Cooperative Fish and Wildlife Research Units Program: Virginia
Education, Research and Technical Assistance for Managing Our Natural Resources

Virginia Project

Micro-habitat Characteristics of Virginia Northern Flying Squirrel (Glaucomys sabrinus fuscus) Foraging Sites: Relating Structure, Composition and Soils to Habitat Identification, Conservation and Restoration Needs

August 2012 - December 2015


Participating Agencies

  • West Virginia Division of Highways

The 2008 delisting of the Virginia northern flying squirrel (Glaucomys sabrinus fuscus) was in part predicated on the fact that the known and probable distribution largely occurred on conservation lands, i.e., federal and state land, and that basic “stand-level” habitat associations were described. Moreover, a consensus of managers in the region either supported or did not object to using basic approaches to red spruce (Picea rubens) silvics as the guiding principle for enhancing and expanding flying squirrel habitat in the near- and medium-term (ca. 10-50 years). Indeed, delisting actually increased restoration opportunities, as managers did not face the regulatory paradox presented by the Endangered Species Act that makes short-term habitat degradation for long-term improvement a problematic endeavor. However, the re-listing of the flying squirrel (Friends of Blackwater et al. v. Salazar et al.,1:09-cv-02122-EGS) means that deductive associations, e.g., flying squirrels forage in spruce stands therefore flying squirrels either require or prefer spruce, are no longer sufficient as the basis to guide conservation and management. Rather, stronger cause and effect associations are needed to established that management actions such as the proposed work in the Upper Greenbrier opportunity area of the Monongahela National Forest, mitigation efforts associated with Corridor H construction or the Snowshoe Resort Habitat Conservation Plan either enhance habitat or sufficiently mitigate for planned degradation.
The preponderance of evidence clearly shows an association between red spruce communities and the Virginia northern flying squirrel in West Virginia and Virginia such as smaller home ranges in spruce-dominated sites and use greater than local scale availability (Menzel et al. 2006b, Ford et al. 2007) and higher occupancy rates (Ford et al. 2010). Numerous supported hypotheses that explain this relationship exist: structural protection from predators (Meyer et al. 2007), selection of a habitat avoided by southern flying squirrels (Glaucomys volans) and presence of preferred food resources, e.g., hypogeal fungi (Loeb et al. 2000). Still, most basic relationships are poorly described. For example, although presence of northern flying squirrels increases markedly when stands exceed 35% relative importance of red spruce (Ford et al. 2004), no micro-habitat data exists to link specific conditions such as patch configuration or stand complexity with northern flying squirrel use or abundance. These kinds of data could be useful in describing relationships to stand condition or “decadence” that would help further refine red spruce restoration or enhancement measures.
Additionally, recent work by the USDA Natural Resources Conservation Service on high elevation sites in the Monongahela National Forest has suggested that one key micro-habitat component is the presence of thick organic soil layers known as folistic epipedons (Soil Survey Staff 2010). These carbon-rich soil horizons could be a particular characteristic of good northern flying squirrel habitat (J. Teets and S. Jones, unpubl. data). Indicative of micro-sites that were not heavily burned (a combination of anthropogenic influence and perhaps specific macro- and micro-scale landform characteristics) and that also retained a red spruce component, areas with folistic epipedons might be sites that support northern flying squirrel food resources (e.g. hypogeal fungi) underneath a protective red spruce cover. The near elimination of thick organic soils following exploitative logging and burning in the late 19th and early 20th centuries (Schuler et al. 2002) may explain why northern flying squirrel home ranges are larger and relative abundances are less in the central Appalachians that in other parts of North America where the species occurs (Menzel et al. 2006b). If folistic epipedons are indeed important northern flying squirrel habitat components, then managers must to be able to identify and quantify/map their presence as a part of red spruce enhancement and restoration efforts.
We propose to conduct an examination of Virginia northern flying squirrel foraging micro-habitat characteristics from previous summer/fall home range and habitat use data from the Monongahela National Forest (McGowan Mountain, Stuart Knob and Canaan Heights) and Kumbrabow State Forest (Menzel et al. 2006b) and from squirrels that will be radio-collared and tracked in the late spring-summer-early fall 2012 and 2013 at Snowshoe Resort and the Upper Greenbrier project area of the Monongahela National Forest following the nest-box trapping, handling and radio-telemetry methods of Menzel et al. (2006b). Following an adaptation Castleberry et al. (2002)’s design to examine micro-habitat conditions used by Allegheny woodrats (Neotoma magister) in West Virginia, we will establish vegetation and soil survey plots in association with telemetry points and random points. Primary emphasis will be to determine the extent of association of foraging points with red spruce over- and mid-story cover and the presence of folistic epipedons as well as to determine if these characteristics are quantifiable in a probabilistic, predictive manager (Odom et al. 2001) that could be used to refine and modify the current Virginia northern flying squirrel predicted distribution maps (Menzel et al. 2006a). Additionally, in a more mechanistic fashion, we will attempt to compare the quality and extent of measured micro-habitat characteristics to explain the variability of northern flying squirrel home range size observed on poor (McGowan Mountain, Upper Greenbrier, Kumbrabow State Forest), fair (Stuart Knob) and quality ranges (Canaan Heights and Snowshoe Resort). Specifically, we will:
1. Calculate core-use area from 50% ADK using Hawthe’s Tool Extension from historic Virginia northern flying squirrel home ranges and foraging points (Menzel et al. 2006b); retain only points in 50% ADK. Buffer each point 1.5-2X error polygon (0.16 ha, Menzel et al. 2006b).
2. Capture, collar, and track up to 16 northern flying squirrels (cumulative) at Snowshoe and Upper Greenbrier in 2012 and 2013. Calculate home range and retain foraging points from 50% ADK as above.
3. Randomly place 2-4, 0.04 ha plots within each 0.16 ha error polygon centered on 50% ADK foraging point. Record litter cover, ground cover, understory, midstory and overstory density, species composition and diversity (Castleberry et al. 2002) along with elevation, slope gradient, aspect and terrain shape (McNab 1989). Also, at each plot, a soil pit will be dug to approximately 50 cm, or to point of refusal. The depth of the surface organic layer, and presence/absence of folistic epipedons will be assessed (Soil Survey staff 2010). If present, follistic epipedons will be sampled for total carbon content (EPA Method 440. 0), and presence of charcoal layer, and rock content. The presence of hypogeal fungi will be determined by sifting through the first few cm of mineral soil to search for sporocarps following Loeb et al. (2000).
4. Quantitatively compare micro-habitat measures and soil characteristics among plots as stratified by over-all home range size or habitat quality assignment. Use data to create spatially explicit predictive maps of potential folistic epipedon areas and “enhanced” Virginia northern flying squirrel habitat quality based on these data combined with broad elevation and cover type from Menzel et al. 2006a and updated stand-age/size class data.
Our proposed micro-habitat will occur in the context of a larger, leveraged Virginia northern flying squirrel and Carolina northern flying squirrel (Glaucomys sabrinus coloratus) research project that seeks to 1) reexamine squirrel demographics from long-term nest box data from North Carolina, Virginia and West Virginia using PROGRAM PRESENCE and PROGRAM MARK, 2) link squirrel patch occupancy, extinction and colonization to spatial metrics, i.e., elevation/high elevation connectivity, forest patch size/configuration, and forest patch composition, and 3) determine the efficacy of using full spectrum or frequency division ultrasonic detectors for surveying northern flying squirrels in the central and southern Appalachians. As a value-added benefit, telemetry data collected in the Upper Greenbrier will form baseline home range and habitat use metrics necessary for planned enhancement and restoration activities to proceed in an adaptive management fashion over the coming years. Additionally, continued description and mapping of folistic epipedons may make important contributions towards understanding the role of high elevation forests and associated organic “cold” soils in carbon sequestration.

Research Publications Publication Date
Rentch, J.A., W.M. Ford, T.S. Schuler, J. Palmer and C.A. Diggins. 2014. Release of suppressed red spruce using canopy gap creation – testing applicability for ecological restoration in the Central Appalachians. Natural Areas Journal 36:29-37. January 2016
Diggins, C.A., L.M. Gilley, C. Kelly and W.M. Ford. 2016. Comparison of survey techniques on detection of northern flying squirrels. Wildlife Society Bulletin 40:654-662 August 2016
Diggins, C.A., A. Silvis, C.A. Kelly and W.M. Ford. 2016. Home range, den selection, and habitat use of Carolina northern flying squirrels (Glaucomys sabrinus coloratus). Wildlife Research 44:427-437 October 2017
Diggins, C.A. and W.M. Ford. 2016. Microhabitat selection of the Virginia Northern Flying Squirrel (Glaucomys sabrinus fuscus Miller) Northeastern Naturalist 24(2):173-190 June 2017
C.A. Diggins, C.A. Kelly and W.M. Ford. 2016. Aberrant den use of Carolina Northern Flying Squirrels (Glaucomys sabrinus coloratus) in the southern Appalachian Mountains. Southeastern Naturalist 14:44-49 January 2016
Presentations Presentation Date
Gorman, K.M., C.A. Diggins, C.A. Kelly, R.H. Odom, L.M. Gilley and W.M. Ford. 2024. Endangered Carolina northern flying squirrel (Glaucomys sabrinus coloratus) resource selection in high elevation red spruce (Picea rubens) forests. 34th Colloquium on Conservation of Mammals in the Southeast. Hilton Head, SC. Feb 16. February 2024
Theses and Dissertations Publication Date
Diggins, C.A. 2016. Determining Habitat Associations of Virginia and Carolina Northern Flying Squirrels in the Appalachian Mountains from Bioacoustic and Telemetry Surveys. PhD Dissertation, VPI&SU, Blacksburg. June 2016