The family Callitrichidae contains two types of monkeys, marmosets and tamarins. Of these two, previously only the tamarin has been the subject of a long term study in the natural habitat. This is a two year field study in the caatinga scrub forest of northeastern Brazil of the social strategies of the common marmoset (Callithrix jacchus). This study provides an unparalleled opportunity to study a group of animals that exhibit polyandry, monogamy and polygyny in a single population. Previous studies of tamarins indicated that the polyandrous tendencies in this family are the result of the high costs of rearing the infants in this genus. This study will replicate previous data collection techniques in tamarins in order to test the validity of this model in marmosets. This research will contribute to our understanding of the development and proximate causes of mating systems, and provide a data base on the natural behavior of the common marmoset, a species frequently utilized in laboratory research.
