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Browse more than 65,000 articles authored by our scientists over the past 100+ year history of the USGS and refine search by topic, location, year, and advanced search.

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Blanchard's cricket frogs (Acris blanchardi) have re-expanded northward since mid-2000s: Landscape predictors of occupancy Blanchard's cricket frogs (Acris blanchardi) have re-expanded northward since mid-2000s: Landscape predictors of occupancy

Blanchard's Cricket Frogs (Acris blanchardi) declined along their northern range edge in the upper Midwest in the mid-to late 1900s. The causes of these declines remain poorly understood, as does the current status of this species and their habitat requirements. In 2024, we revisited more than 300 locations previously sampled between 2003 and 2008 along this range edge in Minnesota...
Authors
Ryan C. Burner, Mark Roth, Aubrey A. Schwonek, Jason Tendler, Walter Sadinski, Andrew F. Badje, Rori A. Paloski

Multi-temporal mapping and analyses of post-wildfire surface soil moisture modeled from Landsat Thermal-IR and Sentinel-1 SAR Multi-temporal mapping and analyses of post-wildfire surface soil moisture modeled from Landsat Thermal-IR and Sentinel-1 SAR

Wildfires alter surface soil moisture by consuming vegetation and exposing the soil to increased solar radiation, increased precipitation throughfall, and reduced infiltration from soil hydrophobicity. This can affect the water balance within the watershed and, in turn, influence post-fire nutrient cycling and ecosystem succession. Modeling surface soil moisture over large areas using...
Authors
Britt Windsor Smith, Miguel L. Villarreal, Christopher E. Soulard, Joshua W. von Nonn

Ecological Benthic Units (EBUs): A new characterization of the global seafloor for ocean spatial planning and management Ecological Benthic Units (EBUs): A new characterization of the global seafloor for ocean spatial planning and management

Effective management of deep-sea ecosystems and the high seas is hindered by the absence of a globally consistent framework for characterizing benthic habitats. Here we present the first global ecological classification of the seafloor, comprising 250 unique ecological benthic units (EBUs), distributed on the seafloor as nearly 700,000 EBU polygon occurrences, generated by intersecting a...
Authors
Peter Harris, Dawn Wright, Kevin Butler, Keith VanGraafeiland, Mark Costello, Kerry Howell, Gustav Kagesten, Vanessa Lucier, Miles Macmillan-Lawler, Roger Sayre

Integrating detrital magnetite geochemistry and (U-Th)/He chronometry as a sediment provenance tool in geologic and metallogenic terranes Integrating detrital magnetite geochemistry and (U-Th)/He chronometry as a sediment provenance tool in geologic and metallogenic terranes

Magnetite is ubiquitous in porphyry Cu systems and in sediment sourcing both barren and mineralized regions, with potential as an indicator mineral in concealed and coarsely-mapped terranes. We develop and test a workflow for integrated geochemistry and (U–Th)/He (He) dating for inferring detrital magnetite (DMt) provenance in these settings. The ca. 70 Ma Taurus porphyry Cu–Mo(–Au)...
Authors
Robert Gregory McDermott, Douglas C. Kreiner, James V. Jones, Sean P. Regan, James R. Metcalf, Rebecca M. Flowers

Velocity-independent dry friction on mica: A realization of ideal Amontons-Coulomb friction Velocity-independent dry friction on mica: A realization of ideal Amontons-Coulomb friction

The Amontons-Coulomb friction law assumes that the frictional force between materials is independent of sliding velocity. However, as Coulomb noted, this is a rough approximation, and a second-order dependence of friction on the logarithm of sliding velocity is incorporated in a commonly used ‘rate- and state-dependent’ friction representation. Here we conduct shear experiments on mica...
Authors
Hiroshi Sakuma, Diane E. Moore, David A. Lockner, Toshihiro Kogure

Fatal leptospirosis in southern sea otters from Central California: Pathologic findings and detection of Leptospira interrogans Fatal leptospirosis in southern sea otters from Central California: Pathologic findings and detection of Leptospira interrogans

Leptospira interrogans serovar Pomona infections cause periodic outbreaks in California sea lions (CSLs; Zalophus californianus) and sporadic deaths in phocids. However, the frequency of infection and associated health impacts remain uncharacterized in sympatric threatened southern sea otters (SSOs; Enhydra lutris nereis), which serve as important sentinels of coastal health. Given the...
Authors
Margaret E. Martinez, Pádraig J. Duignan, Katherine C. Prager, Cara L. Field, Mary E. Gomes, Rinosh Mani, Lilian P. Carswell, Tim Tinker, Joseph A. Tomoleoni, Michael J. Murray, Ri K. Chang, Lloyd-Smith O. James

Amazonian mass balance history of Martian ice reservoirs: Current knowledge and uncertainties Amazonian mass balance history of Martian ice reservoirs: Current knowledge and uncertainties

A major part of the history of the Amazonian period on Mars is the movement of water ice between near-surface reservoirs across the planet. This work assesses the ages and volumes of different parts of the Martian water ice inventory over the last ∼1 Gyr, to reconstruct the time history of ice reservoirs to the extent that it is currently known and determine whether they provide a mass...
Authors
Colin M. Dundas

Testing the efficacy of industrial mitigation measures for caribou in the Arctic Testing the efficacy of industrial mitigation measures for caribou in the Arctic

1. Mitigation measures are commonly employed to reduce the negative effects of industrial development on wildlife but are not often evaluated for their efficacy. For example, oil fields in the Arctic typically incorporate design features intended to increase permeability for migratory, barren-ground caribou (Rangifer tarandus), even though there is limited empirical evidence of the...
Authors
Heather E. Johnson, John P. Severson

Estimating basal area change by tree size with Sentinel-2 imagery following four fires in California, USA Estimating basal area change by tree size with Sentinel-2 imagery following four fires in California, USA

Background Failure to account for tree size when estimating burn severity may not accurately capture post-fire tree mortality and post-fire forest structure. Aims We explored whether basal area mortality by tree size class could be determined from remotely-sensed burn severity indices based solely on Sentinel-2 satellite imagery. Methods We used data collected in four large California...
Authors
Micah C. Wright, Phillip J. van Mantgem, Christopher Y.S. Wong, Derek J.N. Young, Saba J. Saberi, Andrew M. Latimer, Joseph A.E. Stewart, Adrian J. Das, Calvin A. Farris, Emma J. McClure, Lauren N. Youngblood, Hugh D. Safford, Kristen L. Shive

Thermal detectability of subsurface water ice on Mars: A comparative analysis for the Subsurface Water Ice Mapping (SWIM) Project Thermal detectability of subsurface water ice on Mars: A comparative analysis for the Subsurface Water Ice Mapping (SWIM) Project

We have developed a new global map of shallow ground ice distribution, SWIM23, based on Mars Global Surveyor Thermal Emission Spectrometer data and made systematic comparisons between this new map and two similar, previously developed data products. We have explored the origin of differences between the three ice maps by detailing technical and procedural differences in their development...
Authors
H. G. Sizemore, A. V. Pathare, Colin M. Dundas, N. E. Putzig, G. A. Morgan, M. R. Perry, M. T. Mellon, Z. M. Bain, S. W. Courville

Structural evolution of iron coordination in proteins across Earth’s oxygenation history Structural evolution of iron coordination in proteins across Earth’s oxygenation history

Protein metal-binding sites support essential biological functions shaped by protein fold, subunit interactions, and cofactor chemistry. Because these sites encode both biochemical function and environmental constraint, they offer a route to connect protein evolution with changes in Earth’s surface environment through time. Of particular interest is iron (Fe), the most widely used metal...
Authors
Benjamin I. Jelen, Beth A. Christensen, Elisha Kelly Moore

Detecting occurrence and timing of grizzly bear parturition based on anomalies in accelerometer data Detecting occurrence and timing of grizzly bear parturition based on anomalies in accelerometer data

Documenting natality of brown (grizzly) bears (Ursus arctos) is an important component of many population monitoring and research programs. Brown bears give birth during hibernation, so observation of litters is generally not feasible until females exit dens, and detection of litters can be compromised by poor observability. Using triaxial accelerometer activity data stored on...
Authors
Lori L. Roberts, Cecily M. Costello, Milan A. Vinks, Daniel D. Bjornlie, Matthew D. Cameron, Justin G. Clapp, Mark A. Haroldson, Grant V. Hilderbrand, Kyle Joly, Wayne F. Kasworm, Jeremy M. Nicholson, Thomas G. Radandt, Mathew S. Sorum, Justin E. Teisberg, Frank T. van Manen
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