Functional context of scent-marking in Callithrix penicillata.

Most mammals use olfactory signals for communicating identity, reproductive status and group-related dynamics. Callitrichids produce secretions as olfactory signals, the functional context of which is poorly known, especially in the wild. We analysed the functional significance of scent-marking in a free-ranging group of Callithrix penicillata in central Brazil. We recorded all occurrences of scent-marking according to context and conducted 10-min focal observations of adults and 'scan sampling' of the focal tree. We recorded the sex of scent-marking individuals and the location of occurrence within the home range, and found that there was no variation in rate of marking relative to either variable. However, females marked more along areas of contact with other groups in the home range and less in the core (non-contact) areas. Scent-marking in intergroup encounters, even when in agonistic contexts, was not associated with territorial disputes between groups. This suggests distinct functions for scent-marking for intra- versus intergroup communication. We also found a positive correlation between rate of scent-marking and height in the resource tree and between exudativory and air humidity.