Langur monkey mother loss: profile analysis with multivariate analysis of variance for separation subjects and controls.

We present an analysis of observational data on the behavior profiles for two groups of infant langur monkeys (Presbytis entellus): one that had experienced mother loss, and the other, a control group, that had not undergone mother loss. Observations were analyzed in three 2-week time periods: 2 preseparation, 2 separation, and 2 postseparation periods for both groups. The profile analysis application of the multivariate analysis of variance (MANOVA) was employed to test the hypothesis that the two groups had similar patterns of change across time. For each group a vector of 5 difference scores was computed; then MANOVA was used to test the similarity of the mean vectors of difference scores for the two groups. Profiles for the separation and control infants were significantly different for some behaviors, and changes between some time periods were also significant.

Langur monkey (Presbytis entellus) development. The first 3 months of life.

Observation for the first 3 months of life of 19 Indian langur monkey infants (Presbytis entellus) living in well-established colony social groups revealed complex and related patterns of social development. This is a period of rapidly increasing infant motor ability and increasing infant-initiated independence. Infant transfer, a behavior initiated by others towards the infant and a characteristic of the species, occurs most frequently in weeks 1 and 2, then steadily declines to low frequency in weeks 11 and 12. Infants are not punished or rejected, and to the extent the mother allows, the infant leaves her. She leaves her infant infrequently. The infant widens its radius of activity and increases the kinds and frequency of active interactions it has with others in the group. Patterns of behavior appear to develop in tandem during key periods of early life. Week 1 is the time of greatest dependence with 100% contact at first. During weeks 3 and 4, the infant efficiently expresses itself and can actively prevent transfers. Week 4 sees a constellation of major changes and a rising infant drive for independence. Play increases as do interactions with other immatures. Carrying decreases as the infant is able to follow. Some restraints are observed because of a new set of infant management problems presented to the mother. Throughout the first 3 months of life the mother is the focus of her infant's attention and activities--she is crucial to its survival. The 3-month-old infant is an active strategist with many options of action and choices of behavior and social partners.

An experimental study of mother loss in the Indian langur monkey (Presbytis entellus).

Langur monkeys normally have many important caregivers from birth. Mothers of 6- to 8-month-old infants were removed from the infants' social groups for 2 weeks, and the effects of the separations on infant behavior were assessed. All infants showed changes in behavior. Their reactions to loss ranged from minimal to severe--in 2 instances, death. All infants sought care during separation, and most infants showed strong preferences for certain females. A majority of infants adopted a major caregiver during the mother's absence. Adoptions were entirely infant-initiated, and most infants remained with their adopted caregivers when the mothers were returned. Factors influencing infant response to mother loss included previous quality of maternal care, availability of accepting caregivers, and peer competition.