Often, when you visit a farm or a chicken coop, there is no way to avoid the incessant clucking of chickens scrabbling around. It seems to be non-stop, with very little purpose. However, a study conducted in 1999 investigated the vocalizations of chickens and their effects on food localization. Comparable to vervet monkey calls which alert others to specific predators nearby, chickens’ vocalizations entail important information about where to find food.
Christopher Evans and his colleague, Linda Evans, developed two experiments in an effort to uncover the types of information encoded in the seemingly annoying chicken clucks. The two experiments involved the playback of two different types of calls: male food-associated calls and ground alarm calls which warn about a nearby predator in the first study and food calls and contact calls in the second study. Contact calls are used to merely communicate non-specific information. Twenty-two hens were allowed 15 minutes to explore the test coop, which was largely similar to normal farm chicken coops. Once the hens were adjusted to their new environment, Evans and Evans played one of the calls for approximately 20 seconds each. The researchers measured the chickens’ behaviour for 60 second before the call was played and 60 seconds after the call was played. What they found was that the food-associated calls prompted the hens to look down towards the ground and begin pecking at the substrate. However, the ground alarm calls did not elicit this response and only increased activity. Food-associated calls also led to the chickens being more likely to distance themselves from the origin, in comparison to ground alarm calls.
In the second experiment, the hens were exposed to food-associated calls and contact calls. In this study, the chickens responded to the contact calls, but only the food-associated calls again elicited looking downward. This is a particularly interesting finding because contact calls, in natural environments, are often elicited in similar situations as food-associated calls.
While this study does not fully address predator alarm calls in chickens (it left out aerial alarm calls) and was conducted in a laboratory, Evans and Evans found some unique information regarding chicken calls and what referential behaviours they elicit. This study speaks to the fact that these calls in chicken are functional behaviourally referential, which is the first such discovery in the natural animal world – at publication of the article. This means that the referential vocal signals can encode a variety of information to other chickens. Through their research, Evans and Evans have thrown the door wide open regarding information-encoded calls related to food, and suggest future studies examine how this related to the positioning of chickens’ eyes which are on the sides of their head.
Evans, C. S., & Evans, L. (1999). Chicken food calls are functionally referential. Animal Behaviour, 58, 307-319. doi: 10.1006/anbe.1999.1143
