Analysis of infant carrying in large, well-established family groups of captive marmosets (Callithrix jacchus).

To assess the pattern of infant carrying across time and family members, we counted which animals in 13 well-established family groups of captive-bred marmosets (Callithrix jacchus) carried neonates during the first 8 weeks of life. The neonates were carried almost continuously for the first 3 weeks and then spent progressively more time independently. The mother did most of the carrying for the first 2 weeks, her contribution rising from day 1 to day 3 and declining thereafter. The contribution of the father was high on day 1, declined during the first week, and then rose to a peak in the fourth week. The contribution of the siblings rose sharply during the first week and declined thereafter. There was no overall difference in amount of infant carrying by each parent. The contribution of each sibling was small although in these large families the total contribution by siblings was large. These data may differ from previous observations because the breeding pairs were very well established, the families were large, and all except the youngest animals were very experienced in rearing and carrying. These data emphasise the group-dynamic nature of infant carrying in a primate species.