Northern Flying Squirrel

The Northern Flying Squirrel, Glaucomys sylvanus, is one of two species of the genus Glaucomys, the only flying squirrels found in North America (the other is the Southern flying squirrel, G. volans). It is chiefly found in western North America, from Alaska into California, though its range extends as far east as Maine. Two subspecies are found in the southern Appalachians, the Carolina northern flying squirrel, G. s. coloratus, and the Virginia northern flying squirrel G. s. fuscus, and these are endangered.

A major food source for the squirrels are mycorrhizal fungi (truffles) of various species, though they also eat lichens, mushrooms and beechnuts. 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.

The Northern Flying Squirrel nests in holes in trees, preferring large-diameter trunks and dead trees. 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. Except when rearing young, the squirrels shift from nest to nest frequently. They often share nests. In all but the most severe weather conditions, the squirrels are crepuscular (active at dawn and dusk), but in harsh winters in British Columbia they have a single activity period in the middle of the night.

Home ranges are up to 4 hectares for females and 50 percent higher for males.

Northern Flying Squirrels' gliding distances tend to be between 5 and 25 metres, though glides of up to 45 m 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. Glides have some tendency to be with the slope of terrain, allowing a longer glide.

In the Pacific north-west, the squirrels breed once per year, in May or June.

Northern flying squirrels, along with pine squirrels, are an important prey species for the endangered Spotted Owl Strix occidentalis. They also disseminate spores of the ectomycorrhizal fungi that they eat, and these are essential to trees of the pine family.

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