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At least 217 records · Page 12Linked to original sources

USGS2012

Differences in survival and growth in hatchery and stream environments, and in maturation of residuls in a stream, between progeny of hatchery and wild steelhead (Study sites: Brushy Fork Creek and Dworshak Hatchery; Stocks:Dworshak hatchery and Fish Creek wild; Year classes: 1992 and 1993)

Freshwater survival in hatchery and natural rearing environments was compared between progeny of hatchery (H) and wild (W) steelhead Oncorhynchus mykiss from the Clearwater River drainage in Idaho. Adults from Dworshak National Fish Hatchery and wild adults from Fish Creek fish were artificially spawned, and their progeny were genetically marked at the PEPA allozyme locus and released together as unfed fry in production facilities at the hatchery and in Brushy Fork Creek, also in the Clearwater River drainage, in a common garden design. Survival was higher for H than for W progeny at the hatchery but lower for H than for W progeny in Brushy Fork, indicating reduced fitness of the hatchery population for natural rearing and suggesting domestication as the cause. Survival at the hatchery was lower than is typical due to disease outbreaks. Survival of the first year-class of experimental fish to smolt release was only 18%. Survival of H fish was 3.8 times that of W fish under these poor survival conditions. All fish from the second year-class died halfway through the scheduled 10 month rearing period. Survival of H fish was 5.2 times that of W fish to when 1% of the initial fry were still alive indicating that W fish succumbed to the epizootic sooner than did H fish. Emigrants from the Brushy Fork study reach were sampled for three years and fish residing in the study reach were sampled for six years following fry release. Most emigrants were one or two years old and too small to be smolts (mean fork length at age-2 = 93 mm). Survival in Brushy Fork was lower for H than for W fish of the first year-class. Survival of the second year-class was higher for H than for W fish during the first two months in the stream but was lower for H than for W fish thereafter, and net survival from release to ages 3 and older was also lower for H than for W fish if our emigrant samples were representative (periods of inoperative emigrant traps prevented certainty about this). Differences between progeny groups were also found for growth (H>W) and condition (H>W) in the hatchery and downstream migration success of hatchery-reared fish after release (H>W), and for growth (H<W for one year-class; H>W for the other), condition (H>W), downstream dispersal (H>W for one year-class; H=W for the other), and maturation of residuals (ovaries weight was greater for H than for W females at ages 4 and 5; testes weight was less for H than for W age-3 males of one year-class) in Brushy Fork. A thunderstorm-induced power outage interrupted flow to the incubation trays at the hatchery and compromised a major tenet of the common garden design for the second year-class, possibly contributing to the inconsistency in relative survivals in Brushy Fork between year-classes. The storm caused the incubation environment to differ between the stocks as a result of reduced oxygen levels and substantially higher densities for H alevins. This difference was illustrated by a 55% loss for H fish during the event, about twice that for W fish.

Idaho↗

USGS2018

Effects of rearing environment on behavior of captive-reared whooping cranes

Whooping cranes ( Grus americana ) are 1 of the most endangered bird species in North America. In 1999 the Whooping Crane Eastern Partnership was formed to establish a migratory population of whooping cranes in eastern North America. These efforts have been extremely successful in terms of adult survival but reproductive success post-release has been low. One hypothesis developed to explain such low reproductive success is that captive-rearing techniques fail to prepare the birds to be effective parents. Captive-reared whooping cranes at the U.S. Geological Survey, Patuxent Wildlife Research Center, Laurel, Maryland, are either reared by humans in crane costumes or by surrogate conspecific adults. We hypothesized that the 2 captive-rearing techniques differentially shaped chick behavior. To test this, we measured chick behavior daily as well as when chicks were placed in novel environments. Twice per day, every day, 5-minute focal observations were conducted on each chick. When they were introduced to a novel environment, 10-minute focal observations were conducted within 1 hour of introduction. The 2 groups differed significantly: costume-reared chicks were, on average, more stationary than parent-reared birds. These data suggest that future research should be done to determine whether or not rearing technique could have longterm effects on post-release behavior and reproductive success

Conference Paper↗

USGS2020

Correlations along a 140 km transect in the westernmost Peach Spring Tuff, and tracing changing facies through depositional environments

Tephrochronology is the correlation of tephra beds and tuffs by various means, and it is an important tool in refining stratigraphic and structural interpretations. The 18.78 Ma Peach Spring Tuff (PST) is a large-volume ignimbrite that was deposited across a ~200 km x 360 km area of southeastern California, northwestern Arizona, and southern Nevada. The PST is a valuable stratigraphic marker in several stratigraphic sequences in this area. In this study, the field characteristics, mineral abundance, and feldspar composition of eight ignimbrite locations are examined along a 140 km swath across the northwestern extent of the PST in the Mojave Desert. Based on geochronologic or paleomagnetic data, five of the ignimbrites are PST, and three are possible PST ignimbrites do not have supporting geochronologic or paleomagnetic data. In 53 regionally dispersed locations of the PST, including the three possible PST ignimbrites in this study, the overlying and underlying sedimentary deposits are described in order to determine the depositional changes, if any, resulting from the geologically instantaneous deposition of the ignimbrite. Of the 53 locations, 37 locations allow interpretation of the pre- and post-PST depositional environments. Of the 37, 25 have an upward fining-thinning trend indicating that the deposition of the ignimbrite resulted in (1) disruption and change in local stream gradients and sediment supply, (2) a long period of time for depositional systems to propagate to and regenerate at a location, or (3) a lack of re-establishment of the pre-PST environments. However, 12 have no significant change, so there was minimal disruption to the depositional system.

Arizona, California, Nevada↗

USGS2020

The collection and analysis of Bay of Fundy sediment under contract between the association of US delegates to the Gulf of Maine Council on the marine environment and eastern Charlotte waterways for contaminant monitoring and analysis

This report presents data obtained through the EcoSystem Indicator Partnership (ESIP) which was established in 2006 to improve understanding and to inform researchers, managers, and citizens about the status and trends of ecosystem health in the Gulf of Maine (http://www.gulfofmaine.org/2/esip-homepage/). In its efforts to compile information on contaminant indicators in the Gulf of Maine, ESIP identified gaps in monitoring information and worked in partnership with the Gulf of Maine Council and other organizations to fill these gaps. The monitoring and data gaps identified by ESIP indicated that data on contaminants in intertidal/subtidal sediments were lacking for the Bay of Fundy. To address this data gap, the Association of US Delegates to the Gulf of Maine Council on the Marine Environment contracted Eastern Charlotte Waterways Inc., an independent non-governmental organization, to conduct a contaminant monitoring and analysis project funded by Environment and Climate Change Canada . This report summarizes the data produced from this sediment analysis project.

Gulf of Maine↗

USGS2010

On the irrigation requirements of cottonwood (Populus fremontii and Populus deltoides var. wislizenii) and willow (Salix gooddingii) grown in a desert environment

Native tree plots have been established in river irrigation districts in the western U.S. to provide habitat for threatened and endangered birds. Information is needed on the effective irrigation requirements of the target species. Cottonwood (Populus spp.) and willow (Salix gooddingii) trees were grown for seven years in an outdoor plot in a desert environment in Tucson, Arizona. Plants were allowed to achieve a nearly complete canopy cover over the first four years, then were subjected to three daily summer irrigation schedules of 6.20??mm??d -1 ; 8.26??mm??d -1 and 15.7??mm??d -1 . The lowest irrigation rate was sufficient to maintain growth and high leaf area index for cottonwoods over three years, while willows suffered considerable die-back on this rate in years six and seven. These irrigation rates were applied April 15-September 15, but only 0.88??mm??d -1 was applied during the dormant period of the year. Expressed as a fraction of reference crop evapotranspiration (ET o ), recommended annual water applications plus precipitation (and including some deep drainage) were 0.83 ET o for cottonwood and 1.01 ET o for willow. Current practices tend to over-irrigate restoration plots, and this study can provide guidelines for more efficient water use. ?? 2010 Elsevier Ltd.

Journal of Arid Environments↗

USGS2016

Assessing the role of climate and resource management on groundwater dependent ecosystem changes in arid environments with the Landsat archive

Groundwater dependent ecosystems (GDEs) rely on near-surface groundwater. These systems are receiving more attention with rising air temperature, prolonged drought, and where groundwater pumping captures natural groundwater discharge for anthropogenic use. Phreatophyte shrublands, meadows, and riparian areas are GDEs that provide critical habitat for many sensitive species, especially in arid and semi-arid environments. While GDEs are vital for ecosystem services and function, their long-term (i.e. ~ 30 years) spatial and temporal variability is poorly understood with respect to local and regional scale climate, groundwater, and rangeland management. In this work, we compute time series of NDVI derived from sensors of the Landsat TM, ETM +, and OLI lineage for assessing GDEs in a variety of land and water management contexts. Changes in vegetation vigor based on climate, groundwater availability, and land management in arid landscapes are detectable with Landsat. However, the effective quantification of these ecosystem changes can be undermined if changes in spectral bandwidths between different Landsat sensors introduce biases in derived vegetation indices, and if climate, and land and water management histories are not well understood. The objective of this work is to 1) use the Landsat 8 under-fly dataset to quantify differences in spectral reflectance and NDVI between Landsat 7 ETM + and Landsat 8 OLI for a range of vegetation communities in arid and semiarid regions of the southwestern United States, and 2) demonstrate the value of 30-year historical vegetation index and climate datasets for assessing GDEs. Specific study areas were chosen to represent a range of GDEs and environmental conditions important for three scenarios: baseline monitoring of vegetation and climate, riparian restoration, and groundwater level changes. Google's Earth Engine cloud computing and environmental monitoring platform is used to rapidly access and analyze the Landsat archive along with downscaled North American Land Data Assimilation System gridded meteorological data, which are used for both atmospheric correction and correlation analysis. Results from the cross-sensor comparison indicate a benefit from the application of a consistent atmospheric correction method, and that NDVI derived from Landsat 7 and 8 are very similar within the study area. Results from continuous Landsat time series analysis clearly illustrate that there are strong correlations between changes in vegetation vigor, precipitation, evaporative demand, depth to groundwater, and riparian restoration. Trends in summer NDVI associated with riparian restoration and groundwater level changes were found to be statistically significant, and interannual summer NDVI was found to be moderately correlated to interannual water-year precipitation for baseline study sites. Results clearly highlight the complementary relationship between water-year PPT, NDVI, and evaporative demand, and are consistent with regional vegetation index and complementary relationship studies. This work is supporting land and water managers for evaluation of GDEs with respect to climate, groundwater, and resource management.

Remote Sensing of Environment↗

USGS2019

Corrigendum to “A comprehensive analysis of interseasonal and interannual energy and water balance dynamics in semiarid shrubland and forest ecosystems” [Sci. Total Environ. 651 (2019) 381–398]

The authors regret the omission of an author, funding sources, and key support staff. The omitted author and their affiliation is: Matthew J Germino US Geological Survey, Forest and Rangeland Ecosystem Science Center, Boise ID 83706. The correct citation should be: Valayamkunnath, P., Sridhar, V., Zhao, W. Allen, R.G., and Germino, M.J., 2019. A comprehensive analysis of interseasonal and interannual energy and water balance dynamics in semiarid shrubland and forest ecosystems. Science of The Total Environment, 651, 381–398. Additions to the Acknowledgements include: Funding was provided by the U.S. Bureau of Land Management and US Department of Agriculture National Research Initiative. Jeremy Greth, Clarence Robinson, Ricardo Trezza, Jeppe Kjaersgaard, and many other field technicians from Idaho State University and Boise State University assisted in setting up the experiment. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Science of the Total Environment↗

USGS2020

Recent advances in understanding and measurement of mercury in the environment: Terrestrial Hg cycling

This review documents recent advances in terrestrial mercury cycling. Terrestrial mercury (Hg) research has matured in some areas, and is developing rapidly in others. We summarize the state of the science circa 2010 as a starting point, and then present the advances during the last decade in three areas: land use, sulfate deposition, and climate change . The advances are presented in the framework of three Hg “gateways” to the terrestrial environment: inputs from the atmosphere, uptake in food, and runoff with surface water . Among the most notable advances: • The Arctic has emerged as a hotbed of Hg cycling, with high stream fluxes and large stores of Hg poised for release from permafrost with rapid high-latitude warming. • The bi-directional exchange of Hg between the atmosphere and terrestrial surfaces is better understood, thanks largely to interpretation from Hg isotopes; the latest estimates place land surface Hg re-emission lower than previously thought. • Artisanal gold mining is now thought responsible for over half the global stream flux of Hg. • There is evidence that decreasing inputs of Hg to ecosystems may bring recovery sooner than expected, despite large ecosystem stores of legacy Hg. • Freshly deposited Hg is more likely than stored Hg to methylate and be incorporated in rice. • Topography and hydrological connectivity have emerged as master variables for explaining the disparate response of THg and MeHg to forest harvest and other land disturbance. These and other advances reported here are of value in evaluating the effectiveness of the Minamata Convention on reducing environmental Hg exposure to humans and wildlife.

Science of the Total Environment↗

USGS1983

Complexation of copper by aquatic humic substances from different environments

The copper-complexing properties of aquatic humic substances isolated from eighteen different environments were characterized by potentiometric titration, using a cupric ion selective electrode. Potentiometric data were analyzed using FITEQL, a computer program for the determination of chemical equilibrium constants from experimental data. All the aquatic humic substances could be modelled as having two types of Cu(II)-binding sites: one with K equal to about 10 6 and a concentration of 1.0 ± 0.4 × 10 −6 M(mg C) −1 and another with K equal to about 10 8 and a concentration of 2.6 ± 1.6 × 10 −7 M(mg C) −1 . A method is described for estimating the Cu(II)-binding sites associated with dissolved humic substances in natural water based on a measurement of dissolved organic carbon, which may be helpful in evaluating chemical processes controlling speciation of Cu and bioavailability of Cu to aquatic organisms.

Science of the Total Environment↗

USGS2015

Context of ancient aqueous environments on Mars from in situ geologic mapping at Endeavour Crater

Using the Mars Exploration Rover Opportunity , we have compiled one of the first field geologic maps on Mars while traversing the Noachian terrain along the rim of the 22 km diameter Endeavour Crater (Latitude −2°16′33″, Longitude −5°10′51″). In situ mapping of the petrographic, elemental, structural, and stratigraphic characteristics of outcrops and rocks distinguishes four mappable bedrock lithologic units. Three of these rock units predate the surrounding Burns formation sulfate-rich sandstones and one, the Matijevic Formation, represents conditions on early Mars predating the formation of Endeavour Crater. The stratigraphy assembled from these observations includes several geologic unconformities. The differences in lithologic units across these unconformities record changes in the character and intensity of the Martian aqueous environment over geologic time. Water circulated through fractures in the oldest rocks over periods long enough that texturally and elementally significant alteration occurred in fracture walls. These oldest pre-Endeavour rocks and their network of mineralized and altered fractures were preserved by burial beneath impact ejecta and were subsequently exhumed and exposed. The alteration along joints in the oldest rocks and the mineralized veins and concentrations of trace metals in overlying lithologic units is direct evidence that copious volumes of mineralized and/or hydrothermal fluids circulated through the early Martian crust. The wide range in intensity of structural and chemical modification from outcrop to outcrop along the crater rim shows that the ejecta of large (>8 km in diameter) impact craters is complex. These results imply that geologic complexity is to be anticipated in other areas of Mars where cratering has been a fundamental process in the local and regional geology and mineralogy.

Journal of Geophysical Research E: Planets↗

USGS2017

From data to decisions: Processing information, biases, and beliefs for improved management of natural resources and environments

Our different kinds of minds and types of thinking affect the ways we decide, take action, and cooperate (or not). Derived from these types of minds, innate biases, beliefs, heuristics, and values (BBHV) influence behaviors, often beneficially, when individuals or small groups face immediate, local, acute situations that they and their ancestors faced repeatedly in the past. BBHV, though, need to be recognized and possibly countered or used when facing new, complex issues or situations especially if they need to be managed for the benefit of a wider community, for the longer-term and the larger-scale. Taking BBHV into account, we explain and provide a cyclic science-infused adaptive framework for (1) gaining knowledge of complex systems and (2) improving their management. We explore how this process and framework could improve the governance of science and policy for different types of systems and issues, providing examples in the area of natural resources, hazards, and the environment. Lastly, we suggest that an “Open Traceable Accountable Policy” initiative that followed our suggested adaptive framework could beneficially complement recent Open Data/Model science initiatives.

Earth's Future↗

USGS2016

Constraining the relative importance of raindrop- and flow-driven sediment transport mechanisms in postwildfire environments and implications for recovery time scales

Mountain watersheds recently burned by wildfire often experience greater amounts of runoff and increased rates of sediment transport relative to similar unburned areas. Given the sedimentation and debris flow threats caused by increases in erosion, more work is needed to better understand the physical mechanisms responsible for the observed increase in sediment transport in burned environments and the time scale over which a heightened geomorphic response can be expected. In this study, we quantified the relative importance of different hillslope erosion mechanisms during two postwildfire rainstorms at a drainage basin in Southern California by combining terrestrial laser scanner-derived maps of topographic change, field measurements, and numerical modeling of overland flow and sediment transport. Numerous debris flows were initiated by runoff at our study area during a long-duration storm of relatively modest intensity. Despite the presence of a well-developed rill network, numerical model results suggest that the majority of eroded hillslope sediment during this long-duration rainstorm was transported by raindrop-induced sediment transport processes, highlighting the importance of raindrop-driven processes in supplying channels with potential debris flow material. We also used the numerical model to explore relationships between postwildfire storm characteristics, vegetation cover, soil infiltration capacity, and the total volume of eroded sediment from a synthetic hillslope for different end-member erosion regimes. This study adds to our understanding of sediment transport in steep, postwildfire landscapes and shows how data from field monitoring can be combined with numerical modeling of sediment transport to isolate the processes leading to increased erosion in burned areas.

California↗

USGS2018

Snow sublimation in mountain environments and its sensitivity to forest disturbance and climate warming

Snow sublimation is an important component of the snow mass balance, but the spatial and temporal variability of this process is not well understood in mountain environments. This study combines a process‐based snow model (SnowModel) with eddy covariance (EC) measurements to investigate (1) the spatio‐temporal variability of simulated snow sublimation with respect to station observations, (2) the contribution of snow sublimation to the ablation of the snowpack, and (3) the sensitivity and response of snow sublimation to bark beetle‐induced forest mortality and climate warming across the north‐central Colorado Rocky Mountains. EC‐based observations of snow sublimation compared well with simulated snow sublimation at stations dominated by surface and canopy sublimation, but blowing snow sublimation in alpine areas was not well captured by the EC instrumentation. Water balance calculations provided an important validation of simulated sublimation at the watershed scale. Simulated snow sublimation across the study area was equivalent to 28% of winter precipitation on average, and the highest relative snow sublimation fluxes occurred during the lowest snow years. Snow sublimation from forested areas accounted for the majority of sublimation fluxes, highlighting the importance of canopy and sub‐canopy surface sublimation in this region. Simulations incorporating the effects of tree mortality due to bark‐beetle disturbance resulted in a 4% reduction in snow sublimation from forested areas. Snow sublimation rates corresponding to climate warming simulations remained unchanged or slightly increased, but total sublimation losses decreased by up to 6% because of a reduction in snow covered area and duration.

Water Resources Research↗

USGS2018

Processes and facies relationships in a Lower(?) Devonian rocky shoreline depositional environment, East Lime Creek Conglomerate, south‐western Colorado, USA

Rocky shorelines are relatively common features along modern coastlines, but few have been recognized in the geological record. The hard substrates of rocky shorelines telescope the width of offshore marine environments, thus the diagnostic deposits observed in such settings today have a low preservation potential due to small accommodation space and high‐energy conditions. This study recognized previously overlooked, laterally extensive Lower(?) Devonian rocky shoreline deposits in the San Juan Mountains of south‐western Colorado. The newly defined lithostratigraphic unit, the East Lime Creek Conglomerate (ELCC), is 0–23 m thick, unconformably overlying Proterozoic crystalline rocks and unconformably overlain by the Upper Devonian Ignacio Formation and/or Elbert Formation. The unit mostly consists of clast‐supported cobble‐boulder conglomerate with rounded quartzite clasts up to 1.4 m in length interbedded with thin sandstone layers and lenses. Sandstones in the ELCC are distinguished from unconformably overlying Upper Devonian sedimentary rocks because they have sericite cements. Most importantly, there are buttressing relationships between the ELCC and underlying Proterozoic crystalline rocks interpreted as palaeo‐sea cliffs, palaeo‐wave‐cut platforms and palaeo‐tombolos. A proposed rocky shoreline facies model includes headlands with upper shoreface‐beachface tabular cobble‐boulder gravels sourced from rock fall talus, nearshore subaqueous debris‐flow deposits and intervening pocket beaches with imbricated, stratified pebble‐cobble gravel sheets. Palaeocurrent data ( n = 338) from clast long‐axis orientations, imbrication and cross‐bedding indicate south‐to‐north transport roughly onshore‐offshore to a coastline consisting of alternating rocky headlands and pocket beaches. This Lower(?) Devonian unit documents a previously unrecognized episode in the geological history of south‐western Colorado.

Colorado↗

USGS2018

Occupancy modeling species–environment relationships with non‐ignorable survey designs

Statistical models supporting inferences about species occurrence patterns in relation to environmental gradients are fundamental to ecology and conservation biology. A common implicit assumption is that the sampling design is ignorable and does not need to be formally accounted for in analyses. The analyst assumes data are representative of the desired population and statistical modeling proceeds. However, if data sets from probability and non‐probability surveys are combined or unequal selection probabilities are used, the design may be non‐ignorable. We outline the use of pseudo‐maximum likelihood estimation for site‐occupancy models to account for such non‐ignorable survey designs. This estimation method accounts for the survey design by properly weighting the pseudo‐likelihood equation. In our empirical example, legacy and newer randomly selected locations were surveyed for bats to bridge a historic statewide effort with an ongoing nationwide program. We provide a worked example using bat acoustic detection/non‐detection data and show how analysts can diagnose whether their design is ignorable. Using simulations we assessed whether our approach is viable for modeling data sets composed of sites contributed outside of a probability design. Pseudo‐maximum likelihood estimates differed from the usual maximum likelihood occupancy estimates for some bat species. Using simulations we show the maximum likelihood estimator of species–environment relationships with non‐ignorable sampling designs was biased, whereas the pseudo‐likelihood estimator was design unbiased. However, in our simulation study the designs composed of a large proportion of legacy or non‐probability sites resulted in estimation issues for standard errors. These issues were likely a result of highly variable weights confounded by small sample sizes (5% or 10% sampling intensity and four revisits). Aggregating data sets from multiple sources logically supports larger sample sizes and potentially increases spatial extents for statistical inferences. Our results suggest that ignoring the mechanism for how locations were selected for data collection (e.g., the sampling design) could result in erroneous model‐based conclusions. Therefore, in order to ensure robust and defensible recommendations for evidence‐based conservation decision‐making, the survey design information in addition to the data themselves must be available for analysts. Details for constructing the weights used in estimation and code for implementation are provided.

Ecological Applications↗

USGS2018

Long-term persistence of horse fecal DNA in the environment makes equids particularly good candidates for non-invasive sampling

Fecal DNA collected noninvasively can provide valuable information about genetic and ecological characteristics. This approach has rarely been used for equids, despite the need for conservation of endangered species and management of abundant feral populations. We examined factors affecting the efficacy of using equid fecal samples for conservation genetics. First, we evaluated two fecal collection methods (paper bag vs. ethanol). Then, we investigated how time since deposition and month of collection impacted microsatellite amplification success and genotyping errors. Between May and November 2014, we collected feral horse fecal samples of known age each month in a feral horse Herd Management Area in western Colorado and documented deterioration in the field with photographs. Samples collected and dried in paper bags had significantly higher amplification rates than those collected and stored in ethanol. There was little difference in the number of loci that amplified per sample between fresh fecal piles and those that had been exposed to the environment for up to 2 months (in samples collected in paper bags). After 2 months of exposure, amplification success declined. When comparing fresh (0–2 months) and old (3–6 months) fecal piles, samples from fresh piles had more matching genotypes across samples, better amplification success and less allelic dropout. Samples defecated during the summer and collected within 2 months of deposition had highest number of genotypes matching among samples, and lowest rates of amplification failure and allelic dropout. Due to the digestive system and amount of fecal material produced by equids, as well as their occurrence in arid ecosystems, we suggest that they are particularly good candidates for noninvasive sampling using fecal DNA.

Colorado↗

USGS2024

Evaluating mountain lion diet before and after a removal of feral horses in a semiarid environment

Non-native species can affect ecosystems by influencing native predator-prey dynamics. Therefore, management interventions designed to remove non-natives may inadvertently lead to increased predation on native species. Feral horses are widely distributed throughout the arid parts of western North America. A growing body of research indicates that horses can be an important prey species to mountain lions in ecosystems where they overlap. In December 2020, the Bureau of Land Management removed 455 horses from the Delamar Mountains, Nevada, USA. We leveraged this management intervention to implement a before–after–control–impact study to test hypotheses about predation on horses and native ungulates. We predicted (1) that horses would comprise an important part of the diet in this mixed-prey community, (2) following removal, the proportion of horses in the diet would decrease and native ungulates would increase, and (3) mountain lion home ranges overlapping the treatment areas would increase in response to decreased prey availability. From 2018 to 2022, we investigated 1360 clusters from 29 GPS-collared lions and identified 1056 prey items. To model the probability of a predation event (a kill), we fit a mixed-effects logistic regression model for ungulate prey as a function of lion sex, treatment area (in/out), and treatment period (pre-/post-removal). We used a log-linear regression model to evaluate changes in home range size. The most common prey were mule deer (55%), feral horses (32%), and coyotes (4%). Twenty-two of 29 lions consumed horses, although the rate of horse consumption was highly variable across individuals. Horses of both sexes and all age classes were predated. In contrast to predictions, our models detected no effect of removals on diet composition (β interaction = 0.30 ± 1.1), nor did the removal influence home range size (β interaction = 0.02 ± 0.02). Despite a 46% reduction in horse abundance, we found no evidence for prey-switching following the horse removal treatment. Removal magnitude, rapid horse immigration, and/or behavioral specialization of individual mountain lions may help explain these results. Our findings have important implications for mountain lion and feral horse management in arid environments characterized by high prey diversity, but low prey abundance.

Nevada↗

USGS2022

Do pharmaceuticals in the environment pose a risk to wildlife?

The vast majority of knowledge related to the question of, “To what extent do pharmaceuticals in the environment pose a risk to wildlife?”, stems from the Asian vulture crisis (>99% decline of some species of old-world vultures on the Indian subcontinent related to the veterinary use of the non-steroidal anti-inflammatory drug (NSAID) diclofenac). The hazard of diclofenac and other NSAIDs (carprofen, flunixin, ketoprofen, nimesulide, phenylbutazone) to vultures and other avian species has since been demonstrated; indeed only meloxicam and tolfenamic acid have been found to be vulture-safe. Since diclofenac was approved for veterinary use in Spain and Italy in 2013 (home to ~95% of vultures in Europe), the risk of NSAIDs to vultures in these countries has become one of the principal concerns related to pharmaceuticals and wildlife. Many of the other bodies of work on pharmaceutical exposure, hazard and risk to wildlife also relate to adverse effects in birds, (e.g., poisoning of scavenging birds in North America and Europe from animal carcasses containing pentobarbital; secondary and even tertiary poisoning of birds exposed to pesticides used in veterinary medicine as cattle dips; migratory birds as a vector for the transfer of antimicrobial and antifungal resistance). While there is some research related to endocrine disruption in reptiles and potential exposure of aerial insectivores, there remain numerous knowledge gaps for risk posed by pharmaceuticals to amphibians, reptiles and mammals. Developing non-invasive sampling techniques and new approach methodologies (e.g., genomic, in vitro , in silico , in ovo ) are important if we are to bridge the current knowledge gaps without extensive vertebrate testing.

Environmental Toxicology and Chemistry↗