Glaucomys sabrinus griseifrons - A.H. Howell, 1934
Prince of Wales Flying Squirrel
Taxonomic Status: Accepted
Related ITIS Name(s): Glaucomys sabrinus griseifrons A. H. Howell, 1934 (TSN 632536)
Unique Identifier: ELEMENT_GLOBAL.2.102726
Element Code: AMAFB09024
Informal Taxonomy: Animals, Vertebrates - Mammals - Rodents
Kingdom Phylum Class Order Family Genus
Animalia Craniata Mammalia Rodentia Sciuridae Glaucomys
Genus Size: B - Very small genus (2-5 species)
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Concept Reference
Concept Reference: Hall, E. R. 1981a. The Mammals of North America, second edition. Vols. I & II. John Wiley & Sons, New York, New York. 1181 pp.
Concept Reference Code: B81HAL01NAUS
Name Used in Concept Reference: Glaucomys sabrinus griseifrons
Taxonomic Comments: Hall (1981) recognized three subspecies of flying squirrels in Alaska. The description of the Prince of Wales Island flying squirrel, G. c. griseifrons, in Southeast Alaska was based on few specimens (Howell 1934). However, analysis of mitochondrial DNA sequences of 56 specimens revealed fixed nucleotide differences between this subspecies and mainland subspecies G. s. zaphaeus (Demboski et al. 1998, Cook et al. 2001). Expanded studies using larger sample sizes and both nuclear and mtDNA have corroborated those analyses (Bidlack and Cook 2001, 2002), further supporting the validity of this taxon.
Conservation Status

NatureServe Status

Global Status: G5T2
Global Status Last Reviewed: 14Jan2008
Global Status Last Changed: 14Jan2008
Rounded Global Status: T2 - Imperiled
Reasons: Insular subspecies; Alaska endemic with range restricted to Prince of Wales and adjacent islands in Southeast Alaska. Population abundance and trends unknown; suspected rare and potentially declining. Associated with mature and old-growth forests. Imminent threats include significant habitat loss and fragmentation as a result of timber harvest and associated activities.
Nation: United States
National Status: N2 (14Jan2008)

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Alaska (S2)

Other Statuses

NatureServe Global Conservation Status Factors

Range Extent: 250-20,000 square km (about 100-8000 square miles)
Range Extent Comments: Restricted to Prince of Wales Island, southeastern Alaska. Specimens have been collected near Lake Bay, Klawock Lake, Sulzer (on Hetta Inlet), and Hollis (Howell 1934, Fay and Sease 1985, Van Horne 1981, 1982).

Number of Occurrences: 1 - 5
Number of Occurrences Comments: Occurs on one island.

Population Size Comments: Abundance is unknown. Walker (in Howell 1934) reported these squirrels were scarce on Prince of Wales Island in the 1920s and 1930s. McGregor (1958) subsequently verified their presence on the island. Recent trapping surveys (Van Horne 1981, 1982) also document their continued presence, but no estimates of abundance are available. A recent survey of trappers by Bob Wood (ADF&G), however, apparently suggested that squirrels are more common than the few published accounts indicate, at least on the northern third of the island (see Amaral 1985).

Overall Threat Impact Comments: Proposed timber harvest plans identify removal of 50-75% of old-growth habitat from Prince of Wales Island (U.S. Forest Service 1991). This program may impact local population numbers and distribution (Rosenberg and Raphael 1986, Hokkanen et al. 1982, Suring 1992). Extensive fragmentation of the forest without consideration for habitat and dispersal requirements could result in local extirpations throughout portions of the range and possibly reduce the long-term viability of the population (Suring 1992).

Short-term Trend: Decline of 10-30%
Short-term Trend Comments: Increasing removal of old-growth forests on Prince of Wales Island suggests that populations in some areas could be declining (Suring 1992).

Other NatureServe Conservation Status Information

Inventory Needs: A systematic survey of all suitable habitats on Prince of Wales Island is needed to obtain reliable estimates of abundance and distribution. Also, the adjacent islands should be inventoried to determine if this subspecies occurs over a broader range than is currently documented.

Protection Needs: Protect preferred habitat and dispersal corridors in areas sufficient to maintain long-term viable populations and overall genetic diversity.

Global Range: (250-20,000 square km (about 100-8000 square miles)) Restricted to Prince of Wales Island, southeastern Alaska. Specimens have been collected near Lake Bay, Klawock Lake, Sulzer (on Hetta Inlet), and Hollis (Howell 1934, Fay and Sease 1985, Van Horne 1981, 1982).

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.

Map unavailable!:
Distribution data for U.S. states and Canadian provinces is known to be incomplete or has not been reviewed for this taxon.
Endemism: endemic to a single state or province

U.S. & Canada State/Province Distribution
United States AK

Range Map
No map available.

U.S. Distribution by County Help
State County Name (FIPS Code)
AK Prince of Wales-Outer Ketchikan (CA) (02201)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
19 Prince of Wales (19010103)+, Icy Strait-Chatham Strait (19010500)+*
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
Basic Description: A tree squirrel.
Diagnostic Characteristics: Distinguished from mainland subspecies zaphaeus by darker upper parts, tail, and gliding membrane, and whiter underparts (Howell 1934).
Ecology Comments: Apparently important in dispersal of ectomycorrhizal fungi by carrying spores in the feces to disturbed sites such as burns and clearcuts. The fungi symbiotically enhance absorption of nutrients by plant roots and accelerate revegetation. Also important as prey for various avian and mammalian predators such as great horned owl, great gray owl, goshawk, and marten (Fay and Sease 1985). Gregarious in winter; huddles to conserve heat; up to nine have been found in one nest. In central Alaska, individual squirrels used 31 ha of optimal habitat while foraging, although some ranges of neighboring animals overlapped (Mowrey and Zasada 1984).
Non-Migrant: Y
Locally Migrant: N
Long Distance Migrant: N
Terrestrial Habitat(s): Forest - Conifer, Forest - Hardwood, Forest - Mixed
Special Habitat Factors: Fallen log/debris, Standing snag/hollow tree
Habitat Comments: Often associated with old-growth forests (McKeever 1960, Weigl and Osgood 1974, Weigl 1978, Suring 1992). Upland (Sitka spruce-western hemlock) old-growth forests are the primary habitat; peatland-mixed conifer forests likely contribute to breeding populations in managed landscapes (Smith and Nicholes 2003). Den sites are in natural tree cavities or woodpecker holes. Each squirrel uses multiple cavities for denning and shelter (Weigl and Osgood 1974).
Adult Food Habits: Carnivore, Frugivore, Granivore, Herbivore, Invertivore
Immature Food Habits: Carnivore, Frugivore, Granivore, Herbivore, Invertivore
Food Comments: Omnivorous; important foods include fungi, lichens, green vegetation, berries, seeds, and insects. Also eats meat, young birds, and eggs (Fay and Sease 1985). Foraging occurs in areas with abundant fungi and lichens and areas with well developed shrub layer that provides protection during on-ground foraging (Jordan 1948, Sonenshine and Levy 1981, Cowan 1936, McKeever 1960, Maser et al. 1978, Mowrey et al. 1981, McIntire and Carey 1989).
Adult Phenology: Nocturnal
Immature Phenology: Nocturnal
Phenology Comments: May remain in nest in severe winter weather.
Economic Attributes Not yet assessed
Management Summary
Biological Research Needs: Present research needs include: 1. Clarification of the taxonomic status of the subspecies. 2. Wider sampling of the subspecies' range. 3. Determination of population abundance and trends. 4. Ecological investigation of dependence of the squirrels on old-growth habitat. 5. Assessment of impacts of present logging practices on population trends and habitat use patterns. 6. Determine the impact of proposed alternate forest harvest programs (U.S. Forest Service 1991) on the long-term viability of flying squirrel populations on Prince of Wales Island.
Population/Occurrence Delineation
Group Name: Flying Squirrels

Use Class: Not applicable
Minimum Criteria for an Occurrence: Evidence of historical presence, or current and likely recurring presence, at a given location. Such evidence minimally includes collection or reliable observation and documentation of one or more individuals in appropriate habitat where the species is presumed to be established and breeding.
Separation Distance for Unsuitable Habitat: 1 km
Separation Distance for Suitable Habitat: 5 km
Separation Justification: Flying squirrels are highly mobile and surely capable of significant dispersal, though actual dispersal patterns are poorly known. Likely most dispersal is not more than a few kilometers.

Unsuitable habitat includes areas lacking or largely devoid of trees. Presumably movement across treeless gaps is minimal, hence the default minimum separation distance for unsuitable habitat.

Inferred Minimum Extent of Habitat Use (when actual extent is unknown): .3 km
Inferred Minimum Extent Justification: Based on a home range of 7 hectares.
Date: 12Mar2004
Author: Hammerson, G., and S. Cannings
Population/Occurrence Viability
U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
NatureServe Conservation Status Factors Edition Date: 03Mar2006
NatureServe Conservation Status Factors Author: West, E. W., updated by Gotthardt, T. A., and J. G. McClory
Element Ecology & Life History Edition Date: 07Oct2003

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

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  • Arbogast, B.S., K.I. Schumacher, N.J. Kerhoulas, A.L. Bidlack, J.A. Cook, and G.J. Kenagy. 2017. Genetic data reveal a cryptic species of New World flying squirrel: Glaucomys oregonensis. Journal of Mammalogy 98(4):1027?1041.

  • Bidlack, A. L., and J. A. Cook. 2001. Reduced genetic variation in insular northern flying squirrels (Glaucomys sabrinus) along the North Pacific Coast. Animal Conservation 4:283-290.

  • Bidlack, A. L., and J. A. Cook. 2002. A nuclear perspective on endemism in northern flying squirrels (Glaucomys sabrinus) of the Alexander Archipelago. Conservation Genetics 3:247-259.

  • Booth, E. S. 1946. Notes on the life history of the flying squirrel. J. Mamm. 27:28-30.

  • Cook, J. A., A. L. Bidlack, C. J. Conroy, J. R. Demboski, M. A. Fleming, A. M Runck, K. D. Stone, and S. O. MacDonald. 2001. A phylogeographic perspective on endemism in the Alexander Archipelago of southeast Alaska. Biological Conservation 97: 215-227.

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  • Cowan, I. M., and C. J. Guiguet. 1965. The mammals of British Columbia. Handbook of British Columbia Provincial Museum 11:1-414.

  • Cowan, I. McT. 1936. Nesting habits of the flying squirrel, Glaucomys sabrinus. Journal of Mammalogy 17:58-60.

  • Davis, W. 1963. Reproductive ecology of the northern flying squirrel. Master's thesis, University of Saskatchewan.

  • Demboski, J. R., J. A. Cook, and G. L. Kirkland, Jr. 1998. Glaucomys sabrinus (Shaw 1801), northern flying squirrel. Pp. 37-39 in: Hafner, D.J., E. Yensen, and G. L. Kirkland, Jr. (eds.). North American rodents: status survey and conservation action plan. IUCN/SSC Rodent Specialist Group. Gland, Switzerland and Cambridge, UK. 171 pp.

  • Fay, F.H., and J.L. Sease. 1985. Preliminary status survey of selected small mammals. Final report to U.S. Fish and Wildlife Service. Univ. of Alaska, Institute of Marine Science, Fairbanks, AK. 53 p.

  • Hall, E. R. 1981a. The Mammals of North America, second edition. Vols. I & II. John Wiley & Sons, New York, New York. 1181 pp.

  • Hokkanen, H., T. Tormala, and H. Vuorinen. 1982. Decline of the flying squirrel PTEROMYS VOLANS L. populations in Finland. Biol. Conserv. 23:273-284.

  • Howell, A. H. 1918. Revision of the American flying squirrels. North American Fauna 44:1-64.

  • Howell, A. H. 1934. Description of a new race of flying squirrels from Alaska. J. Mamm. 15:64.

  • Jordan, J.S. 1948. A midsummer study of the southern flying squirrel. J. Mamm. 29(1):44-48.

  • Maser, C., J. M. Trappe and R. A. Nussbaum. 1978. Fungal-small mammal interrelationships with emphasis on Oregon coniferous forests. Ecology 59(4):799-809.

  • McGregor, R. C. 1958. Small mammal studies on a southeast Alaska cutover area. Station Paper no. 8. Alaska Forest Research Center, U. S. Forest Service, Juneau, AK. 9 pp.

  • McIntire, P.W. and A.B. Carey. 1989. A microhistological technique for analysis of food habits of mycophagous rodents. Research Paper PNW-RP-404. U.S. Dept. Agriculture, Forest Service, Pacific Northwest Research Station. Portland, OR. 16 p.

  • McKeever, S. 1960. Food of the northern flying squirrel in north-eastern California. J. Mamm. 41:270-71.

  • Mowrey, R.A. and J.C. Zasada. 1984. Den tree use and movements of northern flying squirrels in interior Alaska and implications for forest management. Pp. 351-365. In: Meehan, W.R., T.R. Merrell, Jr. and T.A. Hanley (eds.). Fish and wildlife relationships in old-growth forests. Proceedings of a symposium ... held in Juneau, Alaska, 12-15 April 1982. American Institute of Fishery Research Biologists.

  • Mowrey, R.A., G.A. Laursen and T.A. Moore. 1981. Hypogeous fungi and small mammal mycophagy in Alaskan taiga. Proc. Alaska Sci. Conf. 32:120-121.

  • Mowry, R. A. 1982. The northern flying squirrel in Alaska. Wildlife Notebook Series. Alaska Department fo Fish & Game, Juneau, AK. 2 pp.

  • Rosenberg, K.V., and M.G. Raphael. 1986. Effects of forest fragmentation on vertebrates in douglas-fir forests. Pp. 263-272. In: Verner, J., M.L. Morrison, and C.J. Ralph (eds.). Wildlife 2000: Modeling habitat relationships of terrestrial vertebrates. Univ. of Wisconsin Press, Madison, WI.

  • Smith, W. P., and J. V. Nichols. 2003. Demography of the Prince of Wales flying squirrel, an endemic of southeastern Alaska temperate rain forest. Journal of Mammalogy 84:1044-1058.

  • Sonenshine, D.E. and G.F. Levy. 1981. Vegetative associations affecting GLAUCOMYS VOLANS in central Virginia. Acta Theriol. 26:359-371.

  • Suring, L.H. 1992. Conservation of flying squirrels in southeast Alaska. Pp. 284-296. In: Suring, L.H., D.C. Crocker-Bedford, R.W. Flynn, C.L. Hale, G.C. Iverson, M.D. Kirchhoff, T.E. Schenck II, L.C. Shea and K. Titus. A strategy for maintaining well-distributed, viable populations of wildlife associated with old-growth forests in southeast Alaska. Review draft, Juneau, AK. April 1992. 307 p.

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