The importance of social cues in propagation fronts and other new environments
Résumé
Individuals confronted with novel environments, for instance recently modified environments as towns or recently occupied habitats as colonization fronts, have to cope with a lack of information concerning localization of resources and suitable breeding sites safe from predators. We hypothesized that, under these conditions, a social species like Sturnus vulgaris would be more responsive to social cues indicating food and conspecifics’ presence than individuals belonging to populations established longer in a habitat that they know well. Decoys in feeding postures and a playback displaying a starling chorus allowed us to evaluate their attractiveness level for starlings from towns and propagation fronts. We observed that both kinds of stimuli had more effect on populations in contexts of novelty and that the modalities of response varied qualitatively among populations and depending on the kind of stimulus (visual or acoustic). Our data supported the hypothesis that sensibility to social cues varied according to populations’ history, individuals’ age, and the characteristics of the decoys we used (morphological aspect, group size and interindividual distances). We suggest that these social cues enhance the success of starlings to occupy new habitats.