[9, 22 and 23]) and Trichostatin A molecular weight once elevated stress levels have subsided. Previous work on intergroup conflict has shown that losing groups might be prevented from using certain areas because of exclusion by winners [9 and 23] or may avoid areas of agonistic interaction if prior experience reliably predicts future conflict [22]. This reduced involvement in agonistic interactions parallels the “loser effect” often found in dyadic contests, whereby individuals become less likely to escalate future conflicts following a defeat (reviewed in [24]). Even where loser effects are not found, previous fights can reduce aggression and discourage home-range overlap [25 and 26]. Here, however, we found the opposite

effect: the woodhoopoe groups in our study used roosts in zones of conflict more often following intergroup conflicts, especially conflicts that were lost, and arrived at roost sites earlier on such occasions. This greater usage may represent defense of a limiting resource; as in many other species [ 23, 27 and 28], there is a risk that highly productive or important parts of a territory will be annexed by successful rival groups [ 29]. Despite this risk, groups may continue to use other roosts outside the zone of conflict if they provide greater thermoregulatory benefits [ 13], provide more protection from predators

[ 29], or are less likely BMS354825 to accumulate water on rainy nights [ 30], or if switching roosts is important for minimizing the buildup of parasites [ 31]. Occasions when members of the same group roost in different

places probably reflect unresolved between-individual conflicts of interest over group decisions [32 and 33]. Our results suggest that an earlier conflict with a rival group enhances the likelihood that a consensus will be reached later on, i.e., that all group members roost together. Since all adult woodhoopoe group members contribute Rucaparib to the majority of IGIs [1] and the outcome of extended IGIs is strongly determined by relative group size [15], an increased need for collective defense may override within-group disagreements about roost site. Previous work on the factors influencing group fissions has focused on environmental variability and uncertainty, as well as within-group factors such as individual energetic state, the social relationships between group members, and the ways in which information is gathered and shared [34, 35 and 36]. Our study suggests that external factors—in this case, intergroup conflict—also play an important role and should be considered in future work on consensus decision-making. Extended intergroup conflicts appear to cause short-term increases in stress, which may be responsible for previously documented changes in allopreening and other behavior in the immediate aftermath [7 and 37].