Locomotive stereotyped behavior in cynomolgus macaques, Macaca fascicularis

Primate infants separated from their mothers and kept alone for a long period may exhibit behavioral disorders and develop stereotyped behavior according to genetic predispositions of the infants and environmental factors such as characteristics of the cage. However, it is not clear whether the locomotive and repetitive stereotyped behaviors are related to maternal separation or isolation rearing early in life. The locomotive and repetitive stereotyped behaviors and their relationship were examined with 65 juveniles of cynomolgus macaques kept under artificial conditions. All infants were separated from their mothers and kept with peers. Observations were conducted when they were about three to five years old. The monkeys exhibited locomotive and repetitive stereotyped behavior such as turning, backward somersaulting, and bouncing. Most showed both turning and backward somersaulting. Observations indicated that social interactions with peers following maternal separation at the age of 3 to 5 mo. produce the locomotive and repetitive stereotyped behavior and that turning may change to backward somersaulting for older infants. Further work with controls for several factors is needed.