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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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Fatty acid profiles of feeding and fasting bears: Estimating calibration coefficients, the timeframe of diet estimates, and selective mobilization during hibernation Fatty acid profiles of feeding and fasting bears: Estimating calibration coefficients, the timeframe of diet estimates, and selective mobilization during hibernation

Accurate information on diet composition is central to understanding and conserving carnivore populations. Quantitative fatty acid signature analysis (QFASA) has emerged as a powerful tool for estimating the diets of predators, but ambiguities remain about the timeframe of QFASA estimates and the need to account for species-specific patterns of metabolism. We conducted a series of...
Authors
Gregory W. Thiemann, Karyn D. Rode, Joy A Erlenbach, Suzanne Budge, Charles T. Robbins

Offspring of translocated individuals drive the successful reintroduction of Columbian Sharp-tailed Grouse in Nevada, USA Offspring of translocated individuals drive the successful reintroduction of Columbian Sharp-tailed Grouse in Nevada, USA

Translocations of North American prairie-grouse (genus Tympanuchus) present a conservation paradox wherein they are performed to augment, restore, or reintroduce populations, but translocated individuals exhibit a diminished ability to contribute to population restoration. For reintroduced populations without immigration, persistence can only be achieved through reproductive...
Authors
Steven R. Mathews, Peter S. Coates, Brian G. Prochazka, Shawn P. Espinosa, David J. Delehanty

Pb-Pb and U-Pb dating of cassiterite by in situ LA-ICPMS: Examples spanning ~1.85 Ga to ~100 Ma in Russia and implications for dating Proterozoic to Phanerozoic tin deposits. Pb-Pb and U-Pb dating of cassiterite by in situ LA-ICPMS: Examples spanning ~1.85 Ga to ~100 Ma in Russia and implications for dating Proterozoic to Phanerozoic tin deposits.

This paper investigates applicability of cassiterite to dating ore deposits in a wide age range. We report in situ LA-ICPMS U-Pb and Pb-Pb dating results (n = 15) of cassiterite from six ore deposits in Russia ranging in age from ~1.85 Ga to 93 Ma. The two oldest deposits dated at ~1.83–1.86 Ga are rare metal Vishnyakovskoe located in the East Sayan pegmatite belt and tin deposits within...
Authors
Leonid A. Neymark, Anatoly M. Larin, Richard J. Moscati

Biodiversity–productivity relationships in a natural grassland community vary under diversity loss scenarios Biodiversity–productivity relationships in a natural grassland community vary under diversity loss scenarios

Understanding the biodiversity–productivity relationship and underlying mechanisms in natural ecosystems under realistic diversity loss scenarios remains a major challenge for ecologists despite its importance for predicting impacts of rapid loss of biodiversity worldwide. Here we report the results of a plant functional group (PFG) removal experiment conducted on the Mongolian Plateau...
Authors
Qingmin Pan, Amy Symstad, Yongfei Bai, Jianhui Huang, Jianguo Wu, Shahid Naeem, Dima Chen, Dashuan Tian, Qibing Wang, Xingguo Han

Novel insights into the genetic population connectivity of transient whale sharks (Rhincodon typus) in Pacific Panama provide crucial data for conservation efforts Novel insights into the genetic population connectivity of transient whale sharks (Rhincodon typus) in Pacific Panama provide crucial data for conservation efforts

The whale shark (Rhincodon typus) is an endangered and highly migratory species, of which solitary individuals or aggregations are observed in oceans worldwide and for which conservation efforts are hindered by a lack of comprehensive data on genetic population connectivity. Tissue samples were collected from wandering whale sharks in Pacific Panama to determine genetic diversity...
Authors
Hector M. Guzman, Caitlin Beaver, Edgardo Diaz-Ferguson

Genetic diversity and structure in Arizona pronghorn following conservation efforts Genetic diversity and structure in Arizona pronghorn following conservation efforts

Arizona pronghorn (Antilocapra americana) population numbers have declined over the last century due to unregulated-harvest, population fragmentation, urban expansion, and habitat loss. Captive breeding, reintroductions, and translocations have helped to curb decline and boost population numbers of the endangered Sonoran subspecies (A. a. sonoriensis). To assess the effect of on-going...
Authors
Erin E. Vaughn, Melanie Culver

Recruitment bottlenecks for age-0 walleye in northern Wisconsin lakes Recruitment bottlenecks for age-0 walleye in northern Wisconsin lakes

Some northern Wisconsin lakes have shown declines in catches of age-0 Walleye Sander vitreus in standardized fall electrofishing sampling, suggesting that recruitment bottlenecks are occurring in the first several months of life. In 2016 and 2017, we sampled six lakes with declining trends in natural Walleye recruitment (D-NR lakes) and seven lakes with a history of sustained natural...
Authors
Jason Gostiaux, Hadley I. A. Boehm, Nathan J. Jaksha, Daniel J. Dembkowski, Joseph M. Hennessy, Daniel A. Isermann

Activity-based, genome-resolved metagenomics uncovers key populations and pathways involved in subsurface conversions of coal to methane Activity-based, genome-resolved metagenomics uncovers key populations and pathways involved in subsurface conversions of coal to methane

Microbial metabolisms and interactions that facilitate subsurface conversions of recalcitrant carbon to methane are poorly understood. We deployed an in situ enrichment device in a subsurface coal seam in the Powder River Basin (PRB), USA, and used BONCAT-FACS-Metagenomics to identify translationally active populations involved in methane generation from a variety of coal-derived...
Authors
Luke J. McKay, Heidi J. Smith, Elliott P. Barnhart, Hannah S. Schweitzer, Rex R. Malmstrom, Danielle Goudeau, Matthew W. Fields

Sexual dimorphism in morphology and plumage of endangered Yuma Ridgway’s Rails: A model for documenting sex Sexual dimorphism in morphology and plumage of endangered Yuma Ridgway’s Rails: A model for documenting sex

Many applications in wildlife management require knowledge of the sex of individual animals. The Yuma Ridgway's rail Rallus obsoletus yumanensis is an endangered marsh bird with monomorphic plumage and secretive behaviors, thereby complicating sex determination in field studies. We collected morphometric measurements from 270 adult Yuma Ridgway's rails and quantified the plumage and...
Authors
Courtney J. Conway, E. J. Harrity, L. E. Michael

Diets and stable isotope signatures of native and nonnative Leucisid fishes advances our understanding of the Yellowstone Lake food web Diets and stable isotope signatures of native and nonnative Leucisid fishes advances our understanding of the Yellowstone Lake food web

(1) Many forage fishes, such as Leucisids (minnows) have depauperate studies on diet composition or stable isotope signatures, as these fishes are often only viewed as food for higher trophic levels. The need exists to understand and document the diet and stable isotope signatures of Leucisids (redside shiner, longnose dace, lake chub) in relation to the community ecology and food-web...
Authors
Hayley C. Glassic, Christopher S. Guy, Todd M. Koel

Influence of redox gradients on nitrate transport from the landscape to groundwater and streams Influence of redox gradients on nitrate transport from the landscape to groundwater and streams

Increases in nitrogen applications to the land surface since the 1950s have led to a cascade of negative environmental impacts, including degradation of drinking water supplies, nutrient enrichment of aquatic ecosystems and contributions to global climate change. In this study, groundwater, streambed porewater, and stream sampling were used to establish trends in nitrate concentrations...
Authors
Anthony J. Tesoriero, Laurel E. Stratton, Matthew P. Miller

Assessing specific-capacity data and short-term aquifer testing to estimate hydraulic properties in alluvial aquifers of the Rocky Mountains, Colorado, USA Assessing specific-capacity data and short-term aquifer testing to estimate hydraulic properties in alluvial aquifers of the Rocky Mountains, Colorado, USA

Study Region: Rocky Mountains, United States Study Focus: Groundwater-flow modeling requires estimates of hydraulic properties, namely hydraulic conductivity. Hydraulic conductivity values commonly vary over orders of magnitudes however and estimation may require extensive field campaigns applying slug or pumping tests. As an alternative, specific-capacity tests can be used to estimate...
Authors
Connor P. Newman, Zachary D. Kisfalusi, Michael J. Holmberg
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