Small Mammal Survey of the Nulhegan Basin Division of the Silvio 0. Conte NFWR and the State of Vermont's West Mountain Wildlife Management Area, Essex County Vermont • Final Report March 15, 2001 C. William Kilpatrick Department of Biology University of Vermont Burlington, Vermont 05405-0086 A total of 19 species of small mammals were documented from the Nulhegan Basin Division of the Silvio 0. Conte National Fish and Wildlife Refuge (NFWR) and the West Mountain Wildlife Management Area Seventeen of these species had previously been documented from Essex County, but specimens of the little brown bat (Jr{yotis lucifugu.s) and the northern long-eared bat (M septentrionalis) represent new records for this county. Although no threatened or endangered species were found in this survey, specimens of two rare species were captured including a water shrew (Sorex palustris) and yellow-nosed voles (Microtus chrotorrhinus). Population densities were relatively low as reflected in a mean trap success of 7 %, and the number of captures of two species, the short-tailed shrew (Blarina brevicauda) and the deer mouse (Peromyscus maniculatus), were noticeably low. Low population densities were observed in northern hardwood forests, a lowland spruce-fir forest, a black spruce/dwarf shrub bog, and most clear-cuts, whereas the high population densities were found along talus slopes, in a mixed hardwood forest with some • rock ledges, and in a black spruce swamp. The highest species diversity was found in a montane yellow birch-red spruce forest, a black spruce swamp, a beaver/sedge meadow, and a talus slope within a mixed forest. The lowest species diversities were found in northern hardwood forests, a black spruce/dwarf shrub bog, and most clear-cuts. · Introduction Two portions of land in Essex County, Vermont, recently purchased from the Champion Paper Company through the Vermont Land Trust have been designated as the Nulhegan Basin Division of the Silvio 0. Conte National Fish and Wildlife Refuge (NFWR) and the West Mountain Wildlife Management Area. Much of this area of Northern Highlands (Northeast Kingdom) is a moist, boggy, ·swampy area ofboreal forest (Johnson, 1998) that includes a number of low mountains, less than 3000 feet in elevation. The Nulhegan Basin of the Conte NFWR, administered by the U.S. Fish and Wildlife Service, consists of26,000 acres in Lewis and parts of Ferdinand and Bloomfield townships north of Route 105. This area includes the drainage of the three major branches of the Nulhegan River and a number of bogs. The West Mountain Wildlife Management Area (WMA), administered by the Vermont Agency of Natural.Resources, consists of • 1 > i 22,100 acres in Ferdinand, Brunswick, and Maidstone townships south of Route 105. This area includes a number of ponds and bogs along Paul and Wheeler Streams. Thirty-six species of small mammals (i.e., weighing less than 500 g) are known from Vermont and include one species listed as endangered (Indiana bat), one listed as threatened (small-footed bat), and eight species considered rare (long-tailed shrew, pygmy shrew, silver-haired bat, red bat, hoary bat, southern bog lemming, rock vole and pine vole). Those species listed above as rare are known from fewer than 5 0 specimens collected from Vermont. Although little survey work for mammals has been reported to date from Essex County, 21 of the 36 species of small mammals known from the state have been documented from this county (Kirk, 1916, Osgood, 1938a; G9din, 1977; Chipman, 1994). The objective of this study was to survey the small mammal diversity in the newly established Nulhegan Basin Division of the Silvio 0. Conte National Fish and Wildlife Refuge (NFWR) and the West Mounta~ WMA. This survey was conducted by surveying wetland and upland sites that were characteristic of natural communities of this region including northern hardwood forests, red spruce-northern hardwood forests, black spruce swamps, dwarf shrub bogs, alluvial shrub bogs, and beaver meadows. In addition, specific habitats (hot spots), including swift-flowing streams, talus slopes and clear-cuts, associated with the occurrence of rare species of small mammals were surveyed. Bat activity and diversity was investigated by use of mist nets and acoustical monitoring. Materials and Methods • Between 7 June and 15 October 2000 small mammals were collected with Sherman live traps and Museum Special snap traps from 19 sites (Appendix I). Traps were baited with either rolled oats or peanut butter and were set in the evening and checked in the early morning. Most sites were trapped for three consecutive nights with 60 to 100 traps per night. Traps were set in lines with the traps spaced about 20 feet apart. The upland sites sampled included two northern hardwood forests, three red spruce-northern hardwood forests, a lowland spruce-fir forest, and a montane yellow birch-red spruce forest. Other sites sampled included a black spruce swamp, a black spruce/dwarf shrub bog, two dwarf shrub bogs, an alluvial shrub swamp, a beaver meadow/sedge marsh, four boulder fields (talus slopes) with varying degrees of canopy and slope, and three clear-cut sites in early successional stages. Additional trapping methods were employed in an attempt to obtain additional specimens of shrews. For water shrews, thirty Museum Special snap traps baited with peanut butter were tied to vegetation and set along the edge of swift -flowing streams at five sites. For other shrews, 10 pit traps set 5 feet apart with a connecting drift fence were established at six sites including a northern hardwood forest, a black spruce/dwarf shrub bog, two dwarf shrub bogs, an alluvial shrub swamp and a: clear-cut. • 2 The presence of bats was surveyed by the placement of mist nets across logging roads, trails and streams and by acoustical surveys using the Anabat II receivers. Bats were captured using 38 mm mesh, 2-ply-50 denier black nylon (Avinet) mist nets of 6 m and 12 m lengths. Mist nets were oriented horizontally • over streams at six sites and along logging roads at four sites for a total 30 net nights. In addition, an acoustical survey was conducted on 18 nights either near the area being netted or at areas where netting was not possible. The acoustical surveys were conducted using :frequency-division (Anabat II) detectors to evaluate general bat activity and to compare species detected with the acoustical survey with species captured in the field. · In order to assess habitat diversity not solely based on species richness (number of species) but also on the abundance of each species (species eveness) the following diversity indices, which account for heterogeneity in species eveness, were calculated. Simpson's index (Krebs, 1989) was calculated by: . D=LJJP where D is Simpson's index arid pi is the proportion of species i in the community. This diversity index predicts the probability of collecting two organisms that are the same species. More commonly used is its complement, 1 - D, which is the probability of collecting two organisms that are different species. The Shannon-Wiener index is derived from information theory and was calculated by the following: · H' = -Ilpi)(IogiJJi) where H' is the Shannon-Wiener index of species diversity and pi is the proportion of the sample comprised of the ith species. This index is a measure of the amount of uncertainty in predicting the species of an individual chosen at • random. Voucher specimens ofrepresentative specimens (Table 1) of all species collected were prepared as museum skins and skulls and are deposited in the Zadock Thompson Natural History Collections of the University of Vermont. Tissues and ectoparasites were collected from all specimens prepared as vouchers. For all specimens of the genus Peromyscus captured both salivary and blood samples were collected. The blood samples have been sent to the CDC for testing for hantavirus and Lyme disease. Salivary samples were used to identify mice of the genus Peromyscus unambiguously to species using the genetic markers at the salivary amylase locus following the methods of Aquadro and Patton (1980) with the modifications of Kilpatrick et al. (1994). Results A total of 19 species of small mammals (Table 1) were documented from the Conte Refuge and the West Mountain WMA of Essex County, Vermont. In addition, nine species oflarger mammals were observed during the survey including: woodchucks (Marmota monax), beavers (Castor canadensis), • 3 TABLE 1.--Small mammals collected in a survey of the Conte Refuge and the West Mountain Wildlife Management Area of Essex County, Vermont. Taxon Number Captured Voucher Specimens Insectivora Talpidae Parascalops breweri 2 2 Soricidae Sorex cinereus 11 9 Sorex fumeus 4 4 Sorex palustris 1 1 Blarina brevicauda 4 4 Chiroptera V esp.ertilionidae Myotis lucifugus 10 2 Myotis septentrionalis 24 2 Rodentia Sciuridae Tamias striatus 4 2 Tamiasciurus hudsonicus 2 1 Glaucomys sabrinus 1 1 Muridae (Sigmodontinae) Peromyscus maniculatus 41 27 Peromyscus leucopus 1 1 (Arvicolinae) Clethrionomys gapperi 95 57 Microtus pennsylvanicus 13 10 Microtus chrotorrhinus 2 2 Zapodidae Zapus hudsonius 26 16 Napaeozapus insignis 63 28 Carnivora Mustelidae Mustela erminea 3 2 Mustela frenata 2 1 TOTAL 309 172 4 snowshoe hares (Lepus americanus), coyotes (Canis latrans), red foxes (Vulpes vulpes), black bears (Ursus americanus), stripped skunks (Mephitis mephitis), white-tailed deer (Odocoileus virginianus) and moose (Alces alces). • Small Mammal Diversity A total of 4305 trap nights were spent surveying 19 sites with an average trap success of7.0%. The effort of sampling at each site ranged from 70 to 392 trap nights (Tables 2-4) and the success varied from 0.8 in a lowland spruce forest to 21.6% among the large boulders of an old stream bed within a mixed forest. The effect of the time of year a habitat was sampled on both trap success and species diversity is shown in Figure 1.