Range and distribution
The Philippine Tarsier, as its name suggests, is endemic to the Philippine archipelago. Tarsius syrichta populations are generally found in the southeastern part of the archipelago. Established populations are present particularly on the islands of Bohol, Samar, Leyte and Mindanao.They have also been found on various isolated islands within its known range, such as Maripipi Island, Siargao Island, Basilan Island and Dinagat Island.
Ecology and life history
Habitat
The Philippine Tarsier's habitat is the second growth, secondary forest, and primary forest from sea level to 700 m. Its habitat also includes tropical rainforest with dense vegetation and trees that offer it protection like tall grasses, bushes and bamboo shoots.
Research findings also show that the Philippine Tarsier prefer dense, low-level vegetation in secondary forests, with perching sites averaging 2 meters above the ground.
Home range
Initial studies show that the Philippine Tarsier appears to have a home range of 1 to 2 hectares. Recent research shows that home ranges averaged 6.45 hectares for males and 2.45 hectares for females (MCP and Kernel 95%), allowing for a density of 16 male and 41 female tarsiers per 100 ha.
Research findings also show that while both male and female tarsiers are solitary animals, they cross each other's paths under the cover of nightfall as they hunt for prey. They travel up to one and a half kilometres across the forest and the optimal area is more than six hectares.
Ecosystem roles
Besides human hunters, feral cats banished from nearby communities are the species' main predators, though some large birds are known to prey on it as well. Because of its nocturnal and arboreal habits, the Philippine Tarsier is most likely to fall prey to owls, or to small carnivores which it can encounter in its canopy homes.
Feeding ecology
The Philippine Tarsier is carnivorous. Primarily insectivorous, its diet consists of live insects and it has also been observed to feed on spiders, small crustaceans, and small vertebrates such as small lizards and birds. Tarsius syrichta preys on live insects, particularly crickets and grasshoppers. Upon seizing its prey, the tarsier carries it to its mouth using both hands.
As predators, the Philippine Tarsier may help to structure insect communities. To the extent that it is preyed upon by other animals, it may impact predator populations.
Behavior
The Philippine Tarsier is a shy nocturnal animal that leads a mostly hidden life, asleep during the day and only active to look for food during the night. During the day, it sleeps in dark hollows close to the ground, near the trunks of trees and shrubs deep in the impenetrable bushes and forests. They only become active at night, and even then, with their much better sight and amazing ability to maneuver around trees, are very well able to avoid humans.
It is arboreal and is a vertical clinger and leaper, habitually clinging vertically to trees and are capable of leaping from branch to branch.
The Philippine Tarsier is solitary. However, it is found to have either monogamous or polygamous mating system.
Communication
The Philippine Tarsier uses varied means of communication. Although less vocal than many primate species, it uses calls which are often associated with territorial maintenance and male-female spacing. Its "loud call" is a loud piercing single note. When content, it emits a sound similar to a soft sweet bird-like twill. And when several tarsiers come together, they have a chirping, locust-like sound.
Its vocal communication is the distress call made by infants when they are separated from their mothers. It is also the call made by males to their mates during mating season. Its olfactory communication is the marking of a scent from the circumoral gland which the female uses to mark her mate with the gland located around the mouth. It is also the marking of a male's territory with the use of urine. Its tactile communication is the social grooming done when one tarsier grooms the other, removing dead skin and parasites, observed in females on adult males, as well as in females on their offspring.
Life history
Reproduction
The Philippine Tarsier's pregnancy or gestation period lasts about 6 months. The female's estrous cycle lasts 25–28 days. Mating season begins in April to May. The males deposit a mating plug in the female's vagina after intercourse. The female gives birth to one offspring per gestation. The infant is born with a lot of hair and born with its eyes open. The females carry their infants in their mouth. A new born can already cling to branches and in less than a month after birth, it can start leaping.
The Philippine Tarsier reproduces poorly in captivity. the world's smallest monkey
Importance to humans
There is no known negative impact of the Philippine Tarsier on humans, just as long as it is in its native environment. However, when kept as pets, there is a possibility that the species may spread worms and other parasites to their human owners.
Tarsiers used to be kept as pets or sold for trade, although their survival in captivity is erratic due to their need for live insects upon which to feed. Scientists are interested in these animals because of their unique taxonomic position, and study of tarsiers may aid human economies.
Conservation
In 1986, the Philippines Tarsier was assessed as Endangered by the IUCN Conservation Monitoring Centre 1986. It was still assessed as Endangered by the IUCN Conservation Monitoring Centre in 1988, as well as in 1990 (IUCN 1990). In 1996, it was assessed as Lower Risk/conservation dependent by Baillie and Groombridge (1996).
On September 13, 1991, the Department of Environment and Natural Resources (DENR), per DENR Administrative Order Number 48 or DAO 48, listed the Philippine Tarsier as an endangered species: species and subspecies of wildlife whose populations are in danger of extinction and whose survival is unlikely if the causal factors continue operating.
The Philippine Tarsier is listed in Appendix II of CITES, and the U.S. ESA classifies it as threatened.
In 2000, the IUCN, having continuously listed the Philippine Tarsier as endangered, further assessed the Tarsius syrichta in its red list category and criteria as Data Deficient (DD) which means that there is inadequate information to make a direct or indirect assessment of its risks of extinction based on its distribution and/or population status. Further, it basically means that it is not known how close the species is to extinction or if it is a lower risk.
Being classified as such, the sale and trade of the species is prohibited. In addition, research on the species, particularly those using invasive techniques, is controlled by the DENR Environment Management Bureau (DENR-EMB) and requires Environmental Compliance Certificate/Environmental Impact Statement or ECC/EIS.
Threats to the species
For the past 45 million years, tarsiers have inhabited rainforests around the world, but now they only exist on a few islands in the Philippines, Borneo and Indonesia. In Bohol, the Philippine Tarsier was a common sight in the southern part of the island until the 1960s. Since then, the number has dwindled to as few as an estimated 1000 still left in the wild. Once protected by the humid rainforests and mist-shrouded hills, these mysterious primates struggle to survive as their home is cleared for crop growing.
Due to the quickly growing human population, which causes more and more forests to be converted to farmland, housing areas and roads, the place where the Philippine Tarsier can live its secluded life is disappearing.
Along this line, the dwindling of Philippine forests has posed a grave and significant threat to the survival of the Philippine Tarsier because this results in the destruction of its natural forest habitat. Indiscriminate and illegal logging, cutting of trees for firewood, "kaingin" or slash and burn method of agriculture, urbanization patterns have encroached on the habitats of the tarsier, causing the tarsier to be threatened or endangered.
The unabated hunting of the species by humans for house pets or for trade has contributed to its decline as well. Hunting tarsiers to sell as pets was a thriving industry until recently. Because of its adorable and benign appearance, many have been lured to keep the Philippine Tarsier as pets. This demand fuels the capture and illegal trade of the animal further diminishing its remaining number. Moreover, the life span for wild tarsiers is 24 years, but often as little as 12 years in captivity. Aside from the issues of replicating a natural diet, climate, and exercise that may reduce a captive tarsier's lifespan, stress may be added by the fact that many human owners want to interact with and display their pets by day, interrupting their nocturnal lifestyle.
Paradoxically, indigenous superstition coupled with relatively thick rainforest, particularly in Sarangani province, have apparently preserved this endangered species. Indigenous tribes leave the Philippine Tarsiers in the wild because they fear that these animals could bring bad luck. One belief passed down from ancient times is that they are pets belonging to spirits dwelling in giant fig trees, known as belete trees. If someone harms a tarsier they need to apologize to the spirits of the forest, or it’s thought they will encounter sickness or hardship in life.
