Two Methods of Social Separation for Paired Adolescent Male Rhesus Macaques (Macaca mulatta)

Abstract

Literature-based recommendations regarding how to separate pairs of laboratory-housed NHP when required for research, veterinary, or management needs are unavailable. This study assessed 2 separation techniques-rapid and stepwise-to determine whether a period of limited social access mitigates the behavioral stress response after complete separation. Researchers observed 12 pairs of mother-reared, adolescent male rhesus macaques before and after separation with a solid divider; 6 of the pairs experienced a transitional week of limited social access through a perforated panel. Observers collected 30-min focal animal scans during study phase, totaling 144 h of behavioral data. Target behaviors included those classified as protest, agitation, tension, and withdrawn or self-directed. Social separation resulted in a significant change in behavior. Separated monkeys displayed more withdrawn or self-directed behaviors (for example, huddling, self-directed stereotypies) than when pair-housed. Stepwise separation resulted in increased agitation behaviors in the limited contact phase and did not mitigate separation effects. Adverse behavioral changes during the limited contact phase support continuous pair housing until required individual housing.

Figure 1.

Operational definitions of disturbance behaviors.

Figure 2.

Percentages (mean ± SE) of time that disturbance behaviors were observed across separation phases in the rapid and stepwise separation techniques. (A) Withdrawn or self-directed behaviors. (B) Agitation behaviors. (C) Tension behaviors. (D) Protest behaviors.