THE EFFECT OF PARTURITION ON THE INTERACTIONS WITHIN PAIRS OF COMMON MARMOSETS (CALLITHRIX-JACCHUS)

The relationship within common marmoset (Callithrix jacchus) pairs is based on pair-bond formation. This pair-bond is important for the succ essful rearing of the young and for the enhancement of reproductive su ccess. Female marmosets bear twins which are carried mainly by males s tarting on the first day after the birth of the infants. Little is kno wn, however, about the patterns of sociosexual interaction between cal litrichid pairs and how these interactions change after the arrival of offspring. To evaluate the effect of parturition on these interaction s, three heterosexual pairs of common marmosets were observed for four weeks before and four weeks after the birth of infants. The animals w ere kept in individual outdoor cages of the Nucleo de Primatologia, un der environmental conditions. The time spent in proximity was mainly a ttributable to the initiative of females before parturition and the in itiative of males after the offspring arrived. Males were groomed more before than after the birth of infants. In contrast, the amount of gr ooming received by females was the same in the two situations. These o bservations suggest that the relationship within pairs of common marmo sets is slightly modified by the birth of infants and indicates that m ales and females could be using different strategies to enhance their reproductive success.