The Northern flying squirrel is a North American rodent with long whiskers and a flattened tail. As a matter of fact, this mammal doesn't fly, but glides, using the fold of skin, found between its wrists and ankles. When gliding, this crease of skin extends, allowing the animal to 'fly', whereas the tail acts as a rudder. The Northern flying squirrel is a nocturnal creature that lives in forested areas. It has brown fur on the upper parts, which fades to buffy-white on the belly.
Endemic to North America, the northern flying squirrel is widely distributed throughout much of the continent form from Alaska, eastwards to Canada and the eastern provinces, southwards to interior regions of the United States, reaching southern California. The preferred habitat of this species is an area with an abundance of conifer trees. This rodent occurs in large numbers in deciduous and mixed coniferous/deciduous forests. Other suitable habitats include areas, dominated by spruce, fir, and mixed hemlocks; beech maple forests; areas with abundant growth of white spruce and birch, alternating with aspen groves.
Northern flying squirrels are social animals. They often form groups of 8 individuals, typically including matures squirrels and juveniles. In addition, multiple individuals have been known to live in the same nest. During the winter months, these squirrels gather into same-sex units in order to keep warm. Northern flying squirrels are strictly nocturnal animals. They have two periods of activity during the day: one occurs an hour after sunset, lasting around 2 hours, whereas the other begins 2 hours before sunrise, lasting for 1.5 - 2 hours. During the year, each individual may have several dens. The winter dens of this species are usually cavities in conifer trees. Since they don't hibernate, multiple individuals may live in a single den during this period to conserve heat. These rodents are one of the most aerodynamically sophisticated gliding mammals. They are able to glide for as long as 5 - 45 meters at a time (20 average), though flights as long as 90 meters have been recorded. Northern flying squirrels are terrestrial feeders, spending a lot of time looking for food. Primary forms of communication include vocalizations, scent, and touch. The most commonly heard calls of this squirrel are soft, low chirping sounds and a cluck, which is emitted when the animal is feeling danger.
Currently, there is very little information on the reproductive system of this species. They most likely have different mates during each breeding season, which means they may exhibit either polygynous (one male mates with multiple females) or polygynandrous (promiscuous) (both males and females have multiple mates) mating systems. They mate from March to late May. The gestation period lasts for 37 - 42 days, yielding 1 - 6 young with an average of 2 - 4 per year. Males usually don't participate in rearing the offspring. The babies are born undeveloped with closed eyes and ears, fused toes as well as a cylindrical tail. They are extremely tiny and weigh only 5 - 6 grams at birth. Their fused toes separate by the 6th day of their lives, while the eyes open after 31 days old. At about 40 days old, young squirrels leave the nest. Complete weaning occurs after 2 months of age, by they often continue living for their mother until 3 months old. They are ready to produce offspring during the summer following their birth.
Being widely distributed and quite common throughout its range, this squirrel is not currently threatened. However, in 1985, the U.S. Fish and Wildlife Service classified the Northern flying squirrel as Endangered due to sharp population decline as a result of habitat loss, caused by forest clearing and recreational activities. In addition, the population in the Appalachians has suffered from the introduction of non-native species.
According to IUCN, the Northern flying squirrel is common and widespread throughout its range but no overall population estimate is available. Today, this species’ numbers are stable and it is classified as Least Concern (LC) on the IUCN Red List.