The species is found only on Siau Island (Indonesia), although it is conceivable that they are also present on some very small islands that are in close proximity to Siau and separated only by shallow ocean.
Habitat and Ecology
Tarsius tumpara has not been the subject of systematic study, but it has been surveyed in the wild by a team led by M. Shekelle (Shekelle et al. 2008), and Siau Island was surveyed by Riley (2002). By analogy with other wild Tarsier populations it is expected that this taxon is found in primary (although no tracts of primary forest have been found on Siau Island), secondary and mangrove forests, forest gardens, and a variety of other habitats of varying degrees of human disturbance that provide adequate shrubby cover. Shekelle and Salim (2009b) reported that their surveys found evidence of T. tumpara in only two places; on the shores of a small freshwater pond at the extreme southern end of the of the island, and on a steep cliff face along the east coast road where it runs next to the ocean. Numerous other sites that appeared promising turned up no evidence of the presence of tarsiers. There are reports that they can still be found high on the flanks of Mt Karengetang, near the caldera.
Tarsius tumpara is phylogenetically linked to other Eastern Tarsiers, from the Sulawesi biogeographic region. All of the species in this clade live in small, monogamous or polygamous groupings of 2-6. Anecdotal observations of T. tumpara, and those of its likely sister-taxon, T. sangirensis, indicate that these species 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-bodied arthropods, with some small vertebrates.
IUCN Red List Assessment
Red List Category
Red List Criteria
Listed as Critically Endangered because there has been a suspected reduction in population size of at least 80% over the past three generations, based on actual levels of exploitation and on the direct observations by local people living in proximity to the tarsiers, along with declines in the area of occupancy (perhaps as little as 19.4 km²) and quality of habitat. Criterion B is invoked because although a maximum extent of occurrence is 125 km² (based on the size of Siau Island, along with two tiny islets where its presence has not been documented), it is in reality much less than this 100 km², if the cone of the active volcano is excluded.
Shekelle and Salim (2009a) used remote sensing of remaining habitat and population density estimates from studies of other tarsier taxa to estimate the remaining population as being 1,358–12,470 individuals. The large range is a result of a large number of unknown pixels (obscured by clouds) in the GIS data set. Field surveys indicate no remaining primary habitat, however. Local people reported considerable declines of numbers since the late 1990s (Shekelle and Salim 2009b).
The primary threat to this taxon is that its range is restricted to one small, volcanic island. The volcano, Mt. Karengentang, is active and dominates more than 50% of its geographical range. This threat is exacerbated by a relatively large human population (311 people/km²) that has converted virtually all of the primary habitat to some form of human use (Shekelle and Salim 2009a, 2009b). In these ways, Tarsius tumpara faces a set of threats similar to those faced by T. sangirensis, but the threats are more acute for T. tumpara: a smaller island, a more active volcano, and higher human population density. Most troubling, however, are numerous credible reports that the local human population regularly eats tarsiers, up to 5-10 animals at a sitting, and that tarsiers have been extirpated from areas where they were common as recently as 10 years ago.
Tarsius tumpara is considered to be one the world’s 25 most endangered primates by the IUCN Species Survival Commission Primate Specialist Group (Shekelle and Salim 2007, 2009b).
Siau Island tarsier
Its existence as a distinct taxon was predicted by the hybrid biogeographic hypothesis for Sulawesi. The rationale was that a geographic discontinuity existed between the northern tip of Sulawesi, and the population of tarsiers on Sangihe Island (the Sangihe tarsier Tarsius sangirensis), approximately 200 kilometres (120 mi) to the north. In between, lay very deep oceans and three island clusters, Biaro, Tagulandang/Ruang, and Siau. Like Sangihe Island, itself, each of these three island clusters are a part of the Sangihe Island volcanic arc. Volcanic arcs, like the Galapagos and Hawaiian Island chains, feature islands that erupt from the ocean floor. In such circumstances, islands form independently, are colonized independently, and remain geographically isolated. These characteristics lead to high levels of endemism. The presence of tarsiers on the most distant island group in the Sangihe volcanic arc (i.e. Sangihe island), led to curiosity about the presence of tarsiers on the other islands in the chain. Each of the three island clusters mentioned above were surveyed for the presence of tarsiers in 2004 and 2005, but tarsiers were only observed on Siau.
It was furthermore elaborated upon that the original description of T. sangirensis included mention of a specimen from Siau in the Dresden Museum. Thus it was argued for further investigations of the Siau tarsier to see if it was taxonomically separable from T. sangirensis.
- Shekelle, M. & Salim, A. (2011). "Tarsius tumpara". IUCN Red List of Threatened Species. Version 2011.2. International Union for Conservation of Nature. Retrieved 18 January 2012.
- Shekelle, M.; Groves, C.; Merker, S.; Supriatna, J. (2008). "Tarsius tumpara: A new tarsier species from Siau Island, North Sulawesi". Primate Conservation 23: 55–64. doi:10.1896/052.023.0106.
- Shekelle, M.; Leksono, S. M. (2004). "Rencana konservasi di Pulau Sulawesi: dengan menggunakan Tarsius sebagai flagship spesies (Conservation strategy in Sulawesi Island using Tarsius as flagship species)". Biota 9 (1): 1–10.
- Brandon-Jones, D.; Eudey, A. A.; Geissmann, T.; Groves, C. P.; Melnick, D. J.; Morales, J. C.; Shekelle, M.; Stewart, C. -B. (2004). "Asian primate classification". International Journal of Primatology 25: 97. doi:10.1023/B:IJOP.0000014647.18720.32.
- Shekelle, M.; Meier, R.; Indrawan, M.; Maryanto, I.; Salim, A.; Supriatna, J.; Andayani, N. (2007). "When "not extinct" is not good news: Conservation in the Sangihe Islands". Conservation Biology 21 (1): 4–5. doi:10.1111/j.1523-1739.2006.00622_1.x. PMID 17298499.
- Mittermeier, R.A.; Wallis, J.; Rylands, A.B.; Ganzhorn, J.U.; Long Yongcheng, J.F.; Williamson, E.A.; Palacios, E.; Heymann, E.W.; Kierulff, M.C.M., eds. (2009). Primates in Peril: The World's 25 Most Endangered Primates 2008–2010 (PDF). Illustrated by S.D. Nash. Arlington, VA.: IUCN/SSC Primate Specialist Group (PSG), International Primatological Society (IPS), and Conservation International (CI). pp. 1–92. ISBN 978-1-934151-34-1.
Further reading 
- Shekelle, M.; Salim, A. (2009). "An acute conservation threat to two tarsier species in the Sangihe Island chain, North Sulawesi, Indonesia". Oryx 43: 419–426. doi:10.1017/S0030605309000337.