Proboscis Monkey (Nasalis larvatus)

Overview

The Proboscis Monkey is a Bornean endemic primate, easily recognizable by its large, pendulous nose and reddish-brown fur. It is primarily found in coastal mangroves and riverine forests, including areas around Tawau.

Habitat & Ecology

Proboscis Monkeys are highly adapted to riverine and mangrove ecosystems. They are excellent swimmers and can often be seen crossing rivers. Mangrove roots provide shelter and abundant food sources, including leaves, fruits, and seeds.

• Preferred areas: lowland rivers, estuaries, and mangrove forests.
• Social structure: live in groups of 10 - 20 individuals, led by a dominant male.
• Activity: mostly active during the day, resting at night in tall mangrove trees.

Behavior & Diet

These monkeys are folivorous, feeding mainly on leaves, fruits, and seeds. Their large stomachs allow them to digest fibrous leaves efficiently. They are often seen jumping between mangrove branches or swimming across rivers to forage.

Distinguishing Uniqueness: Proboscis vs. Red Leaf Monkey

Feature	Proboscis Monkey	Red Leaf Monkey
Nose	Large, pendulous nose (esp. males)	Small, flat nose
Habitat	Mangroves, rivers, estuaries	Hill & dipterocarp forests
Body	Pot-bellied, webbed feet, strong swimmers	Slim, agile climbers
Diet	Leaves, fruits, seeds (fibrous digestion)	Tender young leaves, shoots
Social Calls	Loud honks & nasal sounds	Softer calls, less resonant

Where to See Proboscis Monkey in Tawau & East Coast

• Kuala Tawau mangroves  -  Frequent encounters along tidal waterways.
• Pulau Sebatik mangroves  -  Occasional river-crossing groups.
• Kinabatangan River (Sandakan region)  -  Larger populations along riverbanks.

Conservation Efforts & NGOs

• The conservation of Proboscis Monkeys in Sabah thrives through the synergy of research, academia, and grassroots action.
•  Henry Bernard and John Sha provide the essential foundation by documenting population status and threats in East Sabah, ensuring conservation strategies are grounded in evidence.
• Building on this, Joseph Tangah and his team at Universiti Malaysia Sabah investigate isolated populations and the impacts of mangrove degradation, highlighting the ecological consequences of habitat fragmentation and the urgent need for restoration.
• Complementing these scientific efforts, Tawau's local volunteers bring conservation to life through mangrove replanting and awareness campaigns. Their work fosters respect for the monkeys as neighbors rather than tourist commodities, embedding conservation within community values. Together, these groups form a powerful alliance: researchers define the threats, academics explain the ecological impacts, and volunteers act to restore and protect habitats. Their combined achievements exemplify how collaboration across disciplines and communities safeguards Sabah's natural heritage.

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  Henry Bernard & John Sha  -  Researchers documenting Proboscis population status and threats in East Sabah.

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  Joseph Tangah & team (Universiti Malaysia Sabah)  -  Studied isolated Proboscis populations and mangrove degradation impacts.

The Proboscis Monkey is listed as Endangered due to habitat loss and mangrove deforestation. Local initiatives in Tawau include:

• Sabah Wildlife Department  -  Leads the Proboscis Monkey Action Plan 2019 - 2028, supported by Danau Girang Field Centre and Yayasan Sime Darby.
• 1StopBorneo Conservation  -  Active in Tawau, focusing on mangrove protection and community awareness.
• Wildlife Sanctuary Sabah  -  Mangrove restoration and replanting projects.
• Community-based groups  -  Local fishermen and youth groups replant mangroves along Tawau River estuary.

• Champion Swimmers: They are exceptional swimmers and the most aquatic Old World monkey. They use partially webbed hands and feet to cross rivers with ease, often plunging from trees into the water.
• Underwater Explorers: Contrary to the draft's claim, their known ability is closer to diving and swimming effectively, but specific metrics like "20 meters underwater" without surfacing are difficult to verify precisely and can vary. They are highly adept at navigating water.
• The Nose Knows: The exaggerated, pendulous nose of the adult male can grow over 10 cm (nearly 4 inches) long. This prominent feature serves two main purposes:
  • Attracting Mates: Females prefer males with larger noses.
  • Sound Amplifier: The nose acts as a resonating chamber, amplifying their loud honks and calls to communicate effectively across their mangrove and riverine habitats.
• Habitat Harmony: Proboscis monkeys share their environment with other primates, such as the Red Leaf Monkey (Presbytis rubicunda). However, they avoid competition by occupying different ecological niches - Proboscis monkeys prefer river edges and mangroves, while Red Leaf Monkeys typically stick to the forest canopy.
• Diverse Communication: They use a variety of unique vocalizations, including loud honks, coughs, and distinctive splashing sounds when moving through the water, to interact within their social groups.