Mike Casazza's research program at the Dixon Field Station focuses on the ecology of threatened and endangered species in a variety of ecosystems. This includes primary ecological research on the endangered California Ridgway's Rail in SF Bay, the endangered San Francisco Gartersnake, the threatened Giant Gartersnake in the Central Valley of California, the California state-listed Greater Sandhill Crane, and the Greater Sage-Grouse. Mike Casazza's research has targeted studies which provide critical species information to land managers responsible for maintaining diverse and healthy wildlife populations while trying to help recover special status species. Understanding key life history traits of special status species can lead to management options promoting species recovery.
Mike Casazza's research team at Dixon employs a multi-disciplinary approach to all of their work including participation on several collaborative efforts. They participated in the San Francisco Bay Goals Project beginning in 1995 and culminating in 2000 with a vision of the habitat needed to sustain healthy fish and wildlife populations in and around San Francisco Bay. They are currently serving on the Great Basin Integrated Landscape Monitoring (GBILM) Team for USGS to help link ecosystem drivers to on the ground monitoring programs. In addition, Mike Casazza is a co-investigator on a Sagebrush Ecosystem project examining the impacts of livestock grazing on sagebrush habitats in coordination with principal investigators from two other Science Centers. Bridging the gap between population biology and landscape level management is a primary goal of their research team’s effort. Current animal handling permits include: California State Collecting Permit, Federal Banding Permit, Authorization to capture and mark the federally listed (threatened) giant garter snake and endangered California Ridgway's rail in addition to other non-sensitive species. Mike Casazza has wide-ranging experience in radio-tagging numerous animals including snakes, waterfowl, shorebirds, and other migratory and non-migratory birds.
- 1995 M.S. California State University, Sacramento Thesis: Habitat use and movement of Northern Pintails wintering in Suisun Marsh, CA
- 1988 B.S. Wildlife Biology, U.C. Davis
Science and Products
The Suisun Marsh and Central Valley in California offer some of the world’s most important wetland habitats for waterfowl in the Pacific Flyway. Mike Casazza and USGS WERC biologists are providing the science to support and evaluate waterfowl populations and habitat management in North America.
The Ridgway’s rail is a federal and state listed endangered species that occurs in wetlands along the Pacific Coast and from the Lower Colorado River drainage to southern Baja California. Three subspecies of Ridgway’s rail are found within the United States: the California Ridgway’s Rail, Yuma Ridgway’s rail, and Light-footed Ridgway’s rail. All three subspecies have declined since 1900 as a...
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.
Findings from a Preliminary Investigation of the Effects of Aquatic Habitat (Water) Availability on Giant Gartersnake (Thamnophis gigas) Demography and Reproduction 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.
Distribution and demography of San Francisco gartersnakes (Thamnophis sirtalis tetrataenia) at Mindego Ranch, Russian Ridge Open Space Preserve, San Mateo County, California
San Francisco gartersnakes (Thamnophis sirtalis tetrataenia) are a subspecies of common gartersnakes endemic to the San Francisco Peninsula of northern California. Because of habitat loss and collection for the pet trade, San Francisco gartersnakes were listed as endangered under the precursor to the Federal Endangered Species Act. A population of...Kim, Richard; Halstead, Brian J.; Wylie, Glenn D.; Casazza, Michael L.
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...Rose, Jonathan P.; Ersan, Julia S. M.; Wylie, Glenn D.; Casazza, Michael L.; Halstead, Brian J.
The 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...Coates, Peter S.; Prochazka, Brian G.; Ricca, Mark A.; Halstead, Brian J.; Casazza, Michael L.; Blomberg, Erik J.; Brussee, Brianne E.; Wiechman, Lief; Tebbenkamp, Joel; Gardner, Scott C.; Reese, Kerry P.
Lessons from the past: isotopes of an endangered rail as indicators of underlying change to tidal marsh habitats
Introduction: Tidal marsh systems along the Pacific coast of the United States have experienced substantial stress and loss of area and ecosystem function, which we examined by using the endangered California Ridgway’s Rail, Rallus obsoletus obsoletus (‘rail’) as an indicator of its tidal marsh habitat in the San Francisco Estuary....Merritt, Angela M.; Casazza, Michael L.; Overton, Cory T.; Takekawa, John Y.; Hahn, Thomas P.; Hull, Joshua M.
Behavioral 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...Reyes, Gabriel A.; Halstead, Brian J.; Rose, Jonathan P.; Ersan, Julia S. M.; Jordan, Anna C.; Essert, Allison M.; Fouts, Kristen J.; Fulton, Alexandria M.; Gustafson, K. Benjamin; Wack, Raymund F.; Wylie, Glenn D.; Casazza, Michael L.
Surveillance for highly pathogenic influenza A viruses in California during 2014–2015 provides insights into viral evolutionary pathways and the spatiotemporal extent of viruses in the Pacific Americas Flyway
We used surveillance data collected in California before, concurrent with, and subsequent to an outbreak of highly pathogenic (HP) clade 184.108.40.206 influenza A viruses (IAVs) in 2014–2015 to (i) evaluate IAV prevalence in waterfowl, (ii) assess the evidence for spill-over infections in marine mammals and (iii) genetically characterize low-pathogenic...Ramey, Andrew M.; Hill, Nichola J.; Cline, Troy; Plancarte, Magdalena; De La Cruz, Susan; Casazza, Michael L.; Ackerman, Joshua T.; Fleskes, Joseph; Vickers, T. Winston; Reeves, Andrew; Gulland, Frances; Fontaine, Christine; Prosser, Diann J.; Runstadler, Jonathan; Boyce, Walter M.
An 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...Halstead, Brian J.; Wood, Dustin A.; Bowen, Lizabeth; Waters, Shannon C.; Vandergast, Amy G.; Ersan, Julia S.; Skalos, Shannon M.; Casazza, Michael L.
Greater sage-grouse (Centrocercus urophasianus) nesting and brood-rearing microhabitat in Nevada and California—Spatial variation in selection and survival patterns
Greater sage-grouse (Centrocercus urophasianus; hereinafter, "sage-grouse") are highly dependent on sagebrush (Artemisia spp.) dominated vegetation communities for food and cover from predators. Although this species requires the presence of sagebrush shrubs in the overstory, it also inhabits a broad geographic distribution with significant...Coates, Peter S.; Brussee, Brianne E.; Ricca, Mark A.; Dudko, Jonathan E.; Prochazka, Brian G.; Espinosa, Shawn P.; Casazza, Michael L.; Delehanty, David J.
Using object-based image analysis to conduct high-resolution conifer extraction at regional spatial scales
The distribution and abundance of pinyon (Pinus monophylla) and juniper (Juniperus osteosperma, J. occidentalis) trees (hereinafter, "pinyon-juniper") in sagebrush (Artemisia spp.) ecosystems of the Great Basin in the Western United States has increased substantially since the late 1800s. Distributional expansion and infill of pinyon-juniper into...Coates, Peter S.; Gustafson, K. Benjamin; Roth, Cali L.; Chenaille, Michael P.; Ricca, Mark A.; Mauch, Kimberly; Sanchez-Chopitea, Erika; Kroger, Travis J.; Perry, William M.; Casazza, Michael L.
Patterns in Greater Sage-grouse population dynamics correspond with public grazing records at broad scales
Human land use, such as livestock grazing, can have profound yet varied effects on wildlife interacting within common ecosystems, yet our understanding of land-use effects is often generalized from short-term, local studies that may not correspond with trends at broader scales. Here we used public land records to characterize livestock grazing...Monroe, Adrian; Aldridge, Cameron L.; Assal, Timothy J.; Veblen, Kari E.; Pyke, David A.; Casazza, Michael L.
Pinyon and juniper encroachment into sagebrush ecosystems impacts distribution and survival of greater sage-grouse
In sagebrush (Artemisia spp.) ecosystems, encroachment of pinyon (Pinus spp.) and juniper (Juniperus spp.; hereafter, “pinyon-juniper”) trees has increased dramatically since European settlement. Understanding the impacts of this encroachment on behavioral decisions, distributions, and population dynamics of greater sage-grouse (Centrocercus...Coates, Peter S.; Prochazka, Brian; Ricca, Mark; Gustafson, K. Ben; Ziegler, Pilar T.; Casazza, Michael L.
In the future of wildlife tracking, sea otters have their own social network.
Livestock grazing effects on sage-grouse: study identifies options to sustain ranching and help wildlife
Effects of livestock grazing on greater sage-grouse populations can be positive or negative depending on the amount of grazing and when grazing occurs, according to research published today in Ecological Applications. The research was conducted by scientists from the United States Geological Survey, Colorado State University and Utah State University.
Slowing fire-related population declines in greater sage-grouse in the Great Basin over the next 30 years may depend on the intensity of fire suppression efforts in core breeding areas and long-term patterns of precipitation, according to a just-published USGS-led study.