Who cares? Behavioural consequences of social disruptions in redfronted lemurs, Eulemur rufifrons.

Animal groups regularly lose group members as a result of death and dispersal, but the consequences of such a loss on the social relationships among the remaining group members remain generally understudied. Moreover, some of the few studies on this topic reported destabilizing effects of group member loss in some species, whereas in other species individuals apparently compensated for lost partners by strengthening remaining relationships. However, it remains unknown what may drive these contrasting effects in different species. Here, we investigated the impact of the loss of an individual on subsequent social patterns in a basal group-living primate, the redfronted lemur. Using focal animal observation data surrounding 16 disappearance events (five dispersals and 11 predation events) in four groups of wild redfronted lemurs, we tested for changes in the coefficient of variation of relationship strength in affiliative interaction networks, as well as for changes in affiliative and agonistic interaction rates. We found no evidence for significant changes in any of the three measures, indicating that the disappearance of a group member is not reflected by a change in social interactions among redfronted lemurs. Yet, the fact that rates of social interactions did not change significantly indicates that they compensated for the loss of a group member by redistributing their social behaviour towards other individuals. Our study therefore indicates that redfronted lemurs' social interactions are resilient to group member loss. Alternatively, the number of unpredictable disappearance events in our retrospective study may have been too small to detect any effects, underscoring the need for additional comparative research on this topic to determine whether methodological constraints or particular coping mechanisms underly this apparent contrast with anthropoid primates. • First study on influence of group member loss in a strepsirrhine primate. • Disappearance of a group member had no effect on social network measures. • Disappearance of a group member did not affect affiliative and agonistic behaviour. [ABSTRACT FROM AUTHOR]