Brian Halstead
Biography
Dr. Brian Halstead's research 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
- B.S. in Biology, Carroll College (Waukesha, WI), 1999
- Ph.D. in Biology, University of South Florida, 2008
Science and Products
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...
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...
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...
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.
Water 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...
Halstead, Brian J.; Kleeman, Patrick M.; Rose, Jonathan P.; Fouts, Kristen J When 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...
Kim, Richard; Halstead, Brian J.; Routman, Eric J.; Anderson, Julie Estimating the survival of unobservable life stages for a declining frog with a complex life-history
Demographic models enhance understanding of drivers of population growth and inform conservation efforts to prevent population declines and extinction. For species with complex life histories, however, parameterizing demographic models is challenging because some life stages can be difficult to study directly. Integrated population models (IPMs)...
Rose, Jonathan P.; Kupferberg, Sarah; Wheeler, Clara A; Kleeman, Patrick M.; Halstead, Brian J. Time-to-detection occupancy methods: Performance and utility for improving efficiency of surveys
Occupancy methods propelled the quantitative study of species distributions forward by separating the observation process, or the imperfect detectability of species, from the ecological processes of interest governing species distributions. Occupancy studies come at a cost, however: the collection of additional data to account for nondetections at...
Halstead, Brian J.; Rose, Jonathan P.; Kleeman, Patrick M. Hatchling emergence ecology of Ouachita map turtles (Graptemys ouachitensis) on the lower Wisconsin River, Wisconsin, USA
Despite its biological importance in shaping both individual fitness and population structure, much remains to be learned about the hatchling emergence ecology of most freshwater turtles. Here, we provide some of the first details on these early life stages for the Ouachita map turtle (Graptemys ouachitensis) obtained during 2015–2017 along the...
Geller, Gregory A; Casper, Gary S; Halstead, Brian J. Occurrence of a suite of stream-obligate amphibians in timberlands of Mendocino County, California, examined using environmental DNA
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 in streams on private timberlands in Mendocino County, California, for 3 California Species of...
Halstead, Brian J.; Goldberg, Caren S.; Douglas, Robert B; Kleeman, Patrick M.; Ulrich, David W Dispersal of hatchling Ouachita map turtles (Graptemys ouachitensis) from natural nests on the lower Wisconsin River, Wisconsin, USA
Despite its importance to individual fitness and population dynamics, the dispersal behaviors of most neonate freshwater turtles after nest emergence are poorly known. We studied the initial dispersal tendencies of neonate Ouachita map turtles (Graptemys ouachitensis) exiting natural nests during 2015–2017 along the Wisconsin River, Wisconsin....
Geller, Gregory A; Casper, Gary S; Halstead, Brian J. Virome of bat guano from nine northern California roosts
Bats are hosts to a large variety of viruses, including many capable of cross species transmissions to other mammals or humans. We characterized the virome in guano from five common bat species in 9 Northern California roosts and a pool of 5 individual bats. Genomes belonging to 14 viral families known to infect mammals and 17 viral families...
Li, Yanpeng; Altan, Eda; Reyes, Gabriel; Halstead, Brian J.; Deng, Xutao; Delwart, Eric
Distribution of giant gartersnakes (Thamnophis gigas) in the Sacramento–San Joaquin Delta, California, 2018–2019
SummaryWe examined the occurrence of giant gartersnakes in the Sacramento–San Joaquin Delta, California, in 2018 and 2019. We made eight captures of seven giant gartersnakes (three females, four males) in 2018, and six captures of six giant gartersnakes (four females, two males) in 2019. Detection probabilities were exceedingly low...
Fouts, Kristen J.; Kim, Richard; Jordan, Anna C.; Fulton, Alexandria M.; Rose, Jonathan P.; Ersan, Julia S. M.; Halstead, Brian J. Giant Gartersnakes (Thamnophis gigas) exploit abundant non-native prey while maintaining their appetite for native anurans
The introductions of nonnative species can cause great change in the trophic dynamics of native species. Giant Gartersnakes, endemic predators in the Central Valley of California, are listed as threatened because of the conversion of their once vast wetland habitat to agriculture. Further contributing to this snake's changing ecology is the...
Ersan, Julia; Halstead, Brian J.; Wildy, Erica L; Casazza, Michael L.; Wylie, Glenn D. Batrachochytrium salamandrivorans (Bsal) not detected in an intensive survey of wild North American amphibians
The salamander chytrid fungus (Batrachochytrium salamandrivorans [Bsal]) is causing massive mortality of salamanders in Europe. The potential for spread via international trade into North America and the high diversity of salamanders has catalyzed concern about Bsal in the U.S. Surveillance programs for invading pathogens must initially meet...
Waddle, Hardin; Grear, Daniel A.; Mosher, Brittany; Campbell Grant, Evan H.; Adams, Michael J.; Backlin, Adam R.; Barichivich, William; Brand, Adrianne B.; Bucciarelli, Gary M.; Calhoun, Daniel L.; Chestnut, Tara; Davenport, Jon M.; Dietrich, Andrew E.; Fisher, Robert N.; Glorioso, Brad; Halstead, Brian J.; Hayes, Marc P; Honeycutt, R. Ken; Hossack, Blake R.; Kleeman, Patrick M.; Lemos-Espinal, Julio A; Lorch, Jeffrey M.; Atkinson, Robert W.; Muths, Erin L.; Pearl, Christopher; Richgels, Katherine; Robinson, Charles W; Roth, Mark F.; Rowe, Jennifer; Sadinski, Walter; Sigafus, Brent H.; Stasiak, Iga; Sweet, Samuel; Walls, Christopher B.; Watkins-Colwell, Gregory J; White, C. LeAnn; Williams, Lori A; Winzeler, Megan E. Intrinsic prey preference and selection of the giant gartersnake: A threatened predator in a nonnative prey-dominated community
The introduction of exotic species into an environment can introduce great change in the trophic dynamics of native species. This is of even greater concern if the native species is of conservation concern. The giant gartersnake, Thamnophis gigas, an endemic predator of the Central Valley of California and a species of conservation concern at...
Ersan, Julia; Halstead, Brian J.; Wildy, Erica L; Casazza, Michael L.; Wylie, Glenn D.
USGS Science in Point Reyes National Seashore (California)
Interviews with staff at Point Reyes National Seashore tell how this National Park Service unit uses USGS science to educate visitors, and manage the park.
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
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 efficacy. Amphibians are among the most threatened groups of wildlife, and disease is a major factor in global amphibian declines.