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Tarsius bancanuswestern tarsier

By Paul McKeighan

Geographic Range

Tarsius bancanus is found in the Melay archipelago, on the islands of Sumatra and Borneo, as well as on several smaller islands. It can also be found on southern Sumatra, but its range is thought to be restricted in the north by teh Musi River. ("Tarsiidae (Tarsiers)", 2003; Niemitz, 1984; Shekelle and Yustian, 2010)

Habitat

Preferred habitat of Tarsius bancanus is primary and secondary forest, although it can also be found in mangroves and forest edges. It is a vertical clinger and leaper, and generally does not venture into more open areas unless both prey and small-diameter trees to cling to are present. It can also be found along the forest edge and in fruit plantations. Although it is generally described as a lowland species, residing below 100 m in elevation, sightings above 1200 m have been documented. ("Tarsiidae (Tarsiers)", 2003; Niemitz, 1984)

  • Range elevation
    0 to 1200 m
    0.00 to 3937.01 ft

Physical Description

The most striking feature of tarsiers is their large eyes, which are larger than those of any other mammal, with respect to body size. Tarsius bancanus is small. Males are 12 cm in length on average and range in mass from 122 to 134 g. This species is sexually dimorphic, as females are on average 10 grams lighter than males. Its fur is grey and/or brown and does not help distinguish it from the other tarsiers species. It has a very long tail, nearly twice as long as its head and body. The tale is scaly in appearance, with the exception of a tuft of hair near the distal end. In general, tarsiers have extraordinarily long hind legs (the longest legs of any mammal in proportion to body length), which contributes to their primary mode of locomotion as vertical clingers and leapers. The forelimbs are rather shorter. All four limbs end in long, thin digits, and the front digits have disc-like pads. (Crompton and Andau, 1986a; Niemitz, 1984)

  • Sexual Dimorphism
  • male larger
  • Range mass
    122 to 134 g
    4.30 to 4.72 oz
  • Average length
    129 mm
    5.08 in

Reproduction

It was previously assumed that tarsiers, including Tarsius bancanus, had a high incidence of monogamy. However, recent evidence suggests that the mating system is highly dependent on prey availability, and that T.bancanus is most likely polygynous. Females signal their readiness to mate both chemically and visually. When in estrus, females exhibit labial swelling and scent-rubbing near territorial borders shared with males. Once males identify estrous females, the often perform "courtship calls." (Niemitz, 1984; Roberts, 1994; Simons, 1986)

Tarsius bancanus mates non-seasonally, and gestation lasts 178 days on average. It has 1 offspring per mating period, which can be up to 25% of the mother body weight. This species generally has slightly more than one birth per year, with an average inter-birth timespan of 258 days. Tarsius bancanus are moderately precocial at birth, as they are able to climb but not leap. Most young are weaned by 80 days after parturition. (Roberts, 1994; Simons, 1986)

  • Breeding interval
    On average every 258 days.
  • Breeding season
    Mating is nonseasonal.
  • Average number of offspring
    1
  • Average number of offspring
    1
    AnAge
  • Average gestation period
    178 days
  • Average gestation period
    178 days
    AnAge
  • Average weaning age
    80 days
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    920 days
    AnAge

After parturition, male western tarsiers are aggressively chased away by the mother until the baby reaches maturity. Captive males have been known to kill their young. Young do not develop locomotor independence for about four weeks; until then, they are "parked" while mothers forage for prey. Unlike many other primates, mother's rarely carry young, which may be due to the large-size of newborns. Other than providing milk and protection from the father, mothers offer limited care to their offspring. (Niemitz, 1984; Roberts, 1994)

  • Parental Investment
  • precocial
  • female parental care
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • provisioning
      • female
    • protecting
      • female
  • extended period of juvenile learning

Lifespan/Longevity

Little is known about tarsiers' lifespan, but is estimated for T. bancanus at 12 years. The relative lack of predators and limited fecundity of tarsiers points to a relatively long lifespan. ("Tarsiidae (Tarsiers)", 2003; Roberts, 1994)

Behavior

Tarsius bancanus is a vertical clinger and leaper. It uses its tail and hind limbs to support itself on vertical surfaces, normally saplings. They strongly prefer trees with trunks smaller than 4 cm in diameter, with the majority being about 2 cm. Its upper vertebrae are modified to allow the head to rotate 180 degrees. Leaping makes up the majority of its locomotion, and it spends only 5% of its time on the ground. Tarsius bancanus is able to leap horizontal distances up to 45 times its body length, or about 5.8 meters. It is completely carnivorous and often captures prey by leaping. It prefers prey that are on tree trunks rather than on the ground, where it is less mobile. Regardless of where its prey is caught, T. bancanus returns to a tree to perch to consume its prey. ("Tarsiidae (Tarsiers)", 2003; Crompton and Andau, 1986a; Crompton and Andau, 1986b; Niemitz, 1984; Roberts and Kohn, 1993)

Western tarsiers are nocturnal and sometimes crepuscular and are most active in the hours immediately after dusk. The tarsier's gigantic eyes allow it to hunt at night. Differing from other tarsiers, the western tarsier is quite solitary, coming in contact with other members of its species only for mating, establishing territory, or raising young. Western tarsiers often return to the same general area to sleep, if not to the same perch. They tend to hunt within 1 m of the ground, and sleeping perches are usually found on a vertical or near-vertical structure over 4 m high. ("Tarsiidae (Tarsiers)", 2003; Crompton and Andau, 1986a; Crompton and Andau, 1986b; Niemitz, 1984; Roberts and Kohn, 1993)

  • Range territory size
    .045 to .1125 km^2
  • Average territory size
    .085 km^2

Home Range

The home range of western tarsiers ranges from 0.045 km^2 to 0.113 km^2, with an average of 0.085 km^2, and male territories tend to be slightly larger than those of females. Radio-telemetry data of western tarsiers showed that males traveled farther during the night than females. ("Tarsiidae (Tarsiers)", 2003; Crompton and Andau, 1986a; Crompton and Andau, 1986b)

Communication and Perception

Tarsius bancanus relies mostly on sight for foraging and depends upon sound and smell for intraspecific communication. Of all tarsier species, T. bancanus is the least communicative. Where touching and grooming are common in most other species, it has only been documented between mothers with young and mating pairs. Territory is marked with urine, scent from glands in the ano-genital region, and secretions from the epigastric gland. Tarsius bancanus communicates with potential mates via squeaks and whistles, and physical contact prior to copulation is usually initiated by grasping the tail. (Niemitz, 1984)

Food Habits

Western Tarsiers are exclusively carnivorous, most commonly feeding on insects. They consume almost any kind of insect, as well as some small vertebrates, including birds, mammals and reptiles. The prey upon anything that moves, including animals as large as themselves. They have even been sighted preying upon spotted-winged fruit bats tangled in mist nets. ("Tarsiidae (Tarsiers)", 2003; Hodgkison and Kunz, 2006; Jablonski, 1994; Niemitz, 1984; Roberts and Kohn, 1993; Rosenberger, 2010)

  • Animal Foods
  • birds
  • mammals
  • reptiles
  • insects
  • terrestrial non-insect arthropods

Predation

There is little information available on the major predators of western tarsiers. Their brown/grey pelage allows them a certain degree of camouflage and helps decrease risk of predation. More importantly, their arboreal nature keeps them out of reach of most predators, however, snakes and arboreal mammals (e.g., slow lorises) are likely their primary predators. They are likely most vulnerable when they are chewing, as they are unable to hear approaching predators. ("Tarsiidae (Tarsiers)", 2003; Niemitz, 1984)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Western tarsier are primarily insectivorous, and may help control insect pest populations. In addition, they are host to various species of intestinal worm (Moniliformes tarsii and Moniliformes echinosorexi), tapeworms and roundworms. Little else is known of parasites specific to this species. ("Tarsiidae (Tarsiers)", 2003; Deveaux, et al., 1988; Niemitz, 1984; Roberts, 1994)

Commensal/Parasitic Species
  • intestinal worm, (Moniliformes tarsii)
  • intestinal worm, (Moniliformes echinosorexi)
  • tapeworms, (Cestoda)
  • roundworms, (Nematoda)

Economic Importance for Humans: Positive

Although Tarsius bancanus may help control insect pest populations throughout its range, there are no known positive effects of this species on humans

Economic Importance for Humans: Negative

There are no known adverse effects of Tarsius bancanus on humans.

Conservation Status

Tarsius bancanus is classified as "vulnerable" on the IUCN's Red List of Threatened Species, primarily due to a 30% habitat loss over the last 20 years. Despite this, more information is needed to determine overall population trends. Major threats include habitat loss due to forest conversion to palm plantations and collection of individuals for the illegal pet trade. Despite the fact that this species is 100% carnivorous, it is sometimes considered an agricultural pest and appears to be especially vulnerable to contamination from agricultural pesticides. This species is listed under Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) and is protected by law in Indonesia and Malaysia. ("Tarsiidae (Tarsiers)", 2003; Shekelle and Yustian, 2010)

Contributors

Paul McKeighan (author), University of Michigan-Ann Arbor, Phil Myers (editor), University of Michigan-Ann Arbor, John Berini (editor), Animal Diversity Web Staff.

Glossary

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

crepuscular

active at dawn and dusk

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

insectivore

An animal that eats mainly insects or spiders.

island endemic

animals that live only on an island or set of islands.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

polygynous

having more than one female as a mate at one time

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

saltatorial

specialized for leaping or bounding locomotion; jumps or hops.

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

year-round breeding

breeding takes place throughout the year

young precocial

young are relatively well-developed when born

References

2003. Tarsiidae (Tarsiers). Pp. 91-100 in Grzimek's animal life encyclopedia, Vol. 14, Second Edition. Detroit: Gale.

Crompton, R., P. Andau. 1986. Locomotion and habitat utilization in free-ranging Tarsius bancanus : A preliminary report.. Primates, 27: 337-355.

Crompton, R., P. Andau. 1986. Ranging, activity rhythms, and sociality in free-ranging Tarsius bancanus : A preliminary report.. International Journal of Primatology, 8: 43-72.

Deveaux, T., G. Schmidt, M. Krishnasamy. 1988. Two new species of Moniliformis (Acanthocephala: Moniliformidae) from Malaysia. The Journal of Parasitology, 74/2: 322-325.

Hodgkison, R., T. Kunz. 2006. Balionycteris maculata. Mammalian Species, 793: 1-3.

Jablonski, N. 1994. Feeding Behavior, Mastication, and Tooth Wear in the Western Tarsier (Tarsius bancanus).. International Journal of Primatology, 15: 29-60.

Niemitz, C. 1984. Biology of tarsiers. Stuttgart: Gustav Fischer Verlag.

Roberts, M. 1994. Growth, development, and parental care in the western tarsier (Tarsius bancanus) in captivity: Evidence for a "slow" life-history and nonmonogamous mating system. International Journal of Primatology, 15: 1-28.

Roberts, M., F. Kohn. 1993. Habitat use, foraging behavior, and activity patterns in reproducing western tarsiers, Tarsius bancanus, in captivity: A management synthesis. Zoo Biology, 12: 217-232.

Roberts, M. 1988. "Management and Husbandry of the Western Tarsier (Tarsius bancanus) at the National Zoological Park" (On-line). Laboratory Primate Newsletter - Volume 27, Number 2. Accessed May 25, 2011 at http://www.brown.edu/Research/Primate/lpn27-2.html?keepThis=true&TB_iframe=true.

Rosenberger, A. 2010. The Skull of Tarsius: Functional Morphology, Eyeballs, and the Nonpursuit Predatory Lifestyle. International Journal of Primatology, 31: 1032-1054.

Shekelle, M., I. Yustian. 2010. "Tarsius bancanus" (On-line). The IUCN Red List of Threatened Species. Accessed May 25, 2011 at http://www.iucnredlist.org/apps/redlist/details/21488/0.

Simons, E. 1986. Reproductive Cycles in Tarsius bancanus. American Journal of Primatology, 11: 207-215.

Sussman, R. 1999. Primate ecology and social structure. Needham Heights, MA: Pearson Custom Pub..

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