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
Monitoring protocol development and assessment for narrowly endemic toads in Nevada, 2018
Effect of amphibian chytrid fungus (Batrachochytrium dendrobatidis) on apparent survival of frogs and toads in the western USA
Conservation reliance of a threatened snake on rice agriculture
Time-to-detection occupancy modeling: An efficient method for analyzing the occurrence of amphibians and reptiles
Effects of prescribed fire on San Francisco gartersnake survival and movement
Distribution, habitat, and population size of Island Night Lizards on San Nicolas Island, California
Identifying management-relevant research priorities for responding to disease-associated amphibian declines
Integrating growth and capture–mark–recapture models reveals size‐dependent survival in an elusive species
Findings from a preliminary investigation of the effects of aquatic habitat (water) availability on giant gartersnake (Thamnophis gigas) demography in the Sacramento Valley, California, 2014–17
Reproductive frequency and size-dependence of fecundity in the Giant Gartersnake (Thamnophis gigas)
Distribution and demography of San Francisco gartersnakes (Thamnophis sirtalis tetrataenia) at Mindego Ranch, Russian Ridge Open Space Preserve, San Mateo County, California
Multiple drivers, scales, and interactions influence southern Appalachian stream salamander occupancy
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Monitoring protocol development and assessment for narrowly endemic toads in Nevada, 2018
Several species and subspecies of toads are endemic to small spring systems in the Great Basin, and their restricted ranges and habitat extent make them vulnerable to environmental perturbations. Very little is known about several of these toad populations, so a group of stakeholders including the U.S. Geological Survey, U.S. Fish and Wildlife Service, Bureau of Land Management, Nevada DepartmentAuthorsBrian J. Halstead, Patrick M. Kleeman, Adam Duarte, Jonathan P. Rose, Kris Urquhart, Chad Mellison, Kevin Guadalupe, Melanie Cota, Rachel Van Horne, Alexa Killion, Kelsey RuehlingEffect of amphibian chytrid fungus (Batrachochytrium dendrobatidis) on apparent survival of frogs and toads in the western USA
Despite increasing interest in determining the population-level effects of emerging infectious diseases on wildlife, estimating effects of disease on survival rates remains difficult. Even for a well-studied disease such as amphibian chytridiomycosis (caused by the fungus Batrachochytrium dendrobatidis [Bd]), there are few estimates of how survival of wild hosts is affected. We applied hierarchicaAuthorsRobin E. Russell, Brian J. Halstead, Brittany Mosher, Erin L. Muths, Michael J. Adams, Evan H. Campbell Grant, Robert N. Fisher, Patrick M. Kleeman, Adam R. Backlin, Christopher Pearl, R. Ken Honeycutt, Blake R. HossackConservation reliance of a threatened snake on rice agriculture
Conservation-reliant species require perpetual management by humans to persist. But do species that persist largely in human-dominated landscapes actually require conditions maintained by humans? Because most extant populations of giant gartersnakes (Thamnophis gigas) inhabit the highly modified rice agricultural regions of the Sacramento Valley, we sought to evaluate whether giant gartersnakes arAuthorsBrian J. Halstead, Jonathan P. Rose, Gabriel Reyes, Glenn D. Wylie, Michael L. CasazzaTime-to-detection occupancy modeling: An efficient method for analyzing the occurrence of amphibians and reptiles
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 beAuthorsBrian J. Halstead, Patrick M. Kleeman, Jonathan P. RoseEffects of prescribed fire on San Francisco gartersnake survival and movement
The application of fire is prescribed for management of habitats for many plant and animal communities, but its effects on herpetofauna are diverse and remain poorly understood. To date no studies have examined the effects of prescribed fire on endangered San Francisco gartersnake (Thamnophis sirtalis tetrataenia) populations, despite a call for prescribed fire in the recovery plan for the speciesAuthorsBrian J. Halstead, Michelle E. Thompson, Melissa Amarello, Jeffrey J. Smith, Glenn D. Wylie, Eric J. Routman, Michael L. CasazzaDistribution, habitat, and population size of Island Night Lizards on San Nicolas Island, California
The Island Night Lizard (Xantusia riversiana) was removed from the federal list of threatened species in May 2014. This strongly differentiated species is endemic to 3 of the southern California Channel Islands—San Clemente, San Nicolas, and Santa Barbara. Suitable habitat for Island Night Lizards is extensive on San Clemente Island, and the species is abundant there. Habitat is limited and fragmeAuthorsCharles A. Drost, Gary M. Fellers, Thomas R. Murphey, Patrick M. Kleeman, Brian J. Halstead, Ryan P. O'DonnellIdentifying management-relevant research priorities for responding to disease-associated amphibian declines
A research priority can be defined as a knowledge gap that, if resolved, identifies the optimal course of conservation action. We (a group of geographically distributed and multidisciplinary research scientists) used tools from nominal group theory and decision analysis to collaboratively identify and prioritize information needs within the context of disease-associated amphibian decline, in orderAuthorsEvan H. Campbell Grant, M. J. Adams, Robert N. Fisher, Daniel A. Grear, Brian J. Halstead, Blake R. Hossack, Erin L. Muths, Katherine L. D. Richgels, Robin E. Russell, Kelly L. Smalling, J. Hardin Waddle, Susan C. Walls, C. LeAnn WhiteByEcosystems Mission Area, Water Resources Mission Area, Biological Threats and Invasive Species Research Program, Species Management Research Program, Eastern Ecological Science Center, Forest and Rangeland Ecosystem Science Center, Fort Collins Science Center, National Wildlife Health Center, New Jersey Water Science Center, Northern Rocky Mountain Science Center, Western Ecological Research Center (WERC), Wetland and Aquatic Research CenterIntegrating growth and capture–mark–recapture models reveals size‐dependent survival in an elusive species
Survival is a key vital rate for projecting the viability of wild populations. Estimating survival is difficult for many rare or elusive species because recapture rates of marked individuals are low, and the ultimate fate of individuals is unknown. Low recapture rates for many species have made it difficult to accurately estimate survival, and to evaluate the importance of individual and environmeAuthorsJonathan P. Rose, Glenn D. Wylie, Michael L. Casazza, Brian J. HalsteadFindings from a preliminary investigation of the effects of aquatic habitat (water) availability on giant gartersnake (Thamnophis gigas) demography in the Sacramento Valley, California, 2014–17
The giant gartersnake (Thamnophis gigas) is a semi-aquatic species of snake precinctive to the Central Valley of California. Because the Central Valley has experienced a substantial loss of wetland habitat, giant gartersnake populations are largely found in aquatic habitats associated with rice agriculture. In dry years, less water may be available for rice agriculture, resulting in less aquatic hAuthorsJonathan P. Rose, Julia S. M. Ersan, Gabriel A. Reyes, K. Benjamin Gustafson, Alexandria M. Fulton, Kristen J. Fouts, Raymund F. Wack, Glenn D. Wylie, Michael L. Casazza, Brian J. HalsteadReproductive frequency and size-dependence of fecundity in the Giant Gartersnake (Thamnophis gigas)
How reproductive output changes with age or size is a key life-history trait that can affect which demographic rates most influence population growth. Although many studies have investigated the reproductive ecology of gartersnakes, we know little about reproduction in the threatened Giant Gartersnake, Thamnophis gigas. We used X-radiography to determine reproductive status and estimated fecundityAuthorsJonathan P. Rose, Julia Ersan, Glenn D. Wylie, Michael L. Casazza, Brian J. HalsteadDistribution and demography of San Francisco gartersnakes (Thamnophis sirtalis tetrataenia) at Mindego Ranch, Russian Ridge Open Space Preserve, San Mateo County, California
San Francisco gartersnakes (Thamnophis sirtalis tetrataenia) are a subspecies of common gartersnakes endemic to the San Francisco Peninsula of northern California. Because of habitat loss and collection for the pet trade, San Francisco gartersnakes were listed as endangered under the precursor to the Federal Endangered Species Act. A population of San Francisco gartersnakes resides at Mindego RancAuthorsRichard Kim, Brian J. Halstead, Glenn D. Wylie, Michael L. CasazzaMultiple drivers, scales, and interactions influence southern Appalachian stream salamander occupancy
Understanding how factors that vary in spatial scale relate to population abundance is vital to forecasting species responses to environmental change. Stream and river ecosystems are inherently hierarchical, potentially resulting in organismal responses to fine‐scale changes in patch characteristics that are conditional on the watershed context. Here, we address how populations of two salamander sAuthorsKristen K. Cecala, John C. Maerz, Brian J. Halstead, John R. Frisch, Ted L. Gragson, Jeffrey Hepinstall-Cymerman, David S. Leigh, C. Rhett Jackson, James Peterson, Catherine M. Pringle - Software
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