John F. Pagels

PREDICTING PRESENCE AND ABUNDANCE OF A SMALL MAMMAL SPECIES: THE EFFECT OF SCALE AND RESOLUTION

Management of small mammal communities in forest ecosystems requires a working knowledge of the scales at which species presence and abundance can best be predicted. Habitat-based models were developed to characterize the distribution of a boreal relict, the southern red-backed vole, Clethrionomys gapperi, in the southern Appalachian Mountains, USA, at three hierarchical scales of analysis. Vole presence and abundance were most evident at the high-resolution (macrohabitat) scale, followed by the intermediate-resolution scale. The low-resolution model was the least effective for predicting presence or abundance and reflects the need for more resolute landscape classification systems if small mammal populations are to be accounted for in an ecologically relevant manner. Tree and shrub communities indicative of suitable vole habitat included Fraxinus pennsylvanica and Tsuga canadensis in the canopy and Carpinus caroliniana in the understory. Vole abundance increased with incidence of tree species such as Bet...

Factors influencing amphibian and small mammal assemblages in central Appalachian forests

Abstract We studied terrestrial amphibian and small mammal assemblages with drift fences and pitfall traps in five forested stands during 1987–1988 on Shenandoah Mountain in the George Washington National Forest, Virginia, USA. Eleven species of salamanders, five frogs, five shrews, and seven rodents were monitored. Amphibians were significantly more abundant in forest stands consisting of mature hardwoods than in a recent clearcut and a white pine plantation. Although there was considerable variation in abundance among species in the five stands, small mammal abundance was high in all five habitats studied. Amphibian species diversity (Shannon Index) was less than half that for small mammals because red-backed salamanders ( Plethodon cinereus ) were dominant in most assemblages. Amphibian and small mammal diversity and total species richness were not related to estimated stand age, total number of canopy trees, tree diversity, or frequency of underground rocks. Maintenance of amphibian biodiversity requires the combination of mature hardwoods and wetland habitats (e.g. wildlife ponds and seepages). Most of the small mammals encountered were habitat generalists. Management focus on mature hardwood forests would maintain populations of small mammals requiring cool, moist situations in upper-elevation habitats in the central Appalachian Mountains.

Macrohabitat and microhabitat affinities of small mammals in a fragmented landscape on the upper coastal plain of Virginia

Abstract We analyzed macrohabitat and microhabitat associations of four soricid and five rodent species in five macrohabitats on the Coastal Plain of Virginia. There were no significant differences in total small mammal abundance among macrohabitat types based on total captures/unit effort. However, abundances of four species, Cryptotis parva, Reithrodontomys humulis, Microtus pennsylvanicus and Zapus hudsonius, were significantly higher (P < 0.05) in old fields than in four forested habitats. Canonical correspondence analysis revealed that 27% of the variation in small mammal distributions was attributable to microhabitat characteristics. Three characteristics that had a particular influence on small mammal presence in forested habitats were shrub frequency (Sorex longirostris), canopy openness (S. hoyi) and diameter of downed woody debris (S. hoyi, Blarina brevicauda, Microtus pinetorum). Correlations between small mammals and microhabitat characteristics are due to local moisture gradients and structural heterogeneity. Lack of correlations between Peromyscus leucopus and any microhabitat characteristic is due to the ability of this species to obtain requirements from a variety of sources. Preservation of microhabitat characteristics like downed woody debris and understory vegetation, and certain macrohabitats (e.g., old fields), would require minimal management effort and provide suitable habitat for a diverse small mammal fauna in fragmented landscapes.

Nest Site Characteristics of the Endangered Northern Flying Squirrel (Glaucomys sabrinus coloratus) in Southwest Virginia

Abstract We investigated nest site use of the federally endangered northern flying squirrel (Glaucomys sabrinus coloratus) in southwest Virginia at Mount Rogers National Recreation Area. In second-growth and old forests, number of nests used by both sexes combined was x̄ = 3.3 ± 0.8 (females n = 3, x̄ = 2.7 ± 0.9, males n = 8, x̄ = 3.7 ± 1.2, overall range = 1–6). Nest site characteristics varied and flying squirrels used a variety of nest types including subterranean structures. We found northern flying squirrels chose larger taller nest trees regardless of nest tree type [red spruce (Picea rubens), n = 3, P = 0.04, deciduous, n = 8, P = 0.02, snags, n = 3, P = 0.01] compared to the available trees of the same type within a 200 m2 area of the nest tree. Nest sites in old forest stands (i.e., ≥125 y old) were characterized by greater downed wood (% cover/ha) that can be associated with the increased density of fungal colonies, lower snag density (n-snags/ha) that means a more open midstory for clearer glide paths, lower live-tree density (n-trees/ha) relating to clearer glide paths and lower shrub cover (% cover/ha) indicating a more open understory compared to nest sites in second-growth stands.

Plant Community Characteristics Associated with the Endangered Northern Flying Squirrel, Glaucomys sabrinus, in the Southern Appalachians

-Overstory and understory vegetation and physical parameters were sampled at sites where two endangered subspecies of the northern flying squirrel Glaucomys sabrinus are known to occur in the southern Appalachians. The 13 sites were disjunct, occurring at high elevations in mesic communities. Picea rubens was always present in the canopy (191173 trees/ha); the northernmost sites had greater densities of P. rubens and Betula lutea, while the southern sites had greater densities of Abies fraseri and Fagus grandifolia. Cluster analysis of overstory importance value data indicated the more southern sites and the more northern sites differed in species composition. In comparison the understory was highly variable among sites, both in species composition and percent cover and was therefore considered to be a poor indicator of suitable habitat for populations of G. sabrinus. Site characteristics indicate that the endangered populations of G. sabrinus may be restricted to patches of suitable habitat which remain at only a limited number of sites at high elevations in the southern Appalachian Mountains.

MESIC DECIDUOUS FOREST AS PATCHES OF SMALL-MAMMAL RICHNESS WITHIN AN APPALACHIAN MOUNTAIN FOREST

Abstract Forests of Southern Appalachia are critical habitats with respect to biodiversity, with a large portion of these forests residing on public multiuse lands. With pressure to extract timber from maturing forests, there is a need to identify the relative importance of forest types within the larger forest matrix. We examined small-mammal populations at 350 sample points across 157 km2 of forested habitat in the George Washington and Jefferson National Forests, Virginia, to determine landscape and habitat correlates of species abundance and richness. A total of 3,955 individuals representing 20 species were captured using live trap and pitfall sampling at each point during 1996 and 1997. Nine species were sufficiently common to examine their abundance relative to landscape and habitat features. We found species abundance and richness to be highest in mesic deciduous forest types, with the exception of Peromyscus leucopus. Soil moisture capacity and the proportion of mesic habitat within 100 m of the sample point were also important for several species. If mesic deciduous forest can be considered patches within a matrix of xeric forest, then the abundance of 4 species and species richness could be predicted based on the distance of the sample point to the nearest mesic patch and the abundance of 3 species inside mesic patches was related to patch size. At least 73% of mesic patches within this forest were <25 ha and separated from other patches by >100 m. Our results indicate that mesic forest patches contain the bulk of the species richness for small mammals in the Southern Appalachian ecotype. Designing timber harvests that minimize use of mesic deciduous forest type and that does not decrease patch numbers would achieve the largest benefits to small mammals within the region.

Dispersal Abilities and Genetic Population Structure of Insular and Mainland Oryzomys palustris and Peromyscus leucopus

A comparative hierarchical approach was used to examine allozymic variability within and among nine populations of Oryzomys palustris (marsh rice rat) and seven populations of Peromyscus leucopus (white-footed mouse) from the Virginia barrier islands and southern Delmarva Peninsula. O. palustris is an effective disperser over water and is present on 21 of 24 islands. In contrast, P. leucopus is a less effective disperser over water and occurs on only four of 24 islands. Of 31 loci, four were variable in O. palustris ; six were variable in P. leucopus . The nine populations of O. palustris had an average heterozygosity of 2.4% with 6.7% polymorphic loci. For seven populations of P. leucopus , the average heterozygosity was 3.6% with 12.3% polymorphic loci. Both species had lower levels of variation among mainland populations than among island populations. Populations of P. leucopus exhibited considerable genetic differentiation ( F ST = 0.180) and lower levels of gene flow ( N m = 1.14) among populations, whereas O. palustris had moderate levels of differentiation ( F ST = 0.135) and higher levels of gene flow ( N m = 1.60) among populations. Mantel tests indicated a significant relationship between genetic distance and geographic distance in Oryzomys but not in Peromyscus .

Evaluation of capture techniques for amphibian, reptile, and small mammal communities in saturated forested wetlands

We evaluate the effect of different capture techniques on estimates of species richness and diversity for several amphibian, reptile, and small mammal communities in saturated forested wetlands in southeastern Virginia and South Carolina. Each technique yields different and biased quantitative results because of variation in catchability within and among taxonomic groups. Drift fences with pitfall traps seem to be a useful technique for most taxa, but complete inventories require supplemental methods. Standardized arrays of coverboards in saturated forested wetlands may be useful only for specific taxa. Our ability to generalize about the structure of terrestrial vertebrate communities and their value in saturated forested wetlands is limited because current data sets were obtained with different capture techniques. We recommend that standardized techniques and sampling efforts be used in future assessments of vertebrate communities in saturated forested wetlands so that comparisons can be made across time and space.

Mid-winter lipid reserves of the golden-crowned kinglet

Passerine birds have relatively high weight-specific metabolic rates that increase sharply in progressively smaller species (Lasiewski and Dawson 1967). Kendeigh (1970) pointed out that small birds generally are poorly insulated and might be expected to be stressed by low ambient temperature. He suggested, therefore, that energy expenditure may be influential in determining the lower limits of body size of passerines (Kendeigh 1972, but see Kendeigh et al. 1977). High costs of endothermic temperature regulation may be avoided through overnight decreases in body temperature; it appears that nocturnal hypothermia may naturally occur in several species of small passerines (Haftorn 1972, Chaplin 1976, Bucher and Worthington 1982, Lustick et al. 1982). Direct proof is difficult to obtain; hypothermia may occur in small birds in the laboratory because of stress from caging or handling, and may not be a natural part of the daily cycle. Kinglets (Regulus spp.) might be expected to show hypothermia because they are among the smallest Temperate-Zone passerines in the world (see Kendeigh 1972, Chaplin 1982). Two species occur in North America, the Golden-crowned Kinglet (R. satrapa; body weight 5.7 g) and the Ruby-crowned Kinglet (R. calendula; 6.3 g; Kendeigh 1972). These species appear to tolerate cold and may winter as far north as southern Canada and Alaska. To our knowledge, little has been published about the utilization or storage of energy by kinglets (see Gavrilov 1972). Therefore, we undertook to measure the size of lipid depots and the amplitude of daily energy cycles in the Golden-crowned Kinglet. We hypothesized that such a bird might not be able to carry sufficient energy stores to maintain high body temperatures over long, cold, winter nights. If daily cycles of energy storage are not sufficient to fuel overnight survival, this indicates that nocturnal hypothermia must occur if the species is to survive.

Fungus Consumption by the Southern Red-backed Vole (Clethrionomys gapperi) in the Southern Appalachians

Abstract We examined fungus consumption (mycophagy) by the southern red-backed vole, Clethrionomys gapperi, at 4 sites within two mixed mesophytic forests in the southern Appalachians in 1996 and 1999. Fecal pellet analysis was used to determine the fungi consumed by 30 voles. Overall mean spore frequency, measured as the proportion of fields of view that contained a spore, was 0.68, whereas mean frequency of plant material was 0.57 and frequency of insect material was less than 0.04. Voles primarily consumed 5 types of fungi, consisting of 4 genera and Glomalean spores, although 29 unidentified spore morphotypes were also observed. Among identified spores, mean frequency of Melanogaster was greatest, followed by Coprinus, Elaphomyces and Glomalean spores. Spores of Hymenogaster were least frequent. The consistent presence of spores in fecal pellets suggests that fungi are an important food item and that C. gapperi may be an important disperser of fungal spores. Compared with previous studies, our research supports the notion that C. gapperi is a fungal generalist and analysis of vole diets may be useful for assessing the availability of fungi for other, more specialized small mammal mycophagists such as the northern flying squirrel, Glaucomys sabrinus.