Rearing condition may alter neonatal development of captive Bolivian squirrel monkeys (Saimiri boliviensis boliviensis)

Abstract

Nursery rearing has well-known consequences for primate species. Relative to some other primate species, research has indicated a reduced impact of nursery rearing on squirrel monkeys, particularly in terms of rates, severity, and persistence of abnormal behavior. We administered the Primate Neonatal Neurobehavioral Assessment to 29 dam-reared and 13 nursery-reared squirrel monkeys (Saimiri boliviensis boliviensis) at 2 and 6 weeks of age. Mixed-model ANOVAs comparing composite scores and individual assessment items across age, rearing status, and sex revealed a number of developmental differences. Dam-reared infants scored higher on all four composite measures compared to nursery-reared infants (p < .05) indicating that nursery-reared animals had slower motor development, were less active and attentive, and were more passive than their dam-reared counterparts. Consistent with infant rhesus macaques, nursery-reared squirrel monkeys showed an increased sensitivity to tactile stimulation (p < .05). Altogether, these results suggest a disruption of species-typical development when squirrel monkey infants are reared in a nursery setting, with activity, orientation, and state control areas most affected, though experimental research is needed to determine if this is a causal relationship. Contrary to previous behavioral research, there are likely developmental differences between dam-reared infant squirrel monkeys and those reared in a nursery setting.

Neonatal activity and state control differences among three squirrel monkey subspecies (Saimiri sciureus sciureus, S. boliviensis boliviensis, and S. boliviensis peruviensis)

“…If S. s. sciureus dams are more restrictive than dams as a result of this instability, it could explain the subspecies differences we observed in PNNA scores. Similarities between maternal restrictions of social interaction with peers and social restrictions in nursery settings may also explain why S. s. sciureus neurobehavior is similar to that of nursery-reared macaques and squirrel monkeys (Mulholland et al, ;Schneider & Suomi, 1992;Schneider, 1987;Schneider, 1992). This research is the first to show how documented differences in the Saimiri social organization can be seen in the neonatal neurobehavioral organization.…”

Maternal deprivation affects goat kids’ social behavior before and after weaning

“…Maternal deprivation increased a goat kid's ( Capra hircus ) behavioral reactivity to stressful situations and decreased its neophobia toward social and nonsocial stimuli (Lyons et al., 1988; Toinon et al., 2021). The mere absence of the mother and other adults in the social environment heightened the sensitivity to tactile stimulation in squirrel monkeys, Saimiri boliviensis boliviensis , and rhesus monkeys, Macaca mulatta (Mulholland et al., 2020), and increased the amount of self‐directed behavior performed by young rhesus monkeys, interpreted as a substitute for mother‐directed behavior (Champoux et al., 1991). Infant rhesus monkeys raised without their mothers also showed stronger affiliation with other infants, but played less frequently with peers than infants reared with their mothers, and tended to be more often excessively impulsive compared with mother‐reared infants (Suomi, 2009).…”