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At least 55 records · Page 3Linked to original sources
USGS2009

Sources and transformations of nitrate from streams draining varying land uses: Evidence from dual isotope analysis

Knowledge of key sources and biogeochemical processes that affect the transport of nitrate (NO 3 - ) in streams can inform watershed management strategies for controlling downstream eutrophication. We applied dual isotope analysis of NO 3 - to determine the dominant sources and processes that affect NO 3 - concentrations in six stream/river watersheds of different land uses. Samples were collected monthly at a range of flow conditions for 15 mo during 2004-05 and analyzed for NO 3 - concentrations, ?? 15 N NO3 , and ?? 18 O NO3 . Samples from two forested watersheds indicated that NO 3 - derived from nitrification was dominant at baseflow. A watershed dominated by suburban land use had three ?? 18 O NO3 values greater than +25???, indicating a large direct contribution of atmospheric NO 3 - transported to the stream during some high flows. Two watersheds with large proportions of agricultural land use had many ?? 15 N NO3 values greater than +9???, suggesting an animal waste source consistent with regional dairy farming practices. These data showed a linear seasonal pattern with a ?? 18 O NO3 :?? 15 N NO3 of 1:2, consistent with seasonally varying denitrification that peaked in late summer to early fall with the warmest temperatures and lowest annual streamflow. The large range of ?? 15 N NO3 values (10???) indicates that NO 3 - supply was likely not limiting the rate of denitrification, consistent with ground water and/or in-stream denitrification. Mixing of two or more distinct sources may have affected the seasonal isotope patterns observed in these two agricultural streams. In a mixed land use watershed of large drainage area, none of the source and process patterns observed in the small streams were evident. These results emphasize that observations at watersheds of a few to a few hundred km 2 may be necessary to adequately quantify the relative roles of various NO 3 - transport and process patterns that contribute to streamflow in large basins. Copyright ?? 2009 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

Journal of Environmental Quality↗
USGS2021

Statistical methods used in research concerning endangered and threatened animal species of Puerto Rico: A meta-study

A concern about statistics in wildlife studies, particularly of endangered and threatened species, is whether the data collected meet the assumptions necessary for the use of parametric statistics. This study identified published papers on the nine endangered and six threatened species found only on Puerto Rico using five different databases. The results from the Zoological Record database identified the most articles, including all identified by the other databases. Of the 222 identified articles, 108 included some form of statistics, 26 used only descriptive statistics, 34 included only parametric statistics, 26 used only nonparametric statistics, and 22 reported both parametric and nonparametric statistical analyses. This meta-study showed that the percentage of articles with no statistical treatment decreased in the most recent 20 years, and that although parametric statistics continue to be the most commonly used in published wildlife studies of Puerto Rican wildlife, there has been a distinct increase in the use of nonparametric statistics over time.

Caribbean Journal of Science↗
USGS1998

Effects of surgically and gastrically implanted radio transmitters on swimming performance and predator avoidance of juvenile chinook salmon ( Oncorhynchus tshawytscha )

Radiotelemetry data are often used to make inferences about an entire study population; therefore, the transmitter attachment method should be the one that least affects the study animal. Juvenile chinook salmon ( Oncorhynchus tshawytscha ) <120 mm in fork length (FL) with either gastrically or surgically implanted transmitters had significantly lower critical swimming speeds than control fish 1 and 19-23 days after tagging. For fish >120 mm FL, fish with gastric implants swam as well as controls 1 day but not 19-23 days after tagging. In contrast, fish with surgical implants swam as well as controls 19-23 days but not 1 day after tagging. During predation trials, fish with gastric or surgical implants were eaten by smallmouth bass ( Micropterus dolomieu ) in significantly greater numbers than controls. We do not recommend implanting transmitters (representing 4.6-10.4% of the fish's body weight) in fish <120 mm FL. Furthermore, surgical implants (representing 2.2-5.6% of the fish's body weight) may be the preferred method for biotelemetry studies of juvenile chinook salmon >120 mm FL.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2007

Diseases of amphibians

The development and refinement of amphibian medicine comprise an ongoing science that reflects the unique life history of these animals and our growing knowledge of amphibian diseases. Amphibians are notoriously fastidious in terms of captive care requirements, and the majority of diseases of amphibians maintained in captivity will relate directly or indirectly to husbandry and management. Investigators have described many infectious and noninfectious diseases that occur among various species of captive and wild amphibians, and there is considerable overlap in the diseases of captive versus free-ranging populations. In this article, some of the more commonly reported infectious and noninfectious diseases as well as their etiological agents and causative factors are reviewed. Some of the more common amphibian diseases with bacterial etiologies include bacterial dermatosepticemia or “red leg syndrome,” flavobacteriosis, mycobacteriosis, and chlamydiosis. The most common viral diseases of amphibians are caused by the ranaviruses, which have an impact on many species of anurans and caudates. Mycotic and mycotic-like organisms cause a number of diseases among amphibians, including chytridiomycosis, zygomycoses, chromomycoses, saprolegniasis, and ichthyophoniasis. Protozoan parasites of amphibians include a variety of amoeba, ciliates, flagellates, and sporozoans Common metazoan parasites include various myxozoans, helminths (particularly trematodes and nematodes), and arthropods. Commonly encountered non-infectious disease etiologies for amphibians include neoplasia, absolute or specific nutritional deficiencies or overloads, chemical toxicities, and inadequate husbandry or environmental management.

ILAR Journal↗
USGS2009

Nitrogen losses from dairy manure estimated through nitrogen mass balance and chemical markers

Ammonia is an important air and water pollutant, but the spatial variation in its concentrations presents technical difficulties in accurate determination of ammonia emissions from animal feeding operations. The objectives of this study were to investigate the relationship between ammonia volatilization and ?? 15 N of dairy manure and the feasibility of estimating ammonia losses from a dairy facility using chemical markers. In Exp. 1, the N/P ratio in manure decreased by 30% in 14 d as cumulative ammonia losses increased exponentially. Delta 15 N of manure increased throughout the course of the experiment and ?? 15 N of emitted ammonia increased (p < 0.001) quadratically from -31??? to -15 ???. The relationship between cumulative ammonia losses and ?? 15 N of manure was highly significant (p < 0.001; r 2 = 0.76). In Exp. 2, using a mass balance approach, approximately half of the N excreted by dairy cows (Bos taurus) could not be accounted for in 24 h. Using N/P and N/K ratios in fresh and 24-h manure, an estimated 0.55 and 0.34 (respectively) of the N excreted with feces and urine could not be accounted for. This study demonstrated that chemical markers (P, K) can be successfully used to estimate ammonia losses from cattle manure. The relationship between manure ?? 15 N and cumulative ammonia loss may also be useful for estimating ammonia losses. Although promising, the latter approach needs to be further studied and verified in various experimental conditions and in the field. Copyright ?? 2009 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

Journal of Environmental Quality↗
USGS2013

Taming wildlife disease: bridging the gap between science and management

1.Parasites and pathogens of wildlife can threaten biodiversity, infect humans and domestic animals, and cause significant economic losses, providing incentives to manage wildlife diseases. Recent insights from disease ecology have helped transform our understanding of infectious disease dynamics and yielded new strategies to better manage wildlife diseases. Simultaneously, wildlife disease management (WDM) presents opportunities for large-scale empirical tests of disease ecology theory in diverse natural systems. 2.To assess whether the potential complementarity between WDM and disease ecology theory has been realized, we evaluate the extent to which specific concepts in disease ecology theory have been explicitly applied in peer-reviewed WDM literature. 3.While only half of WDM articles published in the past decade incorporated disease ecology theory, theory has been incorporated with increasing frequency over the past 40 years. Contrary to expectations, articles authored by academics were no more likely to apply disease ecology theory, but articles that explain unsuccessful management often do so in terms of theory. 4.Some theoretical concepts such as density-dependent transmission have been commonly applied, whereas emerging concepts such as pathogen evolutionary responses to management, biodiversity–disease relationships and within-host parasite interactions have not yet been fully integrated as management considerations. 5.Synthesis and applications. Theory-based disease management can meet the needs of both academics and managers by testing disease ecology theory and improving disease interventions. Theoretical concepts that have received limited attention to date in wildlife disease management could provide a basis for improving management and advancing disease ecology in the future.

Journal of Applied Ecology↗
USGS2011

Use of recent and historical records to estimate status and trends of a rare and imperiled stream fish, Percina jenkinsi (Percidae)

Rarely encountered animals may be present but undetected, potentially leading to incorrect assumptions about the persistence of a local population or the conservation priority of a particular area. The federally endangered and narrowly endemic Conasauga logperch ( Percina jenkinsi ) is a good example of a rarely encountered fish species of conservation concern, for which basic population statistics are lacking. We evaluated the occurrence frequency for this species using surveys conducted with a repeat-observation sampling approach during the summer of 2008. We also analyzed museum records since the late 1980s to evaluate the trends in detected status through time. The results of these analyses provided support for a declining trend in this species over a portion of its historical range, despite low estimated detection probability. We used the results to identify the expected information return for a given level of monitoring where the sampling approach incorporates incomplete detection. The method applied here may be of value where historic occurrence records are available, provided that the assumption of constant capture efficiency is reasonable.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2018

Does behavioural thermoregulation underlie seasonal movements in Lake Erie walleye?

Thermoregulation is presumed to be a widespread determinant of behaviour in fishes, but has not often been investigated as a mechanism shaping long-distance migrations. We used acoustic telemetry and animal-borne thermal loggers to test the hypothesis that seasonal migration in adult walleye ( Sander vitreus ) in Lake Erie is size- and (or) sex-specific and related to behavioural thermoregulation. Female walleye migrated out of the warm, shallow western basin earlier than did males and were 1.8 times more likely to be detected on acoustic receivers in the deeper and cooler eastern basin. The few fish that remained in the western basin were restricted to a smaller range of higher temperatures (≥20 °C) than those that migrated to the central and eastern basins (∼16–21 °C). However, temperature records from walleye in the central basin were nearly indistinguishable from those in the eastern basin, suggesting thermal preferences alone could not explain migration to the eastern basin. As such, our effort to understand the mechanisms that cause migratory behaviours has generated mixed evidence on the role of temperature and that factors like foraging opportunities may have synergistic roles in the migration.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2025

Estimating disease prevalence from preferentially sampled, pooled data

After the onset of the COVID-19 pandemic, scientific interest in coronaviruses endemic in animal populations has increased dramatically. However, investigating the prevalence of disease in animal populations across the landscape, which requires finding and capturing animals can be difficult. Spatial random sampling over a grid could be extremely inefficient because animals can be hard to locate, and the total number of samples may be small. Alternatively, preferential sampling, using existing knowledge to inform sample location, can guarantee larger numbers of samples, but estimates derived from this sampling scheme may exhibit bias if there is a relationship between higher probability sampling locations and the disease prevalence. Sample specimens are commonly grouped and tested in pools which can also be an added challenge when combined with preferential sampling. Here we present a Bayesian method for estimating disease prevalence with preferential sampling in pooled presence-absence data motivated by estimating factors related to coronavirus infection among Mexican free-tailed bats ( Tadarida brasiliensis ) in California. We demonstrate the efficacy of our approach in a simulation study, where a naive model, not accounting for preferential sampling, returns biased estimates of parameter values; however, our model returns unbiased results regardless of the degree of preferential sampling. Our model framework is then applied to data from California to estimate factors related to coronavirus prevalence. After accounting for preferential sampling impacts, our model suggests small prevalence differences between male and female bats.

California↗
USGS2007

Possible refugia in the Alexander Archipelago of southeastern Alaska during the late Wisconsin glaciation

The interpretation of the extent of late Wisconsin glaciation in southeastern Alaska has varied between geologists and biologists. Maps and reports of the region prepared by geologists commonly indicated that late Wisconsin ice extended as a large uniform front west to the edge of the continental shelf. However, the distribution of plants and animals in the region has led many biologists to suggest that there may have been ice-free areas that served as refugia during the late Wisconsin. Based on analyses of aerial photographs, topographic maps, and bathymetric charts, in conjunction with a review of previous literature and reconnaissance fieldwork throughout the region, this study presents data supporting a limited ice extent in the Alexander Archipelago during the late Wisconsin and identifies possible ice-free areas that may have served as refugia. These areas include (1) the Fairweather Ground, (2) the Herbert Graves Island area, (3) the western coast of southern Baranof Island and adjacent continental shelf, (4) Coronation Island and the adjacent continental shelf, (5) the Warren Island area, (6) the continental shelf from west of Heceta Island to Forrester Island in the south, (7) parts of the west coast of southern Dall Island, and (8) lowland areas in southern Prince of Wales Island. The identification of these possible refugia has bearing on the recolonization of the Alexander Archipelago, as they could have served as centers of biotic dispersal upon regional deglaciation and as stepping stones for early humans with a maritime tradition entering the western hemisphere from Asia. ?? 2007 NRC Canada.

Canadian Journal of Earth Sciences↗
USGS2021

Until It's a regulation it's not my fight: Complexities of a voluntary nonlead hunting ammunition program

Wildlife and human health are at risk of lead exposure from spent hunting ammunition. Lead exposure persists for bald eagles due to bullet fragments in game animal gut piles and unretrieved carcasses, and is also a human health risk when wild game is procured using lead ammunition. Programs encouraging the voluntary use of nonlead ammunition have become a popular approach mitigating these effects. This study explored attitudes and experiences of United States Fish and Wildlife Service (USFWS) staff implementing an outreach program encouraging deer hunters to voluntary use nonlead ammunition on 54 National Wildlife Refuges (NWRs) in the Upper Midwest, U.S. to understand factors affecting program implementation. We conducted 29 semi-structured interviews of USFWS staff along with 60 responses from an open-ended survey question. Twelve themes emerged from the data and were grouped into three broad categories: (1) challenges of dealing with complex issues, (2) importance of messengers and messages, and (3) resistance from staff. Challenges of dealing with complex issues included administrative restraint and uncertainty, scope and scale of program, human health not an agency responsibility, contextual political influences, and public-private collaborations. Importance of messengers and messages included the importance of experience, and salience of human health risk. Finally, resistance from staff included skepticism of the science and motives behind the program, competing priorities for refuge staff, differing perceptions of regulatory and voluntary approaches, cost and availability of nonlead ammunition, and disregard by some about lead ammunition and human health risks. Staff identified numerous challenges implementing the program, many of which were external factors beyond the control of the participants. Understanding the factors affecting program implementation may help guide future efforts encouraging the voluntary use of nonlead ammunition.

Illinois, Iowa, Indiana, Michigan, Minnesota, Miss↗
USGS2004

Flow cytometry used to assess genetic damage in frogs from farm ponds

Flow cytometry (FC) is a laboratory method used to detect genetic damage induced by environmental contaminants and other stressors in animals, including amphibians. We tested FC methods on three species of ranid frogs collected from farm ponds and natural wetlands in southeastern Minnesota. We compared FC metrics for Rana clamitans between ponds with direct exposure to agricultural contaminants and reference (unexposed) ponds. Concentrations of atrazine in water from our farm ponds ranged from 0.04 to 0.55 ppb. We found that R. clamitans from exposed ponds had DNA content similar to frogs from unexposed ponds. Pond-averaged C-values (a measure of DNA content) ranged from 6.53 to 7.08 for R. pipiens (n . 13), 6.55 to 6.60 for R. clamitans (n . 40) and 6.74 for R. palustris (n . 5). Among all species, the mean sample CVs ranged from 1.91 (R. palustris) to 6.31 (R. pipiens). Deformities were observed in only 2 of 796 individuals among all species and occurred in both reference and exposed ponds. Although we did not detect evidence of DNA damage associated with agriculture in our study, we demonstrated the potential of FC for screening amphibian populations for genetic damage. Metrics from a variety of amphibian species and locations as well as laboratory studies are needed to further assess the value of FC for monitoring amphibian genetic integrity in contaminated sites.

Journal of the Iowa Academy of Science↗
USGS2008

Environmental occurrence and shallow ground water detection of the antibiotic monensin from dairy farms

Pharmaceuticals used in animal feeding operations have been detected in various environmental settings. There is a growing concern about the impact on terrestrial and aquatic organisms and the development of antibiotic-resistant strains of microorganisms. Pharmaceutical use in milking cows is relatively limited compared with other livestock operations, except for the ionophore monensin, which is given to lactating cows as a feed. By weight, monensin can be the most significant antibiotic used in a dairy farm. This study investigates the potential of monensin to move from dairy operations into the surrounding ground water. Using two dairy farms in California as study sites, we twice collected samples along the environmental pathway-from flush lanes, lagoon waters, and shallow ground water beneath the dairies and beneath its associated manured fields. Monensin concentrations were determined using solid-phase extraction and liquid chromatography-tandem mass spectrometry with positive electrospray ionization. Monensin was detected in all of the flush lane and lagoon water samples. Theoretical maximum concentration estimated from the actual dosing rate and the theoretical excretion rate assuming no attenuation was one order of magnitude greater than observed concentrations, suggesting significant attenuation in the manure collection and storage system. Monensin was also detected, at levels ranging from 0.04 to 0.39 microg L(-1), in some of the ground water samples underneath the production area of the dairy but not from the adjacent manured fields. Concentrations in ground water immediately downgradient of the lagoons were one to two orders of magnitude lower than the concentrations detected in lagoons, suggesting attenuation in the subsurface. The data suggest the possibility of monensin transport into shallow (2-5 m) alluvial ground water from dairy management units, including manure storage lagoons and freestalls occupied by heifers, lactating cows, and dry cows.

Journal of Environmental Quality↗
USGS2015

A new method for discovering behavior patterns among animal movements

Advanced satellite tracking technologies enable biologists to track animal movements at fine spatial and temporal scales. The resultant data present opportunities and challenges for understanding animal behavioral mechanisms. In this paper, we develop a new method to elucidate animal movement patterns from tracking data. Here, we propose the notion of continuous behavior patterns as a concise representation of popular migration routes and underlying sequential behaviors during migration. Each stage in the pattern is characterized in terms of space (i.e., the places traversed during movements) and time (i.e. the time spent in those places); that is, the behavioral state corresponding to a stage is inferred according to the spatiotemporal and sequential context. Hence, the pattern may be interpreted predictably. We develop a candidate generation and refinement framework to derive all continuous behavior patterns from raw trajectories. In the framework, we first define the representative spots to denote the underlying potential behavioral states that are extracted from individual trajectories according to the similarity of relaxed continuous locations in certain distinct time intervals. We determine the common behaviors of multiple individuals according to the spatiotemporal proximity of representative spots and apply a projection-based extension approach to generate candidate sequential behavior sequences as candidate patterns. Finally, the candidate generation procedure is combined with a refinement procedure to derive continuous behavior patterns. We apply an ordered processing strategy to accelerate candidate refinement. The proposed patterns and discovery framework are evaluated through conceptual experiments on both real GPS-tracking and large synthetic datasets.

International Journal of Geographical Information ↗
USGS2023

Global review reveals how disparate study motivations, analytical designs, and focal ions limit understanding of salinization effects on freshwater animals

Global salinization of freshwaters is adversely affecting biotic communities and ecosystem processes. We reviewed six decades (1960–2020) of literature published on animal responses to increased salinities across different taxonomic and ecological contexts and identified knowledge gaps. From 585 journal articles, we characterized 5924 responses of mollusks, crustaceans, zooplankton, non-arthropod invertebrates (NAI), insects, fishes, and amphibians to salinization. Insects and fishes were the most studied taxa; Na + and Cl − were the most studied ions − . Collectively, concentrations of the ions examined typically spanned five orders of magnitude. Species' invasiveness was a key motivation for studying mollusks, crustaceans, and fishes; threats of urbanization and road salts were key motivations for studying NAI, zooplankton, and amphibians. Laboratory studies were more common than field studies for most taxa. Focal life stages in laboratory studies varied widely but juveniles and adults were represented similarly in field studies. Studies of mollusks, NAI, and crustacean focused on adults; studies of zooplankton, insects, fishes, and amphibians focused on juveniles. Organismal- and population-level responses measuring solute uptake, internal chemistry, body condition, or ion concentrations predominated laboratory studies; population- and assemblage-level responses measuring abundance, spatial distribution, or assemblage composition predominated field studies. Negative responses to salinization predominated but positive and unimodal responses were apparent across all taxa and organizational levels. Key topics for further research include a) salinity responses by more taxa, b) responses to especially toxic ions (i.e., potassium, bicarbonate, sulfate, magnesium), c) mechanisms causing positive and unimodal responses, d) traits underpinning responses, e) effects transcending organizational levels, f) ion-specific response thresholds, and g) interactions between salinity and other stressors. Our review suggests inter-taxa variation in sensitivity to salinization reflects occurrence of certain biological traits, including gill-breathing, semi-permeable skin, multiple life stages, and limited mobility. We propose a traits-based framework to predict salinization sensitivity from shared traits. This evolutionary approach could inform management aimed at preventing or reducing adverse impacts of freshwater salinization.

Science of the Total Environment↗
USGS2016

Application of a hybrid model to reduce bias and improve precision in population estimates for elk (Cervus elaphus) inhabiting a cold desert ecosystem

Accurately estimating the size of wildlife populations is critical to wildlife management and conservation of species. Raw counts or “minimum counts” are still used as a basis for wildlife management decisions. Uncorrected raw counts are not only negatively biased due to failure to account for undetected animals, but also provide no estimate of precision on which to judge the utility of counts. We applied a hybrid population estimation technique that combined sightability modeling, radio collar-based mark-resight, and simultaneous double count (double-observer) modeling to estimate the population size of elk in a high elevation desert ecosystem. Combining several models maximizes the strengths of each individual model while minimizing their singular weaknesses. We collected data with aerial helicopter surveys of the elk population in the San Luis Valley and adjacent mountains in Colorado State, USA in 2005 and 2007. We present estimates from 7 alternative analyses: 3 based on different methods for obtaining a raw count and 4 based on different statistical models to correct for sighting probability bias. The most reliable of these approaches is a hybrid double-observer sightability model (model M H ), which uses detection patterns of 2 independent observers in a helicopter plus telemetry-based detections of radio collared elk groups. Data were fit to customized mark-resight models with individual sighting covariates. Error estimates were obtained by a bootstrapping procedure. The hybrid method was an improvement over commonly used alternatives, with improved precision compared to sightability modeling and reduced bias compared to double-observer modeling. The resulting population estimate corrected for multiple sources of undercount bias that, if left uncorrected, would have underestimated the true population size by as much as 22.9%. Our comparison of these alternative methods demonstrates how various components of our method contribute to improving the final estimate and demonstrates why each is necessary.

Colorado↗
USGS2022

Categorizing active marine acoustic sources based on their potential to affect marine animals

Marine acoustic sources are widely used for geophysical imaging, oceanographic sensing, and communicating with and tracking objects or robotic vehicles in the water column. Under the U.S. Marine Mammal Protection Act and similar regulations in several other countries, the impact of controlled acoustic sources is assessed based on whether the sound levels received by marine mammals meet the criteria for harassment that causes certain behavioral responses. This study describes quantitative factors beyond received sound levels that could be used to assess how marine species are affected by many commonly deployed marine acoustic sources, including airguns, high-resolution geophysical sources (e.g., multibeam echosounders, sidescan sonars, subbottom profilers, boomers, and sparkers), oceanographic instrumentation (e.g., acoustic doppler current profilers, split-beam fisheries sonars), and communication/tracking sources (e.g., acoustic releases and locators, navigational transponders). Using physical criteria about the sources, such as source level, transmission frequency, directionality, beamwidth, and pulse repetition rate, we divide marine acoustic sources into four tiers that could inform regulatory evaluation. Tier 1 refers to high-energy airgun surveys with a total volume larger than 1500 in 3 (24.5 L) or arrays with more than 12 airguns, while Tier 2 covers the remaining low/intermediate energy airgun surveys. Tier 4 includes most high-resolution geophysical, oceanographic, and communication/tracking sources, which are considered unlikely to result in incidental take of marine mammals and therefore termed de minimis . Tier 3 covers most non-airgun seismic sources, which either have characteristics that do not meet the de minimis category (e.g., some sparkers) or could not be fully evaluated here (e.g., bubble guns, some boomers). We also consider the simultaneous use of multiple acoustic sources, discuss marine mammal field observations that are consistent with the de minimis designation for some acoustic sources, and suggest how to evaluate acoustic sources that are not explicitly considered here.

Journal of Marine Science and Engineering↗
USGS2024

Viral pathogen detection in U.S. game-farm mallard (Anas platyrhynchos) flags spillover risk to wild birds

The threat posed by emerging infectious diseases is a major concern for global public health, animal health and food security, and the role of birds in transmission is increasingly under scrutiny. Each year, millions of mass-reared game-farm birds are released into the wild, presenting a unique and a poorly understood risk to wild and susceptible bird populations, and to human health. In particular, the shedding of enteric pathogens through excrement into bodies of water at shared migratory stop-over sites, and breeding and wintering grounds, could facilitate multi-species long-distance pathogen dispersal and infection of high numbers of naive endemic birds annually. The Mallard ( Anas platyrhynchos ) is the most abundant of all duck species, migratory across much of its range, and an important game species for pen-rearing and release. Major recent population declines along the US Atlantic coast has been attributed to game-farm and wild mallard interbreeding and the introduction maladaptive traits into wild populations. However, pathogen transmission and zoonosis among game-farms Mallard may also impact these populations, as well as wildlife and human health. Here, we screened 16 game-farm Mallard from Wisconsin, United States, for enteric viral pathogens using metatranscriptomic data. Four families of viral pathogens were identified – Picobirnaviridae (Genogroup I), Caliciviridae (Duck Nacovirus ), Picornaviridae (Duck Aalivirus ) and Sedoreoviridae (Duck Rotavirus G). To our knowledge, this is the first report of Aalivirus in the Americas, and the first report of Calicivirus outside domestic chicken and turkey flocks in the United States. Our findings highlight the risk of viral pathogen spillover from peri-domestically reared game birds to naive wild bird populations.

Frontiers Earth Science Journal↗