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Cory Overton

Cory Overton is a wildlife biologist at the Western Ecological Research Center.

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Shadowy figure of birds flying through golden dusk lit cloudy sky

Waterbird Ecology and Movement in the Saline Lakes

How do changing conditions in the terminal lakes of the Great Basin effect the migratory birds that depend on them? USGS scientists investigate bird movement and habitat use to find out.
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Western Ecological Research Center (WERC), Saline Lakes Ecosystems Integrated Water Availability Assessment
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Waterbird Ecology and Movement in the Saline Lakes

How do changing conditions in the terminal lakes of the Great Basin effect the migratory birds that depend on them? USGS scientists investigate bird movement and habitat use to find out.
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Hands hold up brown goose wearing a brown GPS collar

Goose Population Dynamics in the California Central Valley and Pacific Flyway

USGS scientists and partners are studying how growing goose populations in the California Central Valley wintering areas are affecting ducks and other waterfowl.
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Species Management Research Program, Western Ecological Research Center (WERC)
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Goose Population Dynamics in the California Central Valley and Pacific Flyway

USGS scientists and partners are studying how growing goose populations in the California Central Valley wintering areas are affecting ducks and other waterfowl.
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Dozens of birds flying over grassy wetlands

Webinar: Linking Remote Sensing and Bird Behavior Data to Understand the Impacts of Drought on Waterfowl

View this webinar to learn how scientists are exploring the impacts of drought on waterfowl.
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Ecosystems Mission Area, Climate Adaptation Science Centers
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Webinar: Linking Remote Sensing and Bird Behavior Data to Understand the Impacts of Drought on Waterfowl

View this webinar to learn how scientists are exploring the impacts of drought on waterfowl.
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Dozens of birds flying over grassy wetlands

The Impact of Drought on Waterbirds and Their Wetland Habitats in California’s Central Valley

California’s Central Valley is a nexus for water resources in the state, draining the Sacramento and San Joaquin River watersheds. Urban centers, agricultural operations, and the environment all compete for limited water, and demand is expected to only increase as the population grows and agriculture intensifies. At the same time, the water supply is projected to decrease as temperatures rise, pre...
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Climate Adaptation Science Centers
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The Impact of Drought on Waterbirds and Their Wetland Habitats in California’s Central Valley

California’s Central Valley is a nexus for water resources in the state, draining the Sacramento and San Joaquin River watersheds. Urban centers, agricultural operations, and the environment all compete for limited water, and demand is expected to only increase as the population grows and agriculture intensifies. At the same time, the water supply is projected to decrease as temperatures rise, pre...
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color photograph of California coastal cliff

Effects of Sea-Level Rise and Extreme Storms on California Coastal Habitats: Part 1

In California, the near-shore area where the ocean meets the land is a highly productive yet sensitive region that supports a wealth of wildlife, including several native bird species. These saltmarshes, mudflats, and shallow bays are not only critical for wildlife, but they also provide economic and recreational benefits to local communities. Today, sea-level rise, more frequent and stronger stor
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Climate Adaptation Science Centers
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Effects of Sea-Level Rise and Extreme Storms on California Coastal Habitats: Part 1

In California, the near-shore area where the ocean meets the land is a highly productive yet sensitive region that supports a wealth of wildlife, including several native bird species. These saltmarshes, mudflats, and shallow bays are not only critical for wildlife, but they also provide economic and recreational benefits to local communities. Today, sea-level rise, more frequent and stronger stor
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Fate of Endangered Species in San Francisco Bay Tidal Marshes with Sea-Level Rise

The San Francisco Bay estuary contains the largest remaining expanse of tidal salt marshes in the western U.S. These marshes are home to a variety of federal and state protected species, such as the California clapper rail, California black rail, and the salt marsh harvest mouse. The estuary is also located on the Pacific Flyway, and is an important site for migrating and wintering birds. As clima
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Climate Adaptation Science Centers, San Francisco Bay and Sacramento-San Joaquin Delta Estuary
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Fate of Endangered Species in San Francisco Bay Tidal Marshes with Sea-Level Rise

The San Francisco Bay estuary contains the largest remaining expanse of tidal salt marshes in the western U.S. These marshes are home to a variety of federal and state protected species, such as the California clapper rail, California black rail, and the salt marsh harvest mouse. The estuary is also located on the Pacific Flyway, and is an important site for migrating and wintering birds. As clima
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Data describing habitat use and availability for wild waterfowl in California, USA

These data describe the overlap of wild waterfowl and domestic poultry operations in California, USA. These data support a paired USGS publication.
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Eastern Ecological Science Center

Movements, Used Habitats, and Available Habitats Identified using Step Selection Processes for Four Species of Waterfowl in California's Central Valley, 2016-2022

Step selection functions use animal movement patterns to estimate habitats available at each step along a movement track. These data were generated from four species of waterfowl (Anser albifrons [greater white-fronted goose], Anser caerulescens caerulescens [lesser snow goose], Anas platyrhynchos [mallard], Anas acuta [northern pintail]) using the Central Valley of California 2016 to 2022 that we
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Western Ecological Research Center (WERC)

Waterfowl GPS Observations in North America from 2015 to 2023 for Custom Wildlife Report Example for Sacramento National Wildlife Refuge

To effectively manage species and habitats at multiple scales, land managers require rapid information on wildlife use of managed areas and responses to landscape conditions and management actions. Global positioning system (GPS) tracking studies of wildlife are particularly informative to species ecology, habitat use, and conservation. Combining GPS data with administrative data, would more compr
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Western Ecological Research Center (WERC)

Bibliography of hydrological and ecological research in the Great Basin terminal lakes, USA

This database contains literature citations and associated abstracts pertaining to the ecology and hydrology of terminal lakes in the Great Basin region of the western United States. This is not meant to be an exhaustive list, nor did we perform a systematic meta-analysis; rather, literature records were included based on topical relevance.
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Forest and Rangeland Ecosystem Science Center

Data describing infection status and movement ecology of North American waterfowl

These data, which support a USGS authored manuscript, describe how active and previous previous infection with avian influenza impacts the movement ecology of several wild waterfowl species that overwinter in California. Results varied by species and demonstrate that the relationships between avian influenza infection and wild bird movements are context- and species-dependent.
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Eastern Ecological Science Center

Hourly GPS Locations, Associated Habitat Condition, and Annotated Life History State for Training Machine Learned Models of Waterfowl Daily Activity

These data represent an annotated training data for machine learned life history classification of the daily activity of dabbling ducks (f. Anatidae sf. Anatinae) using hourly GPS data. Each row of data represents a single GPS location for one of 5 species of dabbling duck. Note: the machine learned model was developed to be general across sf. Anatinae and does not include specific reference to th
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Western Ecological Research Center (WERC)

Data measuring avian influenza infection, mercury concentration, and body condition in wild waterfowl

These data represent mercury contamination, influenza infection, and body condition in 11 species of dabbling and diving ducks in the Pacific Flyway. These data support a USGS lead scientific publication.
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Eastern Ecological Science Center

Selenium concentrations in Yuma Ridgway's Rails occupying managed and unmanaged emergent marshes at the Salton Sea

Yuma Ridgway's rail (Rallus obsoletus yumanensis, hereafter, "rail" are an endangered species for which patches of emergent marsh within the Salton Sea watershed comprise a substantial portion of habitat for the species' disjointed range in the southwestern United States. These areas of emergent marsh include: 1) marshes managed by federal (particularly the U.S. Fish and Wildlife Service's Sonny B
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Western Ecological Research Center (WERC)

Yuma Ridgway's Rail (Rallus obsoletus yumanensis) Population Surveys, Rail Movement, and Potential Habitat at the Salton Sea of California

Data were obtained as part of a project assessing risk to the federal and California listed endangered Yuma Ridgway's rail (Rallus obsoletus yumanensis) populations resulting from selenium contaminated agricultural runoff and to inform habitat restoration and management decisions. Four data sets were produced and used to analyze patterns of Yuma Ridgway's rail (Rallus obsoletus yumanensis, renamed
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Western Ecological Research Center (WERC)

Suisun Tidal Marsh Duck Use Dataset

Location data with corresponding habitat class (managed vs tidal marsh) and habitat type (permanent pond, seasonal pond, channel, or marshland) for waterfowl utilizing the Suisun Marsh region of California with species, sex, season and date information. These data support the following publication: Casazza, M.L., McDuie, F., Jones, S., Lorenz, A.A., Overton, C.T., Yee, J., Feldheim, C.L., Acke
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Western Ecological Research Center (WERC)

Migration stopover ecology of cinnamon teal in western North America

Identifying migration routes and fall stopover sites of cinnamon teal (Spatula cyanoptera septentrionalium) can provide a spatial guide to management and conservation efforts, and address vulnerabilities in wetland networks that support migratory waterbirds. Using high spatio-temporal resolution GSM-GPS transmitters, we tracked the fall migration of 61 cinnamon teal across western North America ov
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Western Ecological Research Center (WERC)

Waterfowl Disturbance in California and Nevada (2018)

Long-term environmental management to prevent waterfowl population declines is informed by ecology, movement behavior and habitat use patterns. Extrinsic factors such as human-induced disturbance can cause behavioral changes which may influence movement, and resource needs, driving variation that affects management efficacy. To better understand the relationship between human-based disturbance and
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Western Ecological Research Center (WERC)
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Movement behavior, habitat selection, and functional responses to habitat availability among four species of wintering waterfowl in California

Habitat selection analyses provide a window into the perceived value of habitats by animals and how those perceptions compare with other animals, change across time, or change in relation to availability (termed functional responses). Habitat selection analysis and functional responses can be used to develop strategies to avoid habitat limitations, guide habitat management, and set attainable cons
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Cory T. Overton, Michael L. Casazza
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Ecosystems Mission Area, Western Ecological Research Center (WERC)

AIMS for wildlife: Developing an automated interactive monitoring system to integrate real-time movement and environmental data for true adaptive management

To effectively manage species and habitats at multiple scales, population and land managers require rapid information on wildlife use of managed areas and responses to landscape conditions and management actions. GPS tracking studies of wildlife are particularly informative to species ecology, habitat use, and conservation. Combining GPS data with administrative data and a diverse suite of remotel
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Michael L. Casazza, Austen Lorenz, Cory T. Overton, Elliott L. Matchett, Andrea Lynn Mott, Desmond Alexander Mackell, Fiona McDuie
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Ecosystems Mission Area, Western Ecological Research Center (WERC)

Waterfowl recently infected with low pathogenic avian influenza exhibit reduced local movement and delayed migration

Understanding relationships between infection and wildlife movement patterns is important for predicting pathogen spread, especially for multispecies pathogens and those that can spread to humans and domestic animals, such as avian influenza viruses (AIVs). Although infection with low pathogenic AIVs is generally considered asymptomatic in wild birds, prior work has shown that influenza-infected b
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Claire S. Teitelbaum, Michael L. Casazza, Fiona McDuie, Susan E. W. De La Cruz, Cory T. Overton, Laurie Anne Hall, Elliott Matchett, Josh T. Ackerman, Jeffery D. Sullivan, Andrew M. Ramey, Diann Prosser
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Ecosystems Mission Area, Alaska Science Center, Eastern Ecological Science Center, Western Ecological Research Center (WERC)

Postbreeding movements and molting ecology of female gadwalls and mallards

The wing molt is an important annual life-history event that occurs in waterfowl and molt site selection can play an important role in determining survival. We tracked postbreeding movements of gadwall (Mareca strepera) and mallard (Anas platyrhynchos) females that bred in the Suisun Marsh (Suisun) of California, USA, to determine molt site selection and wing molt chronology. We attached backpack
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Jeffrey D Kohl, Michael L. Casazza, Cory T. Overton, Mark P. Herzog, Josh T. Ackerman, Cliff L. Feldheim, John M. Eadie
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Ecosystems Mission Area, Western Ecological Research Center (WERC)

Avian influenza antibody prevalence increases with mercury contamination in wild waterfowl

Environmental contamination is widespread and can negatively impact wildlife health. Some contaminants, including heavy metals, have immunosuppressive effects, but prior studies have rarely measured contamination and disease simultaneously, which limits our understanding of how contaminants and pathogens interact to influence wildlife health. Here, we measured mercury concentrations, influenza inf
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Claire Stewart Teitelbaum, Josh T. Ackerman, Mason A. Hill, Jaqueline M. Satter, Michael L. Casazza, Susan E. W. De La Cruz, Walter M. Boyce, Evan James Buck, John M. Eadie, Mark P. Herzog, Elliott Matchett, Cory T. Overton, Sarah H. Peterson, Magdalena Plancarte, Andrew M. Ramey, Jeffery D. Sullivan, Diann Prosser
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Ecosystems Mission Area, Eastern Ecological Science Center, Alaska Science Center, Western Ecological Research Center (WERC)

Yuma Ridgway’s rail selenium exposure and occupancy within managed and unmanaged emergent marshes at the Salton Sea

Yuma Ridgway’s rail (Rallus obsoletus yumanensis, hereafter, rail) is an endangered species for which patches of emergent marsh within the Salton Sea watershed comprise a substantial part of habitat for the species’ disjointed range in the southwestern United States. These areas of emergent marsh include (1) marshes managed by federal (particularly the U.S. Fish and Wildlife Service’s Sonny Bono S
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Mark A. Ricca, Cory T. Overton, Thomas W. Anderson, Angela Merritt, Eamon Harrity, Elliott Matchett, Michael L. Casazza
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Ecosystems Mission Area, Western Ecological Research Center (WERC)

Machine learned daily life history classification using low frequency tracking data and automated modelling pipelines: Application to North American waterfowl

BackgroundIdentifying animal behaviors, life history states, and movement patterns is a prerequisite for many animal behavior analyses and effective management of wildlife and habitats. Most approaches classify short-term movement patterns with high frequency location or accelerometry data. However, patterns reflecting life history across longer time scales can have greater relevance to species bi
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Cory T. Overton, Michael L. Casazza, Joseph Bretz, Fiona McDuie, Elliott Matchett, Desmond Alexander Mackell, Austen Lorenz, Andrea Mott, Mark P. Herzog, Josh T. Ackerman
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Ecosystems Mission Area, Western Ecological Research Center (WERC)

Pathways for avian influenza virus spread: GPS reveals wild waterfowl in commercial livestock facilities and connectivity with the natural wetland landscape

Zoonotic diseases are of considerable concern to the human population and viruses such as avian influenza (AIV) threaten food security, wildlife conservation and human health. Wild waterfowl and the natural wetlands they use are known AIV reservoirs, with birds capable of virus transmission to domestic poultry populations. While infection risk models have linked migration routes and AIV outbreaks,
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Fiona McDuie, Elliott Matchett, Diann Prosser, John Y. Takekawa, Maurice E. Pitesky, Austen Lorenz, Madeline M McCuen, Cory T. Overton, Josh T. Ackerman, Susan E. W. De La Cruz, Michael L. Casazza
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Ecosystems Mission Area, Western Ecological Research Center (WERC)

Megafires and thick smoke portend big problems for migratory birds

In 2020, the fire season affecting the western United States reached unprecedented levels. The 116 fires active in September consumed nearly 20,822 km2 (https://inciweb.nwcg.gov/accessible-view/ Accessed 2020-09-29) with eighty percent of this footprint (16,567 km2) from 68 fires occurring within California, Oregon, and Washington. Although the 2020 fire season was the most extreme on record, it e
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Cory T. Overton, Austen Lorenz, Eric P. James, Ravan Ahmadov, John M. Eadie, Fiona McDuie, Mark J. Petrie, Chris A. Nicolai, Melanie L. Weaver, Daniel A. Skalos, Shannon Skalos, Andrea Lynn Mott, Desmond Alexander Mackell, Anna Kennedy, Elliott Matchett, Michael L. Casazza
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Ecosystems Mission Area, Western Ecological Research Center (WERC)

Migration stopover ecology of Cinnamon Teal in western North America

Identifying migration routes and fall stopover sites of Cinnamon Teal (Spatula cyanoptera septentrionalium) can provide a spatial guide to management and conservation efforts, and address vulnerabilities in wetland networks that support migratory waterbirds. Using high spatiotemporal resolution GPS-GSM transmitters, we analyzed 61 fall migration tracks across western North America during our three
Authors
Desmond Alexander Mackell, Michael L. Casazza, Cory T. Overton, J. Patrick Donnelly, David Olson, Fiona McDuie, Josh T. Ackerman, John M. Eadie
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Ecosystems Mission Area, Western Ecological Research Center (WERC)

Informing wetland management with waterfowl movement and sanctuary use responses to human-induced disturbance

Long-term environmental management to prevent waterfowl population declines is informed by ecology, movement behavior and habitat use patterns. Extrinsic factors, such as human-induced disturbance, can cause behavioral changes which may influence movement and resource needs, driving variation that affects management efficacy. To better understand the relationship between human-based disturbance an
Authors
Fiona McDuie, Austen Lorenz, Robert C. Klinger, Cory T. Overton, Cliff L. Feldheim, Josh T. Ackerman, Michael L. Casazza
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Ecosystems Mission Area, Western Ecological Research Center (WERC)

Changes in the abundance and distribution of waterfowl wintering in the Central Valley of California, 1973–2000

The Central Valley of California is one of the most important areas for wintering waterfowl in the world and the focus of extensive conservation efforts to mitigate for historical losses and counter continuing stressors to habitats. To guide conservation, we analyzed trends in the abundance and distribution (spatiotemporal abundance patterns) of waterfowl and their habitats in the Central Valley a
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Joseph P. Fleskes, Michael L. Casazza, Cory T. Overton, Elliott Matchett, Julie L. Yee
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Ecosystems Mission Area, Western Ecological Research Center (WERC)
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Wildfire Smoke Disrupts Bird Migration in the West

SACRAMENTO, Calif. – Early fall wildfires in the western states and the smoke they generate pose a risk to birds migrating in the Pacific Flyway...

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