American Wigeon Research Articles

Variation in diurnal and nocturnal movements distances revealed in wintering dabbling ducks in the Mississippi Alluvial Valley

Movement of waterfowl during winter is central to resource acquisition and mortality avoidance, despite the imminent risk to survival and overall fitness induced by hunting disturbance and energy expenditure. Weather and other environmental conditions may influence movement by altering resource needs, in which ducks must balance the trade‐offs of resource acquisition and risk management. We compared how environmental factors influenced total daily diurnal and nocturnal movement distances of three dabbling duck species wintering in the Mississippi Alluvial Valley. We estimated total daily diurnal and nocturnal movement distances of green‐winged teal (Anas crecca; n = 51), American wigeon (Mareca americana; n = 38), and mallards (Anas platyrhynchos; n = 31) using backpack transmitters during the winter period of February–November 2020–2021 and 2021–2022. We used linear mixed effects models to model the influence of weather, hunt season, day of season, and sex on total diurnal and nocturnal movement distances by species. Green‐winged teal moved 7.7% further during the nocturnal period (x̅ = 3.38 km; SE = 0.32; p < 0.001) than during the diurnal period (x̅ = 3.13 km SE = 0.10), while American wigeon and mallards moved 36.6% (x̅ = 4.95 km; SE = 0.20; p < 0.001) and 28.1% (x̅ = 4.39 km; SE = 0.23; p < 0.001) further during the diurnal period than the nocturnal period (x̅ = 3.42 km, SE = 0.28 and x̅ = 3.31 km, SE = 0.22), respectively. Fine‐scale movement distances during the diurnal period were weakly associated with environmental covariates for all species. Conversely, moon illumination influenced nocturnal movement distances for all species. Nightly movement distances of mallards increased by 2.1 times from new to full moon during the hunting season. Conversely, there were no changes in nocturnal movement distance during pre‐hunt and post‐hunt periods when hunting disturbance was absent. In the face of intensifying environmental pressures on movement patterns in dabbling duck populations, this research demonstrates a behavioral response to moon illumination as a mechanism for moving about the landscape for resource acquisition in the presence of human disturbances that induce risk, such as hunting.

Genome analysis of gyroviruses identified in waterfowl in Arizona (USA).

Gyroviruses are small single-stranded DNA (ssDNA) viruses that are largely associated with birds. Chicken anemia virus is the most extensively studied gyrovirus due to its disease impact on the poultry industry. However, we know much less about gyroviruses infecting other avian species. To investigate gyroviruses infecting waterfowl, we determined six complete genome sequences that fall into three gyrovirus groups, referred to as waterfowl gyrovirus 1 (n = 3), 2 (n = 2), and 3 (n = 1), in organs from hunter-harvested waterfowl from Arizona (USA). The waterfowl gyrovirus 1 variants were identified in multiple organs of a single American wigeon and represent a tentative new species. The waterfowl gyrovirus 2 variants were identified in the livers of two American wigeons and share >70% VP1 nucleotide sequence identity with gyrovirus 9, previously identified in the spleen of a Brazilian Pekin duck (MT318123) and a human fecal sample (KP742975). Waterfowl gyrovirus 3 was identified in a northern pintail spleen sample, and it shares >73% VP1 nucleotide sequence identity with two gyrovirus 13 sequences previously identified in Brazilian Pekin duck spleens (MT318125 and MT318127). These gyroviruses are the first to be identified in waterfowl in North America, as well as in American wigeons and northern pintails.

Ecological and anthropogenic drivers of waterfowl productivity are synchronous across species, space, and time.

Knowledge of interspecific and spatiotemporal variation in demography-environment relationships is key for understanding the population dynamics of sympatric species and developing multispecies conservation strategies. We used hierarchical random-effects models to examine interspecific and spatial variation in annual productivity in six migratory ducks (i.e., American wigeon [Mareca americana], blue-winged teal [Spatula discors], gadwall [Mareca strepera], green-winged teal [Anas crecca], mallard [Anas platyrhynchos] and northern pintail [Anas acuta]) across six distinct ecostrata in the Prairie Pothole Region of North America. We tested whether breeding habitat conditions (seasonal pond counts, agricultural intensification, and grassland acreage) or cross-seasonal effects (indexed by flooded rice acreage in primary wintering areas) better explained variation in the proportion of juveniles captured during late summer banding. The proportion of juveniles (i.e., productivity) was highly variable within species and ecostrata throughout 1961-2019 and generally declined through time in blue-winged teal, gadwall, mallard, pintail, and wigeon, but there was no support for a trend in green-winged teal. Productivity in Canadian ecostrata declined with increasing agricultural intensification and increased with increasing pond counts. We also found a strong cross-seasonal effect, whereby more flooded rice hectares during winter resulted in higher subsequent productivity. Our results suggest highly consistent environmental and anthropogenic effects on waterfowl productivity across species and space. Our study advances our understanding of current year and cross-seasonal effects on duck productivity across a suite of species and at finer spatial scales, which could help managers better target working-lands conservation programs on both breeding and wintering areas. We encourage other researchers to evaluate environmental drivers of population dynamics among species in a single modeling framework for a deeper understanding of whether conservation plans should be generalized or customized given limited financial resources.

Molecular Characterization of Non-H5 and Non-H7 Avian Influenza Viruses from Non-Mallard Migratory Waterbirds of the North American Flyways, 2006-2011.

The surveillance of migratory waterbirds (MWs) for avian influenza virus (AIV) is indispensable for the early detection of a potential AIV incursion into poultry. Surveying AIV infections and virus subtypes in understudied MW species could elucidate their role in AIV ecology. Oropharyngeal-cloacal (OPC) swabs were collected from non-mallard MWs between 2006 and 2011. OPC swabs (n = 1158) that molecularly tested positive for AIV (Cts ≤ 32) but tested negative for H5 and H7 subtypes were selected for virus isolation (VI). The selected samples evenly represented birds from all four North American flyways (Pacific, Central, Mississippi, and Atlantic). Eighty-seven low pathogenic AIV isolates, representing 31 sites in 17 states, were recovered from the samples. All isolates belonged to the North American lineage. The samples representing birds from the Central Flyway had the highest VI positive rate (57.5%) compared to those from the other flyways (10.3-17.2%), suggesting that future surveillance can focus on the Central Flyway. Of the isolates, 43.7%, 12.6%, and 10.3% were obtained from blue-winged teal, American wigeon, and American black duck species, respectively. Hatch-year MWs represented the majority of the isolates (70.1%). The most common H and N combinations were H3N8 (23.0%), H4N6 (18.4%), and H4N8 (18.4%). The HA gene between non-mallard and mallard MW isolates during the same time period shared 85.5-99.5% H3 identity and 89.3-99.7% H4 identity. Comparisons between MW (mallard and non-mallard) and poultry H3 and H4 isolates also revealed high similarity (79.0-99.0% and 88.7-98.4%), emphasizing the need for continued AIV surveillance in MWs.

Diverse Small Circular DNA Viruses Identified in an American Wigeon Fecal Sample.

American wigeons (Mareca americana) are waterfowls that are widely distributed throughout North America. Research of viruses associated with American wigeons has been limited to orthomyxoviruses, coronaviruses, and circoviruses. To address this poor knowledge of viruses associated with American wigeons, we undertook a pilot study to identify small circular DNA viruses in a fecal sample collected in January 2021 in the city of Tempe, Arizona (USA). We identified 64 diverse circular DNA viral genomes using a viral metagenomic workflow biased towards circular DNA viruses. Of these, 45 belong to the phylum Cressdnaviricota based on their replication-associated protein sequence, with 3 from the Genomoviridae family and the remaining 42 which currently cannot be assigned to any established virus group. It is most likely that these 45 viruses infect various organisms that are associated with their diet or environment. The remaining 19 virus genomes are part of the Microviridae family and likely associated with the gut enterobacteria of American wigeons.

Interspecific forced copulations generate most hybrids in broadly sympatric ducks

Although rare, hybrids are more common in broadly sympatric waterfowl than in any other avian family; yet, the behavioral ecology explaining their generation has remained controversial. Leading hypotheses are forced interspecific copulations, mis-imprinting caused by mixed broods, and scarcity of conspecific mates. Using a large sample of hybrid ducks solicited from North American hunters we evaluated these hypotheses by genetically determining the mother and father species of F1 hybrids. Based on abundances in areas where their breeding ranges overlap, the frequency of hybrids varied greatly from expectations, with hybrids between species within recently derived clades being much more frequent than those between more divergent clades. Forced copulations, as measured by large phallus-length asymmetries between parentals, strongly predicted the father species of most F1 hybrids. Thus, most Anas acuta x A. platyrhynchos (Northern Pintail x Mallard) F1s were sired by A. acuta, and most A. platyrhynchos x Mareca strepera (Mallard x Gadwall) F1s were sired by A. platyrhynchos. Siring asymmetries were consistent with phallus length asymmetries in five additional parental combinations, but none had samples large enough to be individually statistically significant. The exception to this trend was our sample of nine A. platyrhynchos x Mareca americana (Mallard x Gadwall) F1s, for which a large phallus asymmetry failed to predict the father species. Hybrids were rare in brood parasitic species, suggesting mis-imprinting to be an unlikely cause of most hybrids; however, our samples of hybrids from regular brood parasites were inadequate to strongly address this hypothesis. We could test the scarcity of mates hypothesis for only a single hybrid combination and it contradicted our prediction: most F1 M. Penelope x M. americana (Eurasian x American Wigeon) were sired by M. penelope, strongly contradicting our prediction that female M. penelope wintering in enormous flocks of M. americana (American Wigeon) on the west coast of North America would have difficulty finding conspecific mates. In general, our results support interspecific forced copulations as the predominant behavioral mechanism generating hybrids in North temperate waterfowl.

Estimating Movement Rates Between Eurasian and North American Birds That Are Vectors of Avian Influenza.

Avian influenza (AI) is a zoonotic disease that will likely be involved in future pandemics. Because waterbird movements are difficult to quantify, determining the host-specific risk of Eurasian-origin AI movements into North America is challenging. We estimated relative rates of movements, based on long-term evolutionary averages of gene flow, between Eurasian and North American waterbird populations to obtain bidirectional baseline rates of the intercontinental movements of these AI hosts. We used population genomics and coalescent-based demographic models to obtain these gene-flow-based movement estimates. Inferred rates of movement between these continental populations varies greatly among species. Within dabbling ducks, gene flow, relative to effective population size, varies from ∼3 to 24 individuals/generation between Eurasian and American wigeons (Mareca penelope and Mareca americana) to ∼100-300 individuals/generation between continental populations of northern pintails (Anas acuta). These are evolutionary long-term averages and provide a solid foundation for understanding the relative risks of each of these host species in potential intercontinental AI movements. We scale these values to census size for evaluation in that context. In addition to being AI hosts, many of these bird species are also important in the subsistence diets of Alaskans, increasing the risk of direct bird-to-human exposure to Eurasian-origin AI virus. We contrast species-specific rates of intercontinental movements with the importance of each species in Alaskan diets to understand the relative risk of these taxa to humans. Assuming roughly equivalent AI infection rates among ducks, greater scaup (Aythya marila), mallard (Anas platyrhynchos), and northern pintail (Anas acuta) were the top three species presenting the highest risks for intercontinental AI movement both within the natural system and through exposure to subsistence hunters. Improved data on AI infection rates in this region could further refine these relative risk assessments. These directly comparable, species-based intercontinental movement rates and relative risk rankings should help in modeling, monitoring, and mitigating the impacts of intercontinental host and AI movements.

Jack but Not John Barth

Jack but Not John Barth R. L. Friedman (bio) I’ve never met John Barth. Jack Barth I know, but John Barth remains a stranger. In 1976, two of my high school English teachers invited me to join them at Emory University for a reading by famed novelist, John Barth. My love of literature was fiery at age 17, which inspired their thoughtful invitation. Barth was a renowned author and even a cult figure, winner of the National Book Award in 1973 for Chimera. One of the teachers suggested I read that work before the Emory event. I tried. I tried again. But the allusions to Dunyazad, Perseus, and Bellerophon were so far beyond my base of knowledge, I was intimidated long before we stepped out of the car on the Emory campus. The auditorium was standing room only. Barth was famous at a time, I suspect, when students cared to tackle complex literary works and try to out-read one another (a phenomenon rendered with wry observance in a passage from The Floating Opera). For literate college students, knowing the intricacies of The Sot-Weed Factor or Giles Goat-Boy was essential. Gaps in one’s ultra-literacy mattered. Before the program began, students chatted fervidly about Barth’s works: the allusions behind New Tammany College, the picaresque bawdiness of Ebenezer Cooke’s adventures, and Ambrose, the sperm who narrates his passage towards the creation of a life. Several commented that Barth helmed the Writing Seminars department at his alma mater, Johns Hopkins. When he was introduced and began reading excerpts from Chimera, I marveled at his attributes: ultra-tall and beyond slender, his bald pate seemed to house a supercomputer. His tone was playful, less like an academic and more akin to a jazz artist riffing on exciting themes. The erudite wordplay enthralled the audience but zoomed so far over my head it cracked the ceiling—all of which inspired me to jump into the author’s works, absorbing them in chronological order. And since the first novel, The Floating Opera, concerned the adventures and existential musings of a Johns Hopkins alumnus, this tidbit added to a growing roster of feedback pointing me towards Baltimore. I figured it out: I would attend Johns Hopkins as an English or Writing Seminars major, and study under John Barth himself. I enrolled at Hopkins. [End Page 169] Then came my first Writing Seminars class. I don’t recall my submission or why the grad student teacher held it in such low regard, but the force of her criticism wounded me far out of proportion to her intents. Hypersensitive, I couldn’t take it. Never again did I take a Writing Sems class outside of playwriting (which was taught by a delightful chemistry professor with a love of theater and no expectations for artistry). Barth was quite a presence on campus. Whenever he strolled by, students whispered in awe. Whenever he held readings, the venues rocked with undergraduates, grad students, teachers, and the wider community. One of my favorite college memories occurred when the novelist and essayist John Gardner came to Hopkins to read from his works. The packed audience in Shriver Hall had come to witness an intellectual scrum. Supporters of Gardner adhered to his belief in literature as a necessary moral force. Supporters of Barth decried any boundaries imposed on literary efforts, preferring the self-referential play of metafiction—of stories acknowledging themselves as fictional forms. What I didn’t know was, regardless of their differences, Barth and Gardner were friends with mutual respect for the other’s output. Gardner read from his work, then opened the floor for questions. And who should raise his hand first but Barth, who challenged Gardner’s conceptions. Gardner smiled, knowing he was behind enemy lines, and quietly outlined his disregard for metafiction. Barth queried further. Gardner reiterated his views, citing examples of what he deemed moral literature versus experimental works. The audience understood that the answer to this dispute lay in their own hands: read what grabs, moves, and entertains you. Which made the give and take between these two giants seem like its own metafiction: we were observers but also participants. I...

Novel viruses belonging to the family Circoviridae identified in wild American wigeon samples.

Members of the family Circoviridae are known to infect several avian species, with the ability to cause severe disease outcomes in some species. Using a high-throughputsequencing-informed approach, we identified two novel lineages of circoviruses, referred to as wigfec circovirus 1 and 2, in faecal matter of American wigeons (Mareca americana) collected in Arizona, USA. Wigfec circovirus 1 was identified in eight samples and is most closely related to the other waterfowl circoviruses, sharing ~64% genome-wide sequence identity with duck circoviruses. On the other hand, wigfec circovirus 2 was identified in two samples and is most closely related to two circoviruses identified in bat samples, sharing ~71% genome-wide pairwise identity. Both novel circoviruses were recovered from samples collected at the same location two months apart. Furthermore, in one sample, both of these viruses were identified, indicating these viruses are likely common amongst these birds and/or their environment.

First Occurrence of Eurasian Wigeon (Mareca penelope L.) in Central México

This study reports an occurrence of Eurasian Wigeon (Mareca penelope) at Lago de Guadalupe in Cuautitlán Izcalli, State of Mexico. In January, February, and March 2021, we documented one individual foraging and swimming. Our observation is the first record of this species in central Mexico, 650 km southwest of the closest prior record in Mexico. We concluded that the Eurasion Wigeon individual probably migrated with American Wigeon (Mareca americana) individuals.

Visibility Bias of Waterbirds During Aerial Surveys in the Nonbreeding Season

ABSTRACTAerial surveys for waterfowl and other waterbirds provide abundance estimates that are commonly used by state and federal agencies for waterfowl and wetland management. However, most existing surveys provide an index of abundance and are uncorrected for visibility bias, which may limit their use in accurately determining local population size. We used concurrent ground and aerial surveys to estimate visibility bias during cruise‐style waterfowl surveys from September through January 2014–2017 along the Illinois River Valley, Illinois, USA. Immediately before an aerial survey, a ground observer counted waterfowl and other waterbirds by species within a distinct survey area and counts were compared with aerial abundance estimates to quantify detection rate and count bias (i.e., visibility bias). Overall, waterfowl guilds had high detection rates and low count bias, resulting in low overall visibility bias (ducks, −11% [SE = 5%]; geese, −8% [SE = 3%]; swans, −5% [SE = 3%]). At the species level, visibility bias varied greatly (e.g., green‐winged teal [Anas crecca], 182% [SE = 221%]; American wigeon [Mareca americana], −74% [SE = 20%]). Group size, species prevalence, cloud cover, and temperature influenced visibility bias, but direction and magnitude of effects were variable among taxa. Low visibility bias for most guilds indicated that well‐designed, cruise‐style aerial surveys with bias estimation techniques provided reliable estimates of population size and have great utility for monitoring waterfowl and other waterbirds as part of an adaptive management framework. © 2021 The Wildlife Society.

Long-term changes in the autumn migration phenology of dabbling ducks in southern Ontario and implications for waterfowl management

Delays in waterfowl autumn migration have been widely reported by hunters and ornithologists throughout North America. The implications of such delays are vast, with potential effects on the efficacy of population management, reduced social and economic opportunities, and reduced resource availability by overuse and over-grazing in key staging areas. In this study, we tested for changes in autumn migration timing for six abundant species of dabbling ducks in southern Ontario, Canada. We applied generalized linear mixed models to test for effects of year and climate indices El Nino Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO) on the Julian date of peak abundance as observed during aerial surveys conducted throughout the lower Great Lakes. Our analyses revealed delays of 11–18 days between 1968 and 2011 for four of six focal species: mallard, American black duck, American wigeon and gadwall. La Nina and El Nino events had no effect on migration timing for American black duck, American green-winged teal or American wigeon, while an increase in the annual NAO index resulted in a delayed migration for American wigeon. There was an NAO:ENSO interaction for mallard and gadwall migration; an increase in NAO advanced peak migration dates during La Nina events. However, an increase in NAO delayed migration for gadwall during the neutral phase of the ENSO and delayed migration for both species during El Nino events. Blue-winged teal and American green-winged teal showed no change in migration timing. Given that climate forecasts indicate continued positive-value phases, the autumn migrations for mallard, American black duck, gadwall and American wigeon may become increasingly delayed. Wildlife managers should use all available data, including from standardized aerial surveys, citizen science and climate models to inform and direct adaptive population management, hunting regulations, wildlife emergency response and habitat conservation.

New avian breeding records for Kugluktuk, Nunavut

New breeding records for 10 species of tundra and boreal nesting birds were documented near the community of Kugluktuk (Nunavut, Canada) over the course of the 2015 and 2016 breeding seasons and incidentally in 2017 and 2018. These species include American Wigeon (Mareca americana), Mallard (Anas platyrhynchos), Northern Shoveler (Anas clypeata), Green-winged Teal (Anas carolinensis), Greater Scaup (Aythya marila), Say’s Phoebe (Sayornis saya), Canada Jay (Perisoreus canadensis), Greycheeked Thrush (Catharus minimus), Yellow-rumped Warbler (Setophaga coronata), and Dark-eyed Junco (Junco hyemalis). Previously unpublished breeding evidence for Bald Eagle (Haliaeetus leucocephalus) is also discussed along with suspected breeding of Barn Swallow (Hirundo rustica), Bohemian Waxwing (Bombycilla garrulus), White-throated Sparrow (Zonotrichia albicollis), and Pine Grosbeak (Pinicola enucleator). These records represent the first described breeding occurrences for these species in the Kitikmeot region, or new records for the mainland of Nunavut. A lack of historical ornithological survey effort in this area has likely led to the diversity of these previously unrecorded breeding observations. These results highlight the need to increase geographic coverage of bird surveys in northern Canada to more accurately delineate the northern limit of breeding ranges and suggest that further formal survey effort will undoubtedly lead to additional new breeding records.

Moving at the speed of flight: dabbling duck-movement rates and the relationship with electronic tracking interval

Abstract Context Effective wildlife management requires information on habitat and resource needs, which can be estimated with movement information and modelling energetics. One necessary component of avian models is flight speeds at multiple temporal scales. Technology has limited the ability to accurately assess flight speeds, leading to estimates of questionable accuracy, many of which have not been updated in almost a century. Aims We aimed to update flight speeds of ducks, and differentiate between migratory and non-migratory flight speeds, a detail that was unclear in previous estimates. We also analysed the difference in speeds of migratory and non-migratory flights, and quantified how data collected at different temporal intervals affected estimates of flight speed. Methods We tracked six California dabbling duck species with high spatio-temporal resolution GPS–GSM transmitters, calculated speeds of different flight types, and modelled how estimates varied by flight and data interval (30min to 6h). Key results Median migratory speeds were faster (but non-significant) for the larger mallard (Anas platyrhynchos; 82.5kmh–1), northern pintail (Anas acuta; 79.0kmh–1) and gadwall (Mareca strepera; 70.6kmh–1), than the smaller-bodied northern shoveler (Spatula clypeata; 65.7kmh–1), cinnamon teal (Spatula cyanoptera; 63.5kmh–1) and American wigeon (Mareca Americana; 52kmh–1). Migratory flights were faster than non-migratory flights for all species and speeds were consistently slower with an increasing data interval. Implications The need to balance time and energy requirements may drive different speeds for migratory and non-migratory flights. Lower speeds at longer intervals are likely to be due to a greater proportion of ‘loafing’ time included in flighted segments, demonstrating that data acquired at different intervals provide a means to evaluate and estimate behaviours that influence speed estimation. Shorter-interval data should be the most accurate, but longer-interval data may be easier to collect over lengthier timeframes, so it may be expedient to trade-off a degree of accuracy in broad-scale studies for the larger dataset. Our updated flight speeds for dabbling duck species can be used to parameterise and validate energetics models, guide management decisions regarding optimal habitat distribution, and, ultimately, improve conservation management of wetlands for waterfowl.

Nonbreeding Duck Use at Central Flyway National Wildlife Refuges

Abstract Within the U.S. portion of the Central Flyway, the U.S. Fish and Wildlife Service manages waterfowl on numerous individual units (i.e., Refuges) within the National Wildlife Refuge System. Presently, the extent of waterfowl use that Refuges receive and the contribution of Refuges to waterfowl populations (i.e., the proportion of the Central Flyway population registered at each Refuge) remain unassessed. Such an evaluation would help determine to what extent Refuges support waterfowl relative to stated targets, aid in identifying species requiring management attention, inform management targets, and improve fiscal efficiencies. Using historic monitoring data (1954–2008), we performed this assessment for 23 Refuges in Texas, New Mexico, Oklahoma, Kansas, and Nebraska during migration and wintering months (October–March). We examined six dabbling ducks and two diving ducks, plus all dabbling ducks and all diving ducks across two periods (long-term [all data] and short-term [last 10 October–March periods]). Individual Refuge use was represented by the sum of monthly duck count averages for October–March. We used two indices of Refuge contribution: peak contribution and January contribution. Peak contribution was the highest monthly count average for each October–March period divided by the indexed population total for the Central Flyway in the corresponding year; January contribution used the January count average divided by the corresponding population index. Generally, Refuges in Kansas, Nebraska, and New Mexico recorded most use and contribution for mallards Anas platyrhynchos. Refuges along the Texas Gulf Coast recorded most use and contribution for other dabbling ducks, with Laguna Atascosa and Aransas (including Matagorda Island) recording most use for diving ducks. The long-term total January contribution of the assessed Refuges to ducks wintering in the Central Flyway was greatest for green-winged teal Anas crecca with 35%; 12–15% for American wigeon Mareca americana, gadwall Mareca strepera, and northern pintail Anas acuta; and 7–8% for mallard and mottled duck Anas fulvigula. Results indicated that the reliance on the National Wildlife Refuge System decreased for these ducks, with evidence suggesting that, for several species, the assessed Refuges may be operating at carrying capacity. Future analyses could be more detailed and informative were Refuges to implement a single consistent survey methodology that incorporated estimations of detection bias in the survey process, while concomitantly recording habitat metrics on and neighboring each Refuge.

Long‐term trends in weather severity indices for dabbling ducks in eastern North America

ABSTRACTAnnual distributions of waterfowl during the nonbreeding period can influence ecological, cultural, and economic relationships. We used previously developed Weather Severity Indices (WSI) that explained migration by dabbling ducks in eastern North America and weather data from the North American Regional Reanalysis to develop an open‐access internet‐based tool (i.e., WSI web app) to visualize and query WSI data. We used data generated by the WSI web app to determine whether the weather known to elicit southerly migration by dabbling ducks had changed, from October to April 1979 to 2013. We detected that the amount of area in the Mississippi and Atlantic Flyways with weather severe enough to cause southerly migration decreased during 1) October–December for American wigeon (Mareca americana), green‐winged teal (Anas crecca), and northern shoveler (Spatula clypeata); 2) December–January for mallard (A. platyrhynchos), American black duck (A. rubripes), and northern pintail (A. acuta); and 3) February–April for mallard, American black duck, gadwall (M. strepera), American wigeon, green‐winged teal, and northern shoveler. Results were consistent with prior research indicating that weather causing autumn and winter migration of dabbling ducks has become increasingly mild in the past 3 decades. The WSI web app enables users to query daily data and maps by species and by Flyway, Joint Venture, Landscape Conservation Cooperative, and State. We encourage those with corresponding data on participation and satisfaction by waterfowl enthusiasts (i.e., birders and hunters) to test for relationships with the WSI because of the implications for conservation funding, especially if autumn and winter weather severity continues to become increasingly mild as predicted. © 2017 The Wildlife Society.

Resource partitioning among five species of waterfowl (Anasspp.) at an autumn migratory stopover: combining stable isotope and mercury biomarkers

The Saskatchewan River Delta (SRD) is North America’s largest inland delta and an important stopover site for waterfowl in the Central Flyway. However, little is known about their basic feeding ecology at this site and how species segregate or overlap in resource use. We used stable carbon (δ13C) and nitrogen (δ15N) isotopes and mercury concentrations ([Hg]) in liver tissue to trace use of local nutrient sources by five waterfowl species and tested for differences in diets among species, sexes, and age groups. Macrophytes were the dominant food source for Northern Pintail (Anas acuta L., 1758) and American Wigeon (Anas americana Gmelin, 1789) with median proportions of 0.86 and 0.98, respectively. There was also evidence of partitioning of resources, as Blue-winged Teal (Anas discors L., 1766) and Green-winged Teal (Anas carolinensis Gmelin, 1789) consumed invertebrates, as did a subset of Mallards (Anas platyrhynchos L., 1758), suggesting that these birds might minimize competition for resources during the short staging period in the SRD when waterfowl densities are high. Other isotopes or tracers, such as [Hg] that varied among sources (0.03–0.20 μg·g–1dry mass) and waterfowl species (0.22–3.19 μg·g–1dry mass), can be used for further refining dietary estimates.

Body Mass, Wing Length, and Condition of Wintering Ducks Relative to Hematozoa Infection

Abstract 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) 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 body condition index 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 genus 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 body condition index than for wing length and indicated that the relationships varied among species, age–sex cohorts, regions, and months. Compared with uninfected ducks, hematozoa-infected duck body mass, wing length, and body condition index was −1.63% (85% CI = −2.79% to −0.47%), −0.12% (−0.41% to 0.17%), and −1.38% (−2.49% to −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 because of 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.

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 (2017) 6, e80; doi:10.1038/emi.2017.66; published online 6 September 2017

First record of American Wigeon Mareca americana in The Gambia and associated records from Kartong Bird Observatory

First record of American Wigeon Mareca americana in The Gambia and associated records from Kartong Bird Observatory