Abstract
ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 27:131-140 (2015) - DOI: https://doi.org/10.3354/esr00662 Predictive habitat models derived from nest-box occupancy for the endangered Carolina northern flying squirrel in the southern Appalachians W. Mark Ford1,*, Andrew M. Evans2, Richard H. Odom3, Jane L. Rodrigue4, Christine A. Kelly5, Nicole Abaid6, Corinne A. Diggins7, Douglas Newcomb8 1U.S. Geological Survey, Virginia Cooperative Fish and Wildlife Research Unit, Blacksburg, VA 24061, USA 2Department of Geography, Texas Agricultural and Mechanical University, College Station, TX 77843, USA 3Geospatial and Environmental Analysis, Virginia Tech, Blacksburg, VA 24061, USA 4U.S. Forest Service Northern Research Station, Princeton, WV 24740, USA 5North Carolina Wildlife Resources Commission, Asheville, NC 28803, USA 6Department of Engineering Science and Mechanics, Virginia Tech, Blacksburg, VA 24061, USA 7Department of Fisheries and Wildlife Conservation, Virginia Tech, Blacksburg, VA 24061, USA 8U.S. Fish and Wildlife Service, North Carolina Field Office, Raleigh, NC 27606, USA *Corresponding author: wmford@vt.edu ABSTRACT: In the southern Appalachians, artificial nest-boxes are used to survey for the endangered Carolina northern flying squirrel (CNFS; Glaucomys sabrinus coloratus), a disjunct subspecies associated with high elevation (>1385 m) forests. Using environmental parameters diagnostic of squirrel habitat, we created 35 a priori occupancy models in the program PRESENCE for boxes surveyed in western North Carolina, 1996-2011. Our best approximating model showed CNFS denning associated with sheltered landforms and montane conifers, primarily red spruce Picea rubens. As sheltering decreased, decreasing distance to conifers was important. Area with a high probability (>0.5) of occupancy was distributed over 18662 ha of habitat, mostly across 10 mountain ranges. Because nest-box surveys underrepresented areas >1750 m and CNFS forage in conifers, we combined areas of high occupancy with conifer GIS coverages to create an additional distribution model of likely habitat. Regionally, above 1385 m, we determined that 31795 ha could be occupied by CNFS. Known occupied patches ranged from <50 ha in the Long Hope Valley in North Carolina to approximately 20000 ha in the Great Smoky Mountains National Park along the North Carolina-Tennessee boundary. These findings should allow managers to better define, protect and enhance existing CNFS habitat and provide a basis for future surveys. Owing to model biases, we view this as only a first approximation. Further research combining den selection with foraging habitat use across the full range of elevations, landforms and forest types is needed to increase predictive accuracy of CNFS distribution and sub-population viability. KEY WORDS: Carolina northern flying squirrel · Topographic gradients · Nest-box · Occupancy · Red spruce-Fraser fir · Southern Appalachians Full text in pdf format PreviousNextCite this article as: Ford WM, Evans AM, Odom RH, Rodrigue JL and others (2015) Predictive habitat models derived from nest-box occupancy for the endangered Carolina northern flying squirrel in the southern Appalachians. Endang Species Res 27:131-140. https://doi.org/10.3354/esr00662 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 27, No. 2. Online publication date: March 06, 2015 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2015 Inter-Research.
Highlights
Managers tasked with conserving endangered species often are handicapped by limited available information on distribution and habitat associations
As a post-Pleistocene relict restricted to these high-elevation ‘sky-islands’, the habitat of the naturally rare Carolina northern flying squirrel (CNFS) was further fragmented and altered by exploitative logging and widespread forest burning in the late 19th through mid-20th century (Weigl 2007)
Increasing CNFS occupancy was positively related to decreasing distance to montane conifer forests and decreasing topographic exposure (Fig. 2)
Summary
Managers tasked with conserving endangered species often are handicapped by limited available information on distribution and habitat associations. As a post-Pleistocene relict restricted to these high-elevation ‘sky-islands’, the habitat of the naturally rare CNFS was further fragmented and altered by exploitative logging and widespread forest burning in the late 19th through mid-20th century (Weigl 2007). This reduced habitat extent in remaining montane boreal forests and/or those in the process of successional recovery are threatened by exotic insect pests, atmospheric deposition, climate change and continued fragmentation processes (Nowacki et al 2010, Kelly et al 2013). The presence of southern flying squirrels has resulted in parasite-mediated competition from the intestinal nematode Strongyloides robustus, thought to be detrimental to CNFS populations, whereas southern flying squirrel populations exhibit some resistance (Krichbaum et al 2010)
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