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
Integrating multiple data sources and multi-scale land-cover data to model the distribution of a declining amphibian
Determining the spatial scale at which landscape features influence population persistence is an important task for conservation planning. One challenge is that sampling biases confound factors that influence species occurrence and survey effort. Recent developments in Point Process Models (PPMs) enable researchers to disentangle the sampling...
Rose, Jonathan P.; Halstead, Brian J.; Fisher, Robert N. Conservation 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,...
Halstead, Brian J.; Rose, Jonathan P.; Reyes, Gabriel; Wylie, Glenn D.; Casazza, Michael L. Demographic factors affecting population growth in giant gartersnakes
Demographic models provide insight into which vital rates and life stages contribute most to population growth. Integral projection models (IPMs) offer flexibility in matching model structure to a species’ demography. For many rare species, data are lacking for key vital rates, and uncertainty might dissuade researchers from attempting to build a...
Rose, Jonathan P.; Ersan, Julia; Wylie, Glenn D.; Casazza, Michael L.; Halstead, Brian J.
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...
Halstead, Brian J.; Kleeman, Patrick M.; Duarte, Adam; Rose, Jonathan P.; Urquhart, Kris; Mellison, Chad; Guadalupe, Kevin; Cota, Melanie; Van Horne, Rachel; Killion, Alexa; Ruehling, Kelsey Effect 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...
Russell, Robin E.; Halstead, Brian J.; Mosher, Brittany; Muths, Erin L.; Adams, Michael J.; Campbell Grant, Evan H.; Fisher, Robert N.; Kleeman, Patrick M.; Backlin, Adam R.; Pearl, Christopher; Honeycutt, R. Ken; Hossack, Blake R. Effects 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...
Halstead, Brian J.; Thompson, Michelle E.; Amarello, Melissa; Smith, Jeffrey J.; Wylie, Glenn D.; Routman, Eric J.; Casazza, Michael L. Time-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...
Halstead, Brian J.; Kleeman, Patrick M.; Rose, Jonathan P. Distribution, 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...
Drost, Charles A.; Fellers, Gary M.; Murphey, Thomas R.; Kleeman, Patrick M.; Halstead, Brian J.; O'Donnell, Ryan P. Identifying 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...
Campbell Grant, Evan H.; Adams, M.J.; Fisher, Robert N.; Grear, Daniel A.; Halstead, Brian J.; Hossack, Blake R.; Muths, Erin L.; Richgels, Katherine L. D.; Russell, Robin E.; Smalling, Kelly L.; Waddle, J. Hardin; Walls, Susan C.; White, C. LeAnn Integrating 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...
Rose, Jonathan P.; Wylie, Glenn D.; Casazza, Michael L.; Halstead, Brian J.
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
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...
Rose, Jonathan P.; Ersan, Julia S. M.; Reyes, Gabriel A.; Gustafson, K. Benjamin; Fulton, Alexandria M.; Fouts, Kristen J.; Wack, Raymund F.; Wylie, Glenn D.; Casazza, Michael L.; Halstead, Brian J. Reproductive 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-...
Rose, Jonathan P.; Ersan, Julia; Wylie, Glenn D.; Casazza, Michael L.; Halstead, Brian J.