Physical description
The Pygmy Tarsier has a head-body length of 95 to 105 mm (about 4 inches), and weighs less than 57 grams (2 ounces). T. pumilus has very distinct morphological features, a body length which is smaller than other tarsier species, and a small body weight. It also has smaller ears than the rest of the genus, and its fur is tan or buff with predominant grey or brownish red coloring. The tail is heavily haired and ranges from 135 to 275 mm. The most noticeable feature of T. pumilus are its large eyes, about 16 mm in diameter. The Pygmy Tarsier also has nails on all five digits of each hand and on two digits of each foot. The claw-like nails aid in its grasping strength and are also used as an aid in its need for vertical support for feeding and movement.
Behavior
T. pumilus is found in stable bonded pairs, remaining together for up to 15 months. This stable pair bond is usually monogamous. The species has two breeding seasons, one at the beginning of the rainy season and the other at the end, separated by about 6 months. Gestation lasts 178 days on average, and births occur in May and from November to December. Infants are quite precocial, and develop quickly, similar to other juveniles in the genus. The offspring begin capturing their own prey around 42 days of age, and travel in groups after only 23 days. Young females remain with parents until adulthood, while young males leave the natal group as juveniles.
The Pygmy Tarsier is nocturnal or crepuscular, and is mainly arboreal. It spends most of the daylight hours sleeping on vertical branches in the canopy. T. pumilus is not a nest builder. Unlike other tarsier species, it does not use scent glands to mark territorial boundaries. Also, tactile communication and interaction is important with the Pygmy Tarsier, as in other tarsier species.
Diet
Tarsiers, in general, are insectivorous, and tarsiers are the only primates that are completely carnivorous. They eat arthropods, and there are anecdotal stories of T. pumilus capturing birds and snakes. As insectivores, they also play an integral role in their habitat in structuring the insect community and in the local food webs.