Social Behavior of a Reproducing Pair of the Philippine Tarsier (Tarsius syrichta) in Captivity.

Social interactions of the nocturnal primates are not well studied. One of the species for which social behavior is scarcely known is the Philippine tarsier (Tarsius [= Carlito] syrichta). We observed a reproducing pair of captive individuals over two mating seasons for two consecutive years. The tarsiers spent approximately 4% of their activity budget on social interactions; ca. 20% of time in 0-1 m proximity to each other; and shared sleeping sites for half of the study time. The majority of the animals' social interactions were peaceful: affiliative and sexual (83%), and the smallest component of the behavior was agonistic (17%). We witnessed two copulation events (one per estrus day), each lasting ca. 5 min, and both occurring just after waking. We revealed temporal - nightly and hourly - fluctuations in the frequency of social interactions, in the distances the individuals spent from each other and in the number of vocalizations. The results present the first assessment of the social behavior of the Philippine tarsier, much needed to improve the captive breeding management for this highly sensitive species threatened with extinction.

Activity Patterns of Captive Philippine Tarsiers (Tarsius syrichta): Differences Related to Sex and Social Context.

Among tarsiers, nocturnal, obligatory faunivorous primates inhabiting islands of South-East Asia, the Philippine tarsier (Tarsius [= Carlito] syrichta) is one of the least studied. To date, activity patterns of this threatened species have not been the subject of any investigation. In the present study, we provide the first quantitative data on how captive male and female T. syrichta apportion their time for various activities in two social contexts: solitary and paired. We found that the sexes do not differ in activity budgets during the non-mating season, both spending most of their time scanning, resting, foraging and travelling. Comparison of activity budgets of the sexes between the mating and non-mating seasons revealed that although both tarsiers noticeably increased travelling time at the expense of time spent resting, the male changed his behaviour to a much greater extent than the female. We also report on fluctuations in the tarsiers' activities throughout a night and compare time budgets of T. syrichta with available data on the western and eastern species of tarsiers. The results extend the current knowledge of tarsier behaviour and may also assist in practical considerations for keeping this highly sensitive, difficult-to-breed species in captivity.