Proboscis Monkey Survey In Sulaman Lake Forest Reserve, Tuaran, Sabah

Abstract

Surveying primate populations is important for understanding their distribution and abundance, providing baseline data to guide conservation planning and future monitoring. This is particularly relevant for threatened species such as the proboscis monkey (Nasalis larvatus), an iconic Bornean endemic whose population status remains poorly documented in many parts of its range. As part of a scientific expedition for the proposed extension of the Kinabalu UNESCO Global Geopark (KUGGp), a brief boat-based proboscis monkey survey was conducted from 21st to 24th April 2025 in the Sulaman Lake Forest Reserve (SLFR), Tuaran, Sabah. No proboscis monkeys were directly sighted during the survey, although a few solitary long-tailed macaques (Macaca fascicularis) were observed. Local residents, however, reported that a small group of six to seven proboscis monkeys is found within an isolated patch of mangrove forest along the Papat River in SLFR, although sightings are rare. This remnant mangrove habitat, despite being disturbed and highly fragmented, appears to support this elusive group, highlighting its conservation value. Yet the rarity of sightings suggests that the group may be close to its ecological limit, increasing the risk of local extinction if further habitat loss occurs. Inclusion of SLFR in the KUGGp expansion could help strengthen long-term protection and management efforts for this species in the area.