Northern flying squirrel
Glaucomys sabrinus
Mammal
A nocturnal conifer-forest squirrel that glides between trunks on a membrane stretched from wrist to ankle, steering with a broad flattened tail. Its importance to the forest is mostly underground: it feeds heavily on truffles, the fruiting bodies of the mycorrhizal fungi that sheathe conifer roots, and passes the spores in its droppings. The squirrel is how those fungi reach a new tree, which makes the tie to the conifers a three-way one.
Conservation
Widespread and secure across the boreal forest, but the southern Appalachian populations are a different story: they are relicts stranded in high-elevation spruce-fir since the last glaciation, cut off from the main range, and tracked separately as their own subspecies. What threatens them is the loss and fragmentation of that narrow band of montane conifer, not pressure on the species as a whole.
Plants in the catalog
Shelter plants · 7
Balsam fir forest is core northern flying squirrel range, and the species dens in cavities and in the dense witch-broom growths that fir broom rust (Melampsorella caryophyllacearum) induces on fir branches - a defect from a timber point of view and a nest site from the squirrel one. Marked plausible rather than documented because the denning association is reported for fir-spruce forest generally rather than as a published record on Abies balsamea specifically.
Dens in cavities in these forests and feeds heavily on truffles, the underground fruiting bodies of the mycorrhizal fungi that sheathe Douglas fir roots. It passes the spores in its droppings, so it helps carry the fungal partner the tree depends on to new ground.
Dens in cavities in these stands and glides between the trunks at night. Its truffle-heavy diet also disperses the spores of the mycorrhizal fungi hemlock roots depend on, so the tie runs through the soil as well as the canopy.
Dens in cavities and old woodpecker holes in these stands and glides between trees at night. Its main food is hypogeous truffles, so it disperses the spores of the mycorrhizal fungi that grand fir roots depend on - a relationship that runs underground rather than through the cones, and one reason old rot-hollowed firs are worth leaving standing.
The tightest wildlife tie on this species, and a conservation one. Northern flying squirrels feed heavily on truffles - the fruiting bodies of the mycorrhizal fungi sheathing conifer roots - and disperse the spores, so the relationship runs three ways between squirrel, fungus and tree. Two isolated southern subspecies depend on high-elevation red spruce and northern hardwood forest: the Carolina northern flying squirrel, federally listed endangered in 1985 and still listed, and the West Virginia northern flying squirrel, listed the same year and successfully DELISTED in 2013 after habitat recovery. Restoring red spruce is the stated mechanism in both cases, and more than 7,455 acres of West Virginia habitat were created, protected or restored in the five years after delisting.
Dens in cavities and witches-broom clumps in spruce-fir stands and glides between trees at night. Its relationship with the fir runs partly underground: it feeds heavily on truffles and disperses the spores of the mycorrhizal fungi that the fir roots depend on, so the tree and the squirrel are linked through the soil as much as through the branches.
Dens in cavities in these stands and glides between them at night. Its truffle diet disperses the spores of the mycorrhizal fungi on fir roots, a relationship that runs underground rather than through the cones.
Range
Conifer and mixed forest across Alaska and Canada, south through the Rocky Mountains and the Sierra Nevada, around the Great Lakes and New England, and down the Appalachians. Since the 2017 split of Humboldt’s flying squirrel the Pacific coastal populations are treated by many authorities as a separate species, so this record describes the narrower post-split concept.
Sources & citations
Cite this page
Use this citation for the Plotwright wildlife record. Use the source cards below to explore the references that informed its taxonomy, range, conservation, host plants, foraging, and habitat.
Plotwright. (n.d.). Northern flying squirrel (Glaucomys sabrinus). Retrieved 2026, August 20, from https://plotwright.com/wildlife/northern-flying-squirrel
Sources used for this record
This record is compiled from the sources below.
Animal Diversity Web: Glaucomys sabrinus
Species account for gliding, nocturnal habits, the hypogeous-fungi diet and spore dispersal, cavity nesting, and the isolated Appalachian populations.
GBIF: Glaucomys sabrinus
GBIF backbone key 2437331 is an exact accepted match in family Sciuridae. Note the backbone carries NO record for Glaucomys oregonensis, so GBIF occurrence data for this name still includes the Pacific coastal populations that the 2017 split moved to Humboldt’s flying squirrel.
iNaturalist: Glaucomys sabrinus
iNaturalist taxon 46266 is the active species record and DOES recognise the split, carrying Glaucomys oregonensis separately as taxon 553059. Its range data is therefore the narrower concept, and differs from GBIF on the Pacific coast.
Wikipedia: Northern flying squirrel
Corroborating reference for the truffle diet and spore dispersal, the 2017 species split, and the relict Appalachian subspecies.