Advertised quality and resource value affect aggression and social vigilance in paper wasp contests

Animals frequently compete over limited resources such as food, territories or mating opportunities. Contest behaviour varies based on factors such as the value of the contested resources and the agonistic ability of rivals. Much work on animal contests has examined aggression, but vigilance, or a state of heightened alertness directed towards specific stimuli, may also be an important component of competition in many species. In this study, we measure the relationships among social vigilance, aggression, agonistic ability and resource value during staged contests over nest ownership in Polistes dominula nest-founding wasps. Our results show that both social vigilance and aggression are involved in mediating social risk during contests. Nest owner vigilance towards a rival increased with the time of season, a measure of nest value. Owner vigilance was also positively associated with aggression such that more aggressive owners were more vigilant. During contests, aggression of owners and rivals was influenced by different factors. Owner aggression was positively associated with nest size, another measure of nest value, while rival aggression was unrelated to nest size. Instead, rival aggression was associated with facial patterns that function as signals of agonistic ability; rivals were less aggressive to owners that signalled high agonistic ability than they were to owners that signalled low agonistic ability. The distinct predictors of contest behaviour between owners and rivals indicate that competitive role has a surprisingly strong influence on cues used to inform contest behaviour. Differences may occur because owners and rivals have different information and/or motivation. These results also suggest that social vigilance and aggression may be complementary behaviours that animals use to mitigate social threat.