Food-associated calls as public information about patch quality

Several species of avian and mammalian social foragers vocalize after locating food. Empirical work has shown that such food-associated calls can be detrimental to the caller because other group members are often attracted to the discovered food. Individuals can obtain anti-predator benefits from emitting food calls if group size increases in response to the vocalization but empirical work has shown that food calls also are emitted by individuals in groups of fixed size ; in such groups, the benefit of emitting food calls is less obvious. Here, I extend earlier work and propose that food-associated calls may represent auditory public information about food patch quality. Food calls thus function to provide patch quality information to other group members. Such information benefits individuals because it allows social foragers in groups of fixed size to exploit resource patches more efficiently by preventing early departures from rich resource patches. The hypothesis that food-associated calls represent auditory patch quality information makes several predictions about the likelihood that foragers will emit a food call in response to food discovery. In particular, this hypothesis predicts that foragers who : 1) are not in visual contact with other group members, 2) do not initiate group movements, or 3) are hungry, should be most likely to give food-associated calls. Empirical evidence to test these predictions is sparse but generally supports these predictions.