Do chimpanzee food calls bias listeners toward novel items?

Social learning is beneficial in almost every domain of a social animal's life, but it is particularly important in the context of predation and foraging. In both contexts, social animals tend to produce acoustically distinct vocalizations, alarms, and food calls, which have remained somewhat of an evolutionary conundrum as they appear to be costly for the signaller. Here, we investigated the hypothesis that food calls function to direct others toward novel food items, using a playback experiment on a group of chimpanzees. We showed chimpanzees novel (plausibly edible) items while simultaneously playing either conspecific food calls or acoustically similar greeting calls as a control. We found that individuals responded by staying longer near items previously associated with food calls even in the absence of these vocalizations, and peered more at these items compared with the control items, provided no conspecifics were nearby. We also found that once chimpanzees had access to both item types, they interacted more with the one previously associated with food calls than the control items. However, we found no evidence of social learning per se. Given these effects, we propose that food calls may gate and thus facilitate social learning by directing listeners' attention to new feeding opportunities, which if integrated with additional cues could ultimately lead to new food preferences within social groups.

Social learning about construction behaviour via an artefact.

One source of public information may be the enduring products of others' behaviour, such as discarded tools or vacated nests. Here, we examined whether observation of a nest affects the material captive zebra finch males prefer when they construct their first nest. It does: for first-time nest construction, males that viewed only an empty cage preferred the colour of material each initially favoured but those males that had observed a pre-built nest of material of their non-preferred colour lost their material-colour preference altogether. Additionally, half of the males that viewed a nest were tested in an environment (the laboratory) different to that in which they were reared (an outdoor aviary). We had expected the aviary-reared (versus laboratory-reared) males would be more uncertain, and thus more likely to select material for their first nest that matched in colour to the colour of the 'demonstrated' nest-but this was not the case. The aviary-reared males did, however, tend to touch first the demonstrated colour of material more than did the laboratory-reared males. Together these results show that both observation of a nest and a change in environment can influence the material choices of novice builders. For naïve animal builders, then, construction artefacts can be information resources for learning about potential construction material.