FLYING SQUIRRELS OF BORNEO, INDONESIA AND MALAYSIA

FLYING SQUIRRELS IN BORNEO

Among the gliding species found in Borneo are a flying lemur, flying snakes and 14 species of flying squirrel. The largest is the red giant flying squirrel. It can reach length of three feet, including the tail. It is russet red in color and has needle sharp claws that it uses to cling to tree bark. They live in pairs and spends their days in a hole in a tree and usually emerge in the late afternoon.

Flying squirrels found in Borneo look like they are wearing a loose cloak when they are not in flight. When they glide their skin inflates like a parachute enabling the animal to travel more than 100 meters in a single glide. It can steer by moving its long furry tail from side to side like a rudder and land exactly at the spot it wants to.

Describing a pair of giant flying Borneo squirrel, David Attenborough wrote, “For a minute the or two they will circle the trunk and then, suddenly and unexpectedly, one will leap off unfurling as it does a great cloak of skin that stretches on either side from wrist to ankle. Its long bushy tall streams out behind acting, it seems, like a rudder. As one goes, its partner is likely to follow...for maybe 30 or 40 meters towards another trunk. As they near it, they swoop upwards, slowing their glide and enabling them to land, head uppermost, on the trunk, up which they then gallop up...When the owner of it tries to run, the membrane is so big it is something if ab encumbrance. The Asiatic giant, lolloping a long a branch, looks as though it is wearing a voluminous cloak. It is not surprising, therefor, the flying squirrels seldom come out of their hotels during the day when there are eagles and other predators around that could pounce on them. In the evenings, however, they will emerge and in the gathering dusk and put on an unforgettable display of aerobatics as they tease one another from branch to branch and tree to tree.

Black Flying Squirrels

black flying squirrel

Black flying squirrels (Aeromys tephromelas) are also called large black flying squirrel. They are found on the Malayan Peninsula and the islands of Penang, Sumatra, and Borneo. There have also been reports of them in Thailand, but these sightings have not been confirmed and could have been a similar species. The lifespan of similar flying squirrel five to 10 years in the wild and 10 to 20 years in captivity. Black flying squirrels tend to have a slower population turnover than other squirrels because they have small litter sizes and breed infrequently.[Source: Ana Breit, Animal Diversity Web (ADW) /=]

Black flying squirrels inhabit both primary and secondary forests in the lowlands and foothills of mountains in Peninsular Malaysia and Borneo. They are uncommon in deep forests and prefer mature forests or clearings with few large trees tend to avoid fruit and rubber plantations. Large trees provide them with potential nesting cavities. They have been found near human settlements and thus are believed to be relatively adaptable. Black flying squirrels have been categorized as omnivores (eat a variety of things, including plants and animals). Animal foods include insects. Among the plant foods they eat are leaves, seeds, grains, nuts and fruit.

On the International Union for Conservation of Nature (IUCN) Red List black flying squirrels are listed as Data Deficient. They are rare to begin with and are elsusive so it is hard to figure out how many there are. Their main threat is habitat loss. Lowland forests, which these animals favor, tend to be the first forests logged and developed.

Black Flying Squirrel Characteristics and Behavior

Black flying squirrels range in weight from 1.1 to 1.25 kilograms (2.4 to 2.75 pounds) and have a head and body length that ranges from 25.5 to 42.6 centimeters (10 to 16.8 inches). Their tail is between 28 and 52.7 centimeters (11 and 20.7 inches) long. Their gliding surface area, excluding the head and tail, is about 1,600 square centimeters Sexual Dimorphism (differences between males and females) is for the most part not present: Both sexes are roughly equal in size and look similar. Females tend to be slightly larger than males but not significantly so. [Source: Ana Breit, Animal Diversity Web (ADW) /=]

range of the black flying squirrel

There are two subspecies of black flying squirrel distinguished primarily by their fur color: 1) A.t. tephromelas is mainly black and 2) A. t. phaeomelas is orange-red. With A.t. tephromelas, the fur on the back, head and cheeks is dark gray to black with some slight, pale flecking on the back. With both species their undersides are paler than their backs.

Black flying squirrels are arboreal (live mainly in trees), have the ability to glide, nocturnal (active at night), motile (move around as opposed to being stationary) and sedentary (remain in the same area). They spend the night moving about upper canopy of the forest foraging for food and spend the day resting and sleeping in their tree cavity nests. They sense using vision, touch and chemicals usually detected with smell and communicate with vision, sound and chemicals and employ pheromones (chemicals released into air or water that are detected by and responded to by other animals of the same species) and scent marks produced by special glands and placed so others can smell and taste them.

Little is known about black flying squirrel mating habits. Female black flying squirrels always generally produce a litter of just one young. The age in which they are weaned ranges from three to four months and the average time to independence is one year. Parental care is provided by females.

Javanese Flying Squirrels

Javanese flying squirrels (lomys horsfieldii) are found in patches in peninsular Malaysia, Sumatra, Java, and Borneo. There have been sightings of individuals in Singapore, Tioman, and Penang. They are fairly adaptable and have been found in a variety of habitats: various forest environments, degraded land, scrub bush and durian plantations. They nest in hollow trees and have been spotted at elevations up to 1000 meters (3281 feet). [Source: Shannon Cruz, Animal Diversity Web (ADW) /=]

Javanese flying squirrel range

Javanese flying squirrels are not endangered. The International Union for Conservation of Nature (IUCN) Red List classifies them as a species of “Least Concern”. In CITES (Convention on International Trade in Endangered Species of Wild) they have no special status. There is no information about the diet, predators and lifespan of Javanese flying squirrels. Similar flying squirrels eat fruits, nuts, and shoots and have lived in captivity up to 13.5 years. They may be preyed upon by civets, linsang and binturong. Their biggest threats are pressures from human settlemenst and deforestation.

Javanese flying squirrels are mostly orange-brown to brown-gray in color, with a tail that is a slightly brighter shade on the ventral surface and sides. Body length averages 18.2 centimeters (7.2 inches). The tail is as long as, or slightly longer than the body. Like other flying squirrels, Javanese flying squirrels have a patagium (thin membrane of skin between the forelimbs and hindlimbs used for gliding). The patagium is slightly darker in color than the rest of the body. Javanese flying squirrels also have relatively large eyes and ears and long claws for gripping the trees that they live in.

Javanese flying squirrels can be distinguished from other flying squirrels by their orange tinge and lighter underbelly, and the absence, or near absence of hair on the upper surface of the ear lobe. The very similar in appearance to Whiskered flying squirrel (Petinomys genibarbis), which can be distinguished from Javanese flying squirrels by the presence of a five- millimeter wart on the cheek, sprouting long black whiskers.

Javanese Flying Squirrel Behavior and Reproduction

Javanese flying squirrels are arboreal (live mainly in trees), scansorial (able to or good at climbing), have the ability to glide, nocturnal (active at night), motile (move around as opposed to being stationary), sedentary (remain in the same area) and probably solitary. Like other flying squirrels, they are probably able to glide long distances between trees and use their long claws for grip. [Source: Shannon Cruz, Animal Diversity Web (ADW) /=]

Javanese flying squirrels sense and communicate with vision, touch, sound and chemicals usually detected by smelling. They have large eyes and ears relative to their body size and thus it has been deducted they probably have a good sense hearing and strong night vision. As with similar species, they likely use visual, auditory, and chemical cues in communication.

Javanese flying squirrels are not well studied and their mating system is as yet unknown. Related species have one or two young per litter. The fairly uniform of the tropical climate they live in may mean they give birth year round.

Red-Cheeked Flying Squirrels and Temminck's Flying Squirrels

Javanese flying squirrel

Red-cheeked flying squirrels (Hylopetes spadiceus) are found in large patch throughout Southeast Asia — in Myanmar, Thailand, Malaysia, Sumatra, northern Borneo, southern Vietnam, Laos, and Singapore. They live in primary forests, secondary forest and scrub, and cultivated areas. They are adept gliders like other flying squirrels and make their nests in hollow trees or limbs, sometimes with twigs and leaves. They have been seen at elevations of up to 1500 meters (4920 feet). [Source: Riley Fache, Animal Diversity Web (ADW) /=]

Red-cheeked flying squirrels are primarily herbivores (primarily eat plants or plants parts) but are also recognized as folivores (eat mainly leaves), frugivores (eat mainly fruits), granivores (eat seeds and grain) and omnivores (eat a variety of things, including plants and animals). They have been observed feeding mainly on flowers, fruits, and leaves. Among the other foods they eat are seeds, grains, nuts and insects. Eating adaption of this species include the loss of canines and enhancement of cusps on cheek teeth, which is characteristic of most rodents. There are no known positive effects of Red-cheeked flying squirrels on humans. /=

Temminck’s flying squirrels (Petinomys setosus) live throughout much of Southeast Asia — in northwestern and southern Thailand, northern and eastern Myanmar, Sumatra, the northern third of Borneo, southern peninsular Malaysia, and Laos. They are relatively adaptable and survive in a variety of habitats including wet tropical rainforests and dry deciduous and monsoonal forests. They prefer primary forests but have also been observed in partially cut forests and areas in around fruit and rubber plantations.[Source: Ward Chapman; Ashley Contreras; Kathryn DeWilde; Tyler Mohrmann; Dana Sheets-Nichols, Animal Diversity Web (ADW) /=]

Temminck’s flying squirrels are primarily, frugivores (eat mainly fruits) but are also regarded as herbivores (primarily eat plants or plants parts) and granivores (eats seeds and grain). Among the plant foods they eat are seeds, grains, nuts and fruit. On the International Union for Conservation of Nature (IUCN) Red List Temminck’s flying squirrels are listed as Vulnerable. In CITES (Convention on International Trade in Endangered Species of Wild) they have no special status. Their average lifespan in the wild is estimated to be 3.3 years.

Smoky Flying Squirrels

Smoky flying squirrels (Pteromyscus pulverulentus) are found throughout the Malay Peninsula, Sumatra, and northern Borneo (Sabah and Sarawak). They primarily live in lowland primary forests at elevations up to 1000 meters (3281 feet). Black flying squirrel (Aeromys tephromelas) are a similar species except they are larger and have a rounded, fluffy tail, and greyish, fluffy hair on its underparts [Source: Rudolf Haslauer, Animal Diversity Web (ADW) /=]

Smoky flying squirrel

Smoky flying squirrels are listed as Endangered on the International Union for Conservation of Nature (IUCN) Red List. In CITES (Convention on International Trade in Endangered Species of Wild) they have no special status. They are herbivores (primarily eat plants or plants parts), and are also classified as folivores (eat mainly leaves). Among the plant foods they eat are leaves, fruit, buds, blossoms and young shoots. Scientists have warned that human exploitation of the primary forest habitat of these flying squirrel could seriously threaten this unique genus, resulting in their disappearance from Thailand and Malaysia. /=\

Smoky flying squirrels range in weight from 134 to 252 grams (4.7 to 8.9 ounces) have a head and body length that ranges from 22 to 29 centimeters (8.6 to 11.4 inches). Their tail is 18 to 23 centimeters (seven to nine inches) long. Their upper parts are dark brown to blackish, with grey and buffy or whitish bands that give the fur a frosted appearance. The underparts are buffy white, the feet are light brown, and the cheeks are grey. The tail has longer hairs on sides than on the top or bottom, giving it a flattened appearance profile. It is greyish brown with blackish hairs at the tip. /=\

Smoky Flying Squirrels are nocturnal (active at night), motile (move around as opposed to being stationary) and solitary. They sense using touch and chemicals usually detected with smell.. In Sabah they spend their days resting in tree holes three to four meters above the ground. Smoky flying squirrels in Malaysia breed and give birth in all months of the year. The litter size is one to two, with an average of 1.3. Young are born relatively underdeveloped and are unable to feed or care for themselves or move independently for a period of time after birth. /=\

Vordermann's Flying Squirrels

Vordermann's flying squirrels (Petinomys vordermanni) are found scattered here and there in peninsular Malaysia, Myanmar, Borneo, Sumatra and the Belitung and Riau Islands in eastern Sumatra. They are found mostly in forests and prefer tropical, moist, lowland areas near wetlands but also live in second-growth forests, primary forests and dry forests. [Source: Alison O'Dell, Animal Diversity Web (ADW) /=]

Vordermann's flying squirrels are quite small. They range in weight from 18 to 38 grams (0.6 to 1.3 ounces), with an average weight of 36.9 grams (1.30 ounces). Their average length is 17 centimeters (6.57 inches). They have orange cheeks, black fur around their eyes, tufts of whiskers beneath both ears and tails that are flattened on the bottom and bushy on top, which helps control their flight when gliding. Sexual Dimorphism (differences between males and females) is present: Females are larger than males. Males and females have different shapes.

Vordermann's flying squirrel

Vordermann's flying squirrels are omnivores (eat a variety of things, including plants and animals). Animal foods include insects. Among the plant foods they eat are leaves, roots, tubers wood, bark, stems, seeds, grains, nuts, fruit nectar and pollen flowers. They also eat fungus and store food so they do not have to forage during the season in which they are feeding their young. Vordermann's flying squirrels are listed on the International Union for Conservation of Nature (IUCN) Red List as vulnerable. On the US Federal List, CITES and the State of Michigan list, they have no special status. Their main threat is habitat loss.

Vordermann's flying squirrels are arboreal (live mainly in trees), scansorial (able to or good at climbing), have the ability to glide, saltatorial (adapted to leaping), nocturnal (active at night), crepuscular (active at dawn and dusk), motile (move around as opposed to being stationary), sedentary (remain in the same area), have daily torpor (a period of reduced activity, sometimes accompanied by a reduction in the metabolic rate, especially among animals with highmetabolic rates) and social (associates with others of its species; forms social groups). They live in nest holes around six meters above ground, forage in trees, sense using vision, touch, sound and chemicals usually detected with smell and communicate with sound and scent marks. Vordermann's flying squirrels have been recorded gliding more than 90 meters. The taller the trees they leap off of the longer the distances they can glide.

Vordermann's flying squirrels are monogamous (have one mate at a time) are cooperative breeders (helpers provide assistance in raising young that are not their own). They breed once a year, from February to March, with the average number of offspring being two. The birth weights of newborns are around 18 grams. Young stay with their mothers for about five weeks and then leave the nest as independent individuals and hunt and forage for their own food. On average males and females reach sexual or reproductive maturity at 2.5 months.

Pygmy Flying Squirrels

range of the three pygmy flying squirrels

Pygmy flying squirrel is the common name for species in the genus Petaurillus, which has of three identified species: 1)Lesser pygmy flying squirrels (Petaurillus emiliae), the smallest flying squirrel and endemic to Sarawak, Malaysia; 2) Hose's pygmy flying squirrels (Petaurillus hosei), found in Northern Borneo and looks similar ro Lesser pygmy flying squirrels except they are about twice the size; and 3) Selangor pygmy flying squirrel (Petaurillus kinlochii), found only in the State of Selangor in peninsular and is sized in between the other two pygmy flying squirrel specs. All three species rely on dense forests for food and shelter but live in areas that have been affected by deforestation. [Source: Madison Martin, Animal Diversity Web (ADW) /=]

Physical descriptions of pygmy flying squirrel are known from observations of only five specimens. Based on these specimens it has been ascertained that members of the genus Petaurillus are very small in size and have feather-like tails. Lesser pygmy flying squirrels weigh an average of 27 grams. The five specimens had a head to body length of 8 to 9.6 centimeters (3.1 to 3.8 inches), a tail length of 6.1 to 9.4 centimeters (2.4 to 3.7 inches) and ear an length one to 1.6 centimeters (0.4 to 0.6 inches).

No information has been reported about the food habits of pygmy flying squirrel has been reported but based on other flying squirrel species it can be deduced that they are either omnivores (eat a variety of things, including plants and animals), eating a diet of seeds, nuts, insects, fungi, insects and fruit or herbivores (primarily eat plants or plants parts).

Pygmy flying squirrels are arboreal (live mainly in trees), have the ability to glide, nocturnal (active at night) and motile (move around as opposed to being stationary). They do not hibernate, as they live in a warm climate and glide from tree to tree using a patagium (membrane between the forelimbs and hindlimbs used for gliding). They nest in trees and raise their young there.

Hose's Pygmy Flying Squirrels

Hose's pygmy flying squirrel

Hose’s Pygmy flying squirrels (Petaurillus hosei) are endemic to the eastern coast of Sarawak, on the northwestern side of Malaysiam Borneo. They have only been found in lowland tropical rainforests and are reported to use tree cavities as nest holes. No information is available on the diet of Hose’s pygmy flying squirrels but is believed that they seeds, fruits, and fungi and may also take insects, bird eggs and nestlings, and other small animals as they find them. [Source: Tanya Dewey, Animal Diversity Web (ADW) /=]

On the International Union for Conservation of Nature (IUCN) Red List Hose’s Pygmy flying squirrels are listed as Data Deficient. In CITES (Convention on International Trade in Endangered Species of Wild) they have no special status. It presumed they are affected by human distrances. Natural predators are also unknown but may include mammals like clouded leopards, raptors such as owls and arboreal snakes. /=\

Hose’s Pygmy flying squirrel range in weight from 68 to 89 grams (2.40 to 3.14 ounces) and have a head and body length that ranges from 62 to 98 millimeters (2.44 to 3.86 inches). They have large eyes and ears relative to their body szie and have similar to that of other flying squirrels, with a flat hairy tail anda patagium (membrane between the forelimbs and hindlimbs used for gliding). A cartilaginous extension of the wrist bones assists in spreading the patagia. Hose's pygmy flying squirrels have dark dorsal fur and white ventral fur. They have a white spot behind each ear and pale or buffy colored cheeks. The tail is brown with a white tip. Like all flying squirrels they have five digits on their hind limbs and four digits on their forelimbs, each digit has a long claw at the end, which assists in climbing trees.

Red Giant Flying Squirrel

Red giant flying squirrels (Petaurista petaurista) are also known as common giant flying squirrels and giant flying squirrels. Among the largest tree-dwelling squirrels, they range across South Asia, Southeast Asia, Indonesia and China from the eastern border regions of Afghanistan to Java, and from Kashmir, Taiwan, and southern China to Sri Lanka. Its greatest numbers are found in the forest regions of Pakistan. [Source: Sarah Newlin and James Bradshaw, Animal Diversity Web (ADW) /=]

The diet of red giant flying squirrels consists primarily of pine cones, tree buds, leaves, young branches, and, when in season, various fruits and nuts. In captivity, they eat raisins and nuts and refuse shrubs and other leafy substances. Red giant flying squirrels make their nests in the tree cavities of densely forested areas in forests. Their average lifespan in captivity is 16 years. The two main predators of red giant flying squirrels are the charsa marten and the bengal cat, which are able to surprise the squirrel while it sleeps.

Within their geographic range red giant flying squirrels are quite common.The International Union for Conservation of Nature (IUCN) Red List classifies them as a species of “Least Concern”. However, the cutting and burning of forest regions have significantly reduced the size of their habitats. They are sometimes hunted.

Spotted Giant Flying Squirrels

Spotted giant flying squirrels (Petaurista elegans) are also known as lesser giant flying squirrels. Their range extends from Nepal in the west into Southeast Asia and the Malay Peninsula, as far east as Vietnam. Their range in the south includes the islands of Sumatra, Java and Borneo, as well as a few smaller surrounding islands. The lifespan of spotted giant flying squirrels is not known, but members of a related species, red giant flying squirrels, have lived up to 16 years in captivity. [Source: Eva Ryckman, Animal Diversity Web (ADW) /=]

Spotted giant flying squirrels are found in temperate and tropical forests. They are usually encountered in trees 15-20 meters above ground and are more common at higher altitudes — 3,000 to 4,000 meters (9,842 to 13,124 feet). The most often observed at lower elevations in the spring, possibly because there is more food there and less at higher altitudes during that time of year.

Giant flying squirrels were once fairly abundant within their range and they are still are not considered endangered. The International Union for Conservation of Nature (IUCN) Red List classifies them as a species of “Least Concern”. In CITES (Convention on International Trade in Endangered Species of Wild) they have no special status. However, human degradation of their habitat, especially of tall trees necessary for nesting sites, and hunting pressures have had a negative impact on their numbers and breeding success. Likely natural predator include owls and civets.

Image Sources: Wikimedia Commons

Text Sources: Animal Diversity Web animaldiversity.org ; National Geographic, Live Science, Natural History magazine, David Attenborough books, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Discover magazine, The New Yorker, Time, Reuters, Associated Press, AFP, Lonely Planet Guides, Wikipedia, The Guardian, Top Secret Animal Attack Files website and various books and other publications.

Last updated January 2025