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At least 1,621 records · Page 90Linked to original sources

Habitat use by postfledging American black ducks in Maine and New Brunswick

We examined habitat use by 112 postfledging American black ducks ( Anas rubripes ) in eastern Maine and southwestern New Brunswick from September through early December of 1985, 1986, and 1987. Ducks were captured on Moosehorn National Wildlife Refuge (NWR), Maine. Palustrine Emergent Wetland was the most preferred habitat type. Riverine habitats were avoided in September, but were used more than, or in proportion to, their availability in November as ice formed on lentic habitats. Black ducks used a greater variety of habitat types during the day than at night, when ducks used mostly large (>30 ha) Emergent Wetland marshes. Managed impoundments of Moosehorn NWR were the most used wetlands (66% of all diurnal, 90% of all nocturnal locations). For black duck management, we propose maintaining large (30-50 ha) marshes containing dense emergent vegetation that are located near a complex of diverse wetland types.

Maine↗

Relationship of deer and moose populations to previous winters' snow

(1) Linear regression was used to relate snow accumulation during single and consecutive winters with white-tailed deer ( Odocoileus virginianus ) fawn:doe ratios, moose ( Alces alces ) twinning rates and calf:cow ratios, and annual changes in deer and moose populations. Significant relationships were found between snow accumulation during individual winters and these dependent variables during the following year. However, the strongest relationships were between the dependent variables and the sums of the snow accumulations over the previous three winters. The percentage of the variability explained was 36 to 51. (2) Significant relationships were also found between winter vulnerability of moose calves and the sum of the snow accumulations in the current, and up to seven previous, winters, with about 49% of the variability explained. (3) No relationship was found between wolf numbers and the above dependent variables. (4) These relationships imply that winter influences on maternal nutrition can accumulate for several years and that this cumulative effect strongly determines fecundity and/or calf and fawn survivability. Although wolf ( Canis lupus L.) predation is the main direct mortality agent on fawns and calves, wolf density itself appears to be secondary to winter weather in influencing the deer and moose populations.

Journal of Animal Ecology↗

Evaluation of thermal antinociceptive effects after intramuscular administration of hydromorphone hydrochloride to American kestrels ( Falco sparverius )

Objective —To evaluate the antinociceptive and sedative effects and duration of action of hydromorphone hydrochloride after IM administration to American kestrels ( Falco sparverius ). Animals —11 healthy 2-year-old American kestrels. Procedures —Hydromorphone (0.1, 0.3, and 0.6 mg/kg) and an equivalent volume of saline (0.9% NaCl) solution (control treatment) were administered IM to kestrels in a masked randomized complete crossover study design. Foot withdrawal response to a thermal stimulus was determined 30 to 60 minutes before (baseline) and 0.5, 1.5, 3, and 6 hours after treatment administration. Agitation-sedation scores were determined 3 to 5 minutes before each thermal test. Results —Hydromorphone at 0.6 mg/kg, IM, significantly increased the thermal foot withdrawal threshold, compared with the response after administration of saline solution, for up to 3 hours, and hydromorphone at 0.1, 0.3, and 0.6 mg/kg, IM, significantly increased withdrawal responses for up to 6 hours, compared with baseline values. No significant differences in mean sedation-agitation scores were detected between hydromorphone and saline solution treatments; however, appreciable sedation was detected in 4 birds when administered 0.6 mg of hydromorphone/kg. Conclusions and Clinical Relevance —Hydromorphone at the doses evaluated significantly increased the thermal nociception threshold for American kestrels for 3 to 6 hours. Additional studies with other types of stimulation, formulations, dosages, routes of administration, and testing times are needed to fully evaluate the analgesic and adverse effects of hydromorphone in kestrels and other avian species and the use of hydromorphone in clinical settings.

American Journal of Veterinary Research↗

Pharmacokinetics of hydromorphone hydrochloride after intravenous and intramuscular administration of a single dose to American kestrels (Falco sparverius)

Objective —To determine the pharmacokinetics of hydromorphone hydrochloride after IV and IM administration in American kestrels ( Falco sparverius ). Animals —12 healthy adult American kestrels. Procedures —A single dose of hydromorphone (0.6 mg/kg) was administered IM (pectoral muscles) and IV (right jugular vein); the time between IM and IV administration experiments was 1 month. Blood samples were collected at 5 minutes, 1 hour, and 3 hours (n = 4 birds); 0.25, 1.5, and 9 hours (4); and 0.5, 2, and 6 hours (4) after drug administration. Plasma hydromorphone concentrations were determined by means of liquid chromatography with mass spectrometry, and pharmacokinetic parameters were calculated with a noncompartmental model. Mean plasma hydromorphone concentration for each time was determined with naïve averaged pharmacokinetic analysis. Results —Plasma hydromorphone concentrations were detectable in 2 and 3 birds at 6 hours after IM and IV administration, respectively, but not at 9 hours after administration. The fraction of the hydromorphone dose absorbed after IM administration was 0.75. The maximum observed plasma concentration was 112.1 ng/mL (5 minutes after administration). The terminal half-life was 1.25 and 1.26 hours after IV and IM administration, respectively. Conclusion and Clinical Relevance —Results indicated hydromorphone hydrochloride had high bioavailability and rapid elimination after IM administration, with a short terminal half-life, rapid plasma clearance, and large volume of distribution in American kestrels. Further studies regarding the effects of other doses, other administration routes, constantrate infusions, and slow release formulations on the pharmacokinetics of hydromorphone hydrochloride and its metabolites in American kestrels may be indicated.

American Journal of Veterinary Research↗

Pharmacokinetics of buprenorphine hydrochloride following intramuscular and intravenous administration to American kestrels ( Falco sparverius )

Objective —To determine the pharmacokinetics of buprenorphine hydrochloride after IM and IV administration to American kestrels ( Falco sparverius ). Animals —13 healthy 3-year-old captive-bred American kestrels. Procedures —Buprenorphine hydrochloride (0.6 mg/kg) was administered IM to all birds. Blood samples were collected at 9 times, ranging from 5 minutes to 9 hours after drug administration. Plasma buprenorphine concentrations were measured by use of tandem liquid chromatography–mass spectrometry. Pharmacokinetic parameters were determined by use of least squares linear regression and noncompartmental analysis of naïve pooled data. After a washout period of 2 weeks, the same dose of buprenorphine was administered IV to all birds and blood samples were collected at the same times after drug administration. Results —Maximum plasma buprenorphine concentration was achieved within 5 minutes after IM administration. For IM administration, bioavailability was 94.8% and elimination half-life was 92.1 minutes. For IV administration, steady-state volume of distribution was 4,023.8 mL/kg, plasma clearance was 49.2 mL/min/kg, and elimination half-life was 105.5 minutes. Conclusions and Clinical Relevance —Buprenorphine was rapidly absorbed, and bioavailability was good after IM administration to American kestrels. Plasma buprenorphine concentrations were > 1 ng/mL for 9 hours after both IM and IV administration. These results, in combination with those of a pharmacodynamic study, suggested that the analgesic effects of buprenorphine could last at least 6 to 9 hours in this species. Further investigations of the duration of analgesic effects, multiple-dose protocols, and potential adverse effects of buprenorphine are warranted in American kestrels and other raptors.

American Journal of Veterinary Research↗

Syn-extensional plutonism and peak metamorphism in the albion-raft river-grouse creek metamorphic core complex

The Cassia plutonic complex (CPC) is a group of variably deformed, Oligocene granitic plutons exposed in the lower plate of the Albion-Raft River- Grouse Creek (ARG) metamorphic core complex of Idaho and Utah. The plutons range from granodiorite to garnet-bearing, leucogranite, and during intrusion, sillimanite- grade peak metamorphism and ductile attenuation occurred in the country rocks and normal-sense, amphibolite-grade deformation took place along the Middle Mountain shear zone. U-Pb zircon geochronology from three variably deformed plutons exposed in the lower plate of the ARG metamorphic core complex revealed that each zircon is comprised of inherited cores (dominantly late Archean) and Oligocene igneous overgrowths. Within each pluton, a spread of concordant ages from the Oligocene zircon overgrowths is interpreted as zircon recycling within a long-lived magmatic system. The plutons of the CPC have very low negative whole rock ??Nd values of -26 to -35, and initial Sr values of 0.714 to 0.718, consistent with an ancient, crustal source. Oxygen isotope ratios of the Oligocene zircon overgrowths from the CPC have an average ??18O value of 5.40 ?? 0.63 permil (2SD, n = 65) with a slight trend towards higher ??18O values through time. The ??18O values of the inherited cores of the zircons are more variable at 5.93 ?? 1.51 permil (2SD, n = 29). Therefore, we interpret the plutons of the CPC as derived, at least in part, from melting Archean crust based on the isotope geochemistry. In situ partial melting of the exposed Archean basement that was intruded by the Oligocene plutons of the CPC is excluded as the source for the CPC based on field relationships, age and geochemistry. Correlations between Ti and Hf concentrations in zircons from the CPC suggest that the magmatic system may have become hotter (higher Ti concentration in zircon) and less evolved (lower Hf in zircon concentration) through time. Therefore, the CPC represents prolonged or episodic magmatism system (32-25 Ma), and the intrusions were each accompanied by sillimanite-grade deformation and extension. The Oligocene magmatism and peak metamorphism preserved in the ARG metamorphic core complex are likely related to regional trends in mantle-derived magmatism that led to protracted heating, melting and mobilization of the deeper crust.

American Journal of Science↗

Erosion of an ancient mountain range, the Great Smoky Mountains, North Carolina and Tennessee

Analysis of 10 Be and 26 Al in bedrock (n=10), colluvium (n=5 including grain size splits), and alluvial sediments (n=59 including grain size splits), coupled with field observations and GIS analysis, suggest that erosion rates in the Great Smoky Mountains are controlled by subsurface bedrock erosion and diffusive slope processes. The results indicate rapid alluvial transport, minimal alluvial storage, and suggest that most of the cosmogenic nuclide inventory in sediments is accumulated while they are eroding from bedrock and traveling down hill slopes. Spatially homogeneous erosion rates of 25 - 30 mm Ky −1 are calculated throughout the Great Smoky Mountains using measured concentrations of cosmogenic 10 Be and 26 Al in quartz separated from alluvial sediment. 10 Be and 26 Al concentrations in sediments collected from headwater tributaries that have no upstream samples (n=18) are consistent with an average erosion rate of 28 ± 8 mm Ky −1 , similar to that of the outlet rivers (n=16, 24 ± 6 mm Ky −1 ), which carry most of the sediment out of the mountain range. Grain-size-specific analysis of 6 alluvial sediment samples shows higher nuclide concentrations in smaller grain sizes than in larger ones. The difference in concentrations arises from the large elevation distribution of the source of the smaller grains compared with the narrow and relatively low source elevation of the large grains. Large sandstone clasts disaggregate into sand-size grains rapidly during weathering and downslope transport; thus, only clasts from the lower parts of slopes reach the streams. 26 Al/ 10 Be ratios do not suggest significant burial periods for our samples. However, alluvial samples have lower 26 Al/ 10 Be ratios than bedrock and colluvial samples, a trend consistent with a longer integrated cosmic ray exposure history that includes periods of burial during down-slope transport. The results confirm some of the basic ideas embedded in Davis’ geographic cycle model, such as the reduction of relief through slope processes, and of Hack’s dynamic equilibrium model such as the similarity of erosion rates across different lithologies. Comparing cosmogenic nuclide data with other measured and calculated erosion rates for the Appalachians, we conclude that rates of erosion, integrated over varying time periods from decades to a hundred million years are similar, the result of equilibrium between erosion and isostatic uplift in the southern Appalachian Mountains.

Tennessee, North Carolina↗

Nutrients and sediment in frozen-ground runoff from no-till fields receiving liquid-dairy and solid-beef manures

Nutrients and sediment in surface runoff from frozen agricultural fields were monitored within three small (16.0 ha [39.5 ac] or less), adjacent basins at a no-till farm in southwest Wisconsin during four winters from 2003 to 2004 through 2006 to 2007. Runoff depths and flow-weighted constituent concentrations were compared to determine the impacts of surface-applied liquid-dairy or solid-beef manure to frozen and/or snow-covered ground. Despite varying the manure type and the rate and timing of applications, runoff depths were not significantly different among basins within each winter period. Sediment losses were low (generally less than 22 kg ha −1 [20 lb ac −1 ] in any year) and any statistical differences in sediment concentrations among basins were not related to the presence or absence of manure or the amount of runoff. Concentrations and losses of total nitrogen and total phosphorus were significantly increased in basins that had either manure type applied less than one week preceding runoff. These increases occurred despite relatively low application rates. Lower concentrations and losses were measured in basins that had manure applied in fall and early winter and an extended period of time (months) had elapsed before the first runoff event. The highest mean, flow-weighted concentrations of total nitrogen (31.8 mg L −1 ) and total phosphorus (10.9 mg L −1 ) occurred in winter 2003 to 2004, when liquid-dairy manure was applied less than one week before runoff. On average, dissolved phosphorus accounted for over 80% of all phosphorus measured in runoff during frozen-ground periods. The data collected as part of this study add to the limited information on the quantity and quality of frozen-ground runoff at field edges, and the results highlight the importance of manure management decisions during frozen-ground periods to minimize nutrients lost in surface runoff.

Wisconsin↗

Nitrogen transport within an agricultural landscape: insights on how hydrology, biogeochemistry, and the landscape intersect to control the fate and transport of nitrogen in the Mississippi Delta

Nitrogen (N) is a ubiquitous contaminant throughout agricultural landscapes due to both the application of inorganic and organic fertilizers to agricultural fields and the general persistence of nitrate (NO 3 ) in oxygenated aqueous environments (Denver et al. 2010; Domagalski et al. 2008; Green et al. 2008; Coupe 2001; Nolan and Stoner 2000). In order to understand why excess N occurs various hydrologic systems (environments), it is important to consider potential sources, the locations of these sources in the watershed, and the timing of the application of sources with respect to the movement of water. To learn how to manage N in a watershed, it is necessary to identify and quantify flow paths and biogeochemical conditions, which ultimately combine to determine transport and fate. If sources, transport mechanisms, and biogeochemical controls were uniformly distributed, it would be possible to manage N uniformly throughout a watershed. However, uniform conditions are rare to nonexistent in the natural world and in the landscape altered for agricultural production. In order to adjust management activities on the landscape to have the greatest effect, it is important to understand the fate and transport N within the intersection of hydrology and biogeochemistry, that is, to understand the extent and duration of the hydrologic and biogeochemical controls as N is routed through and among each hydrologic compartment.

Mississippi Delta↗

Distribution, abundance, and habitat associations of a large bivalve (Panopea generosa) in a eutrophic, fjord estuary

Marine bivalves are important ecosystem constituents and frequently support valuable fisheries. In many nearshore areas, human disturbance—including declining habitat and water quality—can affect the distribution and abundance of bivalve populations, and complicate ecosystem and fishery management assessments. Infaunal bivalves, in particular, are frequently cryptic and difficult to detect; thus, assessing potential impacts on their populations requires suitable, scalable methods for estimating abundance and distribution. In this study, population size of a common benthic bivalve (the geoduck Panopea generosa ) is estimated with a Bayesian habitat-based model fit to scuba and tethered camera data in Hood Canal, a fjord basin in Washington state. Densities declined more than two orders of magnitude along a north—south gradient, concomitant with patterns of deepwater dissolved oxygen, and intensity and duration of seasonal hypoxia. Across the basin, geoducks were most abundant in loose, unconsolidated, sand substrate. The current study demonstrates the utility of using scuba, tethered video, and habitat models to estimate the abundance and distribution of a large infaunal bivalve at a regional (385-km 2 ) scale.

Washington↗

Distributed shear of subglacial till due to Coulomb slip

In most models of the flow of glaciers on till beds, it has been assumed that till behaves as a viscoplastic fluid, despite contradictory evidence from laboratory studies. In accord with this assumption, displacement profiles measured in subglacial till have been fitted with viscoplastic models by estimating the stress distribution. Here we present a model that illustrates how observed displacement profiles can result from till deformation resisted solely by Coulomb friction. Motion in the till bed is assumed to be driven by brief departures from static equilibrium caused by fluctuations in effective normal stress. These fluctuations result from chains of particles that support intergranular forces that are higher than average and that form and fail at various depths in the bed during shearing. Newton’s second law is used to calculate displacements along slip planes and the depth to which deformation extends in the bed. Consequent displacement profiles are convex upward, similar to those measured by Boulton and colleagues at Breidamerkurjökull, Iceland. The model results, when considered together with the long-term and widespread empirical support for Coulomb models in soils engineering, indicate that efforts to fit viscoplastic flow models to till displacement profiles may be misguided.

Journal of Glaciology↗

A new high-precision borehole-temperature logging system used at GISP2, Greenland, and Taylor Dome, Antarctica

We describe a high-precision (0.1–1.0 mK) borehole-temperature (BT) logging system developed at the United States Geological Survey (USGS) for use in remote polar regions. We discuss calibration, operational and data-processing procedures, and present an analysis of the measurement errors. The system is modular to facilitate calibration procedures and field repairs. By interchanging logging cables and temperature sensors, measurements can be made in either shallow air-filled boreholes or liquid-filled holes up to 7 km deep. Data can be acquired in either incremental or continuous-logging modes. The precision of data collected by the new logging system is high enough to detect and quantify various thermal effects at the milli-Kelvin level. To illustrate this capability, we present sample data from the 3 km deep borehole at GISP2, Greenland, and from a 130 m deep air-filled hole at Taylor Dome, Antarctica. The precision of the processed GISP2 continuous temperature logs is 0.25–0.34 mK, while the accuracy is estimated to be 4.5 mK. The effects of fluid convection and the dissipation of the thermal disturbance caused by drilling the borehole are clearly visible in the data. The precision of the incremental Taylor Dome measurements varies from 0.11 to 0.32 mK. depending on the wind strength during the experiments. With this precision, we found that temperature fluctuations and multi-hour trends in the BT measurements correlate well with atmospheric-pressure changes.

Journal of Glaciology↗

Female American Kestrel survives double amputation

Free-ranging raptors are susceptible to a variety of injuries, many of which are sustained while pursuing and/or capturing live prey. Injuries hindering an individual’s ability to capture prey, such as partial blindness, damage to the bill, and foot or leg injuries, are debilitating and potentially life-threatening. However, there are ample observations in the literature of free-ranging raptors with eye (Bedrosian and St.Pierre 2007), bill (Strobel and Haralson-Strobel 2009) and foot and leg injuries (Blodget et al. 1990, Murza et al. 2000, Dwyer 2006, Bedrosian and St.Pierre 2007), suggesting that some individuals are able to compensate for their injuries if only partial functionality is lost (e.g., loss of only one eye). Reports of injuries resulting in the complete loss of functionality (e.g., loss of both eyes) are rare as individuals suffering such severe trauma presumably do not survive long. Here we report the capture on a bal-chatri trap of an American Kestrel (Falco sparverius; hereafter kestrel) with previous amputation of both legs

Journal of Raptor Research↗

Spatial and temporal patterns in golden eagle diets in the western United States, with implications for conservation planning

Detailed information on diets and predatory ecology of Golden Eagles ( Aquila chrysaetos ) is essential to prioritize prey species management and to develop landscape-specific conservation strategies, including mitigation of the effects of energy development across the western United States. We compiled published and unpublished data on Golden Eagle diets to (1) summarize available information on Golden Eagle diets in the western U.S., (2) compare diets among biogeographic provinces, and (3) discuss implications for conservation planning and future research. We analyzed 35 studies conducted during the breeding season at 45 locations from 1940–2015. Golden Eagle diet differed among western ecosystems. Lower dietary breadth was associated with desert and shrub-steppe ecosystems and higher breadth with mountain ranges and the Columbia Plateau. Correlations suggest that percentage of leporids in the diet is the factor driving overall diversity of prey and percentage of other prey groups in the diet of Golden Eagles. Leporids were the primary prey of breeding Golden Eagles in 78% of study areas, with sciurids reported as primary prey in 18% of study areas. During the nonbreeding season, Golden Eagles were most frequently recorded feeding on leporids and carrion. Golden Eagles can be described as both generalist and opportunistic predators; they can feed on a wide range of prey species but most frequently feed on abundant medium-sized prey species in a given habitat. Spatial variations in Golden Eagle diet likely reflect regional differences in prey community, whereas temporal trends likely reflect responses to long-term change in prey populations. Evidence suggests dietary shifts from traditional (leporid) prey can have adverse effects on Golden Eagle reproductive rates. Land management practices that support or restore shrub-steppe ecosystem diversity should benefit Golden Eagles. More information is needed on nonbreeding-season diet to determine what food resources, such as carrion, are important for overwinter survival.

Journal of Raptor Research↗

Drivers of flight performance of California Condors (Gymnogyps californianus)

Flight behavior of soaring birds depends on a complex array of physiological, social, demographic, and environmental factors. California Condors ( Gymnogyps californianus ) rely on thermal and orographic updrafts to subsidize extended bouts of soaring flight, and their soaring flight performance is expected to vary in response to environmental variation and, potentially, with experience. We collected 6298 flight tracks described by high-frequency GPS telemetry data from five birds ranging in age from 1 to 19 yr old and followed over 32 d in summer 2016. Using these data, we tested the hypothesis that climb rate, an indicator of flight performance, would be related to the topographic and meteorological variables the bird experienced, and also to its age. Climb rate was greater when condors were flying in faster winds and during environmental conditions that were conducive to updraft development. However, we found no effect of age on climb rate. Although many of these relationships were expected based on flight theory, the lack of an effect of age was unexpected. Our work expands understanding of the relationship condors have with the environment, and it also suggests the potential for as-yet unexplored complexity to this relationship. As such, this study provides insight into avian flight behavior and, because flight performance influences bird behavior and exposure to anthropogenic risk, it has potential consequences for development of conservation management plans.

California↗

Sediment transport model including short-lived radioisotopes: Model description and idealized test cases

Geochronologies derived from sediment cores in coastal locations are often used to infer event bed characteristics such as deposit thicknesses and accumulation rates. Such studies commonly use naturally occurring, short-lived radioisotopes, such as Beryllium-7 ( 7 Be) and Thorium-234 ( 234 Th), to study depositional and post-depositional processes. These radioisotope activities, however, are not generally represented in sediment transport models that characterize coastal flood and storm deposition with grain size patterns and deposit thicknesses. We modified the Community Sediment Transport Modeling System (CSTMS) to account for reactive tracers and used this capability to represent the behavior of these short-lived radioisotopes on the sediment bed. This paper describes the model and presents results from a set of idealized, one-dimensional (vertical) test cases. The model configuration represented fluvial deposition followed by periods of episodic storm resuspension. Sensitivity tests explored the influence on seabed radioisotope profiles by the intensities of bioturbation and wave resuspension and the thickness of fluvial deposits. The intensity of biodiffusion affected the persistence of fluvial event beds as evidenced by 7 Be. Both resuspension and biodiffusion increased the modeled seabed inventory of 234 Th. A thick fluvial deposit increased the seabed inventory of 7 Be and 234 Th but mixing over time greatly reduced the difference in inventory of 234 Th in fluvial deposits of different thicknesses.

Journal of Marine Science and Engineering↗

Soil reservoir dynamics of ophidiomyces ophidiicola, the causative agent of snake fungal disease

Wildlife diseases pose an ever-growing threat to global biodiversity. Understanding how wildlife pathogens are distributed in the environment and the ability of pathogens to form environmental reservoirs is critical to understanding and predicting disease dynamics within host populations. Snake fungal disease (SFD) is an emerging conservation threat to North American snake populations. The causative agent, Ophidiomyces ophidiicola (Oo), is detectable in environmentally derived soils. However, little is known about the distribution of Oo in the environment and the persistence and growth of Oo in soils. Here, we use quantitative PCR to detect Oo in soil samples collected from five snake dens. We compare the detection rates between soils collected from within underground snake hibernacula and associated, adjacent topsoil samples. Additionally, we used microcosm growth assays to assess the growth of Oo in soils and investigate whether the detection and growth of Oo are related to abiotic parameters and microbial communities of soil samples. We found that Oo is significantly more likely to be detected in hibernaculum soils compared to topsoils. We also found that Oo was capable of growth in sterile soil, but no growth occurred in soils with an active microbial community. A number of fungal genera were more abundant in soils that did not permit growth of Oo, versus those that did. Our results suggest that soils may display a high degree of both general and specific suppression of Oo in the environment. Harnessing environmental suppression presents opportunities to mitigate the impacts of SFD in wild snake populations.

Journal of Fungi↗