Siau Island tarsier [SEP] IUCN conservation status
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".
The Sangihe Islands are known for their critically endangered avifauna, and
concerns about the conservation status of the Siau Island tarsier grew before its formal description.
The Siau Island tarsier was selected for the list of "The World's 25 Most Endangered Primates" by the IUCN Species Survival Commission, Primate Specialist Group.