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At least 811 records · Page 45Linked to original sources
USGS2020

A transect through Vermont's most famous volcano - Mount Ascutney

The Cretaceous Ascutney Mountain igneous complex affords a classic exposure of the White Mountain Igneous Suite. Often called Vermont’s most famous volcano, Mount Ascutney (elev. 3,144 feet, 958 m) stands as a prominent monadnock in the Connecticut River Valley. The mountain often serves as an inspirational landmark, as it does when viewed from locations throughout the valley including the Saint-Gaudens National Historic Site (Walsh, 2017). The Ascutney Mountain igneous complex (Ratcliffe and others, 2011) consists of several mafic to felsic nested plutons including gabbro-diorite exposed at Little Ascutney to the west, and the Ascutney Mountain stock composed of syenite, granite, and related volcanic rocks underlying the main summit to the east (Fig. 1) (Schneiderman, 1989, 1991). Foland and Faul (1977) and Foland and others (1985) dated the gabbro-diorite complex at 125.5 to 122.2 Ma by K-Ar on biotite and by whole rock Rb/Sr, and dated the syenite-granite complex at 123.2 to 121.4 Ma by K-Ar on biotite. During the field trip we will visit the host rocks south of the mountain and the main rocks types of the Ascutney Mountain stock exposed near the summit and along the Mount Ascutney toll road. Mount Ascutney is the classic location where Daly (1903) discussed the evidence for piecemeal stoping as a pluton emplacement mechanism. This theory was later modified to favor cauldron subsidence, or ring-fracture stoping, as an alternative mode of emplacement (Chapman and Chapman, 1940). Our new mapping (Walsh and others, in press), which supersedes an earlier provisional study (Walsh and others, 1996a, b), supports the cauldron subsidence model, and shows that the main Ascutney Mountain stock is a funnel shaped composite pluton in agreement with geophysical data (Daniels, 1990). This field guide will primarily highlight the results of the new geologic mapping. This field guide is modified from a field trip presented in 2017 (Walsh, 2017). Additional stops have been added to examine the host rocks in the region south of the Ascutney Mountain stock. Two hikes are planned as part of this trip. Other NEIGC field trip guides to Mount Ascutney include Stoiber (1954) and Schneiderman (1988).

Vermont↗
USGS1997

Structure and kinematics of a complex impact crater, Upheaval Dome, southeast Utah

Two vastly different phenomena, impact and salt diapirism, have been proposed for the origin of Upheaval Dome, southeast Utah. Detailed geologic mapping, seismic refraction data, and the presence of shock metamorphosed rocks indicate that the dome originated by collapse of a transient cavity formed by impact. Evidence is: (1) the occurrence of a lag deposit of rare impactites, (2) fan-tailed fracture surfaces (shatter surfaces) and rare shatter cones are present near the center of the structure, (3) the top of the underlying salt horizon is at least 500 m below the surface at the center of the dome and there are no exposures of salt or associated rocks of the Paradox Formation in the dome to support the possibility that a salt diapir has ascended through it, (4) sedimentary strata in the center of the structure are pervasively imbricated by top-toward-the-center thrust faulting and are complexly folded as well, (5) top-toward-the-center normal faults are found at the perimeter of the structure, and 6) clastic dikes are widespread. We show that the dome formed mainly by centerward motion of rock units along listric faults. Outcrop-scale folding and upturning of beds, especially common in the center, are largely a consequence of this motion. We have also detected some centerward motion of fault-bounded wedges resulting from displacements on subhorizontal faults that conjoin and die out within horizontal bedding near the perimeter of the structure. The observed deformation corresponds to the central uplift and the encircling ring structural depression seen in complex impact craters.

Utah↗
USGS1950

Fifth special report of the Hawaiian Volcano Observatory of the Hawaiian Volcano Research Association and the U.S. Geological Survey: Abrasion hardness

After reviewing the work of sclerometry, this paper shows that yielding and relative softness are the mechanical basis of what should be called malacometry. The experiments have been made with diamond drills, ring cuts, end millers and grinding wheels. Auerbach's "limited scope of the Mohs list" is quantitatively confirmed. The wear of diamonds is examined. A program is carried out, for rotary or annular abrasion by diamond under three applications of energy, each progressively slower. A selected commercial talc is the control substance of softness value 100. The instruments used are synchronous motors, drill presses, wheel grinders, and watchmaker lathes. Some 200 minerals, woods, metals, glasses and plastics were originally measured. Hardness tables and curves are shown for comparison with volumetric abradability. For a Mohs succession the softer substances abrade relatively more under higher energy of contact friction, and any one substance shows higher relative values under lower energy of attrition; in other words, under slower scratching. An artificially cut diamond octahedron gives more consistent results than a natural crystal, under light pressures. Standard successions of relative abradability measurements do not hold good under different energies of attack. Functions of plasticity, brittleness, cleavage, powder lubricity, ductility and the like introduce various anomalies, and constancy of pressure varies with variable yielding. The supposition that rhythmic instrumental abrading will hold its mechanical constants, while the substance attacked yields in accord with its own surface molecular mobility relative to a control substance, is only approximately true. At low energies the approximation is better than at high, but at high speeds the wear of tool is less. Hence the advantage of using with slow speed a replaceable tool. Substances of different categories such as steels and woods, differ in behavior from minerals. The Mohs System has the great advantage of extending the controls from mineral to mineral up through the whole scale, and is purely qualitative. It is not numerically quantitative at all in terms of equal units. A principal result of this investigation is that 80 per cent of the Mohs Scale, Numbers 3 to 10, are by common consent within 1 per cent of a malacometric scale numbered 1 to 100. The scientists who determined this relation were the sclerometry investigators of the nineteenth century, who mistakenly thought that the wide intervals of sclerometry are between the hard minerals. They used the reciprocals of the measures of yielding. The simple scratch tester finally arrived at is quite different from the instruments of Parts II and III. It eliminates diamond drilling, retains the Mohs controls and utilizes a dental grinding wheel and a modern low speed motor. The object of this research has been to design a simple instrument for many uses, especially for the mechanic's shop. It is planned for manufacture at an early date. The author is indebted to Dr. Earl Ingerson, Chief, Geochemistry and Petrology Branch, for critical correction and approval of this paper, by authority of the Director, U. S. Geological Survey.

Report of the Hawaiian Volcano Observatory↗
USGS1977

Cauldron subsidence near Mount Lewis, Nevada: A misconception

The map and interpretation of the geology of the Mount Lewis quadrangle, northern Shoshone Range, Nev., contained in U.S. Geological Survey Professional Paper 465 (1965) have recently been criticized and reinterpreted by C. T. Wrucke and M. L. Silberman in Professional Paper 876 (1975). I contend, however, that the reinterpretation ignores much cogent evidence and is quite inconsistent with the geometric disposition of the rocks. No justification exists for postulating a caldera. The faults considered by Wrucke and Silberman to constitute the bounding faults of a caldera hence normal faults downthrown toward the "caldera" are in part nonexistent, in part a strike-slip fault formed concurrently with the Roberts thrust fault in Devonian and Mississippian time, and in part a listric thrust branching into the hanging wall of the main thrust. In short, the two real faults of Wrucke and Silberman's postulated caldera ring are about 200 million years older than the Oligocene volcanic rocks dated by Wrucke and Silberman. The paucity of dikes associated with the faults is thus readily understood, whereas it would be highly anomalous were the faults defining a caldera. The evidence for our thrust-fault interpretation was presented in the text, map, and sections of Professional Paper 465; further detail is included here. The evidence is clear and unequivocal: no caldera is here present.

Nevada↗
USGS2011

Hotspot: The Snake River geothermal drilling project - An overview

The Snake River volcanic province (SRP) overlies a thermal anomaly that extends deep into the mantle; it represents one of the highest heat flow provinces in North America, and an area with the highest calculated geothermal gradients. This makes the SRP one of the potentially highest producing geothermal districts in the United States. Elevated heat flow is typically highest along the margins of the topographic Snake River Plain and lowest along the axis of the plain, where thermal gradients are suppressed by the Snake River aquifer. Beneath this aquifer, however, thermal gradients rise again and may tap even higher heat flows associated with the intrusion of mafic magmas into a geophysically-imaged mid-crustal sill complex. The primary goal of this project is to evaluate geothermal potential in three distinct settings: (1) the high sub-aquifer geothermal gradient associated with the intrusion of mafic magmas and the release of crustal fluids from the associated wall rocks, (2) the valley-margin settings where surface heat flow may be driven by the up-flow of hot fluids along buried caldera ring-fault complexes, and (3) a more traditional fault-bounded basin with thick sedimentary cover. All settings are found within the central or western Snake River Plain and represent previously untested targets for geothermal exploration. Our first drill site tests the extent of geothermal resources along the axis of the plain, beneath the Snake River aquifer, in an area where elevated groundwater temperatures imply a significant flux of conductive or advective heat flow from below. Our second drill site assesses the geothermal potential of up-flow zones along a buried caldera margin, in an area of known geothermal potential (Twin Falls geothermal district). Further studies will include seismic reflection-refraction surveys, gravity-magnetic surveys, and downhole geophysical logs.

Idaho↗
USGS2023

Characterizing historic streamflow to support drought planning in the upper Missouri River basin

This project combined tree-ring based paleo and modern climate and hydrologic research aimed at understanding the primary influences on drought risk and water reliability in basins critical for western U.S. water resources. New paleohydrologic datasets and analyses were developed and applied to contextualize future streamflow projections and address specific water management questions. These questions centered around optimizing future water management protocols for numerous objectives ranging from improving agricultural water allocation during drought while maintaining instream flows for aquatic ecosystem health, to the testing of operations across large river systems with complex infrastructure critical for downstream flood control, navigation, and hydropower generation. USGS scientists worked closely with the Bureau of Reclamation to estimate both past and future drought risk at key management locations throughout the Missouri basin, the Milk and St. Mary River system, and across the major managed river systems in the western United States. These efforts provided a roadmap for future water management strategies under changing climate and water supply conditions, which are detailed in Reclamation’s newly completed Missouri Headwaters Basin Study, the 2021 SECURE Water Act Report, and the forthcoming update of the St. Mary and Milk Rivers Basin Study. Among the major scientific findings to emerge was a new understanding of the long-term (1200-year) history of drought variability for the Missouri River, which highlighted the unusual severity of the early 2000s drought across the Rocky Mountain headwaters and adjacent high plains. By combining the extended drought record with extensive modern and paleoclimate records, we document how warming exacerbates severities of naturally occurring droughts, with recent decades defined by “hot” droughts and the 2000s (2001-2010) drought ranking as the most severe event in 1200 years. Increasingly severe drought events such as this strain already over-allocated water resources that multiple sectors of society depend heavily upon.

upper Missouri River basin↗
USGS2023

Hydroclimate and fire paleorecords across the southern Rockies and Colorado Plateau over the common era

The southwestern US has been experiencing a severe drought and increased fire activity over the past two decades, affecting people’s health, homes, and businesses. Many individual fires occurring in the Southwest are the most severe in recorded history both in terms of dollars of damages as well as in fire extent. It is essential to be able to place the present drought and fires into the context of the current changing climate as well as in the framework of climate variability and human activity over centennial to millennial timescales. Dendrochronology can determine both the seasonality of fires as well as changes in precipitation. Charcoal, pollen, and the biomarkers levoglucosan, mannosan, and galactosan can help determine fire activity and the type of burned vegetation. People have controlled and utilized fire in the southwestern US for thousands of years. While proxies cannot yet determine if people ignited a specific fire, fecal sterols can determine if people were within an individual watershed. Here, we examine the strengths and weaknesses of using high-resolution tree-ring data in conjunction with biomarkers in ice and lake cores from the southwestern US to study interactions between changes in hydroclimate, fires, and human activity.

Conference Paper↗
USGS2025

Predation of Lost River and Shortnose suckers by piscivorous colonial waterbirds in the Upper Klamath Basin: An analysis of predation effects during 2021–2023

Previously published research indicated that predation by piscivorous colonial waterbirds in the Upper Klamath Basin was a source of mortality for Lost River suckers ( Deltistes luxatus ) and Shortnose suckers ( Chasmistes brevirostris ), including mortality of Sucker Assisted Rearing Program (SARP) fish. Avian predation on recently released Chinook Salmon ( Oncorhynchus tshawytscha ) in the Upper Klamath Basin has not been studied. To provide fisheries managers with the most up-to-date information, we estimated predation rates on passive integrated transponder tagged (PIT) suckers and Chinook Salmon by breeding colonies of American White Pelicans ( Pelecanus erythrorhynchos ), Double-crested Cormorants ( Nannopterum auritum ), Caspian Terns ( Hydroprogne caspia ), California Gulls ( Larus californicus ), Ring-billed Gulls ( L. delawarensis ), Great Blue Herons ( Ardea herodias ), and Great Egrets ( A. alba ) during 2021–2023. Predation rate estimates were variable depending on the fish species, age-class (juvenile, adult), waterbody (Upper Klamath Lake, Clear Lake Reservoir, Sheepy Lake), and year. Results indicated that avian predation rates were highest on juvenile suckers and on suckers in Clear Lake Reservoir. SARP fish released in the spring/summer were more likely to be consumed by breeding birds than those released in the fall/winter, although the number of fish released in the fall/winter that survived to the spring/summer was unknown and could bias predation estimates low. Predation rate estimates on Chinook Salmon varied by year, release timing (spring/summer, fall/winter), release location (Upper Klamath Lake, Klamath River), and age-class (subyearling, yearling). The location and size of colonies were also highly variable depending on the bird species, colony location, and year. Future research could focus on identifying biotic and abiotic factors associated with sucker susceptibility to piscivorous colonial waterbirds and determining to what degree avian predation limits the recovery of suckers in the Upper Klamath Basin.

California, Oregon↗
USGS2025

Predation of Lost River and Shortnose Suckers by piscivorous colonial waterbirds in the Upper Klamath Basin: An analysis of predation effects in 2024

The recovery of endangered fish requires an understanding of the sources of mortality that regulate population dynamics. We estimated avian predation rates on passive integrated transponder tagged (PIT) adult and juvenile Lost River Suckers ( Deltistes luxatus ), Shortnose Suckers ( Chasmistes brevirostris ), Klamath Largescale Suckers ( C. snyderi ), and juvenile Chinook Salmon ( Oncorhynchus tshawytscha ) by breeding colonies of American White Pelicans ( Pelecanus erythrorhynchos ), Doublecrested Cormorants ( Nannopterum auritum ), Caspian Terns ( Hydroprogne caspia ), California Gulls ( Larus californicus ), Ring-billed Gulls ( L. delawarensis ), Great Blue Herons ( Ardea herodias ), Great Egrets ( A. alba ), and Black-crowned Night Herons ( Nycticorax nycticorax ) in the Upper Klamath Basin (UKB) in 2024. Results from 2024 contribute to a long-term (2009–2023) avian predation dataset in the UKB. The largest numbers of pelicans (1,422 breeding adults), terns (610 adults), and gulls (3,872) were nesting on islands in Clear Lake Reservoir. The largest number of cormorants (787 adults) were on an island in Sheepy Lake, and the largest numbers of herons (450 adults) were at arboreal sites adjacent to Upper Klamath Lake. Predation rate estimates in 2024 were highly variable depending on the fish species, ageclass (juvenile, adult), waterbody (Upper Klamath Lake, Clear Lake Reservoir, Sheepy Lake, Tule Lake), and release or reencounter date for juveniles (spring/summer or fall/winter). Results indicated that avian predation rates were the highest on wild and hatchery juvenile suckers. An estimated 19.4% (95% credible interval = 15.7–24.0) of Sucker Assisted Rearing Program (SARP) hatchery fish, released or reencountered during the spring and summer, were consumed by the colonies included in the study. Predation was also appreciable on wild juvenile suckers in Clear Lake Reservoir (13.4% [9.9–17.7]) and SARP juvenile suckers released or reencountered in Upper Klamath Lake in the fall/winter (11.2% [9.6 13.2]). Predation rate estimates on adult suckers were significantly lower than those of juvenile suckers, with predation ranging from 0.3% (0.2–0.7) to 2.6% (1.9–3.5) in adult Lost River Suckers in Upper Klamath Lake and adult Shortnose Suckers-Klamath Largescale Suckers in Clear Lake Reservoir, respectively. Predation rate estimates on juvenile Chinook Salmon, which were released in fall/winter, were 2.9% (2.2–3.6). Pelican (312 adults) and cormorant (301 adults) colonies in Upper Klamath Lake, however, were not scanned for fish PIT tags following breeding season, resulting in minimum estimates of predation on UKB fishes (both suckers and Chinook Salmon) in 2024. Future research could examine what biotic and abiotic factors best explain variation in predation and to what degree predation limits sucker survival using the long-term dataset that has been complied to date.

California, Oregon↗
USGS2024

Assessing trade-offs in developing a landscape-scale nest monitoring programme for a threatened shorebird

Effective monitoring of wildlife species requires thorough planning and development of survey programmes that can address management and conservation objectives. Decisions about monitoring programmes include where to survey, survey design and how much effort to allocate at survey sites are typically predicated on limited budgets and available resources. When the scope of inference requires monitoring on a broad spatial scale, predictions of habitat distribution or suitability may be useful for identifying potential survey sites. We focused on a threatened but widely distributed shorebird, the piping plover ( Charadrius melodus ), which is actively monitored across some, but not all of its range. Our objective was to use piping plover habitat distribution maps, which vary annually, to assess the effectiveness of multiple monitoring programme scenarios and their associated costs. In the breeding range, efforts to improve productivity for species of conservation concern often focus on improving probabilities of nest survival. Consequently, collecting adequate nesting data is crucial for obtaining accurate and precise estimates of nest survival and for evaluating the effectiveness of management actions. By simulating the nest monitoring process, we evaluated how much area, where and how often to survey each site when estimating nest survival and detecting effects of potential management actions. As expected, precision increased and bias decreased around nest survival estimates with greater survey coverage and nest visit frequency. We also identified monitoring programmes with negative net values where survey costs outweighed statistical benefits. Although we applied our simulation framework to evaluate nest monitoring designs for piping plovers, it could be extended to assess whether different monitoring programmes can detect changes in the distribution of other species or occupancy of habitats over time.

Ecological Solutions and Evidence↗
USGS2025

Not all spatially structured populations are metapopulations: Re-examining paradigms for a threatened shorebird

For at-risk species, understanding population vital rates is imperative for developing informed conservation strategies and population models. Managers often assume that species that are spatially distributed among patches of suitable habitat meet the criteria of a metapopulation. Metapopulation dynamics are determined not only by within-patch birth and death processes but also by between-patch dispersal movements of individuals that are infrequent but critical to maintaining population viability across space and time. To conserve and manage such species, an understanding of all these vital rates, including connectivity, is required. The degree to which the northern Great Plains piping plover ( Charadrius melodus ) breeding population functions as a metapopulation depends, in part, on the rate of movement among patchily distributed breeding areas. Here, we examined annual adult survival and breeding dispersal probabilities for 2582 individuals at two spatial scales within the northern Great Plains piping plover breeding population between 2014 and 2019. Inconsistent with a metapopulation structure, annual survival varied minimally among breeding regions but did vary across years. We also found that breeding dispersal probabilities were temporally variable, high, and unbalanced at both spatial scales examined, suggesting high connectivity in contrast to metapopulation dynamics. Further, we detected context-dependent effects of reproductive success on dispersal decisions. Individuals were more likely to disperse from the northern Missouri River to the US Alkali Wetlands following nest failure due to inundation or severe storms (including in the year prior to dispersal), whereas dispersal from the US Alkali Wetlands to the northern Missouri River decreased following successful nest attempts. Individuals also decreased dispersal from the US Alkali Wetlands to the northern Missouri River in response to renesting attempts in both the year of interest and the year prior to dispersal. Our results contradict the paradigm that northern Great Plains piping plovers are structured as a metapopulation and instead suggest a patchily distributed, likely panmictic, population. Our findings have implications for the conservation and management of this listed species and are also a general reminder that in the absence of robust knowledge of movement, spatial variation in birth and death processes across patches should not be conflated with a metapopulation structure.

Montana, North Dakota, South Dakota↗
USGS2024

The cost of self-defense: Browsing effects in the rare plant species Salix arizonica

Coevolution between plants and their animal predators has led to diverse defensive adaptations. Multiple theories of defense propose that there are resource allocation costs associated with producing chemical defenses. One leading hypothesis, optimal defense theory (ODT), suggests that natural selection will result in the allocation of resources to defenses that optimize the cost-to-benefit ratio between defense and other functional processes. The population decline of the rare subalpine wetland species, Arizona willow ( Salix arizonica ), has been attributed to various biotic and abiotic factors, with browsing from wild and domestic ungulates as a significant concern for at least three decades. In a field experiment using natural populations, we compare the relationship between phytochemical defense and height in Arizona willows with and without long-term protection from browsing via browse exclosures. Consistent with the predictions of ODT, individuals with physical protection from ungulate browsing for multiple years had significantly lower phenolic glycoside (PG) concentrations and increased plant height compared to unprotected individuals. A similar pattern was found across all individuals, whereby total PG concentration and height were negatively correlated. In a short-term experiment in natural populations, changes in levels of defense were not observed when plants received protection for only one growing season. The contrasting pattern of defense plasticity in response to long-term versus short-term physical protection suggests a differential plastic response in this long-lived species. Delayed reduction in PG concentration may serve as a benefit to avoid mismatches between environmental cues and responses. Our research sheds light on the intricate dynamics between plant-defense strategies, environmental pressures, and evolutionary adaptations in shaping plant–browser interactions.

Arizona, Colorado, New Mexico, Utah↗
USGS2022

Implications of habitat-driven survival and dispersal on recruitment in a spatially structured piping plover population

Natal survival and dispersal have important consequences for populations through the movement of genes and individuals. Metapopulation theory predicts either balanced natal dispersal among regions or source–sink dynamics, which can dramatically change population structure. For species reliant on dynamic, early-successional habitats, availability and location of habitat will shift from year to year, requiring primiparous individuals to locate an appropriate breeding habitat. We estimated hatch-year survival to adulthood and natal dispersal rates between two breeding groups of Northern Great Plains piping plovers ( Charadrius melodus ) from four cohorts ( n = 2669 total individuals; 2014–2017). Hatch-year survival to adulthood was slightly higher for individuals hatched on the Missouri River than on the US Alkali Wetlands but declined over time. Individuals hatched on the US Alkali Wetlands were more likely to disperse to breed on the Missouri River (0.33 [0.20, 0.48]) than vice versa (0.17 [0.11, 0.24]). When more habitat was available at the natal site than in the prior year, natal dispersal rates increased. However, despite higher recruitment rates as a result of higher natal fidelity, the Missouri River showed lower total recruitment with a declining trend in the number of recruits, largely due to differences in abundance between breeding groups. Overall, unbalanced, high natal dispersal rates within the Northern Great Plains indicate high connectivity among distinct regions with different water regimes on the Missouri River and on the US Alkali Wetlands driven by fluctuating availability of habitat. Our results suggest that plovers in the Northern Great Plains take advantage of dynamic habitats where they are available in a broad geographic area, which is consistent with a spatially structured panmictic population rather than a true metapopulation, but further research on adult breeding dispersal is needed to clarify population structure.

North Dakota, South Dakota↗
USGS2023

Conspecific density and habitat quality affect breeding habitat selection: Support for the social attraction hypothesis

Breeding habitat selection is a critical component of the annual cycle because of its effect on fitness. Multiple theories of habitat selection can be differentiated by their responses to the quantity of habitat, conspecific density, and habitat quality. Here, we use network analysis to understand the characteristics of fine-scale breeding habitat selected by both immigrant and returning adult piping plovers ( Charadrius melodus ) to test five hypotheses of habitat selection. Between 2014 and 2019, we recorded 2034 uniquely marked adults breeding at 326 breeding locations with 1240 successive breeding events. Among adults, immigration events (i.e., individuals that moved to a new breeding location) were detected as often as fidelity to the same breeding location. We found support for the social attraction hypothesis for both immigrants and returners, indicating that adult plovers use social cues for settlement decisions. Adult plovers selected habitats with intermediate levels of conspecific density and high habitat quality, as assessed by con- and heterospecific nest survival, with no effect from the amount of available habitat. We also simulated the loss of breeding habitat and identified highly connected breeding locations, which occurred mostly on the riverine habitat type, which have important implications for habitat conservation for this listed species. Our results highlight the role of conspecifics at identifying high-quality breeding habitat regardless of whether individuals return to the same breeding site or immigrate to new areas.

North Dakota, South Dakota↗
USGS2021

Experimental evaluation of predator exclosures on nest, chick, and adult survival of piping plovers

Species of conservation concern often receive intensive management to improve vital rates and facilitate recovery. Piping plovers ( Charadrius melodus ) are federally listed in the United States and concerns over nest depredation have prompted widespread use of plover-permeable predator exclosures placed around nests (0.5–2-m radius). While effectiveness of exclosures for improving nest survival has been demonstrated, concerns remain about decreased chick survival (through predator cueing or density-dependent processes) or increased vulnerability of adults to predation (ambush as adult leaves exclosure). Either one of these concerns could demographically outweigh the benefits of increased nest survival. During 2014–2016, we conducted an experiment designed to evaluate survival of uniquely identified nests ( n = 418), chicks ( n = 453), and adults ( n = 367) at wetlands across the Northern Great Plains, USA. We assigned wetlands ( n 2014 = 26, n 2015 = 28, n 2016 = 25) into 2 groups: wetlands in which half of the nests received exclosures and wetlands in which none of the nests received exclosures. Exclosed nests had greater cumulative survival (0.73 [85% CI = 0.70–0.77]) than unexclosed nests at treatment wetlands (0.58 [0.54–0.62]) or unexclosed nests at control wetlands (0.52 [0.49–0.56]). Survival to fledging was highest for chicks hatched from exclosed nests (0.51 [0.47–0.56]), and similar between chicks hatched from unexclosed nests at treatment (0.34 [0.30–0.39]) and control (0.37 [0.32–0.42]) wetlands. Cumulative survival of adults during incubation varied by exclosure status, but adults associated with exclosed nests (0.90 [0.88–0.93]) and unexclosed nests at treatment wetlands (0.89 [0.86–0.92]) had greater survival than those associated with unexclosed nests at control wetlands (0.75 [0.64–0.84]). Adult annual survival rates varied by year (0.79–0.95) but not by exclosure status. The positive influence of exclosures on nest survival was not offset by a reduction in chick or adult survival, indicating that exclosures are a viable tool for piping plover conservation.

Montana, North Dakota↗
USGS2021

Impacts of extreme environmental disturbances on piping plover survival are partially moderated by migratory connectivity

Effective conservation for listed migratory species requires an understanding of how drivers of population decline vary spatially and temporally, as well as knowledge of range-wide connectivity between breeding and nonbreeding areas. Environmental conditions distant from breeding areas can have lasting effects on the demography of migratory species, yet these consequences are often the least understood. Our objectives were to 1) evaluate associations between survival and extreme environmental disturbances at nonbreeding areas, including hurricanes, harmful algal blooms, and oil spills, and 2) estimate migratory connectivity between breeding and nonbreeding areas of midcontinental piping plovers ( Charadrius melodus ). We used capture and resighting data from 5067 individuals collected between 2002 and 2019 from breeding areas across the midcontinent, and nonbreeding areas throughout the Gulf of Mexico and southern Atlantic coasts of North America. We developed a hidden Markov multistate model to estimate seasonal survival and account for unobservable geographic locations. Hurricanes and harmful algal blooms were negatively associated with nonbreeding season survival, but we did not detect a similarly negative relationship with oil spills. Our results indicated that individuals from separate breeding areas mixed across nonbreeding areas with low migratory connectivity. Mixing among individuals in the nonbreeding season may provide a buffering effect against impacts of extreme events on any one breeding region. Our results suggest that understanding migratory connectivity and linking seasonal threats to population dynamics can better inform conservation strategies for migratory shorebirds.

Biological Conservation↗
USGS2025

The effects of forest harvesting on total and methylmercury concentrations in surface waters depend on harvest practices and physical site characteristics

Forest harvesting can lead to mercury (Hg) mobilization from soils to aquatic habitats and promote the transformation of inorganic Hg to highly neurotoxic and bioaccumulative methyl-Hg (MeHg). Multiple past studies reveal broad variation of stream water MeHg and total Hg (THg) concentrations responses to forest harvesting, which has confounded messaging to forest and resource managers. To advance beyond divergent and sometimes contradictory findings, we synthesize information for 23 previously studied catchments in North America and Fennoscandia, and compiled a uniform set of soil, landscape, and harvesting properties to identify forest management, riparian, and hillslope factors that influence responses of stream water MeHg and THg concentrations. From this synthesis, we found catchments with high soil moisture and organic soil layers > 100 cm to be at highest risk for disturbance-induced increases in MeHg formation after harvest, but not necessarily affecting concentrations of MeHg in stream waters. Instead, the combination of MeHg formation in soils along with factors that affect mobilization with runoff to streams most influenced how forest harvest affects MeHg concentrations in stream waters.

Environmental Science and Technology↗