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
Construction and analysis of a giant gartersnake (Thamnophis gigas) population projection model
The relative importance of intrinsic and extrinsic drivers to population growth vary among local populations of Greater Sage-Grouse: An integrated population modeling approach
Spatial and temporal variability in growth of giant gartersnakes: Plasticity, precipitation, and prey
Behavioral response of giant gartersnakes (Thamnophis gigas) to the relative availability of aquatic habitat on the landscape
Population trends, survival, and sampling methodologies for a population of Rana draytonii
An evaluation of the efficacy of using environmental DNA (eDNA) to detect giant gartersnakes (Thamnophis gigas)
Occurrence of amphibians in northern California coastal dune drainages
Frogs on the beach: Ecology of California Red-legged Frogs (Rana draytonii) in coastal dune drainages
Mallard (Anas platyrhynchos) mortality and recovery rates vary by wing molt status at time of banding
Ecology of the Eastern Kingsnake (Lampropeltis getula) at Rainey Slough, Florida: A vanished Eden
Active season microhabitat and vegetation selection by giant gartersnakes associated with a restored marsh in California
Habitat selection by juvenile Mojave Desert tortoises
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Construction and analysis of a giant gartersnake (Thamnophis gigas) population projection model
The giant gartersnake (Thamnophis gigas) is a state and federally threatened species precinctive to California. The range of the giant gartersnake has contracted in the last century because its wetland habitat has been drained for agriculture and development. As a result of this habitat alteration, giant gartersnakes now largely persist in and near rice agriculture in the Sacramento Valley, becausAuthorsJonathan P. Rose, Julia S. M. Ersan, Glenn D. Wylie, Michael L. Casazza, Brian J. HalsteadThe relative importance of intrinsic and extrinsic drivers to population growth vary among local populations of Greater Sage-Grouse: An integrated population modeling approach
Consideration of ecological scale is fundamental to understanding and managing avian population growth and decline. Empirically driven models for population dynamics and demographic processes across multiple spatial scales can be powerful tools to help guide conservation actions. Integrated population models (IPMs) provide a framework for better parameter estimation by unifying multiple sources ofAuthorsPeter S. Coates, Brian G. Prochazka, Mark A. Ricca, Brian J. Halstead, Michael L. Casazza, Erik J. Blomberg, Brianne E. Brussee, Lief Wiechman, Joel Tebbenkamp, Scott C. Gardner, Kerry P. ReeseSpatial and temporal variability in growth of giant gartersnakes: Plasticity, precipitation, and prey
The growth rate of reptiles is plastic and often varies among individuals, populations, and years in response to environmental conditions. For an imperiled species, the growth rate of individual animals is an important component of demographic models, and changes in individual growth rates might precede changes in abundance. We analyzed a long-term dataset on the growth of Giant Gartersnakes (ThamAuthorsJonathan P. Rose, Brian J. Halstead, Glenn D. Wylie, Michael L. CasazzaBehavioral response of giant gartersnakes (Thamnophis gigas) to the relative availability of aquatic habitat on the landscape
Most extant giant gartersnake (Thamnophis gigas) populations persist in an agro-ecosystem dominated by rice, which serves as a surrogate to the expansive marshes lost to flood control projects and development of the Great Central Valley of California. Knowledge of how giant gartersnakes use the rice agricultural landscape, including how they respond to fallowing, idling, or crop rotations, would gAuthorsGabriel A. Reyes, Brian J. Halstead, Jonathan P. Rose, Julia S. M. Ersan, Anna C. Jordan, Allison M. Essert, Kristen J. Fouts, Alexandria M. Fulton, K. Benjamin Gustafson, Raymund F. Wack, Glenn D. Wylie, Michael L. CasazzaPopulation trends, survival, and sampling methodologies for a population of Rana draytonii
Estimating population trends provides valuable information for resource managers, but monitoring programs face trade-offs between the quality and quantity of information gained and the number of sites surveyed. We compared the effectiveness of monitoring techniques for estimating population trends of Rana draytonii (California Red-legged Frog) at Point Reyes National Seashore, California, USA, oveAuthorsGary M. Fellers, Patrick M. Kleeman, David A.W. Miller, Brian J. HalsteadAn evaluation of the efficacy of using environmental DNA (eDNA) to detect giant gartersnakes (Thamnophis gigas)
Detecting populations of rare or cryptic species is essential for their conservation. For species like giant gartersnakes (Thamnophis gigas), conventional survey methods can be expensive and inefficient. These sampling difficulties might be overcome by modern techniques that detect deoxyribonucleic acid (DNA) shed by organisms into the environment (eDNA). We evaluated the efficacy of detecting giaAuthorsBrian J. Halstead, Dustin A. Wood, Lizabeth Bowen, Shannon C. Waters, Amy G. Vandergast, Julia S. Ersan, Shannon M. Skalos, Michael L. CasazzaOccurrence 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, AmAuthorsBrian J. Halstead, Patrick M. KleemanFrogs on the beach: Ecology of California Red-legged Frogs (Rana draytonii) in coastal dune drainages
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, such as drainages among coastal dunes, remains obscure. Because coastal dune ecosystems have been degraded by development, off-highway vehicle use, stabilization, and invasive species, these unique ecosystems are the focus ofAuthorsBrian J. Halstead, Patrick M. KleemanMallard (Anas platyrhynchos) mortality and recovery rates vary by wing molt status at time of banding
Recovery (i.e., shot, retrieved, and reported) rates and daily mortality risk of 52,330 adult Mallards (Anas platyrhynchos) leg-banded during pre-molt, in-molt, or post-molt during 1985–2011 were evaluated to better understand mortality during wing molt in dynamics of the Mallard population in California, USA. Recovery rates and non-hunting mortality risk varied by molt status at time of banding aAuthorsJoseph P. Fleskes, Brian J. Halstead, Jeffrey D. Kohl, Gregory S. YarrisEcology of the Eastern Kingsnake (Lampropeltis getula) at Rainey Slough, Florida: A vanished Eden
Eastern Kingsnakes (Lampropeltis getula) are an important component and predator in herpetofaunal communities, but many Eastern Kingsnake populations have declined precipitously in the last few decades, particularly in the southeastern United States. Here, we describe an intensive capture–mark–recapture study of L. getula conducted during 1974–1978 in a canal bank–Water Hyacinth (Eichhornia crassiAuthorsJ. Steve Godley, Brian J. Halstead, Roy W. McDiarmidActive season microhabitat 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 >90% of their historical wetland habitat has been converted to agricultural and other uses. Information about the selection of habitats by individual giant gartersnakesAuthorsBrian J. Halstead, Patricia Valcarcel, Glenn D. Wylie, Peter S. Coates, Michael L. Casazza, Daniel K. RosenbergHabitat selection by juvenile Mojave Desert tortoises
Growing pressure to develop public lands for renewable energy production places several protected species at increased risk of habitat loss. One example is the Mojave desert tortoise (Gopherus agassizii), a species often at the center of conflicts over public land development. For this species and others on public lands, a better understanding of their habitat needs can help minimize negative impaAuthorsBrian D Todd, Brian J. Halstead, Lindsay P. Chiquoine, J. Mark Peaden, Kurt A. Buhlmann, Tracey D. Tuberville, Aleta Nafus - Software
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