Northern flying squirrel  (Glaucomys sabrinus)

The northern flying squirrel is classified as Least Concern (LC) on the IUCN Red List (1).

The northern flying squirrel (Glaucomys sabrinus) is a long-whiskered, nocturnal mammal of forested areas in North America. Despite its somewhat misleading common name, the northern flying squirrel does not fly, and instead glides by extending a fold of skin that stretches from the wrists to the ankles, using the flattened tail as a rudder. The fur of this species is brown on the upperparts, fading to a buffy-white on the belly (2).

Widespread across much of North America, the northern flying squirrel is found from Alaska, east through Canada to the eastern provinces, and south into parts of the United States interior. In the western U.S., the northern flying squirrel occurs as far south as southern California (1).

Despite having a preference for cool, moist, mature coniferous forest or mixed forest, the northern flying squirrel utilises a variety of different woodland habitats, including younger stands (1) and warm, dry oak-pine forests at lower elevations (2). The northern flying squirrel frequently occupies tree cavities, leaf nests and underground burrows whilst nesting (1).

The northern flying squirrel is considered to be among the most aerodynamically sophisticated of all gliding mammals (3), able to travel anywhere between 3 and 45 metres in a single glide (4). It uses this skill to travel between trees to feed on a variety of fungi and lichens in particular, although insects, nuts, buds, seeds and fruits are also eaten. The northern flying squirrel also spends a considerable amount of time feeding on the ground (1). 

The northern flying squirrel maintains one of several dens throughout the year. In winter, this is often a cavity in a conifer tree, and, as this species does not hibernate, several individuals may share a nest to keep warm (5). During breeding, which occurs between February and July (1), the female northern flying squirrel typically selects a den in lower parts of a tree. This species may shift between different den sites, even when rearing young (5). 

One or two litters of 2 to 6 young are born each season, after a gestation period of 37 to 42 days. The young are weaned at around 2 months and reach sexual maturity at 6 to 12 months (1).

The northern flying squirrel is common in much of its very large range and, consequently, is not at immediate risk of extinction (1). There are no known major threats to this species at present, although declines of populations in the southern Appalachian Mountains led to it being listed as an Endangered Species by the U.S. Fish and Wildlife Service in 1985 (6). The main cause of this decline was habitat loss associated with forest clearing and recreational activities, although pollution and the introduction of exotic species have also negatively affected this species in the Appalachians (2).

As the northern flying squirrel is most common in healthy forests that have not been heavily impacted by human activities such as logging or land clearing, the conservation and management of its habitat is crucial to its survival (7).

Find out more about the northern flying squirrel:

• U.S. Fish and Wildlife Service:
  http://www.fws.gov/asheville/htmls/listedspecies/Carolina_northern_flying_squirrel.html