BEHAVIOR AND PROGESTERONE LEVELS IN CALLITHRIX-JACCHUS FEMALES

In callitrichids, and especially in the Callithrix and Saguinus genera , reproductive suppression maintains the breeding exclusivity of domin ant females. It has been suggested that dominance may be inferred from agonistic behavior of females. The purpose of this study was to asses s the adequacy of behaviors as indicators of hormonal status in Callit hrix jacchus females. Two pairs of twin females were observed for affi liative, agonistic and sexual behaviors for 20 weeks, in four stages o f increasingly potential competition for one male. During the same per iod, blood samples were taken regularly for progesterone determination by ELISA. The two pairs differed markedly as to behaviors and hormona l status: pair 1 showed a well established behavioral dominance and on ly one ovulating female from the beginning of the observation period; pair 2 showed competition for dominance until the last stage of observ ation, when one of the females started ovulating. Correlations between behaviors and progesterone levels showed differences between subordin ate and dominant females mostly in pair 2. Although limited in number of animals studied, these results suggest that there is a relationship between behavior and hormones in female marmosets, but this relations hip may be useful in the identification of the physiological status of females only in groups where the dominance is not well established.