In Southeast Asia, there is an animal with a unique locomotion adaptation. That animal is the Sunda flying lemur (Galeopterus variegatus).
Despite being known as a flying lemur, the animal is not a member of the primate order or a true lemur species. Taxonomically, it belongs to the order Dermoptera and the family Cynocephalidae.
It also does not truly fly through active wing-flapping. Instead, the animal glides from tree to tree within the forest using a specialized membrane on its body.
Morphology of the Inter-Canopy Glider
The Sunda flying lemur is medium-sized, with a head-and-body length of approximately 33 to 42 centimeters. Its tail measures between 17 and 27 centimeters in length.
The body of the Sunda flying lemur is covered in dense fur patterned with gray, brown, or reddish speckles. The coloration mimics the surface of tree bark.
An adult Sunda flying lemur weighs between 0.9 and 2 kilograms. Its body features an expansive skin membrane known as the patagium.
The patagium extends from the neck region, through the spaces between the digits, down to the tip of the tail. When all four limbs are fully extended, the membrane can reach a span of about 70 centimeters.
The thin tissue catches air pressure, allowing the animal to glide for tens of meters. The gliding ability is used to travel from one tree to another.
In addition to the patagium, the lower front jaw of the Sunda flying lemur features a unique row of teeth. The comb-like structure of the lower incisors helps the animal cut tender leaves and groom its fur.
The tips of its digits feature sharp, curved claws. The adaptation functions to climb tree trunks.
Most of the animal's life takes place entirely in the trees (strictly arboreal). Its feet and digits are not structured for walking on the ground, which makes its movement on terrestrial surfaces extremely slow and vulnerable to threats.
Bound to Trees, Vulnerable on the Ground
Its limited mobility on the ground makes the Sunda flying lemur heavily dependent on the forest canopy. The animal conducts most of its foraging activities at night.
During the day, it rests in the fronds of coconut palms or along tree trunks. Its mottled fur provides effective camouflage against tree bark.
When night falls, the Sunda flying lemur climbs tree trunks using its claws to reach the upper canopy. From the elevated position, it glides down toward target trees offering food sources. Its diet primarily consists of young leaves, flower parts, and forest fruits.
When feeding on flowers, pollen can stick to its facial fur and be transferred to other trees. Seeds from consumed fruits are also dispersed across new forest areas through dropped food remnants or excreted waste while moving between trees.
The Sunda Flying Lemur in Its Native Habitat
Populations of Galeopterus variegatus are distributed across the rainforests of Southeast Asia. Its range encompasses Indochina, Thailand, Malaysia, Singapore, Brunei Darussalam, and Indonesia.
In Indonesia, the presence of the animal is documented in Sumatra, Kalimantan, and the western region of Java. The survival of the mammal depends on the availability of lowland forest ecosystems below an elevation of 1,000 meters above sea level.
The animal is also capable of inhabiting secondary environments. It can be found in coconut plantations as well as mangrove vegetation.
The International Union for Conservation of Nature (IUCN) classifies Galeopterus variegatus under the category of Least Concern. The status is assigned because its rate of population decline has not yet met the threshold for a threatened category, although its overall population trend continues to decline.
Lowland deforestation represents the primary threat to the Sunda flying lemur. Land-use changes reduce the availability of trees needed for foraging and shelter.
Additional threats stem from traditional hunting activities by local communities targeting the animal for its fur and meat. In plantation areas, IUCN reports also note suspected foraging competition between the Sunda flying lemur and the plantain squirrel.
In Indonesia, populations of the animal are recorded within protected areas in West Java Province, such as Mount Halimun Salak National Park and the Masigit-Kareumbi Hunting Park.
Reference:
Boeadi, & Steinmetz, R. (2008). Galeopterus variegatus. The IUCN Red List of Threatened Species 2008, e.T41502A10479343. https://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T41502A10479343.en
