Hylopetes spadiceusred-cheeked flying squirrel

Geographic Range

Hylopetes spadiceus has been found throughout Southeast Asia, stretching south from Myanmar to Thailand, Malaysia, Indonesia, and the northern reaches of the island of Borneo. It is also found in south Vietnam, Sumatra, Lao People's Democratic Republic, and Singapore.

It has been noted that the range of H. spadiceus may be greater than reported, but this species shares a similar distribution with other members of the genus, which makes it difficult to discern the boundaries when the species are so morphologically similar. In addition, there have been many inconsistencies in the exact number of species and subspecies reported, and some of these conflicts have not yet been resolved. Thus, it is difficult to definitively outline the distribution of one species when there are differing reports of exactly what populations would be incuded in that species.

The type locality for this species is from Arakan, Burma. (Mull and Liat, 1971; Osgood, 1934; Thorington, et al., 2012; Wilson and Reeder, 2005; Yu, et al., 2014)


Red-cheeked flying squirrels are found in primary forests, secondary forest and scrub, and cultivated areas. This species of squirrel is specialized for an aerial lifestyle of gliding between trees. Individuals make their nests in hollow trees or limbs, or sometimes build nests of twigs and leaves. It is not yet known if trees of any particular species are preferred. (Duckworth and Hedges, 2008; Nowak, 1991; Wells, et al., 2004)

  • Range elevation
    1500 (high) m
    4921.26 (high) ft

Physical Description

Red-cheeked flying squirrels have orange/brown pelage with brighter red/orange cheek and tail coloration. As members of the arrow-tailed flying squirrels, their tails resemble broad, flat arrow heads. The presence of a furred patagium, which is a convergent trait among many mammals, indicates the well developed gliding ability of H. spadiceus. The patagium is a membrane formed by sheets of muscle that extends from the side of the body to the arms and legs. A rod of cartilage extends from the wrist to act as a spreader for the gliding membrane. Wing loading for the species is approximately 50 N/m2; an intermediate loading value within the tribe. As with all flying squirrels, large eyes are indicative of a nocturnal lifestyle. The hind foot is pentadactyl and the fore foot is tetradactyl.

Compared to other species in the genus Hylopetes, H. spadiceus is more gracile, and on average, has a smaller skull than most of the other genus members. Average skull length is 35.58 mm and 34.58 mm for males and females, respectively. Average zygomatic breadth is 21.79 mm and 20.78mm, respectively. Well-developed postorbital processes are present, as is the case for most squirrels. The dental formula for this species is 1/1 0/0 1/1 3/3 for a total of 20 teeth. Molariform teeth are low-crowned and cuspidate. Sexual dimorphism is not pronounced, but males are on average, slightly larger in terms of their body measurements and mass. Mass for the species ranges from 50-80 grams.

There are 3 recognized subspecies of Hylopetes spadiceus, based on their geographic distributions: H. s. spadiceus- found in peninsular Malaysia. H. s. everetti- found in the island of Borneo. H. s. sumatrae- found in Sumatra. (Ahl, 1987; Nowak, 1991; Thorington and Heaney, 1981; Thorington, et al., 2011)

  • Sexual Dimorphism
  • male larger
  • Range mass
    50 to 80 g
    1.76 to 2.82 oz
  • Average length
    HB: 145.75 mm, T: 127.10 mm


Nothing is known about the mating systems of this species.

Reproductive data is known for Hylopetes lepidus, which is a closely related species that has previously been considered a subspecies of Hylopetes spadiceus. The population structure of Hylopetes lepidus is adult biased, with only a per capita estimate of 0.6 young per adult female. Breeding does not appear to coincide with any environmental cues throughout the year and thus varies from year to year. As such, periodicity is irregular and super-annual, and includes intervals of breeding inactivity of up to 17 months. Once reproductive activity begins within a population, it lasts for 6-7 months, and is highly synchronized among individuals.

The gestation period of Hylopetes lepidus is approximately 40 days, and between 1 and 4 young are produced, with an average of 2. Nothing is yet known about the duration of lactation for Hylopetes spadiceus. (Mull and Liat, 1971)

  • Breeding interval
    Breeding is irregular and may be super-annual in periodicity.
  • Breeding season
    Breeding can occur at any time of the year
  • Range number of offspring
    1 to 4
  • Average number of offspring
  • Average gestation period
    40 days

Nothing is known about the parental investment of this species


Nothing is known about the lifespan or longevity of this species.


Red-cheeked flying squirrels have been observed gliding over distances greater than 50 meters between trees, and is even able to ascend up to a meter by altering the angle and position of the patagium. This species appears to be solitary, but no studies have analyzed their behavior in-depth. (Duckworth and Hedges, 2008; van Peenan, et al., 1970)

Home Range

No data is available on home range for this species.

Communication and Perception

Vocalizations have not been documented in this species, as most individuals appear to be relatively silent. There is a strong emphasis on visual perception using large eyes, which coincides with the nocturnal lifestyle of flying squirrels. Red-cheeked flying squirrels also employ tactile perception by use of vibrissae. The ratio of vibrissae length to head length is higher for aerial squirrels than for terrestrial or arboreal squirrels. (Ahl, 1987; Nowak, 1991)

Food Habits

Red-cheeked flying squirrels have been observed primarily feeding on flowers, fruits, and leaves, including those in agricultural areas. For this diet, this species has a loss of canines and enhancement of cusps on cheek teeth (characteristic of members of the Order Rodentia). There have been some instances of red-cheeked flying squirrels also feeding on insects. (Murali, et al., 2013; Nowak, 1991)

  • Animal Foods
  • insects
  • Plant Foods
  • leaves
  • seeds, grains, and nuts
  • fruit
  • flowers


The related species, Hylopetes alboniger, is shot for bushmeat by humans. Since this species is sympatric with red-cheeked flying squirrels, it is likely that they are also killed by humans for meat. There is not much known about other predators of this species. The aerial and arboreal lifestyle of H. spadiceus likely aids in evasion of terrestrial predators. (Murali, et al., 2013; Thorington, et al., 2012; van Peenan, et al., 1970)

Ecosystem Roles

Flowering plants exploit the diet of red-cheeked flying squirrels to aid in seed dispersal to novel locations (biotic vector). Capillaria hepatica (a parasitic nematode) and another unidentified nematode have been found in H. spadiceus, in addition to Eimeria hylopetis, an eimeriid protozoan. (Colley and Mullin, 1971; Dunn, et al., 1968; Nowak, 1991)

  • Ecosystem Impact
  • disperses seeds
Mutualist Species
  • Phylum Anthophyta
Commensal/Parasitic Species
  • nematodes (Capillaria hepatica)
  • nematodes (Eimeria hylopetis)

Economic Importance for Humans: Positive

There are no known positive effects of Hylopetes spadiceus on humans.

Economic Importance for Humans: Negative

Many rodents are considered to be pests by humans. Since red-cheeked flying squirrels often occupy and feed in cultivated forest or crop areas, they may have a negative economic impact. (Murali, et al., 2013; Nowak, 1991)

Conservation Status

Hylopetes spadiceus is not an endangered species, but it is suffering from habitat loss due to deforestation and habitat destruction. There are some protected zones within its distribution that were created in an effort to help prevent any potential threats to the species. (Duckworth and Hedges, 2008)


Riley Fache (author), University of Manitoba, Jane Waterman (editor), University of Manitoba, Tanya Dewey (editor), University of Michigan-Ann Arbor.



living in landscapes dominated by human agriculture.


Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


uses smells or other chemicals to communicate


animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.


an animal that mainly eats leaves.


forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.


an animal that mainly eats fruit


an animal that mainly eats seeds


An animal that eats mainly plants or parts of plants.


offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).


having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.


active during the night


an animal that mainly eats all kinds of things, including plants and animals


found in the oriental region of the world. In other words, India and southeast Asia.

World Map

scrub forest

scrub forests develop in areas that experience dry seasons.


reproduction that includes combining the genetic contribution of two individuals, a male and a female


lives alone


uses touch to communicate


Living on the ground.


the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.


uses sight to communicate


reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

year-round breeding

breeding takes place throughout the year


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Nowak, R. 1991. Walker's Mammals of the World. New York, N.Y.: The John Hopkins University Press.

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