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)

Habitat

H. spadiceus is 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
    in

Reproduction

Nothing is known about the mating systems of this species.

Reproductive data is known for H. lepidus, which is a closely related species that has previously been considered a subspecies of H. spadiceus. The population structure of H. 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, perdiodicity is irregular and superannual, 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 H. 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 H. spadiceus. (Mull and Liat, 1971)

  • Breeding interval
    Irregular superannual
  • Breeding season
    Can occur at any time of the year
  • Range number of offspring
    1 to 4
  • Average number of offspring
    2
  • Average gestation period
    40 days

Nothing is known about the parental investment of this species

Lifespan/Longevity

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

Behavior

H. spadiceus has 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. H. spadiceus also employs 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

H. spadiceus has 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

Predation

The related species, Hylopetes alboniger, is shot for bushmeat by humans. Since this species shares much of the distribution of H. spadiceus, it is likely that the red-cheeked flying squirrel is 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 H. spadiceus 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
  • Capillaria hepatica, 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 H. spadiceus often occupies and feeds in cultivated forest or crop areas, they may have a negative economic impact. (Murali, et al., 2013; Nowak, 1991)

  • Negative Impacts
  • crop pest

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)

Contributors

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

Glossary

agricultural

living in landscapes dominated by human agriculture.

arboreal

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.

chemical

uses smells or other chemicals to communicate

endothermic

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.

folivore

an animal that mainly eats leaves.

forest

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

frugivore

an animal that mainly eats fruit

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

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).

motile

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.

nocturnal

active during the night

omnivore

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

oriental

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.

sexual

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

solitary

lives alone

tactile

uses touch to communicate

tropical

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

visual

uses sight to communicate

viviparous

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

References

Ahl, A. 1987. Relationship of Vibrissal Length and Habits in the Sciuridae. Journal of Mammalogy, 68: 848-853. Accessed October 17, 2015 at http://www.jstor.org.uml.idm.oclc.org/stable/1381563?origin=crossref&seq=1#page_scan_tab_contents.

Colley, F., W. Mullin. 1971. New Species of Eimeria (Protozoa: Eimeriidae) from Malaysian Squirrels. Journal of Protozoology, 18: 400-402. Accessed November 26, 2015 at http://onlinelibrary.wiley.com/doi/10.1111/j.1550-7408.1971.tb03342.x/abstract.

Duckworth, J., S. Hedges. 2008. "Hylopetes spadiceus (Red-cheeked Flying Squirrel)" (On-line). IUCN Red List of Threatened Species. Accessed September 20, 2015 at http://www.iucnredlist.org/details/10607/0.

Dunn, F., B. Lim, L. Yap. 1968. Endoparasite Patterns in Mammals of the Malayan Rain Forest. Ecology, 49: 1179-1184. Accessed October 13, 2015 at http://www.jstor.org.uml.idm.oclc.org/stable/1934508?origin=crossref&seq=1#page_scan_tab_contents.

Mull, I., L. Liat. 1971. New Locality Records for Some Mammals of West Malaysia. Journal of Mammalogy, 52: 430-437. Accessed October 17, 2015 at http://www.jstor.org.uml.idm.oclc.org/stable/1378686?origin=crossref&seq=1#page_scan_tab_contents.

Mull, I., L. Liat. 1974. Reproductive Frequency in Malaysian Flying Squirrels, Hylopetes and Pteromyscus. Journal of Mammalogy, 55: 393-400. Accessed October 18, 2015 at http://www.jstor.org.uml.idm.oclc.org/stable/1379007?origin=crossref&seq=1#page_scan_tab_contents.

Murali, K., C. Parimal, S. Kuladip, K. Awadhesh. 2013. "Observations on Particolored Flying Squirrel Hylopetes alboniger (Hodgson 1836) in Northeast India" (On-line pdf). Accessed October 13, 2015 at http://www.researchgate.net/profile/Kuladip_Sarma/publication/256078833_Observations_on_Particolored_Flying_Squirrel_Hylopetes_alboniger_(Hodgson_1836)_in_Northeast_India/links/00b495217379fae0d9000000.pdf.

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

Osgood, W. 1934. Zoological Results of the Third De Schauensee Siamese Expidition, Part IV: Mammals. Proceedings of the Academy of Natural Sciences of Philadelphia, 86: 311-315. Accessed October 22, 2015 at http://www.jstor.org.uml.idm.oclc.org/stable/4064151?seq=1#page_scan_tab_contents.

Rasmussen, N., R. Thorington. 2008. Morphological Differentiation among Three Species of Flying Squirrels (Genus Hylopetes) from Southeast Asia. Journal of Mammalogy, 89: 1296-1305. Accessed October 13, 2015 at http://www.jstor.org.uml.idm.oclc.org/stable/25145220.

Song, L., Y. Fa-Hong. 2013. Differentiation in cranial variables among six species of Hylopetes (Sciurinae: Pteromyini). Zoological Research, 34: 109-119. Accessed November 10, 2015 at https://tspace.library.utoronto.ca/bitstream/1807/64906/1/zr13084.pdf.

Thorington, R., K. Darrow, C. Anderson. 2011. Wing Tip Anatomy and Aerodynamics in Flying Squirrels. Journal of Mammalogy, 79: 245-250. Accessed October 13, 2015 at http://www.jstor.org.uml.idm.oclc.org/stable/1382860?origin=crossref&seq=1#page_scan_tab_contents.

Thorington, R., L. Heaney. 1981. Body Proportions and Gliding Adaptations of Flying Squirrels (Petauristinae). Journal of Mammalogy, 62: 104-114. Accessed October 12, 2015 at http://www.jstor.org.uml.idm.oclc.org/stable/1380481?origin=crossref&seq=1#page_scan_tab_contents.

Thorington, R., J. Koprowski, M. Steele, J. Whatton. 2012. Squirrels of the World. Baltimore, Maryland: The John Hopkins University Press.

Wells, K., M. Pfeiffer, M. Lakim, K. Linsenmair. 2004. Use of Arboreal and Terrestrial Space by a Small Mammal Community in a Tropical Rain Forest in Borneo, Malaysia. Journal of Biogeography, 31: 641-652. Accessed October 20, 2015 at http://www.jstor.org.uml.idm.oclc.org/stable/3554715?seq=1#page_scan_tab_contents.

Wilson, D., D. Reeder. 2005. Mammal Species of the World: A Taxonomic and Geographic Reference. Third Edition, Volume 2. Baltimore, Maryland: The John Hopkins University Press.

Yu, F., X. Lian, Z. Li, M. Xie. 2014. A molecular phylogenetic study of Hylopetes (Rodentia: Sciuridae) inferred from mitochondrial cytochrome-b gene. Biologia, 69: 1777-1783. Accessed October 17, 2015 at http://link.springer.com.uml.idm.oclc.org/article/10.2478%2Fs11756-014-0474-5.

van Peenan, J., P. Cunningham, M. Duncan. 1970. A Collection of Mammals from Con Son Island, Vietnam. Journal of Mammalogy, 51: 419-424. Accessed October 18, 2015 at http://www.jstor.org.uml.idm.oclc.org/stable/1378509?origin=crossref&seq=1#page_scan_tab_contents.