The wing-loading coefficient of northern flying squirrels is about 50 Newtons/square meter, 2-3 times that of most bats. An average 'flight' of G. sabrinus is 20 meters, though flights as long as 90 meters have been recorded. Northern flying squirrels have also been seen making full semi-circles in a single flight.
Northern flying squirrels emit a soft low chirp, and they cluck when distressed. They also use scent and touch to communicate with one another.
They have excellent senses of hearing, smell, vision, and touch.
Communication Channels: tactile ; acoustic ; chemical
Perception Channels: visual ; tactile ; acoustic ; chemical
The subspecies Glaucomys sabrinus coloratus and G. s. fuscus are threatened populations in the Appalachians. Glaucomys sabrinus coloratus, North Carolina flying squirrels were designated as endangered in 1985. Between the 1880's and the 1920's, 500,000 acres of forest supporting the two subspecies were reduced by timbering to 200 acres. Conservationists are concerned that further habitat destruction, fragmentation, and pollution will eliminate the small and vulnerable islands of high elevation habitats. The plan being implemented through the U.S. Fish and Wildlife office is the following: 1) determine the exact distribution of the two subspecies 2) protect areas with suitable habitat 3) explore the ecology of the two subspecies 4) test the response to various habitat modifications, concentrating on enhancement measures and compatible timber harvest methods. Some argue that many other populations of subspecies are also endangered, but none have been listed as of yet.
US Federal List: endangered; no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
Northern flying squirrels sometimes select den sites in houses and barns, which is undesireable due to the noisy activity at night and the litter from nests and seed caches. Northern flying squirrels can also cause problems for professional trappers in the winter, as the squirrels enter traps set for martens and minks.
Negative Impacts: household pest
Glaucomys sabrinus may be important in the dispersal of spores of mycorrhizal fungi. Northern flying squirrels may also be important in the dispersal of conifer cones, though some wonder if their activity actually impedes forest reproduction through their predation on seeds.
Ecosystem Impact: disperses seeds
Glaucomys sabrinus has a characteristic squirrel diet. They eat nuts, acorns, fungi, and lichens, supplemented by fruits, buds, sap and the occasional insect and bird egg. Northern flying squirrels diverge from many squirrels in that lichens and fungi are a large portion of the diet and are not just supplements. It is thought that northern flying squirrels hoard food for the winter, though this has not been confirmed.
Animal Foods: birds; eggs; insects
Plant Foods: seeds, grains, and nuts; fruit; sap or other plant fluids; lichens
Other Foods: fungus
Foraging Behavior: stores or caches food
Primary Diet: herbivore (Granivore ); mycophage
Glaucomys sabrinus ranges from the treeline in Alaska and Canada southward in the west to northern California and Colorado, in the middle of the continent to central Michigan and Wisconsin, and in the east to northern North Carolina and Tennessee. Island populations exist in areas of high elevation in other parts of the United States, including the southern Appalachian Mountains, the Black Hills, and the Sierra Nevada.
Biogeographic Regions: nearctic (Native )
Most often found in areas dominated by conifers, northern flying squirrels can also be relatively abundant in deciduous and mixed coniferous/deciduous forests. Glaucomys sabrinus has been found in diverse areas including regions dominated by spruce, fir, and mixed hemlocks, in beech maple forests, and in areas dominated by white spruce and birch with interspersed aspen groves. The northern flying squirrel often nests in conifers 1 to 18 meters above the ground. The nests are made of twigs and bark, and they are softened with feathers, fur, leaves, and conifer needles.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: taiga ; forest ; mountains
Most northern flying squirrels live less than four years in the wild.
Range lifespan
Status: wild: 4 (high) years.
Typical lifespan
Status: wild: 4 (high) years.
Average lifespan
Status: wild: <4 years.
Average lifespan
Status: captivity: 13.0 years.
Glaucomys sabrinus weighs between 75 and 140 grams, and ranges from 275 to 342 mm in length. It has silky grey and cinnamon brown fur, with white tipped and grey based belly hairs. Northern flying squirrels have a furred patagium (fleshy membrane) that extends from the wrist of the foreleg to the ankles of the hindleg. The tail is furred, flattened, rounded at the end, and long (80% of the length of the head and body). Glaucomys sabrinus has large black eyes, which it uses for nighttime activity. Southern flying squirrels, which appear similar to the northern flying squirrels, can be distinguished because they are smaller and the hairs on the belly are often white all the way to the base of the hair. The dental formula for Glaucomys sabrinus is 1/1, 0/0, 2/1, 3/3 = 12/10 = 22.
Range mass: 75 to 140 g.
Average mass: 132.17 g.
Range length: 275 to 342 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes alike
The main predators of northern flying squirrels are owls, hawks, martens, weasels, coyotes, and the domestic cat. They avoid predation mainly by being active at night and through their vigilance and agility in the trees.
Known Predators:
Not much information is available on the mating system of northern flying squirrels. Individuals most likely have different mates each breeding season.
Courtship begins in March and may continue until late May. One litter is born per year, and the female raises the young without the help of the male. Copulation occurs in early spring and is followed by a gestation period of 37 to 42 days. Usually, 2 to 4 young are born, though litters as small as 1 and as large as 6 have been recorded. Newborns are poorly developed; they weigh 5 to 6 grams, and they have closed eyes and ears, fused toes, and a cylindrical tail. By the sixth day the toes are separated, and the eyes open after 31 days. Young leave the nest at 40 days and are totally weaned after two months, though they may remain with the mother another month. Flying squirrels breed in the first summer after their birth.
Breeding interval: Flying squirrels breed once yearly.
Breeding season: Mating occurs between March and May.
Range number of offspring: 1 to 6.
Average number of offspring: 2-4.
Range gestation period: 37 to 42 days.
Average weaning age: 2 months.
Average time to independence: 3 months.
Average age at sexual or reproductive maturity (female): 1 years.
Average age at sexual or reproductive maturity (male): 1 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous
Average birth mass: 5.5 g.
Average number of offspring: 3.
Average age at sexual or reproductive maturity (female)
Sex: female: 210 days.
Young flying squirrels are born helpless and are nursed and cared for by their mothers until they reach independence.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)
The northern flying squirrel (Glaucomys sabrinus) is one of three species of the genus Glaucomys, the only flying squirrels found in North America.[3][4] They are found in coniferous and mixed coniferous forests across much of Canada, from Alaska to Nova Scotia, and south to the mountains of North Carolina and west to Utah in the United States. They are light brown with pale underparts and grow to a length of 25 to 37 cm (10 to 15 in). They are proficient gliders but uncoordinated walkers on the ground. They feed on a variety of plant material as well as tree sap, fungi, insects, carrion, bird eggs and nestlings. They mostly breed once a year in a cavity lined with lichen or other soft material. Except when they have young, they change nests frequently, and in winter a number of individuals may huddle together in a shared nest. Unlike most members of their family, flying squirrels are strictly nocturnal.
The northern flying squirrel is found in coniferous and mixed coniferous forests across the top of North America, from Alaska to Nova Scotia, south to the mountains of North Carolina and Tennessee and west to Utah. The Humboldt's flying squirrel was formerly considered conspecific, but was found to be a cryptic species, and now considered distinct. It is generally smaller and darker than northern flying squirrel and occurs in British Columbia, northern California, Washington and Oregon.
Two subspecies are found in the southern Appalachians, the Carolina northern flying squirrel, G. s. coloratus, and the West Virginia northern flying squirrel G. s. fuscus, both of which are endangered, although the West Virginia subspecies has recovered enough that it was delisted in August 2008.[5][6]
The U.S. Fish and Wildlife Service temporarily put the West Virginia northern flying squirrel back under protection on June 6, 2011 in response to a court order. On appeal, the delisting was reinstated in March 2013.[6]
These nocturnal, arboreal rodents have thick light brown or cinnamon fur on their upper body and greyish fur on the flanks and whitish fur underneath. They have large eyes and a flat tail. They can also be identified by their long whiskers, common to nocturnal mammals. The adult northern flying squirrel measures from 25 to 37 cm long, and their weight can range from 110 to 230 grams.
Flying squirrels do not actually fly, they glide using a patagium created by a fold of skin.[7][4] From atop trees, flying squirrels can initiate glides from a running start[4] or from a stationary position by bringing their limbs under the body, retracting their heads, and then propelling themselves off the tree.[7][4] It is believed that they use triangulation to estimate the distance of the landing as they often lean out and pivot from side to side before jumping.[3] Once in the air, they form an "X" with their limbs, causing their membrane to stretch into a square-like shape[3] and glide down at angles of 30 to 40 degrees.[4] They maneuver with great efficiency in the air, making 90 degree turns around obstacles if needed.[4] Just before reaching a tree, they raise their flattened tails, which abruptly changes their trajectory upwards, and point all of their limbs forward to create a parachute effect with the membrane to reduce the shock of landing.[3] 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 to avoid any potential predators.[3] 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.[7][4]
A major food source for the squirrels are fungi of various species, although they also eat lichens, mushrooms, all mast-crop nuts, tree sap, insects, carrion, bird eggs and nestlings, buds and flowers. The squirrels are able to locate truffles by olfaction, though they also seem to use cues such as the presence of coarse woody debris, indicating a decaying log, and spatial memory of locations where truffles were found in the past.[8][9]
The northern flying squirrel is also known to cache food for when food supplies are lower. These caches can be in cavities in trees, as well as in the squirrels' nest. Lichens and seeds are commonly cached.
The northern flying squirrel also disseminates spores of the fungi that they eat.
.jpg)
Northern flying squirrels generally nest in holes in trees, preferring large-diameter trunks and dead trees, and will also build outside leaf nests called dreys and will also nest underground. Tree cavities created by woodpeckers as suitable nest sites tend to be more abundant in old-growth forests, and so do the squirrels, though harvested forests can be managed in ways that are likely to increase squirrel numbers. Nests may also be established in buildings, including parts of occupied homes. Except when rearing young, the squirrels shift from nest to nest frequently. They often share nests during winter months, forming aggregations. Usually, aggregate nests contain 4 to 10 individuals. The sharing of nests in winter by northern flying squirrels is important in maintaining body temperature (biothermal regulation), as northern flying squirrels do not hibernate, nor do they enter torpor states.
Northern flying squirrels gliding distances tend to be between 5 and 25 metres, though glides of up to 45 m and longer have been observed. Average glides are about 5 m less for females than for males. Glide angle has been measured at 26.8 degrees and glide ratio at 1.98.
Since first documented by Shaw in 1801, the general understanding was that northern flying squirrels bred but once per year. Recently, in southern Ontario, Canada, polyestrous behaviour (two litters per year) has been documented for the first time.[10] This observation has since been confirmed by a second research team in New Brunswick, Canada.[11]
In southern Ontario, Canada, genetic evidence has recently shown hybridization with the rapid northward expansion and increased sympatry of southern flying squirrels.[12]
Northern flying squirrels, along with pine squirrels, are an important prey species for the spotted owl (Strix occidentalis) and eastern screech owl (Megascops asio).[13] Other predators include various other large birds, especially the great horned owl and hawks, as well as mammals including the American marten, the Canadian lynx, the red fox.
The northern flying squirrel (Glaucomys sabrinus) is one of three species of the genus Glaucomys, the only flying squirrels found in North America. They are found in coniferous and mixed coniferous forests across much of Canada, from Alaska to Nova Scotia, and south to the mountains of North Carolina and west to Utah in the United States. They are light brown with pale underparts and grow to a length of 25 to 37 cm (10 to 15 in). They are proficient gliders but uncoordinated walkers on the ground. They feed on a variety of plant material as well as tree sap, fungi, insects, carrion, bird eggs and nestlings. They mostly breed once a year in a cavity lined with lichen or other soft material. Except when they have young, they change nests frequently, and in winter a number of individuals may huddle together in a shared nest. Unlike most members of their family, flying squirrels are strictly nocturnal.
