Nest-founding paper wasps aggregate in "social leks" and decrease aggression during partner selection.

Many animals live in cooperative social groups. The success of social animals is thought to be influenced by both an animal's own characteristics and by the characteristics of its social partners. As a result, some social animals may devote substantial time and energy to assessing potential partners. Here, we study the process of social group formation in Polistes fuscatus paper wasps. Prior to founding nests, wasps engage in extended social partner sampling where they synchronously "shop" for co-foundresses. We quantify wasp behavior during partner sampling using day censuses and recording aggregations. We found that wasps preferentially aggregated at specific locations, without resources or nests, consistent with the formation of a "social lek." In aggregations, wasps engaged in a range of aggressive interactions. At the beginning of the shopping period, wasps engaged in more intensely aggressive behavior and they observe conspecifics fight. Later in the shopping season, wasps engaged in less aggressive behavior. Overall, P. fuscatus devote substantial time and energy to a period of partner selection prior to nest foundation that is suggestive of lekking.