Northern Flying Squirrel (Glaucomys sabrinus)
The Northern flying squirrel’s most significant threat comes from logging practices throughout its home range. Clear-cutting and deforestation practices which create large open spaces in our forest lands eliminate the possibility for the flying squirrel to glide from tree to tree in search of prey and while establishing its territorial boundaries.
This species is closely linked and dependent upon late seral, closed canopy coniferous forest. The Northern flying squirrel nests in holes in trees, preferring large-diameter trunks and dead trees (snags), and will also build outside leaf nests called dreys. They sometimes use cavities previously created and abandoned by woodpeckers as sites for their nests. Suitable nest sites tend to be more abundant in old-growth forests, and this is where most flying squirrels can be found. One particularly important discovery suggests that the 30 to 100 meter creekside buffer typically recommended for logged areas may be too small for the Northern flying squirrels. Recent research also suggests that the flying squirrel may be a keystone species due to their habit of eating and storing truffles and in the process help spread the spores of the truffles throughout the forest ensuring their long-term viability and success. Truffles are central to forest health because they are mycorrhizae, or fungi, that integrate with tree roots in a symbiotic (mutually beneficial)relationship that helps both the truffle and the tree get nutrients from the environment.
Northern flying squirrels most often nest in fir trees that are significantly larger than any of the surrounding trees in the immediate area and are also within 100 to 150 meters of a year-round creek. Protecting these old-growth trees and forests and protecting and retaining large snags is essential in securing the preferred habitat of the flying squirrel. The flying squirrel is the primary prey species of the California spotted owl and therefore the health of Northern flying squirrel population has become an important aspect of forest management decisions.
The Northern flying squirrel is considered a management indicator species for all ten National Forests in the Sierra Nevada. The species is currently being monitored on the Plumas and Lassen National Forests though a multi-year monitoring effort. It is not considered a game species and it is illegal to kill or capture a Northern flying squirrel.
Pyare, S., and W.S. Longland. 2002. Interrelationships Among Northern Flying Squirrels, Truffles, and Microhabitat Structure in Sierra Nevada Old-growth Habitat. Canadian Journal of Forest Restoration 32, 1016-1024. (78KB PDF)
Rosenberg, D.K., R.G. Anthony, 1992. Characteristics of Northern Flying Squirrel Populations in Young Second and Old-growth Forests in Western Oregon. Canadian Journal of Zoology 70,161-166. (486KB PDF)
Waters, J.R., et.al., 2000. Northern Flying Squirrel Mycophagy and Truffle Production in Fir Forests in Northeastern California. Pacific Southwest Research Station, U.S. Forest Service, GTR-178. (498KB PDF)
California Department of Fish and Game Natural History Information --This California state website contains rather limited and old information but is a good basic background composite for the species. Choose from a drop-down list to select the animal you are interested in.