Deconstructing a multimodal signal: Assessing the efficacy of the visual and vocal components of a food-related call

Food calling is widespread in social birds and primates. In Gallinaceous birds, these vocal signals often occur simultaneously with a visual display. Few studies have systematically examined how multiple display components alter signal efficacy. In this study, we used male golden Sebright chicken's tidbitting and food calling displays to investigate the impact of the two components on food search behavior. We conducted playbacks using high-definition video recordings on plasma display screens and audio recordings to assess the reactions of conspecific females to Multiomodal, Video Only, Audio Only and Control conditions. The audio component had the greatest impact on female's food search behavior. In Audio Only, latency to food search was shortest and total search time was greater than in the Visual Only. However, when compared to Multimodal, while latency was still shorter, total time searching was not significantly different. Using current theoretical models, the behavior could be classified either as enhancement or as redundant signals with equivalent effects. This suggests the needs for further development of the current theoretical models.