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The ecology of Myotis leibii (eastern small-footed myotis) remains largely unclear, including its foraging behavior. During fall, cavernicolous bats must accumulate enough fat reserves to sustain them during winter hibernation. We examined the food habits of eastern small-footed myotis captured at abandoned coal mines at New River Gorge National River in West Virginia during fall 2005. Based on fecal samples from 44 bats, we found that eastern small-footed myotis diets were diverse, containing 9 families within 7 orders of insects. Lepidoptera were consumed by all but one bat and represented the largest average percent volume among insect orders. This study elucidates an important component of the foraging ecology of this rare bat species.
We examined the response of small-mammal communities to human disturbance along a gradient from wilderness to managed forest to rural residential development in the Adirondack Park of northern New York. Our objectives were to determine if small-mammal community composition and structure differed among sites along a gradient of human impact and to relate changes in small-mammal community composition to habitat changes along the gradient. We sampled small mammals with track tubes on 10 replicates each of old growth, managed forest, and areas of residential development in the central Adirondacks. We estimated differences in species composition, abundance, diversity, evenness, and community structure, and identified habitat variables associated with differences in these measures. We used canonical correspondence analysis (CCA) to examine the relationship between patterns in small-mammal community composition and sampled habitat variables. Some small-mammal species demonstrated a numerical response to increasing human impact on the landscape, with abundance of total small mammals, eastern chipmunk, and Sorex species highest in old growth and declining in managed forests and areas of residential development. Differences among management types were reflected more strongly in total abundance and community structure than through indices of richness and diversity, which did not differ among management types. Canonical correspondence analysis revealed that 32% of the variability in the small-mammal community could be explained by habitat characteristics and that variables describing availability of coarse woody debris, as well as presence of shrubs in the understory, may create conditions favorable to many small-mammal species in these habitats.
The habitat use and activity range of Lampropeltis getula getula (Eastern Kingsnake) in the New Jersey Pine Barrens were studied from 1996–1998. Five male and four non-gravid female Eastern Kingsnakes were routinely radiotracked during daylight hours during one or two active seasons. Habitat and climatic conditions at snake locations were characterized using 9 climatic and 14 structural habitat features. Multivariate statistical comparisons with randomly selected locations indicated that Eastern Kingsnakes use available habitat in a non-random fashion with respect to microhabitat features (Wilks' lambda = 0.511; df = 28, 1066; P < 0.01). Eastern Kingsnakes preferred sites with thick leaf litter and dense shrub-layer foliage. They used a broad range of macrohabitats that spanned both wetland and pine-dominated upland areas. Moist areas were used for hibernation. Snakes exhibited a largely fossorial lifestyle, spending a great proportion of their time concealed under the cover of soil and/or leaf litter (79% of observations). Climatic conditions at selected sites did not differ between males and females. Analysis of movements revealed an affinity for specific locations within their established activity ranges. Males and females did not differ with respect to their activity ranges or measured movement patterns (e.g., mean distance traveled/day, total distance moved, range length).
Streambank fencing is increasingly used to exclude livestock from riparian corridors and to enhance biological communities. Our study examined vegetative change and avian-community use of recently fenced agricultural habitat. We conducted strip-transect surveys to census bird communities, line-transect and plot surveys to assess vegetation, and intensive nest monitoring to gauge use and reproductive success across 12 fenced riparian sites in southwestern Pennsylvania. Selected sites varied in age from 3 to 8 years since fencing and averaged 21 m in width. We found avian use was significantly greater in spring than in fall across our fenced sites. We determined that canopy cover, shrub cover, and herbaceous ground cover could predict various attributes of the avian community present within the fenced riparian areas. Our results also suggest that the avian community has greater species richness within sites containing greater habitat complexity, and that these sites are important breeding and nesting areas. Among the 145 nests monitored, 38% successfully fledged young. We found no differences in distance to corridor edge between successful nests and nests that failed. Our study confirms that riparian renovation efforts do have conservation value for both migratory and resident birds.
Weekly aerial surveys were conducted in central Labrador during the spring staging period (27 April to 29 May, 2000), and the relative abundance of waterfowl was documented. Anas rupribes (American Black Duck) and Bucephala clangula (Common Goldeneye) were among the first species to arrive, while peak waterfowl diversity occurred on the latest survey date. Overall, Branta canadensis (Canada Geese) were the most abundant species, followed by American Black Duck and Anas crecca (Green-winged Teal). As expected, the relative abundance of these species varied by date and region. By the time of the last survey on 29 May, average flock size had decreased for most species, most likely corresponding with the start of breeding and nest initiation. Our findings could be useful as baseline information for future studies of climate change, may have implications for the management of the aboriginal spring hunt, and also might be used to mitigate the effects of military flying activity.
Recent work on exotic species in island ecosystems has revealed that many exotic woody plants are capable of dominating forests in which they occur, substantially altering forest structure and nutrient cycling. In mainland forests, however, few empirical examples of exotic dominance exist. The invasive shrub Rhamnus cathartica L. (common buckthorn) is reported to infest temperate forest understories in North America and displace native species, but its degree of dominance has been described only anecdotally. We investigated the extent to which common buckthorn can dominate forest ecosystems, and found strong evidence for monotypic dominance in several mesic and wet sites in southern Wisconsin. Among eight forest sites where common buckthorn was dominant, its mean relative density and basal area was 81% and 45%, respectively. Compared to eight native-dominated sites on similar soils, common buckthorn dominance fundamentally altered forest structure: total woody stem density at Rhamnus-dominated sites was more than twice that of native-dominated sites (two-way ANOVA; P < 0.05, n = 16), but total basal area did not differ significantly (P > 0.3). When considering dominance by size class within only the eight Rhamnus-dominated sites, common buckthorn genets were more abundant than native genets at 5-cm size classes up to and including 20–25 cm diameter at breast height, evidence that common buckthorn dominance can extend well beyond understory size classes. Within Rhamnus-dominated sites, mean relative density and basal area for common buckthorn exceed that reported for four other woody invaders found in the northeastern US, and thus we suggest that common buckthorn is a particularly successful invasive species in eastern temperate deciduous forests of North America and is capable of acting as an ecosystem dominant.
During 1998–2000 and 2002–2004, field surveys were conducted within the Moosehorn National Wildlife Refuge, located in northeastern Maine, to determine if ozone-induced symptoms occurred on refuge vegetation. Foliar symptoms were observed on ozone-sensitive bioindicators during each survey year, but the incidence (percentage) of plants exhibiting symptoms was generally low and varied among species and years. Refuge plants that exhibited symptoms included Fraxinus spp. (ash), Populus spp. (aspen), Corylus cornuta (beaked hazelnut), Prunus serotina (black cherry), Prunus pensylvanica (pin cherry), Apocynum androsaemifolium (spreading dogbane), and a viburnum tentatively identified as Viburnum nudum var. cassinoides (withe-rod). Data from the nearest US EPA ozone-monitoring site, located 113 km southwest of the refuge in Acadia National Park, ME, revealed that ambient SUM60 ozone levels during survey years ranged from approximately 17,900 ppb-hrs in 2000 to more than 40,000 ppb-hrs in 1998. Therefore, the threshold level of SUM60 ozone capable of inducing symptoms on sensitive vegetation within this refuge and Class-I Wilderness area is less than 18,000 ppb-hrs, and may be as low as 10,000 ppb-hrs. The results of these surveys can be used by the US Fish and Wildlife Service when making air-quality management decisions, including those related to the review of Prevention of Significant Deterioration permits, and might serve as input into formulating more stringent National Ambient Air Quality Standards for ozone.
Annual field surveys were conducted from 1999–2004 within the Seney National Wildlife Refuge in northern Michigan to determine if ambient ozone levels at this remote location were great enough to injure refuge vegetation. Ozone injury was observed on sensitive bioindicator plants during each survey year; however, the incidence (percentage) of plants exhibiting symptoms was low and varied among species and years. Ozone-induced symptoms occurred on Sambucus canadensis (American elder), Prunus serotina (black cherry), Asclepias syriaca (common milkweed), and Apocynum androsaemifolium (spreading dogbane). The most sensitive species was spreading dogbane. In addition, ozone injury was observed on a vibur-num species, tentatively identified as Viburnum nudum var. cassinoides (withe-rod). Ambient ozone has been monitored since 2002 at an EPA monitoring site within the refuge. Cumulative SUM60 ozone levels (ppb-hrs) by the end of August for each survey year were greatest in 2003, followed by 2002, and least in 2004. The annual incidence of ozone injury for the 3 years was not directly related to level of ambient ozone, but was likely confounded by environmental factors such as drought. Based on the 2004 survey, the threshold level of SUM60 ozone needed to induce visible symptoms on sensitive vegetation in this remote refuge is close to 5000 ppb-hrs.
We describe the mite fauna inhabiting the canopies of remnant old-growth Acer saccharum (sugar maple) trees in northern hardwood stands under different silvicultural treatments in the Adirondack Mountains. We also compare mites on different arboreal substrates, including bare bark, the crustose lichen Pertusaria velata, and three foliose lichens: Flavoparmelia caperata, Parmelia squarrosa, and Punctelia rudecta. A total of 877 individual mites were collected representing 25 oribatid mite species, at least three of which are undescribed, and nine non-oribatid mite families. Mite abundance was sevenfold greater in Punctelia rudecta than on bare bark, and communities differed among bark, crustose lichen, and foliose lichens, but not among the different species of foliose lichens. Trees in old growth and reserve shelterwood stands supported different mite communities.
We introduce an analysis method to demonstrate correlation between biota and the physical habitats that they occupy. Using the same calculations as does Nei's genetic distance index, this method builds independent dissimilarity matrices for both habitat and fauna, which can then be compared in a common statistical framework. An important advantage of this method is that only frequency data are necessary to perform the analysis. We demonstrate the utility of this method using fish community and habitat data from the Eightmile and Pomperaug rivers in Connecticut. In both cases, there is a significant correlation between biota and habitat. Not only is ecological dissimilarity analysis a useful technique for testing community-to-habitat correlation, it is also an excellent tool for communicating this information to the many non-scientists who shape conservation policy.
Etheostoma maculatum (Spotted Darter) has a disjunct distribution within the Ohio River drainage. Researchers have generalized Spotted Darter habitat as large rocks in swift riffles. In West Virginia, Spotted Darters are known to occur only in the middle section of the Elk River system. Information on habitat use is lacking. Through direct observation (snorkeling), we examined microhabitat use of Spotted Darters in riffle and glide habitats at three sites in the Elk River. Spotted darters in the Elk River were observed primarily in glide habitats near large rocks and in moderate current velocities. In the Elk River, this species is a benthic-habitat specialist, making it highly vulnerable to habitat alterations such as sedimentation and substrate embeddedness. Given its habitat use and restricted distribution, further ecological studies are needed for conservation and management of the Spotted Darter population in the Elk River.
We completed laboratory-feeding studies that demonstrated preference of the headwater stream fishes Gambusia holbrooki (Mosquitofish) and Clinostomus funduloides (Rosyside Dace) for smaller Gammarus pseudolimnaeus (amphipods) over larger ones. We also submerged oak leaf-litter bags in sections of streams with and without these fish predators. After three weeks, the mean number ± s.e. of amphipods per litter bag in streams with fish was significantly lower (289 ± 50 vs. 978 ± 122) and the average size of amphipods was significantly larger (13.9 ± 0.1 mg vs. 8.1 ± 0.1 mg), relative to streams without fish. The quantity and quality of leaf litter, however, were not significantly different. Top-down predation may have altered the population structure of stream-dwelling amphipods, but did not change leaf decomposition over the time of the study.
Previous freshwater mussel surveys (1915–1997) at sites in the upper North Fork Holston River watershed upstream of Saltville, VA, documented 21 species. To assess current status of the fauna, approximately 363 survey hours were spent qualitatively sampling 44 sites in a 77-km reach of the upper river between Saltville and Ceres during 2000–2004. Thirteen species of live freshwater mussels were collected. Species richness appears to have declined only slightly over the last 100 years in this reach of river. However, declines in abundance are now evident in a 6.4-km reach immediately upstream of Saltville. A die-off of federally endangered Fusconaia cor (shiny pigtoe) and candidate species Lexingtonia dolabelloides (slabside pearlymussel) was documented in the upper river during 1999–2002, but the cause was not identified.
Little information exists on macroinvertebrate community composition in small, micro-tidal, Ruppia maritima (widgeon grass)-dominated Maine estuaries. Qualitative and quantitative assessments of the macroinvertebrate fauna of widgeon grass beds in Northeast Creek estuary (Acadia National Park, ME) are presented here. The community was dominated by euryhaline freshwater invertebrates including midge larvae (Chironomidae: Dicrotendipes, Cricotopus, Chironomus), oligochaetes, damselfly larvae (Coenagrionidae: Enallagma), amphipods (Gammaridae: Gammarus), gastropods (Hydrobiidae: Hydrobia), ostracods (Cytheridae: Cyprideis), and water boatmen (Corixidae: Trichocorixa). Macroinvertebrate abundances at the sampled sites were 35,100 individuals/m2 in both August and September, and 22,200 individuals/m2 in October. This study provides baseline faunal-community data that can be used in future monitoring studies.
We document the discovery of Campostoma anomalum (Central Stoneroller) in the tidal mouth of the Poestenkill, a Hudson River tributary in Troy, NY. This is the first record of the species from a tidal habitat and is a range extension of approximately 68 km downstream from the Mohawk River.
Procambarus (Ortmannicus) acutus (White River crayfish) was added to West Virginia's decapod crustacean fauna on 26 February, 2004, and this finding was the first record of the genus Procambarus in West Virginia. Six P. (O.) acutus (4 form-I males, 2 females) were collected in traps from a large vernal pool system 1.2 km east of Point Pleasant, Mason County. Several additional specimens were collected from this site during the spring of 2004, with an additional 3 populations discovered in the spring of 2005. White River Crayfish were collected in ephemeral pools, marshes, and roadside ditches. White River Crayfish were found in ephemeral systems only, and appear to have shifted aspects of their typical ecology to suit these systems in West Virginia. White River Crayfish distribution in West Virginia appears to be limited to the pre-glacial Marietta River Valley, and results suggest that it is a native species in West Virginia.
A study of the hibernating bats present in select western Massachusetts hibernacula was initiated during the winter of 2005–2006. During the surveys, five state-threatened Myotis leibii (eastern small-footed bats) were observed within one hibernaculum (Bat's Den Cave). These five individuals were the first eastern small-footed bats observed in Massachusetts since 1999, and represent a new county distribution record (Berkshire County).