Responses of wild titi monkeys, Callicebus coimbrai (Primates: Platyrrhini: Pitheciidae), to the habituation process

Pedro Souza-Alves, JoãoF. Ferrari, Stephen

Adequate habituation of free-ranging subjects is essential for any field study, but is generally unsystematic. Here, attempts to habituate three titi monkey (Callicebus coimbrai Kobayashi & Langguth, 1999) groups are described, and factors determining the effectiveness of the process are discussed. The "relentless pursuit" approach was aided by playback recordings of vocalizations but only one group was habituated adequately. Average contact in 13 encounters with group 1 was just over one minute, whereas in 32 encounters with group 2, it averaged 3,5 minutes (maximum = 22 minutes). Group 3 was more tolerant of observers, and was considered fully habituated by the seventh encounter. The factors determining this disparity remain unclear, although vegetation density seems important. Whereas group 3 occupied an area of relatively undisturbed forest, with a sparse understory, the other groups occupied a habitat with dense undergrowth and an irregular canopy. The subjects' tolerance may have been affected by reduced visibility and less discreet behavior of the observers. On 10 occasions, the members of group 2 leapt to the ground and fled through the undergrowth. The results indicate the need for a careful evaluation of habitat characteristics prior to the selection of groups for habituation.

1. habituation
2. habitat
3. observation
4. Behavior