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At least 235 records · Page 13Linked to original sources
USGS2014

Risks of avian influenza transmission in areas of intensive free-ranging duck production with wild waterfowl

For decades, southern China has been considered to be an important source for emerging influenza viruses since key hosts live together in high densities in areas with intensive agriculture. However, the underlying conditions of emergence and spread of avian influenza viruses (AIV) have not been studied in detail, particularly the complex spatiotemporal interplay of viral transmission between wild and domestic ducks, two major actors of AIV epidemiology. In this synthesis, we examine the risks of avian influenza spread in Poyang Lake, an area of intensive free-ranging duck production and large numbers of wild waterfowl. Our synthesis shows that farming of free-grazing domestic ducks is intensive in this area and synchronized with wild duck migration. The presence of juvenile domestic ducks in harvested paddy fields prior to the arrival and departure of migrant ducks in the same fields may amplify the risk of AIV circulation and facilitate the transmission between wild and domestic populations. We provide evidence associating wild ducks migration with the spread of H5N1 in the spring of 2008 from southern China to South Korea, Russia, and Japan, supported by documented wild duck movements and phylogenetic analyses of highly pathogenic avian influenza H5N1 sequences. We suggest that prevention measures based on a modification of agricultural practices may be implemented in these areas to reduce the intensity of AIV transmission between wild and domestic ducks. This would require involving all local stakeholders to discuss feasible and acceptable solutions.

Poyang Lake↗
USGS1995

Accumulation in and effects of lead and cadmium on waterfowl and passerines in northern Idaho

Waterfowl and passerines in northern Idaho in 1987 had high levels of lead in their blood and tissues that originated primarily from mining and smelting activities. Four Canada geese ( Branta canadensis ) and one common goldeneye ( Bucephala clangula ) found dead contained 8 to 38 μg/g (wet mass) of lead in their livers. These levels exceed the lower lethal limit of 5 μg/g in experimental birds. Two of the Canada geese (one each from the contaminated and reference areas) died with ingested lead shotgun pellets (shot) in their gizzards, whereas the other three birds from the contaminated area contained no ingested shot and evidently died from ingesting environmental lead in sediment or biota. Lead burdens in most American robins ( Turdus migratorius ) and mallards ( Anas platyrhynchos ) were high, whereas those in tree swallows ( Tachycineta bicolor ) were slightly elevated. Lead accumulated to potentially hazardous levels in blood and tissues of some nestling robins (maxima of 0·87 μg/g in blood and 5·6 μg/g in liver) and mallards (maxima of 10·2 μg/g in blood and 2·8 μg/g in liver). In mallards, lead levels and associated physiological characteristics of blood were significantly different in juveniles (HY) versus adults (AHY). Activity of δ-aminolevulinic acid dehydratase (ALAD) was about 87 to 95% lower than values for control birds in experimental studies. Activity of ALAD was significantly inversely correlated with blood lead levels. Cadmium was detected in kidneys of most birds, but even the maximum concentration of 7·5 μg/g in an AHY mallard was below known harmful levels.

Idaho↗
USGS2018

Temperature-influenced energetics model for migrating waterfowl

Climate and weather affect avian migration by influencing when and where birds fly, the energy costs and risks of flight, and the ability to sense cues necessary for proper navigation. We review the literature of the physiology of avian migration and the influence of climate, specifically temperature, on avian migration dynamics. We use waterfowl as a model guild because of the ready availability of empirical physiological data and their enormous economic value, but our discussion and expectations are broadly generalizable to migratory birds in general. We detail potential consequences of an increasingly warm climate on avian migration, including the possibility of the cessation of migration by some populations and species. Our intent is to lay the groundwork for including temperature effects on energetic gains and losses of migratory birds with the expected consequences of increasing temperatures into a predictive modeling framework. To this end, we provide a simulation of migration progression exclusively focused on the influence of temperature on the physiological determinants of migration. This simulation produced comparable results to empirically derived and observed values for different migratory factors (e.g., body fat content, flight range, departure date). By merging knowledge from the arenas of avian physiology and migratory theory we have identified a clear need for research and have developed hypotheses for a path forward.

Ecological Modelling↗
USGS2022

Nest remains are insufficient to identify predators of waterfowl nests

Context: Nest predation is a leading cause of nest failure for most ground-nesting birds. Methods that allow for accurate classification of fate and identification of predators are important for understanding productivity and conservation strategies. Past studies have used a visual inspection of nest remains to determine nest fate and predict predator identity. Most formal assessments of these methods have addressed small-bodied birds nesting in trees or shrubs, and have revealed that use of evidence at nests can be relatively accurate for determining nest fate but may lead to incorrect conclusions regarding predator identity. However, few have tested the latter hypothesis for larger ground-nesting birds with precocial young. Aim: We aimed to evaluate a classification system developed for determining nest fate and identifying predators of waterfowl nests, at both the scale of individual nests and across the study area. Methods: From 2016 to 2020, we located 989 blue-winged teal ( Spatula discors ), mallard ( Anas platyrhynchos ) and gadwall ( Mareca strepera ) nests in central North Dakota. We placed cameras at a subset of 249 nests and recorded evidence of nest remains at depredated nests. Key results: The most common predators were American badgers ( Taxidea taxus ), followed by striped skunks ( Mephitis mephitis ), raccoons ( Procyon lotor ) and red foxes ( Vulpes vulpes ). Using evidence of nest remains, we determined nest fates with high accuracy (98.0%). However, evidence of nest remains was only sufficient for identifying predators at 50% of nests, and the classification system was correct only 69.7% of the time. The predicted proportion of predators across the study area differed between the classification system and our video evidence as well. Conclusions: The accuracy of predator identifications based upon the classification system that we evaluated was not supported at any scale. Implications: Our results suggest that evidence of nest remains can be used to determine nest fate for large-bodied precocial, ground-nesting birds, but accurate identification of nest predators will require alternative methods such as nest cameras.

Wildlife Research↗
USGS2016

Weak support for disappearance and restricted emergence/persistence of highly pathogenic influenza A in North American waterfowl

Krauss et al. (1) use lack of detection of highly pathogenic (HP) H5 clade 2.3.4.4 (henceforth "H5") influenza A viruses (IAVs) from >22,000 wild bird samples collected in North America in 2014–2015 to argue that HP H5 IAVs disappeared from waterfowl and that unresolved mechanisms restrict emergence and perpetuation of HP IAVs in natural reservoir species. Here we offer an alternative interpretation.

Proceedings of the National Academy of Sciences↗
USGS2022

Avian influenza antibody prevalence increases with mercury contamination in wild waterfowl

Environmental contamination is widespread and can negatively impact wildlife health. Some contaminants, including heavy metals, have immunosuppressive effects, but prior studies have rarely measured contamination and disease simultaneously, which limits our understanding of how contaminants and pathogens interact to influence wildlife health. Here, we measured mercury concentrations, influenza infection, influenza antibodies, and body condition in 749 individuals from 11 species of wild ducks overwintering in California. We found that the odds of prior influenza infection increased more than five-fold across the observed range of blood mercury concentrations, while accounting for species, age, sex, and date. The prevalence of influenza infection was also higher in species with higher average mercury concentrations. We detected no relationship between influenza infection and body fat content. This positive relationship between influenza prevalence and mercury concentrations in migratory waterfowl suggests that immunotoxic effects of mercury contamination could promote the spread of avian influenza along migratory flyways, especially if influenza has minimal effects on bird health and mobility. More generally, these results show that the effects of environmental contamination could extend beyond the geographic area of contamination itself by altering the prevalence of infectious diseases in highly mobile hosts.

Proceedings of the Royal Society B↗
USGS2023

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

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.

Functional Ecology↗
USGS2016

How will predicted land-use change affect waterfowl spring stopover ecology? Inferences from an individual-based model

Habitat loss, habitat fragmentation, overexploitation and climate change pose familiar and new challenges to conserving natural populations throughout the world. One approach conservation planners may use to evaluate the effects of these challenges on wildlife populations is scenario planning. We developed an individual-based model to evaluate the effects of future land use and land cover changes on spring-migrating dabbling ducks in North America. We assessed the effects of three Intergovernmental Panel on Climate Change emission scenarios (A1B, A2 and B1) on dabbling duck stopover duration, movement distances and mortality. We specifically focused on migration stopover duration because previous research has demonstrated that individuals arriving earlier on the nesting grounds exhibit increased reproductive fitness. Compared to present conditions, all three scenarios increased stopover duration and movement distances of agent ducks. Although all three scenarios presented migrating ducks with increased amounts of wetland habitat, scenarios also contained substantially less cropland, which decreased overall carrying capacity of the study area. Synthesis and applications . Land-use change may increase waterfowl spring migration stopover duration in the midcontinent region of North America due to reduced landscape energetic carrying capacity. Climate change will alter spatial patterns of crop distributions with corn and rice production areas shifting to different regions. Thus, conservation planners will have to address population-level energetic implications of shifting agricultural food resources and increased uncertainty in yearly precipitation patterns within the next 50 years.

Journal of Applied Ecology↗
USGS1991

Seasonal patterns of prey availability and the foraging behavior of arctic foxes ( Alopex lagopus ) in a waterfowl nesting area

The foraging behavior of arctic foxes was observed in a waterfowl nesting area on the Yukon–Kuskokwim Delta of Alaska in 1985–1986. Observations were made during peak fox activity from two towers, 3 m high, located in different community types. Data were collected continuously for individual foxes on specific activities, the community in which activities occurred, and the type of food obtained. After migratory birds started nesting in the area, the food potentially available to foxes changed from microtines, old caches, and carrion to include eggs and birds. This change was reflected in the foraging behavior of the foxes as they switched to predation on eggs. After nesting began, the search success rate of foxes increased (from <30% to >50%) and search duration decreased (mean 19.7 s before nest initiation versus mean 9.4 s in mid-incubation) as the rate of food acquisition increased. Over 80% of the eggs taken by foxes were cached rather than eaten immediately, which extended the availability of this temporally limited resource to foxes. Eggs were the primary prey of arctic foxes during the nesting stages in both years, even though microtine populations were high in one year (1985) and low in the other (1986).

Alaska↗
USGS2016

Detection, prevalence, and transmission of avian hematozoa in waterfowl at the Arctic/sub-Arctic interface: co-infections, viral interactions, and sources of variation.

Background: The epidemiology of avian hematozoa at high latitudes is still not well understood, particularly in sub-Arctic and Arctic habitats, where information is limited regarding seasonality and range of transmission, co-infection dynamics with parasitic and viral agents, and possible fitness consequences of infection. Such information is important as climate warming may lead to northward expansion of hematozoa with unknown consequences to northern-breeding avian taxa, particularly populations that may be previously unexposed to blood parasites. Methods: We used molecular methods to screen blood samples and cloacal/oropharyngeal swabs collected from 1347 ducks of five species during May-August 2010, in interior Alaska, for the presence of hematozoa, Influenza A Virus (IAV), and IAV antibodies. Using models to account for imperfect detection of parasites, we estimated seasonal variation in prevalence of three parasite genera (Haemoproteus, Plasmodium, Leucocytozoon) and investigated how co-infection with parasites and viruses were related to the probability of infection. Results: We detected parasites from each hematozoan genus in adult and juvenile ducks of all species sampled. Seasonal patterns in detection and prevalence varied by parasite genus and species, age, and sex of duck hosts. The probabilities of infection for Haemoproteus and Leucocytozoon parasites were strongly positively correlated, but hematozoa infection was not correlated with IAV infection or serostatus. The probability of Haemoproteus infection was negatively related to body condition in juvenile ducks; relationships between Leucocytozoon infection and body condition varied among host species. Conclusions: We present prevalence estimates for Haemoproteus, Leucocytozoon, and Plasmodium infections in waterfowl at the interface of the sub-Arctic and Arctic and provide evidence for local transmission of all three parasite genera. Variation in prevalence and molecular detection of hematozoa parasites in wild ducks is influenced by seasonal timing and a number of host traits. A positive correlation in co-infection of Leucocytozoon and Haemoproteus suggests that infection probability by parasites in one or both genera is enhanced by infection with the other, or that encounter rates of hosts and genus-specific vectors are correlated. Using size-adjusted mass as an index of host condition, we did not find evidence for strong deleterious consequences of hematozoa infection in wild ducks.

Parasites & Vectors↗
USGS2019

GPS tracking data reveals daily spatio-temporal movement patterns of waterfowl

Background Spatio-temporal patterns of movement can characterize relationships between organisms and their surroundings, and address gaps in our understanding of species ecology, activity budgets, bioenergetics, and habitat resource management. Highly mobile waterfowl, which can exploit resources over large spatial extents, are excellent models to understand relationships between movements and resource usage, landscape interactions and specific habitat needs. Methods We tracked 3 species of dabbling ducks with GPS-GSM transmitters in 2015–17 to examine fine-scale movement patterns over 24 h periods (30 min interval), dividing movement pathways into temporally continuous segments and spatially contiguous patches. We quantified distances moved, area used and time allocated across the day, using linear and generalized linear mixed models. We investigated behavior through relationships between these variables. Results Movements and space-use were small, and varied by species, sex and season. Gadwall ( Mareca strepera ) generally moved least (FFDs: 0.5–0.7 km), but their larger foraging patches resulted from longer within-area movements. Pintails ( Anas acuta ) moved most, were more likely to conduct flights > 300 m, had FFDs of 0.8–1.1 km, used more segments and patches per day that they revisited more frequently, resulting in the longest daily total movements. Females and males differed only during the post-hunt season when females moved more. 23.6% of track segments were short duration (1–2 locations), approximately 1/3 more than would be expected if they occurred randomly, and were more dispersed in the landscape than longer segments. Distance moved in 30 min shortened as segment duration increased, likely reflecting phases of non-movement captured within segments. Conclusions Pacific Flyway ducks spend the majority of time using smaller foraging and resting areas than expected or previously reported, implying that foraging areas may be highly localized, and nutrients obtainable from smaller areas. Additionally, movement reductions over time demonstrates behavioral adjustments that represent divergent energetic demands, the detection of which is a key advantage of higher frequency data. Ducks likely use less energy for movement than currently predicted and management, including distribution and configuration of essential habitat, may require reconsideration. Our study illustrates how fine-scale movement data from tracking help understand and inform various other fields of research.

California↗
USGS1988

Empirical estimates of body drag of large waterfowl and raptors

Measurements of the body frontal area of some large living waterfowl (Anatidae) and raptors (Falconiformes) were found to vary with the two-thirds power of the body mass, with no distinction between the two groups. Wind tunnel measurements on frozen bodies gave drag coefficients ranging from 0·25 to 0·39, in the Reynolds number range 145 000 to 462000. Combining these observations with those of Prior (1984) , which extended to lower Reynolds numbers, a practical rule is proposed for choosing a value of the body drag coefficient for use in performance estimates.

Journal of Experimental Biology↗
USGS2000

Effects of roadside transect width on waterfowl and wetland estimates

Strip transects located along roads are commonly used to estimate waterfowl populations and characterize associated wetland habitat. We used data collected in May and early June, 1995, on forty-five 40-km 2 plots in North Dakota to evaluate bias of 800-m and 400-m wide roadside transects for sampling wetlands relative to a larger (40-km 2 ) scale and to compare duck abundance at the two widths. Densities of all basins combined and of seasonal basins considered alone were biased high for both transect widths, but mean bias did not differ from zero for temporary or semipermanent basins. Biases did not occur when excavated seasonal and temporary basins (i.e., road ditches) were excluded from the sample. Mean basin density was higher for the inner (400-m) transect width than for the outer transect width (area remaining of the 800-m transect, outside of center 400-m width) for all basins combined and for seasonal and temporary basins. We detected an area-related bias in the occurrence of basins in transects: smaller basins (0.08–1.6 ha) were over-represented in transect samples by 2.9–6.5%, and larger basins (≥11 ha) were under-represented in 800-m transects by 7.3% and in 400-m transects by 16.3%. We compared the distribution of ducks relative to water conditions in the inner and outer transect widths to evaluate whether they were affected by proximity to the road. Mallards ( Anas platyrhynchos L.), northern pintails ( A. acuta L.), and gadwall ( A. strepera L.) responded to water conditions equally in the inner and outer transect widths, but northern shovelers ( A. clypeata L.) and blue-winged teal ( A. discors L.) responded more strongly to wetlands on the inner than the outer transect width, indicating that estimates of these species would be higher from a 400-m wide transect than from an 800-m wide transect. Differences in an adjustment index, used to account for the portion of basin obscured from view, were highly variable between inner and outer transect widths but did not indicate that use of wider transects was hampered by visibility. Biases of transect sampling need to be carefully considered when extrapolating wetland basin or duck densities from transects to larger landscape scales.

Wetlands↗
USGS1981

Asiatic clam (Corbicula manilensis) and other foods used by waterfowl in the James River, Virginia

Corbicula manilensis was found in the gizzards of 24 ducks of 5 species taken from the James River, Virginia, between 1973 and 1976. Percent average volume in these species ranged from trace to 6%. This is the first known occurrence of this exotic clam in the food of duck in Chesapeake Bay. A total of 135 other food items was identified from the 116 gizzards of 9 species that were examined. Food that predominated included Cyperus spp., Leersia oryzoides, Polygonum spp., and Zea mays . The great diversity of food consumed in this fresh tidal section of the James River indicates the high value of these wetlands to waterfowl.

Virginia↗
USGS1981

An outbreak of duck virus enteritis (duck plague) in a captive flock of mixed waterfowl

An outbreak of duck virus enteritis occurred in a flock of captive waterfowl composed of mallards ( Anas platyrhynchos ), black ducks ( Anas rubripes ), and Canada geese ( Branta canadensis ). Although all three species were housed together, morbidity and mortality were confined to the 227 black ducks and Canada geese, of which 180 died and the rest were left in a weakened condition. Lesions are given for 20 black ducks and 4 Canada geese dying from DVE. In addition, both horizontal and vertical transmission are discussed as possible sources of the virus that caused this outbreak.

California, Nebraska, Nevada↗
USGS1990

Kidney lesions associated with mortality in chickens inoculated with waterfowl influenza viruses

Seventy-six type A influenza viruses recovered from waterfowl in Wisconsin, California, South Dakota, Florida, Texas, Alabama, and Nebraska were tested for virulence in chickens. The challenge to chickens was intravenous inoculation of first-, second-, or third-egg-passage virus. Each of the virus strains was tested separately in three or four chickens. Eighteen of the 76 viruses caused the death of one or more chickens following inoculation. Postmortem lesions were similar in all dead birds. In decreasing order of frequency, gross lesions included: swollen kidneys evident as accentuated lobular patterns, urates in the pericardial sac, and urates on the surface of the liver. Microscopic lesions present in kidneys were consistent with visceral gout. Mortality was associated with inoculations having higher concentrations of infectious virus. These results indicate that the influenza A viruses circulating in duck populations may include strains potentially pathogenic for chickens.

Alabama, California, Florida, Nebraska, South Dako↗