Plants and Animals

Glaucomys sabrinus Northern flying squirrel

Key Characteristics

The northern flying squirrel is 10-14 inches in body length and brownish-gray in color, with white-tipped fur on its underside (southern flying squirrels are smaller with belly fur white down to the base). It has large black eyes, rounded ears and a flattened tail. A gliding membrane (patagium) bordered with dark gray to black fur connects wrists to ankles. Northern flying squirrels molt every autumn. During winter they appear lighter in color, and with fur on the soles of their feet (Long 1995, Woods 1980).

Status and Rank

US Status: No Status/Not Listed
State Status: SC - Special Concern (rare or uncertain; not legally protected)
Global Rank: G5 - Secure
State Rank: S5


CountyNumber of OccurrencesYear Last Observed
Alger 2 1974
Dickinson 1 1974
Gogebic 1 2018
Isabella 4 1989
Leelanau 1 1965
Luce 1 1966
Midland 2 2020
Oscoda 1 2020
Presque Isle 1 1998
Wexford 1 2014

Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.


Preferring old growth, closed canopy boreal or mixed hardwood-coniferous forests, the northern flying squirrel occupies interior dens, often excavated by woodpeckers, or exterior nests (dreys) from 3 to 30 feet above ground. Typical territory size is about five acres per breeding pair (Weigl 2007, Woods 1980).

Specific Habitat Needs

Snag/cavity needed in: Boreal forestDry northern forestDry-mesic northern forestMesic northern forest.

Natural Community Types

For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.

Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.

Management Recommendations

Protecting large, unfragmented forest areas, particularly those with an old growth component, as well as wooded corridors connecting such areas, is the most important management strategy for the northern flying squirrel. Fragmentation in the form of logging, residential or commercial development, and road building may impact populations in a number of ways. As the northern flying squirrel's preferred method of travel is through the canopy, thinning or clearing sections of forest may restrict free movement for purposes of breeding, and finding food and suitable nesting sites. This species has been found to view roads through its habitat as barriers which it will not cross (Weigl et al. 2002), effectually boxing it in where a forest patch is surrounded by roads on all sides. Additionally, fragmentation and increased edge area alters moisture levels and microhabitat conditions on the forest floor, which may impact foraging behavior and food availability (Pyare and Longland 2002). Increased risk of predation by domestic cats near residential areas (Woods 1980) and by coyotes, foxes and birds of prey along roadways (Weigl 2007) has also been noted.

Active Period

Breeding from second week of March to second week of April

Parturition from first week of May to fourth week of May

Survey Methods

A common, effective method for conducting flying squirrel surveys includes both capture by hand from tree cavities and setting live traps in suitable habitat (Laves and Loeb 2006).

Live trap

Survey Period: From first week of April to fourth week of March


Survey References

  • Laves, K.S. and S.C. Loeb. 2006. Differential Estimates of Southern Flying Squirrel (Glaucomys volans) Population Structure Based on Capture Method. American Midland Naturalist 155(1): 237-243.

Technical References

  • Long, K. 1995. Squirrels: A Wildlife Handbook. Johnson Books, Boulder, CO. 181pp.
  • 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 Research 32:1016-1024.
  • Ritchie, L.E., M.G. Betts, G. Forbes and K. Vernes. 2009. Effects of landscape composition and configuration on northern flying squirrels in a forest mosaic. Forest Ecology and Managment 257(9):1920-9.
  • Wiegl, P.D. 2007. The Northern Flying Squirrel (Glaucomys sabrinus): A Conservation Challenge. Journal of Mammology 88(4):897-907.
  • Wiegl, P.D., R.S. Hughes and D.C. Battle. 2002. Study of the northern flying squirrel populations along the Cherohala Skyway: questions of fragmentation and ecology in the southernmost part of the range. Final report to the North Carolina Department of Transportation and U.S. Fish and Wildlife Service.
  • Woods, S.E. 1980. The Squirrels of Canada. National Museums of Canada, Ottawa. 199pp.