Waterfowl Wintering Research Articles

Corn Field Management for Wintering Waterfowl on Eastern Long Island, New York

Aim: A novel corn field management program to feed wintering waterfowl was investigated. Background: Decreased food availability for waterfowl on the Atlantic coast may necessitate novel management. Methods: Standing sections of corn were chopped using a brush hog once every two weeks after the close of waterfowl hunting season on Long Island, New York, February – March 2018 and 2019. Corn was sampled to determine initial yield and waterfowl and other wildlife use, corn depletion, and relationships between depletion and energy needs of waterfowl were determined. Results: The mean (± SE) initial yield was 5,156.0 ± 1,306.7 kg/ha. Canada geese accounted for 54% of all waterfowl use and mallards were twice as abundant at corn fields than American black ducks. Fields averaged 4.08 ± 0.20 ha, but ~50% less corn could have been planted to meet the energy needs of waterfowl in this study. However, 27% of sections chopped in the first two weeks were depleted to zero or near zero, whereas sections chopped in the last two weeks had 1,954.9 ± 1,309.9 kg/ha of corn. Conclusion: More corn could have been chopped early in winter and less as spring approached to meet the seasonal energy needs of waterfowl. Waterfowl using corn fields could gain fitness advantages, but a better understanding of diets, body condition, and seasonal stress, as well as the use of corn fields relative to other habitats by individual Canada geese and ducks, are needed. Results provide guidance on the delivery of corn planting and chopping programs to feed wintering waterfowl in the northeastern United States.

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

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

Citizen science reveals waterfowl responses to extreme winter weather.

Global climate change is increasing the frequency and severity of extreme climatic events (ECEs) which may be especially detrimental during late‐winter when many species are surviving on scarce resources. However, monitoring animal populations relative to ECEs is logistically challenging. Crowd‐sourced datasets may provide opportunity to monitor species' responses to short‐term chance phenomena such as ECEs. We used 14 years of eBird—a global citizen science initiative—to examine distribution changes for seven wintering waterfowl species across North America in response to recent extreme winter polar vortex disruptions. To validate inferences from eBird, we compared eBird distribution changes against locational data from 362 GPS‐tagged Mallards (Anas platyrhynchos) in the Mississippi Flyway. Distributional shifts between eBird and GPS‐tagged Mallards were similar following an ECE in February 2021. In general, the ECE affected continental waterfowl population distributions; however, responses were variable across species and flyways. Waterfowl distributions tended to stay near wintering latitudes or moved north at lesser distances compared with non‐ECE years, suggesting preparedness for spring migration was a stronger “pull” than extreme weather was a “push” pressure. Surprisingly, larger‐bodied waterfowl with grubbing foraging strategies (i.e., geese) delayed their northward range shift during ECE years, whereas smaller‐bodied ducks were less affected. Lastly, wetland obligate species shifted southward during ECE years. Collectively, these results suggest specialized foraging strategies likely related to resource limitations, but not body size, necessitate movement from extreme late‐winter weather in waterfowl. Our results demonstrate eBird's potential to monitor population‐level effects of weather events, especially severe ECEs. eBird and other crowd‐sourced datasets can be valuable to identify species which are adaptable or vulnerable to ECEs and thus, begin to inform conservation policy and management to combat negative effects of global climate change.

Factors affecting waterfowl hunting and harvest at the Evros delta, Greece

The Evros delta is one of the most important wetlands for wintering waterfowl in Greece and the most popular among waterfowl hunters. This study addresses hunting activity and harvest while also investigating the relationship between weather conditions and hunting activity to suggest ways of improving waterfowl management. We counted wintering waterfowl and hunter numbers, and conducted hunter bag surveys during December–February over four hunting seasons. We calculated a 10-day goose and duck Preferential Shooting Index (PSI), which is the ratio of observed number of shot birds to the number of birds expected to have been shot if the birds were shot in proportion to their availability. Common Teal, Mallard and Greater White-fronted Goose were the most abundant species both in the field and in hunter bags. The mean number of hunters/day was 99.9, with each one shooting on average 2.5 birds/day. The overall waterfowl harvested accounted for 1.3% of the total waterfowl population. For geese this proportion was six times higher (8.7%), while for ducks alone and protected species was 1.2% and 1.4% respectively. Geese were shot more often than expected (PSI 6.55), while ducks and protected species were shot according to their availability (PSI 0.86 and 1.02, respectively). Wind speed, precipitation and geese number in the field were the best predictors of overall harvest and number of hunters. To reduce goose overshooting and the probability of protected species being accidentally shot, we suggest habitat management actions for the geese feeding areas and hunters’ awareness raising.

Waterfowl Wintering in Moscow (1985–1999): Dependence on Air Temperatures and the Prosperity of the Human Population

Abstract. Over fifteen years (1985–1999) waterfowl were counted during one day in January on 33 permanent routes with a total length of c. 310 km along the banks of all rivers and ponds throughout the city. 23 species (apart from gulls) were recorded. The number of species varied from 3 to 10 in different years and increased significantly during the study period. Mallard Anas platyrhynchos was the most numerous species (98–99% of individuals). The proportion of male Mallards varied from year to year within the range 54–63%. The number of Mallards gradually increased from c. 17 300 in the winter of 1984–1985 to c. 28 000 in the winter of 1989–90 but then declined to c. 7500 in the winter of 1997–1998. These changes appear to depend on both air temperatures during the winter and the prosperity of the city's inhabitants, who feed ducks with bread and scraps of food. It is highly probable that the change in the socio-economic situation has been the main cause of the decline in waterfowl observed during the 1990s.

Hydrological Condition Constrains Vegetation Dynamics for Wintering Waterfowl in China’s East Dongting Lake Wetland

As an internationally important wintering region for waterfowls on the East Asian–Australasian Flyway, the national reserve of China’s East Dongting Lake wetland is abundant in animal and plant resources during winter. The hydrological regimes, as well as vegetation dynamics, in the wetland have experienced substantial changes due to global climate change and anthropogenic disturbances, such as the construction of hydroelectric dams. However, few studies have investigated how the wetland vegetation has changed over time, particularly during the wintering season, and how this has directly affected habitat suitability for migratory waterfowl. Thus, it is necessary to monitor the spatio-temporal dynamics of vegetation in the protected wetland and explore the potential factors that alter it. In this study, the data set of time-series Moderate Resolution Imaging Spectroradiometer (MODIS) normalized difference vegetation index (NDVI) from 2000 to 2018 was used to analyze the seasonal dynamics and interannual trends of vegetation over the wintering period from October to January. The results showed that the average NDVI exhibited an overall increasing trend, with the trend rising slowly in recent years. The largest monthly mean NDVI generally occurred in November, which is pertinent to the quantity of wintering waterfowl in the East Dongting Lake wetland. Meanwhile, the mean NDVI in the wintering season is significantly correlated to temperature and water area, with apparent lagging effects. Long-term stability analysis presented a gradually decreasing pattern from the central body of water to the surrounding area. All analyses will help the government to make appropriate management strategies to protect the habitat of wintering waterfowl in the wetland.

DNA Sequencing Confirms Tundra Bean Goose (Anser serrirostris serrirostris) Occurrence in the Mississippi Alluvial Valley in Arkansas, USA

First sighting records of rare occurrences may become increasingly important for recognizing changes in distribution, changes in migratory strategies, or increases in hybridization. We documented the first record of a Tundra Bean Goose in the Mississippi Alluvial Valley, the outlet and historic floodplain for much of North America and one of the most important waterfowl wintering areas on the continent. We also document the first genetically confirmed record in the contiguous USA. Bean Goose (Anser fabalis and A. serrirostris) occurrences in North America are rare, especially outside of Alaska. On 24 January 2018, a Tundra Bean Goose (A. s. serrirostris) was harvested by a hunter in a winter-flooded rice field in Desha County, Arkansas, USA, near Dumas. The goose was mixed with a flock of 50 Greater White-Fronted Geese (A. albifrons). Because this individual was legally, albeit accidentally shot, we had the rare and exciting opportunity to obtain morphometric measurements and biological samples. As a result, we were able to verify the species and subspecies through genetic and morphological analysis. We determined the goose was an adult female Tundra Bean Goose, and mitochondrial DNA control region sequence data indicated this specimen was the subspecies A. s. serrirostris.

Behavioural responses of the whooper swansCygnus cygnusto human disturbance and their adaptability to the different habitats in the Rongcheng lagoon of China

AbstractWith urbanization influences and economic development, the area and integrity of coastal wetlands are suffering destruction in China, which would affect waterfowl wintering. The Rongcheng Lake is an important wintering ground for migratory birds in Central Asia, especially for whooper swansCygnus cygnus. In this study, we investigated the numbers and behaviours of the whooper swans in the different habitats of the Swan Lake from November in 2015 to April in 2016, collected 72 water samples in the estuaries, and carried out food addition experiments in order to analyse the behavioural responses and adaptability of the whooper swans to the changing environment. Our results showed that the dominant behaviour of the whooper swans was resting, followed by feeding and locomotion and the whooper swans mainly distributed in the beach, estuary, and lagoon. Moreover, their distributions were affected by fresh water and food availability, whereas the human disturbance played an important role in their distributions and behavioural variations. To adapt to the changing environment, different wintering strategies were adopted by the whooper swans during the different overwintering period. The estuary protection and human feeding were very vital tools to help the whooper swans adjust their body to prepare for migrating next year.

Spring migration patterns, habitat use, and stopover site protection status for two declining waterfowl species wintering in China as revealed by satellite tracking.

East Asian migratory waterfowl have greatly declined since the 1950s, especially the populations that winter in China. Conservation is severely hampered by the lack of primary information about migration patterns and stopover sites. This study utilizes satellite tracking techniques and advanced spatial analyses to investigate spring migration of the greater white‐fronted goose (Anser albifrons) and tundra bean goose (Anser serrirostris) wintering along the Yangtze River Floodplain. Based on 24 tracks obtained from 21 individuals during the spring of 2015 and 2016, we found that the Northeast China Plain is far‐out the most intensively used stopover site during migration, with geese staying for over 1 month. This region has also been intensely developed for agriculture, suggesting a causal link to the decline in East Asian waterfowl wintering in China. The protection of waterbodies used as roosting area, especially those surrounded by intensive foraging land, is critical for waterfowl survival. Over 90% of the core area used during spring migration is not protected. We suggest that future ground surveys should target these areas to confirm their relevance for migratory waterfowl at the population level, and core roosting area at critical spring‐staging sites should be integrated in the network of protected areas along the flyway. Moreover, the potential bird–human conflict in core stopover area needs to be further studied. Our study illustrates how satellite tracking combined with spatial analyses can provide crucial insights necessary to improve the conservation of declining Migratory species.

Species distribution modeling in regions of high need and limited data: waterfowl of China

BackgroundA number of conservation and societal issues require understanding how species are distributed on the landscape, yet ecologists are often faced with a lack of data to develop models at the resolution and extent desired, resulting in inefficient use of conservation resources. Such a situation presented itself in our attempt to develop waterfowl distribution models as part of a multi-disciplinary team targeting the control of the highly pathogenic H5N1 avian influenza virus in China.MethodsFaced with limited data, we built species distribution models using a habitat suitability approach for China’s breeding and non-breeding (hereafter, wintering) waterfowl. An extensive review of the literature was used to determine model parameters for habitat modeling. Habitat relationships were implemented in GIS using land cover covariates. Wintering models were validated using waterfowl census data, while breeding models, though developed for many species, were only validated for the one species with sufficient telemetry data available.ResultsWe developed suitability models for 42 waterfowl species (30 breeding and 39 wintering) at 1 km resolution for the extent of China, along with cumulative and genus level species richness maps. Breeding season models showed highest waterfowl suitability in wetlands of the high-elevation west-central plateau and northeastern China. Wintering waterfowl suitability was highest in the lowland regions of southeastern China. Validation measures indicated strong performance in predicting species presence. Comparing our model outputs to China’s protected areas indicated that breeding habitat was generally better covered than wintering habitat, and identified locations for which additional research and protection should be prioritized.ConclusionsThese suitability models are the first available for many of China’s waterfowl species, and have direct utility to conservation and habitat planning and prioritizing management of critically important areas, providing an example of how this approach may aid others faced with the challenge of addressing conservation issues with little data to inform decision making.

An aerial grid‐based sampling method to estimate nonbreeding duck abundance

ABSTRACTProbability‐based sampling designs for aerial surveys are useful for estimating wintering waterfowl abundances in large areas with contiguous habitat (e.g., Mississippi Alluvial Valley). The effectiveness of these approaches for estimating abundance of nonbreeding waterfowl in small areas with discontinuous habitat has rarely been assessed. Surveys conducted within riverine areas introduce sampling design difficulties because of discontinuous bottomland habitat and irregularity of flooding events. Therefore, we implemented and evaluated a generalizable grid‐based, stratified random sampling design to estimate weekly duck abundance within the Wabash River floodplain in southeastern Illinois and southwestern Indiana, USA, during midwinter and early spring 2012 and 2013. We used aerial and ground‐based counts to generate abundance estimates and evaluate within‐week variation of counts. Peak duck abundance totaled 279,717 (SE = 69,101) in 2012 and 742,027 (SE = 296,563) in 2013. Dabbling ducks were the most abundant duck guild detected and abundance estimates for this group met our precision goal (CV ≤ 0.25) in 4 of 18 surveys ( = 0.33, range = 0.20–0.51). We compared the grid‐based approach with a traditional aerial inventory and found that estimates from the grid‐based approach were on average 75,175 (SE = 46,768) greater than inventory counts. Desired levels of precision were often not met, yet design improvements in 2013 notably increased precision, suggesting that further modifications may allow this method to be useful in riverine areas with discontinuous and ephemeral habitat. © 2017 The Wildlife Society.

Mercury in wintering American black ducks (Anas rubripes) downstream from a point-source on the lower Penobscot River, Maine, USA

Waterfowl wintering along the lower Penobscot River, Maine continue to be exposed to elevated Hg concentrations from the HoltraChem chlor-alkali plant that operated along the river between 1967 and 2000. In American black ducks (Anas rubripes) total Hg in duck breast muscle increased with residence time on contaminated marshes, reaching means of 0.82±0.21μg/g ww (wet weight) by the end of the fall hunting season, and prompting Maine to issue a human consumption advisory on duck breast muscle. Methyl Hg comprised over 99% of the total Hg in breast muscle. The ratio of Hg concentrations in blood and muscle were strongly correlated and approached 1:1 after extended residence times. Primary feather (P1) total Hg concentrations averaged 2.2±1.3μg/g fw (fresh weight), verifying low Hg exposure during feather growth on distant breeding grounds the preceding summer. Mercury concentrations in black ducks, following winter residence along the lower Penobscot exceeded levels associated with reproductive toxicity. Carry-over of Hg to summer breeding grounds may limit the subsequent reproductive success of black ducks.

Maintenance of influenza A viruses and antibody response in mallards (Anas platyrhynchos) sampled during the non-breeding season in Alaska.

Prevalence of influenza A virus (IAV) infections in northern-breeding waterfowl has previously been reported to reach an annual peak during late summer or autumn; however, little is known about IAV infection dynamics in waterfowl populations persisting at high-latitude regions such as Alaska, during winter. We captured mallards (Anas platyrhynchos) throughout the non-breeding season (August–April) of 2012–2015 in Fairbanks and Anchorage, the two largest cities in Alaska, to assess patterns of IAV infection and antibody production using molecular methods and a standard serologic assay. In addition, we used virus isolation, genetic sequencing, and a virus microneutralization assay to characterize viral subtypes and to evaluate the immune response of mallards captured on multiple occasions through time. We captured 923 mallards during three successive sampling years: Fairbanks in 2012/13 and 2013/14, and Anchorage in 2014/15. Prevalence varied by age, season, and year/site with high and relatively stable estimates throughout the non-breeding season. Infected birds were detected in all locations/seasons except early-winter in Fairbanks during 2013/14. IAVs with 17 combinations of hemagglutinin (H1–5, H7–9, H11, H12) and neuraminidase (N1–6, N8, N9) subtypes were isolated. Antibodies to IAVs were detected throughout autumn and winter for all sampling locations and years, however, seroprevalence was higher among adults and varied among years. Mallards exhibited individual heterogeneity with regard to immune response, providing instances of both seroconversion and seroreversion to detected viral subtypes. The probability that an individual transitioned from one serostatus to another varied by age, with juvenile mallards having higher rates of seroconversion and seroreversion than adults. Our study provides evidence that a diversity of IAVs circulate in populations of mallards wintering at urban locations in Alaska, and we suggest waterfowl wintering at high-latitudes may play an important role in maintenance of viruses across breeding seasons.

Bird Species at Risk in California’s Central Valley: A Framework for Setting Conservation Objectives

Author(s): Shuford, W. David; Hertel, Meghan | Abstract: http://escholarship.org/uc/item/63j6s1tb Populations of many species of birds are declining worldwide from habitat loss and degradation and the effects of contamination, disease, and alien species. Effects have been great in California’s Central Valley from the loss of over 90% of its historical wetland and riparian habitats. Conservation initiatives at various geographic scales have ranged from protecting and restoring habitats or ecosystems for broad suites of species to ones identifying individual declining and vulnerable taxa and spurring actions to halt or reverse their population declines. In taking the first approach, the Central Valley Joint Venture initially focused on restoring habitats and populations of wintering and breeding waterfowl but currently promotes the conservation of all birds. This joint venture is setting population and habitat objectives for seven taxonomic or habitat bird groups, but to date little attention has been paid to at-risk species of particular conservation concern. We identified 38 at-risk species, subspecies, or distinct populations of birds that warrant heightened conservation efforts in the Central Valley. At-risk birds are unevenly distributed among subregions and habitat types in this valley, but most face the primary threat of habitat loss and degradation. The treatment of at-risk species varies greatly among the seven bird groups considered by the joint venture, and, overall, conservation objectives are not addressed specifically for 50% of the region’s at-risk taxa, though some surely benefit from objectives set for other groups. To adequately treat at-risk species, we recommend a framework for setting conservation objectives that evaluates assumptions about limiting factors, considers objectives already set for threatened and endangered species, assesses whether objectives set for other groups or focal species meet the needs of at-risk species lacking such objectives, establishes objectives for at-risk species for habitats or seasons not currently considered, and highlights information gaps to be filled to effectively set new or refined objectives.

Heavy Metals in Liver and Brain of Waterfowl from the Evros Delta, Greece.

The concentrations of six heavy metals (cadmium [Cd], chromium [Cr], copper [Cu], manganese [Mn], lead [Pb], and zinc [Zn]) were determined in liver and brain of nine species of waterfowl from the Evros Delta, one of the most important wetlands in Greece, to assess metal contamination and potential risk to waterfowl. Significant differences among species were found for hepatic Cr, Cu, Pb, and Zn; the highest levels of all metals were found in liver of mute swans. Cd increased significantly with age in both organs of wigeon; some differences were also observed between males and females of the same species. Feeding habits were found to significantly affect hepatic Cr, Zn, and Cu concentrations with greater concentrations found in herbivorous than omnivorous species. Several significant positive correlations between metals were detected mainly in liver samples, which were attributable either to their association to metallothioneins or to common routes of exposure of waterfowl. Hepatic and cerebral concentrations of Cd and Pb correlated positively. Given the discrepancies in the thresholds or critical levels of metals in tissues of waterfowl, our survey showed that environmental exposure to increased levels of heavy metals may threaten, at least to some degree, the populations of waterfowl wintering in the Evros Delta. In a small percentage of birds, values indicative of severe adverse effects were determined. Swans that had been found dead showed some of the highest values, whereas accumulation levels did not follow a consistent pattern among the ducks examined.

Potential Effects of Drought on Carrying Capacity for Wintering Waterfowl in the Central Valley of California

AbstractWe used the bioenergetics model TRUEMET to evaluate potential effects of California's recent drought on food supplies for waterfowl wintering in the Central Valley under a range of habitat and waterfowl population scenarios. In nondrought years in the current Central Valley landscape, food supplies are projected to be adequate for waterfowl from fall through early spring (except late March) even if waterfowl populations reach North American Waterfowl Management Plan goals. However, in all drought scenarios that we evaluated, food supplies were projected to be exhausted for ducks by mid- to late winter and by late winter or early spring for geese. For ducks, these results were strongly related to projected declines in winter-flooded rice fields that provide 45% of all the food energy available to ducks in the Central Valley in nondrought water years. Delayed flooding of some managed wetlands may help alleviate food shortages by providing wetland food resources better timed with waterfowl migration and abundance patterns in the Central Valley, as well as reducing the amount of water needed to manage these habitats. However, future research is needed to evaluate the impacts of delayed flooding on waterfowl hunting, and whether California's existing water delivery system would make delayed flooding feasible. Securing adequate water supplies for waterfowl and other wetland-dependent birds is among the greatest challenges facing resource managers in coming years, especially in the increasingly arid western United States.

Developing a wintering waterfowl community baseline for environmental monitoring of Narragansett Bay, Rhode Island

In 2004, the Atlantic Ecology Division of the US Environmental Protection Agency’s Office of Research and Development began an annual winter waterfowl survey of Rhode Island’s Narragansett Bay. Herein, we explore the survey data gathered from 2004 to 2011 in order to establish a benchmark understanding of our waterfowl communities and to establish a statistical framework for future environmental monitoring. The abundance and diversity of wintering waterfowl were relatively stable during the initial years of this survey, except in 2010 when there was a large spike in abundance and a reciprocal fall in diversity. There was no significant change in ranked abundance of most waterfowl species, with only Bufflehead (Bucephala albeola) and Hooded Merganser (Lophodytes cucllatus) showing a slight yet significant upward trend during the course of our survey period. Nonmetric multidimensional scaling (NMDS) was used to examine the community structure of wintering waterfowl. The results of the NMDS indicate that there is a spatial structure to the waterfowl communities of Narragansett Bay and this structure has remained relatively stable since the survey began. Our NMDS analysis helps to solidify what is known anecdotally about the bay’s waterfowl ecology, and provides a formalized benchmark for long-term monitoring of Narragansett Bay’s waterfowl communities. Birds, including waterfowl, are preferred bioindicators and we propose using our multivariate approach to monitor the future health of the bay. While this research focuses on a specific area of New England, these methods can be easily applied to novel areas of concern and provide a straightforward nonparametric approach to community-level monitoring. The methods provide a statistic test to examine potential drivers of community turnover and well-suited visualization tools.

Developing a wintering waterfowl community baseline for environmental monitoring of Narragansett Bay, Rhode Island

In 2004, the Atlantic Ecology Division of the US Environmental Protection Agency’s Office of Research and Development began an annual winter waterfowl survey of Rhode Island’s Narragansett Bay. Herein, we explore the survey data gathered from 2004 to 2011 in order to establish a benchmark understanding of our waterfowl communities and to establish a statistical framework for future environmental monitoring. The abundance and diversity of wintering waterfowl were relatively stable during the initial years of this survey, except in 2010 when there was a large spike in abundance and a reciprocal fall in diversity. There was no significant change in ranked abundance of most waterfowl species, with only Bufflehead ( Bucephala albeola) and Hooded Merganser ( Lophodytes cucllatus) showing a slight yet significant upward trend during the course of our survey period. Nonmetric multidimensional scaling (NMDS) was used to examine the community structure of wintering waterfowl. The results of the NMDS indicate that there is a spatial structure to the waterfowl communities of Narragansett Bay and this structure has remained relatively stable since the survey began. Our NMDS analysis helps to solidify what is known anecdotally about the bay’s waterfowl ecology, and provides a formalized benchmark for long-term monitoring of Narragansett Bay’s waterfowl communities. Birds, including waterfowl, are preferred bioindicators and we propose using our multivariate approach to monitor the future health of the bay. While this research focuses on a specific area of New England, these methods can be easily applied to novel areas of concern and provide a straightforward nonparametric approach to community-level monitoring. The methods provide a statistic test to examine potential drivers of community turnover and well-suited visualization tools.

Developing a wintering waterfowl community baseline for environmental monitoring of Narragansett Bay, Rhode Island.

In 2004, the Atlantic Ecology Division of the US Environmental Protection Agency's Office of Research and Development began an annual winter waterfowl survey of Rhode Island's Narragansett Bay. Herein, we explore the survey data gathered from 2004 to 2011 in order to establish a benchmark understanding of our waterfowl communities and to establish a statistical framework for future environmental monitoring. The abundance and diversity of wintering waterfowl were relatively stable during the initial years of this survey, except in 2010 when there was a large spike in abundance and a reciprocal fall in diversity. There was no significant change in ranked abundance of most waterfowl species, with only Bufflehead ( Bucephala albeola) and Hooded Merganser ( Lophodytes cucllatus) showing a slight yet significant upward trend during the course of our survey period. Nonmetric multidimensional scaling (NMDS) was used to examine the community structure of wintering waterfowl. The results of the NMDS indicate that there is a spatial structure to the waterfowl communities of Narragansett Bay and this structure has remained relatively stable since the survey began. Our NMDS analysis helps to solidify what is known anecdotally about the bay's waterfowl ecology, and provides a formalized benchmark for long-term monitoring of Narragansett Bay's waterfowl communities. Birds, including waterfowl, are preferred bioindicators and we propose using our multivariate approach to monitor the future health of the bay. While this research focuses on a specific area of New England, these methods can be easily applied to novel areas of concern and provide a straightforward nonparametric approach to community-level monitoring. The methods provide a statistic test to examine potential drivers of community turnover and well-suited visualization tools.

Effects of habitat conditions in created wetlands on sustaining wintering waterfowl in riverine plains, Nakdong River, South Korea

The landscape setting of a habitat strongly influences the distribution, abundance, and species composition of waterfowl. Thus, habitat assessment is very important to understand the habitat characteristics that sustain waterfowl assemblages. In this study, we hypothesized that the excessive use of artificial materials when new wetlands are constructed nega tively influences wintering waterfowl. To test this hypothesis, we measured environmental factors, assessed habitat, and investigated waterfowl at 13 artificial wetlands in the Nakdong River Basin. There were greater numbers of waterfowl species and individuals in artificial wetlands with high habitat assessment scores. In contrast, environmental factors did not affect waterfowl distribution. In particular, features of natural habitats, such as macrophytes and sandbars, and the surrounding land-use patterns were important factors for sustaining waterfowl assemblages in each created wetland. Our results show that promoting naturalness in wetlands and surrounding areas would increase the species diversity and abundance of waterfowl. Further, complex habitats, such as wetlands and some terrestrial habitats, support both aquatic and terrestrial species because mixed habitats feature a larger array of food sources than more limited habitats do.