Aaron Johnston studies extinction dynamics and microrefugia of the American pika as a Mendenhall Fellow with Erik Beever. He is also an Affiliate Assistant Professor in the School of Environmental and Forest Sciences at the University of Washington.
Research Interest
Aaron is broadly interested in wildlife research that advances ecological theories and management of natural resources. His previous studies have involved a wide range of taxa in terrestrial and aquatic systems for investigations on rare species, invasive species, interspecific competition, forest management, and grazing effects on wildlife. Aaron is especially excited about innovative approaches to wildlife research facilitated by new remote-sensing technologies that describe habitat features across landscapes at high spatiotemporal resolutions. His recent studies on tree squirrels, red tree voles, and pikas have explored novel applications of airborne LiDAR that improved habitat modeling and hypothesis testing for these species. His current study involves developing new models for microtopography, microclimate, phenology, and snowpack dynamics from land-, air-, and space-based sensors to advance understanding of pika distributions and responses to climate change.
Education and Certifications
Ph.D. 2013. Wildlife Science, University of Washington
M.S. 2006. Wildlife Science, Oregon State University
B.S. 2000. Wildlife Ecology, Texas A&M University
Science and Products
USGS research on the effects of renewable energy on wildlife
Developing short science syntheses for use in NEPA analyses and decisions in the Bureau of Land Management
Annotated Bibliography of Scientific Research on Greater Sage-Grouse
Alpine Wildlife and Snowpack Dynamics in the North Cascades
Extinction dynamics and microrefugia of the American pika as climate changes.
Seasonal movements of mule deer and pronghorn in Wyoming, 2014-2021
Pronghorn Migration and Resource Selection Near Wind Energy Facilities in Wyoming, 2010-2012 and 2018-2020
Fractional cover estimates of sweet clover derived from UAV, aerial, and Sentinel-2 imagery for central Montana and northwest South Dakota, 2019
Seasonal Resource Selection by Pronghorn near Wind Energy Facilities in Wyoming, 2010-2012 and 2018-2020
Remotely sensed elk locations on the National Elk Refuge, Wyoming, 2017-2019
Hoary Marmot Abundance in North Cascades National Park 2007-2008 and 2016-2017
Counts of American Pikas and Hoary Marmots in North Cascades National Park 2016-2017
Beyond presence mapping: Predicting fractional cover of non-native vegetation in Sentinel-2 imagery using an ensemble of MaxEnt models
Wind-energy development alters pronghorn migration at multiple scales
Eyes on the herd: Quantifying ungulate density from satellite, unmanned aerial systems, and GPScollar data
Foreword to the special Issue on ‘The rapidly expanding role of drones as a tool for wildlife research’
Variable effects of wind-energy development on seasonal habitat selection of pronghorn
U.S. Geological Survey science for the Wyoming Landscape Conservation Initiative—2018 annual report
Human activities and weather drive contact rates of wintering elk
Freezing in a warming climate: Marked declines of a subnivean hibernator after a snow drought
Annotated bibliography of scientific research on greater sage-grouse published from 2015 to 2019
Comparative performance and trend of remotely sensed phenology and productivity metrics across the Western United States
Ecological consequences of anomalies in atmospheric moisture and snowpack
U.S. Geological Survey science for the Wyoming Landscape Conservation Initiative—2017 annual report
Non-USGS Publications**
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
- Science
USGS research on the effects of renewable energy on wildlife
Renewable energy development, such as solar and wind energy, is growing in the United States and is expected to continue expanding for the foreseeable future. However, renewable energy infrastructure can be a risk to some wildlife including threatened and endangered species. Wildlife managers and energy developers need wildlife risks to be assessed and effective strategies to mitigate those risks...Developing short science syntheses for use in NEPA analyses and decisions in the Bureau of Land Management
Scientific information is fundamental to understanding how proposed actions on public lands may impact the environment. However, agencies often have limited time to compile and synthesize existing science. We are working with the Bureau of Land Management to develop a new type of science product—short science syntheses—for facilitating use of the best available science in public lands decisions.Annotated Bibliography of Scientific Research on Greater Sage-Grouse
The greater sage-grouse has been a focus of scientific investigation and management action for the past two decades. The sheer number of scientific publications can be a challenge for managers tasked with evaluating and determining the need for potential updates to existing planning documents.Alpine Wildlife and Snowpack Dynamics in the North Cascades
Mountain ecosystems are expected to change with continued reductions in annual snowpack that have been observed worldwide over the past half-century. Recent snow droughts in North America have been attributed to unusually warm temperatures that cause winter precipitation to fall as rain, rather than snow. Many species of alpine wildlife depend on snowpack for insulation from extreme cold and for...Extinction dynamics and microrefugia of the American pika as climate changes.
Accurate projections of climate change and associated impacts on wildlife are now essential to conservation planning, but predictive models of range shifts for many species are often coarse, ignore extinction dynamics, and overestimate suitable habitat. Recent studies suggest the American pika (Ochotona princeps) is vulnerable to increasing heat stress in the Great Basin yet appears more resilient... - Data
Seasonal movements of mule deer and pronghorn in Wyoming, 2014-2021
USGS scientists evaluated the utility of hidden Markov movement models to characterize seasonal movements of mule deer (Odecoileus hemionus) and pronghorn (Antilocapra americana) that were tracked with GPS collars in Wyoming, USA, during 2014-2021. Data include step lengths and turning angles for individual animals at daily time-steps throughout the tracking period. Models demonstrated distinct sePronghorn Migration and Resource Selection Near Wind Energy Facilities in Wyoming, 2010-2012 and 2018-2020
USGS scientists evaluated movement and resource selection during seasonal migrations by pronghorn (Antilocapra americana) that were tracked with GPS collars near wind-energy facilities in the Shirley Basin, Wyoming, USA, in 2010-2012 and 2018-2020. Data include values of environmental variables and proximity to wind turbines at used and available locations for analyses of pronghorn selection of roFractional cover estimates of sweet clover derived from UAV, aerial, and Sentinel-2 imagery for central Montana and northwest South Dakota, 2019
Yellow sweet clover (Melilotus officinalis; clover hereafter) is a biennial legume native to Eurasia that is now present in all 50 states. Clover can grow 2 m tall and achieve high densities across large areas in the Northern Great Plains when conditions are conducive, such as in 2019. Clover is highly efficient at fixing nitrogen in soils which reduces the abundance of native grasses, while simulSeasonal Resource Selection by Pronghorn near Wind Energy Facilities in Wyoming, 2010-2012 and 2018-2020
Wind energy represents an important alternative to oil and gas extraction to meet increasing energy demands, but it has the potential to disrupt wildlife populations. Because behavioral adjustments, such as altered habitat selection, are a primary way that long-lived species respond to novel disturbances, USGS scientists evaluated effects of wind energy development on pronghorn (Antilocapra americRemotely sensed elk locations on the National Elk Refuge, Wyoming, 2017-2019
Remotely sensed elk locations were derived from satellite and Unmanned Aerial Systems (UAS) imagery collected during the winter of 2018 and the winter and spring of 2019 at the National Elk Refuge in Jackson, Wyoming and compared to locations from Global Positioning System (GPS) collars from 2017 - 2019. This data release provides the source, date, time, latitude, and longitude of elk locations anHoary Marmot Abundance in North Cascades National Park 2007-2008 and 2016-2017
USGS and NPS biologists used distance sampling to estimate abundance of hoary marmots (Marmota caligata) in North Cascades National Park, Washington, USA during 2007-2008 and 2016-2017. Biologists resurveyed hoary marmots in 2016 and 2017 at 78 point-count stations across 19 sites surveyed by NPS in 2007-2008. Data include marmot detection distances and survey conditions used to estimate abundanceCounts of American Pikas and Hoary Marmots in North Cascades National Park 2016-2017
USGS scientists counted American pikas (Ochotona princeps) and hoary marmots (Marmota caligata) in North Cascades National Park, Washington, USA during 2016. Hoary marmots were resurveyed in 2017, primarily by the National Park Service. Pika and marmot counts were collected to assess effects of weather and snowpack dynamics on these species. Counts are measures of relative abundance that may be us - Publications
Filter Total Items: 15
Beyond presence mapping: Predicting fractional cover of non-native vegetation in Sentinel-2 imagery using an ensemble of MaxEnt models
Non-native species maps are important tools for understanding and managing biological invasions. We demonstrate a novel approach to extend presence modeling to map fractional cover (FC) of non-native yellow sweet clover Melilotus officinalis in the Northern Great Plains, USA. We used ensembles of MaxEnt models to map FC across landscapes from satellite imagery trained from regional aerial imageryAuthorsTodd M. Preston, Aaron Johnston, Kyle Gregory Ebenhoch, Robert H. DiehlWind-energy development alters pronghorn migration at multiple scales
Migration is a critical behavioral strategy necessary for population persistence and ecosystem functioning, but migration routes have been increasingly disrupted by anthropogenic activities, including energy development. Wind energy is the world's fastest growing source of electricity and represents an important alternative to hydrocarbon extraction, but its effects on migratory species beyond birAuthorsMegan Cochran Milligan, Aaron Johnston, Jeffery L. Beck, Kaitlyn L. Taylor, Embere Hall, Lee Knox, Teal Cufaude, Cody Wallace, Geneva W. Chong, Matthew KauffmanEyes on the herd: Quantifying ungulate density from satellite, unmanned aerial systems, and GPScollar data
Novel approaches to quantifying density and distributions could help biologists adaptively manage wildlife populations, particularly if methods are accurate, consistent, cost-effective, rapid, and sensitive to change. Such approaches may also improve research on interactions between density and processes of interest, such as disease transmission across multiple populations. We assess how satelliteAuthorsTabitha Graves, Michael Yarnall, Aaron Johnston, Todd M. Preston, Geneva W. Chong, Eric K Cole, William Michael Janousek, Paul C. CrossForeword to the special Issue on ‘The rapidly expanding role of drones as a tool for wildlife research’
Drones have emerged as a popular wildlife research tool, but their use for many species and environments remains untested and research is needed on validation of sampling approaches that are optimised for unpiloted aircraft. Here, we present a foreword to a special issue that features studies pushing the taxonomic and innovation boundaries of drone research and thus helps address these knowledge aAuthorsAaron J Wirsing, Aaron Johnston, Jeremy J. KiszkaVariable effects of wind-energy development on seasonal habitat selection of pronghorn
In the face of climate change, wind energy represents an important alternative to oil and gas extraction to meet increasing energy demands, but it has the potential to disrupt wildlife populations. Because behavioral adjustments, such as altered habitat selection, are a primary way that long-lived species respond to novel disturbances, we evaluated effects of wind energy development on pronghorn (AuthorsMegan Cochran Milligan, Aaron Johnston, Jeff L Beck, Kurt T. Smith, Kaitlyn L. Taylor, Embere Hall, Lee Knox, Teal Cufaude, Cody Wallace, Geneva W. Chong, Matthew KauffmanU.S. Geological Survey science for the Wyoming Landscape Conservation Initiative—2018 annual report
The Wyoming Landscape Conservation Initiative (WLCI) was established in 2007 as a collaborative interagency partnership to develop and implement science-based conservation actions. During the past 11 years, partners from U.S. Geological Survey (USGS), State and Federal land management agencies, universities, and the public have collaborated to implement a long-term (more than 10 years) science-basAuthorsPatrick J. Anderson, Cameron L. Aldridge, Jason S. Alexander, Timothy J. Assal, Steven Aulenbach, Zachary H. Bowen, Anna D. Chalfoun, Geneva W. Chong, Holly Copeland, David R. Edmunds, Steve Germaine, Tabitha Graves, Julie A. Heinrichs, Collin G. Homer, Christopher Huber, Aaron Johnston, Matthew J. Kauffman, Daniel J. Manier, Ryan R. McShane, Cheryl A. Eddy-Miller, Kirk A. Miller, Adrian P. Monroe, Michael S. O'Donnell, Anna Ortega, Annika W. Walters, Daniel J. Wieferich, Teal B. Wyckoff, Linda ZeigenfussHuman activities and weather drive contact rates of wintering elk
Wildlife aggregation patterns can influence disease transmission. However, limited research evaluates the influence of anthropogenic and natural factors on aggregation. Many managers would like to reduce wildlife contact rates, driven by aggregation, to limit disease transmission. We develop a novel analytical framework to quantify how management activities such as supplemental feeding and huntingAuthorsWilliam Michael Janousek, Tabitha Graves, Ethan Berman, Geneva W. Chong, Eric K Cole, Sarah Dewey, Aaron Johnston, Paul C. CrossFreezing in a warming climate: Marked declines of a subnivean hibernator after a snow drought
Recent snow droughts associated with unusually warm winters are predicted to increase in frequency and affect species dependent upon snowpack for winter survival. Changes in populations of some cold‐adapted species have been attributed to heat stress or indirect effects on habitat from unusually warm summers, but little is known about the importance of winter weather to population dynamics and howAuthorsAaron Johnston, Roger G Christophersen, Erik A. Beever, Jason I. RansomAnnotated bibliography of scientific research on greater sage-grouse published from 2015 to 2019
The greater sage-grouse (Centrocercus urophasianus; hereafter GRSG) has been a focus of scientific investigation and management action for the past two decades. The 2015 U.S. Fish and Wildlife Service listing determination of “not warranted” was in part due to a large-scale collaborative effort to develop strategies to conserve GRSG populations and their habitat and to reduce threats to both. NewAuthorsSarah K. Carter, Robert S. Arkle, Heidi L. Bencin, Benjamin R. Harms, Daniel J. Manier, Aaron N. Johnston, Susan L. Phillips, Steven E. Hanser, Zachary H. BowenComparative performance and trend of remotely sensed phenology and productivity metrics across the Western United States
Vegetation phenology and productivity play a crucial role in surface energy balance, plant and animal distribution, and animal movement and habitat use and can be measured with remote sensing metrics including start of season (SOS), peak instantaneous rate of green-up date (PIRGd), peak of season (POS), end of season (EOS), and integrated vegetation indices. However, for most metrics, we do not yeAuthorsTabitha Graves, Ethan Edward Berman, Nathaniel Mikle, Jerod Merkle, Aaron Johnston, Geneva W. ChongEcological consequences of anomalies in atmospheric moisture and snowpack
Although increased frequency of extreme‐weather events is one of the most secure predictions associated with contemporary climate change, effects of such events on distribution and abundance of climate‐sensitive species remain poorly understood. Montane ecosystems may be especially sensitive to extreme weather because of complex abiotic and biotic interactions that propagate from climate‐driven reAuthorsAaron Johnston, Jason E. Bruggeman, Roger Christophersen, Aidan Beers, Erik A. Beever, Jason I. RansomU.S. Geological Survey science for the Wyoming Landscape Conservation Initiative—2017 annual report
The Wyoming Landscape Conservation Initiative (WLCI) was established in 2008 to address the scientific and conservation questions associated with land use changes because of energy development and other factors in southwest Wyoming. Over the past decade, partners from U.S. Geological Survey (USGS), State and Federal land management agencies, universities, and the public have collaborated to implemAuthorsLinda Zeigenfuss, Ellen Aikens, Cameron L. Aldridge, Patrick J. Anderson, Timothy J. Assal, Zachary H. Bowen, Anna D. Chalfoun, Geneva W. Chong, Cheryl A. Eddy-Miller, Stephen S. Germaine, Tabitha Graves, Collin G. Homer, Christopher Huber, Aaron Johnston, Matthew J. Kauffman, Daniel J. Manier, Ryan R. McShane, Kirk A. Miller, Adrian P. Monroe, Anna Ortega, Annika W. Walters, Teal B. WyckoffNon-USGS Publications**
Vander Haegen, W. M., G. R. Orth, A. N. Johnston and M. J. Linders. 2018. Endemic diseases affect population dynamics of tree squirrels in contrasting landscapes. Journal of Wildlife Management 82:328–343.Johnston, A. N. and L. M. Moskal. 2017. High-resolution habitat modeling with airborne LiDAR for red tree voles. Journal of Wildlife Management 81:58–72.Johnston, A. N. and R. G. Anthony. 2014. Brush mouse (Peromyscus boylii) occurrences in southern Oregon. Northwestern Naturalist 95:54–56.Ramsey, F. L. and A. N. Johnston. 2009. Trap mortality in mark-recapture studies. Environmental and Ecological Statistics 16:427–438.Johnston, A. N. and R. G. Anthony. 2008. Small-mammal microhabitat associations and response to grazing in Oregon. Journal of Wildlife Management 72:1736–1746.
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
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