Cooperative breeding systems are rare in the animal kingdom. They are exhibited by several species of birds, canids, and primates. A cooperative breeding system is unique from other breeding systems for the high level of alloparental care of the offspring by unrelated and related members of a group. Adults tend to delay dispersal to stay in their natal group to tend to the offspring of the breeding female. In the primate order, callitrichids are the only family of primates to exhibit a cooperative breeding system. Callitrichids are New World monkeys that have several unique characteristics, one which includes habitual twin births. Because there is high reproductive output by the single breeding female in a callitrichid group (two twin births a year), alloparental care is necessary for the twin offspring to survive to adulthood.

There have been many studies on the interactions between adults and the offspring in callitrichid groups, especially with affiliative behaviors such as allogrooming, maintaining proximity, and food sharing. However, the literature of the interactions between adult pairs in such groups are scant compared to adult-infant interactions. These several studies suggest social bonds between adult males and females are maintained through several affiliative mechanisms. I studied the maintenance of social bonds in adult pairs of cotton-top tamarins (Saguinus oedipus) in two zoos from June through August, 2006. Data on proximity, allogrooming, scent-marking, and food sharing behaviors were observed and recorded during the study as measures of the strength and maintenance of the social bonds between these adult pairs. The results show adult males in the adult pairs spent more time in close proximity with the adult females. The adult females scent marked more often than the adult males and did anogenital scent marking more than any other type of scent marking. Food sharing was a very rare occurrence where there was only one transfer of a food item from an adult male to an adult female. These findings from my study are consistent with what is found in previous callitrichid studies. However, allogrooming frequencies were different and inconsistent. The maintenance of social bonds in adult pairs of callitrichids is of interest in order to better understand cooperative breeding systems and how they function. This study provides a little more information on an area marked by a lack of studies devoted to this issue, which should be addressed through further study of behaviors seen in wild and captive populations.