Arboriculture & Urban Forestry 33(6): November 2007 Arboriculture & Urban Forestry 2007. 33(6):433–434. 433 Research Note Populations of Small Mammals on an Electric Transmission Line Area in Southeastern Pennsylvania, U.S. Richard H. Yahner and Richard T. Yahner The Green Lane Research and Demonstration Project has had three objectives since 1987: to determine the effectiveness of mechanical and herbicidal maintenance treatments on control of undesirable trees, development of tree-resistant plant cover types, and wildlife and species of high public interest (Yahner and Hutnik 2005). The wire-border zone method of vegeta- tion management was implemented on the electrical trans- mission line area (hereafter, right of way [ROW]) in 1987 (Yahner and Hutnik 2004, 2005), producing a tree-resistant forb–shrub–grass cover type in wire zones and a tall shrub cover type in border zones. Small mammals are important wildlife species by consum- ing tree seeds (Bramble et al. 1992), thereby reducing inva- sion of undesirable tree species on a ROW (Yahner et al. 2007). Small mammals also serve as prey for a variety of predators (Merritt 1987). In a previous study conducted in 1989 through 1990 (Bramble et al. 1992) and 2004 through 2005 (Yahner et al. 2007), at least seven species of small mammals were noted on the State Game Lands (SGL) 33 ROW in Center County, Pennsylvania, U.S.; long-term stud- ies of small mammals on a ROW are virtually nonexistent. Our objectives were to determine relative abundance and spe- cies richness (number of species) in four cover types along the ROW, resulting from herbicidal and mechanical mainte- nance of the vegetation, and in the adjacent forest. STUDY AREA AND METHODS Treatments on the ROW consisted of two units each of hand- cut, mowing, mowing plus herbicide, stem–foliage spray, and foliage spray. Five cover types were selected for study: ad- jacent forest (serving as a reference), tree sprout, shrub, shrub–forb, and grass. Major trees in forest cover type in- cluded red maple (Acer rubrum), white ash (Fraxinus ameri- cana), hickory (Carya spp.), and black cherry (Prunus se- rotina). Tree sprout was in the wire zone of a handcut unit; stumps were primarily white ash, and other plants included multiflora rose (Rosa multiflora), Japanese honeysuckle (Lonicera japonica), blackberry (Rubus allegheniensis), poi- son ivy (Toxicodendron radicans), goldenrod (Solidago spp.), and grass (Panicum spp.). Shrub was in the border zone of a mowing plus herbicide unit; principal shrubs were Japanese honeysuckle, blackberry, dewberry (R. hispidus), and poison ivy. Shrub–forb was well developed in the wire zone of a stem–foliage unit; vegetation consisted principally of dew- berry, Japanese honeysuckle, blackberry, goldenrod, and grass. Grass (mainly fall panic grass [Panicum spp.]) was in wire zones, with some common sow-thistle (Sonchus olera- ceus) and mile-a-minute (Polygonum perfoliatum). Mammals were surveyed monthly (May through Novem- ber 2005, May through October 2006, by placing six metal live traps ina2×3 grid in a 10 × 15 m (33 × 49.5 ft) area per cover type (after Yahner 1988). Cotton was used as bed- ding, and a small amount of peanut butter was put in each trap as bait just before dusk. Traps were checked on two consecu- tive mornings. Number of individuals trapped per species, date of capture, and location of capture relative to cover types were noted for each survey (Smith and Vrieze 1979; Yahner 1983). Sex and age (if known), reproductive condition, and individual identification (e.g., ear tag or toe clip) were re- corded (Rose and Dueser 1980). Because vegetative was sparse in the grass cover type each year, traps in this type were not set until August. Also, in September 2006, trapping was not conducted because of heavy rains caused by hurricane conditions. Small mammals were sampled a total of 342 trap nights (TN) in 2005 and 276 TN in 2006. RESULTS AND DISCUSSION Thirty-one small mammals (27 white-footed mice, Peromys- cus leucopus; three northern short-tailed shrews, Blarina brevicauda; one meadow vole, Microtus pennsylvanicus) were noted in 2005 and 2006. This included 19 in 2005 and 12 in 2006, which attests to the value of conducting a study on fauna for more than 1 year. The number of individuals noted at the Green Lane ROW and adjacent forest was much lower than 121 individuals (eight species) trapped at the SGL 33 area in 2004 and 2005. The capture rate was 5.2 individu- als/100 TN in both years combined in the current study. This ©2007 International Society of Arboriculture
November 2007
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