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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

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Aerial view of five gulls, with grey backs and wings and white heads and tails, flying over the ocean

Birds, Bats, and Beyond: Networked Wildlife Tracking in the Southern California Bight

Seabird and bat researchers from the USGS Western Ecological Research Center are teaming up to study how flying animals move through the marine environment. This Bureau of Ocean Energy Management supported project will add 25 remote telemetry stations to the existing global Motus Wildlife Tracking System, representing the largest single investment in coastal and offshore Motus infrastructure on...
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Species Management Research Program, Western Ecological Research Center (WERC)
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Birds, Bats, and Beyond: Networked Wildlife Tracking in the Southern California Bight

Seabird and bat researchers from the USGS Western Ecological Research Center are teaming up to study how flying animals move through the marine environment. This Bureau of Ocean Energy Management supported project will add 25 remote telemetry stations to the existing global Motus Wildlife Tracking System, representing the largest single investment in coastal and offshore Motus infrastructure on...
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Bats benefit from maintaining a close-knit roosting group.

Tracking Bats and Coronaviruses

Below are the USGS 2020 Coronavirus Aid, Relief and Economic Security Act (CARES Act) research projects related to tracking bats and coronaviruses. Select tabs above for related items.
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Ecosystems Mission Area, Biological Threats and Invasive Species Research Program, Fort Collins Science Center, National Wildlife Health Center, Western Ecological Research Center (WERC)
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Tracking Bats and Coronaviruses

Below are the USGS 2020 Coronavirus Aid, Relief and Economic Security Act (CARES Act) research projects related to tracking bats and coronaviruses. Select tabs above for related items.
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SFGS

Ecology and Conservation of Reptiles

This project improves our understanding of the ecology of reptiles in California and evaluates methods of managing landscapes and these imperiled species. In particular, Dr. Brian Halstead examines the distribution and demography of reptiles to understand factors that affect where they are found and how populations change. He further explores the relationships of reptiles with their abiotic and...
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Ecosystems Mission Area, Species Management Research Program, Western Ecological Research Center (WERC)
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Ecology and Conservation of Reptiles

This project improves our understanding of the ecology of reptiles in California and evaluates methods of managing landscapes and these imperiled species. In particular, Dr. Brian Halstead examines the distribution and demography of reptiles to understand factors that affect where they are found and how populations change. He further explores the relationships of reptiles with their abiotic and...
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Image: California Red-legged Frog

Ecology and Conservation of Amphibians in Northern California

This project improves our understanding of the ecology of amphibians in northern California and evaluates methods of managing landscapes and these imperiled species. In particular, Dr. Brian Halstead examines the distribution and demography of amphibians to understand factors that affect where amphibians are found and how populations change. He further explores the relationships of amphibians with...
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Ecosystems Mission Area, Biological Threats and Invasive Species Research Program, Species Management Research Program, Western Ecological Research Center (WERC)
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Ecology and Conservation of Amphibians in Northern California

This project improves our understanding of the ecology of amphibians in northern California and evaluates methods of managing landscapes and these imperiled species. In particular, Dr. Brian Halstead examines the distribution and demography of amphibians to understand factors that affect where amphibians are found and how populations change. He further explores the relationships of amphibians with...
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hoary bat

Bat Research in California

The primary goal of this bat research program is to develop projects that increase our understanding of basic ecology and natural history of western bat species, while simultaneously providing needed data to inform conservation measures and management decisions in the West. Dr. Brian Halstead, together with Gabriel Reyes, studies the habitat and resource selection, movement ecology, demography...
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Ecosystems Mission Area, Biological Threats and Invasive Species Research Program, Species Management Research Program, Western Ecological Research Center (WERC)
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Bat Research in California

The primary goal of this bat research program is to develop projects that increase our understanding of basic ecology and natural history of western bat species, while simultaneously providing needed data to inform conservation measures and management decisions in the West. Dr. Brian Halstead, together with Gabriel Reyes, studies the habitat and resource selection, movement ecology, demography...
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Photo of waterbirds feeding at a flooded agricultural field.

Dixon Field Station

WERC scientists at the Dixon Field Station conduct studies from the San Francisco Bay-Delta in California to the Great Basin spanning California and Nevada.
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Western Ecological Research Center (WERC)
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Dixon Field Station

WERC scientists at the Dixon Field Station conduct studies from the San Francisco Bay-Delta in California to the Great Basin spanning California and Nevada.
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Filter Total Items: 25

Multi-State Occurrence Data and Predictors for Amphibians in Yosemite National Park (2007-2021)

These data include field-collected observations of the occurrence of adult and larval amphibians at 174 sites in 14 watersheds at Yosemite National Park from 2007 through 2021. Also included in the data are potential variables affecting site occurrence, probability of reproduction, and probability of detection of amphibians, including static site-specific variables like site size and elevation, an
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Western Ecological Research Center (WERC)

Data to Fit an Occupancy Model to Trapping Data for the Northwestern Pond Turtle and Red-Eared Slider in the Sacramento Valley (2018) and Sacramento-San Joaquin River Delta (2019)

These data represent the results of trapping efforts for native northwestern pond turtles (Actinemys marmorata) and non-native red-eared sliders (Trachemys scripta elegans) in wetlands and irrigation canals in agricultural regions of the Sacramento Valley in 2018 and the Sacramento-San Joaquin River Delta in 2019. In addition to detection data for these two turtle species, the dataset includes hab
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Western Ecological Research Center (WERC)

USGS Occupancy Surveys for Dixie Valley Toads, Anaxyrus williamsi, in Churchill County, Nevada from April 2018 to May 2021

Desert spring wetlands host many endemic species that require aquatic habitat and are isolated by the surrounding xeric terrestrial habitat. The Dixie Valley Toad (Anaxyrus williamsi) is a recently described anuran species endemic to desert spring wetlands in the Dixie Valley, Churchill County, Nevada, USA. Given this species was only recently recognized as distinct from Anaxyrus boreas, little is
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Western Ecological Research Center (WERC)

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.
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Western Ecological Research Center (WERC)

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 a
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Western Ecological Research Center (WERC)

Giant 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 calculated
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Western Ecological Research Center (WERC)

Growth 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 fo
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Western Ecological Research Center (WERC)

Western 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 la
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Western Ecological Research Center (WERC)

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 genetic
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Western Ecological Research Center (WERC)

Northwestern 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.
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Western Ecological Research Center (WERC)

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.
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Western Ecological Research Center (WERC)

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.
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Western Ecological Research Center (WERC)
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Filter Total Items: 83

Survival and establishment of captive-reared and translocated giant gartersnakes after release

Many imperiled species face increasing extinction risk that requires interventional management like translocation or captive rearing. The use of translocations to successfully restore or create populations requires that animals survive at recipient sites, information that is often lacking for imperiled species and that can be risky to acquire if not obtained before a species has dwindled in number
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Ecosystems Mission Area, Western Ecological Research Center (WERC)

Sierra Nevada amphibians demonstrate stable occupancy despite precipitation volatility in the early 21st Century

Climate can have a strong influence on species distributions, and amphibians with different life histories might be affected by annual variability in precipitation in different ways. The Sierra Nevada of California, United States, experienced some of the driest and wettest years on record in the early 21st Century, with variability in annual precipitation predicted to increase with climate change.
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Ecosystems Mission Area, Western Ecological Research Center (WERC)

Are canned sardines or dry cat food more effective as bait for capturing Northwestern Pond Turtles (Actinemys marmorata) and Red-eared Sliders (Trachemys scripta elegans)?

During an occupancy study of Northwestern Pond Turtles (Actinemys marmorata) and Red-eared Sliders (Trachemys scripta elegans) in California’s Sacramento Valley in 2018, we tested the relative effectiveness of 2 bait types: sardines packed in soybean oil and Meow Mix® Original Choice dry cat food. We sampled 116 sites with 2 traps each: one baited with sardines and one baited with dry cat food. Sa
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Ecosystems Mission Area, Western Ecological Research Center (WERC)

Hot, wet and rare: Modelling the occupancy dynamics of the narrowly distributed Dixie Valley toad

Context: Small population sizes and no possibility of metapopulation rescue put narrowly distributed endemic species under elevated risk of extinction from anthropogenic change. Desert spring wetlands host many endemic species that require aquatic habitat and are isolated by the surrounding xeric terrestrial habitat.Aims: We sought to model the occupancy dynamics of the Dixie Valley toad (Anaxyrus
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Ecosystems Mission Area, Western Ecological Research Center (WERC)

Optimizing survey design for shasta salamanders (Hydromantes spp.) to estimate occurrence in little-studied portions of their range

Shasta salamanders (collectively, Hydromantes samweli, H. shastae, and H. wintu; hereafter, Shasta salamander) are endemic to northern California in the general vicinity of Shasta Lake reservoir. Although generally associated with limestone, they have repeatedly been found in association with other habitats, calling into question the distribution of the species complex. Further limiting our knowle
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Ecosystems Mission Area, Patuxent Wildlife Research Center, Eastern Ecological Science Center, Western Ecological Research Center (WERC)

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 specie
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Ecosystems Mission Area, Western Ecological Research Center (WERC)

Integrating 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–r
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Ecosystems Mission Area, Western Ecological Research Center (WERC)

Looking 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 prote
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Ecosystems Mission Area, Western Ecological Research Center (WERC)

Multi-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 la
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Ecosystems Mission Area, Western Ecological Research Center (WERC)

Projecting 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 a
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Ecosystems Mission Area, Western Ecological Research Center (WERC)

Increased 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 growth
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Ecosystems Mission Area, Wetland and Aquatic Research Center

Conservation 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,
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Ecosystems Mission Area, Western Ecological Research Center (WERC)

Code to analyze multi-state, multi-scale dynamic occupancy models for amphibians in Yosemite National Park

The purpose of this study was to evaluate how extreme variation in precipitation in the Sierra Nevada of California, USA, in the early 21st Century affected adult occupancy and the probability of reproduction of amphibians. The study used a 15-year data set to relate site characteristics to initial probability of occurrence of adults, and additional site-specific and dynamic (e.g., weather) variab
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Western Ecological Research Center (WERC)

Code to analyze survival data for Giant gatersnakes, Thamnophis gigas in Sacramento County, California from 2018 to 2021

The purpose of this study was to estimate the survival of giant gartersnakes (Thamnophis gigas) prior to and following translocation, as well as to evaluate the use of captive rearing as a conservation tool for giant gartersnakes. We used Kaplan-Meier and Cox Proportional Hazards models to estimate survival rates and estimate the effects of group identity (marsh donor, rice donor, and translocatio
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Western Ecological Research Center (WERC)

Code to Analyze Occupancy Data for Dixie Valley Toads, Anaxyrus williamsi in Churchill County, Nevada from 2018 to 2021

-R code to create and fit dynamic occupancy models to Dixie Valley Toad survey data in JAGS and produce useful summaries of model results. This script will perform the Gibbs Variable Selection (GVS) using the initial set of environmental covariates, and then fit the "final" model using only important environmental covariates. The dynamic occupancy model is adapted from the model publishe
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Western Ecological Research Center (WERC)

Code to analyze Capture-Mark-Recapture data of San Francisco gartersnakes (Thamnophis sirtalis tetrataenia)

Code files "growth_analysis.R" -An R script to fit the von Bertalanffy growth model to growth data from San Francisco gartersnakes. The von Bertalanffy growth model is fit using JAGS software (Plummer 2003), and is based on the model presented in Armstrong and Brooks (2013). "survival_analysis.R" -An R script to fit the robust-design Cormack-Jolly-Seber model to capture-mark-
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Western Ecological Research Center (WERC)
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WERC Scientists Find that Threatened Snakes Depend on Agriculture (TWS Wildlife News)

SACRAMENTO – A new study shows how giant gartersnakes use Central Valley rice fields

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A Unified Research Strategy for Disease Management

As wildlife diseases increase globally, an understanding of host-pathogen relationships can elucidate avenues for management and improve conservation...

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