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We compared breeding activity of Ambystoma maculatum (Spotted Salamander) and Rana sylvatica (Wood Frog) in artificial impoundments to patterns in natural wetlands over a three-year period in the Delaware Water Gap National Recreation Area. Rana sylvatica were 5.6 times more likely to use natural bodies of water for breeding than artificial impoundments, while A. maculatum were 2.7 times more likely to use natural bodies of water. Both species were approximately 9 times more likely to breed in fishless bodies of water than in waters with predatory fish. Ambystoma maculatum were 6 times more likely to breed in wetlands with more stable seasonal hydroperiods, while R. sylvatica were only 2 times more likely to do so. We conclude that the high likelihood of fish presence in impoundments was the primary explanation for why both species were less likely to use impoundments than natural wetlands, while the tendency of A. maculatum to avoid natural wetlands with shorter hydroperiods explained why differences in use between pond types was more pronounced for R. sylvatica.
We studied the diet of Desmognathus welteri (Black Mountain Salamander) and compared it with the diet of D. monticola (Seal Salamander) in sympatry, using stomach contents. The diets of the two species were 86.6% similar, with four of five top prey categories in common. The most numerically important prey items for both species were adult dipterans and coleopterans and winged hymenopterans. Desmognathus welteri consumed a larger percentage of aquatic prey. No salamander remains were found in the stomachs of either species, weakening the supposition that large desmognathines are significant predators on small ones. We suggest that the differences in diet are a result of differences in micro-habitat use and body size.
Composition of southern Appalachian forests are influenced by disturbance and topography. This study examined six stands in southwestern Virginia. Within each stand, a 0.3-ha plot was established, and all trees and saplings were measured and aged. Burned stands had lower densities of saplings and small trees, but appeared to have greater Quercus regeneration. Ice damage from the 1994 ice storm was most evident in Pinus strobus saplings. A stand on old coal-mine slag appeared to be experiencing a slower rate of succession than other sites. A variety of stand development patterns were observed, but one common pattern was that oak-hickory overstories had different species in their understory, which may indicate future changes in species composition.
Old-growth forests are currently identified as core components of regional conservation and forest-reserve planning efforts by agencies and organizations across the northeastern United States. Despite the importance of these ecosystems from an ecological and conservation standpoint, major questions remain concerning their actual extent, location, and configuration in many states. Here we report a substantially revised estimate for individual tracts and the total area of old-growth forests in Massachusetts based on analysis of historical documents and extensive field research and mapping. We estimate that the total area of old-growth in the state is 453 ha, in 33 stands that range from 1.2 to 80.9 ha in size. Over 80% of these forests occur in the Berkshire Hills and Taconic Mountains in the extreme western part of the state. These forests are structurally unique and contain some of the oldest documented Tsuga canadensis (hemlock) and Picea rubens (red spruce) in New England, as well as the second-oldest documented Betula lenta (black birch) in the country. Due to their relatively small size and isolated character, these areas are susceptible to human and natural disturbance and require protection, including substantial buffer areas. Old-growth stands will enhance the value and function of designated forest reserves and will gradually become surrounded by forests of increasingly similar structure and ecosystem characteristics.
Falcipennis canadensis (Spruce Grouse) are a habitat specialist of coniferous forest in North America and typically have large home ranges (≈ 25 ha, range = 22–75 ha). Although this species is sensitive to logging, few studies report abundance and population trends in relation to habitat loss and fragmentation. In early May of 1997 to 1999, we surveyed Spruce Grouse in 21 riparian and 27 upland residual forest strips (width = 51–132 m) located within six clear-cut landscapes (23–256 km2) of southcentral Québec, Canada. We also surveyed five control sites in uncut continuous forest surrounding one landscape. Contrary to our prediction that Spruce Grouse would not be observed from such narrow strips, they were detected in 24 of the 48 strips. Both types of strips had similar occurrence rates and abundance indices (2.01 ± 0.46 [SE] males/10 stations in riparian strips, 1.29 ± 0.35 males/10 stations in upland strips). Because of the age of adjacent cuts (mean = 4.2 years, range = 2–8 years), crowding of grouse that were present at logging time into forest strips does not adequately explain the numbers of Spruce Grouse in these structures. Therefore, we conclude that Spruce Grouse observed in forest strips have either immigrated from outside or were local recruits. Despite persistence of Spruce Grouse in residual forests of logged landscapes, we suggest a cautious approach to forest management since the species' long-term persistence could be jeopardized if residual forest strips are harvested.
Swainson's Warbler is among the forest-bird species of highest conservation concern in the eastern United States. Recent publications include conflicting accounts of the species' breeding status at the northern limit of its range on the Delmarva Peninsula in Maryland and Delaware. To clarify this ambiguity, we reviewed and compiled the peninsula's published locality records. Three conclusions are evident from our analysis: 1) despite reports to the contrary, Swainson's Warbler continues to persist in two disjunct areas within the Pocomoke River watershed: Great Cypress Swamp in Maryland and Delaware, and Hickory Point Swamp in Worcester County, MD; 2) sporadic breeding-season records suggest small scattered breeding sites in other parts of the watershed, especially in the upper Nassawango Creek in Wicomico County, MD; and 3) further effort is warranted to better identify and delineate regularly occurring breeding areas in unexplored areas of the Pocomoke and adjacent Nanticoke watersheds. Because the long-term viability of the peninsula's population is uncertain, we believe the species' current legal status as State Endangered in Maryland and Delaware remains warranted.
We report two observations of breeding dispersal by migratory songbirds, Dendroica caerulescens (Black-throated Blue Warbler) and D. fusca (Blackburnian Warbler), from their initial territory locations following timber harvest. Forty-eight birds of each species were captured and marked as part of a long-term study on warbler survival in the Greater Fundy Ecosystem, NB. None of the birds banded in unharvested patches were re-encountered in other patches. Maximum movement distances for the displaced Blackburnian Warbler and Black-throated Blue Warbler were 1.3 km and 2.9 km, respectively. These are the longest breeding-dispersal distances reported for these species. Our paper provides the first direct evidence that birds may move once their breeding site has been altered due to timber harvesting. Potential conservation implications are discussed.
The second documented larval habitat for the northern caddisfly, Phanocelia canadensis (Trichoptera: Limnephilidae), is far south of the center of the species' range in Canada. We collected larvae of this rarely found species from two small, kettle hole wetlands on Cape Cod, MA. The life cycle and behavior are similar to the New Brunswick population studied by Fairchild and Wiggins (1989). Habitat characteristics distinguishing wetlands where P. canadensis occurs include dominance by Sphagnum sp., shrub cover, and low pH. Narrow habitat requirements, summer dormancy, and late adult emergence may limit this species' appearance in collections. Conservation planning and searches for additional populations may be aided by improved understanding of this species' preferred habitat.
Exotic populations of Phragmites australis (common reed) are now present in southern New England wetland habitats where native populations were once abundant. We surveyed Rhode Island to determine the distribution of native and exotic P. australis, and used this information to build a publicly accessible Geographic Information System (GIS) database. All P. australis populations sampled on the mainland were exotic. We only found native populations growing throughout a network of tidal marshes and ponds on Block Island, and several of these populations are being overrun by expanding exotic populations. The GIS database from this survey can be expanded to other regions, and can be used for the conservation of the native subspecies and for ensuring that control efforts target only exotic populations.
Native and exotic haplotypes of Phragmites australis show differential susceptibility to herbivores, but the mechanisms behind these differences are not known. Endophytic fungi are common in the grass family and confer resistance against insects through the production of toxic chemicals. We used both a common endophyte-staining technique and interference contrast microscopy to analyze leaf sheaths of native and exotic P. australis haplotypes from several populations in the northeastern United States to determine if the various haplotypes were infected with endophytes. No endophytes were found in any of the native and exotic haplotypes using procedures that consistently detected endophytes in infected rye grass.
A qualitative mussel survey was performed on Muddy Creek, a tributary to French Creek in Crawford County, PA, within the boundaries of the Erie National Wildlife Refuge. Riffle-run-pool sequences were sampled at 20 locations in the study area using visual and tactile timed-search techniques. Live specimens represented by 22 species were encountered at a rate of 54 individuals per person-hour and included the federally-endangered Pleurobema clava (clubshell) and Epioblasma torulosa rangiana (northern riffleshell) as well as four Pennsylvania state-imperiled species. Evidence of recruitment in the clubshell population was found in excavated quadrats and by hand-collecting. Brillouin diversity indices ranged from 0.35–2.88 over the study area, with a mean (SD) of 1.67 (0.59). The three most abundant species were Actinonaias ligamentina, Amblema plicata, and Lasmigona costata, while the three most rare were Anodontoides ferussacianus, E. torulosa rangiana, and Villosa fabalis. The high diversity of mussels along with the presence of federally listed and state-imperiled species warrants a pro-active approach to future protection of the aquatic resources of Muddy Creek.
The return of Castor canadensis (beaver) to areas of their former range has restored a natural disturbance regime to wetland landscapes in North America. We used aerial photographs to study wetland creation and modification by beaver in Acadia National Park, ME, during a period of beaver population expansion (1944–1997). We quantified the change in the number of available ponded wetlands in the landscape during the study period and documented an 89% increase in ponded wetlands between 1944 and 1997. Spatial and temporal patterns of beaver colonization and changes in wetland vegetation and hydrology were recorded at six time periods (1944, 1953, 1970, 1979, 1985, and 1997) for 33 beaver-created wetlands for which we had current amphibian assemblage data. Beaver colonization generally converted forested wetlands and riparian areas to open water and emergent wetlands, resulting in significant increases in the percentage of open water and emergent wetland habitat and a decrease in the percentage of forested wetland area at the study sites. Temporal colonization of beaver wetlands initially favored large sites occurring lower in the watersheds; sites that were impounded later were generally smaller, higher in the watershed, and more likely to be abandoned by the end of our study. Our results suggest that beaver have not only increased the number of available breeding sites in the landscape for pond-breeding amphibians, but also the resulting mosaic of active and abandoned beaver wetlands is likely to provide suitable breeding habitat for a diversity of species.
Many bat species have similar requirements for summer roosting sites leading to the potential for niche overlap and competition for roosts. Similarities in day roosts between bat species are rarely considered as a factor influencing population dynamics of species. We tracked Nycticeius humeralis (evening bats) and Eptesicus fuscus (big brown bats) to roost trees to evaluate the possibility of niche overlap in roost-site selection. Only tree height was significantly different between roosts used by the two species. Canopy cover, canopy height, dbh, tree species, tree condition, and roost type were not significantly different between the trees used by the two species. If competition for roosts exists between these species, similarities in roost trees may be important, especially as roost trees become scarce due to increased human alteration of roosting habitat. Competition for roost sites, in concert with other factors, may affect both competitors; however, populations of the inferior competitor, which is probably the evening bat, should be more negatively affected.
Two specimens of Sorex dispar (long-tailed shrew) were taken from the southern base of Stewart Mountain, NS on October 8th and 9th 2005. Stewart Mountain is located south of the Minas Basin, Bay of Fundy, and this population is clearly disjunct from other S. dispar populations, including those in Nova Scotia's Cobequid Mountains. This finding extends the range of S. dispar in Nova Scotia by 60 km southwest. Furthermore, because this new location documents the presence of S. dispar in a different mountain range than previous records, the discovery has significant implications for the conservation status and historical biogeography of this species in Nova Scotia.