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The Nerodia erythrogaster neglecta (Copper-bellied Watersnake) population north of 40 degrees north latitude is categorized as threatened under the US Endangered Species Act. Previous efforts to use mark-recapture to estimate population size have been unsuccessful because there were so few initial captures. We therefore evaluated the status of the largest presumed subpopulation of this population by using strip transects to provide a conservative (maximum) estimate of density and population size of adults. Our results indicate that the largest presumed adult Copper-bellied Watersnake metapopulation north of 40 degrees north latitude is extremely small, with a total size of 94 ± 22 adults, and is characterized by a population density of 1.17 ± 0.27 adult snakes/ha (95 % CI = 0.73–1.87 snake/ha). This Copper-bellied Watersnake population appears to be in danger of extirpation within the foreseeable future. Recovery will require protecting existing wetland complexes and restoring wetlands and the surrounding upland habitats.
In oviparous species that lack parental care, fitness of the mother depends on the selection of a high-quality nest site, as mothers do not compensate for poor incubation environment post-hatching. Near the northern range limit of Glyptemys insculpta (Wood Turtle), short summers and cool temperatures may be factors that limit population persistence because potential nest sites may not provide adequate conditions for successful egg incubation in some years. We quantified nest-site selection by examining soil temperature and substrate composition of real Wood Turtle nests (n = 5) and constructed false nests. False nests comprised two treatments: negative-test false nests (n = 5) constructed on beaches not used by females, and positive-test false nests (n = 5) constructed on beaches used by females but in microsites not chosen by females. Temperature was measured as total thermal units and mean temperature during the diel cycle. Soil composition was quantified using moisture content, organic content, and grain-size distribution. Soil temperature was the most important factor in nest-site selection. Temperatures and total thermal units were significantly higher and more variable in real nests than in false nests, except during the night. Soil composition was not significantly different among treatments. Grain sizes ranged from fine to gravel, and real nests contained mainly (58% to 96%) medium sand or larger grains. There was little variation in soil moisture among real nests, suggesting that females were choosing specific humidity conditions for nesting. Our findings can be directly applied to protecting nesting beaches for Wood Turtles, which are considered a species at risk.
Baseline information on the current status of rare mussel populations in a given water body is necessary to better understand the effects of actions to protect or enhance populations. We conducted river-wide surveys in French Creek, known for its mussel abundance, to quantify population-level indicators that could be used for measuring viability of Epioblasma torulosa rangiana (Northern Riffleshell), a critically imperiled freshwater mussel, in recovering or reintroduced populations. We estimated multiple attributes of Northern Riffleshell populations, including longitudinal distribution, densities and abundances, sex-specific age structure, and mortality rates. Northern Riffleshell has been documented in French Creek since at least the early 1900s and is distributed unevenly throughout the creek (12 of 32 sites in a bimodal pattern), with no animals found in the upper third of the creek. At sites containing Northern Riffleshell, site-specific densities ranged from 0.009–6.668 m2. Maximum age of Northern Riffleshell ranged from 7–11 years at four sites with evidence of sustained recruitment (i.e., uneven age structure). Proportions of individuals in each age class were similar at each site, even though total numbers of animals differed by up to two orders of magnitude. Significantly more males than females were found in early ages (1–3), but no significant differences were found in older age classes. There were no significant differences in mortality rates (both sexes combined) at all four sites. However, mortality rates differed significantly between the sexes at older ages (ages 6–10) at the one site with enough individuals for a comparison, suggesting greater reproductive costs or selective predation for females. The population attributes of Northern Riffleshell from French Creek are important benchmarks for setting restoration goals and measuring success in other systems that share a similar biogeography to French Creek, but whose fauna has been depleted (e.g., many Ohio River tributaries).
Potamilus alatus (Pink Heelsplitter) is a rare freshwater mussel in the Ottawa River drainage (Ontario/Québec, Canada), at the northeastern limit of its distribution. There are few historical records, and one old specimen from an uncertain locality. The discovery of the Pink Heelsplitter in the Ottawa River drainage dates from 1863. A few specimens were reported up to 1901, but it was August 2001 before another specimen was found in the Ottawa River, as an empty shell at Upper Duck Island, near Ottawa. From 2001 to 2005, the authors found this freshwater mussel at four localities along the Ottawa River, and two in the tributary South Nation River. Records include 4 living specimens and 12 empty shells, of which 8 were in fresh condition. The Pink Heelsplitter seems to persist sparsely in the Ottawa River, but it may have been extirpated from one of its tributaries (South Nation River) before its discovery due to mortality associated with Dreissena polymorpha (Zebra Mussel).
We investigated diet and its relationship to trophic morphology in Sternotherus odoratus (Stinkpot) in northwestern Pennsylvania on Presque Isle, Lake Erie. Three taxa were most prevalent in fecal samples: invasive Eurasian mussels, small snails, and trichopteran larvae. No sexual difference in diet was apparent, although males had relatively wider heads than females. Significant positive correlation of proportion of sample volume composed of mussels with width of the head and alveolar surfaces was accompanied by nonsignificant negative correlation of proportion composed of snails with both variables. The results thus suggest a shift in molluscan prey preference with increasing size of the trophic apparatus. Total consumption of mollusks was high relative to most other reports of Stinkpot diet. In the Laurentian Great Lakes, the Stinkpot is the second turtle species found to prey heavily upon invasive mussels and thereby participate in transferring production from the pelagic zone to the littoral zone.
Impacts of highway construction on streams in the central Appalachians are a growing concern as new roads are created to promote tourism and economic development in the area. Alterations to the streambed of a first-order stream, Sauerkraut Run, Hardy County, WV, during construction of a highway overpass included placement and removal of a temporary culvert, straightening and regrading of a section of stream channel, and armourment of a bank with a reinforced gravel berm. We surveyed longitudinal profiles and cross sections in a reference reach and the altered reach of Sauerkraut Run from 2003 through 2007 to measure physical changes in the streambed. During the four-year period, three high-flow events changed the streambed downstream of construction including channel widening and aggradation and then degradation of the streambed. Upstream of construction, at a reinforced gravel berm, bank erosion was documented. The reference section remained relatively unchanged. Knowledge gained by documenting channel changes in response to natural and anthropogenic variables can be useful for managers and engineers involved in highway construction projects.
We investigated nutrient limitation of periphyton and phytoplankton in Cape Cod, MA coastal plain freshwater ponds. We assayed periphyton growth response to nitrogen (N) and phosphorus (P) in situ, assessed phytoplankton growth in growth chambers, and measured ratios of dissolved N and P in surface waters to determine if nutrient ratios were accurate predictors of nutrient limitation. In ponds receiving low groundwater nutrient inputs, periphyton responded weakly to addition of N or P alone, but responded strongly to addition of N P. In these ponds, increases in both N and P were also required to increase phytoplankton growth. In ponds receiving high groundwater nutrient inputs, increased N P were also required to increase phytoplankton growth. We found no indication that high nutrient inputs shifted pond phytoplankton to P limitation. There was no consistent correlation between dissolved N:P and whether periphyton was limited by either N or P or co-limited by N and P. Strong and widespread co-limitation by N and P suggested that greater attention should be given to both N and P when assessing the threat of nutrient enrichment to fresh waters. Effects of increased periphyton and phytoplankton growth on the unique flora of coastal plain ponds are not known, but bear increased attention given large increases of N in groundwater in many locations, the sensitivity of pond algae to nutrient supply, and the status of coastal plain ponds as high conservation priorities.
Two new specimens of the rare deep sea eel genus Neocyema were collected in the western North Atlantic in June 2006 and September 2008. Previously the genus was known only from the two type specimens, collected in the South Atlantic in 1971. External morphology and osteology indicate that the new specimens probably belong to the described species Neocyema erythrosoma. Their capture in the North Atlantic provides support for the hypothesis that Neocyema is the adult form of the enigmatic larva Leptocephalus holti.
Ectoparasitism of nesting birds is known to impact reproduction for many species including cavity-nesting swallows and ground-nesting colonial seabirds. Little information is available from wading birds (e.g., herons, egrets, ibises). We documented skin-eating dermestid beetle abundance in 261 wading-bird nests in seven heronries located in northeastern US estuaries during 1991–2000. Beetles were collected after fledglings were no longer using the nest. We examined all twigs and debris for larval and adult beetles, and excavated holes in twigs to count pupating insects. In addition, nest size was evaluated. Dermestes nidum (dermestid beetle) larvae were prominent members of nest faunal communities in all estuaries. We detected no evidence that beetle abundance correlated with wading-bird species, nest reuse, nest substrate species, or nest-collection date. Regression analysis and partial correlation analysis identified nest size, colony, and year as factors showing a significant relationship with beetle abundance after accounting for all known factors.
We report forest bird population trends from 1987–2005 at a 280.7-ha site in Chester, MA. Our study site consisted primarily of mid-successional (70–90 yr old) forest in a landscape of similar, non-fragmented forest. Using point counts at 100 stations, we detected 94 species in early June over all years. Mean numbers of species and detections/yr were 57 and 1104, respectively. Species richness and total detections were stable (P ≤ 0.05). We analyzed trends for the 36 most frequently detected species. Four species exhibited significant increasing trends and 10 significant declining trends; 22 species were stable or exhibited no significant trend (P ≤ 0.05). Whether a species was a resident, short-distance, migrant, or Neotropical migrant did not appear to be a determinative factor for trends. Trends were more readily explained by (I) areal and structural expansion of mature forest conditions and (II) forestry treatments that affected 70 ha (25%) of the study site. We report few changes in species abundances that could not be plausibly explained by intra-site habitat changes and no mysterious or alarming changes in the first 19 years of this study.
Many authors have recently used changes in arrival dates of migratory breeding birds as a measure of environmental change due to global warming. In this paper, I present a comparative analysis of the intra-annual variability in first arrival dates for 107 species of migratory breeding birds in Maine. Data come from volunteer observers in the southern two-thirds of the state from 1994 through 2005. Using the Julian date for each first arrival, standard deviations were tabulated for each species in each year. The results indicate that some species, specifically leaf-gleaning insectivores and aerial insectivores, have relatively low variance of first arrival dates while other species show more protracted migrations and hence greater variability around the mean arrival date. Post hoc considerations of the patterns of variability suggest that diet may be an important determinant of variance in arrival date. The data indicate that researchers should concentrate on species with lower variances of arrival date to increase the statistical power for testing changes in arrival dates as global warming proceeds.
Bird collisions in Manhattan (New York City) were studied by analyzing collision data collected from 1997 to 2008 by Project Safe Flight (PSF) participants, representing one of the largest collision monitoring efforts in the nation. Over 5400 bird collisions were recorded during this period, two-thirds of which were fatal. Collisions involved 104 bird species, primarily from the warbler, sparrow, and thrush families, and mostly during spring and fall migration. Most collisions were documented to occur during the day at the lower levels of buildings where large glass exteriors reflected abundant vegetation, or where transparent windows exposed indoor vegetation. Most collisions in Manhattan likely occurred at a smaller number of high-collision sites where strike rates of well over 100 birds per year are considerably higher than previously reported rates. We suggest here that improving our understanding of the factors involved in collisions at such sites could greatly assist in reducing bird collisions.
Alces americanus (Moose) are relatively new to Labrador, having only colonized the area in the late 1940s, and little is known about this population. We conducted large-scale aerial surveys for Moose in a 122,000-km2 area during winter 2000 and in a 29,900-km2 area in winter 2001. Moose densities were low in each area (1.6–3.0 Moose per 100 km2). Bull:cow ratios were nearly even and calf:cow ratios were relatively high, indicative of a population exposed to little hunting or predation pressure. Twinning rates were low, suggesting low range productivity. Moose used riparian areas and hardwood stands in higher proportion than their availability in winter (P < 0.05). Open habitats (conifer-lichen woodlands, bogs and fens, burned forest, and barren areas) were used in lower proportion than their availability. These data may provide the basis for developing habitat suitability maps for Moose in late winter across central Labrador.
Hemigrapsus sanguineus Asian Shore Crab is an introduced but now common crab found intertidally along the Connecticut coastline. Little is known of its subtidal occurrence. This species was found to be seasonally abundant subtidally, at depths varying from 1.3–3.9 m, during a 2-year study conducted within a commercial marina in Clinton Harbor, CT. Hemigrapsus sanguineus was trapped at three subtidal locations, with highest concentrations observed during the winter. A total of 2020 crabs were caught: 1255 males, 741 females, and 24 crabs that were 9 mm or smaller and sexually indistinguishable. Large males with carapace widths between 45–48 mm were captured at all three locations. These sizes are among the largest reported for this species. This work documents year-round use of subtidal habitat by Asian Shore Crab in Long Island Sound.