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Four manufacturers now produce transmitters in the size range suitable for raptors (3-5% of body mass). Dummies of these transmitters will be displayed and harnessing techniques will be demonstrated. Estimates will be given for: cost, reliability, longevity, mass, availability, programmability, power output and other information essential in deciding on manufacturer and model.
Popular account of archaeological history of the area.
In convection systems with boiling springs, geysers, fumaroles, and other thermal features, the modes of heat flow become increasingly complex as a single liquid phase at depth rises into the near-surface environment where heat flows by convection of liquid and vapor and by conduction in high thermal gradients. This paper is mainly concerned with the changing patterns of conductive heat flow as related to channels of subsurface convective flow and to horizontal distance from spring vents. The primary data consist of temperatures measured in 13 cored drill holes as drilling progressed. Some temperatures plot convincingly on straight-line segments that suggest conductive gradients in rocks of nearly constant thermal conductivity. Temperature gradients and the conductive component of total heat flow nearly always decrease drastically downward; the gradient and heat flow of the lowest depth interval recognized in each hole is commonly only about 10 percent of the highest interval; the changes in gradient at interval boundaries are commonly interpreted as channels of near-boiling water or of cooler meteoric water. Temperature reversals are probably related to inflowing cooler water rather than to transient effects from recent changes. Some temperatures plot on curved segments that probably indicate dispersed convective upflow and boiling of water in ground penetrated by the drill hole. Other similar curved segments are too low in temperature for local boiling and are probably on the margins of hot upflow zones, reflecting conductive cooling of flowing water. The conifers of Yellowstone National Park (mainly lodgepole pine) seem to have normal growth characteristics where near-surface conductive heat flow is below about 200 heat-flow units (1 HFU = 10 -6 cal/cm 2 = 41.8 mW/m 2 ). Most areas of abnormal "stunted" trees (low ratio of height to base diameter, and low density of spacing) are characterized by conductive heat flows of about 250 to 350 HFU. The critical factor affecting growth is probably the seasonal maximum soil temperature at the root depths preferred by each form, rather than the heat flow as such. Heat flows up to 300 HFU are greatly dominated near the surface by conduction and are little affected by convection within the measured intervals. With increasing total heat flow above 300 HFU, the convection component, as indicated by snowfall calorimetry, becomes increasingly important. Snowfall calorimetry and tree growth as related to heat flow are calibrated by the heat-flow data considered here. Both snowfall calorimetry and tree growth patterns can be extrapolated rapidly, although without high precision, to thermal areas that lack subsurface data.
Ordinary quartz sand grains can be coated with pyrite for use in laboratory experiments on the genetic geochemistry of roll-type uranium deposits. The sand is first added to a ferric chloride solution. The slow addition of sodium hydroxide to the mixture gives the sand grains an iron oxide coating. This coating is then converted to pyrite by reaction with hydrogen sulfide, thus yielding a product suitable for experimental use.
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Contact rates vary widely among individuals in socially structured wildlife populations. Understanding the interplay of factors responsible for this variation is essential for planning effective disease management. Feral swine ( Sus scrofa ) are a socially structured species which pose an increasing threat to livestock and human health, and little is known about contact structure. We analyzed 11 GPS data sets from across the United States to understand the interplay of ecological and demographic factors on variation in co-location rates, a proxy for contact rates. Between-sounder contact rates strongly depended on the distance among home ranges (less contact among sounders separated by >2 km; negligible between sounders separated by >6 km), but other factors causing high clustering between groups of sounders also seemed apparent. Our results provide spatial parameters for targeted management actions, identify data gaps that could lead to improved management and provide insight on experimental design for quantitating contact rates and structure.
Managers charged with recovering endangered species in regulated river segments often have limited flexibility to alter flow regimes and want estimates of the expected population benefits associated with both flow and nonflow management actions. Disentangling impacts on different life stages from concurrently applied actions is essential for determining the effectiveness of each action, but difficult without models that integrate multiple information sources. Here, we develop and fit an integrated population model for endangered Rio Grande Silvery Minnow ( Hybognathus amarus ) in the Middle Rio Grande, New Mexico. We integrate catch per unit effort monitoring data collected during 2002–2018 with population estimates, data collected during rescue of minnow from drying pools, habitat availability estimates, laboratory results, releases of hatchery reared minnow, and expert opinion. We use expert elicitation to develop a larval carrying capacity index as an informed proxy for the complex interactions among flow, habitat, and life history in this species. We evaluate the model using out-of-sample forecasts of 2019 and 2020, develop an algorithm to identify supplemental water releases that maximize benefits to the minnow, and quantify the effectiveness of various actions. Experts generally agreed on the duration and timing of flow requirements and disagreed regarding the importance of different magnitudes. The integrated model with the larval carrying capacity index outperformed two alternative models in forecasting catch in 2019 and 2020. The model estimates that minnow abundance varied by more than three orders of magnitude between 2002 and 2018 and that in a few years recruitment was limited by spawner abundance. Evaluation of the expected benefits of flow and nonflow management actions to fall population abundance across different years suggests that efficient addition of water to the base hydrograph is the most effective action in most, but not all years. Many actions are effective only under certain hydrologic and population conditions and the effectiveness of different actions varies in different sections of the study area. Widespread water extraction and river regulation combined with periodic drought and ongoing climate change may necessitate creative management of federally listed fish species in arid systems informed by thorough analyses of management effectiveness.
Aeolian processes — the erosion, transport, and deposition of sediment by wind — play important geomorphological and ecological roles in drylands. These processes are known to impact the spatial patterns of soil, nutrients, plant‐available water, and vegetation in many dryland ecosystems. Tracers, such as rare earth elements and stable isotopes have been successfully used to quantify the transport and redistribution of sediment by aeolian processes in these ecosystems. However, many of the existing tracer techniques are labor‐intensive and cost‐prohibitive, and hence simpler alternative approaches are needed to track aeolian redistribution of sediments. To address this methodological gap, we test the applicability of a novel metal tracer‐based methodology for estimating post‐fire aeolian sediment redistribution, using spatio‐temporal measurements of low‐field magnetic susceptibility (MS). We applied magnetic metal tracers on soil microsites beneath shrub vegetation in recently burned and control treatments in a heterogeneous landscape in the Chihuahuan desert (New Mexico, USA). Our results indicate a spatially homogeneous distribution of the magnetic tracers on the landscape after post‐burn wind erosion events. MS decreased after wind erosion events on the burned shrub microsites, indicating that these areas functioned as sediment sources following the wildfire, whereas they are known to be sediment sinks in the undisturbed (e.g., not recently burned) ecosystem. This experiment represents the first step toward the development of a cost‐effective and non‐destructive tracer‐based approach to estimate the transport and redistribution of sediment by aeolian processes.
No abstract available.
Temporal and spatial patterns of landscape evolution strongly influence the temporal and spatial patterns of the archaeological record in drainage systems. In this geoarchaeological investigation we took a basin‐wide approach in assessing the soil stratigraphy, lithostratigraphy, and geochronology of alluvial deposits and associated buried soils in the Cottonwood River basin of east‐central Kansas. Patterns of landscape evolution emerge when stratigraphic sequences and radiocarbon chronologies are compared by stream size and landform type. In the valleys of high‐order streams (≥4th order) the Younger Dryas Chronozone (ca. 11,000–10,000 14 C yr B.P.) was characterized by slow aggradation accompanied by pedogenesis, resulting in the development of organic‐rich cumulic soils. Between ca. 10,000 and 4900 14 C yr B.P., aggradation punctuated by soil formation was the dominant process in those valleys. Alluvial fans formed on the margins of high‐order stream valleys during the early and middle Holocene (ca. 9000–5000 14 C yr B.P.) and continued to develop slowly until ca. 3000–2000 14 C yr B.P. The late‐Holocene record of high‐order streams is characterized by episodes of entrenchment, rapid aggradation, and slow aggradation punctuated by soil development. By contrast, the early and middle Holocene (ca. 10,000–5000 14 C yr B.P.) was a period of net erosion in the valleys of low‐order streams. However, during the late Holocene small valleys became zones of net sediment storage. Consideration of the effects of these patterns of landscape evolution on the archaeological record is crucial for accurately interpreting that record and searching for buried archaeological deposits dating to specific cultural periods.
No abstract available.
No abstract available.
Zooplankton transfer substantial energy in aquatic food webs and are used as indicators of environmental change. Syntheses of zooplankton community dynamics globally require datasets that span a wide range of environmental gradients; however, these datasets are limited due to methodological differences across programs, taxonomic inconsistencies, and a lack of standardized metadata. To reconcile these challenges, we created the Zooplankton International Geospatial (ZIG) dataset, which includes original zooplankton, water physical and chemical variables, and lake morphometric data from 311 inland lakes and reservoirs. ZIG includes waterbodies ranging in size from 0.005 to 82,100 km 2 and spanning broad latitudinal (−47.26 to 64.90) and longitudinal ranges (−165.04 to 176.53). Temporal coverage for individual waterbodies ranges between 1 and 60 yr with sampling frequency ranging from annually to weekly. With its extensive coverage and content, we consider ZIG to be a cornerstone for future investigations of global scale lake biodiversity change.
Preventing wildlife disease outbreaks is a priority for natural resource agencies, and management decisions can be urgent, especially in epidemic circumstances. With the emergence of SARS-CoV-2, wildlife agencies were concerned whether the activities they authorize might increase the risk of viral transmission from humans to North American bats, but had a limited amount of time in which to make decisions. We describe how decision analysis provides a powerful framework to analyze and reanalyze complex natural resource management problems as knowledge evolves. Coupled with expert judgment and avenues for the rapid release of information, risk assessment can provide timely scientific information for evolving decisions. In April 2020, the first rapid risk assessment was conducted to evaluate the risk of transmission of SARS-CoV-2 from humans to North American bats. Based on the best available information and relying heavily on expert judgment, the risk assessment found a small possibility of transmission during summer work activities. Following that assessment, additional knowledge and data emerged, such as bat viral challenge studies, that further elucidated the risks of human-to-bat transmission and culminated in a second risk assessment in the fall of 2020. We updated the first SARS-CoV-2 risk assessment with new management alternatives and new estimates of little brown bat ( Myotis lucifugus ) susceptibility, using findings from the fall 2020 assessment and other empirical studies. We found that new knowledge led to an 88% decrease in the median number of bats estimated to be infected per 1,000 encountered when compared to earlier results. The use of facemasks during, or a negative COVID-19 test or vaccination prior to, bat encounters further reduced those risks. Using a combination of decision analysis, expert judgment, rapid risk assessment, and efficient modes of information distribution, we provided timely science-based support to decision makers for summer bat work in North America.
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No abstract available.
The use of stored nutrients for reproduction represents an important component of life-history variation. Recent studies from several species have used stable isotopes to estimate the reliance on stored body reserves in reproduction. Such approaches rely on population-level dietary endpoints to characterize stored reserves (“capital”) and current diet (“income”). Individual variation in diet choice has so far not been incorporated in such approaches, but is crucial for assessing variation in nutrient allocation strategies. We investigated nutrient allocation to egg production in a large-bodied sea duck in northern Alaska, the king eider ( Somateria spectabilis ). We first used Bayesian isotopic mixing models to quantify at the population level the amount of endogenous carbon and nitrogen invested into egg proteins based on carbon and nitrogen isotope ratios. We then defined the isotopic signature of the current diet of every nesting female based on isotope ratios of eggshell membranes, because diets varied isotopically among individual king eiders on breeding grounds. We used these individual-based dietary isotope signals to characterize nutrient allocation for each female in the study population. At the population level, the Bayesian and the individual-based approaches yielded identical results, and showed that king eiders used an income strategy for the synthesis of egg proteins. The majority of the carbon and nitrogen in albumen (C: 86 ± 18%, N: 99 ± 1%) and the nitrogen in lipid-free yolk (90 ± 15%) were derived from food consumed on breeding grounds. Carbon in lipid-free yolk derived evenly from endogenous sources and current diet (exogenous C: 54 ± 24%), but source contribution was highly variable among individual females. These results suggest that even large-bodied birds traditionally viewed as capital breeders use exogenous nutrients for reproduction. We recommend that investigations of nutrient allocation should incorporate individual variation into mixing models to reveal intraspecific variation in reproductive strategies.