Brief report: Outbreak of severe aggression in captive Macaca mulatta

Area of Science:

• Primate Behavior
• Animal Sociology
• Captive Animal Studies

Background:

• A rhesus macaque (Macaca mulatta) breeding group experienced severe aggression among females.
• This occurred four years after the group's establishment, coinciding with a breeding season marked by increased injuries in other groups.
• This season was notable as it was the first time a significant number of females reached sexual maturity.

Purpose of the Study:

• To investigate the causes of a severe aggression outbreak in a rhesus macaque breeding group.
• To determine the potential link between female sexual maturation and aggression levels in captive primates.

Main Methods:

• Observational study of aggression and injury incidence within rhesus macaque breeding groups.
• Analysis of demographic data, specifically focusing on the maturation status of females within the affected group.

Main Results:

• The group with the most severe aggression had the highest number and proportion of maturing females.
• A significant increase in injured females was observed across multiple breeding groups during the same season.
• Simultaneous maturation of a large cohort of adolescent females appeared correlated with heightened aggression.

Conclusions:

• The simultaneous sexual maturation of numerous adolescent female rhesus macaques may be a significant factor contributing to increased aggression.
• Aspects of captivity may exacerbate these aggression levels in rhesus macaque populations.
• Further research is warranted to explore the specific environmental and social triggers of aggression in captive primates.