Until recently the conservation status of seven of the nine species of tarsier on the IUCN Red List was Data Deficient, and determining the status of these species has been a priority. In addition, there are believed to be numerous cryptic tarsier taxa. Tarsiers have been proposed as flagship species to promote conservation in the biogeographical region that includes Sulawesi and surrounding island chains. Therefore, identifying and naming cryptic tarsier species and determining their conservation status is not only a priority for tarsier conservation but also for regional biodiversity conservation. Two tarsier species, Tarsius sangirensis from Sangihe Island and Tarsius tumpara from Siau Island, occur within the Sangihe Islands, a volcanic arc stretching c. 200 km north from the northern tip of Sulawesi. The geographical information system database from The Nature Conservancy's Sulawesi Ecoregional Conservation Assessment was used in conjunction with field surveys to determine the conservation status of these two species. Our results show that both species are at risk from a small extent of occurrence and area of occupancy, small population size, high risk of volcanism, high human population density, fragmented populations (many of which are in marginal habitat), and lack of conservation areas for either species. In addition, there are no available ex situ conservation options. The Siau population is further threatened by hunting for bushmeat. Our recommendations are that T. sangirensis be categorized as Endangered and T. tumpara, which was included on the 2006–2008 list of the world's top 25 most endangered primates, as Critically Endangered on the IUCN Red List.

Surveys between 1995 and 1999 brought the number of mammal species known to occur on the remote Sangihe and Talaud islands, Indonesia, from 34 to 37, of which 30 are indigenous and 22 are bats. Populations of bear cuscus Ailurops ursinus and Sulawesi small cuscus Strigocuscus celebensis are represented by endemic subspecies, whilst five little-studied species (Talaud Islands flying fox Acerodon humilis, Sangihe tarsier Tarsius sangirensis, Sangihe squirrel Prosciurillus rosenbergi, short-tailed Talaud melomys Melomys caurinus and long-tailed Talaud melomys M. talaudium) are endemic to the archipelago. Two squirrel species were recorded on Sangihe for the first time: Sulawesi dwarf squirrel P. murinus and Sulawesi giant squirrel Rubrisciurus rubriventer. In total, eight species occurring on the islands are categorized as globally threatened on the 2000 IUCN Red List of Threatened Species. Habitat loss and hunting are the main threats on the Sangihe islands, where only 800 ha of primary forest remain. Large areas of Karakelang, in the Talaud Islands, are still forested, and a 24,669 ha wildlife reserve has been recently established. The main pressure facing mammal species on the Talaud Islands is hunting, particularly mist-netting of fruit bats for local consumption and trade. In order to control hunting and prevent further forest loss and degradation, future conservation efforts should focus on community-based conservation, in particular raising community awareness and increasing law enforcement. Two concurrent projects are now tackling some of these issues.