Spectral Tarsier (Tarsius spectrum)


MORPHOLOGY:
This nocturnal species has large eyes and large ears that are mobile. This species lacks a tapetum lucidum in the eyes, which are usually found in nocturnal animals. The spectral tarsier has a special adaptation in its neck vertebrae to help it turn its head 180 degrees. It needs to do this because its eyes can not move. The spectral tarsier has a dental formula of 2:1:3:3 on the upper jaw and 1:1:3:3 on the lower jaw (Nowak, 1999). This species has relatively small upper canines (Nowak, 1999). This species receives its name from the elongated tarsus bone. The tail of this species is naked except for the last half to third, which has long hair, and on the end there is a tuft of hair (Rowe, 1996). This species has two grooming claws on each foot. The average body mass for males is around 125 grams, and for females it is around 110 grams.

RANGE:
The spectral tarsier is found in the country of Indonesia, on the island of Sulawesi and the nearby islands of Sangihe, Peleng, and Salayer (Nowak, 1999). This species lives in a variety of habitats, including primary and secondary forests, coastal forests, and mangrove forests. This species is found at altitudes from sea level to 4000 feet (Nietsch and Niemitz, 1991). This species has also been reported to have been found in urban gardens (Nietsch and Niemitz, 1991).

ECOLOGY:
This nocturnal species is a carnivorous species. The spectral tarsier mainly eats insects. Of the insects consumed includes: moths, termites, crickets, dragonflies, cockroaches, and beetles (MacKinnon and MacKinnon, 1980). This species catches cryptic prey by sight and moving prey by sound first then the individual fixates the prey with sight (MacKinnon and MacKinnon, 1980). If a prey item is on the ground this species will pounce on it then move to a perch before eating it (MacKinnon and MacKinnon, 1980). If a prey item is in the foliage the spectral tarsier will grab at with its hands then move to another perch before eating it (MacKinnon and MacKinnon, 1980). This species hunts for prey below 9 meters and will often hunt on the ground (Rowe, 1996). The family groups will hunt for prey together and remain in visual contact (Rowe, 1996).

Group sizes in this species range from 2 to 6 individuals (Nietsch and Niemitz, 1991). Sleeping trees for this species tend to be found at the territorial borders (Nietsch and Niemitz, 1991). The core area for the group is used exclusively by the group (Nietsch and Niemitz, 1991). During heavy rains this species shelters itself by sitting under large leaves (MacKinnon and MacKinnon, 1980). This species becomes active about 20 minutes after sunset (MacKinnon and MacKinnon, 1980). Adults of the group tend to range further during the night than juveniles (MacKinnon and MacKinnon, 1980). Group home ranges tend to slightly overlap with other groups (MacKinnon and MacKinnon, 1980).

MacKinnon and MacKinnon (1980) found four categories of sleeping sites for the spectral tarsier:

In primary forests, sleeping sites of type 4 is the most common, while in open areas type 1 is the common type of sleeping site (MacKinnon and MacKinnon, 1980). All of the sleeping sites have the following characteristics: multiple exits to escape from predators, darkness, protection from wind and rain, and multiple surfaces to grasp when sleeping (MacKinnon and MacKinnon, 1980). The spectral tarsier sleeps in groups (MacKinnon and MacKinnon, 1980). The most popular tree used for sleeping in is Ficus caulocarpa (Gursky, 1998). The mean height of sleeping trees is 23 meters (Gursky, 1998). The spectral tarsier uses the same sleeping site each day (Sussman, 1999).

The only predators of this species are feral cats (MacKinnon and MacKinnon, 1980). Spectral tarsiers probably defend themselves from feral cats by tasting bad (MacKinnon and MacKinnon, 1980).

LOCOMOTION:
This species is a vertical clinger and leaper. Having the elongated tarsus helps them in leaping. Also the fibula and tibia is fused on the lower third part going towards the foot which also helps in leaping. The mean leap length for this species is 1.4 meters (MacKinnon and MacKinnon, 1980). This species also moves by climbing, hopping, or a slow quadrupedal type movement much like that found in lorises (MacKinnon and MacKinnon, 1980). When hunting and traveling the spectral tarsier uses vertical supports 4 centimeters in diameter and less than 3 meters high (MacKinnon and MacKinnon, 1980). However when resting, sleeping, or grooming this species is found higher up in the forest, uses supports of larger diameters and the are diagonal or horizontal (MacKinnon and MacKinnon, 1980).

SOCIAL BEHAVIOR:
The basic group of the spectral tarsier is made up of the mated pair and their offspring. However unlike the Horsfield's tarsier, Tarsius bancanus, this species sleeps and forages in these groups. Gursky (1998) found that this species is also found in polygynous groups. In polygynous groups it was found that all adult females of the group gave birth (Gursky, 1998). Pairs are territorial, chasing other conspecifics out of their home range (MacKinnon and MacKinnon, 1980). Females will stay in their groups until they are adults, while males will emigrate when they are still juveniles (MacKinnon and MacKinnon, 1980). In this species the mother will park her infant in the tree in which she is foraging in, and this occurred when the infants were between the ages of 3 and 6 weeks (Gursky, 1996).

Allomaternal care is found in this species and includes: infant transporting, food sharing, baby-sitting, grooming, and playing (Gursky, 2000). Allomaternal care does not occur until the infant is of 3 weeks of age because before that the mother separates herself from the rest of the group not allowing contact with her infant (Gursky, 2000). Infant transport by other group members has only been found to have been done by subadult females (Gursky, 2000). This transport occurred when the infant fell from its parked position, and the subadult female transported the infant in its mouth (Gursky, 2000). Food sharing has also only been seen to occur between infants and subadult females (Gursky, 2000). Adult males, subadult males, and subadult females all were found to groom and play with the infant, although subadult females were in physical contact with infants more than adult males and subadult males (Gursky, 2000). It is interesting to note that mothers rarely if ever played with their infants (Gursky, 2000). Adult males, subadult males, and subadult females were all found to baby-sit infants, although subadult females did this at a higher frequency (Gursky, 2000). Adult males, subadult males, and subadult females emitted a higher number of alarm calls when an infant is in the group compared to as when an infant is not present (Gursky, 2000). Subadult females may provide allomaternal care so as to learn to care for their own offspring and/or to be able to remain on the parental territory (Gursky, 2000). Adult males might not be able to participate in allocare because they spend a large amount of time patrolling the territory and scanning for predators (Gursky, 2000). Other members of the group tend to stay away from the infant when the mother is near the infant (Gursky, 1994).

VOCAL COMMUNICATION:
male-female duet: this behavior is used to bring the family together, family cohesion and for territory marking. Males will emit a regular series of squeal barks while the female of the pair will punctuate each call with a series of squeaks that rise in pitch and that end in a trill (MacKinnon and MacKinnon, 1980). For the female song, the peak frequency will decrease from the start of the series to the end (Nietsch, 1999). The pair may adjust their calls to match that of their mates by acceleration or deceleration of call rate (Nietsch, 1999). This call occurs in the morning around dawn (Nietsch and Kopp, 1998). This call is used to advertise the pair bond of the male and female to territorial intruders (Nietsch and Kopp, 1998).

OLFACTORY COMMUNICATION:
Olfactory communication is important for the spectral tarsier. It is used to communicate territory demarcation.

scent mark with circumoral gland: This is where adults will scent mark each other using the gland surrounding their mouths (MacKinnon and MacKinnon, 1980).

scent mark with epigastric gland: This is where males will scent mark their mates and substrates with the gland on their abdomens (MacKinnon and MacKinnon, 1980).

scent mark with the anogenital region: This is when females will mark their mates or tree branches with their swollen vulva (MacKinnon and MacKinnon, 1980).

urine mark: This where spectral tarsiers of both sexes and all ages groups will mark tree branches with urine (MacKinnon and MacKinnon, 1980). Individuals will use larger size trees (7.1 centimeters) when performing this behavior (Niemitz, 1984). The areas that are marked tend to be around 1.08 meters in height (Niemitz, 1984). This behavior serves to demarcate territories (Niemitz, 1984).

VISUAL COMMUNICATION:

TACTILE COMMUNICATION:

REPRODUCTION:
This species gives birth to a single offspring twice a year, once at the beginning and the end of the rainy season, April-May and November-December (MacKinnon and MacKinnon, 1980). The mother carries the infant around in her mouth.

REFERENCES:
Burton, F. 1995. The Multimedia Guide to the Non-human Primates. Prentice-Hall Canada Inc.

Gursky, S.L. 1994. Infant care in the spectral tarsier (Tarsius spectrum) Sulawesi, Indonesia. International Journal of Primatology. Vol. 15(6), 843-853.

Gursky, S.L. 1996. Infant parking behavior in the spectral tarsier. (abstract) American Journal of Physical Anthropology. Suppl. 22, 118.

Gursky, S. 1998. Conservation status of the spectral tarsier Tarsius spectrum: Population density and home range size. Folia Primatologica. Vol. 69(suppl 1), 191-203.

Gursky, S. 2000. Allocare in a nocturnal primate: Data on the spectral tarsier, Tarsius spectrum. Folia Primatologica. Vol. 71, 39-54.

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

Niemitz, C. 1984. An investigation and review of the territorial behaviour and social organisation of the genus Tarsius. in Biology of Tarseirs. ed. C. Niemitz. Gustav Fischer Verlag: Stuttgart.

Nietsch, A. 1999. Duet vocalizations among different populations of Sulawesi tarsiers. International Journal of Primatology. Vol. 20(4), 567-583.

Nietsch, A. and Kopp, M.L. 1998. Role of vocalization in species differentiation of Sulawesi tarsiers. Folia Primatologica. Vol. 69(suppl 1), 371-378.

Nietsch, A. and Niemitz, C. 1991. Use of habitat and space in free-ranging Tarsius spectrum. (abstract). Primate Report. Vol. 31, 27-28.

Nowak, R.M. 1999. Walker's Primates of the World. The Johns Hopkins University Press: Baltimore.

Rowe, N. 1996. The Pictorial Guide to the Living Primates. Pogonias Press: East Hampton, New York.

Sussman, R.W. 1999. Primate Ecology and Social Structure: Vol. 1 Lorises, Lemurs, and Tarsiers. Pearson Custom Publishing.

Last Updated: April 17, 2007.
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