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
Realized detection and capture probabilities for giant gartersnakes (Thamnophis gigas) using modified floating aquatic funnel traps
A preliminary investigation of the variables affecting the distribution of giant gartersnakes (Thamnophis gigas) in the Sacramento Valley, California
A conceptual model for site-level ecology of the giant gartersnake (Thamnophis gigas) in the Sacramento Valley, California
Literature review of giant gartersnake (Thamnophis gigas) biology and conservation
Defining population structure and genetic signatures of decline in the giant garter snake (Thamnophis gigas): implications for conserving threatened species within highly altered landscapes
Terrestrial ecology of semi-aquatic giant gartersnakes (Thamnophis gigas)
Twenty-five years of monitoring a Townsend's Big-Eared Bat (Corynorhinus townsendii) maternity roost
In situ effects of pesticides on amphibians in the Sierra Nevada
A hierarchical integrated population model for greater sage-grouse (Centrocercus urophasianus) in the Bi-State Distinct Population Segment, California and Nevada
Ghost of habitat past: historic habitat affects the contemporary distribution of giant garter snakes in a modified landscape.
Effects of prescribed fire on Coluber constrictor Mormon in coastal San Mateo County, California
Evaluating greater sage-grouse seasonal space use relative to leks: Implications for surface use designations in sagebrush ecosystems
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Realized detection and capture probabilities for giant gartersnakes (Thamnophis gigas) using modified floating aquatic funnel traps
Executive Summary Rigorous analysis and management of animal populations requires that observers account for limitations inherent to the detection of those populations and the individuals within them. Researchers are usually unable to see every individual of a population or to even detect some entire populations. Ignoring this imperfect detectability can bias estimates of population characteristicAuthorsBrian J. Halstead, Shannon M. Skalos, Michael L. Casazza, Glenn D. WylieA preliminary investigation of the variables affecting the distribution of giant gartersnakes (Thamnophis gigas) in the Sacramento Valley, California
Giant gartersnakes (Thamnophis gigas) comprise a species of rare, semi-aquatic snake precinctive to the Central Valley of California. Because of the loss of more than 90% of their natural habitat, giant gartersnakes are listed as Threatened by the United States and California endangered species acts. Little is known, however, about the distribution of giant gartersnakes in the Sacramento Valley, wAuthorsBrian J. Halstead, Shannon M. Skalos, Michael L. Casazza, Glenn D. WylieA conceptual model for site-level ecology of the giant gartersnake (Thamnophis gigas) in the Sacramento Valley, California
Giant gartersnakes (Thamnophis gigas) comprise a species of semi-aquatic snakes precinctive to marshes in the Central Valley of California (Hansen and Brode, 1980; Rossman and others, 1996). Because more than 90 percent of their historical wetland habitat has been converted to other uses (Frayer and others, 1989; Garone, 2007), giant gartersnakes have been listed as threatened by the State of CaliAuthorsBrian J. Halstead, Glenn D. Wylie, Michael L. Casazza, Eric C. Hansen, Rick D. Scherer, Laura C. PattersonLiterature review of giant gartersnake (Thamnophis gigas) biology and conservation
This report reviews the available literature on giant gartersnakes (Thamnophis gigas) to compile existing information on this species and identify knowledge gaps that, if addressed, would help to inform conservation efforts for giant gartersnakes. Giant gartersnakes comprise a species of semi-aquatic snake precinctive to wetlands in the Central Valley of California. The diversion of surface wateAuthorsBrian J. Halstead, Glenn D. Wylie, Michael L. CasazzaDefining population structure and genetic signatures of decline in the giant garter snake (Thamnophis gigas): implications for conserving threatened species within highly altered landscapes
Anthropogenic habitat fragmentation can disrupt the ability of species to disperse across landscapes, which can alter the levels and distribution of genetic diversity within populations and negatively impact long-term viability. The giant gartersnake (Thamnophis gigas) is a state and federally threatened species that historically occurred in the wetland habitats of California’s Great Central ValleAuthorsDustin A. Wood, Brian J. Halstead, Michael L. Casazza, Eric C. Hansen, Glenn D. Wylie, Amy G. VandergastTerrestrial ecology of semi-aquatic giant gartersnakes (Thamnophis gigas)
Wetlands are a vital component of habitat for semiaquatic herpetofauna, but for most species adjacent terrestrial habitats are also essential. We examined the use of terrestrial environments by Giant Gartersnakes (Thamnophis gigas) to provide behavioral information relevant to conservation of this state and federally listed threatened species. We used radio telemetry data collected 1995–2011 fromAuthorsBrian J. Halstead, Shannon M. Skalos, Glenn D. Wylie, Michael L. CasazzaTwenty-five years of monitoring a Townsend's Big-Eared Bat (Corynorhinus townsendii) maternity roost
A Corynorhinus townsendii maternity roost located in an abandoned ranch house in central California was monitored for 25 y. Prior to the discovery of the bats in 1987, the house was broken into regularly and disturbance levels were quite high. Upon discovery of the roost, the house was fortified and vandalism was greatly reduced. The number of females and the number of volant young greatly increasAuthorsGary M. Fellers, Brian J. HalsteadIn situ effects of pesticides on amphibians in the Sierra Nevada
For more than 20 years, conservationists have agreed that amphibian populations around the world are declining. Results obtained through laboratory or mesocosm studies and measurement of contaminant concentrations in areas experiencing declines have supported a role of contaminants in these declines. The current study examines the effects of contaminant exposure to amphibians in situ in areas actuAuthorsDonald W. Sparling, John W. Bickham, Deborah Cowman, Gary M. Fellers, Thomas E. Lacher, Cole W. Matson, Laura McConnellA hierarchical integrated population model for greater sage-grouse (Centrocercus urophasianus) in the Bi-State Distinct Population Segment, California and Nevada
Greater sage-grouse (Centrocercus urophasianus, hereafter referred to as “sage-grouse”) are endemic to sagebrush (Artemisia spp.) ecosystems throughout Western North America. Populations of sage-grouse have declined in distribution and abundance across the range of the species (Schroeder and others, 2004; Knick and Connelly, 2011), largely as a result of human disruption of sagebrush communities (AuthorsPeter S. Coates, Brian J. Halstead, Erik J. Blomberg, Brianne Brussee, Kristy B. Howe, Lief Wiechman, Joel Tebbenkamp, Kerry P. Reese, Scott C. Gardner, Michael L. CasazzaGhost of habitat past: historic habitat affects the contemporary distribution of giant garter snakes in a modified landscape.
Historic habitat conditions can affect contemporary communities and populations, but most studies of historic habitat are based on the reduction in habitat extent or connectivity. Little is known about the effects of historic habitat on contemporary species distributions when historic habitat has been nearly completely removed, but species persist in a highly altered landscape. More than 93% of thAuthorsBrian J. Halstead, Glenn D. Wylie, Michael L. CasazzaEffects of prescribed fire on Coluber constrictor Mormon in coastal San Mateo County, California
Although prescribed burns are used in many locations where reptiles are present, the effects of fire on reptiles are poorly understood. our objective was to determine the effects of prescribed fire on the Western yellow-bellied racer, Coluber constrictor mormon, at a study site in coastal san Mateo county, california. We sampled an unburned site and an adjacent prescribed burn site two to five yeaAuthorsMichelle E. Thompson, Brian J. Halstead, Glenn D. Wylie, Melissa Amarello, Jeffrey J. Smith, Michael L. Casazza, Eric J. RoutmanEvaluating greater sage-grouse seasonal space use relative to leks: Implications for surface use designations in sagebrush ecosystems
The development of anthropogenic structures, especially those related to energy resources, in sagebrush ecosystems is an important concern among developers, conservationists, and land managers in relation to greater sage-grouse (Centrocercus urophasianus; hereafter, sage-grouse) populations. Sage-grouse are dependent on sagebrush ecosystems to meet their seasonal life-phase requirements, and reseaAuthorsMichael L. Casazza, Peter S. Coates - Software
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