Cluck cluck cluck! I found us potluck!

Imagine you are on a hunt for food and then jackpot! But do you take all the food for yourself or do you call your friends and family to share the food? Well for several animals, when they find food, they make a specific sound for their community to be aware that they have found food in their respected location. When male chickens discover food, they produce a “food call” and usually do it in the presence of a hen. This tells us that food calling is dependent on food along with social context because hens respond with their anticipation of a feeding opportunity. The male food call is not only associated with food quality, but also with the rate at which they perform an instrumental task to obtain that food; this may suggest that the calls may reflect some aspect of the male chicken’s motivational state. Males perform a “tidbitting” display where they pick up the food and drop it repeatedly, with a vertical movement of the head and neck. Hens then approach the male and take the food either from the substrate or directly from between the male’s mandible.

The signal the male produces is sufficient for the proper response from the receiver, even in the absence of contextual cues, which can be provided by the non-vocal behavior correlating to signalling. This study further explored the chicken food calls to determine whether the signals meet the criteria for functional reference. There were two playback experiments to assess the hens’ responses to food calls, in the absence of any other cues.

The first experiment was when food calls and ground alarm calls (both short pulsatile sounds that are produced in long bouts) were both presented. Food calls are given by males when food is found, while ground alarm calls are given by witnessing approaching predators. The second experiment then compared effects of food and the calls, under similar social circumstances. 22 Adult golden Sebright bantam hens were used because they were not used for artificial selection.  The hens were placed in a large room with windows, and a male was placed with each hen. The experiment was conducted in a sound attenuating chamber with “Sonex” foam baffles (to avoid echo), artificial grass covering the floor (to reduce movement noise and provide comfort for hens’ walking), and an opaque black fabric covering the wires (to avoid visual cues of the sound speaker).

Experiment 1: Each hen experienced all stimulus conditions (food call–ground alarm call or ground alarm call–food call) in separate test sessions, where each of the 22 hens were randomly assigned one of pairs of calls. The test began 15 minutes after the hen was placed in the cage, and the stimulus sound was presented by extending from 2 minutes pre-stimulus until 3 min post-stimulus. Food calls evoked an anticipatory feeding behaviour (looking downwards and pecking at the substrate), both during the stimulus and in the post-stimulus period, while ground alarm calls did not. However, both calls evoked a social responses such as contact calling, orienting responses, and increased activity.       

Experiment 2: The gap time between experiment 1 and 2 was 10 weeks. Food calls and ground alarm calls were screened in the same way as experiment 1. Some recordings had to be eliminated before taking into consideration because the bouts of calling were either too brief or the signal-to-noise ratio was lower than that of food calls. Therefore two male bout calls were selected, in addition to two new food call recordings (not being used in experiment 1). Both types of calls evoked a contact calling and orienting towards the loudspeaker, but only food calls increased the probability of looking downwards.  The results suggest that food calls affect feeding behaviour specifically and the responses of hens were not simply attributable to the simulated presence of a nonaggressive conspecific companion.

The overall findings is that food calls are sufficient to stimulate feeding behaviors in the hens receiving them. The rate at which they inspected the substrate increased, as they moved their heads close to the ground, even if no food was present. There are two specific reasons for these responses. The increase in looking downwards was evoked by the food calls not by either the ground alarm calls (Exp.1) or contact calls (Exp. 2). Another is that playback of food calls affected looking down selectively as changes in looking down were not associated with social behavior.

Along with other animals, chickens have the ability to produce various calls such as having alarm calls for terrestrial predators, for aerial predators, and for food findings. This experiment shows that chickens have the ability to monitor their environment and respond accordingly.  They have a strong relationship between their visual system and behavioral responses. Being a hen is easy then, as all they have to do is hear out for a male calling and wallah, food is there!                     

Evans, C. S., & Evans, L. (1999). Chicken food calls are functionally referential. Animal Behaviour,58(2), 307-319. doi:10.1006/anbe.1999.1143