered no food.

After each hen heard a recording of a male's food call, those that had already received corn spent less than 3 seconds peering at the ground. But birds that hadn't been fed searched, on average, for 7.5 seconds.

The difference in response times reflected whether a bird already knew that food was available, so the call isn't an automatic trigger for some reflex to search the ground, the researchers argue. In contrast, a rooster's ground-intruder call didn't evoke different responses from the fed and unfed groups, the Evanses say in a paper available online and in an upcoming Biology Letters.