Reconciliation and post-conflict behaviour in ringtailed lemurs, Lemur catta and redfronted lemurs, Eulemur fulvus rufus

Sociality always entails some form of intra-group competition for food or other limited resources and so increases the probability of conflict between individuals. Within groups, non-dispersive modes of coping with competition and its consequences may evolve. External factors, such as predation risks or the ability to defend resources against other groups may select for the same outcome. The study of Lemuriformes can provide such comparative date. Lemurs form an independent primate radiation and represent the most primitive group-living primates. Also, their social complexity and other aspects of their social structure differ from most anthropoid primates.

 

Two ring-tailed lemurs showing aggresion toward one another.

Two ring-tailed lemurs and two red-fronted lemurs that have occupied large natural-habitat enclosures at Duke University for several years were used at subjects for this study. Their daily diet is supplemented by fruit or monkey chow, along with their natural foods they eat. They are used to humans observing them, and are each individually identified by special neck collars. The fence that separated the two species groups was removed, and the resulted deaths and animal removals for L. catta was between 12 and 26, and for E. fulvus between 5 and 11. The victims were all ages and sex classes.

For the observations, the lemurs were characterized as only aggressive (A), only submissive (S), both aggressive and submissive (AS), or no agonistic behavior (O). First recorded was several details of each agonistic interaction, second recorded was the intensity of each conflict, using a simple scale of 1 to 5 (1 being low and 5 being high). Lastly recorded was the identity of the individuals.

Red-Fronted Lemurs

Agonistic interactions may affect the absolute frequency of subsequent interactions, their relative timing, or both. Several methods for demonstrating reconciliation are available, the most common employing a specific matched-control period, usually the same time on the following day for each post-conflict period. One can determine whether affinitive contact occurred earlier or exclusively in the post-conflict period, compared to the respective matched-control period. The following were the results of the conflicts.

 

In the matter of L. catta, the results indicate that only 9 of the 125 conflicts were followed by at least one affinitive interaction between former opponents. Contrastingly, affinitive interactions between former adversaries were observed in 15 of the 125 recorded. These results indicate that there is a strong trend toward a decreased possibility of affinitive contact between former opponents after a conflict. For E. fulvus, agonistic interactions between them had a more positive effect, and had a significant effect on subsequent behavior because of affinitive interactions between former opponents occurred significantly earlier following a conflict. The following table indicates the number of opponents who reconciled.


The most important conclusion of this study is the lack of evidence for an increase in post-conflict affinitive interaction between former opponents in ringtailed lemurs. Also, the reconciled hierarchy model does not provide a general explanation for the occurrence of reconciliation across species. Reconciliation is not a necessary condition for life in permanent social groups.

      Kappeler, P. (1993) Reconciliation and post-conflict behaviour in ringtailed lemurs, Lemur catta and redfronted lemurs, Eulemur fulvus rufus. Animal Behaviour Volume 45, Issue 5, Pages 901-915