Habitat and Ecology
This population has not been studied systematically in the wild, but was surveyed by Shekelle and associates (Shekelle et al. 1997, Shekelle 2003) and Riley (2002). Riley remarked that T. sangirensis has a preference for primary forest, but may occur in secondary habitats including sago swamps, scrub, nutmeg plantations, coconut plantations, and secondary forest growth. These results are similar to those of Shekelle and associates, except that Shekelle did not encounter any in primary forest, and Shekelle and Salim (2009) indicate that it is very unlikely that any primary forest now remains on the island. A study of Tarsius dentatus on Sulawesi by Merker et al. (2005, also Merker and Yustian 2008) showed that they were able to occupy agricultural land as long there were remnant patches of forest or dense shrubbery, although group sizes were smaller and population densities were considerably lower (less than half) than was found for virtually undisturbed old-growth forest (estimated densities 268 individuals/km² vs. 45 individuals/km²).
Like other Eastern Tarsier species from the Sulawesi biogeographic region, this species lives in small, monogamous or polygamous groupings of 2–6. It might sleep in dispersed social groups, particularly in disturbed habitat, and that this might be a response to predation, particularly by humans and human commensals, such as feral cats and dogs. Merker (2006) studied home range size in T. dentatus and found it to vary, depending on the degree of human disturbance, with home range size increasing with the degree of disturbance. Its diet is mostly large arthropods and some small vertebrates.
IUCN Red List Assessment
Red List Category
Red List Criteria
Listed as Endangered as Tarsius sangirensis is known only from Sangihe Island which is 547 km², its range is severely fragmented, and there is ongoing decline in the extent and quality of its habitat.
- 2008Endangered(IUCN 2008)
- 2000Data Deficient
- 1996Data Deficient
Shekelle and Salim (2009) argue that the chief threat to tarsiers on Sangihe Island is habitat loss. One major driver of habitat loss is the clearing of forests and forest gardens for more intensive agriculture where underbrush is cleared, such as coconut monocrop, coconut/chocolate, nutmeg, and others (M. Shekelle pers. comm. 2010). Riley (2002), however, did not think that habitat loss was a major threat, given their presence in a variety of secondary habitats. This discrepancy emphasizes the need to determine the suitability of secondary habitats for sustainable tarsier populations. The volcano on Sangihe Island, Mt Awu, is active and one of the deadliest in Indonesia, and the human population density on the island is very high (260 people km-²) (Shekelle and Salim 2009). There is practically no primary forest left and there are no protected areas in its range (Shekelle and Salim 2009).
The taxon has been protected by national law since 1931, and is listed in CITES Appendix II. Two conservation initiatives begun in 2002 are serving to establish management systems on this archipelago and to educate its people on the environmental and conservation problems that the islands face, including those resulting from forest management and hunting (Riley 2002) (see Whitten 2006).
The Sangihe tarsier (Tarsius sangirensis), also known as Sangihe Island tarsier, is a small primate found on Sangir Island, which is located about 200 kilometers north-east of the island of Sulawesi in Indonesia. In 2008 a population of the Sangihe tarsier was split off as a distinct species, the Siau Island tarsier (Tarsius tumpara).
It was first assigned species status in 1896 by Adolf Meyer. It was later classified as a subspecies of the spectral tarsier T. spectrum by Hill and remained so until recently. Today it is recognized as a distinct species. The 2008-described Siau Island tarsier, Tarsius tumpara, from Siau Island was formerly considered a population of the Sangihe tarsier. There is still much debate on what is considered a species and a subspecies in the family Tarsiidae.
The large, round, forward-facing, pale-chestnut-colored eyes and elongated digits and tarsus are basic characteristics of the Sangihe tarsier. It is a very small primate weighing between 100 and 120 grams. The orbit is closed laterally by the post orbital bar. The lower jaw is V-shaped. It contains primitive teeth with a dental formula of I.2/1, C.1/1, P.3/3, M3/3. It has sharp teeth, since it strictly eats animal matter. The best way to determine this species is by the amount of fur on its tail and its acoustics, which are both distinctly different when compared to other tarsiers. Its tail is long and sparsely covered with fur dorsally and does not have scales underneath. The tails are very long compared to body size and are used for support while stationary but are not truly prehensile in nature. Upper pelage is yellowish brown with dark-grey bases. Lower parts of it are a dullish-white with a light-grey base. Its eyes are immobile but it has the ability to rotate its head 180 degrees.
Distribution and habitat
The Sangihe tarsier is endemic to the Sangihe Islands in Indonesia which is only 547 km2. It favors primary-growth forest but also fares well in secondary-growth forest. It also has been found in scrub habitats, coconut plantations, and in some cases agricultural areas. However, researchers are not sure if the populations found in agricultural areas are due to source-sink dynamic. All tarsiers live within 10 latitudinal degrees of the equator and require humid conditions, at least 50% humidity.
Behaviour and ecology
The mating pattern is monogamous or polygamous. It tends to be solitary or lives in small groups of 2–6. Groups mainly consist of the parents and offspring. Little is known about their specific mating patterns and reproduction development. What is known is based on better-documented species. It normally gives birth to a single offspring. There is little sexual dimorphism. It is a nocturnal species, which makes it even harder to document. Most tarsiers are relatively silent creatures and only make chirping sounds. Chirping can be mostly heard when males are trying to mate with females. Most of its communication is through scent, such as urine.
It eats mainly insects such as grasshoppers and beetles. It is occasionally seen eating small vertebrates like lizards. Tarsiers are the only know primates that are completely carnivorous. The digestive tract is very simple and short. It does not forage for insects like other insectivores but instead sits and waits. Once prey is spotted it will use it hands to grab it or leap and catch it.
The Sangihe tarsier is listed as endangered on the IUCN Red List. It is listed as an Appendix II species under CITES. Currently there are no specific conservation programs for this species of tarsier. There is also a lack of nature reserves located in its native land. It is very difficult to have any type of ex-situ conservation for this species, since it does not fare well outside their natural habitat. Since little is known about the species' reproduction patterns, there are not any breeding programs currently. Shekelle and Salim made some proposals on better protection for this species along with the Siau Island tarsier. Such actions include more investments on improving ex-situ conservation, mimic sanctuaries found for a subspecies of the Philippine tarsier Carlito syrichta fraterculus along with tarsier-tracking activities. Some of the above would increase ecotourism in the area and improve economics in the area. The authors also recommend increasing awareness of the species and advising people on how to better manage their lands to improve chances of the survival of the species.
The population is thought to be between 1,505 and 52,734. Accurate numbers are hard to estimate due to cloud coverage over its range. Some of its natural threats include birds, snakes, and the giant civet. Mount Awu can also be considered a natural threat as well, since it is an active and deadly volcano on the island. Anthropogenic causes include habitat loss or fragmentation, the introduction of cats and dogs to the island, population density increases in its territory, and pet trade.
|Wikispecies has information related to: Sangihe tarsier|
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- Shekelle, M. & Salim, A. (2011). "Tarsius sangirensis". IUCN Red List of Threatened Species. Version 2011.2. International Union for Conservation of Nature. Retrieved 18 January 2012.
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