• Aggression;
  • Interference;
  • Macaca mulatto;
  • Control


Rhesus monkeys occasionally break up fights among conspecifics and this phenomenon may be called “interference.” The present study describes the patterns of interference in a group of free-ranging rhesus monkeys and evaluates the effect of this behavior onMacaca mulatta social organization. Data were collected at Cayo Santiago.

Strong sexual differences were found in the patterning of interference behavior. Females tended to help victims of aggression and animals from the interferer's own genealogy, especially juveniles. In addition, females were likely to interfere as subordinate to the target animal. Natal and non-natal males oriented toward unrelated adult females and generally only interfered in fights if dominant to the target animal. Further, the males helped victims of aggression significantly less often than females did. Contrary to expectation, the dominant males were noteworthy neither for the quantity nor the effect of their interference. In general, the findings reinforce the notion that females are the stable and central part of a rhesus monkey social group. The findings also suggest that interference plays a role in the maintenance of group stability and cohesion.