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
Temperature and Relative Conductivity at Sampling Locations in the Dixie Valley, Churchill County, Nevada, 2019-2021
Time to First Detection of Northwestern Pond Turtles and Red-eared Sliders by Bait Type in the Sacramento Valley, California, 2018
Giant Gartersnake (Thamnophis gigas) Prey Preference (2014)
Growth and Capture-Mark-Recapture Data for San Francisco Gartersnakes, Thamnophis sirtalis tetrataenia, in San Mateo County, California from 2007 to 2020
Western Spadefoot Survey Data in Northern and Central California (2019)
Amphibian chytrid swab data from Mendocino County, California (2016 - 2020)
San Francisco Gartersnake (Thamnophis sirtalis tetrataenia) Genomic and Demographic Data from San Mateo County and Northeastern Santa Cruz County Collected Between 2016 - 2018
Northwestern Pond Turtle Survey Data in Northern California Forest Streams (2021)
Amphibian Chytrid Swab Data from Churchill County, Nevada (2019-2021)
Western Spadefoot Habitat Selection Based on Radio Telemetry in Orange County, California 2019
Shasta Salamanders Surveys for the Shasta-Trinity National Forest (ver. 2.0, July 2020)
Characteristics of Sites Sampled for eDNA of Amphibians in Mendocino County, California, 2016
Riparian buffers provide refugia during secondary forest succession
Diverse aging rates in ectothermic tetrapods provide insights for the evolution of aging and longevity
Integrating growth and survival models for flexible estimation of size-dependent survival in a cryptic, endangered snake
Looking ahead, guided by the past: The role of U.S. national parks in amphibian research and conservation
Multi-scale patterns in occurrence of an ephemeral pool-breeding amphibian
Projecting the remaining habitat for the western spadefoot (Spea hammondii) in heavily urbanized southern California
Increased growth rates of stream salamanders following forest harvesting
Conservation implications of spatiotemporal variation in the terrestrial ecology of Western spadefoots
A tale of two valleys: Endangered species policy and the fate of the giant gartersnake
Metal accumulation varies with life history, size, and development of larval amphibians
Water temperature and availability shape the spatial ecology of a hot springs endemic toad
When introduced prey violates trophic hierarchy: Conservation of an endangered predator
Science and Products
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Filter Total Items: 36
Temperature and Relative Conductivity at Sampling Locations in the Dixie Valley, Churchill County, Nevada, 2019-2021
These data provide temperatures and relative conductivity to determine the presence or absence of water at specific locations in Dixie Meadows, Dixie Valley, Churchill County, Nevada, 2019-2021.Time to First Detection of Northwestern Pond Turtles and Red-eared Sliders by Bait Type in the Sacramento Valley, California, 2018
These data provide the time to first detection in days of Northwestern Pond Turtles (Actinemys marmorata) and Red-eared Sliders (Trachemys scripta elegans) by trapping location and bait type in the Sacramento Valley, California, in 2018. Bait types evaluated include sardines and dry cat food. Only location, species, and bait type combinations that resulted in captures are included. These data aGiant Gartersnake (Thamnophis gigas) Prey Preference (2014)
This is an examination of the diet of a threatened snake, giant gartersnake (Thamnophis gigas). Prey preference, prey selection and prey availability (in the laboratory and the field) were measured to understand prey dynamics for better conservation of this snake. In the laboratory, olfactory trials were performed on neonate snakes and tongue-flicks, lounges and attacks were counted and calculatedGrowth and Capture-Mark-Recapture Data for San Francisco Gartersnakes, Thamnophis sirtalis tetrataenia, in San Mateo County, California from 2007 to 2020
This dataset includes records of captures of San Francisco gartersnakes (Thamnophis sirtalis tetrataenia) collected at five sites from 2007 to 2020. The data include measurements of snake snout-vent length to estimate growth patterns, snake sex, and the record of all captures of individual snakes for estimating capture probability, availability for capture, and survival. These data support the foWestern Spadefoot Survey Data in Northern and Central California (2019)
Species distributions are governed by processes occurring at multiple spatial scales. For species with complex life cycles, the needs of all life stages must be met within the dispersal limitations of the species. Multi-scale processes can be particularly important for these species, where small-scale patterns in specific habitat components can affect the distribution of one life stage, whereas laAmphibian chytrid swab data from Mendocino County, California (2016 - 2020)
This dataset includes results from external skin swabbing of Rana boylii and Dicamptodon tenebrosus to test for the fungus Batrachochytrium dendrobatidis from Fox Creek in Mendocino County, California, in 2016-2020. Morphological measurements of swabbed animals were recorded, and Rana boylii had a unique identifier (pit tag) inserted beneath their skin for identification in future capture events.San Francisco Gartersnake (Thamnophis sirtalis tetrataenia) Genomic and Demographic Data from San Mateo County and Northeastern Santa Cruz County Collected Between 2016 - 2018
Conversion and fragmentation of wildlife habitat often leads to smaller and isolated populations and can reduce a species' ability to disperse across the landscape. As a consequence, genetic drift can quickly lower genetic variation and increase vulnerability to extirpation. For species of conservation concern, quantification of population size and connectivity can clarify the influence of geneticNorthwestern Pond Turtle Survey Data in Northern California Forest Streams (2021)
These data are from joint visual encounter and environmental DNA (eDNA) surveys conducted for northwestern pond turtles (Actinemys marmorata) in streams on privately-owned timberlands in northern California.Amphibian Chytrid Swab Data from Churchill County, Nevada (2019-2021)
This dataset includes results from external skin swabbing of Anaxyrus williamsi and Lithobates catesbeianus to test for the fungus Batrachochytrium dendrobatidis from the Dixie Valley in Churchill County, Nevada, in 2019-2021.Western Spadefoot Habitat Selection Based on Radio Telemetry in Orange County, California 2019
We conducted a radio telemetry study of adult western spadefoots (Spea hammondii) at 2 sites in southern California to characterize their survival, behavior, and movements from breeding through aestivation to inform conservation and management for the species. These data support the following publication: Halstead, B.J., Baumberger, K.L., Backlin, A.R., Kleeman, P.M., Wong, M.N., Gallegos, E.Shasta Salamanders Surveys for the Shasta-Trinity National Forest (ver. 2.0, July 2020)
The Shasta salamander (Hydromantes shastae) has been petitioned for listing under the Endangered Species Act. The greatest threat to the species is likely habitat loss that will be caused by the increase in elevation of Shasta Lake that will occur with proposed increases in the height of Shasta Dam to increase water storage capacity and maintain cold water for Chinook salmon (Oncorhynchus tshawytsCharacteristics of Sites Sampled for eDNA of Amphibians in Mendocino County, California, 2016
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 within streams in private timberlands in Mendocino County, California, for 3 California Species of Special Concern - Coastal Tailed Frogs (Ascaphus - Multimedia
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Filter Total Items: 91
Riparian buffers provide refugia during secondary forest succession
AimSecondary forests regenerating from human disturbance are increasingly becoming a predominant forest type in many regions, and they play a significant role in forest community dynamics. Understanding the factors that underlie the variation in species responses during secondary succession is important for understanding community assembly and biodiversity monitoring and management. Because specieAuthorsMichelle E. Thompson, Brian J. Halstead, Maureen A. DonnellyDiverse aging rates in ectothermic tetrapods provide insights for the evolution of aging and longevity
Comparative studies of mortality in the wild are necessary to understand the evolution of aging; yet, ectothermic tetrapods are underrepresented in this comparative landscape, despite their suitability for testing evolutionary hypotheses. We present a study of aging rates and longevity across wild tetrapod ectotherms, using data from 107 populations (77 species) of nonavian reptiles and amphibiansAuthorsBeth A. Reinke, Hugo Cayuela, Fredric J. Janzen, Jean-François Lemaitre, Jean-Michel Gaillard, A. Michelle Lawing, John B. Iverson, Ditte G Christiansen, Iñigo Martínez-Solano, Gregorio Sánchez-Montes, Jorge Gutiérrez-Rodríguez, Francis L Rose, Nicola J. Nelson, Susan Keall, Alain J Crivelli, Theodoros Nazirides, Annegret Grimm-Seyfarth, Klaus Henle, Emiliano Mori, Gaëtan Guiller, Rebecca Homan, Anthony Olivier, Erin L. Muths, Blake R. Hossack, Xavier Bonnet, David Pilliod, Marieke Lettink, Tony Whitaker, Benedikt R. Schmidt, Michael G. Gardner, Marc Cheylan, Françoise Poitevin, Ana Golubović, Ljiljana Tomović, Dragan Arsovski, Richard A Griffiths, Jan W. Arntzen, Jean-Pierre Baron, Jean-François Le Galliard, Thomas Tully, Luca Luiselli, Massimo Capula, Lorenzo Rugiero, Rebecca McCaffery, Lisa A Eby, Briggs-Gonzalez; Venetia, Frank Mazzotti, David M. Pearson, Brad A. Lambert, David M. Green, Nathalie Jreidini, Claudio Angelini, Graham Pyke, Jean-Marc Thirion, Pierre Joly, Jean-Paul Léna, Tony Tucker, Col Limpus, Pauline Priol, Aurélien Besnard, Pauline Bernard, Kristin Stanford, Richard S. King, Justin M Garwood, Jaime Bosch, Franco Souza, Jaime Bertoluci, Shirley Famelli, Kurt Grossenbacher, Omar Lenzi, Kathleen Matthews, Sylvain Boitaud, Deanna H. Olson, Tim Jessop, Graeme Gillspie, Jean Clobert, Murielle Richard, Andrés Valenzuela-Sánchez, Gary M. Fellers, Patrick M. Kleeman, Brian J. Halstead, Evan H. Campbell Grant, Phillip G Byrne, Thierry Frétey, Gernard Le Garff, Pauline Levionnois, John C. Maerz, Julian Pichenot, Kurtulus Olgun, Nazan Üzüm, Aziz Avcı, Claude Miaud, Johan Elmberg, Gregory P Brown, Richard Shine, Nathan F Bendik, Lisa O'Donnell, Courtney L. Davis, Michael J Lannoo, Rochelle M Stiles, Robert M Cox, Aaron M Reedy, Daniel A. Warner, Eric Bonnaire, Kristine Grayson, Roberto Ramos-Targarona, Eyup Baskale, David J. Muñoz, John Measey, F. Andre de Villiers, Will Selman, Victor Ronget, Anne M. Bronikowski, David A W MillerIntegrating growth and survival models for flexible estimation of size-dependent survival in a cryptic, endangered snake
Estimates of demographic rates for animal populations and individuals have many applications for ecological and conservation research. In many animals, survival is size-dependent, but estimating the form of the size–survival relationship presents challenges. For elusive species with low recapture rates, individuals’ size will be unknown at many points in time. Integrating growth and capture–mark–rAuthorsJonathan P. Rose, Richard Kim, Elliot James Schoenig, Patrick C. Lien, Brian J. HalsteadLooking ahead, guided by the past: The role of U.S. national parks in amphibian research and conservation
Protected areas like national parks are essential elements of conservation because they limit human influence on the landscape, which protects biodiversity and ecosystem function. The role of national parks in conservation, however, often goes far beyond limiting human influence. The U.S. National Park Service and its system of land units contribute substantively to conservation by providing proteAuthorsBrian J. Halstead, Andrew M. Ray, Erin L. Muths, Evan H. Campbell Grant, Rob Grasso, Michael J. Adams, Kathleen Semple Delaney, Jane Carlson, Blake R. HossackMulti-scale patterns in occurrence of an ephemeral pool-breeding amphibian
Species distributions are governed by processes occurring at multiple spatial scales. For species with complex life cycles, the needs of all life stages must be met within the dispersal limitations of the species. Multi-scale processes can be particularly important for these species, where small-scale patterns in specific habitat components can affect the distribution of one life stage, whereas laAuthorsBrian J. Halstead, Jonathan P. Rose, Denise Clark, Patrick M. Kleeman, Robert N. FisherProjecting the remaining habitat for the western spadefoot (Spea hammondii) in heavily urbanized southern California
Extensive urbanization in coastal southern California has reduced natural habitat in this biodiversity hotspot. To better conserve ecological communities, state and federal agencies, along with local jurisdictions and private stakeholders, developed regional conservation plans for southern California. Although many protected areas exist within this region, the patchwork nature of these protected aAuthorsJonathan P. Rose, Brian J. Halstead, Robert H. Packard, Robert N. FisherIncreased growth rates of stream salamanders following forest harvesting
Timber harvesting can influence headwater streams by altering stream productivity, with cascading effects on the food web and predators within, including stream salamanders. Although studies have examined shifts in salamander occupancy or abundance following timber harvest, few examine sublethal effects such as changes in growth and demography. To examine the effect of upland harvesting on growthAuthorsJacquelyn C. Guzy, Brian J. Halstead, Kelly M. Halloran, Jessica A. Homyack, John D. WillsonConservation implications of spatiotemporal variation in the terrestrial ecology of Western spadefoots
Conservation of species reliant on ephemeral resources can be especially challenging in the face of a changing climate. Western spadefoots (Spea hammondii) are small burrowing anurans that breed in ephemeral pools, but adults spend the majority of their lives underground in adjacent terrestrial habitat. Western spadefoots are of conservation concern throughout their range because of habitat loss,AuthorsBrian J. Halstead, Katherine L. Baumberger, Adam R. Backlin, Patrick M. Kleeman, Monique Nicole Wong, Elizabeth Gallegos, Jonathan P. Rose, Robert N. FisherA tale of two valleys: Endangered species policy and the fate of the giant gartersnake
By the mid-20th Century, giant gartersnakes (Thamnophis gigas) had lost more than 90% of their Central Valley marsh habitat and were extirpated from more than two-thirds of their range. This massive habitat loss led to their inclusion in the inaugural list of rare species under the California Endangered Species Act (CESA). Listing under the CESA provided giant gartersnakes legal protection and mecAuthorsBrian J. Halstead, Patricia Valcarcel, Richard Kim, Anna Jordan, Jonathan P. Rose, Shannon Skalos, Gabriel Reyes, Julia Ersan, Michael L. Casazza, Allison Essert, Alexandria M FultonMetal accumulation varies with life history, size, and development of larval amphibians
Amphibian larvae are commonly used as indicators of aquatic ecosystem health because they are susceptible to contaminants. However, there is limited information on how species characteristics and trophic position influence contaminant loads in larval amphibians. Importantly, there remains a need to understand whether grazers (frogs and toads [anurans]) and predators (salamanders) provide comparablAuthorsKelly L. Smalling, Emily Bea Oja, Danielle M. Cleveland, Jon D Davenport, Collin Eagles-Smith, Evan H. Campbell Grant, Patrick M. Kleeman, Brian J. Halstead, Kenzi M Stemp, Brian J. Tornabene, Zachary J Bunnell, Blake R. HossackWater temperature and availability shape the spatial ecology of a hot springs endemic toad
Desert amphibians are limited to exploiting ephemeral resources and aestivating or to inhabiting scarce refuges of permanent water, such as springs. Understanding how amphibians use these resources is essential for their conservation. Dixie Valley Toads (Anaxyrus williamsi) are precinctive to a small system of cold and hot springs in the Dixie Valley, Nevada, USA. The toads have been petitioned foAuthorsBrian J. Halstead, Patrick M. Kleeman, Jonathan P. Rose, Kristen J FoutsWhen introduced prey violates trophic hierarchy: Conservation of an endangered predator
Introduced species often disrupt established food webs, but some native predators can come to rely on introduced prey. Understanding the net effects of the non-natives on imperiled predators is crucial for planning conservation measures. The invasive American bullfrog (Lithobates catesbeianus) can be prey, predator, and competitor for the critically endangered San Francisco garter snake (ThamnophiAuthorsRichard Kim, Brian J. Halstead, Eric J. Routman, Julie Anderson - Software
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