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Flying squirrel
Flying squirrel
Flying squirrel
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This article is about the member of the animal kingdom. For other uses, see Flying squirrel (disambiguation).

Flying squirrel
Temporal range: Early Oligocene – Recent
Northern flying squirrel
(Glaucomys sabrinus)
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Sciuridae
Subfamily: Sciurinae
Tribe: Pteromyini
Brandt, 1855
Genera

Aeretes
Aeromys
Belomys
Biswamoyopterus
Eoglaucomys
Eupetaurus
Glaucomys
Hylopetes
Iomys
Petaurillus
Petaurista
Petinomys
Priapomys
Pteromys
Pteromyscus
Trogopterus

Flying squirrels (scientifically known as Pteromyini or Petauristini) are a tribe of 50 species of squirrels in the family Sciuridae. Despite their name, they are not in fact capable of full flight in the same way as birds or bats, but they are able to glide from one tree to another with the aid of a patagium, a furred skin membrane that stretches from wrist to ankle. Their long tails also provide stability as they glide.[1] Anatomically they are very similar to other squirrels with a number of adaptations to suit their lifestyle; their limb bones are longer and their hand bones, foot bones, and distal vertebrae are shorter. Flying squirrels are able to steer and exert control over their glide path with their limbs and tail.

Molecular studies have shown that flying squirrels are monophyletic (having a common ancestor with no non-flying descendants) and originated some 18–20 million years ago. The genus Paracitellus is the earliest lineage to the flying squirrel dating back to the late Oligocene era.[1] Most are nocturnal and omnivorous, eating fruit, seeds, buds, flowers, insects, gastropods, spiders, fungi, bird's eggs, tree sap and young birds. The young are born in a nest and are at first naked and helpless. They are cared for by their mother and by five weeks are able to practice gliding skills so that by ten weeks they are ready to leave the nest.

Some captive-bred southern flying squirrels have become domesticated as small household pets, a type of "pocket pet".[2]

Description

[edit]
A northern flying squirrel (Glaucomys sabrinus) gliding
Southern flying squirrel (Glaucomys volans) skeleton at the NMNH. The styliform cartilage attached to the wrist supports the wing membrane.[3]

Flying squirrels are not capable of flight like birds or bats; instead, they glide between trees. They are capable of obtaining lift within the course of these flights, with flights recorded to 90 metres (300 ft).[4][5] The direction and speed of the animal in midair are varied by changing the positions of its limbs, largely controlled by small cartilaginous wrist bones. There is a cartilage projection from the wrist that the squirrel holds upwards during a glide.[6] This specialized cartilage is only present in flying squirrels and not other gliding mammals.[3] Possible origins for the styliform cartilage have been explored, and the data suggests that it is most likely homologous to the carpal structures that can be found in other squirrels.[3] This cartilage along with the manus forms a wing tip to be used during gliding. After being extended, the wing tip may adjust to various angles, controlling aerodynamic movements.[7][8] The wrist also changes the tautness of the patagium, a furry parachute-like membrane that stretches from wrist to ankle.[8] It has a fluffy tail that stabilizes in flight. The tail acts as an adjunct airfoil, working as an air brake before landing on a tree trunk.[9]

Similar gliding animals

[edit]

The colugos, Petauridae, and Anomaluridae are gliding mammals which are similar to flying squirrels through convergent evolution, although are not particularly close in relation. Like the flying squirrel, they are scansorial mammals that use their patagium to glide, unpowered, to move quickly through their environment.

Evolutionary history

[edit]

Prior to the 21st century, the evolutionary history of the flying squirrel was frequently debated.[10] This debate was clarified greatly as a result of two molecular studies.[11][12] These studies found support that flying squirrels originated 18–20 million years ago, are monophyletic, and have a sister relationship with tree squirrels. Due to their close ancestry, the morphological differences between flying squirrels and tree squirrels reveal insight into the formation of the gliding mechanism. Compared to squirrels of similar size, flying squirrels, northern and southern flying squirrels show lengthening in bones of the lumbar vertebrae and forearm, whereas bones of the feet, hands, and distal vertebrae are reduced in length. Such differences in body proportions reveal the flying squirrels' adaptation to minimize wing loading and to increase maneuverability while gliding. The consequence for these differences is that unlike regular squirrels, flying squirrels are not well adapted for quadrupedal locomotion and therefore must rely more heavily on their gliding abilities.[13]

Several hypotheses have attempted to explain the evolution of gliding in flying squirrels.[14] One possible explanation is related to energy efficiency and foraging.[15][6] Gliding is an energetically efficient way to progress from one tree to another while foraging, as opposed to climbing down trees and maneuvering on the ground floor or executing dangerous leaps in the air.[15] By gliding at high speeds, flying squirrels can rummage through a greater area of forest more quickly than tree squirrels. Flying squirrels can glide long distances by increasing their aerial speed and increasing their lift.[6]

Other hypotheses state that the mechanism evolved to avoid nearby predators and prevent injuries. If a dangerous situation arises on a specific tree, flying squirrels can glide to another, and thereby typically escape the previous danger.[6][16] Furthermore, take-off and landing procedures during leaps, implemented for safety purposes, may explain the gliding mechanism. While leaps at high speeds are important to escape danger, the high-force impact of landing on a new tree could be detrimental to a squirrel's health.[6] Yet the gliding mechanism of flying squirrels involves structures and techniques during flight that allow for great stability and control. If a leap is miscalculated, a flying squirrel may easily steer back onto the original course by using its gliding ability.[6] A flying squirrel also creates a large glide angle when approaching its target tree, decreasing its velocity due to an increase in air resistance and allowing all four limbs to absorb the impact of the target.[6][17]

Fluorescence

[edit]

In 2019 it was observed, by chance, that a flying squirrel fluoresced pink under UV light. Subsequent research by biologists at Northland College in Northern Wisconsin found that this is true for all three species of North American flying squirrels. At this time it is unknown what purpose this serves. Non-flying squirrels do not fluoresce under UV light.[18]

Taxonomy

[edit]

Recent species

[edit]

New World flying squirrels belong to the genus Glaucomys (Greek for gleaming mouse). Old World flying squirrels belong to the genus Pteromys (Greek for winged mouse).

The three species of the genus Glaucomys (Glaucomys sabrinus, Glaucomys volans and Glaucomys oregonensis) are native to North America and Central America; many other taxa are found throughout Asia as well, with the range of the Siberian Flying Squirrel (Pteromys volans) reaching into parts of northeast Europe (Russia, Finland and Estonia).

Thorington and Hoffman (2005) recognize 15 genera of flying squirrels in two subtribes.

Tribe Pteromyini – flying squirrels

The Mechuka, Mishmi Hills, and Mebo giant flying squirrels were discovered in the northeastern state of India of Arunachal Pradesh in the late 2000s.[20][21][22] Their holotypes are preserved in the collection of the Zoological Survey of India, Kolkata, India.

Fossil species

[edit]

Flying squirrels have a well-documented fossil record from the Oligocene onwards. Some fossil genera go far back as the Eocene, and given that the flying squirrels are thought to have diverged later, these are likely misidentifications.[23]

Life cycles

[edit]
A southern flying squirrel (Glaucomys volans) gliding

The life expectancy of flying squirrels in the wild is about six years, and flying squirrels can live up to fifteen years in zoos. The mortality rate in young flying squirrels is high because of predators and diseases. Predators of flying squirrels include tree snakes, raccoons, owls, martens, fishers, coyotes, bobcats, and feral cats.[4] In the Pacific Northwest of North America, the northern spotted owl (Strix occidentalis) is a common predator of flying squirrels.

Flying squirrels are usually nocturnal,[25] since they are not adept at escaping birds of prey that hunt during the daytime.[4] They eat according to their environment; they are omnivorous, and will eat whatever food they can find. The North American southern flying squirrel eats seeds, insects, gastropods (slugs and snails), spiders, shrubs, flowers, fungi, and tree sap.[citation needed]

Reproduction

[edit]

The mating season for flying squirrels is during February and March. When the infants are born, the female squirrels live with them in maternal nest sites. The mothers nurture and protect them until they leave the nest. The males do not participate in nurturing their offspring.[26]

At birth, flying squirrels are mostly hairless, apart from their whiskers, and most of their senses are not present. Their internal organs are visible through the skin, and their sex can be signified. By week five, they are almost fully developed. At that point, they can respond to their environment and start to develop a mind of their own. Through the upcoming weeks of their lives, they practice leaping and gliding. After two and a half months, their gliding skills are perfected, they are ready to leave the nest, and they are capable of independent survival.[27]

Diet

[edit]

Flying squirrels can easily forage for food in the night, given their highly developed sense of smell. They harvest fruits, nuts, fungi, and birds' eggs.[4][28][5] Many gliders have specialized diets and there is evidence to believe that gliders may be able to take advantage of scattered protein deficient food.[29] Additionally, gliding is a quick form of locomotion and by reducing travel time between patches, they can increase the amount of foraging time.[29]

See also

[edit]

References

[edit]

Further reading

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Flying squirrel

View on Grokipedia
from Grokipedia
Flying squirrels, scientifically classified in the tribe Pteromyini within the family Sciuridae, comprise approximately 57 species of gliding rodents distributed across 15 genera, making them the most diverse lineage of gliding mammals. These small to medium-sized squirrels, ranging in body mass from 13.5 g in pygmy species to over 2,700 g in giants like those in the genus Petaurista, are distinguished by their patagium—a furred, parachute-like membrane of skin extending from the wrists to the ankles, and sometimes including a tail membrane, which allows them to glide distances of up to 150 meters or more between trees with remarkable control and agility. Some species, particularly in North America, exhibit biofluorescence, glowing pink under ultraviolet light. Unlike true flight, this gliding adaptation enables efficient arboreal locomotion, sharp turns, and soft landings, supported by their large eyes adapted for nocturnal vision and a slender, furry body with a bushy tail for stabilization. Primarily nocturnal and strictly arboreal, flying squirrels inhabit a wide array of ecosystems, from tropical lowlands and subtropical broadleaf woods to temperate, boreal coniferous forests and even high-elevation habitats above the in the , spanning , , and . Their global distribution reflects an origin with a single colonization event into the New World, where North American species like the northern (Glaucomys sabrinus) and southern (Glaucomys volans) flying squirrels occupy coniferous, , or mixed woodlands, often preferring mature forests with dense canopies for nesting in tree cavities or dreys. In , where the majority of species occur, they thrive in moist temperate and pine-dominated forests at elevations from 100 to 4,500 m, though poses significant threats to many populations. These squirrels play key ecological roles as seed dispersers, mycorrhizal partners through their consumption of fungi, and prey for predators like and martens. Their diet is predominantly herbivorous and mycophagous, consisting of nuts, seeds, fruits, leaves, buds, bark, flowers, and hypogeous fungi (truffles), with occasional , bird eggs, or supplementing the intake, varying by and season—northern species, for instance, rely heavily on lichens and fungi in winter. Reproduction typically occurs in hollows or nests, with most producing one or two litters per year of 1–6 altricial young after a period varying by , typically 37–46 days, though breeding timing aligns with resource availability, such as rainy seasons in tropical regions or spring in temperate zones. Socially, they often form winter aggregations in shared dens for , exhibiting behaviors like vocalizations and scent marking, but many face conservation challenges from , , and , with several listed as vulnerable or endangered.

Physical characteristics

Body structure and gliding adaptations

Flying squirrels are distinguished by their patagium, a fur-covered that extends from the wrists to the ankles, and sometimes including a , enabling controlled aerial descent between trees. This is supported by a styliform , a specialized cartilaginous extension originating from the at the wrist, which projects outward to tension and shape the during . The 's edges are fringed with dense fur, which reduces and enhances aerodynamic stability by minimizing . Limb modifications further adapt flying squirrels for , including elongated forelimbs relative to non-gliding squirrels, which increase the span of the for greater lift. At the wrists, cartilaginous processes, including the styliform element, allow precise control of camber through muscle action, such as contraction of the palmaris longus. The hindlimbs feature similar extensions at the ankles, contributing to the overall support. In contrast to non-gliding squirrels, which lack these extensions and have shorter, more robust limbs suited for terrestrial , flying squirrels exhibit slender, elongated bones that prioritize aerial efficiency over ground propulsion. Their is notably flattened and bushy, functioning as an aerodynamic rudder to steer and stabilize during glides, a trait absent or less pronounced in non-volant relatives. The skull of flying squirrels shows adaptations for their nocturnal, arboreal , including enlarged orbits that accommodate large eyes for enhanced low-light vision. These eye sockets are proportionally larger than in diurnal non-gliding squirrels, reflecting with other night-active mammals to maximize photoreceptor density. Dentally, they retain the characteristic Sciuridae formula with prominent, chisel-like incisors for gnawing hard arboreal foods like nuts and bark, but without unique modifications distinguishing them from non-gliding squirrels beyond overall cranial elongation for lightweight construction.

Size, appearance, and variations

Flying squirrels exhibit a wide range of body sizes across their approximately 56 species, with head-body lengths varying from as small as 7-10 cm in pygmy flying squirrels (Petaurillus spp.) to over 50 cm in giant flying squirrels (Petaurista spp.). Weights correspondingly range from about 20-25 g in the pygmy species to 1.5-3 kg in the largest giants, reflecting adaptations to diverse ecological niches within the tribe Pteromyini. Their appearance is characterized by soft, dense fur that covers the body, providing insulation and a sleek profile enhanced by the , the gliding membrane spanning from wrist to ankle. Coloration typically features muted tones on the dorsum, such as grays, browns, or blacks, contrasted with paler white or cream underparts, though patterns can include subtle striping or spotting in certain taxa. is generally limited, with females often slightly larger than males in body mass and size in several , potentially linked to reproductive demands, but sexes are otherwise similar in pelage and form. The tail is a prominent feature, broad and flattened with bushy fur that gives it a feather-like appearance, aiding in overall aesthetics and balance; its length varies from 70% to 120% of head-body length, being relatively shorter in smaller species like Glaucomys (70-80%) and longer in larger ones. Regional variations in appearance are notable between North American and Asian species. North American flying squirrels (Glaucomys spp.) display subtle, camouflaging grays and browns with minimal markings, suited to temperate forest understories. In contrast, many Asian species exhibit bolder colorations, such as the mahogany-red dorsum and pale underparts of the red giant flying squirrel (Petaurista petaurista), or dark rufous with black accents in other Petaurista taxa, reflecting greater diversity in tropical environments.

Bioluminescence and fluorescence

In 2019, researchers discovered that the fur of in the genus Glaucomys exhibits vivid (UV) , emitting a bright pinkish glow when exposed to UV light. This phenomenon was observed across all 108 examined museum specimens from both recognized —the (Glaucomys sabrinus) and the (Glaucomys volans)—spanning regions from to , and consistent in males, females, and across historical collections dating back to the . The is most pronounced on the ventral (belly) side of the body and appears as a passive response to UV excitation, with no evidence of , which involves self-generated light through biochemical reactions. The chemical basis for this fluorescence lies in the presence of porphyrin compounds accumulated in the fur. These organic molecules, known for their role in various biological pigments, absorb UV light and re-emit it as visible pink light; analyses confirm porphyrin accumulation specifically in the skin appendages, including fur, of these squirrels. While the exact origin of these fluorophores remains under investigation—potentially linked to dietary intake or genetic factors—similar porphyrins have been detected in other mammals, though at levels insufficient to produce noticeable fluorescence. Subsequent mass spectrometry studies on fur extracts have identified multiple potential contributors, but porphyrins stand out as the primary agents in Glaucomys. Potential adaptive functions of this may enhance survival in the squirrels' nocturnal lifestyle within dimly lit canopies, where UV from stars and the could activate the glow. Hypotheses include intraspecific communication, such as signaling during or social interactions among conspecifics; UV to blend with fluorescent elements against UV-sensitive predators; or aposematic signaling to deter threats. These roles are speculative but align with the squirrels' low-light activity patterns, potentially making the trait more visible to conspecifics than to diurnal observers. Post-2019 research has confirmed the absence of this in flying squirrels across genera like and Pteromys, with no pink UV emission reported in examined Asian and European specimens. Ongoing genomic studies aim to identify genes regulating production and accumulation in Glaucomys , comparing them to non-fluorescent relatives to elucidate the trait's evolutionary origins.

Taxonomy and phylogeny

Classification and genera

Flying squirrels are classified within the tribe Pteromyini, part of the subfamily in the family Sciuridae, which encompasses all . This tribe diverged from other squirrel lineages, particularly the tree squirrels of tribe , approximately 30–40 million years ago during the late Eocene to epochs, based on analyses of mitochondrial and nuclear DNA sequences. The Pteromyini comprise approximately 56 extant species distributed across 15 genera, reflecting a diverse array of gliding adaptations primarily in forested habitats of the . Key genera include Glaucomys, which is endemic to the and contains two recognized species (northern and southern flying squirrels) adapted to North American temperate forests; Petaurista, featuring 14 species of large Asian giant flying squirrels known for their impressive size and glides exceeding 100 meters, following recent taxonomic revisions; and Pteromys, with two Eurasian species that inhabit boreal and temperate woodlands. These genera exemplify the tribe's morphological and ecological variation, from small nocturnal gliders to larger forms with specialized patagia. Molecular phylogenetic studies, utilizing and other genetic markers, reveal two primary s within Pteromyini: a Holarctic dominated by Glaucomys and closely related forms, and an Oriental encompassing most Asian genera such as Petaurista, Pteromys, and Hylopetes. Debates persist regarding subgeneric divisions, particularly in the Oriental , where morphological similarities and limited calibration complicate precise boundaries between genera like Petinomys and Aeromys. The nomenclature of flying squirrels traces back to early 20th-century morphological assessments, notably Oldfield Thomas's 1915 analysis using the (penis bone) as a taxonomic character to delineate squirrel groups, including preliminary distinctions among pteromyine forms. Subsequent refinements in the 2000s, driven by genetic data from studies like those employing sequences, have clarified and intergeneric relationships, overturning some earlier subfamily elevations to tribe status and integrating flying squirrels more firmly within .

Living species diversity

Flying squirrels, belonging to the tribe Pteromyini within the family Sciuridae, encompass approximately 56 extant species distributed across 15 genera. This diversity reflects ongoing taxonomic refinements, with recent discoveries expanding the known roster; for instance, two new woolly flying squirrel species, Eupetaurus tibetensis and Eupetaurus nivamons, were described from the eastern Himalayas in 2021 based on morphological and genetic analyses of museum specimens, alongside the description of a new genus Priapomys with P. leonardi. A 2025 study further revised the genus Petaurista, recognizing 14 species including the newly described P. nujiangensis from northwest Yunnan, China. Notable examples include the (Glaucomys sabrinus), native to , where certain such as the Carolina northern flying squirrel (G. s. coloratus) are classified as endangered due to habitat fragmentation and loss. In , the (Pteromys volans) represents a widespread across boreal forests, though it faces regional vulnerabilities from . Among the largest is the (Petaurista petaurista) of , which can reach weights of up to 2 kg and exemplifies the size variation within the group. Patterns of diversity highlight high in the Indo-Malaya , where over 30 species occur, many restricted to specific islands or forest types in regions like and . in body size is evident in several genera, such as Petaurista, where females are often larger than males, potentially linked to reproductive demands and foraging efficiency. Conservation assessments by the IUCN indicate varied statuses across the group, with about 20% of threatened; examples include the critically endangered (Biswamoyopterus sp.), impacted by in India's , underscoring broader threats like habitat loss and hunting in tropical ranges.

Fossil species and evolutionary history

The fossil record of flying squirrels (tribe Pteromyini) is sparse and primarily consists of isolated dental remains, with the earliest purported evidence dating to the late Eocene (approximately 36.6–35.8 million years ago) from the genus Hesperopetes in North America and Asia, though its assignment to gliding forms remains debated due to the absence of postcranial evidence confirming adaptations like the patagium. The oldest undisputed flying squirrel fossils appear in the early Miocene (around 23 million years ago) in Europe, including the small-bodied genus Blackia, such as B. miocaenica, known from dental specimens in deposits like those in Sansan, France, indicating early diversification among diminutive arboreal forms. These early records suggest an initial radiation tied to the expansion of forested habitats during the Oligocene, following global cooling and the proliferation of angiosperm-dominated woodlands that favored arboreal lifestyles. Key fossil genera from the provide insights into the evolution of adaptations from non-gliding arboreal squirrels within the subfamily . Notably, Miopetaurista, documented across from the early to (approximately 23–5 million years ago), includes species like M. neogrivensis, whose 11.6-million-year-old skeleton from , —the oldest known for the group—preserves diagnostic postcranial features such as elongated tarsal bones and a styliform styloid process, evidencing an early for controlled . This genus, often large-bodied and resembling modern giant flying squirrels, highlights a phylogenetic split from tree squirrels () around 36.5–24.9 million years ago, with Pteromyini diverging from ground squirrels () near the Eocene-Oligocene boundary, approximately 50 million years ago, amid the broader sciurid radiation. The saw peak diversity, with up to 10 Miopetaurista species and others like Albanensia, reflecting adaptations to diverse Eurasian forests before a contraction linked to climatic shifts. Significant gaps persist in the record, particularly for soft tissues like the , which rarely fossilize and leave gliding adaptations inferred mainly from skeletal proxies in rare articulated specimens. analyses, calibrated with fossils such as Miopetaurista, estimate the crown-group age of Pteromyini at 25–30 million years ago, aligning with late diversification of subtribes (Pteromyina and Glaucomyina) around 27–18 million years ago, though earlier Eocene origins cannot be ruled out pending better preservation. These estimates underscore the challenges of integrating fragmentary s with genetic data to reconstruct the transition from climbing to in this .

Distribution and habitats

Global range and biogeography

Flying squirrels, belonging to the tribe Pteromyini within the Sciuridae, exhibit a global distribution primarily confined to the Holarctic and Oriental realms. Their range spans , , and , with the highest diversity concentrated in and , where over 40 extant across 14 genera are found. In contrast, three occur in (Glaucomys sabrinus, G. volans, and G. oregonensis), and a single (Pteromys volans) inhabits northern from to and Korea. These squirrels are notably absent from south of the and from , reflecting the broader Sciuridae family's limited penetration into Australasian and sub-Saharan African regions due to historical dispersal barriers and ecological constraints. Populations display marked disjunctions, with isolated North American lineages contrasting sharply against the species-rich assemblages in Southeast Asian hotspots, where more than 30 species thrive amid tropical forests. Island endemics further highlight these patterns, such as the Japanese flying squirrel (Pteromys momonga) restricted to and the Taiwan giant flying squirrel (Petaurista grandis) on , resulting from Pleistocene sea-level fluctuations that promoted on isolated landmasses. Genetic analyses indicate that such disjunct distributions stem from ancient vicariance events, with low between continental and insular forms. The of flying squirrels is shaped by historical expansions and barriers, originating in during the Oligocene-Miocene transition around 23-18 million years ago (Ma), followed by mid-Miocene dispersals into and . The Bering Land Bridge played a pivotal role in Pleistocene migrations, enabling faunal exchanges between and during periods, as evidenced by records of genera like Miopetaurista across these continents. Post-glacial recolonization from southern refugia in repopulated northern latitudes in after the , supported by phylogeographic studies revealing diversity consistent with northward expansions from tropical holdouts. Uplift of the and intensification of Asian monsoons acted as barriers, limiting further westward spread and confining much of the modern diversity to eastern and southeastern .

Preferred environments and adaptations

Flying squirrels primarily inhabit old-growth forests characterized by dense canopies that provide vertical stratification for arboreal movement, with North American species favoring coniferous-dominated boreal and mixed woodlands, while many Asian species occupy tropical and subtropical broadleaf forests. These environments offer interconnected tree layers essential for their lifestyle, as evidenced by studies showing higher population densities in mature stands with multi-layered canopies compared to younger or fragmented forests. Their altitudinal range spans from to elevations exceeding 4,000 meters, particularly in the Himalayan region where like the woolly flying squirrel (Eupetaurus cinereus) thrive in high-altitude coniferous forests up to 4,800 meters. Adaptations such as denser, woolly fur in montane populations provide insulation against temperatures at higher elevations, enabling survival in climates with subzero winters and reduced oxygen levels. Microhabitat requirements include hollow trees or snags for nesting, often in live or dead trees with cavities, alongside abundant sources of mast such as and nuts from mature trees; these features support their denning and resource needs, with populations showing sensitivity to fragmentation that disrupts such structures. Downed woody debris and moist soils further enhance suitability by maintaining and fungal resources in the . Evolutionarily, gliding adaptations have enabled flying squirrels to exploit discontinuous patches by facilitating efficient travel between isolated trees, a trait that likely arose in response to fragmented arboreal habitats during their phylogenetic . Additionally, in North American flying squirrels, ultraviolet in their fur, which glows pink under UV light prevalent in dim understories, may aid in intraspecific communication or within low-light environments.

Behavior and biology

Locomotion and gliding mechanics

Flying squirrels initiate gliding by leaping from a tree branch, typically achieving takeoff speeds of approximately 5–10 m/s, followed by a brief ballistic phase before the —a furred spanning from to ankle—deploys to generate lift. This deployment creates a cambered shape, with relative camber averaging 14% of the chord length, enabling lift coefficients with mean values around 2.1 during glides. Glides cover horizontal distances of 20–60 m for smaller species like the (Glaucomys volans), with vertical drops of 20–30 m, while larger species such as the (Petaurista leucogenys) can achieve up to 50 m horizontally. Aerodynamically, the functions as a low-aspect-ratio (1.0–2.2), producing lift through high angles of attack (35–54°) that often result in flow, balanced by drag coefficients of 0.8–1.0 for stability. Flight control occurs via active adjustments: forelimbs and hindlimbs alter camber and pitch to modulate lift-to-drag ratios (averaging 2.26), while the flattened acts as a for yaw and banking during turns. High-speed reveals maneuvers including 90-degree turns around obstacles, achieved through asymmetric limb positioning and lateral accelerations up to 6 m/s², with glide speeds averaging 5–8 m/s. Gliding enhances energy efficiency compared to , with non-equilibrium dynamics allowing glide ratios of about 1.9–2.0 (horizontal distance per unit vertical drop), reducing the overall cost of arboreal travel for body masses around 0.1–0.4 kg by minimizing repeated ascents. involves deceleration through feathering—increasing drag via partial collapse—and a terminal pitch-up maneuver, limiting impact forces to levels survivable without injury. As , flying squirrels rely on enlarged eyes for low-light during glides, enabling precise adjustments in dim canopies.

Diet and foraging strategies

Flying squirrels exhibit an omnivorous diet, with primary consumption consisting of , nuts, and fungi, supplemented by , buds, flowers, fruits, and occasionally , bird eggs, or carrion depending on the and region. Northern species, such as Glaucomys sabrinus, emphasize mycophagy, relying heavily on hypogeous fungi (truffles) like those in genera Rhizopogon and Gautieria, which provide essential nutrients and are detected through keen olfaction during . Southern flying squirrels (Glaucomys volans) are more granivorous, favoring acorns, nuts, and from mast-producing trees, though they also incorporate fungi and lichens. Foraging occurs exclusively at night, leveraging their large eyes for low-light , and typically covers distances of about 1-2 km in a circular pattern from den sites, minimizing exposure to predators. These arboreal mammals rarely descend to the ground, instead using to travel between food sources in the forest canopy, which allows efficient access to dispersed resources while reducing energy expenditure and risk. Caching behaviors vary by ; southern flying squirrels store nuts and acorns in crevices, nests, or dreys for winter use, exhibiting seasonal shifts toward cached nuts when fresh mast declines. In contrast, northern flying squirrels do not cache fungi but forage widely year-round, adapting to scarcity by increasing intake (e.g., Alectoria and Bryoria ) during heavy snowfall winters when availability drops. Their foraging strategies support mutualistic relationships with mycorrhizal fungi, as flying squirrels ingest sporocarps and excrete viable spores in , facilitating fungal dispersal and enhancing , particularly in coniferous ecosystems. This mycophagy also positions them as important dispersers, as undigested nuts and fruits are dropped or cached, promoting regeneration. Nutritional adaptations include in the enlarged , enabling efficient breakdown of fibrous lichens and fungal tissues, which are staples for northern populations in -poor environments. Overall, these behaviors optimize energy intake while maintaining ecological balance, with diet diversity influenced by maturity and seasonal food pulses.

Reproduction and development

Flying squirrels exhibit varied mating systems across species, with many displaying polygynandrous or promiscuous behaviors where both males and females with multiple partners during breeding seasons. In North American like the (Glaucomys volans), breeding occurs biannually, peaking in February to March and May to July, influenced by photoperiod and food availability. The (Glaucomys sabrinus) breeds once annually in early spring, from March to late May. In contrast, tropical , such as those in , often breed year-round due to consistent environmental conditions. Gestation periods typically last 37 to 42 days in northern flying squirrels and around 40 days in southern flying squirrels, resulting in altricial young that are born blind, hairless, and weighing 2 to 6 grams. Litter sizes range from 1 to 6 , with averages of 2 to 4 in most ; southern flying squirrels produce smaller litters (2-3) in spring and larger ones (4-5) in summer. Females usually produce one or two litters per year, depending on latitude and resource availability. Newborn flying squirrels remain in the nest, cared for exclusively by the , who nurses them for 5 to 10 weeks until ; eyes open around 3 to 4 weeks, and develops by then. Juveniles begin practicing skills at about 5 to 6 weeks, achieving proficiency by 6 to 8 weeks, after which they leave the nest—around 40 days for northern species and 8 weeks for southern ones. Males do not provide direct care but may defend territories to protect resources for the family unit. is reached at 6 to 12 months. In the wild, flying squirrels have a of 3 to 5 years, limited by predation and environmental factors, while in , they can live 10 to 13 years, with records up to 19 years. is influenced by diet, as food scarcity can delay breeding or reduce litter sizes through mechanisms like restricted energy intake or disrupted .

Ecology and conservation

Predators, threats, and interactions

Flying squirrels face predation primarily from nocturnal and arboreal hunters adapted to forested environments. Common natural predators include such as the and , martens, and various snakes that ambush them at nest sites or during glides. In , hawks and weasels also pose threats, particularly to juveniles. To counter these threats, flying squirrels employ several anti-predator strategies. They remain highly vigilant, often freezing or retreating into cavities upon detecting danger, and emit calls including audible "tseep" and ultrasonic vocalizations to alert conspecifics. mechanics allow for erratic trajectories that can evade pursuing predators, enabling quick escapes over distances up to 100 . Anthropogenic threats exacerbate natural pressures on flying squirrel populations. Habitat deforestation has led to substantial forest loss in Asia, where Southeast Asian highlands experienced unexpectedly high rates of tree cover reduction since 2000, fragmenting old-growth forests essential for gliding and nesting. The illegal pet trade targets species like Vordermann's flying squirrel, contributing to population declines through capture and habitat disturbance. Climate change further alters suitable habitats by shifting temperature and precipitation patterns, potentially reducing available old-growth conifer and hardwood forests in both Asia and North America. Interspecies interactions highlight flying squirrels' ecological roles and challenges. They compete with invasive or expanding species, such as southern flying squirrels encroaching northward due to human-induced range shifts, leading to resource overlap and parasite-mediated exclusion of northern populations. Positively, flying squirrels form symbiotic relationships through seed and spore dispersal; by consuming and excreting seeds from hardwoods and spores from mycorrhizal fungi like truffles, they facilitate forest regeneration and nutrient cycling, benefiting tree communities and associated bird species that rely on dispersed seeds. Flying squirrels also serve as disease vectors in certain contexts. In , they harbor ticks carrying , the bacterium responsible for , potentially amplifying transmission in forested areas. Their role in spreading mycorrhizal fungi to trees, while ecologically beneficial, underscores their position in pathogen dynamics for forest health.

Population status and protection measures

Flying squirrel populations exhibit varied conservation statuses across their approximately 50 species, with around 20% classified as vulnerable or endangered on the , while many others remain stable in undisturbed core habitats. For instance, the Carolina northern flying squirrel (Glaucomys sabrinus coloratus), a endemic to the southern , is listed as endangered under the U.S. Endangered Species Act owing to ongoing and loss. Population trends indicate significant declines in fragmented landscapes since the 1990s, particularly in regions affected by and , though intact forest populations show relative stability. These declines are monitored through non-invasive methods such as camera traps, which offer higher detection rates than traditional live-trapping, and genetic analyses that reveal population structure and connectivity. Conservation initiatives focus on habitat protection and restoration to mitigate these pressures. Key efforts include the designation of reserves like , which preserves old-growth coniferous forests critical for the (Glaucomys sabrinus). Several Asian species, such as the (Petaurista petaurista), are listed under Appendix II to regulate international trade and prevent overexploitation. Reforestation programs in , including efforts to restore lowland forests, support habitat recovery for gliding species dependent on continuous canopy cover. Ongoing research highlights gaps in baseline data, particularly the need for comprehensive surveys in , where tropical forests harbor high diversity but limited monitoring. Climate models forecast substantial habitat losses, with some projected to experience over 85% decline in suitable by mid-century, driven by warming temperatures and altered precipitation, underscoring the urgency for strategies. As of 2025, recent studies emphasize urgent conservation needs for like the amid and climate impacts.

References

  1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8317177/
  2. https://www.mdpi.com/2075-1729/15/4/589
  3. https://animaldiversity.org/accounts/Glaucomys_sabrinus/
  4. https://bioone.org/journals/Wildlife-Biology/volume-22/issue-1/wlb.00120/Gliding-performance-of-the-red-giant-gliding-squirrel-Petaurista-petaurista/10.2981/wlb.00120.pdf
  5. https://academic.oup.com/jmammal/article/100/1/21/5299493
  6. https://doi.org/10.1007/s12595-015-0141-z
  7. https://academic.oup.com/jmammal/article/88/4/840/908936
  8. https://animaldiversity.org/accounts/Petaurista_philippensis/
  9. https://pmc.ncbi.nlm.nih.gov/articles/PMC6177260/
  10. https://academic.oup.com/jmammal/article-pdf/79/1/245/2504483/79-1-245.pdf
  11. https://adrianbowyer.com/Publications/paskins-squirrel-forces.pdf
  12. https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.23471
  13. https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.25146
  14. https://www.researchgate.net/publication/295160479_Aerodynamics_of_the_northern_flying_squirrel_Glaucomys_sabrinus
  15. https://www.adfg.alaska.gov/static/education/educators/curricula/pdfs/skulls.pdf
  16. https://www.sciencedirect.com/science/article/pii/S0031018223004066
  17. https://animaldiversity.org/accounts/Petaurillus/
  18. https://www.ecologyasia.com/verts/mammals/indian-giant-flying-squirrel.htm
  19. https://repository.si.edu/server/api/core/bitstreams/ad8129ff-be0f-4dfe-8b9d-7f751beaef10/content
  20. https://academic.oup.com/jmammal/article/89/4/852/869338
  21. https://animaldiversity.org/accounts/Glaucomys_volans/
  22. https://portal.ct.gov/deep/wildlife/fact-sheets/flying-squirrel
  23. https://bmczool.biomedcentral.com/articles/10.1186/s40850-016-0009-3
  24. https://auetd.auburn.edu/handle/10415/2793
  25. https://www.science.smith.edu/departments/biology/VHAYSSEN/sq_size.pdf
  26. https://www.adfg.alaska.gov/index.cfm?adfg=northernflyingsquirrel.printerfriendly
  27. https://animaldiversity.org/accounts/Petaurista_petaurista/
  28. https://www.ecologyasia.com/verts/mammals/red-giant-flying-squirrel.htm
  29. https://onlinelibrary.wiley.com/doi/10.1111/1749-4877.12655
  30. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0257156
  31. https://academic.oup.com/jmammal/article/104/4/892/7111432
  32. https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=337748
  33. https://www.science.org/doi/10.1126/science.1083206
  34. https://zookeys.pensoft.net/article/33678/
  35. https://academic.oup.com/zoolinnean/article/205/1/zlaf106/8266841
  36. https://www.nationalgeographic.com/animals/article/two-new-species-of-cat-size-flying-squirrels-discovered-in-the-himalaya
  37. https://pmc.ncbi.nlm.nih.gov/articles/PMC12028898/
  38. https://www.sciencedirect.com/science/article/abs/pii/S0044523120300036
  39. https://www.rewild.org/blog/finding-hope-in-conservation-the-search-for-a-lost-flying-squirrel
  40. https://news.mongabay.com/2019/09/new-species-of-giant-flying-squirrel-brings-hope-to-one-of-the-worlds-most-wanted/
  41. https://elifesciences.org/articles/39270
  42. https://www.tandfonline.com/doi/full/10.1080/02724634.2018.1537281
  43. https://onlinelibrary.wiley.com/doi/full/10.1002/spp2.1454
  44. https://repository.si.edu/bitstreams/8ca0022d-8d44-4ba9-8ec2-1551ddc16e2b/download
  45. https://academic.oup.com/jmammal/article/98/4/1027/3807034
  46. https://www.researchgate.net/publication/257718980_The_Evolution_and_Paleobiogeography_of_Flying_Squirrels_Sciuridae_Pteromyini_in_Response_to_Global_Environmental_Change
  47. https://movementecologyjournal.biomedcentral.com/articles/10.1186/s40462-016-0071-z
  48. https://www.fs.usda.gov/pnw/pubs/journals/pnw_2010_pyare001.pdf
  49. https://australian.museum/about/organisation/media-centre/squirrel-species-discovered-himalayas/
  50. https://palmoildetectives.com/2021/02/05/woolly-flying-squirrel-eupetaurus-cinereus/
  51. https://www.facebook.com/mainewildlifepark/posts/does-this-winter-weather-make-you-want-to-just-stay-inside-and-cuddle-it-does-fo/1000388818791161/
  52. https://www.sciencedirect.com/science/article/pii/S1616504704700993
  53. https://www.pa.gov/agencies/pgc/wildlife/discover-pa-wildlife/northern-flying-squirrel
  54. https://www.fs.usda.gov/pnw/pubs/journals/pnw_2010_flaherty003.pdf
  55. https://www.sciencedaily.com/releases/2019/02/190205102612.htm
  56. https://pmc.ncbi.nlm.nih.gov/articles/PMC3565731/
  57. https://journals.biologists.com/jeb/article/209/4/689/16498/The-relationship-between-3-D-kinematics-and
  58. https://www.nwf.org/Educational-Resources/Wildlife-Guide/Mammals/Flying-Squirrels
  59. https://academic.oup.com/jmammal/article/83/2/553/2373327
  60. https://thekidshouldseethis.com/post/northern-flying-squirrel
  61. https://journals.biologists.com/jeb/article/210/8/1413/17353/Take-off-and-landing-forces-and-the-evolution-of
  62. https://outdoornebraska.gov/learn/nebraska-wildlife/nebraska-animals/mammals/southern-flying-squirrel/
  63. https://webapps.fhsu.edu/ksmammal/account.aspx?o=39&t=200
  64. https://extension.umd.edu/resource/woodland-wildlife-spotlight-southern-flying-squirrel
  65. https://www.fs.usda.gov/pnw/pubs/journals/pnw_2002_carey001.pdf
  66. https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=3568&context=gbn
  67. https://newsrelease.adfg.alaska.gov/index.cfm?adfg=wildlifenews.view_article&articles_id=73
  68. https://www.sierraforestlegacy.org/Resources/Conservation/SierraNevadaWildlife/NorthernFlyingSquirrel/NFS-Thysell97.pdf
  69. https://academic.oup.com/jmammal/article/94/6/1266/903187
  70. http://middlesexcountywildlife.com/flyingsquirrelfacts.html
  71. https://academic.oup.com/jmammal/article/89/3/582/861078
  72. https://wgfd.wyo.gov/media/1411/download?inline
  73. https://www.sierraforestlegacy.org/Resources/Conservation/SierraNevadaWildlife/NorthernFlyingSquirrel/NFS-Villa99.pdf
  74. https://bmcecol.biomedcentral.com/articles/10.1186/s12898-016-0107-7
  75. https://www.chesapeakebay.net/discover/field-guide/entry/southern-flying-squirrel
  76. https://www.sciencing.com/predators-southern-flying-squirrel-8124640/
  77. https://dnr.maryland.gov/wildlife/pages/plants_wildlife/southern_flyingsquirrel.aspx
  78. https://pmc.ncbi.nlm.nih.gov/articles/PMC3757013/
  79. https://asknature.org/strategy/how-flying-squirrels-control-glide/
  80. https://news.mongabay.com/2021/06/forest-loss-in-mountains-of-southeast-asia-accelerates-at-shocking-pace/
  81. https://www.princeton.edu/news/2018/07/03/southeast-asian-forest-loss-much-greater-expected-negative-implications-climate
  82. https://palmoildetectives.com/2021/02/05/vordermanns-flying-squirrel-petinomys-vordermanni/
  83. https://india.mongabay.com/2025/06/flying-squirrel-habitats-predicted-to-tailspin-under-climate-change/
  84. https://www.researchgate.net/publication/392465448_Gliding_on_the_Edge_The_Impact_of_Climate_Change_on_the_Habitat_Dynamics_of_Two_Sympatric_Giant_Flying_Squirrels_Petaurista_elegans_and_Hylopetes_phayrei_in_South_and_Southeast_Asia
  85. https://www.frontiersin.org/journals/ecology-and-evolution/articles/10.3389/fevo.2023.1096244/full
  86. https://www.sciencedirect.com/science/article/pii/S2213224421001140
  87. https://animalia.bio/southern-flying-squirrel
  88. https://academic.oup.com/bioscience/article/62/11/950/263002
  89. https://www.fs.usda.gov/pnw/sciencef/scifi60.pdf
  90. https://aaacwildliferemoval.com/blog/squirrels/do-flying-squirrels-carry-diseases/
  91. https://www.crittercontrol.com/wildlife/flying-squirrels/
  92. https://www.adfg.alaska.gov/index.cfm?adfg=northernflyingsquirrel.uses
  93. https://ecos.fws.gov/ecp/species/2657
  94. https://esj-journals.onlinelibrary.wiley.com/doi/10.1007/s10144-013-0411-4
  95. https://www.usgs.gov/publications/comparison-survey-techniques-detection-northern-flying-squirrels
  96. https://westerntransportationinstitute.org/wp-content/uploads/2016/08/4W2988_Final_Report.pdf
  97. https://www.nps.gov/olym/learn/nature/animals.htm
  98. https://news.mongabay.com/2011/06/back-from-a-century-of-extinction-conservation-proposed-for-elusive-asian-flying-squirrel/
  99. https://www.researchgate.net/publication/242084583_Global_hotspots_and_knowledge_gaps_for_tree_and_flying_squirrels
  100. https://phys.org/news/2025-07-reveals-urgent-siberian-flying-squirrel.html
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