Tarsius bancanus
western tarsier

Tarsius bancanus is found on the islands of Sumatra and Borneo, and on some small islands adjacent to these large ones.

This species is found in dense strands of bamboo, jungles, coastal forests, dense vegation, primary and secondary rain forests, shrubs, plantations and even in some settlements and gardens.

Western tarsiers, T. bancanus, are best known for their enormous eyes, which are approximately 16 mm in diameter. Their bodies range from 85 to 165 mm, and weights range between 80 and 160 g. The extremely long tail, which can reach 135 to 275 mm, is naked except for tufts of hair at the end. The fingers are extremely long and have pads on the tips. All of a tarsiers' toes have flattened nails except for the second and third toes; these end with claw-like nails. The membranous ears are slender and almost bare. Hair has a silky, velvety texture, and the pelage coloration ranges from grayish brown to dark brown, to ocher, beige and sand-colored.

Other species in this genus have been reported to live as long as 13.5 years in captivity, and T. bancanus is probably similar. It is likely that the lifespan in the wild is somewhat shorter.

Tarsiers have many physical characteristics that aide in hunting. Huge eyes help this nocturnal animal see in the dark. Sensitive ears, superficially similar to those of bats, are in constant motion. Tarsiers use their heightened senses of hearing and smell to catch prey. They can turn their heads in almost a 360 degree angle, enabling them to see both predators and prey. Upon locating potential prey, tarsiers adjust their position and pounce on the unsuspecting animal. Their ears are so sensitive that they can detect prey by hearing alone, and they often close their eyes before and during the catching of their prey. (This beahvior probably helps to protect their huge eyes from injury during pey capture). Once prey are captured in the elongated hands of the tarsier, it is bitten several times on the head and carried to a perch where it is eaten head first.

Hunting occurs at night, after the tarsier has spent the entire day sleeping in dense vegetation or in hollow trees. A tarsier's favorite position to sleep is upright against a tree trunk or branch, using the tail for support. Tarsiers sleep in different places in their territory each day, and arise from slumber at sundown or during early evening, when insects are most active.

Their offspring, which they sometimes carry in their mouths, are usually left in deep vegetation while the mother hunts. Tarsiers keep in constant contact with their offspring through high-pitched calls, yells and noises. Tarsiers' eyes, which can weigh more than their brains, are essential in their capture of their prey. Tarsiers have excellent night vision. Also, their ears are very sensitive, and they can hear long distances. Upon detecting a predator, a tarsier closes its eyes until the predator is almost directly on top of it. At this point, it opens its huge eyes and bares its sharp teeth in an effort to scare off the predator.

Tarsiers are known for their extraordinary leaping abilities. On average they can leap 2m in distance and up to 1.5 m in height. During the course of a leap, they twist their bodies in the air as they extend their fingers to grasp a branch. Tarsiers' long tails are used for support and balance during the leap and afterward. Their long fingers give them the ability to grasp almost any surface.

Tarsiers' leaping abilities are correlated with their unique hind leg structure. Their forelegs are shorter than the exceedingly long hind limbs, and in fact, their name, tarsier, means elongated ankle area. Tarsiers leap with their tail head upwards.

Tarsiers can also walk on all fours. When doing this, they prefer to keep their tails pointed downward.

Tarsiers are territorial; males mark their area, which is approximately 1 hectare, with urine on branches or with a special secretion from their epigastic gland. Tarsiers are extremely vocal and make loud shrieks with their partners. In fact, they call in harmony, with each partner making its own distinct sounds.

They use their third and fourth toes to groom themselves by scratching with their toe claws and licking their fur, avoiding their faces. Faces are cleaned by rubbing on branches. Tarsiers prefer to groom themselves except during mating season, when they groom each other.

Home Range

The territory of most tarsiers is between 1 and 2 hectares.

As mentioned above, tarsiers use a variety of means of communication. They mark their territories with scents from urine and glandular secretions. They use vocalizations to maintain contact and positioning. Grooming and other physical communication is important between mates, as well as between mothers and their offspring. Visual signals, such as baring teeth, are used when they are threatened.

Tarsiers are mainly insectivorous, but they are known for their carnivorous habits, which include eating small animals like lizards, crustaceans, bats, and even scorpions and poisonous snakes. Tarsiers must have access to free water to drink.

Predation upon tarsiers has not been well documented. Because of their nocturnal and arboreal habits, these animals are most likely to fall prey to owls. However, diurnal raptors may prey upon sleeping tarsiers during the daylight hours. They also may be victims of small carnivores capable of climbing into the canopy where these tarsiers live.

As both predators and prey, these animals play an important part in local food webs.

Tarsiers are hosts to intestinal worms that can be harmful to humans. It is questionable, however, if humans would naturally contact these worms if the tarsiers were left in their natural habitat. Contact is more likely when people keep these animals as pets.

Tarsiers consume large quantities of potentially harmful insects. They are also used in the pet trade. In addition, scientific research on these animals is often conducted because of their unique taxonomic position.

Pesticides on plantations and destruction of their forest habitat are threatening the future of tarsiers. Because of the destruction of the rain forests, tarsiers are losing habitat daily. Also, because of the hunting of these unique animals, they are being killed and captured at an alarming rate. The only places where tarsiers are protected by law are Malaysia and Indonesia. Listed in CITES Appendix 2.

If the eyes of a human were the same in proportion to our bodies as those of the tarsier, our eyes would be as large as apples. The tibia and fibula of tarsiers (bones at the hind leg) are much modified, enabling their incredible acrobatic skills.

Tarsiers can eat 10% of their body weight in one day.

Because of their appeal to humans, tarsiers are often captured to make pets. However, because they require live food, tarsiers die within days of capture.