A field study of the social behavior of Goeldi's monkeys (Callimico goeldii) in North Bolivia. I. Group composition, breeding cycle, and infant development

Abstract

A group of Callimico was artificially baited in North Bolivia. After all of group members were identified completely, systematic observation of social behaviors was conducted. During the investigation, two infants were observed in the course of development for their first three months of life. The chronology of their growth is made. Females Callimico are polyoestrous. They can be pregnant twice a year. There are two fertile females in the group. After 10 days of giving birth to an infant, copulation occurs. The gestation period ranges 150-180 days. The infants solely cling to their own mother for first 10 days of life, and then begin to receive the non-mothers' care till they get independence at the age of 7 weeks. Infant-and food-transferring behaviors are performed by every group member. The frequencies of these behaviors show the highest level when the infants are 4-5 weeks old. Efects of the delivery of the infants and their development on group organization are discussed in terms of the function of species-specific care-taking behaviors.