Social information use in the wild jackdaw, Corvus monedula

Abstract

From insects to great apes, animals use information from others to assess their environments and improve decision-making. Social information can be essential in collective decisions - producing cohesive behaviour where individuals monitor each other’s cues - and can facilitate learning of adaptive information, allowing individuals to avoid costly trial and error. Social information use is gaining growing attention, but there is a lack of experimental manipulation, especially in studies of wild animals. I address both collective decision making and social learning in wild jackdaws using playback experiments. Jackdaw roosts can contain thousands of birds, yet morning departures are coordinated and cohesive. While jackdaws are very vocal in the pre-departure period, it is unclear whether these vocalisations help coordinate roost departures. Using a playback experiment, I explored whether low frequency calls act as ‘primers’ in collective roost departures. I gave playbacks of high or low frequency calls to jackdaw roosts at dawn, predicting that low frequency calls would result in earlier roost departure. I found no effect of playback type on the time of roost departures, and no support for my hypothesis that low frequency calls act as ‘primers’. It is thought that jackdaw chicks are born naïve to threats, learning to recognise predators through observing conspecifics. However, it is unknown whether this is limited to fledged birds, or altricial young begin learning about threats in the nest. Using playbacks, I explored whether nestlings learn to recognise novel predators after receiving calls in association with adult jackdaw scolds. I found a change in chick behaviour after training, most notably reduced vigilance after training with contact calls, compared to both untrained and scold-trained chicks, suggesting that they had learnt to recognise the stimulus as unthreatening.