Brian Halstead
Dr. Brian Halstead is a Research Wildlife Biologist with the Western Ecological Research Center.
He focuses on conservation of reptiles and amphibians, particularly applications of population ecology to species conservation. In particular, he combines field methods like capture-mark-recapture and radio telemetry with flexible Bayesian hierarchical models to learn about demographic parameters and the individual, biotic, and environmental variables that affect them. Central themes of his research include the influence of land use, climate, and biotic interactions on species distributions and demographic rates; the behavioral response of individuals to habitat change; and providing relevant information for wildlife conservation to resource managers and private landowners. Currently, Dr. Halstead's research focuses on the effects of water availability on the distribution, behavior, and demography of giant gartersnakes (Thamnophis gigas); the response of San Francisco gartersnakes (Thamnophis sirtalis tetrataenia) to grazing and management of aquatic invasive species; and the influence of abiotic and biotic variables on the distribution and demography of amphibian populations in northern California. Additional research projects include the distribution, growth, and demography of island night lizards (Xantusia riversiana) on San Nicolas Island and monitoring Townsend’s big-eared bat (Corynorhinus townsendii) maternal colonies at Point Reyes National Seashore.
RESEARCH INTERESTS
- Population Ecology
- Conservation Biology
- Herpetology
- Bayesian Statistics
Education and Certifications
B.S. in Biology, Carroll College (Waukesha, WI), 1999
Ph.D. in Biology, University of South Florida, 2008
Science and Products
Site and Survey Data for Dixie Valley Toads in Churchill County, Nevada, 2019
Site and Survey Data for Amphibian Surveys in Yosemite National Park, 2018
Code and Data to Fit an Integrated Population Model for the Foothill Yellow-legged Frog, Rana boylii, in Northern California
Dixie Valley Toad Radio Telemetry Data from Churchill County, Nevada, 2018-2019
Code and Data Files to Construct an Integral Projection Model for Giant Gartersnakes (Thamnophis gigas) in the Sacramento Valley, California, 1995-2017
Amphibian capture mark-recapture
Coastal California San Francisco Gartersnake Capture-Mark-Recapture Data (2008-2013)
Time to detection data for Point Reyes pond-breeding amphibians, 2017
Hydrological measurements of 300 US temporary wetlands from 2004-2014
Occurrence of Amphibians in Northern California Coastal Dune Drainages
California Red-Legged Frogs in Point Reyes Coastal Dune Drainages (2015)
Microhabitat and Vegetation Selection by Giant Gartersnakes Associated with a Restored Marsh in California
Estimating the survival of unobservable life stages for a declining frog with a complex life-history
Occurrence of a suite of stream-obligate amphibians in timberlands of Mendocino County, California, examined using environmental DNA
Hatchling emergence ecology of Ouachita map turtles (Graptemys ouachitensis) on the lower Wisconsin River, Wisconsin, USA
Dispersal of hatchling Ouachita map turtles (Graptemys ouachitensis) from natural nests on the lower Wisconsin River, Wisconsin, USA
Time-to-detection occupancy methods: Performance and utility for improving efficiency of surveys
Virome of bat guano from nine northern California roosts
Distribution of giant gartersnakes (Thamnophis gigas) in the Sacramento–San Joaquin Delta, California, 2018–2019
Giant Gartersnakes (Thamnophis gigas) exploit abundant non-native prey while maintaining their appetite for native anurans
Batrachochytrium salamandrivorans (Bsal) not detected in an intensive survey of wild North American amphibians
Intrinsic prey preference and selection of the giant gartersnake: A threatened predator in a nonnative prey-dominated community
Integrating multiple data sources and multi-scale land-cover data to model the distribution of a declining amphibian
Demographic factors affecting population growth in giant gartersnakes
Science and Products
- Science
- Data
Filter Total Items: 36
Site and Survey Data for Dixie Valley Toads in Churchill County, Nevada, 2019
These data include site- and survey-specific information for occupancy surveys of Dixie Valley Toads (Anaxyrus williamsi) collected in the Dixie Valley, Churchill County, Nevada, in May 2019. The data include both multiple surveys of the same sites and time-to-detection information to quantify detection probabilities and account for imperfect detection in assessments of Dixie Valley Toad occupancySite and Survey Data for Amphibian Surveys in Yosemite National Park, 2018
These data represent occupancy surveys conducted in long-term monitoring sites in Yosemite National Park in 2018 for three anurans, the Yosemite Toad (Anaxyrus canorus), the Sierran Treefrog (Pseudacris sierra), and the Sierra Nevada Yellow-legged Frog (Rana sierrae). The data include independent double-observer surveys and time-to-detection data to calculate detection probabilities and account foCode and Data to Fit an Integrated Population Model for the Foothill Yellow-legged Frog, Rana boylii, in Northern California
These data include egg mass counts and adult capture-mark-recapture histories for Foothill Yellow-legged frogs (Rana boylii) at two streams in northern California. Data were collected from the South Fork Eel River and its tributary, Fox Creek, from 1993-2019. Data from Hurdygurdy Creek were collected from 2002-2008. This code and data support the following publication: Rose, JP, Kupferberg, SJDixie Valley Toad Radio Telemetry Data from Churchill County, Nevada, 2018-2019
This U.S. Geological Survey data release includes tabular data collected to characterize the habitat and movement of Dixie Valley toads. Data were collected in Dixie Valley, Nevada, in autumn 2018 and spring 2019. These data support the following publication: Halstead, B.J., Kleeman, P.M., Rose, J.P. and Fouts, K.J., 2021. Water Temperature and Availability Shape the Spatial Ecology of a HoCode and Data Files to Construct an Integral Projection Model for Giant Gartersnakes (Thamnophis gigas) in the Sacramento Valley, California, 1995-2017
This dataset includes data on the growth, fecundity, and survival of Giant Gartersnakes (Thamnophis gigas) in the Sacramento Valley of California from 1995-2017. In addition, the dataset includes R code to replicate the Integral Projection Model construction and analysis presented in the paper "Demographic drivers of population growth in a threatened snake" by Rose et al. published in Journal of WAmphibian capture mark-recapture
These data represent capture mark recapture data along with associated disease status for boreal toads (Anaxyrus boreas) from Wyoming and Montana from 2004-2016 and four frog species (Rana draytonii, R. muscosa, R. pretiosa, R. sierrae) from 2001-2016.Coastal California San Francisco Gartersnake Capture-Mark-Recapture Data (2008-2013)
These data are multi-state capture histories of 273 individual San Francisco gartersnakes collected at a site before and after a portion of the site was burned. Data collection began in 2008 and continued until 2013, and the prescribed fire was applied in the fall of 2010. These data support the following paper: Halstead, B. J., Thompson, M. E., Amarello, M. , Smith, J. J., Wylie, G. D., Routman,Time to detection data for Point Reyes pond-breeding amphibians, 2017
Occupancy models provide a reliable method of estimating species distributions while accounting for imperfect detectability. The cost of accounting for false absences is that detection and nondetection surveys typically require repeated visits to a site or multiple-observer techniques. More efficient methods of collecting data to estimate detection probabilities would allow additional sites to beHydrological measurements of 300 US temporary wetlands from 2004-2014
This dataset includes hydrological measurements of 300 US temporary wetlands from 2004-2014.Occurrence of Amphibians in Northern California Coastal Dune Drainages
Many coastal dune ecosystems have been degraded by non-native dune vegetation, but these systems might still provide valuable habitat for some taxa, including amphibians. Because restoration of degraded dune systems is occurring and likely to continue, we examined the occurrence of amphibians in drainages associated with a coastal dune ecosystem degraded by invasive plants (European Beachgrass, AmCalifornia Red-Legged Frogs in Point Reyes Coastal Dune Drainages (2015)
California Red-legged Frogs (Rana draytonii) are typically regarded as inhabitants of permanent ponds, marshes, and slow-moving streams, but their ecology in other habitats, including coastal dunes, remains obscure. To avoid and minimize potential negative effects of dune restoration activities, we studied the spatial ecology, habitat selection, and survival of California Red-legged Frogs in coastMicrohabitat and Vegetation Selection by Giant Gartersnakes Associated with a Restored Marsh in California
Studies of habitat selection can reveal important patterns to guide habitat restoration and management for species of conservation concern. Giant gartersnakes (Thamnophis gigas) are endemic to the Central Valley of California, where more than 90% of their historic wetland habitat has been converted to agricultural and other uses. Information about the selection of habitats by individual giant gart - Multimedia
- Publications
Filter Total Items: 91
Estimating the survival of unobservable life stages for a declining frog with a complex life-history
Demographic models enhance understanding of drivers of population growth and inform conservation efforts to prevent population declines and extinction. For species with complex life histories, however, parameterizing demographic models is challenging because some life stages can be difficult to study directly. Integrated population models (IPMs) empower researchers to estimate vital rates for orgaAuthorsJonathan P. Rose, Sarah Kupferberg, Clara A Wheeler, Patrick M. Kleeman, Brian J. HalsteadOccurrence of a suite of stream-obligate amphibians in timberlands of Mendocino County, California, examined using environmental DNA
Stream-obligate amphibians are important indicators of ecosystem health in the Pacific Northwest, but distributional information to improve forest management is lacking in many regions. We analyzed archived DNA extracted from water samples in 60 pools in streams on private timberlands in Mendocino County, California, for 3 California Species of Special Concern—Coastal Tailed Frogs (Ascaphus truei)AuthorsBrian J. Halstead, Caren S. Goldberg, Robert B Douglas, Patrick M. Kleeman, David W UlrichHatchling emergence ecology of Ouachita map turtles (Graptemys ouachitensis) on the lower Wisconsin River, Wisconsin, USA
Despite its biological importance in shaping both individual fitness and population structure, much remains to be learned about the hatchling emergence ecology of most freshwater turtles. Here, we provide some of the first details on these early life stages for the Ouachita map turtle (Graptemys ouachitensis) obtained during 2015–2017 along the lower Wisconsin River, Iowa County, Wisconsin, and inAuthorsGregory A Geller, Gary S Casper, Brian J. HalsteadDispersal of hatchling Ouachita map turtles (Graptemys ouachitensis) from natural nests on the lower Wisconsin River, Wisconsin, USA
Despite its importance to individual fitness and population dynamics, the dispersal behaviors of most neonate freshwater turtles after nest emergence are poorly known. We studied the initial dispersal tendencies of neonate Ouachita map turtles (Graptemys ouachitensis) exiting natural nests during 2015–2017 along the Wisconsin River, Wisconsin. Overall, dispersal was nonrandom, and hatchlings largeAuthorsGregory A Geller, Gary S Casper, Brian J. HalsteadTime-to-detection occupancy methods: Performance and utility for improving efficiency of surveys
Occupancy methods propelled the quantitative study of species distributions forward by separating the observation process, or the imperfect detectability of species, from the ecological processes of interest governing species distributions. Occupancy studies come at a cost, however: the collection of additional data to account for nondetections at sites where the species is present. The most commoAuthorsBrian J. Halstead, Jonathan P. Rose, Patrick M. KleemanVirome of bat guano from nine northern California roosts
Bats are hosts to a large variety of viruses, including many capable of cross species transmissions to other mammals or humans. We characterized the virome in guano from five common bat species in 9 Northern California roosts and a pool of 5 individual bats. Genomes belonging to 14 viral families known to infect mammals and 17 viral families infecting insects or of unknown tropism were detected. NAuthorsYanpeng Li, Eda Altan, Gabriel Reyes, Brian J. Halstead, Xutao Deng, Eric DelwartDistribution of giant gartersnakes (Thamnophis gigas) in the Sacramento–San Joaquin Delta, California, 2018–2019
SummaryWe examined the occurrence of giant gartersnakes in the Sacramento–San Joaquin Delta, California, in 2018 and 2019. We made eight captures of seven giant gartersnakes (three females, four males) in 2018, and six captures of six giant gartersnakes (four females, two males) in 2019. Detection probabilities were exceedingly low despite using methods that achieve much higher detection probabiliAuthorsKristen J. Fouts, Richard Kim, Anna C. Jordan, Alexandria M. Fulton, Jonathan P. Rose, Julia S. M. Ersan, Brian J. HalsteadGiant Gartersnakes (Thamnophis gigas) exploit abundant non-native prey while maintaining their appetite for native anurans
The introductions of nonnative species can cause great change in the trophic dynamics of native species. Giant Gartersnakes, endemic predators in the Central Valley of California, are listed as threatened because of the conversion of their once vast wetland habitat to agriculture. Further contributing to this snake's changing ecology is the introduction of many nonnative prey species, resulting inAuthorsJulia Ersan, Brian J. Halstead, Erica L Wildy, Michael L. Casazza, Glenn D. WylieBatrachochytrium salamandrivorans (Bsal) not detected in an intensive survey of wild North American amphibians
The salamander chytrid fungus (Batrachochytrium salamandrivorans [Bsal]) is causing massive mortality of salamanders in Europe. The potential for spread via international trade into North America and the high diversity of salamanders has catalyzed concern about Bsal in the U.S. Surveillance programs for invading pathogens must initially meet challenges that include low rates of occurrence on the lAuthorsHardin Waddle, Daniel A. Grear, Brittany Mosher, Evan H. Campbell Grant, Michael J. Adams, Adam R. Backlin, William Barichivich, Adrianne B. Brand, Gary M. Bucciarelli, Daniel L. Calhoun, Tara Chestnut, Jon M. Davenport, Andrew E. Dietrich, Robert N. Fisher, Brad Glorioso, Brian J. Halstead, Marc P Hayes, R. Ken Honeycutt, Blake R. Hossack, Patrick M. Kleeman, Julio A. Lemos-Espinal, Jeffrey M. Lorch, Robert W. Atkinson, Erin L. Muths, Christopher Pearl, Katherine Richgels, Charles W Robinson, Mark F. Roth, Jennifer Rowe, Walter Sadinski, Brent H. Sigafus, Iga Stasiak, Samuel Sweet, Susan C. Walls, Gregory J Watkins-Colwell, C. LeAnn White, Lori A Williams, Megan E. WinzelerIntrinsic prey preference and selection of the giant gartersnake: A threatened predator in a nonnative prey-dominated community
The introduction of exotic species into an environment can introduce great change in the trophic dynamics of native species. This is of even greater concern if the native species is of conservation concern. The giant gartersnake, Thamnophis gigas, an endemic predator of the Central Valley of California and a species of conservation concern at the state and federal levels, has declined as a resultAuthorsJulia Ersan, Brian J. Halstead, Erica L Wildy, Michael L. Casazza, Glenn D. WylieIntegrating multiple data sources and multi-scale land-cover data to model the distribution of a declining amphibian
Determining the spatial scale at which landscape features influence population persistence is an important task for conservation planning. One challenge is that sampling biases confound factors that influence species occurrence and survey effort. Recent developments in Point Process Models (PPMs) enable researchers to disentangle the sampling process from ecological drivers of species' distributioAuthorsJonathan P. Rose, Brian J. Halstead, Robert N. FisherDemographic factors affecting population growth in giant gartersnakes
Demographic models provide insight into which vital rates and life stages contribute most to population growth. Integral projection models (IPMs) offer flexibility in matching model structure to a species’ demography. For many rare species, data are lacking for key vital rates, and uncertainty might dissuade researchers from attempting to build a demographic model. We present work that highlightsAuthorsJonathan P. Rose, Julia Ersan, Glenn D. Wylie, Michael L. Casazza, Brian J. Halstead - Software
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