Petaurilluspygmy flying squirrels


Petaurillus is a genus commonly known as pygmy flying squirrels, and consists of three identified species. Petaurillus emiliae is the smallest flying squirrel and is only reported to be found in Sarawak, Malaysia. Petaurillus hosei is a small flying squirrel found in Northern Borneo (Malaysia) and looks similar in color and markings to Petaurillus emiliae but is twice the size. Petaurillus kinlochii is also found in Malaysia and is sized in between Petaurillus emiliae and Petaurillus hosei. All three species rely on dense forests for nutrition and shelter but live in areas that are affected by heavy deforestation. (Thorington Jr. and Darrow, 2000; Thorington Jr. and Jackson, 2012; Thorington Jr., et al., 2005; Thorington Jr., et al., 2012; Thorington Jr., et al., 2002)

Geographic Range

Petaurillus individuals are found in the Oriental Region of the world and is endemic to the peninsula and island of Malaysia. Petaurillus kinlochii has only been found near Selangor (peninsular Malaysia) in areas that have recently succumbed to deforestation. Petaurillus hosei is found in Northern Borneo (Malaysia) near Sabah and Sarawak. Petaurillus emiliae is found nearby in the forests of Sarawak, Malaysia. (Thorington Jr., et al., 2012)


Petaurillus live within the tropical region of Malaysia and are highly arboreal. Individuals live within trees where they can reach their main source of nutrition which consists of fruits and seeds. Petaurillus hosei have been found using tree cavities as nest holes for shelter and to care for their young. (Thorington Jr. and Darrow, 2000; Thorington Jr., et al., 2012)

Systematic and Taxonomic History

Petaurillus is within the tribe Pteromyini. 'Ptero' is a Greek word meaning wing and 'myini' means small. Petaurillus hosei is named after zoologist Charles Hose, however no recent literature states the reasoning behind the names of the other two species within the genus. (Duckworth and Francis, 2008; The Editors of Encyclopaedia, 2020)

Physical Description

Physical descriptions are known through observations of only five specimens. Flying squirrels in the genus Petaurillus are known for their small size and feather-like tails. Petaurillus weigh less than 1 kilogram with the smallest species Petaurillus emiliae weighing an average of 27 grams. Flying squirrels are distinguished from other squirrels by a small membrane that extends between their wrists and ankles that extends when gliding. Recorded measurements of the five specimens consist of head to body length of 80-96 mm, tail length 61-94 mm, and ear length 10-16 mm. (Jackson, 2012; Yoon Ling, et al., 2016)


No information is listed in current literature about the reproduction of Petaurillus, however, other species within the family Sciuridae are polygynandrous. Multiple males may mate with multiple females in a single breeding season. (Jackson, 2012; Thorington Jr. and Jackson, 2012)

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • sexual

No information is listed in current literature about the parental investment of Petaurillus, however, other species within the family Sciuridae show that the female will provide care and nutrition for the young until they mature. (Jackson, 2012; Thorington Jr. and Jackson, 2012)


There is limited research on the lifespan of Petaurillus, but one specimen was observed to live 2 years in the wild. However, because these pygmy flying squirrels are endemic to small regions in Malaysia that are undergoing heavy urbanization, the longevity of this genus is threatened. (Thorington Jr. and Jackson, 2012; Thorington Jr., et al., 2012)


Pygmy flying squirrels are arboreal and nocturnal. Although they have a thin membrane that stretches from their wrists to their legs, these are not considered wings and pygmy flying squirrels do not actually fly. Instead, these squirrels glide through the air as they move through the treetops. They nest within trees where they raise young and aggregate with other pygmy flying squirrels for warmth. This genus of squirrels does not hibernate, as they live in a warm climate. (Thorington Jr. and Darrow, 2000; Thorington Jr. and Jackson, 2012; Thorington Jr., et al., 2012)

Communication and Perception

Although Petaurillus are nocturnal, they have not been observed to use echolocation. Instead, these pygmy flying squirrels are similar to tree squirrels in that they use a few distinct vocalization cues, but rely mostly on body language to communicate with each other and with other animals around them. (Thorington, et al., 2006)

Food Habits

No information is reported about the food habits of Petaurillus but other arboreal species tend to be omnivores, eating a diet of seeds, nuts, insects, fungi, and fruit. (Thorington Jr. and Darrow, 2000; Thorington Jr. and Jackson, 2012)


Little is known about the natural predators of Petaurillus but because these species are endemic to specific areas in Malaysia that are experiencing heavy urbanization, humans are a huge threat to these animals. Species within Petaurillus are arboreal and when the forests that home them are removed for human urbanization, they become threatened. (Thorington Jr. and Jackson, 2012)

  • Known Predators
    • Human

Ecosystem Roles

Not enough is known at this time about the ecological role of Petaurillus, however, because the species are arboreal and feed on native fruit and seeds, their role in forest development and seed dispersal is similar to other tree squirrels. (Thorington Jr. and Darrow, 2000)

Economic Importance for Humans: Positive

No information is listed in credible literature about the known positive effects of Petaurillus on humans.

Economic Importance for Humans: Negative

There are no known adverse effects of Petaurillus on humans.

Conservation Status

The conservations status for the species within Petaurillus are listed as "unknown" by the IUCN.

  • IUCN Red List [Link]
    Not Evaluated


Madison Martin (author), Colorado State University, Audrey Bowman (editor), Colorado State University.



uses sound to communicate


young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.


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.

female parental care

parental care is carried out by females


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.

island endemic

animals that live only on an island or set of islands.


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


the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.


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


uses touch to communicate


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


uses sight to communicate


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