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Differentially reared juvenile rhesus (Macaca mulatta) macaques' response to novel stimuli in their home environments: A measure of behavioral flexibility
Abstract
Thirteen differentially-reared juvenile rhesus macaques (Macaca mulatta) were subjects in a twenty-one week long study investigating macaques' behavioral responses to novel stimuli. Both animate (an unfamiliar conspecific) and inanimate objects (ball, board and hanging acrylic cylinder) were presented to the monkeys while in their home cages. All subjects were female; seven were nursery-raised/peer-reared and six family-grouped (unimale/multifemale) raised. Scan and focal-sampling techniques were used to collect data on forty-two behaviors. The fifteen most frequently occurring behaviors (each accounting for one percent of total behavioral frequencies) were statistically tested. The focal sample data was analyzed on both an overall and across treatment level using a Student's t test and Chi square analysis. The intergroup differences occurred both during baseline and manipulation periods. The family-grouped subjects approached novel stimuli earlier and interacted with the objects more often than did the peer-grouped monkeys. The intergroup differences were statistically significant (p $<$.05), both on an individual and group level. Among the similarities observed between the differentially-reared juveniles were an increase in behavioral frequencies over time, a preference for the edges rather than central portions of the cage, and comparable frequencies of aggression when the animate stimulus (unfamiliar monkey) was present. Scan samples were made on the focal juvenile-aged subjects, as well as all other members of the seven groups (two peer groups and five family groups). The animals' utilization of space and behavioral frequencies were recorded pre- and post-focal sampling observations. The peer-reared monkeys lagged behind the family-reared individuals in their occupation of cage areas near the novel stimuli by eighteen weeks. Also, the family-reared juveniles tended to approach novel stimuli in manners comparable to the adults in their groups. The peer-reared juveniles' approaches were similar in frequency and nature to the family-grouped yearling and infants' displays. A preliminary follow-up study of the animals' reproductive activity indicates intergroup differences. During their first two years of parenthood the peer-reared females became pregnant earlier and more often than family-reared females. Over the two year period the peer-reared females had fourteen pregnancies versus the family-reared females' nine. But, the peer-reared had two stillbirths, three neonatal deaths and one infant rejection. One out of nine pregnancies resulted in a stillbirth among the family-reared females. The intergroup differences and similarities, both as juveniles and as adults, are discussed as possible measures of behavioral flexibility in this species. The theoretical and practical implications of restricting macaques' social rearing conditions are presented.
Subject Area
Behaviorial sciences|Physical anthropology
Recommended Citation
Watson, Lyna M, "Differentially reared juvenile rhesus (Macaca mulatta) macaques' response to novel stimuli in their home environments: A measure of behavioral flexibility" (1995). Doctoral Dissertations Available from Proquest. AAI9541164.
https://scholarworks.umass.edu/dissertations/AAI9541164