TARSIERS: Tarsiidae

PHYSICAL CHARACTERISTICS

Tarsiers (TAR-see-urz) weigh 2.8 to 5.8 ounces (80 to 165 grams). Body length is 3 to 6 inches (8 to 15 centimeters), and tail length is 5 to 11 inches (13 to 28 centimeters). They range in color from sandy to grayish brown to reddish brown. The undersides may be yellowish beige, grayish, or bluish gray. Relative to their body size, tarsiers have the largest eyes of all mammals. Their goggle-like eyes cannot move within the sockets, but a flexible neck can rotate the head 180 degrees for a backward look.

The tarsier is named for its powerful, extended tarsals (TAR-sullz), or ankle bones. The tarsals, together with the merging at the ankles of the two lower-leg bones, the tibia and fibula, allow for remarkable leaps. Fingers and toes are enlarged at the tip, with adhesive pads for gripping vertical branches. The tail is nearly naked, except for a tuft of hair on the tip.

GEOGRAPHIC RANGE

Tarsiers are found in the Philippines, Indonesia, and Borneo.

HABITAT

Tarsiers live in a variety of habitats. They occupy mainly secondary forests with enough canopies that provide vertical branches for clinging, usually about 3 to 6 feet (0.9 to 1.8 meters) above the ground. Tarsiers also inhabit shrublands, bamboo thickets, mangroves, grasslands, and plantations. They also live in primary forests with their characteristic dense canopies and thinner lower vegetation.

DIET

Tarsiers are carnivores, feeding mainly on live animals, including cockroaches, beetles, moths, lizards, snakes, and roosting birds. They consume almost every part of their prey, including the feathers, beaks, and feet of birds.

BEHAVIOR AND REPRODUCTION

Tarsiers are arboreal, spending most of their time in trees. They forage alone at night, although some species may be active at dawn or dusk. When catching large insects, the tarsier closes its eyes, opening them only after putting the prey into its mouth. An insect's sharp body parts could do damage to the tarsier's big, exposed eyes. Tarsiers leap and cling to vertical branches. They communicate through high-pitched calls. When they get together to sleep during the day, tarsier pairs may perform duets, or a group may vocalize together as if in greeting.

Tarsiers have just one partner, mating year round or seasonally, depending on the species. After a pregnancy of about six months, the mother gives birth to a single, well-developed infant, about one quarter of her weight.

TARSIERS AND PEOPLE

Some people take tarsiers for pets. Some farmers mistakenly believe tarsiers eat crops and may kill the tarsiers. Actually, tarsiers help control some harmful insects, including grasshoppers, caterpillars, and moths.

FLYING ACROBAT

When preparing to leap from one tree branch to another, the tarsier rotates its head 180° toward the intended landing spot. Then pushing off from its perch using its powerful hind legs, it leaps backward. The body takes off like an acrobat's, twists around in mid-air, and aligns with the forward direction of the head. The tarsier then lands vertically, grasping the branch with its fingers and toes.

CONSERVATION STATUS

The World Conservation Union (IUCN) lists the Dian's tarsier as Lower Risk/Conservation Dependent, meaning its survival depends on conservation efforts. The Eastern tarsier is listed as Near Threatened, not currently threatened, but could become so, because of habitat loss and degradation due to human activities. The Philippine tarsier and three other species found in Indonesia are listed as Data Deficient, meaning the species may be well-studied but information about distribution is lacking.

PHILIPPINE TARSIER (Tarsius syrichta): SPECIES ACCOUNTS

Physical characteristics: The Philippine tarsier has soft gray fur, a body length of about 5 inches (13 centimeters), and a tail length that is twice as long (9 inches, or 23 centimeters). It weighs about 4 to 5 ounces (113 to 142 grams). The head is round and the snout is short. The enormous eyes that seem too big for the sockets are immobile. For side and back vision, the tarsier swivels its head, sometimes almost a full circle. The large, thinly textured ears move like giant antennas to track sounds made by crawling insects and other prey. Long fingers and toes have suction pads at the tips for gripping tree branches. All nails are flattened, except for the second and third toes, which are grooming claws used for removing dead skin and parasites from the fur. The nearly naked tail has a sandy coloration, with a tuft of hair at the tip. The inside part of the tail has ridges that help prop the tarsier against a tree trunk or branch, especially while it sleeps.

Geographic range: The Philippine tarsiers are found in the Philippine Islands.

Habitat: Philippine tarsiers inhabit small trees found under the canopy of less mature forests. They also occupy coastal rainforests. They live in tree hollows close to the ground and are also found in thick bushes and bamboo roots.

Diet: Philippine tarsiers prey on live crickets, beetles, termites, lizards, spiders, scorpions, frogs, and birds.

Behavior and reproduction: Philippine tarsiers mostly live in trees and shrubs, moving from branch to branch by leaping and clinging to vertical branches with their padded fingers and toes. The average jump covers about 5 feet (1.4 meters), with the greatest leaps recorded at 20 feet (6 meters). They also sleep while clinging to vertical branches, supported by their tail. Individuals sleep alone in dense vegetation close to the ground. On the forest floor, they hop, holding the long tail straight. They are nocturnal (active at night), preferring to forage alone. They are usually quiet, but call out to one another by squeaking in a high note, trilling, or chirping. Tarsiers scent mark tree branches, using urine and secretions from skin glands found within the lips, on the chest, and in genital areas.

A male Philippine tarsier may form a family group with one or two females and their offspring. Due to a long pregnancy (about six months), the newborn is well developed, having a full coat and open eyes. The mother carries the infant in her mouth while she forages in trees, resting the infant on branches while she feeds. The newborn is able to cling to branches and can jump after a month.

Philippine tarsiers and people: Some Filipinos believe it is bad luck to touch a tarsier. Others take tarsiers for pets. However, tarsiers do not make good pets. They dislike being handled and will inflict serious bites. They do not thrive in zoos, dying soon after captivity.

Conservation status: IUCN lists the Philippine tarsier as Data Deficient, a category that does not refer to a threatened species. This means that the species may be well studied, but information about its population status is lacking. Nevertheless, tarsiers have experienced habitat loss because of the clearing of land for agriculture and timber. ∎

WESTERN TARSIER (Tarsius bancanus:): SPECIES ACCOUNTS

Physical characteristics: The western tarsier is yellowish beige or sand-colored. Enormous, goggled eyes take up most of its face. The eyes cannot move within the sockets, so a flexible neck turns the head around almost 180° for a backward look. Large ears are in constant motion as they follow the sounds of possible prey. The fingers and toes are very long and have suction pads at the tips for gripping tree branches. Fingernails and toenails are flattened, except for those on the second and third toes. These two toes have grooming claws, used for cleaning the fur of dead skin and parasites and for scratching. The long, rod-like tail is bare with a small clump of hair at the end. Ridges on the inside part of the tail support the tarsier when it clings to tree trunks or branches.

Geographic range: Western tarsiers are found in Indonesia.

Habitat: Western tarsiers favor secondary forests, with their dense ground vegetation and small trees. They also inhabit primary forests, characterized by a full-ceiling canopy and trees of different heights. They are found in human settlements and plantations.

Diet: Western tarsiers eat primarily large insects, including beetles, cockroaches, praying mantis, cicadas, butterflies, and grasshoppers. They also feed on birds, bats, and snakes. They even eat poisonous snakes.

Behavior and reproduction: The western tarsier forages for food alone at night and at dawn and dusk, listening for sounds made by insects on the ground and catching them with its hands. It closes its eyes when attacking insects to protect its eyes. During the day, males and females sleep separately, either among vines and tangled vegetation or while clinging to vertical tree trunks or branches. Using urine and scent gland secretions, tarsiers scent mark tree branches to advertise territory ownership. They are rather quiet, although females vocalize when ready to mate.

Western tarsiers may be monogamous (muh-NAH-guh-mus), having just one partner, or polygynous (puh-LIH-juh-nus), with males having several partners. Births occur throughout the year, although more births occur between February and June at the end of the rainy season. Females give birth to a single infant that weighs about one quarter of its mother's weight. The well-developed infant is born with a full coat and open eyes. It can climb right away after birth.

Western tarsiers and people: The Ibans, the indigenous people of Sarawak, Borneo, who were once head-hunters, considered the western tarsier as an omen animal. They had seen the tarsier rotate its head full circle and thought the tarsier had a loose head. A headhunter who encountered a tarsier would turn around right away so as not to incur the spirits' spell on him and his people. Today, tarsiers are taken for pets but do not survive in captivity.

Conservation status: The IUCN lists the western tarsier as Data Deficient, a category that does not refer to a threatened species. This means that the species may be well-studied, but there is not enough information about its population status. ∎

FOR MORE INFORMATION

Books:

Kavanagh, Michael. A Complete Guide to Monkeys, Apes and Other Primates. New York: The Viking Press, 1983.

Napier, John R., and Prue H. Napier. The Natural History of the Primates. Cambridge, MA: The MIT Press, 1986.

Nowak, Ronald M. Walker's Primates of the World. Baltimore: The Johns Hopkins University Press, 1999.

Preston-Mafham, Rod, and Ken Preston-Mafham. Primates of the World. New York: Facts on File, Inc., 1992.

Web sites:

"Philippine Tarsier: Tarsius syrichta." The Philippine Tarsier Foundation, Inc. http://www.bohol.net/PTFI/tarsier.htm (accessed July 6, 2004).

Ramos, Serafin N. Jr. "The Tarsiers of Sarangani." Sarangani, Mindanao, Philippines Website. http://www.sarangani.gov.ph/news/tarsier/m04tarsier.html (accessed July 6, 2004).

"Tarsiers (Tarsiidae)." Singapore Zoological Garden Docents. http://www.szgdocent.org/pp/p-tarsir.htm (accessed July 6, 2004).