Sex Ratio, Conflict Dynamics, and Wounding in Rhesus Macaques (Macaca mulatta).

Area of Science:

• Primate behavior
• Animal sociology
• Primate conservation

Background:

• Primate social groups often feature multi-male, multi-female structures with a female dominance.
• The role of sex ratio in primate group stability is debated, with potential impacts on mate competition and conflict management.

Purpose of the Study:

• To investigate the relationship between sex ratio, male intervention behavior, and trauma incidence in captive rhesus macaque groups.
• To determine how male social dynamics influence group stability and welfare.

Main Methods:

• Observational study of seven captive rhesus macaque groups.
• Quantification of sex ratio, male intervention frequency and success, and trauma rates requiring veterinary care.
• Analysis of male relatedness to dominant matrilines.

Main Results:

• High-ranking adult males intervened more frequently and successfully than females in conflicts.
• Intervention success and reduced trauma rates were associated with lower female-to-male ratios, specifically when males were unrelated to dominant matrilines.
• Groups with a lower proportion of females per unrelated male showed better conflict management and fewer injuries.

Conclusions:

• Male conflict management behavior, particularly by unrelated males, is a key factor linking sex ratio to group stability and reduced trauma.
• Managing sex ratios in captive primate groups is crucial for predicting and ensuring group stability and welfare.