Southern flying squirrels are often the most common squirrel in hardwood woodlands and suburban areas. Because they are nocturnal and seldom seen, most people don't recognize that they live with flying squirrels.
Southern flying squirrels have very large eyes in order to see well in low light. They have keen senses of smell, touch, vision, and hearing. They probably communicate about reproductive condition through chemical cues. Vibrissae on the cheeks, chin, and ankles help them in navigating at night. They are relatively quiet but may use some vocalizations in social communication.
Communication Channels: tactile ; acoustic ; chemical
Perception Channels: visual ; tactile ; acoustic ; chemical
Some subspecies in Central America are rare and may be endangered.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
Flying squirrels are sometimes pests when they make nests in houses.
Flying squirrels play important ecosystem roles in hardwood forests. They are also sometimes kept as pets.
Positive Impacts: pet trade
Flying squirrels consume large numbers of the fruiting bodies of subterranean fungi, dispersing the spores in their feces. The mycelia of these fungi form close associations with the roots of many species of trees and are believed to be essential for tree growth and maintenance. They also disperse the seeds of hardwood trees.
Ecosystem Impact: disperses seeds
Southern flying squirrels are omnivores and eat a wide range of foods, including nuts, acorns, seeds, berries, fruit, moths, junebugs, leaf buds, bark, eggs and young birds, young mice, insects carrion, and fungus. They are especially fond of hickory nuts and acorns; one sure sign of the presence of this species is piles of gnawed hickory nuts at the base of large hickory trees. They will store food for winter use.
Animal Foods: birds; eggs; carrion ; insects
Plant Foods: leaves; wood, bark, or stems; seeds, grains, and nuts; fruit
Other Foods: fungus
Foraging Behavior: stores or caches food
Primary Diet: omnivore
Glaucomys volans is found in southeastern Canada, the eastern United States, and south as far as Mexico and Honduras.
Biogeographic Regions: nearctic (Native ); neotropical (Native )
Southern flying squirrels are found in woodlands. They seem to prefer seed-producing hardwoods, particularly maple, beech, hickory, oak, and poplar. They are also found in mixed conifer/deciduous forests.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: forest
Southern flying squirrels in the wild can live to 5 or 6 years old. In captivity they have been known to live up to 10 years. Most flying squirrels probably die in their first year of life.
Range lifespan
Status: captivity: 10 (high) years.
Typical lifespan
Status: wild: 6 (high) years.
Average lifespan
Status: captivity: 12.0 years.
Flying squirrels are easily distinguished by the "gliding membrane", a flap of loose skin that extends from wrist to ankle. The loose skin along the side of the body is supported by cartilaginous spurs on the wrists and ankles. The soft fur on the back and tail is grey with varying amounts of grey tinge; the belly is white. The tail is dorso-ventrally flattened. The eyes are very large, probably related to the nocturnal habits and the visual requirements of gliding. Total length is 21.1 to 25.7 cm and tail length is 7.9 to 12 cm.
Range mass: 46 to 85 g.
Average mass: 65.38 g.
Range length: 21.2 to 25.7 cm.
Other Physical Features: endothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: sexes alike
Average basal metabolic rate: 0.414 W.
Flying squirrels avoid predators by being nocturnal and by being fast and agile in the trees and during their glides. They are alert for predators constantly. The most successful predators on flying squirrels are able to fly, such as hawks and owls, or can climb well, such as domestic cats, bobcats, weasels, raccoons, and climbing snakes.
Known Predators:
Anti-predator Adaptations: cryptic
Little is known about the mating system in southern flying squirrels. Males and females do not associate much beyond breeding.
Not much is known about mating in southern flying squirrels.
Mating System: polygynous
Females are polyestrous and typically mate twice per year. Births thus have two peaks, from February to May and from July to September. There is, however, some geographic variation in the timing of births. (In Michigan, they court and breed in winter and early spring.) The gestation period is 40 days. Litters can range from one to six young, though two or three is most common. The young are weaned at 65 days (an unusually long time for an animal this small) and are independent at 120 days. Maturity is usually attained at twelve months, though ages as young as nine months have been reported.
Breeding interval: Southern flying squirrels breed twice each year.
Breeding season: Breeding occurs from January to April and from June to August.
Range number of offspring: 1 to 6.
Average number of offspring: 2-3.
Average gestation period: 40 days.
Average time to independence: 120 days.
Range age at sexual or reproductive maturity (female): 9 (low) months.
Average age at sexual or reproductive maturity (female): 12 months.
Average age at sexual or reproductive maturity (male): 12 months.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); viviparous
Average birth mass: 3.35 g.
Average gestation period: 40 days.
Average number of offspring: 4.
Young flying squirrels are born naked and helpless in their mother's nest. Their ears open at 2 to 6 days old, they develop some fur by 7 days old, and their eyes open by their 24th or 30th day of life. Females care for their young in the nest and nurse them for 65 days, which is an unusually long time for an animal of this size. The young become independent by 4 months old unless they are born later in the summer, in which case they usually overwinter as a family.
Parental Investment: altricial ; female parental care
The southern flying squirrel or the assapan (Glaucomys volans) is one of three species of the genus Glaucomys and one of three flying squirrel species found in North America. It is found in deciduous and mixed woods in the eastern half of North America, from southeastern Canada to Florida. Disjunct populations of this species have been recorded in the highlands of Mexico, Guatemala, and Honduras.
Southern flying squirrels have grey-brown fur on top with darker flanks and are a cream color underneath. They have large dark eyes and flattened tails. They have a furry membrane called a patagium that extends between the front and rear legs and is used to glide through the air. Total length (including tail) is 21–26 cm (8.3–10.2 in). The tail can be 8–12 cm (3.1–4.7 in).
Southern flying squirrels are nocturnal. They feed on fruit and nuts from trees such as red and white oak, hickory, and beech. They store food, especially acorns, for winter consumption. They also dine on insects, buds, mushrooms, mycorrhizal fungi, carrion, bird eggs, nestlings, and flowers. Predators include snakes,[4] owls, hawks and raccoons. Domestic cats can also be potential predators.
Both in the wild and in captivity, they can produce two litters each year (with 2–7 young per litter). The gestation period is approximately 40 days. Young are born without fur or any capabilities of their own. Their ears open at 2 to 6 days old, and fur grows in by 7 days. Their eyes do not open until they are 24–30 days old. Mothers wean their young 65 days after they are born. The young then become fully independent at around 120 days of age.
Southern flying squirrels show substantial homing abilities and can return to their nests if artificially removed to distances of up to a kilometer. Their home ranges may be up to 40,000 square meters for females and double that for males, tending to be larger at the northern extreme of their range.
Exposure to southern flying squirrels has been linked to cases of epidemic typhus in humans.[5] Typhus spread by flying squirrels is known as "sylvatic typhus" and the Centers for Disease Control and Prevention has documented a total of 39 such cases in the U.S. from 1976 to 2001.[6] The squirrel acts as host to the Rickettsia prowazekii bacteria and transmission to humans is hypothesized to occur via aerosolized feces of the fleas and lice associated with G. volans.[7]
Flying squirrels do not actually fly, but rather glide using a membrane called a patagium.[8][9] From atop of trees, flying squirrels can initiate glides from a running start [9] or from a stationary position by bringing their limbs under the body, retracting their heads, and then propelling themselves off the tree.[8][9] It is believed that they use triangulation to estimate the distance of the landing area as they often lean out and pivot from side to side before jumping.[10] Once in the air, they form an "X" with their limbs by spreading their long arms forward and out and their long legs backward and out, causing their membrane to stretch into a square-like shape [10] and glide down at angles of 30 to 40 degrees.[9] They maneuver with great efficiency in the air, making 90 degree turns around obstacles if needed.[9] Just before reaching a tree, they raise their flattened tails that abruptly changes their trajectory upwards, and point all of their limbs forward to create a parachute effect with the membrane in order to reduce the shock of landing.[10] The limbs absorb the remainder of the impact, and the squirrels immediately run to the other side of the trunk or to the top of the tree in order to avoid any potential predators.[10] Although graceful in flight, they are very clumsy walkers and if they happen to be on the ground in the presence of danger, they will prefer to hide rather than attempt to escape.[8][9]
The southern flying squirrel is found in eastern deciduous forests or mixed forests of North America.[9] Large hickory[11] and beech trees[11][12] are more abundant in intensively used areas of their home ranges. Also, maple and poplar,[8][9] as well as oak trees make favorable habitat.[8] Although southern flying squirrels may be present in heavily wooded suburban regions, they never occur in large numbers in these areas.[8]
The size of the home range of southern flying squirrels varies greatly.[13] Average home range estimates are 2.45 hectares,[13] 9.0 hectares,[14] and 16.0 hectares [11] for adult males, 1.95 hectares,[13] 3.9 hectares,[14] and 7.2 hectares [11] for adult females, and 0.61 hectares for juveniles.[13] Significant overlap exists among the home ranges.[11][13][14] Near the northern limit of the southern flying squirrels distribution, home range increases in size as mast-producing trees become more dispersed.[11] This trend is also observed in fragmented forests where nesting and foraging areas become widely spaced.[15]
Home range is larger in males than females[11][13][14][15] possibly to increase the chance of encountering potential mates.[11] Although males have a larger home range, female home ranges have been shown to increase by as much as 70 percent following the departure of the offspring.[13]
Number of nesting sites does not influence the total number of flying squirrels[16] but may influence which sex will be present.[11] Male home ranges contain more food as they have been associated with a higher than expected number of large red oaks and white oaks, whereas female home ranges contained lower food resources and more abundant nesting sites possibly to avoid contact with other squirrels while raising the young.[11]
Southern flying squirrels nest in natural cavities and woodpecker holes,[12][16][17] or build nest out of leaves and twigs.[12][16] Leaf nests are used as a refuge or a resting site and are used primarily in summer, whereas cavities are used for breeding and more intensively during winter.[16] Cavities used by southern flying squirrels are found in small snags, average 23.27 cm (9.16 in) diameter at breast height, or large living trees, average 50.42 cm (19.85 in) dbh, with entrances that average 4.7 cm (1.9 in) in width by 9.4 cm (3.7 in) in height which are an average of 6.36 m (20.9 ft) above the ground.[13]
Dens tend to be on the perimeter of the home range[13][14] and situated away from clearings.[13] To cross disturbances such as plantations and logged areas, southern flying squirrels prefer to use mature forest corridors over younger ones, suggesting that they are more sensitive to forest disturbances than previously believed.[15]
Southern flying squirrels are highly social mammals and have been observed flying and foraging together in large groups.[8] Additionally, they often aggregate together in dens, especially as seasonal temperatures decline[18][19] in order to conserve energy.[20][21] Compared to individuals who nest alone in winter, squirrels in aggregates can save 30 percent more energy.[20] Although southern flying squirrels do show a preference for relatedness, they are tolerant of nonrelated but familiar individuals, possibly because in addition to providing heat energy for the aggregation, outsiders will promote outbreeding.[22] However, in the summer months they tend to forage and cahce alone in their home range.
Mull[23] stated that communal nesting may actually be detrimental during warm weather and is unnecessary in the southern parts of the species range. However, Layne and Raymond[18] observed nest boxes in Florida and discovered that the southern populations also nest in large groups (up to 25 individuals) and that, compared to northern populations, the period of elevated communal nesting extended later in the spring. In this study, nest temperatures occasionally exceeded 38°C[18] while the normal body temperature of southern flying squirrels varies between 36.3 and 38.9°C.[21] Since southern populations breed later in the spring than northern populations,[19][24] these findings suggests that communal nesting serves more than a thermoregulatory function and may actually play a role in the social organization of populations.[18] Proposed advantages of aggregation include increased likelihood of mating, increased defense against predators, or increased foraging success.[18]
Populations which nest together were found to be more highly related than expected by chance and it is believed this could be a form of kin selection since an individual's stored food may be beneficial for the survival of its relatives in the event of death.[22][25]
Winterrowd and Weigl[26] performed experiments in controlled conditions to determine whether memory, smell, random searching, or problem solving played the major role in retrieving hidden food. When burying dry nuts in dry substrate, no odors are present and spatial memory is the most effective retrieval mechanism, suggesting that there is no inclusive fitness involved in the hoarding behavior.[26] However, once placed in a wet environment, smell becomes an effective means to retrieve the food and decreases the individuals advantage over the other members of the group.[26] Experiments to determine whether a squirrel would steal from others in the group revealed that no particular pattern exists and that the hidden food is recovered according to its availability.[26]
Murrant, Bowman, J., & Wilson, P. J. (2014). A test of non-kin social foraging in the southern flying squirrel (Glaucomys volans). Biological Journal of the Linnean Society, 113(4), 1126–1135. https://doi.org/10.1111/bij.12385
The southern flying squirrel or the assapan (Glaucomys volans) is one of three species of the genus Glaucomys and one of three flying squirrel species found in North America. It is found in deciduous and mixed woods in the eastern half of North America, from southeastern Canada to Florida. Disjunct populations of this species have been recorded in the highlands of Mexico, Guatemala, and Honduras.
