The National Parks Board (NParks) is studying the long-tailed macaque, the Raffles' banded langur and the sunda slow loris.
In partnership with the National University of Singapore, NParks will begin studying the long-tailed macaque in January next year.
The three-year study aims to better understand how the species interacts with the Raffles' banded langur by comparing their demographics, behaviour, diet and more.
This will let NParks formulate conservation and management strategies for these primates by assessing where habitat connectivity can be improved, and where mitigation methods are needed to reduce human-wildlife interactions with the long-tailed macaques.
The study will take place islandwide for the macaques and in nature reserves and buffer parks for the Raffles' branded langur.
NParks has also been studying the sunda slow loris in nature reserves and buffer parks to gather more information about its spatial distribution, habitat preferences and behavioural patterns.
Future research will study population size, home range and activity patterns.
The Raffles' Banded Langur Working Group comprising Wildlife Reserves Singapore, NParks and universities from Singapore and Malaysia, developed a species action plan in 2016 for the conservation of the langurs.