There is evidence of long term pair bonding. Males are the primary caregiver of infants. Care includes carrying, guarding, playing with and sharing food with infants. This demands a significant amount of energy, as the males carry infants up to four months of age and often lag behind the rest of the group. Mothers nurse their young every 2 to 3 hours.
Infants are large in comparison to their parents' body mass and grow quickly.
Infant size and growth might explain the evolutionary adaptation of monogamy and male parental care, since infants demand more care than a single mother can provide. Aotus trivirgatus are usually found in family groups where older siblings live with their parents well past infancy and help the mating pair to raise their younger offspring. It has been suggested that this too is a result of the high energy demands of infants. Also, there are limited opportunities for juveniles and subadults to encounter single owl monkeys of the opposite sex with whom to break off from their natal group and form a new pair. Playing behavior in A. trivirgatus has been observed primarily between infants, juveniles, subadults and fathers.