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Southern flying squirrels (Glaucomys volans) use multiple nest trees for foraging and protection, but nest trees can become scarce following harvests of hardwood forests. In northern Wisconsin, the Managed Old-growth Silvicultural Study tested techniques to remediate logging impacts on forest-dependent wildlife. Three types of canopy treatments were applied (multicohort harvest [0.4-ha and 1.2-ha irregular group shelterwoods], medium gaps [18-m- and 24-m-diameter gaps], and small gaps [11-m-diameter gaps]). To evaluate the effects of treatment on nest tree selection by southern flying squirrels, we tracked 33 radiocollared southern flying squirrels once a week for 5 weeks in late summer, locating 82 nest trees (X = 2.73 nest trees per southern flying squirrel [95% confidence interval: 2.28-3.18 nest trees]). Canopy treatments were important predictors of nest tree switching. Probability of switching differed by canopy treatment (listed from lowest to highest probability): multicohort harvest: 0.29 (0.17-0.42), medium gaps: 0.44 (0.32-0.56), control: 0.57 (0.41-0.73), and small gaps: 0.73 (0.61-0.85). Lower nest tree switching in the multicohort harvest compared to the small gaps likely reflected availability of habitat resources. Spatial arrangement of canopy gaps and associated effects on southern flying squirrels should be considered when planning timber harvests in northern hardwoods.
Key words: canopy gaps, Glaucomys volans, optimal foraging, radiotelemetry, uneven-aged silviculture
© 2012 American Society of Mammalogists
DOI: 10.1644/11-MAMM-A-032.1
Southern flying squirrels (Glaucomys volans) rely on nest trees for shelter, foraging centers, and social gatherings (Holloway and Malcolm 2007; Muul 1968; Weigl 1968; Wells-Gosling 1985). Nests protect southern flying squirrels from predators such as owls (Strigiformes), raccoons (Procyon lotor), weasels (Mustela-Wells-Gosling 1985), and rat snakes (Elaphe-Rudolph et al. 2009; Taulman et al. 1998). Tree cavities in particular provide secure resting places for northern flying squirrels (Glaucomys sabrinus) because these dens are less penetrable by predators than leaf nests (Carey et al. 1997). Nest sites also shelter southern flying squirrels during cold precipitation events (Bendel and Gates 1987), and nest cavities that can be shared by multiple southern flying squirrels are important for seasonal thermoregulation (Muul 1968; Stapp et al. 1991). Additionally, southern flying squirrels often select nest trees in close proximity to food resources such as mast-producing trees (i.e., oaks [Quercus] and hickories [Carya]-Fridell and Litvaitis 1991; Holloway 2006). With nearby food resources, nest trees serve as important sites...