Waterfowl Populations Research Articles

Birds as reservoirs: unraveling the global spread of Gamma- and Deltacoronaviruses.

Avian migration is a global phenomenon that transcends geographical boundaries. These migratory birds serve as unwitting carriers of diverse Gammacoronaviruses (γ-CoVs) and Deltacoronaviruses (δ-CoVs). While recombination events have been documented among γ-CoVs in avian species and β-CoVs in mammals, evidence for recombination between CoVs of distinct genera remains limited. This minireview examines the prevalence of CoVs in both domestic waterfowl (ducks and geese) and wild bird populations inhabiting various regions. We investigate the dissemination patterns of γ-CoVs and δ-CoVs among these populations, highlighting their shared characteristics. Furthermore, the review explores the intricate web of cross-species transmission of δ-CoVs from wild birds to mammals, with a particular focus on pigs. Understanding the distinct features of CoVs harbored by waterfowl and wild birds and their potential for cross-species transmission is crucial for preparedness and response to future CoV epidemics.

Duckling survival increased with availability of flooded wetland habitat and decreased with salinity concentrations in a brackish marsh

Abstract Waterfowl population recruitment is sensitive to duckling survival. We quantified predator types and survival rates for Anas platyrhynchos (Mallard) and Mareca strepera (Gadwall) ducklings in one of the largest brackish water marshes in western North America (Suisun Marsh, California) using 556 radio-tagged ducklings from 284 broods tracked during the 2016 to 2019 breeding seasons. Overall, 78% of ducklings died and 84% of mortalities occurred < 7 days after hatch. After hatching in upland fields, survival was greater for broods that hatched closer to flooded wetlands; broods had a ≥ 75% chance of surviving the move from the nest to water when nests were located ≤ 140 m from the nearest wetland and ≤ 50% chance of surviving when nests were located ≥ 970 m from the nearest wetland. Predation accounted for 91% of mortalities and was attributed to mammals (27.6%), birds (22.0%), snakes (4.4%), and unknown predators (46.0%). Anas platyrhynchos survival to fledging (54 days) was only 3.2% and 0.9% during 2 drier years and 11.7% and 16.7% during 2 wetter years. Mareca strepera survival to fledging was 9.4% to 11.2% among years. Daily survival rates for ducklings generally increased with the amount of flooded wetlands within 0.5 km (A. platyrhynchos) and 1.0 km (M. strepera) of the nest at hatch. Additionally, survival rates increased with duckling age and body mass at hatch for both species and decreased with hatch date for A. platyrhynchos but not M. strepera, which may be partially due to the earlier onset of A. platyrhynchos nesting. For ducklings that survived the initial move to water, survival rates were negatively correlated with salinity and this effect was more pronounced for younger ducklings. Anas platyrhynchos survival to 7 days post hatch decreased by 9.1% (wetter year) to 31.4% (drier year) when ducklings were in 12 ppt water (99th quantile of cumulative salinity concentrations experienced by ducklings) versus 0.5 ppt water. Mareca strepera survival to 7 days decreased by 7.4% when ducklings were in 12 ppt vs. 0.5 ppt water. Our results suggest that maintaining a network of low salinity wetlands within 1 km of upland nesting sites would likely improve duckling survival rates, especially during the critical 7-day period after hatch.

Isolation and genetic characterization of multiple genotypes of both H5 and H7 avian influenza viruses from environmental water in the Izumi plain, Kagoshima prefecture, Japan during the 2021/22 winter season

In the 2021/22 winter, one H5N1 and nine H5N8 high pathogenicity avian influenza viruses (HPAIVs) of clade 2.3.3.4b were isolated from the water in crane roosts on the Izumi plain, Japan. Additionally, we isolated low pathogenicity avian influenza viruses (LPAIVs) of five subtypes: H1N1, H4N2, H4N6, H7N7, and H10N4. H5N8 HPAIVs belonging to the G2a group were isolated throughout winter, whereas H5N1 HPAIV belonging to the G2b group were isolated only in early winter. These findings suggest co-circulation of both G2a and G2b HPAIVs in early winter. Although two H7N7 LPAIVs were isolated from cranes’ roost water collected on the same day, the gene constellations of the two isolates were clearly different, indicating the contemporary invasion of at least two different genotypes of H7N7 LPAIVs in the Izumi plain. This study underscores the importance of monitoring both HPAIVs and LPAIVs to understand avian influenza virus ecology in migratory waterfowl populations.

Deep Learning Models for Waterfowl Detection and Classification in Aerial Images

Waterfowl populations monitoring is essential for wetland conservation. Lately, deep learning techniques have shown promising advancements in detecting waterfowl in aerial images. In this paper, we present performance evaluation of several popular supervised and semi-supervised deep learning models for waterfowl detection in aerial images using four new image datasets containing 197,642 annotations. The best-performing model, Faster R-CNN, achieved 95.38% accuracy in terms of mAP. Semi-supervised learning models outperformed supervised models when the same amount of labeled data was used for training. Additionally, we present performance evaluation of several deep learning models on waterfowl classifications on aerial images using a new real-bird classification dataset consisting of 6,986 examples and a new decoy classification dataset consisting of about 10,000 examples per category of 20 categories. The best model achieved accuracy of 91.58% on the decoy dataset and 82.88% on the real-bird dataset.

Genetic Characterization of Avian Paramyxovirus Isolated from Wild Waterfowl in Korea between 2015 and 2021.

Avian paramyxoviruses (APMVs) are often carried by wild waterfowl, and the wild waterfowl may play an important role in the maintenance and spread of these viruses. In this study, we investigated APMVs in the population of migratory wild waterfowl from 2015 to 2021 in Korea and analyzed their genetic characteristics. Fourteen viruses were isolated and subsequently identified as APMV-1 (n = 13) and APMV-13 (n = 1). Phylogenetic analysis of the full fusion gene of 13 APMV-1 isolates showed that 10 APMV-1 isolates belonged to the class II sub-genotype I.2, which was epidemiologically linked to viruses from the Eurasian continent, and 3 viruses belonged to class I, which linked to viruses from the USA. The APMV-13 isolates from wild geese in this study were highly homology to the virus isolated from China. Sequence analysis of 14 isolates showed that all isolates had a typical lentogenic motif at the cleavage site. In summary, we identified the wild species likely to be infected with APMV and our data suggest possible intercontinental transmission of APMV by wild waterfowl. Our current study also provides the first evidence for the presence of class I of APMV-1 and APMV-13 in wild waterfowl surveyed in Korea.

Exploring the population dynamics of waterfowl hunters using a mark‐recapture approach

AbstractThe number of waterfowl hunters in the United States has declined since the 1980s despite relatively abundant waterfowl populations and liberal hunting regulations. Programs focused on recruiting, retaining, and reactivating (R3) waterfowl hunters have become important to avoid further losses in traditional revenue for habitat management and protection and political support for waterfowl conservation and management. We focus on 4 waterfowl hunter population vital rates (i.e., recruitment rate, retention probability, license purchase probability, realized population growth rate), which can be used to improve the effectiveness of waterfowl hunter R3 activities and initiatives by providing a deeper understanding of waterfowl hunter population dynamics to determine who programs should target, where programs should be targeted, and finally the evaluation of programs. To do so, we analyzed Nebraska state electronic license data from 2012–2019 using Pradel survival and recruitment models in a mark‐recapture framework. Female waterfowl hunter recruitment was higher than males; however, retention and license purchase probabilities were lower. Recruitment was highest in younger generations and retention highest in older generations. License purchase probabilities were highest among those in the oldest and youngest generations. The availability of hunting opportunity increased license purchase probabilities but had a minimal influence on retention and no association with recruitment. There were weak relationships between rurality and recruitment, and retention and license purchase probabilities. Finally, belonging to Ducks Unlimited was positively associated with higher license purchase and retention probabilities. Targeting an increase in license purchase probability by promoting social support for hunters through conservation organization membership should be a focus of waterfowl hunter R3 efforts to have the greatest influence on increasing waterfowl hunter participation.

Experience in assessing the abundance and spatial distribution of geese on the Taimyr Peninsula using the aerial survey method

The Taimyr Peninsula is a key region for reproduction of waterfowl of European and Asian wintering populations. The uniqueness of Taimyr is that birds migrate there from both the west and the east, following five out of eight global flyways: East Atlantic, Black Sea/Mediterranean, West Asian/East African, Central Asian, and East Asian/Australasian. The study develops the topic of conservation ornithology and sustainable use of biological resources raised at the First All-Russian Ornithological Congress by Dr. Evgeny Syroechkovsky. Russia lacks the system of state monitoring and assessment of waterfowl populations, in particular with the use of aerial survey methods. In 2019, counts of geese in the tundra zone of the Taimyr Peninsula were carried out from the board of an ultralight aircraft specially designed for aerial surveys. New data on the abundance and spatial distribution of geese were obtained. We substantiated the methodology for the survey flight routing with no transects and the use of GIS, remote sensing, and generalized additive models (GAM) for interpreting the results and extrapolating estimates of goose abundance. A database of the results of aerial surveys was compiled (http://rggsurveys.ru). According to our estimate, for the first time made by statistical modeling for the tundra zone of the Taimyr Peninsula, more than 1.5 million White-fronted geese, about 450000 Bean geese, 78400 Red-breasted geese, and 43000 Lesser White-fronted geese nest and moult on Taimyr. Comparison of these figures with modern estimates of the world populations of these species demonstrates the key role of the Taimyr Peninsula in maintaining populations of rare and economically important Anseriformes.

Global avian influenza situation (2019–2022). Host range expansion asevidence of high pathogenicity avian influenza virus evolution

High pathogenicity avian influenza has a significant negative impact on poultry farming, international trade and health of wild bird populations, therefore the infection requires the utmost attention of the entire international community. The article investigates the evolutionary and epidemic processes observed in recent years in many countries of the world where avian influenza outbreaks occur; describes the ways of the infection spread; the prevalence of the virus types for the last several years, as well as the expansion of the host range, including among representatives of the Mammalia class. The change in the ratio between the virus types starting from 2020, when H5N8 subtype was responsible for the overwhelming number of the disease outbreaks reported, until 2022, when an obvious predominance of H5N1 subtype was detected is demonstrated. A noticeable expansion of the disease-affected areas in Central and South America, the influence of migration, anthropogenic and other factors on influenza spread are highlighted. The conditions facilitating the occurrence of the infection outbreaks affecting mammals, wild animals and livestock, zoo and companion animals are described. Cases of mammals’ infection on the North American and Eurasian continents in zoos, nature parks, backyards and fur farms, asa rule, coincide in time with the infection outbreaks in waterfowl populations. The WAHIS data were analyzed and the high ability of the virus to spillover from birds to mammals, such as martens (minks, otters, ferrets, badgers), cats (domestic cats, cougars, leopards, lynxes), pinnipeds (common seals, grey seals), bears (brown, grizzly, American black), bottlenose dolphins, skunks, foxes, opossums, raccoons was demonstrated. Changes in the habitats of both migratory birds and mammals, including due to some human economic activities, add an ecological and urban component to the complex task of the control and prevention of the epidemic, also posing a potential threat to humans.

An agent-based model to quantify energetics, movement and habitat selection of mid-continent mallards in the Mississippi Alluvial Valley

The dynamics of wintering waterfowl populations at the landscape scale are the result of complex interactions of environmental, behavioral and energetic drivers. Agent-based models provide a method to directly link these factors in a spatially explicit framework and allow the emergence of patterns from the aggregation of individual agent actions. We adapted the Spatially-explicit Waterbird Agent-based Model Program (SWAMP), originally developed for waterfowl in central California, to simulate a basin-scale population of mallards (A. platyrhynchos) wintering in the Mississippi Alluvial Valley over a four-month period (November–February). Simulated agents move within the landscape, foraging on areas made available based on a probabilistic inundation status, and converting food resources to endogenous energy. The model uses a high-resolution map of eastern Arkansas waterfowl habitats and incorporates a hierarchical habitat selection system that enables mallards to relocate at increasing scales in response to changing food availability. We validated the performance of modeled mallard body condition and behavioral metrics under a range of environmental conditions against expected outcomes derived from empirical data and found that the simulation produced realistic representations of changes in flight distances, energy expenditure, lipid storage, and foraging habitat use in response to depleting food resources over time. We discuss the model's applicability as a tool to quantify waterfowl response to a range of environmental conditions and to evaluate scenarios of landscape composition and configuration in the context of waterfowl population management.

Influence of sanctuary disturbance, weather, and landscape characteristics on waterfowl harvest opportunity in western Tennessee

AbstractThe North American Waterfowl Management Plan (NAWMP) recognizes waterfowl hunters and non‐consumptive users as important stakeholders to sustain waterfowl populations through economic and political support for habitat conservation initiatives. Opportunities to shoot at and harvest ducks are key determinants of achievement‐oriented hunt satisfaction and quality. Therefore, identifying factors influencing harvest opportunity would help hunters and wildlife managers identify optimal days afield and promote hunter recruitment, retention, and reactivation (R3) efforts in support of NAWMP. Waterfowl extensively use spatial sanctuaries during hunting seasons, especially diurnally, which could limit their perceived availability to hunters. Thus, a possible management action to support R3 is allowing limited public access on sanctuaries, which could offer diverse recreational opportunities for non‐consumptive users and potentially increase harvest opportunities for hunters in traditional hunting areas if the limited disturbance caused waterfowl to leave sanctuaries. Therefore, we evaluated to what extent experimental sanctuary disturbance, landscape characteristics, and weather influenced local harvest opportunities. We conducted disturbance treatments including travel by a covered truck (i.e., truck with enclosed cab), a pedestrian on foot, and an uncovered vehicle (e.g., motor boat or all‐terrain vehicle [ATV]). To measure harvest opportunity, we used autonomous recording units (ARU) to enumerate daily shotgun volleys at a landscape‐scale across western Tennessee, USA, during 2019–2021 waterfowl hunting seasons. We identified 339,391 distinct shotgun volleys ( = 73 shotgun volleys/day/ARU). Shotgun volleys decreased 50% within 2 weeks of opening day and did not notably increase for the remainder of the hunting season. Contrary to our predictions, sanctuary disturbance decreased harvest opportunity. Specifically, the pedestrian disturbance and covered vehicle disturbance decreased daily shotgun volleys by 32% and 31%, respectively. Additionally, harvest opportunity decreased 20% with every 5‐km increase in distance from a sanctuary. Harvest opportunity increased 2% for every 1°C decrease from mean low temperatures and 9% with every 10‐hPa increase in barometric pressure from the previous day. Conversely, harvest opportunity was unaffected by changes in cloud cover, daily precipitation, waterfowl abundance, or surface water inundation. Our results suggest disturbing sanctuaries decreases harvest opportunity and, in turn, may reduce hunt quality and satisfaction. If increasing harvest opportunity is a primary management objective, we recommend limiting sanctuary disturbance to maximize local harvest opportunities. Furthermore, greater harvest opportunity nearer sanctuaries indicates that additional disturbance‐free areas may increase local harvest opportunities and hunter satisfaction.

Waterfowl populations decline with nutrient reduction and increase with nutrient restoration: 20 years of adaptive management at a Ramsar-listed wastewater treatment plant

Nutrients such as nitrogen and phosphorus are typically considered detrimental to wetland values, but waterfowl can be numerous on nutrient-rich wetlands. Waterfowl were counted three to six times per year on nine treatment lagoons and associated wetlands (2,025 ha) at the Western Treatment Plant (south-east Australia) from 2000, to help maintain ecological values of this Ramsar-listed wetland as well as treating sewage for a large city (Melbourne). Up to 185,000 waterfowl were counted, varying with season, continental rainfall and lagoon operation. Nutrient levels were reduced on Lake Borrie lagoon in 2005 (as part of an Environmental Improvement Program) and restored in 2015. Waterfowl declined on Lake Borrie lagoon from 2005 when it received treated effluent not raw sewage, and increased in 2015 when it received partially treated sewage. This pattern was highly significant for total waterfowl and most species and guilds at Lake Borrie but was not replicated on other lagoons. Modelling revealed positive relationships between waterfowl numbers and nutrient concentrations, including ammonia and nitrite, to moderate levels. This shows that with careful management nutrient enrichment can have positive benefits, allowing artificial wetlands such as wastewater treatment plants to support high densities of waterbirds and the food webs that sustain them.

Newly emerged genotypes of highly pathogenic H5N8 avian influenza viruses in Kagoshima prefecture, Japan during winter 2020/21.

During the 2020/21 winter season, 29 and 10 H5N8 high pathogenicity avian influenza viruses (HPAIVs) were isolated from environmental water and wild birds, respectively, in Kagoshima prefecture, Japan. Furthermore, seven subtypes of low pathogenicity avian influenza viruses (LPAIVs) were also isolated; H1N1, H2N9, H3N2, H3N6, H3N8, H4N6, and H6N6 subtypes. While the H5 hemagglutinin (HA) genes of the G1 cluster were isolated throughout the winter season, those of the G2 cluster were also detected in late winter, suggesting that H5 HPAIVs possessing H5 HA genes from the two different clusters were individually introduced into Kagoshima prefecture. Intriguingly, genetic constellations revealed that the H5N8 HPAIVs could be classified into six genotypes, including four previously reported genotypes (E1, E2, E3, and E7), and two new genotypes (tentatively named E8 and E9). The PB1 and PA gene segments of genotypes E8 and E9 shared high similarity with those of LPAIVs, whereas the remaining gene segments were close to those of genotype E1. Furthermore, LPAIVs whose PA gene segment was close to that of genotype E9 were isolated from the environmental water. Overall, we revealed that various HPAIV genotypes circulated in Kagoshima prefecture during the 2020/21 winter season. This study highlights the importance of monitoring both HPAIV and LPAIV to better understand AIV ecology in migratory waterfowl populations.

Wetland management practices and secretive marsh bird habitat in the Mississippi Flyway: a review

AbstractManagement regimes on publicly owned freshwater wetlands in the Mississippi Flyway of North America (i.e., Flyway) have historically emphasized waterfowl, but there is limited information on how waterfowl‐focused wetland management affects other wetland‐dependent wildlife. Secretive marsh birds (SMBs) depend on wetlands with emergent vegetation throughout their migratory life cycle and often encounter vegetation and water conditions resulting from waterfowl‐focused management regimes. Thus, there is a need for better understanding of how SMBs are affected by wetland management and the extent to which waterfowl‐focused management regimes provide habitat for SMBs. In this review, we identify the vegetation and water conditions resulting from typical management objectives on freshwater emergent wetlands in the Flyway, review and qualitatively synthesize results from studies that directly evaluate how wetland management practices affect SMBs or their habitat, and assess how the vegetation and water conditions being produced for target species (mainly waterfowl) align with SMB habitat requirements. We searched online databases and used Google Scholar to locate peer‐reviewed literature, technical reports, and graduate theses that pertained to responses of SMBs or their habitat to water‐level manipulation, herbicide application, prescribed fire, disking, mowing, and planting crops. There are several management strategies that complement SMBs and waterfowl, such as reducing cover of woody species and providing flooded emergent vegetation. We also highlight management strategies that may not currently align with SMB life‐cycle needs and suggest adjustments that might promote habitat for SMBs while still achieving waterfowl population objectives. For example, adjusting the dates and duration of spring water‐level drawdowns on a portion of wetlands within a larger complex can provide for spring migrating waterfowl and ensure habitat for migrating and nesting SMBs. Ideally, future studies would address how modifications to management practices affect SMBs and monitor potential effects on waterfowl, resulting in a more holistic approach to wetland management.

Waterfowl Wintering in Cities of Temperate Climatic Zone and Its Shaping Factors.

The dynamics of the population size and species diversity of wintering waterfowl was for the first time studied in 30 cities of Russia over eight years. The total population size increased by 35%. The species diversity was found to reach 32 species in total. The mallard Anas platyrhynchos dominated in all 30 cities. The cities grouped to form seven clusters significantly differing from each other by the total parameter set. The geographical location and climatic characteristics of a city are the main environmental conditions for both people and birds. The variance of the wintering waterfowl population size was determined to the extent of 93% by the area and human population size of the city; and 62% of the variance in species number was determined by the longitude, the average January temperature, and the human population size of the city (p < 0.001). The population size and species number of birds correlated with the "age" of the wintering place (p < 0.05). If the urbanization rate continues the same, the population size and species diversity are expected to grow further.

Waterfowl distribution and productivity in the Prairie Pothole Region of Canada: tools for conservation planning

AbstractSpecies conservation requires an understanding of the factors and interactions affecting species distribution and behavior, habitat availability and use, and corresponding vital rates at multiple temporal and spatial scales. Opportunities to investigate these relationships across broad geographic regions are rare. We combined long‐term waterfowl population surveys, and studies of habitat use and breeding success, to develop models that identify and incorporate these interactions for upland‐nesting waterfowl in the Prairie Pothole Region (PPR) of Canada. Specifically, we used data from the annual Waterfowl Breeding Population and Habitat Survey (1961–2009) at the survey segment level and associated habitat covariates to model and map the long‐term average duck density across the Canadian PPR. We analyzed nest location and fate data from approximately 25,000 duck nests found during 3 multi‐year nesting studies (1994–2011) to model factors associated with nest survival and habitat selection through the nesting season for the 5 most common upland nesting duck species: mallard (Anas platyrhynchos), gadwall (Mareca strepera), blue‐winged teal (Spatula discors), northern shoveler (Spatula clypeata), and northern pintail (Anas acuta). Duck density was highly variable across the Canadian PPR, reflecting positive responses to local wetland area and count, and amounts of cropland and grassland, a regional positive response to latitude, and a negative response to local amounts of tree cover. Nest survival was affected by temporal and spatial variables at multiple scales. Specifically, nest survival demonstrated interactive effects among species, nest initiation date, and nesting cover type and was influenced by relative annual wetness, population density, and surrounding landscape composition at landscape scales, and broad geographic gradients (east‐west and north‐south). Likewise, species‐specific probability of nest habitat selection was influenced by timing of nest initiation, population density, relative annual wetness, herbaceous cover, and tree cover in the surrounding landscape, and location within the Canadian PPR. We combined these models, with estimates of breeding effort (nesting, renesting, and nest attempts) from existing literature, in a stochastic conservation planning model that estimates nest distribution and success given spatiotemporal variation in duck density, habitat availability, and influential covariates. We demonstrate the use of this model by examining various conservation planning scenarios. These models allow estimation of local, landscape, and regional influence of conservation investments and other landscape changes on the productivity of breeding duck populations across the PPR of Canada. These models lay the groundwork for the incorporation of conservation delivery costs for full return‐on‐investment analyses and scenario analyses of climate, habitat, and land use change in regional and continental population models.

The Drying Peace–Athabasca Delta, Canada: Review and Synthesis of Cryo-Hydrologic Controls and Projections to Future Climatic Conditions

The Peace–Athabasca Delta (PAD) in northern Alberta, Canada is one of the world’s largest inland freshwater deltas, home to large populations of waterfowl, muskrat, beaver, and free-ranging wood bison. The delta region has been designated a Ramsar wetland of international importance and is largely located within the Wood Buffalo National Park, itself being a UNESCO World Heritage Site. Indigenous residents have depended on the delta for centuries to sustain their culture and lifeways. In the past five decades, the PAD has experienced prolonged dry periods in-between rare floods, accompanied by reduction in the area covered by lakes and ponds that provide habitat for aquatic life. Recharge of the higher-elevation, or “perched”, basins depends on overland flooding generated by major spring ice jams that occasionally form in the lower reaches of the Peace and Athabasca Rivers and in their various distributaries. Indigenous Traditional Knowledge and Historical Records for the unregulated Athabasca River are relatively scarce, but conclusively demonstrate the role of ice jams in replenishing perched basins of the Athabasca sector of the PAD. Similar information, coupled with extensive hydrometric and observational data for the regulated Peace River have enabled elucidation of the physical mechanisms that lead to ice-jam flooding of the Peace sector and assessment of regulation impacts on flood frequency. Such understanding can inform design of remedial strategies to moderate or arrest the drying trend of the delta. Climate-related projections to future scenarios suggest reduced frequency of ice-jam floods, albeit with uncertainty.

Migration chronology and multi-scale habitat selection of wintering midcontinent greater white-fronted geese

Food resources are assumed to limit waterfowl populations in the Mississippi Alluvial Valley, thus bioenergetic models are used for spatial allocation of food resources to provide adequate energy to support regional waterfowl population objectives. Changes in population abundance and distributions of midcontinent greater white-fronted geese Anser albifrons have implications for region-specific conservation planning of energetic resources for wintering waterfowl. This research aimed to quantify timing of arrival of greater white-fronted geese to wintering areas and quantify foraging behaviors. These data can help refine bioenergetics models and facilitate future waterfowl habitat planning efforts in the region. Bioenergetics models account for energetic demands of wintering geese by assuming they forage in flooded habitats 25% of the time across a 110-day winter planning period. Although this assumption has gone untested, our estimate of time spent foraging in flooded habitats (27.4% ± 5.8%) confirms the current model parameter of 25% of the time. However, we suggest that this is not the best parameter to use in bioenergetics models as greater white-fronted geese in our study foraged in dry habitats (72.6% ± 5.8%) more often than in flooded habitats. In addition, selection for rice fields in heavily weighted toward early winter (November; β = 2.85), and use declined 70% as winter progressed (February; β = 0.89), likely due to depletion of available rice grain, hunting pressure, and the physiological need to switch from a greater carbohydrate diet to a nitrogen-rich diet. In addition, white-fronted geese arrived to wintering areas earlier than current models accounted for with a mean arrival date of 30 October (± 2.5 days) to the Mississippi Alluvial Valley. We suggest early arrival to the wintering area and greater selection for dry rice fields during early winter indicates exploitative competition by white-fronted geese for shared food resources that may not be adequately accounted for in current bioenergetics models. We suggest current models underestimated energetic demands and the competitive nature of early migratory greater white-fronted geese.

Postbreeding movements and molting ecology of female gadwalls and mallards

AbstractThe 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 transmitters with global positioning system and global system for mobile communications (GPS‐GSM) technology to female gadwalls and mallards within Suisun and tracked the birds following the breeding season during 2015–2018. We determined molt locations for 52 female gadwalls and 112 female mallards. Thirty of the marked gadwall females selected 2 regions within southern Oregon‐northeastern California (SONEC) to undergo molt; 16 molted in the Upper Klamath Basin (southern OR) and 14 in the Lower Klamath Basin (northeastern CA). A large portion of female mallards molted in Suisun (n = 34) and the Sacramento Valley in California (n = 31) but also used the Upper Klamath Basin (n = 13), Lower Klamath Basin (n = 12), and the Yolo–Delta region in California (n = 12). On average, gadwalls departed Suisun on 30 July (±17.82 days [SD]), and mallards departed on 24 July (±22.69 days). Mean start date of molt for each species was similar: 27 August (±16.09 days) for gadwalls and 26 August (±21.03 days) for mallards. Molt end date was analogous for each species as well. Molt ended on average 1 October (±15.52 days) for gadwalls and on 5 October (±18.34 days) for mallards. Gadwalls and mallards showed intraspecific differences in average molt start and end date within the 3 main geographical zones: Suisun, Central Valley of California (Central Valley), and SONEC. Mean duration of wing molt for gadwalls was 34.72± 8.62 days and 41.09 ± 12.54 days for mallards. Both species primarily selected permanent marsh to undergo wing molt (gadwalls = 90.4%, mallards = 63.4%). Conservation and active management of these high‐use molting areas used by California's primary breeding waterfowl species could enhance postbreeding survival, leading to increased breeding waterfowl populations.

Genetic Characterization of Avian Influenza Viruses Isolated from the Izumi Plain, Japan in 2019/20 Winter Season.

The Izumi plain in the Kagoshima Prefecture, Japan, is known as an overwintering site for more than 30,000 migratory waterfowl, including endangered crane species. We previously reported that environmental water samples, from artificial wet paddies created as crane roost sites on the Izumi plain, are useful for avian influenza virus (AIV) surveillance. During the 2019/20 winter season, we collected 238 water samples from the crane roost sites and isolated 22 AIVs of six subtypes: one H1N1, one H3N2, seven H3N8, four H4N6, nine H6N6, and one H11N2 subtypes. Genetic analyses revealed that AIVs of the same subtype isolated from the Izumi plain during a single winter season exhibited multiple genetic constellations. Furthermore, phylogenetic analyses suggested that our H3N2 isolate may be a genetic reassortant between close relatives to our H3N8 and H11N2 isolates. Our study highlighted the importance of monitoring AIV circulation to better understand AIV ecology in migratory waterfowl populations.

Heavy metal exposure to a migratory waterfowl, Northern Pintail (Anas acuta), in two peri-urban wetlands

In this study, the heavy metal exposure risk model was employed to assess the exposure risk to a predominantly herbivore waterfowl, Northern Pintail, wintering in two wetland habitats in the Purulia district of West Bengal, located on overlapping Central Asian Flyway (CAF) and East Asian-Australasian Flyway (EAAF). Both wetlands were important staging and roosting grounds for migratory waterfowl for ages. The exposure model was used to quantify the risk of exposure to metals through oral ingestion. Exposure doses of Cu, Zn, Pb, and Cr through food plants ingestion and food-associated sediment consumption pathways were two potent sources of heavy metal exposure in the waterfowl under study. Exposure through water intake was ignored as metals were either of negligible concentrations or below the detection limit in water samples. Heavy metal concentrations showed significant positive correlations between bottom sediment and plant at both sites. At Purulia Sahebbandh (Site 1), the total exposure dose of all four metals was much higher than their conforming tolerable daily intake (TDI), and thereby, the metals might pose threats to the migratory wintering herbivorous waterfowl populations. However, in Adra Sahebbandh (Site 2), total exposure doses of Pb, Zn and Cu were much below their corresponding TDI. The Hazard Quotient (HQ) of Cr was highest followed by nonessential toxic Pb and these two elements could be considered as priority pollutants at Site 1. Prioritize threats were decreased in the following sequence: Cr > Pb > Cu > Zn at Site 1 and Cr > Zn > Pb > Cu at Site 2. Hazard Index was found to be >5 at Site 1 and for much higher metal loads a significant correlation between metal concentrations in plants, bottom sediment and exposure doses were also recorded. Therefore, the peri-urban Purulia Sahebbandh wetland could immediately be considered for risk control and demanded holistic management of important waterfowl habitats.