The Tarsier - A Strange and Endangered Primate in Southeast Asia

Tarsiers are strange primates with huge eyes that look too big for their face. Each eye is as large as the tarsier’s brain. The eyes can’t move, so a tarsier has to turn its head to look at things. Its fingers are thin and elongated, and they have large adhesive pads at their ends, making the animal look as though its finger tips are swollen. Tarsiers also have very long and powerful hind legs which are folded up when they aren’t being used, large ears that can be moved independently of each other and a long tail which is hairless except for a tuft at the end. The strange appearance of the tarsier often reminds people of Yoda, the Jedi master in the Star Wars movies.

In the wild, tarsiers live only on the islands of southeast Asia. They are generally nocturnal, although they may be active at dawn and dusk as well. They make their home in trees or sometimes in shrubs. Here they climb and leap with ease. They catch most of their food - insects and other small animals - sleep, mate and have their babies in the trees.

According to the latest classification scheme there are three different groups of tarsiers: the western tarsier (genus Cephalopachus), the eastern tarsiers (genus Tarsius) and the Philippine tarsier (genus Carlito). Each genus contains different species or subspecies. Many of these are endangered, while the population status of the others is unknown. The species and subspecies differ in features such as body size, the size of their eyes, their limb proportions, the length of their tail tufts and their vocalizations. A tarsier's soft fur is grey or brown, and may have buff or reddish patches. Fur color isn’t a reliable way to distinguish all the types of tarsier from each other, though.

Size

Tarsiers are small animals. Although they are sometimes said to be the world’s smallest primate, that honor actually goes to the Madame Berthe’s mouse lemur of Madagascar. This mouse lemur has an average weight of 1.1 ounces and a head plus body length of 3.6 inches. The pygmy tarsier is also a tiny primate but doesn’t quite match the mouse lemur’s statistics. It weighs about 2 ounces and has a head plus body length of about 3.8 inches. The bigger tarsiers may reach around 5.2 inches in length (not counting the tail) and about 5.4 ounces in weight.

Vision

The tarsier has the largest eyes relative to its body size of any mammal. In some types of tarsier the eyes are not only large but also bulging. A tarsier's brain has a very large visual cortex, the area that analyzes the information received from the eyes, in proportion to the rest of the brain, and has other specialized eye and brain features in its visual system. The eyes can’t rotate, but a tarsier can turn its head almost 180 degrees in each direction, giving it about a 360 degree view of the world and enabling it to leap backwards.

Tarsiers need their extra large eyes to help them see in the dark because, unlike the eyes of many other nocturnal animals, tarsier eyes lack a tapetum lucidum. This is a light-reflecting layer behind the retina at the back of the eyeballs. The retina is the part of the eye that detects light. When light strikes the retina, some is absorbed, but some passes through the retina and hits the tapetum. It’s then reflected back to the retina which absorbs some of the reflected light. The tapetum therefore gives the retina two chances to absorb light rays, helping the animal see better in the dark. Tarsiers need their large eyes to see at night since they don’t have a tapetum to help their vision.

Hands and Feet

The third finger is the largest of the digits on the hand. Most of the digits have nails, but there are grooming claws on the second and third toes. Adhesive pads are present on both the fingers and the toes.

The name “tarsier” comes from the elongated tarsal bones in the animal’s feet. These big bones, the tarsier's long hind legs, which are about twice as long as its head and body, and its strong leg muscles make the animal a very good leaper.

Tarsiers live in forests and treed areas of various types, and also in areas with shrubs or bamboo plants. They are sometimes seen in grasslands, but seem to use these areas just to travel from one habitat to another. Tarsiers are usually found only a few meters above the ground, although they will occasionally go higher or leave the trees and come to the ground. They cling to trunks and branches and move through the trees mainly by climbing and leaping. They also walk on all four legs and have been observed hopping on their hind legs.

The tarsier’s long hind legs provide a powerful thrust for its leaps and the independent movement of the ears helps the animals to locate their prey. They often leap on to the prey to catch it. The Philippine tarsier has even been observed catching insects in the air, using its hands as a cage.

The tarsier is the only primate that is entirely carnivorous - it eats only animals, and no plants. The diet consists mainly of insects, such as crickets, beetles and termites, but tarsiers will also eat small frogs, lizards, crabs, snakes, birds and even small bats and fish. They eat live prey and keep their eyes closed as they chew.

Most tarsiers seem to be social animals, but the degree of closeness and social interaction varies according to the type of tarsier. Although tarsiers generally live in groups, the space between the group members varies. The most social animals snuggle together, groom each other and play with each other, and they may also share food.

Tarsiers sleep in tangled vegetation or in tree cavities. They sleep alone or with one or more companions, depending on the type of tarsier. The Philippine tarsier is a solitary animal, however.

Tarsiers are territorial. They patrol their territory, and advertise it with scent marking and vocalizations. Tarsiers have scent glands on their lips and abdomens. Urine, feces and fluids from their reproductive tracts also contain smelly chemicals that serve to mark a territory or communicate with other tarsiers in the same group. Tarsiers may group together to chase potential invaders away.

Tarsiers are vocal animals and produce a wide variety of sounds. Some male-female pairs sing sunrise duets together before they go to sleep. Researchers have found that the spectral tarsier makes 15 different sounds in addition to the morning duet. These sounds include a variety of alarm calls, contact sounds and food calls.

During the day a tarsier frequently furls its ears (rolls or folds them up) and then unfurls them. A tarsier indicates fear by keeping its ears furled and aggression by crouching with an open mouth and lunging or by standing on two legs.

Gestation lasts about five or six months. Only one baby is born. The babies are large at birth - 20% to 33% of the adult's weight - and their eyes are open. Their fur has also developed and the youngsters are able to climb almost immediately after they are born. The mother carries her baby around in her mouth. A tarsier youngster develops rapidly. Weaning takes place when the baby is about 80 days old. At least in some types of tarsier, other females help the mother to take care of the baby.

Predators of tarsiers include owls, tree snakes, monitor lizards, civets and feral cats. Some humans hunt tarsiers for food. Habitat destruction for agriculture and human settlement is the biggest threat to tarsier survival, as it is for so many endangered animals. Tarsiers sometimes travel through agricultural areas and farmers may kill them, unaware that the tarsiers are carnivores and aren't eating the crops but are actually eating the insect pests on the crops. Political unrest has also destroyed tarsier habitats, and tarsiers are captured for the pet trade.

The IUCN (International Union for Conservation of Nature) maintains a "red list" which identifies the population status of different animals. Many tarsier types are classified in the Near Threatened, Vulnerable and Endangered categories of the red list. The Siau Island Tarsier of Indonesia is listed as critically endangered.

The oldest tarsier on record lived to be sixteen years old. In general, though, tarsiers don't do very well in captivity and the death rate is high. They don't reproduce well and sometimes repeatedly bang their hands against the bars of their enclosure or other hard objects, injuring themselves, sometimes fatally.

There are some organizations - such as the Philippines Tarsier Foundation - that are trying to keep captive tarsiers physically and mentally healthy and breed them, as well as educate the public, research tarsier behavior and conserve the habitat of wild tarsiers.

All tarsiers used to be classified in the genus Tarsius, but the Philippine tarsier is now placed in the genus Carlito. The genus is named after Carlito Pizarras, who is associated with the Philippines Tarsier Foundation, in honor of his efforts to protect tarsiers and his successful breeding of the animals in captivity. He's often known by the name of Nong Lito and is sometimes called "The Tarsier Man" because of his conservation efforts. Conservation organizations and people committed to tarsier protection are badly needed in order to save the wild populations.