Social System
http://www.csew.com/cottontop/SSP/Enghome.htm
The social group of the tamarin is made up of about 3 to 13 individuals, which includes infants (Smuts et.al, 1987). There have been reports of temporary splitting of groups of the cotton-top tamarin and several "transient non-reproductive groups" (Savage 1990). The transient groups tend to switch territories frequently, do not have a specific territory, and their home range overlaps frequently with established groups (Savage, 1990). Transient groups are non-reproductive because they are usually subordinate and have a hard time finding a mate. Therefore, it is common for them to change territories frequently. The switching of territories by sub-adults and adults within the cotton-top tamarin social group ensures that there is variation within the level of relatedness among the tamarins (Solomon et.al, 1997).
Researchers have not come to a definite conclusion about the social grouping of the cotton-top tamarin. However, certain patterns in social organization within wild and captive tamarins have led them to believe that tamarins live in cohesive family groups with a dominance hierarchy. Within the groups, it has been found that there is usually one reproductively active male and female (Massicot, 2005). In the wild, the cotton-top tamarin family group is usually made up of a breeding pair, their offspring, and one or two tamarins that are not in the family (Kirkwood and Stathatos, 1992). The members of the family group that are not related emigrate into the group and become integrated. The non-kin members are usually non-reproductive, subordinate individuals and they help with caring for the young (Savage, 1990). Caring for the young helps the sub-ordinate members by giving them experience, a place to live, and the protection of the family group.
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The cotton-top tamarin faces high predation pressure. Their predators are: reptiles, mammals, and various kinds of "predatory birds" (Miller, 2002). They are at a disadvantage to large primates because their small size increases their predation. The foraging time of tamarins are decreased significantly because they spend much of their time hiding from predators. Therefore, by living in social groups they have “more eyes and ears for predator protection” and can decrease the energetic cost of performing anti-predatory behaviors (Miller, 2002). The previously mentioned statement is known as the “shared-vigilance model”. It states that as the number of vigilant watchers increases, individuals are able to expend more time foraging and in other activities (Miller, 2002). The tamarin relies on early detection of predators and performs several predator-avoidance behaviors when foraging. For example, they sometimes hide within the trees and bushes, “play-dead”, or remain immobile when they sense a predator (Miller, 2002). Likewise, the cotton-top tamarins have a specific adult member that acts as a vigilant for predators when the group is sleeping (Savage, 1990).
