150 Yahner et al.: Long-Term Trends in Small Mammals Table 1. Number of individual small mammals (number of animals recaptured in parentheses) captured by cover type on the SGL 33 Research and Demonstration Area, May through November 2004 and 2005.* (continued) Month November Cover type Short shrub Short shrub Cane thicket Forb-grass Forb-grass Forb-grass Grass Total number of species Total number of individuals *Scientific names of small mammals are given in the text. SGL 33 was much more diverse than that found on the ROW at the Green Lane Research and Demonstration Area in southeastern Pennsylvania (Montgomery County) in 2005, where only three species were noted; also, only 5.4 individu- als/100 TN in all cover types combined were recorded on the Green Lane ROW in 2005 (Yahner et al. 2005). Of the eight species recorded on the ROW in 2004 and 2005 combined, the most common was the white-footed mouse (Peromyscus leucopus; n60 individuals [49.6% of total individuals]), meadow vole (Microtus pennsylvanicus; n 29 [24.0%]), deer mouse (P. maniculatus; n 14 [11.6%]), eastern chipmunk (Tamias striatus; n7 [5.8%]), northern short-tailed shrew (Blarina brevicauda; n 6 [5.0%]), southern red-backed vole (Clethrionomys gapperi; n2 [1.7%]), ermine (Mustela erminea; n2 [1.7%]), and masked shrew (Sorex cinereus; n 1 [0.8%]) (Table 1). White-footed mice were ubiquitous on the ROW with cap- tures occurring in each of the cover types in 2004 to 2005; this species is probably the most common small mammal in wooded habitats throughout Pennsylvania (Merritt 1987). Eastern chipmunks, deer mice, and meadow voles were noted in at least three different cover types in the 2 years. Species found on the ROW in 2004 and 2005 but not in 1989 and 1990 were deer mouse and ermine; conversely, species found in 1989 and 1990 on the ROW but not in 2004 and 2005 were one each of woodland (Napaeozapus insignis) and meadow jumping mice (Zapus hudsonicus) (Bramble et al. 1992). Number of species and total individuals of all species com- bined (percentage of total individuals and number of indi- viduals of all species combined/100 TN given in parentheses) varied among cover types on SGL 33 in 2004 and 2005 combined: grass 2 species, 11 individuals (9.1% of total individuals, 0.9 100/TN); forest 2 species, 20 individuals (16.5%, 1.7); tall shrub 3 species, 15 individuals (12.4%, 1.3); both cane thicket and forb-grass each 5 species, 28 individuals (23.1%, 2.4); and short shrub 6 species, 6 individuals (5.0%, 0.5) (Table 1). Hence, like in a previous study (Bramble et al. 1992), the forest cover type tended to be ©2007 International Society of Arboriculture less diverse in terms of number of mammal species than cover types on the ROW but populations were lowest in grass cover type. Small mammal diversity would be expected to be greater on the ROW with heterogeneous vegetative structure compared with the more homogeneous forest (after Anthony et al. 1981). One of the most important cover types to small mammals, e.g., forb-grass, on the ROW was the result of integrated vegetation management in the wire zone of a mowing plus herbicide unit, whereas the cane thicket cover type and the short shrub cover type were created by integrated vegetation management in wire zones of basal low-volume spray units (Yahner and Hutnik 2004). In particular, forb-grass was an important cover type for the meadow vole, which is a grass- land specialist (Grant 1971). Number of mammals captured varied between years with none found earlier in the year (May to June) in 2004, but 23 individuals were captured in these 2 months in 2005 (Table 1). These data attest to the value of conducting a study on flora and fauna for more than 1 year. Small mammals on the ROW increased in numbers subsequent to May (June through early November) in both years combined; small mammal abundances tend to increase from spring through autumn (Yahner 1983; Merritt 1987). The relative lack of mammals on the ROW and in the forest in May of both years is not surprising based on other studies (e.g., Beer 1961; Yahner 1983); in spring, for in- stance, abundance of small mammals is low, and movements by individuals probably are reduced. As the year progressed, reproduction and food resources increased, thereby resulting in more mammals found on the ROW. In August, in particu- lar, black chokeberry (Aronia melanocarpa), low-sweet blue- berry (Vaccinium angustifolium), and common blackberry were fruiting, which likely accounted for relatively large numbers of captures in this month on the ROW. Acknowledgments. Cooperators were Asplundh Tree Expert Co., Dow AgroSciences, FirstEnergy, and the Pennsylvania Game Com- Species White-footed mouse Meadow vole White-footed mouse Deer mouse White-footed mouse Meadow vole White-footed mouse 2004 3 0 4 1 0 1 0 6 37 2005 1 (1) 1 4 2 1 1 1 8 84 Total 4 1 8 3 1 2 1 8 121
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