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Neotoma magister (Allegheny Woodrat) is a medium-sized rodent associated with rock outcrops, talus slopes, caves, cliffs, and boulder fields in the central and southern Appalachians and Allegheny Plateau physiographic provinces. It is currently classified as a G3G4 species and is considered threatened, endangered, or a species of concern in almost every state in which it occurs. As part of a 12-yr study on the status and distribution of the Allegheny Woodrat in Virginia, we collected data on woodrat ecology and population demographics. Herein, we investigate the relationship between acorn production and an index of woodrat abundance for several woodrat populations in Virginia. Woodrat population size was estimated using the Lincoln-Peterson index. Acorn mast surveys were conducted by the Virginia Department of Game and Inland Fisheries from 1989 to 2002 to index mast abundance. Woodrat population estimates were positively correlated (P < 0.05) to the previous year's mast crop index at 2 of 4 monitoring sites. Woodrat populations were not correlated to the mast crop two years prior. Acorn production alone does not appear to account for decline in woodrat populations. Range-wide declines in Allegheny Woodrats are likely due to a combination of local and landscape factors, but forest managers should consider acorn production when writing management prescriptions if woodrats are present within the management unit.
To determine habitat characteristics that influence Sciurus niger (Eastern Fox Squirrel) abundance and distribution within a suburban/urban landscape in the midwestern United States, I documented the density and placement of fox squirrel leaf nests in 20 woodlots in the Indianapolis metropolitan area, Marion County, IN. The woodlots varied in size (0.94 to 19.5 ha), approximate age, shape, and degree of isolation from other woodlots and suitable squirrel habitat in the surrounding area. Only 8.0% of nests were located in a tree with another nest, and nests were randomly distributed in all but one woodlot, where they were uniformly dispersed. Nest density was not significantly related to woodlot size, approximate age, shape, or degree of isolation. Fox squirrel leaf nests were not found in greater densities along the edge of each woodlot, contrary to previous reports. My results suggest that the distribution patterns of fox squirrels within suburban/urban landscapes are similar to patterns within landscapes fragmented by agriculture.
The short-term negative impacts on Lepus americanus (Snowshoe Hare) of logging activities in boreal forest are widely recognized, and conservation efforts are being taken now in designing residual forest stands to maintain use of logged landscapes by hares. This study evaluated the effectiveness of three types of residual stands in maintaining hares during the high phase of hare density cycle in Picea mariana (Black Spruce) forest of eastern Canada. Residual forest stands sampled were upland strips (60 m wide, 250–950 m long, mesic conditions), riparian strips (100 m wide, 250–950 m long, along a permanent stream), and residual blocks (200–300 m wide, 20–50 ha). Control stands were undisturbed forest. All stands were considered mature (56–97 years old). Pellet and browse surveys were conducted during spring 1998 and 1999. Hare abundance indices were significantly lower (1999), or tended to be lower (1998), in strips than in blocks, although habitat composition and structure of the treatments did not differ from control stands. Pellet presence was positively related to vertical cover. In 1998, foraging activity (browsing) was significantly higher in control and block landscapes than in strip landscapes; browsing was positively related to availability of ericaceous and deciduous twigs. In 1998, twenty Snowshoe Hares were radio-tracked in residual stands to monitor their summer home ranges, fidelity to capture sites and to type of residual stand, use of clear-cuts and uncut forest, and daily movements. There was a clear trend towards lower fidelity to strips than to blocks, and summer home ranges and daily movements (>330 m) tended to be larger in strips compared to those in blocks. Our study suggests that up to 5 years after logging, residual forest blocks appeared to be more suitable habitat in summer for Snowshoe Hare than were 60-m-wide strips.
Intra- and inter-specific variation in ectoparasite prevalence was characterized by collecting and identifying parasites on Myotis septentrionalis (Northern Long-eared Bat) and Myotis lucifugus (Little Brown Bat) returning to a large hibernaculum during the autumn migratory and reproductive swarming event in Nova Scotia, Canada. Unlike males, female bats in the region are colonial roosters during the summer, which may facilitate ectoparasite transfer. On bats captured at Hayes Cave, NS, there were at least four species of ectoparasites including Myodopsylla insignis (Siphonaptera: Ischnopsyllidae), Spinturnix americanus (Acarina: Spinturnicidae), Cimex adjunctus (Hemiptera: Cimicidae), and a larval Trombiculid mite, Leptotrombidium myotis (Acarina: Trombiculidae). Parasite prevalence was 30.6% and 27.8% for adult M. septentrionalis females and males, respectively, and 25.6% and 16.3% for adult female and male M. lucifugus, respectively. Myodopsylla insignis, S. americanus, C. adjunctus, and L. myotis all represent new host records on both bat species in Nova Scotia, while S. americanus and L. myotis are new species records for the province.
We discovered that spiders use seed heads of Sarracenia purpurea (Northern Pitcher Plant) for moulting, nesting, and rearing of young. These associations represent only a few of the diverse interactions between spiders and pitcher plants. During July–August 2001 at Acadia National Park, seed heads (n = 301) of S. purpurea from four bog-heaths yielded spiders (n = 685) of four families (Theridiidae, Dictynidae, Clubionidae, Salticidae), 10 genera, and at least 11 species. Two additional spider families (Gnaphosidae, Thomisidae) were represented by cast exuviae. Jumping spiders (Salticidae) were the chief occupants, comprising 80.0% of species and 99.1% of individuals. The salticid Tutelina similis was the most common inhabitant, accounting for 63.8% of the overall spider fauna in these microhabitats. Spider foraging-guild presence favored hunters (99.7%) over web spinners; juveniles outnumbered adults almost 15 to 1, and females outnumbered males 43 to 1. Frequencies of spider webbing and retreats in seed heads were greater than expected (G-test, α = 0.05); however, spider occupancy was less than expected. Seed heads with multiple-spider occupants were more frequent than those with single-spider occupants; conspecific associations were more frequent than heterospecific associations. No evidence was found that spiders preferred either closed or open seed heads. Other associated arthropods included parasitic mites, spider-egg parasitoids, and insects. The identified taxa represent the first records of spiders inhabiting seed heads of S. purpurea in Maine.
We investigated the distribution and abundance of Alliaria petiolata, an invasive biennial, with respect to historical land use, and examined environmental conditions to look for correlations with distribution patterns. Sixty currently forested plots in Cuyahoga Valley National Park, OH were chosen based on 1959 land use: agricultural (open) versus forested. Plots were analyzed for Garlic Mustard distribution, abundance, invasion area, and incursion distance. Garlic Mustard distribution did not vary with historical land use, but did vary significantly with distance from rivers and with elevation. Polygon area:perimeter values were also correlated with invasion. These results differ from studies done with Garlic Mustard in New England where historical land use appeared to be a larger factor in distribution. These results suggest the importance of landscape corridors in biological invasions and can be used to identify areas with greater potential for invasive species in this region.
Stream fish survey data were analyzed to describe patterns of fish distributions in wadeable streams (primarily 1st–4th order) in Connecticut. Species occurrence within the United States Geological Survey 8-digit hydrologic unit code watersheds were used to aggregate similar watersheds into stream fish faunal regions. Within each identified region, multivariate analyses were used to identify major fish assemblage types and associate stream habitat with assemblage types. The analyses revealed an eastern and western faunal region defined primarily by distribution of a few native species. Native species associated with the western watersheds were: Semotilus atromaculatus (Creek Chub), Exoglossum maxillingua (Cutlips Minnow), and Cottus cognatus (Slimy Sculpin). Native fishes associated with the eastern watersheds were: Erimyzon oblongus (Creek Chubsucker), Esox niger (Chain Pickerel), and Esox americanus (Redfin Pickerel). Inclusion of non-indigenous species in the analyses resulted in a similar east–west grouping of watersheds. Five and four assemblage types were identified in the eastern and western faunal regions, respectively. Both regions harbored 3 fluvial assemblages defined longitudinally from headwater streams to larger wadeable streams and a macro-habitat generalist assemblage inhabiting streams with proportionately more pool habitat, but taxonomic membership and indicator species rankings among assemblages were not necessarily identical between the regions. A distinct assemblage dominated by Redfin Pickerel was recognized only in the eastern region. Streams in the western region were generally higher in elevation and colder in water temperature. The discovery and description of eastern and western fish faunal regions and their fish assemblage types will be useful in stratifying the biological monitoring of streams and other aquatic resource management actions in Connecticut.
The concept of a lake as an isolated unit is a central theme in research and management of freshwater systems. Support is based on direct observations of lake communities. Studies undertaken in the last several decades lend tacit support because the methods used in both research and management often do not question the underlying notion that lake communities are essentially isolated. In a study of fish assemblages in interconnected lakes, we noted movement of tagged fish among lakes. We also found that species introduced to one lake were later captured in neighboring lakes. We found that fish species in lake assemblages did not differ from those in inlet and outlet stream assemblages; although relative abundance varied, species richness and composition did not. This finding suggests that fish assemblages in lakes are not isolated. Rather, immigration and emigration from streams and other lakes occurs. Although few individuals migrated to new lakes, any movement can affect population structure (e.g., through recolonization, gene flow) and management goals (e.g., spread of disease). Consequently, we suggest that methods commonly used to assess fish assemblages in lakes and the concept of the lake as a management unit may need to be reconsidered. Rather than be treated as isolated populations, fishes in lake communities may be better treated as a watershed-wide metapopulation.
Dreissena polymorpha (Zebra Mussel) is capable of attachment to a wide range of natural and man-made materials, but individuals tend to attach to hard, solid substrates. The effects of mesh substrates on Zebra Mussel attachment has not been studied. This study examined the attachment of adult Zebra Mussels to mesh substrates. Zebra Mussels >5 mm shell length were placed on trays constructed of mesh of different hole size and material, and a hard substrate (PVC) control. Their attachment choice was recorded after a 14-d period. The results indicated that Zebra Mussels do not tend to attach directly to mesh, and instead will move towards the closest hard substrate, usually another mussel. There was no significant difference between numbers of mussels attached to different mesh material types and mesh pore sizes. This study furthers our understanding of Zebra Mussel attachment and their preferences when attaching to substrata and has implications for fisheries biologists, aquarists, and others who use nets, mesh, or screens in fresh water.
The original Picea rubens (Red Spruce) forest in West Virginia covered approximately 1.5 million acres, most of which was eliminated between 1870 and 1920 by clear-cutting and conflagrations. The total range of Plethodon nettingi (Cheat Mountain Salamander) was confined within this Red Spruce forest. Fires burned the duff and soil to the bedrock in many places, thus eliminating salamander habitats. It is hypothesized that Cheat Mountain Salamanders were eradicated throughout much of their range, and only areas with large emergent rocks or boulder fields provided refugia where they survived.
Catharus bicknelli (Bicknell's Thrush) is a rare inhabitant of mountain forests in the northeastern United States and southeastern Canada. Conservation planners consider the species to be at risk, although evidence of population decline has thus far been localized or inconclusive. In order to assess the status of Bicknell's Thrush in the White Mountains of New Hampshire, we conducted point-count surveys on 40 forested, high-elevation routes from 1993 to 2003. Non-linear regression on aggregate counts revealed a 7% annual decline over this period (P < 0.1). We discuss possible threats to Bicknell's Thrush, including winter habitat loss, pollution of mountain ecosystems, climate change, and human intrusion during breeding. A range-wide monitoring program that incorporates new survey methods is needed to help identify limiting factors and reduce potential sources of error and bias. This study underscores the importance of efforts to monitor and conserve Bicknell's Thrush.
We observed the alert responses of Sciurus carolinensis (Eastern Gray Squirrel) to two different approach stimuli (human only and human with a leashed dog) in two suburban habitats differing in the level of human activity. Alert distance in the habitat with higher levels of human activity was significantly shorter than the alert distance in the habitat with lower levels of human activity. Overall, the alert distance did not differ between the approach by a human alone and the approach by a human with a dog; however, in the high human activity sites (but not the low human activity sites), the presence of the dog increased alert distance in the squirrels. In addition, squirrels tended to initially respond by running more in the high human activity sites, but the presence of the dog increased the number of squirrels whose initial responses were to not run. Our results suggest that Eastern Gray Squirrel antipredator behavior, at least in response to humans and human-associated animals, is influenced by the level of human activity in the surrounding habitat.
In 2006, we collected two Sorex dispar (Long-tailed Shrew) specimens from Mac-Donald Pond, NS, Canada, which is a range extension of this elusive species. Trapping data revealed significantly lower numbers of Myodes (= Clethrionomys) gapperi (Red-backed Vole) bycatch than expected based on previous studies. Red-backed Voles are the most common rodent found in Nova Scotia forests. Here we report an apparent population crash of Red-backed Voles in Nova Scotia, along with a closer examination of a Cape Breton Island population.
We document the spring 2007 die-off of 216 Tachycineta bicolor (Tree Swallow) in western New York due to a period of unseasonably warm temperatures followed immediately by a period of unseasonably cold temperatures. Dead swallows were collected from artificial nesting boxes, where they had roosted communally. A subsequent decline in nesting effort was detected during the following nesting season. Implications for future nest-box management are discussed.