Polysticta Stelleri Research Articles

Prey availability and foraging activity by tundra-nesting sea ducks: Strong preference for specific wetland types.

Wetlands in Arctic tundra support abundant breeding waterbirds. Wetland types differing in area, depth, vegetation, and invertebrate biomass density may vary in importance to birds, and in vulnerability to climate change. We studied availability and use of different wetland types by prelaying females of four species of sea ducks (Mergini) breeding on the Arctic Coastal Plain of Alaska, USA: long-tailed ducks (Clangula hyemalis) and Steller's (Polysticta stelleri), spectacled (Somateria fischeri), and king eiders (Somateria spectabilis). All four species preferred shallow vegetated wetlands versus deeper lakes. The ducks spent almost all their active time feeding, but their occurrence in different wetland types was not affected by the relative biomass density of known prey or of all invertebrates that we sampled combined. Sea ducks strongly preferred wetlands dominated by emergent and submersed Arctophila fulva over those dominated by the sedge Carex aquatilis, despite the much greater number, total area, and invertebrate biomass density of Carex wetlands. The hens depend heavily on local invertebrate prey for protein to produce eggs; thus, their preference for Arctophila wetlands likely reflects greater accessibility of prey in the near-surface canopy and detritus of Arctophila. Such shallow wetlands decreased substantially in number (-17%) and area (-30%) over 62 years before 2013 and appear highly susceptible to further declines with climate warming. Impacts on sea ducks of climate-driven changes in availability of important wetland types will depend on their adaptability in exploiting alternative wetlands.

Climate change and coastal wetland salinization: Physiological and ecological consequences for Arctic waterfowl

Abstract Coastal wetland salinization related to warming climate has the potential to impact ecological systems globally. In Alaska, the Yukon‐Kuskokwim Delta (YKD) supports large concentrations of breeding water birds and is an ecologically important area for conservation of migratory bird biodiversity. On the YKD, the majority of waterfowl nest in low elevation coastal tundra where storm surges drive saline water into terrestrial wetland habitats. Because newly hatched water birds lack functional salt glands to process saline water, salinization may negatively impact their growth and survival. We investigated potential demographic impacts of wetland salinization by conducting controlled physiological experiments to determine consequences of saline water exposure to spectacled Somateria fischeri and Steller's eider Polysticta stelleri ducklings, and analysed habitat suitability based on experimentally defined tolerance thresholds and sampled wetland salinity levels. We found physiological and behavioural pathologies in <1 week old ducklings at exposure levels of 6 parts per thousand (ppt), and found some evidence of reduced growth in ducklings first exposed after 1 week of age. We conclude that the acute toxicity threshold for ducklings <1 week of age is ≤6 ppt. We found that the area of coastal tundra where wetland salinity exceeded 6 ppt varied considerably among years, suggesting that some portion of the breeding range is unsuitable for rearing ducklings in some years. However, we also found that most eiders in most years nested in areas with salinity at or exceeding the tolerance threshold for ducklings, suggesting that nesting eiders do not appear to avoid saline habitats. We suggest that localized fresh water refugia currently may allow resilience to salinization during the critical period. Understanding how species and habitats respond to climate driven changes is essential for predicting future patterns of distribution and abundance, and is necessary for making informed decisions about conservation priorities. Our study provides insights into the extent of wetland salinization in Alaska, mechanism of impact and current ecological consequences on avian communities depending on these habitats. With ongoing climate change, the probability of species crossing physiological tolerance thresholds of wetland salinity may change in the future. Read the free Plain Language Summary for this article on the Journal blog.

Trace Elements in Blood of Sea Ducks from Dutch Harbor and Izembek Lagoon, Alaska

Abstract In 2001, we collected whole blood from sea ducks—Steller's eider Polysticta stelleri, harlequin duck Histrionicus histrionicus, black scoter Melanitta nigra, and long-tailed duck Clangula hyemalis—wintering at Dutch Harbor, Alaska, and from Steller's eiders molting at Izembek Lagoon on the Alaska Peninsula. Analysis of blood samples was done for 19 trace elements, of which 17 were detected in one or more samples. In Steller's eiders, mean concentrations of six trace elements (As, B, Fe, Hg, Se, and Mo) were greater at Dutch Harbor and mean concentrations of four trace elements (Cr, Cu, Mg, and Zn) were greater at Izembek Lagoon. Among sea ducks at Dutch Harbor, mean concentrations of five trace elements (Cu, Hg, Se, Zn, and V) differed by species: Steller's eiders had greater concentrations of Cu, Zn, and V in their blood; black scoters had the highest concentration of Se; and harlequin ducks had the highest Hg level, with a mean concentration slightly above a threshold effect level. One Steller's eider and one harlequin duck from Dutch Harbor had blood Pb levels above background concentrations. We have no observations to indicate that concentrations of these trace elements were associated with adverse effects.

Use of marine vs. freshwater proteins for egg‐laying and incubation by sea ducks breeding in Arctic tundra

AbstractUnderstanding dietary nutrient sources is fundamental to conserving sensitive species, especially as climate change alters food web dynamics. Migratory species that depend on both marine and terrestrial habitats face unique challenges, as the locations and quality of resources in the two realms may respond quite differently to environmental changes, with potential for spatial and temporal carryover effects. For sea ducks (Mergini) that winter at sea but move inland to breed, body size may determine their capacity to store nutrient reserves for later use in alternative habitats. We assessed ultimate sources of protein for reproduction in four sea duck species in northern Alaska: smaller‐bodied Long‐tailed Ducks and Steller's Eiders (Clangula hyemalis and Polysticta stelleri), and larger‐bodied Spectacled and King Eiders (Somateria fischeri and Somateria spectabilis). To assess the relative use of local freshwater foods vs. marine protein for both egg production and body maintenance of incubating females, we measured stable isotopes of carbon and nitrogen in egg membranes, red blood cells, marine and freshwater invertebrates, and vegetation. For egg production, isotope mixing models indicated that proteinaceous egg membranes of all four species were derived mostly (89%–95%) from freshwater foods on the breeding grounds, with broad individual variation in specific prey types selected by the larger species. For incubation, isotopes in red blood cells indicated that body maintenance of females also relied mainly (87%–91%) on freshwater foods in Long‐tailed Ducks and Steller's Eiders. However, incubating Spectacled and King Eiders obtained only about 60% of their protein from freshwater foods and the remainder from marine‐derived body tissues. The latter strategy allows the larger‐bodied species to incubate almost continuously, whereas the smaller species must take more frequent incubation breaks and generally incur higher rates of predation on eggs. Thus, depending on body size, cross‐seasonal effects of feeding conditions in marine habitats may strongly influence population processes well after the birds move to inland nesting sites. Although conservation programs on land and sea are often researched, planned, and administered by different agencies and organizations, our results emphasize the need to coordinate marine and land‐based efforts for species that integrate conditions across both environments.

Phylogenomics reveals ancient and contemporary gene flow contributing to the evolutionary history of sea ducks (Tribe Mergini)

Insight into complex evolutionary histories continues to build through broad comparative phylogenomic and population genomic studies. In particular, there is a need to understand the extent and scale that gene flow contributes to standing genomic diversity and the role introgression has played in evolutionary processes such as hybrid speciation. Here, we investigate the evolutionary history of the Mergini tribe (sea ducks) by coupling multi-species comparisons with phylogenomic analyses of thousands of nuclear ddRAD-seq loci, including Z-sex chromosome and autosomal linked loci, and the mitogenome assayed across all extant sea duck species in North America. All sea duck species are strongly structured across all sampled marker types (pair-wise species ΦST > 0.2), with clear genetic assignments of individuals to their respective species, and phylogenetic relationships recapitulate known relationships. Despite strong species integrity, we identify at least 18 putative hybrids; with all but one being late generational backcrosses. Most interesting, we provide the first evidence that an ancestral gene flow event between long-tailed ducks (Clangula hyemalis) and true Eiders (Somateria spp.) not only moved genetic material into the former species, but likely generated a novel species — the Steller’s eider (Polysticta stelleri) — via hybrid speciation. Despite generally low contemporary levels of gene flow, we conclude that hybridization has and continues to be an important process that shifts novel genetic variation between species within the tribe Mergini. Finally, we outline methods that permit researchers to contrast genomic patterns of contemporary versus ancestral gene flow when attempting to reconstruct potentially complex evolutionary histories.

Use of genetic mark-recapture to estimate breeding site fidelity and philopatry in a threatened sea duck population, Alaska-breeding Steller’s eiders

The Steller’s eider Polysticta stelleri is a sea duck that breeds in Arctic tundra regions of Russia and Alaska (USA). The Alaska-breeding population is listed as ‘threatened’ under the US Endangered Species Act because of a perceived contraction of the breeding range in North America. Understanding demography of the listed population is critical for evaluating measures that can lead to increased abundance and thus, long-term viability. Specifically, estimates of return rates to breeding areas by adult females and natal areas by juvenile females are needed for planning effective recovery actions. We used a suite of polymorphic loci to genotype individuals and generated genetic profiles of nesting females and female offspring from nest materials collected between 1995 and 2016 in a ~170 km2 study area near Utqiagvik, Alaska. We analyzed capture histories of genetically identified individuals to estimate breeding site fidelity, temporary emigration, and philopatry. From a sample of 365 nests, we found that breeding site fidelity of adult females was high (0.91 ± 0.07 SE), and temporary emigration was also high (0.77 ± 0.06) and annually variable (range 0.34-0.97). From egg shell remains of 124 hatched females, we observed 9 recaptures as nesting adults, suggesting that philopatry was also high (range 0.6-1.0). Given the relatively high rates of adult female breeding site fidelity and female philopatry that we estimated, management actions that reduce mortality of adult females and increase annual productivity are likely to help maintain the population of a few hundred breeding Steller’s eiders on the Arctic Coastal Plain of Alaska.

Winter distribution of Steller's Eiders in the Varangerfjord, northern Norway

Arctic warming and decreasing sea-ice cover along the Siberian coast in the Arctic Ocean leads to greater accessibility for operations such as oil drilling and traffic of tankers. This implies increasing risks for Steller’s Eider Polysticta stelleri wintering, moulting and staging along the coasts of the Varanger Peninsula, Norway. Steller’s Eiders were surveyed by monthly counts during winter and early spring 2016/2017 to investigate numbers and distribution throughout the winter. The highest number of wintering Steller’s Eiders was found in January, representing ~7 % of the European population. In February–April numbers were lower, but at a rather stable level. We found relatively little variation in distribution between months, although the birds were more evenly distributed along the coast later in winter. Mean flock size was significantly larger in January than in March and April. Feeding behaviour was exclusively observed in shallow water, generally at depths of up to 6 m. Areas of focus for an oil pollution emergency plan are pointed out and discussed.

Interspecific patterns of trace elements in sea ducks: Can surrogate species be used in contaminants monitoring?

As industrial development, aerial deposition of pollutants, and chemical releases from thawing permafrost increase in the Arctic, there is need to monitor exposure to contaminants in a range of species. Surrogate or bioindicator species are often used to represent groups of taxa and are typically selected for their wide geographic ranges and ease of sampling. However, it is seldom known how well surrogates exemplify different species, ages, or breeding stages in different areas. We examined multiple trace elements in incubating females of five sea duck species (long-tailed ducks Clangula hyemalis, Steller’s eiders Polysticta stelleri, spectacled eiders Somateria fischeri, king eiders S. spectabilis, and common eiders S. mollissima), in pre-laying spectacled eiders, and in brood-rearing female spectacled and king eiders and their ducklings, among four areas on the Arctic Coastal Plain of Alaska, USA. For Se, Cd, and Cu that are probably acquired during the nonbreeding period, Se and Cd in the blood of hens varied appreciably among species, whereas all species appeared to regulate Cu at similar concentrations. Levels of blood Hg and Pb sampled during incubation were inconsistent among species, apparently reflecting variable exposure on breeding areas. During incubation, species of similar body mass had similar patterns of elements. Se, Cu, and Pb differed substantially across the breeding season in spectacled eiders, as well as between ducklings and hens of spectacled and king eiders. Although analysis of feathers avoids invasive sampling, patterns of element concentrations in feathers differed from those in blood. Species of comparable body mass and life history traits sampled at a given site generally had similar concentrations of trace elements in blood, suggesting some utility as surrogates, but still showed regional variation. Our results suggest that for sea ducks, surrogate species of varying body mass and life history traits may not consistently reflect levels of exposure across taxa, or even among congeners or sex-age classes in the same areas. Biomonitoring for contaminants should use species of comparable mass as indicators at small spatial scales, but at the regional scale, should focus on specific taxa of concern.

Immune parameters in different age classes of captive male Steller's eiders (Polysticta stelleri)

The immune system is important for host defense against antigens, but little is known about Steller's eider (Polysticta stelleri) immunology. This study compared hematological parameters, serum protein levels, lymphocyte proliferation, heat shock protein levels and oxidative damage in four different age classes of captive male Steller's eiders. The hatch year cohort had significantly higher total white blood cell and lymphocyte counts. The second year cohort had significantly higher albumin, alpha globulins and lymphocyte proliferation, and significantly lower beta globulin levels. The 9 year old males had a significantly higher IgY:IgY(ΔFc) ratio. The oldest eiders in the study, 14 + year old males, had significantly higher serum IgY, pre-albumin and glutathione reductase activity, and the lowest lymphocyte proliferation. This study provided a baseline of immune parameters in captive male Steller's eiders, and the results suggested the parameters were influenced by age-related changes.

Evaluating models of population process in a threatened population of Steller's eiders: a retrospective approach

AbstractThe Alaskan breeding population of Steller's eiders (Polysticta stelleri) was listed as threatened under the Endangered Species Act in 1997 in response to declines in abundance and a contraction in their breeding and nesting range. Aerial surveys suggest the breeding population is small and breeds in highly variable numbers, with zero birds counted in five of the last 25 years. The primary objective of this research was to evaluate competing population process models of Alaskan breeding Steller's eiders through comparison of model projections to aerial survey data. To evaluate model efficacy and estimate demographic parameters, we used a Bayesian state‐space modeling framework and fit each model to counts from the annual aerial surveys using sequential importance sampling/resampling. The results strongly support that the Alaskan breeding population experiences population‐level non‐breeding events, and is open to exchange with the larger Russian‐Pacific breeding population. Current recovery criteria for the Alaskan breeding population rely heavily on the ability to estimate population viability. Our results provide an informative model of population process that can be used to examine future population states and assess the population in terms of the current recovery and reclassification criteria.

Ecology and Conservation of North American Sea DucksEcology and Conservation of North American Sea Ducksedited by Jean-Pierre L. Savard, Dirk V. Derksen, Dan Esler, and John M. Eadie.Studies in Avian BiologyNumber 46. 2015. Cooper Ornithological Society, and CRC Press, Boca Raton, Florida. xxii + 584 pp., 4 color plates, 98 text figures. $119.96 (hardcover). ISBN 13:978-1-4822-4897-5.

The editors of this volume have accomplished a remarkable assemblage of authors and topics on the sea duck tribe (Mergini) that has not been covered before in a single major treatise. While waterfowl (Anseriformes) are, arguably, the family of wild birds that have been most thoroughly studied by scientists, the sea ducks have been relatively poorly covered because of the remote habitats in which most of them are found at all times of the year. Only a few, such as the Common Goldeneye (Bucephala clangula), Barrow’s Goldeneye (B. islandica), Bufflehead (B. albeola), and Hooded Merganser (Lophodytes cucullatus) are accessible fairly easily to researchers. The other 11 extant species nest primarily in boreal, Arctic, or sub-Arctic habitats, and typically winter in even more remote oceanic locations. Nevertheless, waterfowl are one of the best inventoried of all North American birds, and sea ducks have been the subject of several additional surveys designed to monitor specific populations (Chapter 1). Most sea duck populations are uncommon, and many have been declining in number to the point that North American populations of two of the eiders, Spectacled (Somateria fischeri) and Steller’s (Polysticta stelleri), are listed under the U.S. Endangered Species Act. In Canada, eastern populations of Harlequin duck (Histrionicus histrionicus) and Barrow’s goldeneye (Bucephala islandica) are Species of Concern. The most significant upshot of this growing concern has been the formation of the Sea Duck Joint Venture of the North American Waterfowl Management Plan in 1998 (Sea Duck Joint Venture Management Board 2008, Sea Duck Joint Venture 2013). This has provided a superb forum for the sea duck specialists of the world to meet, plan, coordinate, and implement new science and to take other steps to stimulate progress in sea duck conservation. The 27 authors of this volume represent essentially all the individuals and government agencies and academic institutions that have driven the tremendous progress made since 1998. The fifteen chapters cover every major topic that one would expect. This is a departure from the more typical approach to taxonomic groups which usually cover each topic on a species-by-species basis. This was a thoughtful tactic as it encourages the broader community of scientists to integrate sea duck information into their analyses while, at the same time, provides important new perspectives for those more narrowly focused on waterfowl. Some new information is provided and the literature reviewed is thorough with all the common sources cited. In addition, a great deal of less common material is integrated by specialists in the general topics. These qualities contribute importantly to the editors’ central objective ‘‘to highlight

鳥取県におけるコケワタガモ<i>Polysticta stelleri</i>の日本最南端記録

鳥取県におけるコケワタガモ<i>Polysticta stelleri</i>の日本最南端記録

Distribution and movements of Alaska-breeding Steller's Eiders in the nonbreeding period

ABSTRACT Steller's Eiders (Polysticta stelleri) that breed in Alaska, USA, are listed as threatened under the U.S. Endangered Species Act (ESA), yet the degree to which these individuals segregate during the nonbreeding period from conspecifics that nest in Russia is unknown. Likewise, very little is known about the timing of use and distribution of autumn migration routes, stopover sites, and molting and wintering areas by the Alaska-breeding population. To address this information need, we implanted 14 Steller's Eiders with satellite transmitters in 2000 and 2001 at their primary Alaskan breeding grounds near Barrow. We found no evidence for segregation of the Alaska-breeding population in midwinter because locations were well-distributed along the Alaska Peninsula, congruent with prevailing knowledge about the wintering distribution of Steller's Eiders that breed in Russia. During the wing molt, from late August to early October, 7 of 13 individuals used Kuskokwim Shoals, corroborating the importance o...

Seasonal Movements and Distribution of Steller’s Eiders (<i>Polysticta stelleri</i>) Wintering at Kodiak Island, Alaska

We used satellite telemetry in 2004–06 to describe the annual movements and habitat use of a segment of the Pacific population of Steller’s Eiders ( Polysticta stelleri ) that winters at Kodiak Island, Alaska. Information about broad-scale patterns of seasonal distribution and links among annual cycle stages is critical for interpreting population trends and developing conservation strategies. We captured birds in Chiniak Bay at Kodiak Island in late February and early March and monitored the movements after departure from Kodiak Island of 24 satellite-tagged birds: 16 after-second-year (ASY) age class females, one second-year age class female, and seven ASY males. All birds used the same intercontinental migration corridor during spring, but routes and chronology of spring migration appeared to vary by year and among individuals. Sixteen of the 24 birds that were tracked migrated to breeding areas along the Arctic coast of Russia from the Chukotka Peninsula to the Taymyr Peninsula; five birds, assumed to be non-breeding, spent the summer in nearshore waters of Russia and Alaska; and the remaining three birds either died during spring migration or had failed transmitters. Thirteen birds were tracked to molt sites that were broadly distributed along the coast of Alaska. Molt sites included St. Lawrence Island, the Kuskokwim Shoals, Kamishak Bay, and three sites along the Alaska Peninsula. Twelve of these 13 birds returned to Kodiak Island to winter, and a single male wintered on the Alaska Peninsula. Steller’s Eiders marked during winter at Kodiak Island were widely distributed during the breeding season, but a large proportion of marked birds returned to molting and wintering areas in two years of the study.

The Body Size-Dependent Diet Composition of North American Sea Ducks in Winter

Daily food requirements scale with body mass and activity in animals. While small species of birds have higher mass-specific field metabolic rates than larger species, larger species have higher absolute energy costs. Under energy balance, we thus expect the small species to have a higher energy value diet. Also the weight and time constraints for flighted and diurnal foragers should set a maximum to the amount of prey items taken in one meal and to the daily number of meals, respectively. Further, avoidance of competition causes the species to reduce the amount of shared prey in their diet. Some diet segregation is therefore to be expected between species. We tested these hypotheses and investigated the role of body mass in the diet composition of 12 sea duck species (Somateria mollissima, Somateria spectabilis, Somateria fischeri, Polysticta stelleri, Bucephala clangula, Bucephala islandica, Bucephala albeola, Melanitta nigra, Melanitta perspicillata, Melanitta deglandi, Histrionicus histrionicus and Clangula hyemalis) wintering in North America. This study was based on a literature survey with special emphasis given to the diet data from the former US Bureau of Biological Survey. The data supported our hypothesis that the energy value of winter diet of sea ducks scales negatively with body mass. Diet diversity also scaled negatively with body mass. Our results suggest the existence of a minimum for the energy value of avian diets.

Trends in Annual Survival of Steller’s Eiders Molting at Izembek Lagoon on the Alaska Peninsula, 1993–2006

Izembek Lagoon, located on the Alaska Peninsula, is an important molting area for the Pacific population of Steller’s Eiders (Polysticta stelleri) and was the site of consistent banding effort during 1993–2006. We used Pradel mark-recapture models to estimate annual survival and population growth rates for adult Steller’s Eiders molting at Izembek Lagoon. We designed 32 models that included effects of sex and year on survival, recapture rate, and seniority, as well as potential trends in survival and seniority. The top model incorporated a two-phase trend (1993–98, 1999–2003) in survival and seniority for each sex and fully sex- and year-specific recapture rates. Average annual adult survival was estimated at 0.86 (SE = 0.030) for females and 0.87 (SE = 0.018) for males. Average annual population growth rates since 1998 were estimated to be approximately 1.0 for both sexes. A brief warming event in the Pacific Decadal Oscillation (1997–98) coincided with the lowest estimates of annual survival, while a subsequent return to cooler conditions in the Bering Sea coincided with the highest estimates and an increasing trend in annual survival.

The European wintering population of Steller’s Eider Polysticta stelleri reassessed

SummaryProlonged declines in the number of Steller’s Eider Polysticta stelleri wintering in Europe have raised concerns about the conservation status of the Western Palearctic population. Coordinated helicopter surveys of all known wintering areas in Norway and Russia and ground counts in the Baltic in 2009 found c.27,000 Steller’s Eiders, similar to numbers found during the last such survey in the mid-1990s. However, around 85% of the population now winters in Russia compared to 30–50% then. The reasons for this rapid shift in distribution are unknown but are likely linked to climate change. The continuing small population size, specialist feeding and restricted distribution of Steller’s Eider necessitate continued survey and research to track population changes and provide evidence for conservation management actions to safeguard the species.

Carbon isotopic fractionation in eider adipose tissue varies with fatty acid structure: implications for trophic studies

Carbon isotopic fractionation was investigated in fatty acids (FA) of adipose tissue and blood serum of threatened Steller's eiders (Polysticta stelleri) and spectacled eiders (Somateria fischeri) relative to the FA in their diets. Captive eiders were fed a known diet for 180 days with serum sampled at 60, 120 and 180 days immediately after a 12 fast; adipose was collected at 180 days. Essential FA (EFA) in the adipose showed varying degrees of isotope fractionation (0-4‰), depending on FA structure. The δ(13)C values of long-chain FA 20:5n-3 and 22:6n-3 did not differ from those in the diet, while those of 18:2n-6 and 18:3n-3 were ∼2‰ greater than in the diet. The δ(13)C values of free FA (FFA) in serum were not consistent within individuals or sampling dates; fractionation varied randomly, suggesting that FFA were arising from diet, rather than mobilization from adipose tissue. Discrimination factors were used in combination with a mixing model incorporating FA and lipid concentrations to estimate the diet of eiders fed a binary mixture with contrasting isotopic signatures. Diet estimates varied with FA but mean values closely approximated the actual proportions consumed. By tracking EFA, this study avoided the complications in interpretation arising from isotopic routing of carbon in bulk isotope analyses and serves as a basis for the development of compound-specific isotopic methods to trace dietary input in wild eiders. However, our understanding of the processes contributing to the variation in isotopic signatures of FA in nature is currently limited, and we recommend that future research directions focus on elucidating these mechanisms.

Evidence for limited exchange of avian influenza viruses between seaducks and dabbling ducks at Alaska Peninsula coastal lagoons

Avian influenza virus (AIV) prevalence and sequence data were analyzed for Steller's eiders (Polysticta stelleri) to assess the role of this species in transporting virus genes between continents and maintaining a regional viral reservoir with sympatric northern pintails (Anas acuta). AIV prevalence was 0.2% at Izembek Lagoon and 3.9% at Nelson Lagoon for Steller's eiders and 11.2% for northern pintails at Izembek Lagoon. Phylogenetic analysis of 13 AIVs from Steller's eiders revealed that 4.9% of genes were of Eurasian origin. Seven subtypes were detected, including two also observed in northern pintails. No AIV strains were highly similar (>99%) at all gene segments between species; however, highly similar individual genes were detected. The proportion of highly similar genes was greater within rather than between species. Steller's eiders likely transport AIV genes between continents through long-distance migratory movements. Differences in AIV prevalence, subtype distribution, and the proportion of highly similar genes suggest limited AIV exchange between Steller's eiders and northern pintails at Alaska Peninsula coastal lagoons during autumn.

Molecular typing of Escherichia coli strains associated with threatened sea ducks and near‐shore marine habitats of south‐west Alaska

In Alaska, sea ducks winter in coastal habitats at remote, non-industrialized areas, as well as in proximity to human communities and industrial activity. We evaluated prevalence and characteristics of Escherichia coli strains in faecal samples of Steller's eiders (Polysticta stelleri; n = 122) and harlequin ducks (Histrionicus histrionicus; n = 21) at an industrialized site and Steller's eiders (n = 48) at a reference site, and compared these strains with those isolated from water samples from near-shore habitats of ducks. The overall prevalence of E. coli was 16% and 67% in Steller's eiders and harlequin ducks, respectively, at the industrialized study site, and 2% in Steller's eiders at the reference site. Based on O and H antigen subtyping and genetic characterization by enterobacterial repetitive intergenic consensus polymerase chain reaction and pulsed-field gel electrophoresis, we found evidence of avian pathogenic E. coli (APEC) strains associated with both species and detected E. coli strains carrying virulence genes associated with mammals in harlequin ducks. Steller's eiders that carried APEC had lower serum total protein and albumin concentrations, providing further evidence of pathogenicity. The genetic profile of two E. coli strains from water matched an isolate from a Steller's eider providing evidence of transmission between near-shore habitats and birds.