Geology topics

Joseph P. Fleskes

Publications and source records attributed to Joseph P. Fleskes.

At least 19 recordsLinked to original sources

USGS2024

Body mass changes of dabbling and diving ducks wintering in California

Bird body mass is often used as an index of body condition and fluctuates throughout the year in response to environmental conditions and avian life-history events. We examined the body mass of 59,572 ducks representing 13 species (7 dabbling duck species and 6 diving duck species) harvested within the 3 regions of the Central Valley in California, USA (Sacramento Valley, Suisun Marsh, San Joaquin Valley). Data collection occurred in winter during 5 hunting seasons (2014–2015, 2015–2016, 2017–2018, 2018–2019, 2019–2020). For all species, age, and sex classes, the body mass of dabbling ducks varied temporally and was lowest at the end of the hunting season in late January, declining from the beginning of the hunting season in mid-October (northern pintail [ Anas acuta ]: −11.4% to −20.4%; northern shoveler [ Spatula clypeata ]: −3.5% to −17.3%; cinnamon teal [ Anas cyanoptera ]: −5.0% to −17.1%; American wigeon [ Mareca americana ]: −6.9% to −12.2%; American green-winged teal [ Anas carolinensis ]: −5.9% to −11.9%; mallard [ Anas platyrhynchos ]: −1.8% to −9.6%; gadwall [ Mareca strepera ]: −2.2% to −8.4%). As expected, adults (after hatch-year) were heavier than immature (hatch-year) birds (within males: 0.6–8.6%; within females: 0.1–6.6%) and males were heavier than females (within adults: 3.1–38.6%; within immatures: 5.4–33.5%) at the end of the hunting season in all species. Within dabbling duck species, body masses did not differ among regions at the beginning of the hunting season but were heavier in the Sacramento Valley (0.5–14.4%) than other areas by the end of the hunting season. In contrast, body masses of diving ducks did not vary substantially during the hunting season or among regions. Diving ducks demonstrated inconsistent changes in mass from the beginning to the end of the season (lesser scaup [ Aythya affinis ]: 3.4% to 12.3%; canvasback [ Aythya valisineria ]: 5.1% to 6.1%; bufflehead [ Bucephala albeola ]: −3.2% to 1.6%; ring-necked duck [ Aythya collaris ]: −4.9% to 2.6%; common goldeneye [ Bucephala clangula ]: −3.2% to −2.4%; ruddy duck [ Oxyura jamaicensis ]: −16.5% to 5.5%). The substantial temporal and spatial differences in dabbling duck body masses suggest that habitat quality (as measured by caloric value of the available food) or quantity may decline during winter and varies regionally within California's Central Valley.

California↗

USGS2021

Assessment of cereal grain waste densities to aid waterfowl conservation planning in the Klamath Basin

Postharvest waste seed from cereal grains is a major dietary component of waterfowl in the Klamath Basin in northeastern California and southeastern Oregon, a region that plays host to over a million waterfowl annually. Understanding food abundance is critical to local waterfowl management; therefore, we conducted a study in 2008 to investigate waste grain densities in barley, oat, and wheat fields. We used hierarchal mixed effect models to assess several factors that may affect waste grain densities postharvest. We also compared the effects of residue management practices to measure the effect of these treatments. To understand the scope of postharvest practices, we conducted a weekly road survey to document treatments applied to fields in our study area. We found that region best explained the variance of postharvest waste grain in barley fields, where the Tule Lake region had 89% greater densities than Lower Klamath. Neither harvester age nor baling affected waste grain in oats fields. In wheat fields, the model containing region and lodging ranked highest, where the Tule Lake region had 66% greater waste densities than Lower Klamath, and lodging increased waste grain by 70%. Burning did not reduce waste grain in barley or oat fields. Chisel-disking reduced waste grain by 94% in wheat fields compared with postharvest. Our field treatment survey found that 70% of barley fields were untreated while 18% were disked and 13% were burned and flooded. We estimated that 82% of oat fields were burned postharvest, while 18% were burned and flooded. In wheat, 61% of fields were left untreated, while 16% were disked, 8% were chisel-plowed, and 7% were flooded postharvest. Flooding and burning occurred primarily on National Wildlife Refuges, while disking, chisel-plowing, and postharvest irrigation occurred solely on private properties. Our results indicate that reducing tillage treatments would boost accessibility of cereal grain food resources to waterfowl in the Klamath Basin, and incentives to flood grain fields on private properties should be considered for the same purpose when and where possible.

California, Oregon↗

USGS2021

Body condition of wintering Pacific greater white-fronted geese

Extreme changes to key waterfowl habitats in the Klamath Basin (KB) on the Oregon–California border and the Sacramento Valley (SV) in California, USA, have occurred since 1980. The spatial distribution of Pacific greater white‐fronted geese ( Anser albifrons sponsa ; geese) has likewise changed among these areas and population size has grown from 79,000 to >600,000 geese during the same period. To assess the effects of landscape changes and spatial‐temporal distribution of geese, we collected Pacific greater white‐fronted geese during winters of 2009–2010 and 2010–2011 in the KB and SV and compared their body condition to geese collected during 1979–1980 and 1980–1981. We modeled body and lipid mass to assess body condition for each sex independently and examined the influence of collection day, year, and region. Body condition of geese varied throughout the winter and within years in a nonlinear fashion. We detected an increase in body condition in both sexes during December and January in the SV, which corresponds with improved habitat conditions and increases seen in other species in the region. Body condition upon arrival in fall migration varied by year for females and by year and region for males. Males and females arrived in poorer body condition during 2010–2011 than all other study years and males in the KB during 2010–2011 had extremely low lipid mass, reflecting poor regional habitat conditions induced by drought. Body condition of females varied over spring, by year, and by region and regional effects were evident for males. Body condition was significantly higher for geese in the SV than in the KB during spring. Our results suggest that Pacific greater white‐fronted geese have adapted to a changing landscape and have adjusted historical spatial use patterns to take advantage of more favorable conditions in the SV between 1979 and 2010.

California, Oregon↗

USGS2020

Linking nest microhabitat selection to nest survival within declining pheasant populations in the Central Valley of California

Context: The ring-necked pheasant ( Phasianus colchicus ) has experienced considerable population declines in recent decades, especially in agricultural environments of the Central Valley of California. Although large-scale changes in land cover have been reported as an important driver of population dynamics, the effects of microhabitat conditions on specific demographic rates (e.g. nesting) are largely unknown. Aims: Our goal was to identify the key microhabitat factors that contribute to wild pheasant fitness by linking individual-level selection of each microhabitat characteristic to the survival of their nests within the California Central Valley. Methods: We radio- or GPS-marked 190 female ring-necked pheasants within five study areas and measured nest-site characteristics and nest fates during 2013–2017. Specifically, we modeled microhabitat selection using vegetation covariates measured at nest sites and random sites and then modeled nest survival as a function of selecting each microhabitat characteristic. Key results: Female pheasants tended to select nest sites with greater proportions of herbaceous cover and avoided areas with greater proportions of bare-ground. Specifically, perennial grass cover was the most explanatory factor with regard to nest survival, but selection for increasing visual obstruction alone was not shown to have a significant effect on survival. Further, we found strong evidence that pheasants selecting sites with greater perennial grass height were more likely to have successful nests. Conclusions: Although pheasants will select many types of vegetation available as cover, our models provided evidence that perennial grasses are more beneficial than other cover types to pheasants selecting nesting sites. Implications: Focusing management actions on promoting perennial grass cover and increased heights at the microsite level, in lieu of other vegetative modifications, may provide improved quality of habitat for nesting pheasants and, perhaps, result in increased productivity. This is especially important if cover is limited during specific times of the nesting period. Understanding how microhabitat selection influences fitness can help land managers develop strategies to increase the sustainability of hunted populations of this popular game-bird species.

California↗

USGS2019

Monitoring breeding and survival of ring-necked pheasant (Phasianus colchicus) in the Sacramento Valley, Sacramento-San Joaquin River Delta, and Klamath Basin, northern California—Five-year summary, 2013–17

The U.S. Geological Survey Western Ecological Research Center, Pheasants Forever, Mandeville Island Duck Club, and the California Department of Fish and Wildlife collaborated in a reconnaissance study to monitor populations of ring-necked pheasant ( Phasianus colchicus ) using radio-telemetry in the Sacramento Valley, Sacramento-San Joaquin River Delta, and Klamath Basin of northern California. The purpose of this study was to provide agencies and private landowners with a framework of decision-support tools to help manage pheasant populations in California. During winter, spring, and autumn of 2013–17, we radio- or Global Positioning System-marked 227 female pheasant across six study sites. Data collection was focused on investigating nest-site and brood-rearing habitat selection, examining avian predator composition, and estimating population vital rates to improve our understanding of pheasant population dynamics and to identify factors that may contribute to decreases in pheasant populations in California. The cumulative annual adult survival probability across all sites during 2013–17 was 27.6 percent (95-percent confidence interval [CI], 21.9–33.6), and the cumulative nest and brood survival probabilities were 34.5 percent (95-percent CI, 27.0–42.2) and 54.2 percent (95-percent CI, 43.7–63.5), respectively. Evidence from microhabitat surveys completed at nest-sites, brood locations, and random locations suggested that marked female pheasant tended to select increasing vertical cover and residual vegetation cover and tended to avoid areas of increasing bare ground cover regardless of life-history stage. However, females at nest-sites selected increasing grass cover and height, whereas brood-rearing females tended to select increasing forb cover and height. Only perennial grass cover and perennial grass height were shown to have a positive influence on nest survival, which suggests that increasing perennial grass cover in areas occupied by pheasant may increase nest survival. Analysis of environmental factors linked to vital rate information are ongoing and will continue with investigations at increased spatial scales (that is, macro-habitat) to develop integrated population models that can incorporate abundance estimates from crow count data with vital rates from telemetry data. This report includes results from 5 years of data collection and should be interpreted with caution, as these findings are preliminary.

California↗

USGS2019

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 2.3.4.4 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 (LP) and HP IAVs to refine inference on the spatiotemporal extent of HP genome constellations and to evaluate possible evolutionary pathways. We screened samples from 1496 waterfowl and 1142 marine mammals collected from April 2014 to August 2015 and detected IAV RNA in 159 samples collected from birds ( n = 157) and pinnipeds ( n = 2). HP IAV RNA was identified in three samples originating from American wigeon ( Anas americana ). Genetic sequence data were generated for a clade 2.3.4.4 HP IAV-positive diagnostic sample and 57 LP IAV isolates. Phylogenetic analyses revealed that the HP IAV was a reassortant H5N8 virus with gene segments closely related to LP IAVs detected in mallards ( Anas platyrhynchos ) sampled in California and other IAVs detected in wild birds sampled within the Pacific Americas Flyway. In addition, our analysis provided support for common ancestry between LP IAVs recovered from waterfowl sampled in California and gene segments of reassortant HP H5N1 IAVs detected in British Columbia, Canada and Washington, USA. Our investigation provides evidence that waterfowl are likely to have played a role in the evolution of reassortant HP IAVs in the Pacific Americas Flyway during 2014–2015, whereas we did not find support for spill-over infections in potential pinniped hosts.

Emerging Microbes & Infections↗

USGS2018

Waterbird habitat in California's Central Valley basins under climate, urbanization, and water management scenarios

California's Central Valley provides critical, but threatened habitat and food resources for migrating and wintering waterfowl, shorebirds, and other waterbirds. The Central Valley is comprised of nine basins that were defined by the Central Valley Joint Venture (CVJV) to assist in conservation planning. Basins vary in composition and extent of habitats, which primarily include croplands and wetlands that rely on water supplies shared with other competing human and environmental uses. Changes in climate, urban development, and water supply management are uncertain and could reduce future availability of water supplies supporting waterbird habitats and limit effectiveness of wetland restoration planned by the CVJV to support wintering waterbirds. We modeled 17 plausible scenarios including combinations of three climate projections, three urbanization rates, and five water supply management options to promote agricultural and urban water uses, with and without wetland restoration. Our research examines the reduction in quantity and quality of habitats during the fall migration-wintering period by basin under each scenario, and the efficacy of planned wetland restoration to compensate reductions in flooded areas of wetland habitats. Scenario combinations of projected climate, urbanization, and water supply management options reduced availability of flooded cropland and wetland habitats during fall-winter and degraded the quality of seasonal wetlands (i.e., summer-irrigation for improved forage production), though the extent and frequency of impacts varied by basin. Planned wetland restoration may substantially compensate for scenario-related effects on wetland habitats in each basin. However, results indicate that Colusa, Butte, Sutter, San Joaquin, and Tulare Basins may require additional conservation to support summer-irrigation of seasonal wetlands and winter-flooding of cropland habitats. Still further conservation may be required to provide sufficient areas of flooded seasonal and semi-permanent wetlands in San Joaquin and Tulare Basins during fall-winter. The main objective of this research is to provide decision-support for achieving waterbird conservation goals in the valley and to inform CVJV's regional conservation planning.

California↗

USGS2018

California mallards: a review

Mallards (Anas platyrhynchos) are the most abundant breeding waterfowl species in California and are important to waterfowl hunters in the state. California is unique among major North American wintering waterfowl areas, in that most mallards harvested in California are also produced in California, meaning that California must provide both high quality wintering and breeding habitats for mallard populations to remain stable. California’s breeding and wintering mallard population estimates have generally declined since the mid-1990s. Herein, we synthesized existing information on the ecology of breeding mallards in California and summarize key demographic rates. In general, demographic estimates differed substantially from other mallard populations in North America, highlighting the importance of separate management of western mallard populations. We suggest long-term research and monitoring activities to help improve management.

California Fish and Game↗

USGS2017

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 and its major subregions (Sacramento Valley, Suisun Marsh, Delta, San Joaquin Valley), from 1973 through 2000. We used existing databases, satellite imagery, and aerial photography to measure habitat area, and aerial surveys and radio telemetry to track the abundance and distribution of wintering waterfowl. Wetlands increased throughout the Central Valley, but agricultural fields flooded after harvest increased greatly to the north in the Sacramento Valley and decreased to the south in the San Joaquin Valley, resulting in an overall increase in the relative availability of winter habitat in the former region. Reflecting the continental decline of the most abundant wintering species (Northern Pintail, Anas acuta ), the overall abundance of wintering waterfowl in the Central Valley declined during our study. By contrast, numbers of the American Wigeon ( A. americana ), Mallard ( A. platyrhynchos ), and Northern Shoveler ( A. clypeata ) were stable, and numbers of the Green-winged Teal ( A. crecca ), Gadwall ( A. strepera ), diving ducks, and geese increased from 1973–1982 to 1998–2000. The areas of greatest abundance of wintering waterfowl within the Central Valley shifted northward as many species responded to changes in the distribution of habitats. Wintering waterfowl migrated earlier in fall and winter from the San Joaquin Valley, Suisun Marsh, and Delta to the Sacramento Valley, and fewer waterfowl emigrated from the Sacramento Valley to other parts of the Central Valley. Because changes in waterfowl distribution were primarily a response to the increase of a beneficial agricultural practice (i.e., the flooding of rice after harvest) in the Sacramento Valley, changing agro-economics, reduction of water supplies, or other factors that reduce this practice could change the abundance and distribution of wintering waterfowl in the Central Valley rapidly. Thus to maintain abundant suitable habitat and restore the historical distribution of wintering waterfowl, our results suggest a continuing need for the conservation of wetlands and other waterfowl habitats with secure water supplies throughout the Central Valley. Despite our findings, achieving goals for winter waterfowl populations in the Central Valley likely will depend on a combination of factors including some acting in breeding ranges farther north or elsewhere outside of the valley.

California↗

USGS2017

Long-term and widespread changes in agricultural practices influence ring-necked pheasant abundance in California

Declines in bird populations in agricultural regions of North America and Europe have been attributed to agricultural industrialization, increases in use of agrochemical application, and increased predation related to habitat modification. Based on count data compiled from Breeding Bird Survey (BBS) from 1974 to 2012, Christmas Bird Count (CBC) collected from 1914 to 2013, and hunter data from Annual Game Take Survey (AGTS) for years 1948–2010, ring-necked pheasants ( Phasianus colchicus ) in California have experienced substantial declines in agricultural environments. Using a modeling approach that integrates all three forms of survey data into a joint response abundance index, we found pheasant abundance was related to the amount of harvested and unharvested crop land, types of crops produced, amount of total pesticide applied, minimum temperature, precipitation, and numbers of avian competitors and predators. Specifically, major changes in agricultural practices over the last three decades were associated with declines in pheasant numbers and likely reflected widespread loss of habitat. For example, increases in cropland were associated with increased pheasant abundance during early years of study but this effect decreased through time, such that no association in recent years was evidenced. A post hoc analysis revealed that crops beneficial to pheasant abundance (e.g., barley) have declined substantially in recent decades and were replaced by less advantageous crops (e.g., nut trees). An additional analysis using a restricted data set (1990–2013) indicated recent negative impacts on pheasant numbers associated with land use practices were also associated with relatively high levels of pesticide application. Our results may provide valuable information for management policies aimed at reducing widespread declines in pheasant populations in California and may be applicable to other avian species within agricultural settings. Furthermore, this general analytical approach is not limited to pheasants and could be applied to other taxa for which multiple survey data sources exist.

California↗

USGS2017

Body mass, wing length, and condition of wintering ducks relative to hematozoa infection

Waterfowl managers lack information regarding factors that may be reducing the positive response of waterfowl body condition to habitat improvements. Protozoan blood parasites (i.e., hematozoa) are commonly found in birds and have been related to reduced body mass, wing length, and body condition. We studied relationships between 12 measures of hematozoa infection and body mass, wing length, and body mass divided by wing length (i.e., body condition index [BCI]) of the five most common duck species (northern pintail [ Anas acuta ], mallard [ A. platyrhynchos ], green-winged teal [ A. crecca ], American wigeon [ A. Americana ], northern shoveler [ A. clypeata ]) wintering in the Central Valley of California during October 2006-January 2007. After accounting for variation due to species, age-sex cohort, Central Valley region, and month; wing length, body mass, and BCI were found to be negatively related to infection by Leucocytozoon and by "any hematozoa" but not related to infection by only Plasmodium or Haemoproteus , or coinfections of greater than one genera or parasite haplotype (albeit, few ducks had Plasmodium or Haemoproteus infection or coinfections). Evidence of a negative relationship with infection was stronger for body mass and BCI than for wing length and indicated that the relationships varied among species, age-sex cohorts, regions, and months. Compared to uninfected ducks, hematozoa-infected duck body mass, wing length, and BCI was -1.63% (85% CI = -2.79%- -0.47%), -0.12% (-0.41%- +0.17%), and -1.38% (-2.49%- -0.26%), respectively. Although, seemingly small, the -1.63% difference in body mass represents a large percentage (e.g., 38% for northern pintail) of the observed increase in wintering duck body mass associated with Central Valley habitat improvements. Because infection prevalence and relationship to body condition might change over time due to climate or other factors, tracking hematozoa infection prevalence might be important to inform and accurately assess the effect of conservation programs designed to improve waterfowl body condition.

California↗

USGS2017

Projected impacts of climate, urbanization, water management, and wetland restoration on waterbird habitat in California’s Central Valley

The Central Valley of California is one of the most important regions for wintering waterbirds in North America despite extensive anthropogenic landscape modification and decline of historical wetlands there. Like many other mediterranean-climate ecosystems across the globe, the Central Valley has been subject to a burgeoning human population and expansion and intensification of agricultural and urban development that have impacted wildlife habitats. Future effects of urban development, changes in water supply management, and precipitation and air temperature related to global climate change on area of waterbird habitat in the Central Valley are uncertain, yet potentially substantial. Therefore, we modeled area of waterbird habitats for 17 climate, urbanization, water supply management, and wetland restoration scenarios for years 2006–2099 using a water resources and scenario modeling framework. Planned wetland restoration largely compensated for adverse effects of climate, urbanization, and water supply management changes on habitat areas through 2065, but fell short thereafter for all except one scenario. Projected habitat reductions due to climate models were more frequent and greater than under the recent historical climate and their magnitude increased through time. After 2065, area of waterbird habitat in all scenarios that included severe warmer, drier climate was projected to be >15% less than in the “existing” landscape most years. The greatest reduction in waterbird habitat occurred in scenarios that combined warmer, drier climate and plausible water supply management options affecting priority and delivery of water available for waterbird habitats. This scenario modeling addresses the complexity and uncertainties in the Central Valley landscape, use and management of related water supplies, and climate to inform waterbird habitat conservation and other resource management planning. Results indicate that increased wetland restoration and additional conservation and climate change adaptation strategies may be warranted to maintain habitat adequate to support waterbirds in the Central Valley.

California↗

USGS2017

Mallard (Anas platyrhynchos) mortality and recovery rates vary by wing molt status at time of banding

Recovery (i.e., shot, retrieved, and reported) rates and daily mortality risk of 52,330 adult Mallards ( Anas platyrhynchos ) leg-banded during pre-molt, in-molt, or post-molt during 1985–2011 were evaluated to better understand mortality during wing molt in dynamics of the Mallard population in California, USA. Recovery rates and non-hunting mortality risk varied by molt status at time of banding and California region where banded. Mallards banded during post-molt were 1.22 (95% credible interval = 1.10–1.32) times more likely to be recovered than Mallards banded pre-molt; recovery probability was similar for pre-molt and in-molt Mallards. Mallards banded post-molt had 0.43 (0.17–0.98) and in-molt 0.87 (0.51–1.49) times the daily risk of non-hunting mortality as Mallards banded pre-molt. Mallards were 0.92 (0.86–0.98) times as likely to be recovered, and daily risk of non-hunting mortality was 2.93 (1.79–4.94) times greater, if banded in Northeastern California than in California's Central Valley. Results indicate that high mortality during the molt period, especially in Northeastern California where most Mallards that breed in California molt, might be negatively affecting recovery (and potentially annual survival) of Mallards in California. Thus, conservation programs that reduce mortality during molt could help attain the desired population size for Mallards nesting in California.

Waterbirds↗

USGS2017

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 mitigate disease transmission to food animals. The highly pathogenic avian influenza (HPAI) virus represents a significant risk to the poultry industry. The Central Valley of California offers a unique geographical confluence of commercial poultry and wild waterfowl, which are thought to be a key reservoir of avian influenza (AI). Therefore, understanding spatio-temporal distributions of waterfowl could improve our understanding of potential risk of HPAI exposure from a commercial poultry perspective. Using existing radio-telemetry data on waterfowl (U.S. Geological Survey) in combination with habitat and vegetation data based on Geographic Information Systems (GIS), we are developing GIS-based statistical models that predict the probability of waterfowl presence (Habitat Suitability Mapping). Near-real-time application can be developed using recent habitat data derived from Landsat imagery (acquired by satellites and publicly available through the U.S. Geological Survey) to predict temporally- and spatially-varying distributions of waterfowl in the Central Valley. These results could be used to provide decision support for the poultry industry in addressing potential risk of HPAI exposure related to waterfowl proximity.

California↗

USGS2016

Potential effects of drought on carrying capacity for wintering waterfowl in the Central Valley of California

We used the bioenergetics model TRUEMET to evaluate potential effects of California's recent drought on food supplies for waterfowl wintering in the Central Valley under a range of habitat and waterfowl population scenarios. In nondrought years in the current Central Valley landscape, food supplies are projected to be adequate for waterfowl from fall through early spring (except late March) even if waterfowl populations reach North American Waterfowl Management Plan goals. However, in all drought scenarios that we evaluated, food supplies were projected to be exhausted for ducks by mid- to late winter and by late winter or early spring for geese. For ducks, these results were strongly related to projected declines in winter-flooded rice fields that provide 45% of all the food energy available to ducks in the Central Valley in nondrought water years. Delayed flooding of some managed wetlands may help alleviate food shortages by providing wetland food resources better timed with waterfowl migration and abundance patterns in the Central Valley, as well as reducing the amount of water needed to manage these habitats. However, future research is needed to evaluate the impacts of delayed flooding on waterfowl hunting, and whether California's existing water delivery system would make delayed flooding feasible. Securing adequate water supplies for waterfowl and other wetland-dependent birds is among the greatest challenges facing resource managers in coming years, especially in the increasingly arid western United States.

Journal of Fish and Wildlife Management↗

USGS2016

U.S. Geological Survey science strategy for highly pathogenic avian influenza in wildlife and the environment (2016–2020)

Introduction Through the Science Strategy for Highly Pathogenic Avian Influenza (HPAI) in Wildlife and the Environment, the USGS will assess avian influenza (AI) dynamics in an ecological context to inform decisions made by resource managers and policymakers from the local to national level. Through collection of unbiased scientific information on the ecology of AI viruses and wildlife hosts in a changing world, the U.S. Geological Survey (USGS) will enhance the development of AI forecasting tools and ensure this information is integrated with a quality decision process for managing HPAI. The overall goal of this USGS Science Strategy for HPAI in Wildlife and the Environment goes beyond documenting the occurrence and distribution of AI viruses in wild birds. The USGS aims to understand the epidemiological processes and environmental factors that influence HPAI distribution and describe the mechanisms of transmission between wild birds and poultry. USGS scientists developed a conceptual model describing the process linking HPAI dispersal in wild waterfowl to the outbreaks in poultry. This strategy focuses on five long-term science goals, which include: Science Goal 1—Augment the National HPAI Surveillance Plan; Science Goal 2—Determine mechanisms of HPAI disease spread in wildlife and the environment; Science Goal 3—Characterize HPAI viruses circulating in wildlife; Science Goal 4—Understand implications of avian ecology on HPAI spread; and Science Goal 5—Develop HPAI forecasting and decision-making tools. These goals will help define and describe the processes outlined in the conceptual model with the ultimate goal of facilitating biosecurity and minimizing transfer of diseases across the wildlife-poultry interface. The first four science goals are focused on scientific discovery and the fifth goal is application-based. Decision analyses in the fifth goal will guide prioritization of proposed actions in the first four goals.

Open-File Report↗

USGS2016

Increased body mass of ducks wintering in California's Central Valley

Waterfowl managers lack the information needed to fully evaluate the biological effects of their habitat conservation programs. We studied body condition of dabbling ducks shot by hunters at public hunting areas throughout the Central Valley of California during 2006–2008 compared with condition of ducks from 1979 to 1993. These time periods coincide with habitat increases due to Central Valley Joint Venture conservation programs and changing agricultural practices; we modeled to ascertain whether body condition differed among waterfowl during these periods. Three dataset comparisons indicate that dabbling duck body mass was greater in 2006–2008 than earlier years and the increase was greater in the Sacramento Valley and Suisun Marsh than in the San Joaquin Valley, differed among species (mallard [ Anas platyrhynchos ], northern pintail [ Anas acuta ], America wigeon [ Anas americana ], green-winged teal [ Anas crecca ], and northern shoveler [ Anas clypeata ]), and was greater in ducks harvested late in the season. Change in body mass also varied by age–sex cohort and month for all 5 species and by September–January rainfall for all except green-winged teal. The random effect of year nested in period, and sometimes interacting with other factors, improved models in many cases. Results indicate that improved habitat conditions in the Central Valley have resulted in increased winter body mass of dabbling ducks, especially those that feed primarily on seeds, and this increase was greater in regions where area of post-harvest flooding of rice and other crops, and wetland area, has increased. Conservation programs that continue to promote post-harvest flooding and other agricultural practices that benefit wintering waterfowl and continue to restore and conserve wetlands would likely help maintain body condition of wintering dabbling ducks in the Central Valley of California.

California↗

USGS2015

Genetic diversity and host specificity varies across three genera of blood parasites in ducks of the Pacific Americas Flyway

Birds of the order Anseriformes, commonly referred to as waterfowl, are frequently infected by Haemosporidia of the genera Haemoproteus , Plasmodium , and Leucocytozoon via dipteran vectors. We analyzed nucleotide sequences of the Cytochrome b (Cyt b ) gene from parasites of these genera detected in six species of ducks from Alaska and California, USA to characterize the genetic diversity of Haemosporidia infecting waterfowl at two ends of the Pacific Americas Flyway. In addition, parasite Cyt b sequences were compared to those available on a public database to investigate specificity of genetic lineages to hosts of the order Anseriformes. Haplotype and nucleotide diversity of Haemoproteus Cyt b sequences was lower than was detected for Plasmodium and Leucocytozoon parasites. Although waterfowl are presumed to be infected by only a single species of Leucocytozoon , L . simondi , diversity indices were highest for haplotypes from this genus and sequences formed five distinct clades separated by genetic distances of 4.9%–7.6%, suggesting potential cryptic speciation. All Haemoproteus and Leucocytozoon haplotypes derived from waterfowl samples formed monophyletic clades in phylogenetic analyses and were unique to the order Anseriformes with few exceptions. In contrast, waterfowl-origin Plasmodium haplotypes were identical or closely related to lineages found in other avian orders. Our results suggest a more generalist strategy for Plasmodium parasites infecting North American waterfowl as compared to those of the genera Haemoproteus and Leucocytozoon .

PLoS ONE↗