Predictors of Long-Term Social Compatibility in Rhesus Macaques (Macaca mulatta) Housed in Research Settings

Social housing improves the well-being of monkeys in research settings; however, little is known about factors influencing the long-term stability of established, full-contact pairs. Archival data were examined to determine whether sex, age, weight, duration pair housed, familiarity, social interruptions, room changes, or sedation events predicted eventual separation of pairs for social incompatibility (n = 80) or for nonsocial reasons (e.g., research or health needs) (n = 1143). Using a logistic regression model (Wald Χ²(8) = 42.325, p < .001), three significant factors were identified. Pairs in which partners had known prior familiarity in group housing were less likely to experience social incompatibility (p = .034). Pairs housed together longer (p < .001) and who staff had temporarily separated through the placement of a cage divider to reduce physical contact were more likely to require permanent separation for social incompatibility (p < .001); additional analysis revealed that dividers were often placed for social reasons, suggesting early signs of social instability. Findings may be useful for primate caregivers when making decisions about managing social partners.