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Cory Overton

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

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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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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, 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.
Learn More
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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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Marsh with tall grasses and orange markers set out by scientists

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
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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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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. F
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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)

Locations of Pacific Flyway Ducks in and near Commercial Livestock Facilities of the Western USA (2015-2021)

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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Western Ecological Research Center (WERC)

Tule Greater White-fronted Goose Migration Tracks (2019-2020) and Atmospheric Smoke Concentrations (2020).

April through May (spring) and August through September (fall) locations for tule greater white-fronted geese (Anser albifrons elgasi) marked with GPS collars at Summer Lake Wildlife Area, OR in 2018 and 2019. Locations may include pre-migration and post-migration designations. Locations occurring between September 11, 2020, and arrival at, or within 50 kilometers of the Summer Lake Wildlife Area
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Western Ecological Research Center (WERC)

Comparisons of Gambel's quail survey methods conducted in 2016 within the Mohave Desert of California with results and summaries

Data includes results collected in the Mohave Desert during 2016 using three survey methods (acoustic recording units, camera traps, and call-count surveys) to detect gamebirds, primarily Gambel's quail (Callipepla gambelii) but also including records of mourning dove (Zenaida macroura), Eurasian collared-dove (Streptopelia decaocto), and chukar (Alectoris chukar). ARU data includes the Selections
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Western Ecological Research Center (WERC)

Classification of Waterfowl Habitat, and Quantification of Interannual Space Use and Movement Distance from Primary Roosts to Night Feeding Locations by Waterfowl in California for October - March of 2015 through 2018

Technological advancements in Global Positioning System (GPS) telemetry markers allow almost real-time observation of waterfowl movements and habitat selection. Telemetry data on ducks marked with GPS transmitters can be used to evaluate performance of remote sensing data (for example, dynamic open-water maps produced by Point Blue Conservation Science) for classifying habitats that are flooded an
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Western Ecological Research Center (WERC)

Integrating Spatially Explicit Indices of Abundance and Habitat Quality: An Applied Example for Greater Sage-grouse Management

This study provides timely and highly useful information about greater sage-grouse over a large area of the Great Basin. USGS researchers and their colleagues created a template for combining landscape-scale occurrence or abundance data with habitat selection data in order to identify areas most critical to sustaining populations of species of conservation concern. The template also identifies tho
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Western Ecological Research Center (WERC)
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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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Ecosystems, 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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Ecosystems, 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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Ecosystems, 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
By
Ecosystems, 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
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Ecosystems, 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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Ecosystems, Western Ecological Research Center (WERC)

Interrupted incubation: How dabbling ducks respond when flushed from the nest

Nesting birds must provide a thermal environment sufficient for egg development while also meeting self‐maintenance needs. Many birds, particularly those with uniparental incubation, achieve this balance through periodic incubation recesses, during which foraging and other self‐maintenance activities can occur. However, incubating birds may experience disturbances such as predator or human activit
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Ecosystems, Western Ecological Research Center (WERC)

Using high resolution satellite and telemetry data to track flooded habitats, their use by waterfowl, and evaluate effects of drought on waterfowl and shorebird bioenergetics in California

Wetland managers in the Central Valley of California, a dynamic hydrological landscape, require information regarding the amount and location of existing wetland habitat to make decisions on how to best use water resources to support multiple wildlife objectives, particularly during drought. Scientists from the U.S. Geological Survey Western Ecological Research Center (WERC), Point Blue Conservati
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Ecosystems, Western Ecological Research Center (WERC)

Waterfowl use of wetland habitats informs wetland restoration designs for multi‐species benefits

Extensive global estuarine wetland losses have prompted intensive focus on restoration of these habitats. In California, substantial tracts of freshwater, brackish and tidal wetlands have been lost. Given the anthropogenic footprint of development and urbanization in this region, wetland restoration must rely on conversion of existing habitat types rather than adding new wetlands. These restoratio
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Ecosystems, Western Ecological Research Center (WERC)

Ecological insights from three decades of animal movement tracking across a changing Arctic

The Arctic is entering a new ecological state, with alarming consequences for humanity. Animal-borne sensors offer a window into these changes. Although substantial animal tracking data from the Arctic and subarctic exist, most are difficult to discover and access. Here, we present the new Arctic Animal Movement Archive (AAMA), a growing collection of more than 200 standardized terrestrial and mar
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Ecosystems, Western Ecological Research Center (WERC)

Gambel’s quail survey variability and implications for survey design in the Mohave Desert

Careful design of a wildlife population monitoring strategy is necessary to obtain accurate and precise results whether the purpose of the survey is development of habitat suitability models, to estimate abundance, or assess site occupancy. Important characteristics to consider in survey design are sources of elevated variability, particularly within‐subject variability, which increases the amount
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Ecosystems, Western Ecological Research Center (WERC)

Good prospects: High-resolution telemetry data suggests novel brood-site selection behavior in waterfowl

Breeding success should increase with prior knowledge of the surrounding environment, which is dependent upon an animal’s ability to evaluate habitat. Prospecting for nesting locations and migratory stop-over sites are well-established behaviors among bird species. We assessed whether ducks in Suisun Marsh, California, USA, a brackish marsh, prospect for suitable wetlands in the week prior to broo
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Ecosystems, 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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