Tarsius tarsier
spectral tarsier

Tarsius spectrum is found on the islands of Sulawesi, Great Sangihe, and Peleng, in the Indonesian archipelago (Macdonald, 1987).

The habitat of T. spectrum is primary and secondary rain forest, although this species usually prefers to live in secondary growth forest. This is probably because of the presence of many saplings, creepers, and bamboos in secondary forest. Tarsius spectrum is usually found in dense patches of bushes, tall grasses, bamboos and small trees. (Macdonald, 1987)

Tarsius spectrum is one of the smallest of the primates. Its short body and round head are covered with a soft, velvety coat which is gray to gray-buff in color. Its tail is long, slender, and covered in scales like those which are found on the tails of rats and mice. It has a long and bushy tail tuft at the end.

Tarsius spectrum has a head-body length of 9.5 to 11 cm, and a tail length ranging from 20 to 26 cm. There is little difference in size between the males and females of the species. The head and body length together is only half as long as the entire hind limb (including the thigh, lower leg, and foot, all of which are greatly elongated and about equal in length to one another). The tibia and fibula of this animal are fused together in the lower portion to act as a shock absorber when the animal leaps from tree to tree.

The fingers and toes of T. spectrum are very long and slender in order to allow the animal to cling to trees and branches. Its second and third toes have a special toilet claw which it uses for grooming. The other toes and fingers all have nails.

The most characteristic feature is of T. spectrum is its enormous round eyes. In fact, the eye orbit of this animal is larger than both its brain case and its stomach. Each eye has a postorbital plate behind it, which protects the eyeballs from the powerful temporal muscles to their sides. The ears are very large and mobile. The large teeth are needle sharp.

(Macdonald, 1987; Kavanagh, 1983; Schultz, 1969; http://www.snowcrest.net/goehring/a2/primates/tarsier.htm)

Each tarsier pair is essentially monogamous.

Breeding of Tarsius spectrum occurs throughout the year. Thus births occur throughout the year. The gestation period is approximately 6 months. Females give birth to only one offspring at a time.

(Hill, 1955; Schultz, 1969; Macdonald, 1987)

Although further details about reproduction are not available for this species, other tarsier species are better studied. The estrus cycle of Tarsius syrichta lasts from 18 to 27 days. Tarsius syrichta undergoes a 1 to 3 day estrus period. Young are fairly well-developed at brith, weighing approximately 20 to 31 g. Young are able to leap by about 1 month of age. The period of nursing is short, lasting about 45 days. At this age, the young are able to capture prey and may be weaned at any time thereafter. It is likely that T. spectrum resembles other members of the genus with regard to these characteristics.

The young are born in a fairly advanced condition (precocial). The newborn is already well furred, has open eyes and it is able to scramble around the branches, athough it usually travels by clinging to the fur on the abdomen of its mother with both hands and feet. Sometimes the mother carries the newborn in her teeth so as to leave her hands and feet free for leaping and clinging to trees. The young tarsier cannot leap until it is a month old. Instead, it moves around on the ground by shorts hops. At the age of 3 weeks, the baby begins to accept living food.

Although data are not available on the lifespan of this species, another member of the genus, T. syrichta, is reported to have lived 13.5 years in captivity. Tarsius spectrum is likely to have a similar maximum lifespan.

Tarsius spectrum is crepuscular (active in the twilight) and nocturnal. Tarsius spectrum spends its days asleep, wakes up at dusk, and then proceeds to groom itself by licking its own fur. After this routine grooming, it then goes off in search of prey, which it locates mainly through use of its sharp ears.

It is famous for its leaping abilities; it is able to cross gaps of up to 6 m (20 ft). It clings to thin tree trunks with its long fingers and toes, and presses its tail against the tree in order to prop itself up. It often times even sleeps in this vertical position.

Tarsius spectrum is unable to walk. When it does come down from the trees, it moves around by hopping along on its hindlegs in a bipedal position with its tail held vertically in the air.

Tarsius spectrum is the most primitive of the modern tarsiers. It has developed the least specialization to its nocturnal lifestyle and to its exclusively leaping movement between vertical trunks and branches. For example, Philippine tarsiers, T. syrichta, have adhesive discs on their toes which enable them to climb up smooth branches; these are lacking in T. spectrum.

Tarsius spectrum usually lives in pairs or in small family groups. Each group or pair has its own home range, although these home ranges sometimes overlap. It defends its territory if necessary, but it attempts to avoid conflicts by marking its territory with urine and a secretion from the skin gland on its chest, called the epigastric gland.

Pair members or groups may stay together, uttering social calls around the sleeping site in the middle of their home range. In these spacing calls, the male and female often perform a sort of duet. Most of the calls are very high pitched and contain elements which humans are unable to hear.

Tarsius spectrum is considered to be a rather gentle creature, capable of displaying and having affection for both members of its own species, and humans that it knows. Despite this fact, when a tarsier is frightened it can be very aggressive and will react by biting. This is especially true of the males of the species.

(Hill, 1955; Kavanagh, 1983; Macdonald, 1987)

Communication in this species involves many elements. Tactile communication between mothers and their young, as well as between mates, is certainly of importance. In addition, these animals use complex vocalizations to space themselves and maintain contact while foraging. Scent marking, with urine as well as glandular secretions, occurs. Although visual communication has not been documented, it is likely that these animals use various body postures and other visual signals in communication.

Tarsius spectrum is both insectivorous and carnivorous, although there is much variation in diet between individuals. Its diet can consist of ants, beetles, cockroaches, scorpions, lizards, bats, snakes, birds, small mammals and others. It drinks several times each night by lapping up water with its tongue. Tarsius spectrum often uses its long fingers as a cage to trap its insect prey. It catches its other prey by leaping at it, pinning it to the ground, and then killing it with a few bites. It then takes its prey up to a perch and eats it head first. Tarsius spectrum eats almost all parts of its prey, even feathers, beaks, and feet. (Macdonald, 1987; Kavanagh, 1983)

Because of its nocturnal and crepuscular habits, as well as its arboreal nature, owls are the most likley predators upon tarsiers.

These animals are likely important in controlling and structuring the populations of their prey. To the extent that they are preyed upon by other animals, they may have some impact upon predator populations as well.

One of the ways in which T. spectrum is important to biologists is that it has a crucial systematic position between other prosimians and monkeys, which makes tarsiers relevant to many of the problems of primate evolution. Because of their small size, gentle temperament, and ability to be tamed, many people attempt to make pets out of these animals. Problems arise because T. spectrum is a somewhat delicate creature, and requires live food. Usually, when kept as pets, these creatures die in a matter of days. There have actually been cases when a captured tarsier has become so traumatized that it killed itself by banging its head against the bars of its cage. Another reason keeping T. spectrum as a pet is not a good idea is that all tarsiers which have been examined have been found to have some forms of intestinal worms, such as hookworms and tapeworms, to which humans are susceptible.

(Macdonald, 1987)

As mentioned above, these animals carry parasites which can affect humans who try to keep them as pets. However, in their natural environment, they do not pose a significant threat to humans.

Tarsius spectrum is very abundant on the island of Sulawesi and is only endangered where the forest is being logged. Logging is responsible for killing tens of thousands of these creatures each year. In both Indonesia and Malaysia, there are laws designed to protect the tarsiers. (Macdonald, 1987)

In the past, tarsiers were used as a totem animal of the head-hunting Iban people of Borneo. This was due to the fact that the Ibans believed the animal's head was loose because of its ability to swivel 180 degrees to the right or left. Some natives would not refer to tarsiers by name because they feared that in doing so they would become haunted.

Fossils of the genus Tarsius have been found in Asia, Europe and America, although the group is now restricted to the Southeast Asian islands. They have lived in this area for over 40 million years.

(Macdonald, 1987)