long-nosed monkey

The Proboscis Monkey (Nasalis larvatus) is a uniquely dramatic primate endemic to Borneo. Recognized for its large, pendulous nose (especially in males) and reddish-brown to gray coat, this arboreal species excels in swimming and often escapes predators by plunging into water. Adults display strong sexual dimorphism, with males reaching ~21 kg and females ~10 kg. Socially, they form one-male, multi-female groups with occasional all-male bands, and move using quadrupedalism, leaping, and swimming. Their diet is specialized for leafy material—processed using their multi-chambered gut to digest tough foliage. Populations are fragmented yet remain stable in protected areas, with global estimates below 10,000 individuals. However, their unique habitat needs—river-adjacent forests and peat swamps—and shrinking ranges due to logging and agricultural expansion compromise their long-term outlook. Conservation strategies focus on habitat protection, law enforcement, and sustainable land-use planning.