Factors affecting aggression among females in captive groups of rhesus macaques (Macaca mulatta)

Brianne Beisner, Lynne A. Isbell

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Captive groups of primates often exhibit higher rates of aggression than wild, free-ranging groups. It is important to determine which factors influence aggression in captivity because aggression, particularly intense aggression, can be harmful to animal health and well-being. In this study, we investigated the effect of ground substrate as well as season, rank, age, and group size on rates of agonistic interactions per female in seven captive groups of rhesus macaques (n = 70 females, 1,723 focal samples) at the California National Primate Research Center. Agonistic interactions were divided into three categories: displacements, mild aggression, and intense aggression. Females living in enclosures with gravel substrate were 1.7 times more likely to be involved in intense aggression (e.g. chases and physical contact) than females living in enclosures with grass (Poisson regression model: P<0.001). High-ranking females were at least 1.3 times more likely to be involved in mild (e.g. threats and lunges) aggression than lower-ranking females (low rank: P = 0.03; mid rank: P = 0.001). Females of all ranks were 1.5-1.9 times more likely to be involved in both intense and mild aggression during the breeding season than other seasons. Age and group size did not affect rates of mild or intense aggression. These findings indicate that although some aggression appears to be natural and unavoidable, i.e. aggression during the breeding season, the well-being of captive macaques can be improved by developing grass substrate in outdoor enclosures.

Original languageEnglish (US)
Pages (from-to)1152-1159
Number of pages8
JournalAmerican Journal of Primatology
Issue number11
StatePublished - Nov 1 2011


  • Aggression
  • Colony management
  • Dominance rank
  • Ground substrate
  • Welfare

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Animal Science and Zoology


Dive into the research topics of 'Factors affecting aggression among females in captive groups of rhesus macaques (Macaca mulatta)'. Together they form a unique fingerprint.

Cite this