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Articles 1 - 30 of 42
Full-Text Articles in Physical Sciences and Mathematics
High Dispersal In A Frog Species Suggests That It Is Vulnerable To Habitat Fragmentation, W. Chris Funk, Allison E. Greene, Paul Stephen Corn, Fred W. Allendorf
High Dispersal In A Frog Species Suggests That It Is Vulnerable To Habitat Fragmentation, W. Chris Funk, Allison E. Greene, Paul Stephen Corn, Fred W. Allendorf
United States Geological Survey: Staff Publications
Global losses of amphibian populations are a major conservation concern and their causes have generated substantial debate. Habitat fragmentation is considered one important cause of amphibian decline. However, if fragmentation is to be invoked as a mechanism of amphibian decline, it must first be established that dispersal is prevalent among contiguous amphibian populations using formal movement estimators. In contrast, if dispersal is naturally low in amphibians, fragmentation can be disregarded as a cause of amphibian declines and conservation efforts can be focused elsewhere. We examined dispersal rates in Columbia spotted frogs (Rana luteiventris) using capture–recapture analysis of over …
Enhanced Marine Productivity Off Western North America During Warm Climate Intervals Of The Past 52 K.Y., J.D. Ortiz, S.B. O’Connell, J. Delviscio, W. Dean, J.D. Carriquiry, T. Marchitto, Y. Zheng, A. Van Geen
Enhanced Marine Productivity Off Western North America During Warm Climate Intervals Of The Past 52 K.Y., J.D. Ortiz, S.B. O’Connell, J. Delviscio, W. Dean, J.D. Carriquiry, T. Marchitto, Y. Zheng, A. Van Geen
United States Geological Survey: Staff Publications
Studies of the Santa Barbara Basin off the coast of California have linked changes in its bottom-water oxygen content to millennial-scale climate changes as recorded by the oxygen isotope composition of Greenland ice. Through the use of detailed records from a sediment core collected off the Magdalena Margin of Baja California, Mexico, we demonstrate that this teleconnection predominantly arose from changes in marine productivity, rather than changes in ventilation of the North Pacific, as was originally proposed. One possible interpretation is that the modern balance of El Nino–La Nina conditions that favors a shallow nutricline and high productivity today and …
Federal Listing Of Prairie Grouse: Lessons From The Attwater’S Prairie Chicken, Michael Morrow, Terry A. Rossignol, Nova J. Silvy
Federal Listing Of Prairie Grouse: Lessons From The Attwater’S Prairie Chicken, Michael Morrow, Terry A. Rossignol, Nova J. Silvy
United States Geological Survey: Staff Publications
Considerable controversy has often surrounded proposals to confer official status (i.e., list) species under the authority of the Endangered Species Act (ESA) of 1973 as amended or its precursors. Recent proposals to list the lesser prairie-chicken (Tympanuchus pallidicinctus), the western sage grouse (Centrocercus urophasianus phaios), and the Gunnison sage grouse (C. minimus) were met with strong opposition by those concerned with prospects of an increased regulatory environment associated with such an action. The Attwater's prairie-chicken (T. cupido attwateri) was one of the first species listed under The Endangered Species Conservation Act of …
Holocene Loess Deposition And Soil Formation As Competing Processes, Matanuska Valley, Southern Alaska, Daniel R. Muhs, John P. Mcgeehin, Jossh Beann, Eric Fisher
Holocene Loess Deposition And Soil Formation As Competing Processes, Matanuska Valley, Southern Alaska, Daniel R. Muhs, John P. Mcgeehin, Jossh Beann, Eric Fisher
United States Geological Survey: Staff Publications
Although loess–paleosol sequences are among the most important records of Quaternary climate change and past dust deposition cycles, few modern examples of such sedimentation systems have been studied. Stratigraphic studies and 22 new accelerator mass spectrometry radiocarbon ages from the Matanuska Valley in southern Alaska show that loess deposition there began sometime after ~6500 14C yr B.P. and has continued to the present. The silts are produced through grinding by the Matanuska and Knik glaciers, deposited as outwash, entrained by strong winds, and redeposited as loess. Over a downwind distance of ~40 km, loess thickness, sand content, and sand-pluscoarse- …
Corrigendum To ‘‘Radiocarbon Dating, Chronologic Framework, And Changes In Accumulation Rates Of Holocene Estuarine Sediments From Chesapeake Bay’’ [Quaternary Research 57 (2002) 58–70], Steven M. Colman, Pattie C. Baucom, John F. Bratton, Thomas M. Cronin, John P. Mcgeehin, Debra Willard, Andrew R. Zimmerman, Peter R. Vogt
Corrigendum To ‘‘Radiocarbon Dating, Chronologic Framework, And Changes In Accumulation Rates Of Holocene Estuarine Sediments From Chesapeake Bay’’ [Quaternary Research 57 (2002) 58–70], Steven M. Colman, Pattie C. Baucom, John F. Bratton, Thomas M. Cronin, John P. Mcgeehin, Debra Willard, Andrew R. Zimmerman, Peter R. Vogt
United States Geological Survey: Staff Publications
Because of an error in the calculation of bulk densities from water contents, the cumulative masses in Fig. 8 are too high by a factor of about 2. The actual correction depends to small degree on water content and ranges from 1.8 for a water content of 50% to 2.2 for a water content of 75%. The values for mass accumulation rates in the left two columns of Table 5 are also affected, but the ratios between pre- and post-settlement times are not. A revised version of that table is given below. None of the major conclusions of the paper …
Limnological And Climatic Environments At Upper Klamath Lake, Oregon During The Past 45 000 Years, J. Platt Bradbury, Steven M. Colman, Walter E. Dean
Limnological And Climatic Environments At Upper Klamath Lake, Oregon During The Past 45 000 Years, J. Platt Bradbury, Steven M. Colman, Walter E. Dean
United States Geological Survey: Staff Publications
Upper Klamath Lake, in south-central Oregon, contains long sediment records with well-preserved diatoms and lithological variations that reflect climate-induced limnological changes. These sediment archives complement and extend high resolution terrestrial records along a north–south transect that includes areas influenced by the Aleutian Low and Subtropical High, which control both marine and continental climates in the western United States. The longest and oldest core collected in this study came from the southwest margin of the lake at Caledonia Marsh, and was dated by radiocarbon and tephrochronology to an age of about 45 ka. Paleolimnological interpretations of this core, based upon geochemical …
Fine-Scale Structure Of The San Andreas Fault Zone And Location Of The Safod Target Earthquakes, C. Thurber, S. Roecker, H. Zhang, S. Baher, W. Ellsworth
Fine-Scale Structure Of The San Andreas Fault Zone And Location Of The Safod Target Earthquakes, C. Thurber, S. Roecker, H. Zhang, S. Baher, W. Ellsworth
United States Geological Survey: Staff Publications
We present results from the tomographic analysis of seismic data from the Parkfield area using three different inversion codes. The models provide a consistent view of the complex velocity structure in the vicinity of the San Andreas, including a sharp velocity contrast across the fault. We use the inversion results to assess our confidence in the absolute location accuracy of a potential target earthquake. We derive two types of accuracy estimates, one based on a consideration of the location differences from the three inversion methods, and the other based on the absolute location accuracy of ‘‘virtual earthquakes.’’ Location differences are …
A Mechanical Model Of The San Andreas Fault And Safod Pilot Hole Stress Measurements, Jean Chéry, Mark D. Zoback, Stephen Hickman
A Mechanical Model Of The San Andreas Fault And Safod Pilot Hole Stress Measurements, Jean Chéry, Mark D. Zoback, Stephen Hickman
United States Geological Survey: Staff Publications
Stress measurements made in the SAFOD pilot hole provide an opportunity to study the relation between crustal stress outside the fault zone and the stress state within it using an integrated mechanical model of a transform fault loaded in transpression. The results of this modeling indicate that only a fault model in which the effective friction is very low (<0.1) through the seismogenic thickness of the crust is capable of matching stress measurements made in both the far field and in the SAFOD pilot hole. The stress rotation measured with depth in the SAFOD pilot hole (~28 ° ) appears to be a typical feature of a weak fault embedded in a strong crust and a weak upper mantle with laterally variable heat flow, although our best model predicts less rotation (15 ° ) than observed. Stress magnitudes predicted by our model within the fault zone indicate low shear stress on planes parallel to the fault but a very anomalous mean stress, approximately twice the lithostatic stress.
Uranium-Series Coral Ages From The Us Atlantic Coastal Plain–The ‘‘80 Ka Problem’’ Revisited, John F. Wehmiller, Kathleen R. Simmons, Hai Cheng, R. Lawrence Edwards, Jamie Martin-Mcnaughton, Linda L. York, David E. Krantz, Chuan-Chou Shen
Uranium-Series Coral Ages From The Us Atlantic Coastal Plain–The ‘‘80 Ka Problem’’ Revisited, John F. Wehmiller, Kathleen R. Simmons, Hai Cheng, R. Lawrence Edwards, Jamie Martin-Mcnaughton, Linda L. York, David E. Krantz, Chuan-Chou Shen
United States Geological Survey: Staff Publications
Uranium series coral ages for emergent units from the passive continental margin US Atlantic Coastal Plain (ACP) suggest sea level above present levels at the end of marine oxygen isotope stage (MIS) 5, contradicting age-elevation relations based on marine isotopic or coral reef models of ice equivalent sea level. We have reexamined this problem by obtaining high precision 230Th/238U and 231Pa/235U thermal ionization mass spectrometric ages for recently collected and carefully cleaned ACPcorals, many in situ. We recognize samples that show no evidence for diagenesis on the basis of uranium isotopic composition and age …
Persistence Of Pharmaceutical Compounds And Other Organic Wastewater Contaminants In A Conventional Drinking-Water-Treatment Plant, Paul E. Stackelberg, Edward T. Furlong, Michael T. Meyer, Steven D. Zaugg, Alden K. Henderson, Dori B. Reissman
Persistence Of Pharmaceutical Compounds And Other Organic Wastewater Contaminants In A Conventional Drinking-Water-Treatment Plant, Paul E. Stackelberg, Edward T. Furlong, Michael T. Meyer, Steven D. Zaugg, Alden K. Henderson, Dori B. Reissman
United States Geological Survey: Staff Publications
In a study conducted by the US Geological Survey and the Centers for Disease Control and Prevention, 24 water samples were collected at selected locations within a drinking-water-treatment (DWT) facility and from the two streams that serve the facility to evaluate the potential for wastewater-related organic contaminants to survive a conventional treatment process and persist in potable-water supplies. Stream-water samples as well as samples of raw, settled, filtered, and finished water were collected during low-flow conditions, when the discharge of effluent from upstream municipal sewage-treatment plants accounted for 37–67% of flow in stream 1 and 10–20% of flow in stream …
Estimating Accumulation Rates And Physical Properties Of Sediment Behind A Dam: Englebright Lake, Yuba River, Northern California, Noah P. Snyder, David M. Rubin, Charles N. Alpers, Jonathan R. Childs, Jennifer A. Curtis, Lorraine E. Flint, Scott A. Wright
Estimating Accumulation Rates And Physical Properties Of Sediment Behind A Dam: Englebright Lake, Yuba River, Northern California, Noah P. Snyder, David M. Rubin, Charles N. Alpers, Jonathan R. Childs, Jennifer A. Curtis, Lorraine E. Flint, Scott A. Wright
United States Geological Survey: Staff Publications
Studies of reservoir sedimentation are vital to understanding scientific and management issues related to watershed sediment budgets, depositional processes, reservoir operations, and dam decommissioning. Here we quantify the mass, organic content, and grain-size distribution of a reservoir deposit in northern California by two methods of extrapolating measurements of sediment physical properties from cores to the entire volume of impounded material. Englebright Dam, completed in 1940, is located on the Yuba River in the Sierra Nevada foothills. A research program is underway to assess the feasibility of introducing wild anadromous fish species to the river upstream of the dam. Possible management …
Grassland Vegetation And Bird Communities In The Southern Great Plains Of North America, Robert N. Chapman, David M. Engle, Ronald E. Masters, David M. Leslie Jr.
Grassland Vegetation And Bird Communities In The Southern Great Plains Of North America, Robert N. Chapman, David M. Engle, Ronald E. Masters, David M. Leslie Jr.
United States Geological Survey: Staff Publications
Structure and composition of vegetation and abundance of breeding birds in grasslands seeded to Old World bluestem (Bothriochloa ischmaeum) were compared to native mixed prairie in the southern Great Plains of North America. Abundance of birds was determined using fixed-radius point counts. Detrended correspondence analysis was used to compare plant community composition and canonical correspondence analysis was used to examine the relationships between plant species composition and vegetation structure with the bird community. Plant species composition differed distinctly between seeded grassland and native mixed prairie, but the differences were not reflected in habitat structure, bird community composition, or …
Record Of Late Pleistocene Glaciation And Deglaciation In The Southern Cascade Range. I. Petrological Evidence From Lacustrine Sediment In Upper Klamath Lake, Southern Oregon, Richard L. Reynolds, Joseph G. Rosenbaum, Josh Rapp, Michael W. Kerwin, J. Platt Bradbury, David Adam, Steven Colman
Record Of Late Pleistocene Glaciation And Deglaciation In The Southern Cascade Range. I. Petrological Evidence From Lacustrine Sediment In Upper Klamath Lake, Southern Oregon, Richard L. Reynolds, Joseph G. Rosenbaum, Josh Rapp, Michael W. Kerwin, J. Platt Bradbury, David Adam, Steven Colman
United States Geological Survey: Staff Publications
Petrological and textural properties of lacustrine sediments from Upper Klamath Lake, Oregon, reflect changing input volumes of glacial flour and thus reveal a detailed glacial history for the southern Cascade Range between about 37 and 15 ka. Magnetic properties vary as a result of mixing different amounts of the highly magnetic, glacially generated detritus with less magnetic, more weathered detritus derived from unglaciated parts of the large catchment. Evidence that the magnetic properties record glacial flour input is based mainly on the strong correlation between bulk sediment particle size and parameters that measure the magnetite content and magnetic mineral freshness. …
Paleolimnology And Paleoclimate Studies In Upper Klamath Lake, Oregon, Steven M. Colman, J. Platt Bradbury, Joseph G. Rosenbaum
Paleolimnology And Paleoclimate Studies In Upper Klamath Lake, Oregon, Steven M. Colman, J. Platt Bradbury, Joseph G. Rosenbaum
United States Geological Survey: Staff Publications
The subsiding Upper Klamath Lake Basin contains sediments that were continuously deposited in a shallow, freshwater lake for more than 40 000 years. Well dated by radiometric methods and containing volcanic ashes of known age, these sediments constitute a valuable paleoclimate record. Sediment constituents and properties that reflect past climatic conditions in the area include pollen, diatoms, sediment geochemistry, and sediment magnetic properties. Many of these proxy measurements are also useful for comparing natural conditions in the lake to conditions following human settlement. Because of its location, the paleoclimate record from Upper Klamath Lake is valuable for comparisons to offshore …
Chronology Of Sediment Deposition In Upper Klamath Lake, Oregon, Steven M. Colman, J. Platt Bradbury, John P. Mcgeehin, Charles W. Holmes, David Edginton, Andrei M. Sarna-Wojcicki
Chronology Of Sediment Deposition In Upper Klamath Lake, Oregon, Steven M. Colman, J. Platt Bradbury, John P. Mcgeehin, Charles W. Holmes, David Edginton, Andrei M. Sarna-Wojcicki
United States Geological Survey: Staff Publications
A combination of tephrochronology and 14C, 210Pb, and 137Cs measurements provides a robust chronology for sedimentation in Upper Klamath Lake during the last 45 000 years. Mixing of surficial sediments and possible mobility of the radio-isotopes limit the usefulness of the 137Cs and 210Pb data, but 210Pb profiles provide reasonable average sediment accumulation rates for the last 100–150 years. Radiocarbon ages near the top of the core are somewhat erratic and are too old, probably as a result of detrital organic carbon, which may have become a more common component in recent times as …
Mortality Of An Adult Cougar Due To A Forest Fire, Dorothy M. Fecske, Jonathan A. Jenks, Frederick D. Lindzey
Mortality Of An Adult Cougar Due To A Forest Fire, Dorothy M. Fecske, Jonathan A. Jenks, Frederick D. Lindzey
United States Geological Survey: Staff Publications
Mortality from natural causes has been documented throughout the range of the cougar (Puma concolor), including California (Beier and Barrett 1993), Canada (Ross et al. 1995), Florida (Taylor et al. 2002), Idaho (Hornocker 1970), Nevada (Ashman et al. 1983), New Mexico (Logan and Sweanor 2001), and Utah (Gashwiler and Robinette 1957, Lindzey et al. 1988). Intraspecific killing by adult males is the most common cause of death in unhunted populations; adult males have killed kittens, subadults, and adults of both sexes (Beier and Barrett 1993, Maehr 1997, Logan and Sweanor 2001, Taylor et al. 2002). Other mortality factors …
Great Plains Ecosystems: Past, Present, And Future, Fred B. Samson, Fritz L. Knopf, Wayne Ostlie
Great Plains Ecosystems: Past, Present, And Future, Fred B. Samson, Fritz L. Knopf, Wayne Ostlie
United States Geological Survey: Staff Publications
Little questions exists that the main bodies of North American prairie (i.e., the tall-grass, mixed, and shortgrass) are among the most endangered resources on the continent. The purpose of this paper is to provide a past and present biological base- line by which to understand North American prairies and to provide a platform for future conservation. Events both immediate to the end of the Pleistocene and historic suggest that the present grassland conditions are different from those within which most of the grassland organisms evolved. Our analysis suggests that few grassland landscapes remain adequate in area and distribution to sustain …
Genetic Structure Of Cougar Populations Across The Wyoming Basin: Metapopulation Or Megapopulation, Charles R. Anderson Jr., Federick G. Lindzey, David B. Mcdonald
Genetic Structure Of Cougar Populations Across The Wyoming Basin: Metapopulation Or Megapopulation, Charles R. Anderson Jr., Federick G. Lindzey, David B. Mcdonald
United States Geological Survey: Staff Publications
We examined the genetic structure of 5 Wyoming cougar (Puma concolor) populations surrounding the Wyoming Basin, as well as a population from southwestern Colorado. When using 9 microsatellite DNA loci, observed heterozygosity was similar among populations (HO = 0.49–0.59) and intermediate to that of other large carnivores. Estimates of genetic structure (FST = 0.028, RST = 0.029) and number of migrants per generation (Nm) suggested high gene flow. Nm was lowest between distant populations and highest among adjacent populations. Examination of these data, plus Mantel test results of genetic versus geographic distance (P ≤ 0.01), suggested both isolation …
History Of Greater Sage-Grouse In The Dakotas: Distribution And Population Trends, Joe T. Smith, Lester D. Flake, Kenneth F. Higgins, Gerald D. Kobriger
History Of Greater Sage-Grouse In The Dakotas: Distribution And Population Trends, Joe T. Smith, Lester D. Flake, Kenneth F. Higgins, Gerald D. Kobriger
United States Geological Survey: Staff Publications
The greater sage-grouse (Centrocercus urophasianus) has declined throughout its range and its status is of major concern to federal, state, and provincial wildlife agencies. We collected information on current and historical greater sage-grouse distribution and lek activity in western North and South Dakota. A steady decline in lek attendance by males occurred over the entire recorded period in North Dakota (1951-2002) and South Dakota (1972-2002). There was no apparent change in numbers of known active leks due to discovery of new leks, but there was an abandonment of regions once occupied by active leks.
Mineralogical Maturity In Dunefields Of North America, Africa And Australia, Daniel R. Muhs
Mineralogical Maturity In Dunefields Of North America, Africa And Australia, Daniel R. Muhs
United States Geological Survey: Staff Publications
Studies of dunefields in central and western North America show that mineralogical maturity can provide new insights into the origin and evolution of aeolian sand bodies. Many of the world’s great sand seas in Africa, Asia and Australia are quartz-dominated and thus can be considered to be mineralogically mature. The Algodones (California) and Parker (Arizona) dunes in the southwestern United States are also mature, but have inherited a high degree of mineralogical maturity from quartz-rich sedimentary rocks drained by the Colorado River. In Libya, sediments of the Zallaf sand sea, which are almost pure quartz, may have originated in a …
Testing Density-Dependent Groundwater Models: Two-Dimensional Steady State Unstable Convection In Infinite, Finite And Inclined Porous Layers, Douglas Weatherill, Craig T. Simmons, Clifford I. Voss, Neville I. Robinson
Testing Density-Dependent Groundwater Models: Two-Dimensional Steady State Unstable Convection In Infinite, Finite And Inclined Porous Layers, Douglas Weatherill, Craig T. Simmons, Clifford I. Voss, Neville I. Robinson
United States Geological Survey: Staff Publications
This study proposes the use of several problems of unstable steady state convection with variable fluid density in a porous layer of infinite horizontal extent as two-dimensional (2-D) test cases for density-dependent groundwater flow and solute transport simulators. Unlike existing density-dependent model benchmarks, these problems have well-defined stability criteria that are determined analytically. These analytical stability indicators can be compared with numerical model results to test the ability of a code to accurately simulate buoyancy driven flow and diffusion. The basic analytical solution is for a horizontally infinite fluid-filled porous layer in which fluid density decreases with depth. The proposed …
Introduction To Special Section: Preparing For The San Andreas Fault Observatory At Depth, Stephen Hickman, Mark D. Zoback, William Ellsworth
Introduction To Special Section: Preparing For The San Andreas Fault Observatory At Depth, Stephen Hickman, Mark D. Zoback, William Ellsworth
United States Geological Survey: Staff Publications
The San Andreas Fault Observatory at Depth (SAFOD) is a comprehensive project to drill into the hypocentral zone of repeating M ~ 2 earthquakes on the San Andreas Fault at a depth of about 3 km. The goals of SAFOD are to establish a multi-stage geophysical observatory in close proximity to these repeating earthquakes, to carry out a comprehensive suite of downhole measurements in order to study the physical and chemical conditions under which earthquakes occur and to exhume rock and fluid samples for extensive laboratory studies. In the vicinity of SAFOD, the San Andreas is moving through a combination …
Stress-Induced, Time-Dependent Fracture Closure At Hydrothermal Conditions, N. M. Beeler, S. H. Hickman
Stress-Induced, Time-Dependent Fracture Closure At Hydrothermal Conditions, N. M. Beeler, S. H. Hickman
United States Geological Survey: Staff Publications
Time-dependent closure of fractures in quartz was measured in situ at 22–530 °C temperature and 0.1–150 MPa water pressure. Unlike previous crack healing and rock permeability studies, in this study, fracture aperture is monitored directly and continuously using a windowed pressure vessel, a long-working-distance microscope, and reflectedlight interferometry. Thus the fracture volume and geometry can be measured as a function of time, temperature, and water pressure. Relatively uniform closure occurs rapidly at temperatures and pressures where quartz becomes significantly soluble in water. During closure the aperture is reduced by as much as 80% in a few hours. We infer that …
Genetic Identification Of Spotted Owls, Barred Owls, And Their Hybrids: Legal Implications Of Hybrid Identity, Susan M. Haig, Thomas D. Mullins, Eric D. Forsman, Pepper W. Trail, Liv Wennerberg
Genetic Identification Of Spotted Owls, Barred Owls, And Their Hybrids: Legal Implications Of Hybrid Identity, Susan M. Haig, Thomas D. Mullins, Eric D. Forsman, Pepper W. Trail, Liv Wennerberg
United States Geological Survey: Staff Publications
Recent population expansion of Barred Owls (Strix varia) into western North America has led to concern that they may compete with and further harm the Northern Spotted Owl (S. occidentalis caurina), which is already listed as threatened under the U.S. Endangered Species Act (ESA). Because they hybridize, there is a legal need under the ESA for forensic identification of both species and their hybrids. We used mitochondrial control-region DNA and amplified fragment-length polymorphism (AFLP) analyses to assess maternal and biparental gene flow in this hybridization process. Mitochondrial DNA sequences (524 base pairs) indicated large divergence between …
Subspecific Relationships And Genetic Structure In The Spotted Owl, Susan M. Haig, Thomas D. Mullins, Eric D. Forsman
Subspecific Relationships And Genetic Structure In The Spotted Owl, Susan M. Haig, Thomas D. Mullins, Eric D. Forsman
United States Geological Survey: Staff Publications
Hierarchical genetic structure was examined in the three geographically-defined subspecies of spotted owl (Strix occidentalis) to define relationships among subspecies and quantify variation within and among regional and local populations. Sequences (522 bp) from domains I and II of the mitochondrial control region were analyzed for 213 individuals from 30 local breeding areas. Results confirmed significant differences between northern spotted owls and the other traditional geographically defined subspecies but did not provide support for subspecific level differences between California and Mexican spotted owls. Divergence times among subspecies estimated with a 936 bp portion of the cytochrome b gene …
Mudfish On The Menu? Rise Of The Much-Maligned Bowfin, Ken Sulak
Mudfish On The Menu? Rise Of The Much-Maligned Bowfin, Ken Sulak
United States Geological Survey: Staff Publications
Cajuns call it “choupique” (say “shoe-pick”), from its Choctaw name. Elsewhere, it’s the dogfish, blackfish, grindle, cottonfish, or cypress trout. Its official common name is “Bowfin” (Amia calva)1. But to most anglers, this is the “mudfish,” a strange, unusual, and much-maligned fish, most everywhere considered a useless trash fish. One look and the words relict, prehistoric, primitive, and living fossil come to mind. Indeed, the bowfin is the last of its line, the sole-surviving species of a very ancient group of fishes. Its predecessors flourished in the Jurassic and Cretaceous periods during the Mesozoic (= Middle-Animal) Era, a …
Stable Hydrogen Isotope Analysis Of Bat Hair As Evidence For Seasonal Molt And Long-Distance Migration, Paul M. Cryan, Michael A. Bogan, Robert O. Rye, Gary P. Landis, Cynthia L. Kester
Stable Hydrogen Isotope Analysis Of Bat Hair As Evidence For Seasonal Molt And Long-Distance Migration, Paul M. Cryan, Michael A. Bogan, Robert O. Rye, Gary P. Landis, Cynthia L. Kester
United States Geological Survey: Staff Publications
Although hoary bats (Lasiurus cinereus) are presumed to be migratory and capable of long-distance dispersal, traditional marking techniques have failed to provide direct evidence of migratory movements by individuals. We measured the stable hydrogen isotope ratios of bat hair (∂Dh) and determined how these values relate to stable hydrogen isotope ratios of precipitation (∂Dp). Our results indicate that the major assumptions of stable isotope migration studies hold true for hoary bats and that the methodology provides a viable means of determining their migratory movements. We present evidence that a single annual molt occurs in L. cinereus …
New Distributional Record Of The Nothern Redbelly Dace In The Northern Great Plains, Nathan M. Morey, Charles R. Berry Jr.
New Distributional Record Of The Nothern Redbelly Dace In The Northern Great Plains, Nathan M. Morey, Charles R. Berry Jr.
United States Geological Survey: Staff Publications
The range of the northern redbelly dace (Phoxinus eos) is grouped into two regions in central North America (Stasiak 1980). In the northern Great Plains, the species is distributed throughout the upper Missouri River drainage in Montana and Canada (Brown 1971, Scott and Crossman 1973). In the Central Lowlands, the northern redbelly dace is distributed through northern Minnesota, Wisconsin, Canada, and the Great Lakes region (Hubbs and Cooper 1936, Eddy and Underhill 1976, Becker 1983). The present distribution of northern redbelly dace has shifted northward from a more southerly distribution during Pleistocene glaciation (Cross et al. 1986). Relict …
Sources Of Ancient Maize Found In Chacoan Great Houses, Larry Benson
Sources Of Ancient Maize Found In Chacoan Great Houses, Larry Benson
United States Geological Survey: Staff Publications
Between the 9th and 12th centuries A.D., Chaco Canyon, located near the middle of the high-desert San Juan Basin of north-central New Mexico (fig. 1), was the focus of an unprecedented construction effort by pre-Columbian Native Americans. It has been estimated that from 2,000 to 6,000 people occupied Chaco Canyon during its heyday (Windes, 1984; Drager, 1976). One indication of Chaco’s regional importance is a network of roads that linked Chaco Canyon with other great houses and communities spread throughout a region covering at least 60,000 km2 (fig. 2). At the height of its cultural florescence in the 11th century, …
A Holocene Pollen Record Of Persistent Droughts From Pyramid Lake, Nevada, Usa, Scott A. Mensing, Larry Benson, Michaele Kashgarian, Steve Lund
A Holocene Pollen Record Of Persistent Droughts From Pyramid Lake, Nevada, Usa, Scott A. Mensing, Larry Benson, Michaele Kashgarian, Steve Lund
United States Geological Survey: Staff Publications
Pollen and algae microfossils preserved in sediments from Pyramid Lake, Nevada, provide evidence for periods of persistent drought during the Holocene age. We analyzed one hundred nineteen 1-cm-thick samples for pollen and algae from a set of cores that span the past 7630 years. The early middle Holocene, 7600 to 6300 cal yr B.P., was found to be the driest period, although it included one short but intense wet phase. We suggest that Lake Tahoe was below its rim for most of this period, greatly reducing the volume and depth of Pyramid Lake. Middle Holocene aridity eased between 5000 and …