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At least 595 records · Page 33Linked to original sources
USGS1999

Survival of greater white-fronted geese: Effects of year, season, sex, and body condition

Information regarding the magnitude and variation in survival rates is necessary for understanding the causes of large changes in population size. We examined survival of greater white-fronted geese (Anser albifrons frontalis) in the Pacific Flyway during 1979-82. The population declined by 75% in the decade preceding our study but was stable during our investigation. Annual survival of adults (0.749, SE = 0.045) was 7% higher than during an earlier study. We developed a simple population model which suggests that recent (1985-96) survival rates may be as much as 10% higher in adults than the 1979-82 rate, which corresponds to population increases observed since 1985. Survival of adult females varied seasonally; monthly survival during a period of winter when no hunting or migration occurred was higher (0.986, SE = 0.015) than monthly survival at other times (0.964, SE = 0.006). Survival of adult males varied among years and with a general seasonal trend inverse to that for females. An index of body condition was positively related to survival of adult females in fall and spring, but not for adult males or immature geese. Monthly survival of immatures was lower during their first hunting season (0.886, SE = 0.026) than during all subsequent seasons (0.963, SE = 0.007). Annual survival of immatures beginning 1 October, immediately before the hunting season, was 0.471. Corresponding variations in survival rates, population numbers, and hunting regulations suggest that hunting may have influenced survival in this population of greater white-fronted geese.

Journal of Wildlife Management↗
USGS2000

Distribution of recoveries of Steller's Eiders banded on the lower Alaska Peninsula, Alaska

Molting adult Steller's Eiders ( Polysticta stelleri ) were banded at Izembek Lagoon (1961-1998) and Nelson Lagoon (1995-1997) along the lower Alaska Peninsula to determine breeding distribution and movements. Of 52,985 Steller's Eiders banded, 347 were recovered. The overall low recovery rate may not be indicative of harvest levels but may be due to low reporting rates of bands. Almost all recoveries during summer were from Russia and recovery rates did not differ between sexes. We found no evidence that Steller's Eiders molting in specific locations were more likely to be recovered in specific geographic locations in Russia. Our recoveries suggest that Steller's Eiders molting along the Alaska Peninsula were from Russian breeding sites and from remnant breeding populations in Alaska.

Alaska↗
USGS2003

Toggling of seismicity by the 1997 Kagoshima earthquake couplet: A demonstration of time-dependent stress transfer

Two M ??? 6 well-recorded strike-slip earthquakes struck just 4 km and 48 days apart in Kagoshima prefecture, Japan, in 1997, providing an opportunity to study earthquake interaction. Aftershocks are abundant where the Coulomb stress is calculated to have been increased by the first event, and they abruptly stop where the stress is dropped by the second event. This ability of the main shocks to toggle seismicity on and off argues that static stress changes play a major role in exciting aftershocks, whereas the dynamic Coulomb stresses, which should only promote seismicity, appear to play a secondary role. If true, the net stress changes from a sequence of earthquakes might be expected to govern the subsequent seismicity distribution. However, adding the stress changes from the two Kagoshima events does not fully capture the ensuing seismicity, such as its rate change, temporal decay, or migration away from the ends of the ruptures. We therefore implement a stress transfer model that incorporates rate/state friction, in which seismicity is treated as a sequence of independent nucleation events that are dependent on the fault slip, slip rate, and elapsed time since the last event. The model reproduces the temporal response of seismicity to successive stress changes, including toggling, decay, and aftershock migration. Nevertheless, the match of observed to predicted seismicity is quite imperfect, due perhaps to inadequate knowledge of several model parameters. However, to demonstrate the potential of this approach, we build a probabilistic forecast of larger earthquakes on the expected rate of small aftershocks, taking advantage of the large statistical sample the small shocks afford. Not surprisingly, such probabilities are highly time- and location-dependent: During the first decade after the main shocks, the seismicity rate and the chance of successive large shocks are about an order of magnitude higher than the background rate and are concentrated exclusively in the stress triggering zones. Copyright 2003 by the American Geophysical Uion.

Journal of Geophysical Research B: Solid Earth↗
USGS2008

Seasonal survival of radiomarked emperor geese in western Alaska

The population of emperor geese ( Chen canagica ) in western Alaska, USA, declined by >50% from the 1960s to the mid‐1980s and has increased only slightly since. Rates of population increase among arctic geese are especially sensitive to changes in adult survival. Improving adult survival in seasons or geographic areas where survival is low may be the best means of increasing the emperor goose population. We monitored fates of 133 adult female emperor geese that were radiomarked with surgically implanted very high frequency or satellite radiotransmitters from 1999 to 2004 to assess whether monthly survival varied among years, seasons, or geographic areas. Because of uncertainties in determining whether a bird had died based on the radio signal, we analyzed 2 versions of the data. One version used conservative criteria to identify which birds had died based on radio signals and the other used more liberal criteria. In the conservative version of the data we detected 12 mortalities of emperor geese, whereas in the liberal interpretation there were 18 mortalities. In both versions, the models with greatest support indicated that monthly survival varied seasonally and that compared to most seasons estimated monthly survival was lower (φ = 0.95–0.98) in May and August when emperor geese were mainly on the Yukon‐Kuskokwim Delta. From 44% to 47% of annual mortality occurred in those months. Estimated monthly survival was higher (φ = 0.98–1.0) from September through March when emperor geese were at autumn staging or wintering areas and in June and July when birds were nesting, rearing broods, or molting. Estimated annual survival was 0.85 (95% CI = 0.77–0.92) in the best‐supported model when we used conservative criteria to identify mortalities and 0.79 (95% CI = 0.74–0.85) under the best model using liberal mortality criteria. Lower survival in August and May corresponded to periods when subsistence harvest of emperor geese was likely highest. Managers may be able to most effectively influence population growth rate of emperor geese by reducing subsistence harvest on the Yukon‐Kuskokwim Delta in May and August.

Alaska↗
USGS1978

Regional gravity and magnetic anomalies in the eastern Snake River Plain, Idaho

Over the eastern Snake River Plain, the Bouguer gravity anomaly and the magnetic intensity are, in general, high. In detail, both the gravity and the magnetic anomalies are a complex of highs and lows, in contrast to the simpler anomalies over the western Snake River Plain. The broad gravity high associated with the eastern Snake River Plain cannot be produced by a dense mass at shallow depth under the plain, but must be produced either by a deep feature under the plain or by a broader, shallower feature extending well beyond the plain. The high could be produced by a thinning of the crust under the plain by 4.5 to 7 kilometers. The data suggest that the Cenozoic rocks of the plain are underlain by rocks that have density and magnetization similar to the density and magnetization of the pre-Cenozoic rocks north and south of the plain. The data do not suggest rifting of the upper crust such as is inferred for the western Snake River Plain. The plain is in approximate isostatic equilibrium with adjoining regions to the north and south and thus contrasts with the adjoining areas where the basin-and-range topography is not in isostatic equilibrium. The local gravity anomalies on the plain are probably produced by variations in the thickness of Cenozoic rocks, but the wavelength of the anomalies is about twice that of the basin-and-range structural features in areas adjoining the plain. The gravity expression of basin-and-range structural features does not extend far onto the plain. Magnetic anomalies on the plain are produced by Cenozoic volcanic rocks.

Idaho↗
USGS1978

Wood River mining district, Idaho - intrusion-related lead-silver deposits derived from country rock source

Lead-silver deposits in the Wood River mining district occur in shear zones in hornfelsed argillite of the Devonian Milligen Formation near granitic plutons and under the Wood River thrust fault. The principal ore minerals are argentiferous galena and sphalerite; siderite is the principal gangue. The δ 34 S values of the sulfide minerals range from +2.2 to +15.0 permil, indicating that the sulfur had a shallow crustal source. Δ 34 S values between sphalerite and galena range from +2.3 to +3.4 permil, corresponding to sulfur isotope temperatures between 280° and 182 °C. Hydrothermal barite has a δ 34 S of +13.2 permil. Lead isotope ratios are radiogenic, also pointing to a shallow crustal source. Quartz gangue has δ 18 O of +16.4 permil and a calculated δ 18 O H20 at 270°C of +8.4 permil. This value is reasonable for a hydrothermal fluid that had reached equilibrium with the argillite country rock. The siderite gangue has δ 18 O and δ 13 C values of +14.0 and -5.5 permil, respectively. Fluid inclusions have homogenization temperatures of 244°-307°C and average 270°C. Freezing-stage measurements ranged from -1.85 to -2.8°C, suggesting salinities of 3.2 to 4.8 weight percent. The δD values of inclusion fluid in ore and gangue minerals are -110 to -120 permil. The geology, isotope, and fluid-inclusion data are consistent with a model of hydrothermal systems of meteoric water in faulted and shattered Paleozoic rocks near plutonic masses. This environment permitted deep circulation of the hydrothermal fluids, which dissolved the metals and sulfur from the Paleozoic host rocks and deposited ore in favorable beds or structures under the regional Wood River thrust fault.

Idaho↗
USGS1974

The effects of the Hurricane Agnes flood on channel geometry and sediment discharge of selected streams in the Susquehanna River basin, Pennsylvania

The Hurricane Agnes flood seems to have hardly changed the channel geometry of the Pennsylvania streams studied in this report. The 10 sites studied generally showed that the width of the stream channels had been changed little by the flood and that streambed altitudes had been lowered less than a foot (0.3 m). The velocity of the streams at a given discharge had decreased. In comparison, the sediment deposited by the December 1964 flood in northwestern California commonly raised the streambed altitudes several feet. The differences in the effects of the two floods may have been produced by the availability of sediment for transport, by the relative size of sediment carried in suspension or bedload, or by the relative magnitudes of the floods.

Pennsylvania↗
USGS1975

A typical cross section based on magnetic data of lower and middle Keweenawan volcanic rocks, Ironwood area, Michigan

A north-trending aeromagnetic profile of a sequence of east-striking Keweenawan volcanic rocks near Ironwood, Mich., can be matched to a calculated profile over a model consisting of a series of dipping layers. (The dips were those measured by H. A. Hubbard along the north-trending valley of the Black River.) Remanent and induced magnetizations of 39 oriented cores from the Black River valley were determined by K. G. Books; felsite from Chippewa Hill and basalt from Algonquin Falls of middle Keweenawan age have normal Keweenawan magnetization and lower Keweenawan Powder Mill rocks have reverse magnetization. In the model these magetizations were assigned to 26 layers which alternated with very weakly magnetized layers. The best match of the calculated composite anomalies of remanent and induced magnetization and the aeromagnetic profile occurs if a deeper block of steeply dipping Powder Mill rocks is assumed to underlie the middle Keweenawan flows.

Michigan↗
USGS1975

Age of volcanism, intrusion, and mineralization in the Thomas Range, Keg Mountain, and Desert Mountain, western Utah

Twenty-six new age determinations by the fission-track method establish a chronology for volcanism, intrusion, and mineralization in the Thomas Range, Keg Mountain, and Desert Mountain, in western Utah. The fission-track ages confirm D. R. Shawe's three-fold classification of igneous rocks. The oldest group of rocks consists of flows, agglomerates, and some ash-flow tuffs that were deposited 38-39 m.y. ago. The middle group contains widespread rhyolitic ash-flow tuffs that originated from local volcanic centers 30-32 m.y. ago. A dike emplaced along the probable ring-fracture zone of the Keg caldera about 31 m.y. ago indicates that caldera collapse occurred soon after eruption of ash-flow tuffs. Rocks believed to belong-to the middle group also were intruded by the quartz monzonite of Desert Mountain 27-30 m.y. ago. Little or no igneous activity took place within the next 20 m.y., during which time the region was strongly broken by Basin-and-Range faulting. Rhyolites of the youngest group were extruded 8-10 m.y. ago in the Keg Mountain area and 6-7 m.y. ago in the Thomas Range. The beryllium-fluorite mineralization at Spor Mountain occurred after the rhyolitic volcanism in the Thomas Range.

Utah↗
USGS1973

Zeolites in the Miocene Briones Sandstone and related formations of the central Coast Ranges, California

Authigenic zeolites present in the generally tuffaceous Miocene Briones Sandstone and related formations of the central Coast Ranges of California indicate three stages of diagenetic history: (1) Initial alteration of pyroclastic materials to clinoptilolite (and montmorillonite) that is widely distributed in small amounts throughout the region. (2) Subsequent crystallization of heulandite followed by stilbite in fractures at a few places. (3) Widespread development of laumontite in only the southern part of the region, where the sandstone appears to have been downfolded and faulted to greater depths than elsewhere. Laumontite occurs both as pervasive cement of sandstone and as filling of fractures, and was produced through the reaction of interstitial solutions with other zeolites and with such major constituents of the sandstone as plagioclase, montmorillonite, and calcite at temperatures of 100° C or higher. Mordenite was found at only one locality, closely associated with clinoptilolite and opal. Analcite occurs in diverse settings, and its relation to the other zeolites is obscure. Sparry calcite and coexisting stilbite, laumontite, or analcite in veins seem to make up nonequilibrium assemblages.

California↗
USGS1977

A method for adjusting values of Manning's roughness coefficient for flooded urban areas

A method is presented for adjusting values of Manning's roughness coefficient for flooded urban areas on the basis of the density of buildings on a flood plain and verified roughness coefficients for natural conditions. An urban roughness coefficient can be calculated to emulate the water-surface profiles to within 0.06 meter for depths of flow less than 0.6 meter and plus or minus 10 percent for depths between 0.6 and 2 meters.

Journal of Research of the U.S. Geological Survey↗
USGS1977

Feasibility and technology for making remote measurements of solutes in water

An indepth evaluation of the available technology in the field of laser-Raman spectroscopy indicates that a TV-type detector, a single monochromator with a holographic grating, an entrance slit filter blocking the Rayleigh light, and a pulsed laser coupled to signal averaging electronics is the best combination of commercial equipment that is presently available for building a remote water-quality sensor. The resultant sensor would be capable of measuring oxyanions in water at concentrations from 10 to 50 milligrams per liter at distances from ground level to 30 meters above the sample. The main interferences would be ambient light, bioluminescence, and natural fluorescence, all of which are minimized when taking advantage of the signal generating and readout capability contained in this equipment package.

Journal of Research of the U.S. Geological Survey↗
USGS2014

Defining ecological and economical hydropoweroperations: a framework for managing dam releasesto meet multiple conflicting objectives

Hydroelectric dams are a flexible source of power, provide flood control, and contribute to the economic growth of local communities through real-estate and recreation. Yet the impoundment of rivers can alter and fragment miles of critical riverine habitat needed for other competing needs such as downstream consumptive water use, fish and wildlife population viability, or other forms of recreation. Multiple conflicting interests can compromise progressive management especially with recognized uncertainties related to whether management actions will fulfill the objectives of policy makers, resource managers and/or facility owners. Decision analytic tools were used in a stakeholder-driven process to develop and implement a template for evaluation and prediction of the effects of water resource management of multiple-use systems under the context provided by R.L. Harris Dam on the Tallapoosa River, Alabama, USA. The approach provided a transparent and structured framework for decision-making and incorporated both existing and new data to meet multiple management objectives. Success of the template has been evaluated by the stakeholder governing body in an adaptive resource management framework since 2005 and is ongoing. Consequences of management of discharge at the dam were evaluated annually relative to stakeholder satisfaction to allow for adjustment of both management scenarios and objectives. This template can be applied to attempt to resolve conflict inherent in many dam-regulated systems where management decisions impact diverse values of stakeholders.

Journal of Energy Challenges and Mechanics↗
USGS2001

Topography and flooding of coastal ecosystems on the Yukon-Kuskokwim Delta, Alaska: Implications for sea level rise

We measured surface elevations, stage of annual peak flooding, and sedimentation along 10 toposequences across coastal ecosystems on the Yukon-Kuskokwim (Y-K) Delta in western Alaska during 1994-1998 to assess some of the physical processes affecting ecosystem distribution. An ecotype was assigned to each of 566 points, and differences in elevations among 24 ecotypes were analyzed within individual toposequences and across the 40 x 40-km study area. Elevations of vegetated ecotypes along the longest toposequence rose only ~1 m over a distance of 7.5 km, and mean elevations of most ecotype across the study area were within 0.5 m of mean higher-high water (1.47 m). During 1994 to 1998, monitoring of annual peak stage using crest gauges revealed flooding from the highest fall storm surge reached 2.58 m (1.11 m above mean higher-high tide). In each year, only the highest surface was unaffected by flooding. Mean annual sedimentation rates for the various ecotypes were 8.0 ram/y on tidal flats, 1.4 to 3.8 mm/y on the active floodplain, 0.1-0.2 mm/y on the inactive floodplain, and 0 mm/ on the abandoned floodplain. If sea levels in the Bering Sea rise ~0.5 m by 2100, as predicted by some on a global basis, large portions of the coastal margin of the delta could be regularly inundated by water during high tides, and even the highest ecotypes could be affected by storm surges. Predicting the extent of future inundation is difficult, however, because of the changes in the ground-surface elevation through sedimentation, organic matter accumulation, and permafrost development.

Alaska↗
USGS1990

Effects of neck bands on the behavior of wintering greater white-fronted geese

A ctivity budgets of adult Greater White-fronted Geese ( Anser albifrons frontalis ) with and without neck bands during the non-breeding season revealed that geese with neck bands spent more time preening than geese without neck bands while at foraging sites, but not while at roosting sites. Neck-banded and control geese spent equal time in other important activities (alert, feeding, sleeping, locomotor activities, flying, or social interactions) while at both foraging and roosting sites. Neck-banded geese apparently compensated for the increase in preening activity by reducing the amount of time spent in alert postures relative to control geese (23.9 vs. 28.6%), although the decrease was not significant (P = 0.106). There was a significant negative relationship (P = 0.038) between the length of time a goose had worn a neck band and the amount of time spent preening while at roost sites. After a short acclimation period, neck bands probably have minimal effect on the activity of wintering Greater White-fronted Geese.

Alaska, California↗
USGS1992

Intraspecific variation in egg shape among individual emperor geese

Within-clutch variability in shape of 1743 eggs from 301 nests of Emperor Geese ( Chen canagicus ) laid over a 5-yr period was measured. Individual females laid similar shaped eggs in successive years, and eggs among clutches within females could not be distinguished. Cluster analysis correctly identified 69.9% of 136 known conspecific parasitic eggs. Repeatability estimates of elongation (0.73), sphericity (0.72), maximum width (0.69) and radius of the point (0.68) were high and similar to repeatability estimates of egg mass and volume of other species. Although width, volume and area measurements varied inversely with spring population size, shape variables did not. The consistency in shape variables despite changes in egg size suggests that shape variables may be used to separate and identify individuals within and among years despite changes in the population that may result in changes in egg size. Differences in egg shape among eggs within a nest are viable criteria for identifying parasitic eggs, especially when used in conjunction with other methods.

Journal of Field Ornithology↗
USGS2017

Relationships among catch, angler catisfaction, and fish assemblage characteristics of an urban small impoundment fishery

Urban fisheries provide unique angling opportunities for people from traditionally underrepresented demographics. Lake Raleigh is a 38-ha impoundment located on the North Carolina State University campus in Raleigh. Like many urban fisheries, little is known about angler use and satisfaction or how angling catch rate is related to fish availability in Lake Raleigh. We characterized the recreational fishery and fish assemblage with concurrent creel and boat electrofishing surveys over the course of one year. In total, 245 anglers were interviewed on 68 survey days. On average, anglers spent 1.7 h fishing per trip and caught 0.385 fish h –1. A large proportion of anglers (43.9%) targeted multiple species, whereas 36.5% targeted largemouth bass ( Micropterus salmoides ), 10.0% targeted panfish (i.e., sunfishes [ Lepomis spp.] and crappies [ Pomoxis spp.]), and 9.6% targeted catfish ( Ameiurus spp. and Ictalurus spp.). Most anglers (69.4%) were satisfied with their experience, and overall satisfaction was unrelated to catch rate. Pulsed-DC boat electrofishing was conducted on 25 dates, and 617 fish were sampled. Angler catch rate was unrelated to electrofishing catch rate, implying that anglers' catch rate was independent of fish density or availability. Our results demonstrate that even minimally managed urban fisheries can provide high angler satisfaction, with limited dedication of management resources. Relationships Among Catch, Angler Satisfaction, and Fish Assemblage Characteristics of an Urban Small Impoundment Fishery (PDF Download Available). Available from: https://www.researchgate.net/publication/316636550_Relationships_Among_Catch_Angler_Satisfaction_and_Fish_Assemblage_Characteristics_of_an_Urban_Small_Impoundment_Fishery [accessed Aug 11, 2017].

North Carolina↗
USGS1991

Estimating wintering Bald Eagle densities in the Mississippi Alluvial Valley

Surveys on the winter distribution of Bald Eagles have been concentrated in the northern USA (Hastings 1988, Mattson 1988), where Bald Eagles are most common. Few density estimates for wintering Bald Eagles exist. In the past, different survey techniques with little standardization have been used. Statistical analyses and error measurements of existing winter survey data usually are not possible. The National Wildlife Federation's "midwinter Bald Eagle survey," the largest operational winter survey, is not systematic. Observers concentrate on areas where large numbers of Bald Eagles winter. We collected Bald Eagle density and distribution data in the Mississippi alluvial valley (MAV) while conducting four regional aerial surveys for Mallards ( Anas platyrhynchos ) during the winters of 1988-89 and 1989-90. Our objectives were to determine if the relatively large sample size and experimental design used in our Mallard surveys would provide accurate population estimates and additional distribution data not provided by current Bald Eagle surveys

Arkansas, Illinois, Kentucky, Louisiana, Mississip↗