the bark of appropriate trees and vines with its specialized dentition to elicit the production of gum. When the sap puddles up in the hole, they lap it up with its tongue. They also lie in wait for insects, especially butterflies, which are attracted to the sap holes. They supplement their diet with nectar and fruit. A group's home range is , and feeding is usually concentrated on one or two trees at a time. When those become depleted, a group moves to a new home range. Brown-mantled tamarins are generally sympatric with pygmy marmosets and often raid pygmy marmosets' gum holes. Pygmy marmosets have adapted insect-like claws, known as tegulae, to engage in a high degree of claw-clinging behaviors associated with plant exudate exploitation. Claw-clinging is primarily used during feeding, but also during plant exudate foraging. Behaviour A pygmy marmoset group, ranging from two to nine members, contains one or two adult males and one or two adult females, including a single breeding female and her offspring. Interbirth interval ranges from 149–746 days. In contrast to other callitrichines, there is no relationship between the number of adult males and the number of infants and offspring. However, there is a significant positive relationship between the number of juveniles and the number of adult and sub-adult group members. Young marmosets typically remain in the group for two consecutive birth cycles. The pygmy marmoset uses special types of communication to give alerts and warning to its family members. These include chemical, vocal, and visual types of communication. It is believed to serve to promote group cohesion and avoidance of other family groups. Social systems Infant pygmy marmosets, along with their parents, twin, and other siblings, form cooperative care groups. Babbling, or vocalizing, by the infant marmoset is a key part of its relationships with its family members and is a major part of its development. As the infant develops, the babbling gradually changes to resemble and eventually become adult vocalization. There are many similarities between the development of vocalization in infant pygmy marmosets and speech in infant humans. Vocalizing gives the infant advantages such as increased care and allows the entire family to coordinate their activities without seeing each other. Siblings also participate in infant care. Infant marmosets require the most attention, so having more family members participating in the care decreases the cost for any individual and also teaches parenting skills