The Sunda flying lemur (Galeopterus variegatus), also called the colugo, is one of the stranger mammals in Bako National Park. Despite its common name it is neither a lemur nor capable of true flight — it is the only member of its own mammalian order, Dermoptera, and its closest relatives are primates. A membrane called a patagium stretches from its neck to its fingers, toes, and the tip of its tail. When spread, this creates a living kite that can glide over 100 metres between trees, losing less than 10 metres of altitude per 100 metres of horizontal distance.
Flying lemurs are almost entirely nocturnal and spend the daylight hours clinging motionless to tree trunks, their mottled grey-green fur providing near-perfect camouflage against bark. If you see what looks like a loose flap of bark roughly the size of a cat pressed flat against a large trunk on the Lintang Trail, look more carefully — it may be a colugo. Their crypsis is exceptional, and many visitors walk past them without noticing.
At dusk they become active, launching from high in the canopy and gliding silently to the base of another tree, then climbing back up to glide again. This is their primary mode of locomotion — they are cumbersome on the ground and prefer never to touch it. Their diet consists of soft plant material: young leaves, flowers, and sap. The mother carries her single infant tucked against her chest, the patagium folded around it like a hammock, and continues to glide while carrying the young for the first six months of its life.
Flying lemurs are listed as Least Concern globally but require old-growth forest with tall, widely spaced trees to glide between. Bako's relatively intact forest canopy, particularly around the Lintang and Bukit Gondol trails, provides ideal habitat. They are most often seen at dusk from the elevated sections of the Bukit Gondol summit trail — look for sudden silent movement across gaps in the canopy. On the night walk, the Bornean tarsier and flying lemur are frequently spotted in the same area, though the tarsier stays lower in the vegetation.