AN INVESTIGATION INTO THE SOCIOENDOCRINOLOGY OF INFANT CARE AND POSTPARTUM FERTILITY IN GOELDI MONKEY (CALLIMICO-GOELDII)

We investigated the existence of interaction between the major behavio ral and endocrine events that occur in breeding pairs of Callimico dur ing the postpartum period: the reduction in maternal care, the onset o f maternal aggression, the onset of paternal care, and the resumption of female fertility. While the frequency of nursing remained constant throughout the 6-week observation period decreasing amount of time spe nt nursing generally preceded the onset of paternal carriage. Decreasi ng nursing duration was not associated with the occurrence of postpart um ovulation. Some mothers frequently acted aggressively toward the in fant during the period of first mother-to-father transfer of the infan t while other mothers did not. There is no correlation between the int erval to the first transfer and the period to postpartum ovulation. We validated urinary cortisol as a measure of stress and defined the dur ation of its poststress elevation as approximately 3 hr. There is no c onsistent relationship between female behavior and endocrine state, or male cortisol values and the onset of infant carrying by fathers. Dur ing the peritransfer phase, no significant change in cortisol concentr ation occurred, while the pre-, peri-, and postovulatory phases appear ed to be reflected in urinary cortisol output by some males. Based on these results, we propose an explanatory model for the causal dynamics of infant care in pairs of Callimico. The model stresses the importan ce of a high reproductive rate to male and female reproductive strateg ies.