The Tarsier: A Strange and Endangered Primate of 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 animal's thin and elongated fingers and toes have large adhesive pads at their tips, making them look swollen. Tarsiers also have very long and powerful hind legs which are folded up when they aren’t being used. The animal's strange appearance 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—in the trees. They also sleep, mate and have their babies in the trees.
There is still a lot that is unknown about the natural life of a tarsier. Unfortunately, the populations of many types of tarsiers are in trouble. These animals need our help in order to survive.
Discovering the Tarsier
Types of Tarsiers
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 and subspecies. Many of these are endangered.
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 the types of tarsier from each other, though. The different kinds of tarsiers differ in features such as body size, the size of their eyes, their limb proportions, and their vocalizations. Another difference is the length of the tail tuft. A tarsier has a long tail which is hairless except for a tuft at the end.
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 is slightly bigger that the mouse lemur. 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.
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. The eyes of a tarsier can’t rotate, but the animal can turn its head almost 180 degrees in each direction. This features gives it a 360 degree view of the world and enables it to leap backwards.
Hands and Feet
The third finger is the largest of the digits in the hand. Most of the tarsier's digits have nails, but there are grooming claws on the second and third toes.
The name “tarsier” comes from the elongated tarsal bones in the animal’s feet. The big tarsal bones, the long hind legs, which are about twice as long as the animal's head and body, and the strong leg muscles make the tarsier a very good leaper.
The Eyes of a Tarsier
Tarsiers need their large eyes to help them see in the dark. Unlike the eyes of many other nocturnal animals, tarsier eyes lack a tapetum lucidum. The tapetum 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 of an animal with a tapetum, some of the light is absorbed. Some passes through the retina and hits the tapetum, however. 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.
The Philippine tarsier is said to have the largest eyes in proportion to its body size of any animal on the planet. The giant squid has the largest eyes in the world with respect to the physical size of the eye.
Tarsiers live in forests and treed areas of various types. They also live in areas with shrubs or bamboo plants. The animals are sometimes seen in grasslands but seem to use these areas only to travel from one habitat to another.
Tarsiers are usually found 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 independent movement of a tarsier's ears helps the animal to locate its prey. Its long hind legs provide a powerful thrust for its leaps. Tarsiers 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. 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.
An Expressive Primate
Most tarsiers seem to be social animals, but the degree of closeness and social interaction varies according to the species. Although tarsiers generally live in groups, the space between the group members during their various activities varies. The most social animals snuggle together, groom each other and play with each other. They may also share food.
The animals 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 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.
Tarsiers are territorial. They patrol their territory and advertise it with scent marking and vocalizations. The animals 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.
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. It shows aggression by crouching with an open mouth and lunging or by standing on two legs.
Reproduction and Lifespan
Mating behavior varies. Some tarsier species appear to be monogamous, with one male mating with one female. In other species, a male seems to mate with several females.
Gestation lasts five or six months. Only one baby is born. The babies are large at birth and weigh 20% to 33% of the adult's weight. Their eyes are open and their fur has developed. The youngsters are able to climb almost immediately after they are born. The mother carries her baby around in her mouth, however.
The young tarsier develops rapidly. Weaning takes place when the baby is about eighty days old. In at least some types of tarsier, other females help the mother to take care of the baby.
The lifespan of the different tarsier species is uncertain. In the wild, some individuals are believed to live for twenty years or more. The lifespan is generally much shorter in captivity.
The Tarsius Project: Tarsier Research and Conservation
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. Here farmers may kill the animals, unaware that the tarsiers aren't eating the crops but are instead eating the insect pests feeding on the crops. Political unrest has also destroyed tarsier habitats. In addition, the animals 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.
A Visit to the Philippine Tarsier Foundation
In general, tarsiers don't do well in captivity and have a high death rate. They sometimes repeatedly bang their heads against the bars of their enclosure, injuring themselves. Some people are keeping captive tarsiers in large and natural habitats, however. These people have been more successful in breeding the animals and in keeping them relatively happy.
There are some organizations—such as the Philippines Tarsier Foundation—that are trying to keep captive tarsiers physically and mentally healthy and to breed them. They also aim to 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 of this fascinating little animal.
© 2011 Linda Crampton