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Background Mercury (Hg) and methylmercury are widely considered significant issues for wildlife, and in particular, piscivorous birds due to their widespread availability and neurotoxic properties. Whereas a substantial number of studies of Hg contamination of Bald Eagles ( Haliaeetus leucocephalus ) have been conducted throughout the east coast of the United States, little has been done that directly addresses Hg contamination in Bald Eagles in Virginia, particularly the inland population. Methods We collected blood and feather samples from nestling Bald Eagles in the coastal plain, piedmont, and western regions of Virginia in an effort to determine which areas of the state were more likely to contain populations showing evidence of Hg toxicity. We analyzed the samples for total Hg using a Milestone DMA-80. Results Samples collected from individuals located in the coastal region exhibited low concentrations of Hg compared to those further inland located on freshwater rivers and reservoirs. Samples collected from the inland population exhibited levels in some areas that are approaching what may be considered to be sub-lethal to avian health (blood: mean 0.324 mg/kg, SE = 0.13, range = 0.06‒0.97 mg/kg; feather: mean = 8.433 mg/kg, SE = 0.3, range = 3.811‒21.14 mg/kg). Conclusions Even after accounting for known point-sources of Hg, the inland eagle population in Virginia is susceptible to concentrations of Hg that are significantly higher than their coastal counterparts. Moreover, several locations besides those currently known to be impacted by point-sources are exhibiting concentrations that are approaching a sub-lethal level.

To minimize wildlife-turbine conflict, the USFWS established voluntary National Wind Energy Guidelines (2003) that recommend an Avian or Avian and Bat Protection Plan (ABPP) for compliance with the Migratory Bird Treaty Act. [...]given the historical distribution of Golden Eagles in eastern North America and the potential negative genetic consequences of translocation programs, we recommend that introductions or translocations of western Golden Eagles into states east of the Mississippi be discontinued.

Artificial nesting islands, or rafts, are often deployed in common loon (Gavia immer) breeding territories to decrease negative impacts of mammalian predation and water-level fluctuations on nesting success. The management value of rafts has been demonstrated in other studies; however, no published studies have quantified the use or associated reproductive benefits of rafts on lakes exhibiting water-level fluctuations. These lakes constitute a major portion of loon nesting habitat in New England and the Midwest. We used long-term data sets from loon survey and raft management efforts on lakes with stable (SWL) and fluctuating water levels (FWL) in New Hampshire and Maine, USA, to compare raft-use patterns on both types of lakes. We then modeled the influence of percentage of nesting attempts on rafts, lake fluctuation type, and human development index on nesting success as a function of the number of nesting attempts. Loons used 76% of all rafts for nesting, and initial use patterns were similar between SWL and FWL lakes. Half (51%) of rafts used for nesting were first used during the initial year of deployment and 90% of those used were used by the third year. Based on our model, we would expect to see an 8.6% increase in nesting success associated with each successive categorical increase in raft use (0–33%, 33–60%, 60–100%). Nesting success varied with lake fluctuation type, increasing by 21.4% from FWL to SWL types. Our model estimated a 12.8% decrease in nesting success associated with an increasing human development index. Naturally nesting loons on FWL lakes are likely to display mean nesting success levels lower than those needed to sustain populations. We suggest that natural nesting habitat on lakes with fluctuating water levels during the loon nesting season may constitute an ecological trap warranting consideration of raft management. Findings in this study are germane for managing breeding loon populations, particularly those on reservoirs requiring permits from the Federal Energy Regulatory Commission.

This research is focused on explaining the concentrations of mercury found in juvenile bald eagles (Halieattus leucocephallus) as a function of the physical and anthropogenic landscape. Due to it's location in the food chain this species is susceptible to a wide range of contaminants (xenobiotics), particularly those that bioaccumulate and biomagnify as they move through the food chain. Previous research has indicated that areas in coastal environments are less susceptible to methylation than those in freshwater environments. Sampling efforts for this research were conducted in such a manner as to obtain an equivalent number of samples from the coastal plain (expected to be low mercury) and the inland regions (expected to be statistically significantly higher). In all cases, results indicated that both feather and blood mercury concentrations were higher in the inland population (Blood: Prob > t = 0.0003, Feather: Prob > t = 0.0002). Utilizing classification and regression tree models (CART), we were able to relate metrics such as the percent of deciduous forest, percent of mixed forest, percent of pasture, and percent of wetland to measured blood mercury concentrations. We also found that the best models were produced using the USGS HUC 12 watersheds (the smallest watershed produced by the USGS). Moreover, we found that metrics describing the amount and type of fragmentation within the watersheds exhibited a significant influence on measured blood mercury concentrations. Contrary to previous research, we found wetlands to be negatively associated with higher blood mercury, whereas the abundance of core forest and a larger patch density (PD) in the deciduous and mixed land cover classes was positively associated with higher blood mercury concentrations. We also found that a higher percentage of pasture was associated with higher blood mercury.

This research is focused on explaining the concentrations of mercury found in juvenile bald eagles (Halieattus leucocephallus) as a function of the physical and anthropogenic landscape. Due to it's location in the food chain this species is susceptible to a wide range of contaminants (xenobiotics), particularly those that bioaccumulate and biomagnify as they move through the food chain. Previous research has indicated that areas in coastal environments are less susceptible to methylation than those in freshwater environments. Sampling efforts for this research were conducted in such a manner as to obtain an equivalent number of samples from the coastal plain (expected to be low mercury) and the inland regions (expected to be statistically significantly higher). In all cases, results indicated that both feather and blood mercury concentrations were higher in the inland population (Blood: Prob > t = 0.0003, Feather: Prob > t = 0.0002). Utilizing classification and regression tree models (CART), we were able to relate metrics such as the percent of deciduous forest, percent of mixed forest, percent of pasture, and percent of wetland to measured blood mercury concentrations. We also found that the best models were produced using the USGS HUC 12 watersheds (the smallest watershed produced by the USGS). Moreover, we found that metrics describing the amount and type of fragmentation within the watersheds exhibited a significant influence on measured blood mercury concentrations. Contrary to previous research, we found wetlands to be negatively associated with higher blood mercury, whereas the abundance of core forest and a larger patch density (PD) in the deciduous and mixed land cover classes was positively associated with higher blood mercury concentrations. We also found that a higher percentage of pasture was associated with higher blood mercury.

Colinus virginianus (Northern Bobwhite) populations showed signs of decline beginning in the early 1900s and are part of a growing list of wildlife species dependent on early successional habitat whose populations are suffering similar fates. Among the numerous factors that contributed to these range-wide declines, most significant are habitat loss and fragmentation due to changes in land use and land cover. In an effort to document landscape composition and cover-type changes, we mapped and analyzed landscape features along 7 breeding bird survey routes on Maryland's Eastern Shore in 2 different years spaced 55 years apart, 1964 and 2019. We calculated total patch area and conducted a randomization test for paired study design to test for differences in land cover after 55 years between the 5 landscape attributes that influence populations dependent on early successional vegetation within an agriculture-dominated landscape. The 5 landscape attributes were agriculture, forest cover, hedgerow length, early successional habitat, and development. In the 55-year span, agricultural land declined from 58.4% to 48.8% and had the largest change in cover area across the 5 landscape attributes. Developed land increased from 7.5% to 12.2%, while forested land remained the same at 24.4%.

Technological advancements have facilitated the implementation of realistic, terrestrial-based complex 33-beam galactic cosmic radiation simulations (GCR Sim) to now probe central nervous system functionality. This work expands considerably on prior, simplified GCR simulations, yielding new insights into responses of male and female mice exposed to 40–50 cGy acute or chronic radiations relevant to deep space travel. Results of the object in updated location task suggested that exposure to acute or chronic GCR Sim induced persistent impairments in hippocampus-dependent memory formation and reconsolidation in female mice that did not manifest robustly in irradiated male mice. Interestingly, irradiated male mice, but not females, were impaired in novel object recognition and chronically irradiated males exhibited increased aggressive behavior on the tube dominance test. Electrophysiology studies used to evaluate synaptic plasticity in the hippocampal CA1 region revealed significant reductions in long-term potentiation after each irradiation paradigm in both sexes. Interestingly, network-level disruptions did not translate to altered intrinsic electrophysiological properties of CA1 pyramidal cells, whereas acute exposures caused modest drops in excitatory synaptic signaling in males. Ultrastructural analyses of CA1 synapses found smaller postsynaptic densities in larger spines of chronically exposed mice compared to controls and acutely exposed mice. Myelination was also affected by GCR Sim with acutely exposed mice exhibiting an increase in the percent of myelinated axons; however, the myelin sheathes on small calibur (< 0.3 mm) and larger (> 0.5 mm) axons were thinner when compared to controls. Present findings might have been predicted based on previous studies using single and mixed beam exposures and provide further evidence that space-relevant radiation exposures disrupt critical cognitive processes and underlying neuronal network-level plasticity, albeit not to the extent that might have been previously predicted.