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.