Nathan D Chelgren
Science and Products
Stream Segments Captures and Crossings Associated With 2012 Aquatic Organism Passage Study Siuslaw National Forest
Stream segments, aquatic organism captures, stream surveys, and road-stream crossings described by these metadata accompany a 2012 electrofishing study of the distribution and abundance of aquatic organisms conducted by the U.S. Geological Survey, and the U.S. Forest.
FLOwPER user guide—For collection of FLOw PERmanence field observations
The accurate mapping of streams and their streamflow conditions in terms of presence or absence of surface water is important to both understanding physical, chemical, and biological processes in streams and to managing land, water, and ecological resources. This document describes a field form, FLOwPER (FLOw PERmanence), available within a mobile...
Jaeger, Kristin L.; Burnett, Jonathan; Heaston, Emily D.; Wondzell, Steve M.; Chelgren, Nathan; Dunham, Jason B.; Johnson, Sherri; Brown, Mike
Application of multiple-population viability analysis to evaluate species recovery alternatives
Population viability analysis (PVA) is a powerful conservation tool, but one that remains unapproachable for many species. This is particularly true for species with multiple, broadly-distributed populations for which collecting suitable data can be challenging. A recently-developed method of multiple population viability analysis (MPVA),...
Neville, Helen M.; Leasure, Douglas R.; Dauwalter, Daniel C.; Dunham, Jason B.; Bjork, Robin; Fesenmyer, Kurt A.; Chelgren, Nathan; Peacock, Mary M.; Luce, Charles H; Isaak, Daniel J.; Carranza, Lee Ann; Sjoberg, Jon; Wenger, Seth J. Hierarchical multi-population viability analysis
Population viability analysis (PVA) uses concepts from theoretical ecology to provide a powerful tool for quantitative estimates of population dynamics and extinction risks. However, conventional statistical PVA requires long-term data from every population of interest, whereas many species of concern exist in multiple isolated populations that...
Leasure, Douglas R.; Wenger, Seth J.; Chelgren, Nathan; Neville, Helen M.; Dauwalter, Daniel C.; Bjork, Robin; Fesenmyer, Kurt A.; Dunham, Jason B.; Peacock, Mary M.; Luce, Charlie H.; Lute, Abby C.; Isaak, Daniel J. Inference of timber harvest effects on survival of stream amphibians is complicated by movement
The effects of contemporary logging practices on headwater stream amphibians have received considerable study but with conflicting or ambiguous results. We posit that focusing inference on demographic rates of aquatic life stages may help refine understanding, as aquatic and terrestrial impacts may differ considerably. We investigated in-stream...
Chelgren, Nathan; Adams, M.J. Viability analysis for multiple populations
Many species of conservation interest exist solely or largely in isolated populations. Ideally, prioritization of management actions among such populations would be guided by quantitative estimates of extinction risk, but conventional methods of demographic population viability analysis (PVA) model each population separately and require temporally...
Wenger, Seth J.; Leasure, Douglas R.; Dauwalter, Daniel C.; Peacock, Mary M.; Dunham, Jason B.; Chelgren, Nathan; Neville, Helen M. Mercury and drought along the lower Carson River, Nevada: IV. Snowy egret post-fledging dispersal, timing of migration and survival, 2002–2004
This telemetry study is an extension of our 1997–2006 research on historical mercury contamination on snowy egrets (Egretta thula) up to ~ 20 days of age. Findings from initial studies at the mercury-contaminated Carson River colony at Lahontan Reservoir (LR) and a similar-sized reference (REF) colony on the Humboldt River included mercury-related...
Henny, Charles J.; Hill, Elwood F.; Grove, Robert A.; Chelgren, Nathan; Haggerty, Patricia K. Occupancy patterns of mammals and lentic amphibians in the Elwha River riparian zone before dam removal
The downstream transport of sediments and organics and upstream migration of anadromous fishes are key ecological processes in unregulated riverine ecosystems of the North Pacific coast, but their influence on wildlife habitats and populations is poorly documented. Removal of two large hydroelectric dams in Washington’s Elwha Valley provides...
Jenkins, Kurt J.; Chelgren, Nathan; Sager-Fradkin, K.A.; Happe, P.J.; Adams, M.J. Comparison of electrofishing techniques to detect larval lampreys in wadeable streams in the Pacific Northwest
We evaluated the probability of detecting larval lampreys using different methods of backpack electrofishing in wadeable streams in the U.S. Pacific Northwest. Our primary objective was to compare capture of lampreys using electrofishing with standard settings for salmon and trout to settings specifically adapted for capture of lampreys. Field...
Dunham, Jason B.; Chelgren, Nathan D.; Heck, Michael P.; Clark, Steven M. Using multilevel spatial models to understand salamander site occupancy patterns after wildfire
Studies of the distribution of elusive forest wildlife have suffered from the confounding of true presence with the uncertainty of detection. Occupancy modeling, which incorporates probabilities of species detection conditional on presence, is an emerging approach for reducing observation bias. However, the current likelihood modeling framework is...
Chelgren, Nathan; Adams, M.J.; Bailey, Larissa L.; Bury, R. Bruce Using spatiotemporal models and distance sampling to map the space use and abundance of newly metamorphosed Western Toads (Anaxyrus boreas)
High variability in abundance, cryptic coloration, and small body size of newly metamorphosed anurans have limited demographic studies of this life-history stage. We used line-transect distance sampling and Bayesian methods to estimate the abundance and spatial distribution of newly metamorphosed Western Toads (Anaxyrus boreas) in terrestrial...
Chelgren, Nathan D.; Samora, Barbara; Adams, M.J.; McCreary, Brome Using occupancy models to understand the distribution of an amphibian pathogen, Batrachochytrium dendrobatidis
Batrachochytrium dendrobatidis is a fungal pathogen that is receiving attention around the world for its role in amphibian declines. Study of its occurrence patterns is hampered by false negatives: the failure to detect the pathogen when it is present. Occupancy models are a useful but currently underutilized tool for analyzing detection data...
Adams, M.J.; Chelgren, Nathan; Reinitz, David M.; Cole, Rebecca A.; Rachowicz, L.J.; Galvan, Stephanie; McCreary, Brome; Pearl, Christopher A.; Bailey, Larissa L.; Bettaso, Jamie B.; Bull, Evelyn L.; Leu, Matthias Widespread occurrence of the chytrid fungus batrachochytrium dendrobatidis on oregon spotted frogs (rana pretiosa)
The pathogen Batrachochytrium dendrobatidis (Bd) has been associated with amphibian declines in multiple continents, including western North America. We investigated Bd prevalence in Oregon spotted frog (Rana pretiosa), a species that has declined across its range in the Pacific Northwest. Polymerase chain reaction analysis of skin swabs indicated...
Pearl, C.A.; Bowerman, J.; Adams, M.J.; Chelgren, N.D.
FLOwPER User’s Guide—For Collection of FLOw PERmanence Field Observations
USGS and USFS develop a mobile application field form for rapid collection of flow/no flow observations.
Application of Multiple-Population Viability Analysis to Evaluate Species Recovery Alternatives
A recently developed method of multiple population viability analysis (MPVA) addresses many limitations of traditional PVA.
Estimating Extinction Risk for Multiple Populations When Data for Traditional Population Viability Analyses are Unavailable
Population viability analysis (PVA) bridges the gap between theoretical and applied ecology and is used to make policy decisions on high-profile conservation efforts. However, it’s use is limited to a single or few populations with long-term data.