Report Conflict between Groups Promotes Later Defense of a Critical Resource in a Cooperatively Breeding Bird

Summary Conflict between groups (intergroup conflict) is common in many social species Results Green woodhoopoes (Phoeniculus purpureus) live in groups consisting of a dominant breeding pair and up to six nonbreeding helpers of both sexes Interactions between groups are common and involve all group members contributing to alternating choruses (or ''rallies'') [1], which on rare occasions escalate to physical fighting Woodhoopoe IGIs are highly variable in duration (1-45 min) and exhibit a bimodal distribution: ''short'' IGIs (>57% of cases), usually on territory boundaries, are decided within 5 min and primarily involve information exchange about current group structure and potential breeding opportunities, while ''extended'' IGIs (w30% of cases), which develop when there is a conflict over territory space, take >15 min to resolve and usually involve a territorial intrusion Despite no evidence of prolonged stress, and despite groups always (100% of 134 cases) moving away from the IGI site in the interim, the occurrence and type of IGIs in the morning (none, short IGI, extended IGI) significantly influenced the likelihood of roosting within a zone of conflict at the end of the day (generalized linear mixed model [GLMM]: c 2 2 = 23.30, n = 232, p < 0.001). Specifically, zone-of-conflict roosts were more likely to be chosen on evenings when there had been an extended IGI that morning compared to on evenings when there had been a short IGI or no IGI that morning