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 are recognized as some of the world’s most important wetland habitat because it provides critical breeding and wintering habitat for many waterfowl in the Pacific Flyway. Mike Casazza and USGS WERC biologists are providing necessary scientific information to support and evaluate waterfowl populations and habitat management in North America.
Relevance to USGS missions: To provide information to guide the Central Valley Joint Venture (CVJV) and other conservation programs in planning and implementing conservation efforts to support migratory waterfowl and the diversity of waterfowl habitats in California and other regions within the Pacific Flyway. This information will improve planning and implementation of CVJV and other North American Waterfowl Management Plan (NAWMP) conservation programs and ultimately the restoration, enhancement, and management of waterfowl habitats in the Pacific Flyway.
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 result of habitat loss, with interference with tidal flow as the most common mode of habitat degradation. Critical information on this species’ movements, habitat use and survival are not well understood. Explore this project to learn more on how WERC's Mike Casazza is investigating the ecology and population dynamics of the Ridgway’s rail to inform conservation and management of this endangered species and its habitat.
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, Raymond 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 18.104.22.168 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, Andy 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.
Modeling waterfowl habitat selection in the Central Valley of California to better understand the spatial relationship between commercial poultry and waterfowl
Wildlife researchers frequently study resource and habitat selection of wildlife to understand their potential habitat requirements and to conserve their populations. Understanding wildlife spatial-temporal distributions related to habitat have other applications such as to model interfaces between wildlife and domestic food animals in order to...Matchett, Elliott L.; Casazza, Michael L.; Fleskes, Joseph; Kelman, T.; Cadena, M.; Pitesky, M.
Active 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...Halstead, Brian J.; Valcarcel, Patricia; Wylie, Glenn D.; Coates, Peter S.; Casazza, Michael L.; Rosenberg, Daniel K.
A century of landscape disturbance and urbanization of the San Francisco Bay region affects the present-day genetic diversity of the California Ridgway’s Rail (Rallus obsoletus obsoletus)
Fragmentation and loss of natural habitat have important consequences for wild populations and can negatively affect long-term viability and resilience to environmental change. Salt marsh obligate species, such as those that occupy the San Francisco Bay Estuary in western North America, occupy already impaired habitats as result of human...Wood, Dustin A.; Bui, Thuy-Vy D.; Overton, Cory T.; Vandergast, Amy; Casazza, Michael L.; Hull, Joshua M.; Takekawa, John Y.
Environmental extremes and biotic interactions facilitate depredation of endangered California Ridgway’s rail in a San Francisco Bay tidal marsh
On 23 December 2015 while performing a high tide population survey for endangered Ridgway’s rails (Rallus obsoletus obsoletus; formerly known as the California clapper rail) and other rail species at Arrowhead Marsh, Martin Luther King Jr. Regional Shoreline, Oakland, California, the authors observed a series of species interactions resulting in...Overton, Cory T.; Bobzien, Steven; Grefsrud, Marcia
In the future of wildlife tracking, sea otters have their own social network.
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.