Bioacoustics of Tarsius lariang

Descriptive notes. Head-body average 12-1 cm (males, n = 12) and 11-8 cm (females, n = 22), tail average 24 cm (males, n = 12) and 24-7 cm (females, n = 23); weight average 118 g (males, n = 12) and 102 g (females, n = 23). The Lariang Tarsier is a distinctive form, differentiated from tarsiers of mainland Sulawesi by its unique features of pelage, body proportions, skull, and vocalizations. It has very dark gray-buff pelage, lacking brown tones on the thighs. Its tail is very dark (often blackish) with a thick, black terminal tuft. It has well-marked thick, black paranasal stripes and well-marked black eye-rims. Hairs around the mouth are whitish, and there is a small bare spot at the base of each ear. The third digit of the hand is absolutely longer than in any other Sulawesi mainland tarsier. The Lariang Tarsier has a unique duet; distinguished from other members of the genus in that entire individual notes of the female song are upwardly frequency modulated. The Lariang Tarsier is the largest of the mainland Sulawesi tarsiers, and, compared to island forms, smaller only than the Great Sangihe Tarsier (7. sangirensis ) of Sangir Island.

Movements, Home range and Social organization. Lariang Tarsiers live in small groups and show social and territorial behavior, including sleeping-site associations and morning duet calls, similar to other tarsiers on Sulawesi. Field observations found that ten of eleven social groups were composed of one adult male, one adult female, and up to two putative offspring. They shared sleeping sites and foraged together. The eleventh group in the study possibly had more than nine individuals. The social structure of the groups was not established, but they foraged in subgroups of varying composition and size and came together at dawn at the same sleeping site. Multiple individuals performed duet songs. Both males and females disperse to other groups.