Tarsiers are agile acrobats, capable of impressive leaps of up to five or six metres (4) (7). The spectral tarsier is most active at night, the huge eyes giving good night vision, despite lacking the reflective layer, or ‘tapetum’, typical of most other nocturnal primates (2). In addition, the eyes are forward-facing, allowing the tarsier to accurately judge distances (2), and the head is able to rotate nearly 360°, giving an extremely wide field of vision (4) (5). Unusually for a primate, tarsiers feed exclusively on live prey, mainly taking insects, but also occasionally small vertebrates such as lizards (1) (2) (4) (5) (8). Prey may be taken in the trees or from the ground (7).
The spectral tarsier lives in small family groups consisting of a male, one or two breeding females, and young (2) (5) (7) (9). The group scent-marks and defends a small territory of around one hectare (2) (4) (5) (7) (10), and shares a sleeping site during the day (4) (7) (11). Group members also regularly interact during the night (11) (12) and come together again at the sleeping site at dawn. The group often perform a vocal chorus, and the male and female may also perform a duet, in which each has a distinct part (2) (4) (7). Breeding occurs twice a year, from April to May and November to December (2) (4) (7), the female giving birth to a single young, after a gestation period of around 190 days (2). Remarkably, the newborn is up to a third of the female’s weight, a larger proportion than any other mammal (2) (13). Well developed at birth, the young spectral tarsier is able to climb at just a day old and hunt alone by 26 days (2) (4) (5) (7). For the first few weeks, the infant may be carried in the female’s mouth or ‘parked’ on a branch while the group hunts (2) (5) (7) (14), with group members regularly returning to ‘babysit’, groom, feed or play with it (7) (13) (14).