Conservation Status of the Spectral Tarsier Tarsier spectrum: Population Density and Home Range Size

Abstract

As part of a larger study of the behavioral ecology of the spectral tarsier, Tarsius spectrum, a population census was conducted. A modified form of the fixed point count and quadrat census methods was conducted within a 1-km² area in Tangkoko Dua Saudara Nature Reserve, in northern Sulawesi, Indonesia. In 25 one-hectare plots, 14 groups were located, containing a total of 39 individuals. Therefore, the mean number of groups per ha was 0.56 and the mean number of individuals per ha was 1.56. The number of groups for the entire sampled area (100 ha) was calculated to be 56, while the total population within the sampled area was calculated to be 156 (i.e. 156/km²). Group size, defined as the number of individuals sharing a sleeping site, varied from 2 to 6 individuals. Group composition varied from 1 adult of each sex to 1 adult male and 2 adult females and their offspring. Fourteen percent of groups contained more than 1 adult female. In one of the groups with two adult females, both females gave birth to infants. The home ranges of 13 individuals, obtained using radio telemetry, were between 1.6 and 4.1 ha, with an average size of 2.3 ha for females and 3.1 ha for males. Results from this study indicate that spectral tarsiers are still relatively abundant at Tangkoko Dua Saudara Nature Reserve. Nonetheless, the limited geographic distribution of this species, the lack of information on its relative abundance in other areas of its range, as well as the high rate of habitat disturbance throughout its range, suggests that the conservation status of the spectral tarsier should be changed from indeterminate to vulnerable.

Allocare in a Nocturnal Primate: Data on the Spectral Tarsier, Tarsius spectrum

“…The reserve comprises approximately 9,000 ha, with a sea boundary of 12 km. It exhibits a full range of forest types from beach formation forest, to lowland forest, to mossy cloud forest [35,36,[45][46][47][48]. The majority of the reserve is disturbed by old clearing activities and/or selective harvesting.…”

“…The spectral tarsier, Tarsius spectrum, is a small, nocturnal, prosimian primate found exclusively on the island of Sulawesi in Indonesia [27,35,36,48]. It displays a number of characteristics that are frequently observed in the small-bodied New World primates that exhibit extensive allocaretaking behavior.…”

“…It displays a number of characteristics that are frequently observed in the small-bodied New World primates that exhibit extensive allocaretaking behavior. Like Aotus and Callicebus, which exhibit extensive allocaretaking behavior, spectral tarsiers are small-bodied (mean adult female weight 108 g, n = 11, SD + 6.09), produce a single large infant (22% adult weight, n = 2), and are primarily monogamous (85%, n = 33) in their social structure [27,[35][36][37][38]48]. In Aotus and Callicebus, some researchers have hypothesized that the presence of extensive allocare behavior by adult males and other group members is related to the high infant/adult weight ratios observed in these species.…”

Population mapping of gibbons in Kalimantan, Indonesia: correlates of gibbon density and vegetation across the species’ range

“…(3) Fixed-point counts allow quick, time-efficient surveys with more reliable results than a line transect survey conducted within the same time frame (Nijman & Men ken 2005). This method has proved efficient in several primate surveys (Brockelman & Srikosama tara 1993, Gursky 1998, Estrada et al 2002, 2004, Nijman 2004, Cheyne et al 2008, Hamard et al 2010, allowing the comparison of their results across sites. Occupancy is not the best technique for obtaining de tailed population density estimates, which was the aim of these surveys, hence the use of triangulation.…”

Living together in the night: abundance and habitat use of sympatric and allopatric populations of slow lorises and tarsiers

“…Slow lorises possess this layer of tissue (Fleagle 1999), unlike tarsiers (Schwartz 2003). Most tarsier studies have focused on the Sulawesi species, which are easily detected by their regular duets during dusk and dawn (Gursky 1998). Western tarsiers are not known to vocalize regularly, making them hard to detect; they were detectable from a red eye glare when a red filter was used.…”