Animal Diversity Web

Ge­o­graphic Range

Spec­tral tar­siers, Tar­sius tar­sier, are en­demic to the In­done­sian is­lands of South­east Asia in­clud­ing Su­lawesi, Pulau Pe­leng, and Pulau Se­la­jar. The great­est den­si­ties of this species are found in the north­ern penin­sula of Su­lawesi Is­land. (Wright, et al., 2003)

• Biogeographic Regions
• oriental
  • native

• Other Geographic Terms
• island endemic

Habi­tat

Spec­tral tar­siers are found in pri­mary and sec­ondary rain­forests, though they pre­fer sec­ondary growth forests. This is likely due to the greater abun­dance of food items in sec­ondary growth forests. Their habi­tat ranges from the low­land ever­green rain­for­est near sea level to the lower mon­tane rain­for­est up to 1500 m. Spec­tral tar­siers have also been found in man­groves and scrub for­est. (Wright, et al., 2003)

• Habitat Regions
• tropical
• terrestrial

• Terrestrial Biomes
• rainforest
• scrub forest
• mountains

• Range elevation

  0 to 1500 m

  0.00 to 4921.26 ft

Phys­i­cal De­scrip­tion

Spec­tral tar­siers have a small, round body cov­ered in soft, vel­vety fur. Their pelage ranges from gray to buff-gray in color. They have long scaly tails with tufts of fur only pre­sent on the dis­tal third of the tail. Spec­tral tar­siers ex­hibit sex­ual di­mor­phism: fe­males weigh 102 to 114 g while males weight 118 to 130 g.

Mem­bers of the genus Tar­sius pos­sess long, slen­der hands, feet, and dig­its. Their hands are thought to be the longest of any liv­ing pri­mate rel­a­tive to body size. These ex­tremely elon­gated hands are de­signed for cling­ing and grip­ping de­spite the lack of op­pos­able thumbs. The third fin­ger of T. tar­sier is ex­tremely long and slen­der and is only 15% shorter than the humerus. This trait is not sym­met­ri­cally re­pro­duced from the an­te­rior to the pos­te­rior, as the fourth digit is the longest of the hindlimb dig­its. The sec­ond and third dig­its of the hindlimb are equipped with spe­cial­ized toi­let claws. Spec­tral tar­siers are thought to be the most prim­i­tive tar­siers, as they lack disks on the ends of their fin­gers.

Tar­siers are among the small­est known pri­mates. Their head-body length ranges from 9.5 to 14 cm and tail length ranges from 20 to 26 cm. Total length ranges from 29.5 to 40 cm. Spec­tral tar­siers have long legs that are spe­cial­ized for their salta­tory form of lo­co­mo­tion; they can jump more than 40 times the length of their body. The tibia and fibula are fused to­gether and act as a shock ab­sorber when the an­i­mal jumps from tree to tree. The hindlimbs of tar­siers are twice as long as their head-body length. The femur, the bones of the lower leg (the fused tibia and fibula), and the bones of the foot are each roughly equal in length. (Mac­Don­ald, 2006; MacK­in­non and MacK­in­non, 1980; McNab and Wright, 1987; Napier and Napier, 1985; Rosen­berger, 2010; Wright, et al., 2003)

Tar­siers have the biggest eyes of any mam­mal rel­a­tive to their body weight. In fact, their eyes are larger than their brain. In­ter­est­ingly, tar­siers lack a tape­tum lu­cidum, a highly re­flec­tive layer be­hind the retina that is char­ac­ter­is­tic of most noc­tur­nal mam­mals. In­stead tar­siers have ex­tremely large eyes and a well-de­vel­oped fovea to max­i­mize light-gath­er­ing ca­pac­ity and to allow the de­vel­op­ment of highly re­solved pin-sharp vi­sion. These adap­ta­tions have be­stowed tar­siers with the most acute night vi­sion of all pri­mates. The eyes of spec­tral tar­siers are im­mo­bile due to their large size, but this is com­pen­sated for by the abil­ity to ro­tate the head 180 de­grees.

The ears of spec­tral tar­siers are thin and mem­bra­nous and are able to move in­de­pen­dently. Tar­siers pos­sess sharp, het­erodont teeth and quadrate mo­lars. The den­tal for­mula of tar­siers is: I2/1, C1/1, P3/3, M3/3 = 34. Spec­tral tar­siers have a low basal meta­bolic rate and a low body tem­per­a­ture. They do not ex­hibit tor­por, yet brown adi­pose tis­sue can be found in adults within the in­ter­scapu­lar area; this is likely a re­tained pae­do­mor­phic trait. (Mac­Don­ald, 2006; MacK­in­non and MacK­in­non, 1980; McNab and Wright, 1987; Napier and Napier, 1985; Rosen­berger, 2010; Wright, et al., 2003)

• Other Physical Features
• endothermic
• bilateral symmetry

• Sexual Dimorphism
• male larger

• Range mass

  102 to 130 g

  3.59 to 4.58 oz

• Range length

  9.5 to 14 cm

  3.74 to 5.51 in

Re­pro­duc­tion

The ma­jor­ity of tar­siers are monog­a­mous; how­ever, spec­tral tar­siers may prac­tice fac­ul­ta­tive monogamy or polyg­yny. Monogamy ap­pears to be the preva­lent mat­ing sys­tem in this species due to lim­ited num­bers of high-qual­ity sleep­ing sites. Each in­di­vid­ual fe­male re­quires a high-qual­ity sleep­ing site for her­self and her young. Fig trees with large di­am­e­ters are pre­ferred but rare, which gen­er­ally leads males and fe­males to share sleep­ing sites and thus to form monog­a­mous pairs.

Polyg­y­nous groups occur 19% of the time. Monog­a­mous groups often con­sist of two or three fe­males with one re­pro­duc­ing fe­male and one ter­ri­to­r­ial male, while polyg­y­nous groups con­sist of six or more in­di­vid­u­als with mul­ti­ple re­pro­duc­ing fe­males and a sin­gle male. The pres­ence of large testes in T. tar­sier sug­gests that polyg­yny is fairly com­mon, as large testes have been re­lated to promis­cu­ous mat­ing sys­tems. (Gursky-Doyen, 2010; Mac­Don­ald, 2006)

• Mating System
• monogamous
• polygynous

Spec­tral tar­siers breed twice a year, and cop­u­la­tion oc­curs dur­ing ei­ther May or No­vem­ber. The ges­ta­tion pe­riod is ap­prox­i­mately 6 months, and births also usu­ally occur dur­ing May or No­vem­ber. Fe­males give birth to a sin­gle off­spring, which is born fully furred and with its eyes open. New­borns are pre­co­cial and are able to climb at just one day of age. Among mam­mals, tar­sier off­spring are the largest rel­a­tive to the mother's body mass. New­borns weigh on av­er­age 23.7 g, nearly 22% of the mother's body mass. A large pro­por­tion their weight is in­vested in the brain mass, eyes, and cra­nium.

Lac­ta­tion gen­er­ally lasts up to 80 days. Wean­ing oc­curs be­tween 4 and 10 weeks of age, and in­de­pen­dence oc­curs di­rectly after wean­ing as off­spring are ca­pa­ble of hunt­ing on their own. Spec­tral tar­siers reach sex­ual ma­tu­rity at 17 months of age. Fe­males pos­sess a bi­cor­nu­ate uterus and haemo­cho­r­ial pla­centa. (Gursky, 2002; Gursky-Doyen, 2010; Napier and Napier, 1985; Roberts, 1994)

• Key Reproductive Features
• iteroparous
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• viviparous

• Breeding interval

  Spectral tarsiers breed twice yearly.

• Breeding season

  Copulation May and November

• Average number of offspring

  1

• Average gestation period

  6 months

• Range weaning age

  21 to 80 days

• Range time to independence

  4 to 12 weeks

• Average age at sexual or reproductive maturity (female)

  17 months

• Average age at sexual or reproductive maturity (male)

  17 months

Young spec­tral tar­siers are pre­co­cial and re­ceive only ma­ter­nal care. Moth­ers pick up and carry their in­fants by mouth for the first 3 weeks and cache them trees while they for­age. Off­spring are left alone for an av­er­age of 27 min­utes at a time, and then they are moved to new lo­ca­tions. Moth­ers gen­er­ally re­main within 4 m of their young when for­ag­ing. Caching young in trees re­duces the en­er­getic cost of for­ag­ing, as car­ry­ing off­spring is costly and off­spring can weigh up to one third of the mother’s weight. Moth­ers sling off­spring older than 3 weeks of age under their bel­lies while leap­ing and mov­ing from tree to tree. (Gursky, 2010; Gursky-Doyen, 2010; Napier and Napier, 1985)

• 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
• post-independence association with parents

Lifes­pan/Longevity

One spec­tral tar­sier was 10 years and 9 months of age at the con­clu­sion of a mark and re-cap­ture study, and the only signs of aging in this in­di­vid­ual were gray/light hair on the face. There­fore, this prob­a­bly does not rep­re­sent the longest lifes­pan of spec­tral tar­siers in the wild.

A fe­male tar­sier greater than 5 years of age cur­rently re­sides at the Sin­ga­pore zoo. A closely re­lated species, Tar­sius ban­canus has a lifes­pan of 17 years and 7 months in cap­tiv­ity. It is likely that T. tar­sier has a sim­i­lar lifes­pan in cap­tiv­ity. (Shekelle and Ni­etsch, 2008)

• Average lifespan
  Status: wild

  10 years

Be­hav­ior

Spec­tral tar­siers are both cre­pus­cu­lar and noc­tur­nal and are very ac­tive through­out the night. At dusk, they travel for about 30 min­utes until they find a for­age site. Dur­ing this time, they fre­quently stop to groom them­selves by lick­ing and scratch­ing their fur with their toi­let claws. If a heavy rain oc­curs, tar­siers find a dry area and re­main in­ac­tive. They move through the trees and can leap more than 40 times the length of their body. As morn­ing ap­proaches, spec­tral tar­siers "sing" as they re­turn to their sleep­ing sites, ei­ther as a duet with their mate or in a fam­ily cho­rus. These songs sig­nal to neigh­bor­ing groups that a ter­ri­tory is oc­cu­pied. Spec­tral tar­siers are ex­tremely ter­ri­to­r­ial and en­gage in dis­putes with neigh­bor­ing groups that ven­ture into their bound­aries. They mark their ter­ri­to­ries with urine and glan­du­lar se­cre­tions.

Spec­tral tar­siers usu­ally live in pairs or small fam­ily groups. They are highly so­cial an­i­mals. When two adult group mem­bers are in phys­i­cal con­tact, they spend all of their time rest­ing and so­cial­iz­ing. When less than 10 m apart, they for­age and, when they are 50 to 100 m apart, they spend most of their time trav­el­ing. Spec­tral tar­siers also en­gage in play be­hav­ior, snug­gling, al­logroom­ing, and food shar­ing. Com­pe­ti­tion for food re­sults in in­creased time for­ag­ing. In­di­vid­u­als ap­pear to ben­e­fit from group liv­ing, par­tic­u­larly when pre­da­tion pres­sure is high, when fe­males are sex­u­ally re­cep­tive, and when there is high like­li­hood of en­coun­ter­ing a po­ten­tially in­fan­ti­ci­dal male. (Gron, 2010; Gursky, 2002; Gursky-Doyen, 2011; MacK­in­non and MacK­in­non, 1980)

• Key Behaviors
• arboreal
• scansorial
• saltatorial
• nocturnal
• crepuscular
• motile
• territorial
• social

• Average territory size

  male 0.03 km^2, female 0.02 km^2

Home Range

The av­er­age home range of spec­tral tar­siers is 3 ha for males and 2 ha for fe­males. They have high site fi­delity, re­main­ing at the same sleep­ing site for mul­ti­ple years, usu­ally with a mate. Fe­males often es­tab­lish a ter­ri­tory ad­ja­cent to their parental ter­ri­tory, while males dis­perse twice as far as fe­males. Spec­tral tar­siers scent-mark their ter­ri­to­ries with urine and se­cre­tions from their epi­gas­tric glands. (Gursky, 2010)

Com­mu­ni­ca­tion and Per­cep­tion

Species-spe­cific vo­cal­iza­tions of spec­tral tar­siers in­clude trills and twit­ters, alarm calls, duet songs, and fam­ily cho­ruses. Twit­ters and trills are used to con­verse or to make their lo­ca­tion known to other group mem­bers while for­ag­ing. Alarms calls serve as a warn­ing sys­tem to oth­ers when a preda­tor is spot­ted and also en­cour­age preda­tor mob­bing. Duet songs and fam­ily cho­ruses con­vey ter­ri­to­ri­al­ity and func­tion as a mate guard­ing mech­a­nism. As morn­ing ap­proaches, the fe­male of the duet pair ini­ti­ates a song once she has re­turned to the fam­ily’s sleep­ing site. The male and fe­male sing very dif­fer­ent but equally high-pitched songs, which can be heard up to 100 m away. Species-spe­cific vocal acoustics are used in con­junc­tion with mor­pho­genet­ics to as­sess clas­si­fi­ca­tion of tar­siers.

Spec­tral tar­siers use their urine as well as se­cre­tions from the epi­gas­tric gland, ano-gen­i­tal gland, and cir­cum-oral gland to mark the bound­aries of their ter­ri­tory. Males scent mark twice as fre­quently as fe­males.

Phys­i­cal con­tact ap­pears to con­tribute to tar­sier so­cial­ity, and mem­bers of the same group often rest and so­cial­ize while touch­ing. Spec­tral tar­siers sit next to one an­other and in­ter­twine tails and are know to snug­gle.

Vi­sual com­mu­ni­ca­tion ap­pears to be most ef­fec­tive when group mem­bers are in close con­tact with one an­other. They com­mu­ni­cate by changes in fa­cial mus­cu­la­ture and body pos­ture. Folded ears seem to con­vey un­easi­ness, and a crouched pos­ture is taken when de­fen­sive. When ag­gres­sive, a tar­sier stands on its hind feet with its mouth open. (Bur­ton and Ni­etsch, 2010; Gron, 2010; Gursky, 2002; Gursky-Doyen and Supri­atna, 2010; MacK­in­non and MacK­in­non, 1980)

• Communication Channels
• visual
• tactile
• acoustic
• chemical

• Other Communication Modes
• duets
• choruses
• scent marks

• Perception Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

Spec­tral tar­siers feeds ex­clu­sively on live an­i­mals. They pri­mar­ily prey on fly­ing in­sects such as moths, lo­custs, bee­tles and ci­cadas. They oc­ca­sion­ally eat small ver­te­brates, such as lizards or bats. Spec­tral tar­siers lis­ten with their in­de­pen­dently mov­ing ears to lo­cate po­ten­tial prey. Once a prey item is tar­geted, a tar­sier am­bushes its prey with a sud­den lunge, grasps it with its long, slen­der fin­gers, and bites to kill it. The tar­sier then re­turns to its perch to con­sume its prey. This form of am­bush hunt­ing re­quires ex­cel­lent hand-eye co­or­di­na­tion. Spec­tral tar­siers can col­lect their prey out of the air, on the ground, or off leaves and branches. Tar­siers can eat 10% of their own body weight every 24 hours, and they drink water sev­eral times through­out the night.

Spec­tral tar­siers ap­pear to take ad­van­tage of the moon­light when for­ag­ing. This is an un­usual be­hav­ior, as most small, noc­tur­nal mam­mals ex­hibit lunar pho­bia as a preda­tor avoid­ance mech­a­nism. Tar­siers cope with this in­creased risk of pre­da­tion by for­ag­ing in groups. (Gron, 2010; Gursky, 2002; Mac­Don­ald, 2006; MacK­in­non and MacK­in­non, 1980; Shekelle and Salim, 2008)

• Primary Diet
• carnivore
  • eats terrestrial vertebrates
  • insectivore

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

Pre­da­tion

Po­ten­tial preda­tors of spec­tral tar­siers in­clude ar­bo­real snakes, civets, mon­i­tor lizards, owls and other rap­tors, and feral cats. If a preda­tor, par­tic­u­larly a snake, is iden­ti­fied, they emit an alarm call. This ini­ti­ates mob­bing be­hav­ior, in which nu­mer­ous tar­siers gather and ap­proach the preda­tor as a group, scream­ing, lung­ing, and even bit­ing. Mob groups usu­ally con­sist of adult males from neigh­bor­ing groups, which is in­ter­est­ing as most spec­tral tar­sier so­cial groups only con­tain one ter­ri­to­r­ial adult male. This group­ing by neigh­bor­ing males sug­gests some form of co­op­er­a­tion among males dur­ing preda­tor mob­bing. If spec­tral tar­siers spot a bird of prey such as an owl, they sound an alarm call and par­tic­i­pate in avoid­ance mech­a­nisms such as mov­ing fur­ther away from the preda­tor and in­creas­ing cryp­tic be­hav­iors. (Gursky, 2005; MacK­in­non and MacK­in­non, 1980)

• Known Predators

  • arboreal snakes
  • civets
  • monitor lizards
  • owls
  • other raptors
  • feral cats

Ecosys­tem Roles

Spec­tral tar­siers may in­flu­ence pop­u­la­tions of their in­sect prey. They host in­testi­nal par­a­sites such as hook­worms and tape­worms. A re­lated species, Tar­sius ba­canus, hosts var­i­ous species of in­testi­nal worms such as Monil­i­formes tar­sii and Monil­i­formes echi­noseroxi; spec­tral tar­siers may be sus­cep­ti­ble to these par­a­sites. (Roberts, 1994)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Tar­sius tar­sier is im­por­tant to evo­lu­tion­ary bi­ol­o­gists and tax­on­o­mists as it is thought to be the most prim­i­tive of the tar­siers; there­fore it can be stud­ied to bet­ter un­der­stand pri­mate evo­lu­tion.

Spec­tral tar­siers are pri­mar­ily in­sec­tiv­o­rous, and may aid in the mit­i­ga­tion of in­sect pest pop­u­la­tions. Tar­siers also draw tourists to the In­done­sian is­lands and are ben­e­fi­cial to hu­mans fi­nan­cially as a form of eco­tourism. Tar­siers are oc­ca­sion­ally kept as pets, though they do not sur­vive well. (MacK­in­non and MacK­in­non, 1980)

• Positive Impacts
• pet trade
• ecotourism
• research and education
• controls pest population

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Spec­tral tar­siers kept as pets fre­quently host par­a­sites, such as in­testi­nal worms, that can be trans­mit­ted to hu­mans. Tar­siers do not sur­vive well as pets due to their high en­er­getic diet re­quire­ments. (Mac­Don­ald, 2006)

• Negative Impacts
• injures humans
  • carries human disease

Con­ser­va­tion Sta­tus

Spec­tral tar­siers are cur­rently abun­dant on the is­land of Su­lawesi, par­tic­u­larly among the north­ern penin­sula with a den­sity rang­ing from 156 to 800 in­di­vid­u­als per square kilo­me­ter. How­ever, this species is still con­sid­ered vul­ner­a­ble due to habi­tat de­struc­tion caused by log­ging. Log­ging re­duces tar­sier den­si­ties through the de­struc­tion of pre­ferred sleep­ing sites such as stran­gler fig trees. Stran­gler figs are re­moved from hu­man-uti­lized forests be­cause they are seen as a threat to other com­mer­cially valu­able trees. (Gron, 2010; Shekelle and Salim, 2008)

• IUCN Red List

  Vulnerable
  More information

• IUCN Red List

  Vulnerable
  More information

• CITES

  Appendix II

Other Com­ments

Tar­siers have re­cently moved from the sub­or­der Prosimii to the sub­or­der Hap­l­or­rhinii, al­though their clas­si­fi­ca­tion is still under de­bate. Tar­sius spec­trum (Pal­lus, 1778) is a ju­nior syn­onym for Tar­sius tar­sier (Erxleben, 1777).

Fos­sil rel­a­tives of tar­siers have been found in Asia, Eu­rope, North Amer­ica, and Africa, how­ever mod­ern tar­siers are re­stricted to a few is­lands in South­east Asia. They have likely oc­cu­pied this re­gion for more than 40 mil­lion years.

Tar­siers get their name from their elon­gated tarsal re­gion. In the past, tar­siers were used as a totem an­i­mal of the head-hunt­ing Iban peo­ple of Bor­neo. (Mac­Don­ald, 2006; Napier and Napier, 1985; Shekelle and Salim, 2008)

Con­trib­u­tors

Ken­zie Mogk (au­thor), Uni­ver­sity of Man­i­toba, Jane Wa­ter­man (ed­i­tor), Uni­ver­sity of Man­i­toba, Gail Mc­Cormick (ed­i­tor), An­i­mal Di­ver­sity Web Staff.

Ref­er­ences

Bur­ton, J., A. Ni­etsch. 2010. Ge­o­graph­i­cal vari­a­tion in duet songs of Su­lawesi tar­siers: Ev­i­dence for new cryp­tic species in south and south­east Su­lawesi. In­ter­na­tional Jour­nal of Pri­ma­tol­ogy, 31: 1123-1146.

Gron, K. 2010. "Pri­mate Fact­sheets: Tar­sier (Tar­sius) Tax­on­omy, Mor­phol­ogy, & Ecol­ogy" (On-line). Pri­mate Info Net. Ac­cessed No­vem­ber 08, 2011 at http://​pin.​primate.​wisc.​edu/​factsheets/​entry/​tarsier/​taxon.

Gursky-Doyen, S. 2011. In­fan­ti­cide by a male spec­tral tar­sier (Tar­sius spec­trum). Pri­mates, 52(4): 385-389.

Gursky-Doyen, S. 2010. In­fra­spe­cific vari­a­tion in the mat­ing sys­tem of Spec­tral Tar­siers. In­ter­na­tional Jour­nal of Pri­ma­tol­ogy, 31: 1161-1173.

Gursky-Doyen, S., J. Supri­atna. 2010. In­done­sian Pri­mates. New York: Springer. Ac­cessed No­vem­ber 08, 2011 at http://​www.​springerlink.​com/​content/​n17q23/#​section=651387&​page=3&​locus=48.

Gursky, S. 2010. Dis­per­sal Pat­terns in Tar­sius spec­trum. In­ter­na­tional Jour­nal of Pri­ma­tol­ogy, 31: 117-131.

Gursky, S. 2005. Preda­tor mob­bing in Tar­sius spec­trum. In­ter­na­tional Jour­nal of Pri­ma­tol­ogy, 26(1): 207-221.

Gursky, S. 2002. The be­hav­ioral ecol­ogy of the Spec­tral tar­sier, Tar­sius spec­trum. Evo­lu­tion­ary An­thro­pol­ogy, 11: 226-234.

Hi­rota, A., T. Hara, T. Hosoda, F. Hashizaki. 2011. Hand-rais­ing a Spec­tral Tar­sier (Tar­sius tar­sier) at the Ueno Zo­o­log­i­cal Gar­dens. Zoo Bi­ol­ogy, 30: 218-224.

Mac­Don­ald, D. 2006. The En­cy­clo­pe­dia of Mam­mals. New York: Facts on File.

MacK­in­non, J., K. MacK­in­non. 1980. The be­hav­iour of wild spec­tral tar­siers.. In­ter­na­tional Jour­nal of Pri­ma­tol­ogy, 1(4): 361-379.

McNab, M., P. Wright. 1987. Tem­per­a­ture reg­u­la­tion and oxy­gen con­sump­tion in the Philip­pine tar­sier Tar­sius syrichta. Phys­i­o­log­i­cal Zo­ol­ogy, 60: 596-600.

Napier, J., P. Napier. 1985. The Nat­ural His­tory of the Pri­mates. Great Britain: MIT Press.

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

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

Shekelle, M., A. Salim. 2008. "Tar­sius tar­sier" (On-line). In: IUCN 2012. IUCN Red List of Threat­ened Species. Ver­sion 2012.1. Ac­cessed No­vem­ber 08, 2011 at http://​www.​iucnredlist.​org/​apps/​redlist/​details/​21491/​0.

Shekelle, M., A. Ni­etsch. 2008. Pri­mates of the Ori­en­tal Night. West Java: West Java : In­done­sia In­sti­tute of Sci­ences, Re­search Cen­ter for Bi­ol­ogy.

Ulmer, F. 1960. A longevity record for the Min­danao tar­sier. Jour­nal of Mam­mal­ogy, 41: 512.

Wright, P., E. Si­mons, S. Gursky. 2003. Tar­siers: past, pre­sent, and fu­ture. United States of Amer­ica: Rut­gers Uni­ver­sity Press.