A phased process to reintroduce a hand-reared infant Tonkean macaque to her natal group

What is it about?

After giving birth, a female in a captive group of seven Tonkean macaques did not take care of her newborn. We removed the infant and hand-reared her with the aim of reintroducing her to the group after weaning. However, adding an immature individual to a multimale-multifemale group is risky, as the newcomer may no longer be recognised as a member of the group and therefore be attacked. The infant was brought to the front of the group enclosure daily for a period of two months, allowing them to see, hear, smell and even touch each other through the enclosure fence. We then started a phased reintroduction process that lasted a year. Because the mother was the individual most attracted to the infant, the process began by allowing the two individuals to freely interact in a special enclosure. In the next stages, we introduced the infant to the other group members one after the other in a special enclosure, starting with the females. The females were able to act as protectors against potential aggression from the males. Two years later, the introduced individual was fully integrated within her group and appeared to behave like the other group members. This report shows that it is possible to reintroduce an infant to a macaque group containing several adult females and males. The long and phased process contributed to the success of the reintroduction, in particular by allowing the infant to successively establish social relationships with each of the group members.

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