Quality Research Matters

CVJV Partners are always busy addressing unanswered questions, evaluating impacts, generating and analyzing new data to meet our high priority science needs to assure effective conservation delivery. 

Over the course of its history, the Central Valley Joint Venture has built a strong body of research to support the scientific recommendations and priorities reflected in the 2020 Implementation Plan. See below for a list of that research.

Conserving bird populations is a key goal for management of the Sacramento–San Joaquin Delta ecosystem and is likely to have effects well beyond its boundaries. To inform bird- conservation strategies, we identified Priority Bird Conservation Areas for riparian landbirds and waterbirds in the Delta, defined as the most valuable 5% of the landscape for each group. We synthesized data from 2,547 surveys for riparian landbirds and 7,820 surveys for waterbirds to develop predictive distribution models, which then informed spatial prioritization analyses. We identified a total of 26,019 ha that are a high priority for conserving riparian landbirds, waterbirds, or both, representing the most important places in the Delta to protect and manage, as well as strategic areas where adjacent restoration could expand valuable habitat. These Priority Bird Conservation Areas include the Yolo Bypass Wildlife Area, Cosumnes River Preserve, Stone Lakes National Wildlife Refuge, and bufferlands that surround the Sacramento County Regional Sanitation District. However, we also found that over 60% of the Priority Bird Conservation Areas are not currently protected, indicating a vulnerability to changes in land cover or land use. We recommend advancing strategies for bird conservation in the Delta by developing more specific objectives and priorities, extending these analyses to include other bird species, and planning to mitigate the loss of Priority Bird Conservation Areas where they are most vulnerable to land cover change. The predictive models and analysis framework we developed represent the current state of the science on areas important to bird conservation, while also providing a foundation for an evolving bird-conservation strategy that reflects the Delta’s continuously evolving knowledge base and landscape.

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Finding Connection opens a dialogue about addressing the Valley’s past trauma and engaging its current structural inequities from conservation and agroecological frameworks. Recent policy initiatives and legislation bolster its findings with optimism for achieving actual outcomes to affect the region’s difficult complex of problems.

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Meadow restoration and conservation have been a priority in the Sierra Nevada and southern Cascades of California for more than a decade, due to their ecological importance, rarity on the landscape, and highly degraded condition. To support collaborative efforts to conserve and restore these meadows, we integrated these meadows into the Central Valley Joint Venture’s conservation framework for the first time, adapting a general framework and a transparent, science-based approach to developing conservation objectives. We defined four planning regions, assessed the extent of meadow habitat available in each region, and for each of 10 focal bird species, we used recent bird survey data to estimate regional average breeding densities and population sizes. We estimated that 90% of the regional populations are small (<10,000) or very small (<1,000), and may be vulnerable to extirpation, and that Willow Flycatcher (Empidonax traillii), a California endangered species, is steeply declining. For each focal species in each region, we defined long-term (100-year) breeding density objectives and corresponding population size objectives that are intended to be feasible to achieve with extensive efforts to restore and enhance habitat quality in existing meadows, and we defined a long-term habitat quantity objective of no net loss of existing meadows. To provide a means by which progress toward the long-term conservation objectives can be measured, we also defined short-term (10-year) objectives that represent 10% of the improvement in breeding density and population size needed to reach the long-term objectives. We expect that protecting and restoring meadows to reach the conservation objectives defined here will improve the long-term viability and resilience of these focal species while also helping to restore the multiple benefits meadows provide to birds, other wildlife, and human communities within, nearby, and downstream of these rare and ecologically important meadows.

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A new term, Multiple-Benefit Conservation, has emerged in the conservation community, but has not been defined. We define Multiple-Benefit Conservation as conservation efforts designed to simultaneously benefit local communities of people, enhance ecological function, and improve habitat quality for fish and wildlife.

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The Yellow-billed Magpie (Pica nuttalli), a California endemic, declined substantially after the arrival of West Nile virus in the state in 2003 and has not recovered. The species primarily occupies oak woodlands and savannas, but some urban and suburban populations are sizable. Most research on the species’ ecology has been focused within the Central Coast region, and urban and suburban populations have received little attention. We provide information on population size, reproductive success, and nesting and foraging habitat use at sites in the Sacramento region, California, that support sizable breeding populations. We identified seven study areas based on high numbers reported in eBird or observed by us during 2017-2020. Site populations estimated in 2020 based on direct counts were generally lower than those from nest counts. Counts of recently fledged young in family groups yielded estimated reproductive rates similar to those observed on the Central Coast before arrival of West Nile virus, suggesting that the virus is not disproportionately affecting nestling survival. Sacramento magpies nested in the upper canopy of a wide variety of large native and non-native trees. Foraging occurred mainly in areas of irrigated turf and unirrigated annual grassland that was mowed or grazed. Analysis showed a strong relationship between the sizes of populations and amounts of low herbaceous foraging habitat within 0.5 and 1.5 km of colony sites and suggested a minimum of 6 and 48 ha of low foraging habitat is needed at these distances, respectively, to support nesting colonies. Absence of nesting colonies in many urban Sacramento parks, cemeteries, and schools with irrigated turf may be a result of inadequate area of foraging habitat or lack of mowed or grazed grassland. Our results provide habitat conservation and management guidance for the species.

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The Central Valley of California is the predominant wintering area for waterfowl and shorebirds in the Pacific Flyway. Using remote sensing data, researchers and habitat managers can track and quantify the effects of drought on availability of wetlands and other flooded waterfowl habitats. Bird locations from GPS marked waterfowl may be used to evaluate performance of remote sensing data for classifying habitats that are flooded and available for waterfowl. Importantly, high-resolution telemetry data recorded in near real-time can also provide information on how waterfowl respond to water management decisions intended to provide adequate habitat for wintering waterfowl. If availability of habitats to waterfowl is highly variable as a function of bird behavior (determined using telemetry), food resources may be insufficient to support target populations under conservation objectives. This research combines remote sensing data with high-resolution, near real-time waterfowl telemetry data to inform and optimize management of water supplies and habitats in the Central Valley of California.

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Harvested rice fields provide critical foraging habitat for wintering waterfowl in North America, but their value depends upon post-harvest treatments. We 
visited harvested ricefields in the Sacramento Valley, California, during the winters of 2007 and 2008 (recent period) and recorded their observed status as harvested (standing or mechanically modified stubble), burned, plowed, or flooded.

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To document and assess the success of their efforts on private lands, the CVJV and partners have initiated the Avian Monitoring on Private Lands (AMPL) project in collaboration with Point Blue Conservation Science. AMPL is a cooperative effort, involving the California Department of Fish and Game’s Landowner Incentive Program and California Waterfowl Habitat Program, the U.S. Fish and Wildlife Service’s Partners for Fish and Wildlife Program, the Natural Resource Conservation Service’s Wetlands Reserve Program, Point Blue Conservation Science, the Central Valley Joint Venture, and private landowners.

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The CVJV prepared this document to present a full range of Best Management Practice (BMP) options specific to managed wetlands. This technical guide was developed to provide information on habitat management strategies to reduce mosquito production in managed wetlands, and to facilitate greater cooperation among wetland habitat managers and Mosquito and Vector Control Districts (MVCDs). The BMPs identified in this guide are also an essential component of Integrated Pest Management (IPM) for mosquitoes, which incorporates knowledge of mosquito biology and the use of effective treatments to control mosquitoes while posing the least risk to people and the environment.

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Little is known about shorebird status in the Central Valley in summer, a period when wetland habitat reaches its annual nadir and for which wetland loss has been even greater than at other seasons. To fill this important data gap, the CVJV helped support Point Blue Conservation Science to coordinate counts of potentially breeding shorebirds at wetlands and other shallow-water habitats throughout the Central Valley in June 2003. Multiple federal, state, academic, and private partners were involved in the surveys.

In a final report submitted to the CVJV and in a paper currently being reviewed for publication, Point Blue Conservation Science reports the patterns of geographic distribution, abundance, and broadscale habitat use of the Black-necked Stilt and American Avocet, the shorebird species most representative of these habitats in the Central Valley. Point Blue Conservation Science also identifies threats to nesting shorebirds and makes recommendations for management and research needed to ensure the effective conservation of their populations and habitat in this region.

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Evaluating Moist-Soil Seed Production and Management in Central Valley Wetlands to Determine Habitat Needs for Waterfowl (1) evaluates the amount of food available in Central Valley wetlands; (2) investigates the influence of wetland management on seed production in wetlands; and (3) develops a new technique for monitoring wetland seed production.

In a final report submitted to the CVJV and in a paper currently being reviewed for publication, Point Blue Conservation Science reports the patterns of geographic distribution, abundance, and broadscale habitat use of the Black-necked Stilt and American Avocet, the shorebird species most representative of these habitats in the Central Valley. Point Blue Conservation Science also identifies threats to nesting shorebirds and makes recommendations for management and research needed to ensure the effective conservation of their populations and habitat in this region.

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Avian Disease in the Central Valley of California examines trends in avian botulism and avian cholera exploring potential relationships between recent habitat restoration efforts within the valley and waterfowl disease mortality.

AVIAN DISEASE IN THE CENTRAL VALLEY OF CALIFORNIA: (centralvalleyjointventure.org)

Hunting success is important to the Joint Venture’s wetland conservation programs, and the hunting public needs to be kept informed about factors that control the availability of waterfowl and hunter success. In response to changes in hunting regulations and a resulting dissatisfaction with hunting success during the 1995-96 hunting season, the Joint Venture Technical Committee assessed hunter success during that time compared to recent years and provided explanations for documented differences and similarities. They concluded that total harvest and hunter success in 1995-96, did not differ enough from recent trends to warrant major changes in habitat or harvest management at that time.

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The Pacific Flyway Project was the first ever attempt to establish baseline data on the abundance and distribution of shorebirds in wetland habitats along the Pacific Flyway from Alaska to Baja California. Data from the Pacific Flyway Project provide information critical to current shorebird conservation planning decisions, including the management of wetlands in the Central Valley.

Surveys of California’s Central Valley between 1992-1995 document it as one of the most important regions in western North America to migratory and wintering shorebirds. Development of a sound conservation strategy is crucial for the preservation of shorebird populations in the Central Valley, as this agriculturally-dominated landscape is among the most altered in North America and remains vulnerable to strong economic and population growth pressures that may impact shorebird habitats in the future.

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For the past 25 years, CVJV Management Board member PG&E has led various bird protection efforts. They work collaboratively with organizations such as the U.S. Fish and Wildlife Service to minimize the dangers that transmission lines and other electrical equipment pose to birds. PG&E’s Avian Protection Plan seeks to protect migratory, threatened and endangered birds from these risks.

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The US Geological Survey, in partnership with the CVJV, has supported and benefited from extensive research including the following projects. For more information about individual researchers and their projects

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Northeastern California (SONEC) Southern Oregon-Northeastern California (SONEC) provides critical spring staging habitat for northern pintails and other waterfowl in the Pacific Flyway. This multi-phased project used a variety of methods to: Measure timing, distribution, and magnitude of use by pintails and other waterfowl; Identify important spring habitats and quantify day and night use by pintails; Map dynamics and distribution of waterbird spring habitat in SONEC; Determine waterfowl food habits in spring-flooded pasture and hayfields; Quantify density of waterbird foods in spring-flooded pasture and hayfields, and; Determine the body condition of waterfowl migrating through SONEC in spring.

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