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USGS2025

Trait-based selection of seeds ingested and dispersed by North American waterfowl

There are few studies on the extent to which waterfowl select plant food compared with what is available in wetland ecosystems. We used a new dataset on the presence of seeds in the alimentary canal or feces to identify flowering plant species whose seeds are ingested by North American ducks or geese. These data are a proxy for dispersal interactions because an important fraction of ingested seeds survives gut passage and is dispersed by endozoochory. We compared the plant traits of species whose seeds were ingested with those of species on the U.S. Department of Agriculture National Wetland Plants List (NWPL). Using a global dataset on plant form and function and chi-squared tests, we compared four categorical traits (moisture requirements, growth form, plant height, and seed mass) between species whose seeds are ingested by North American ducks and geese with the NWPL. Our analyses identified significant differences between the trait distributions of plants whose seeds were ingested by waterfowl guilds and those of the NWPL. Geese and ducks (except whistling ducks) ingested more aquatic and semiaquatic plant species than expected from the NWPL. All guilds except sea ducks ingested more herbaceous graminoids and fewer shrubs or trees than expected. Diving ducks interacted with fewer of the taller plants (>5 m) than expected, but otherwise plant height distributions did not differ from those expected. All waterfowl guilds ingested more species of intermediate seed size (1–10 mg) and fewer species of the smallest (<0.1 mg) or largest (>100 mg) size categories than expected. These results help to explain the role of the long-distance dispersal of seeds by migratory waterfowl in plant biogeography and how plant distributions are likely to respond to global change.

North America↗

USGS2021

Assessment of cereal grain waste densities to aid waterfowl conservation planning in the Klamath Basin

Postharvest waste seed from cereal grains is a major dietary component of waterfowl in the Klamath Basin in northeastern California and southeastern Oregon, a region that plays host to over a million waterfowl annually. Understanding food abundance is critical to local waterfowl management; therefore, we conducted a study in 2008 to investigate waste grain densities in barley, oat, and wheat fields. We used hierarchal mixed effect models to assess several factors that may affect waste grain densities postharvest. We also compared the effects of residue management practices to measure the effect of these treatments. To understand the scope of postharvest practices, we conducted a weekly road survey to document treatments applied to fields in our study area. We found that region best explained the variance of postharvest waste grain in barley fields, where the Tule Lake region had 89% greater densities than Lower Klamath. Neither harvester age nor baling affected waste grain in oats fields. In wheat fields, the model containing region and lodging ranked highest, where the Tule Lake region had 66% greater waste densities than Lower Klamath, and lodging increased waste grain by 70%. Burning did not reduce waste grain in barley or oat fields. Chisel-disking reduced waste grain by 94% in wheat fields compared with postharvest. Our field treatment survey found that 70% of barley fields were untreated while 18% were disked and 13% were burned and flooded. We estimated that 82% of oat fields were burned postharvest, while 18% were burned and flooded. In wheat, 61% of fields were left untreated, while 16% were disked, 8% were chisel-plowed, and 7% were flooded postharvest. Flooding and burning occurred primarily on National Wildlife Refuges, while disking, chisel-plowing, and postharvest irrigation occurred solely on private properties. Our results indicate that reducing tillage treatments would boost accessibility of cereal grain food resources to waterfowl in the Klamath Basin, and incentives to flood grain fields on private properties should be considered for the same purpose when and where possible.

California, Oregon↗

USGS1993

Increasing waterfowl nesting success on islands and peninsulas

Waterfowl that nest in uplands in the prairie pothole region have had low recruitment rates in recent decades, primarily because of predation. The loss of breeding waterfowl and their progeny has generated interest in management techniques that safeguard incubating hens and their eggs. Developing islands and peninsulas for nesting waterfowl has potential because these sites are naturally attractive to breeding ducks and geese. In fact, dense nesting colonies of ducks developed on some islands when successful females and a portion of their female progeny returned in subsequent years. Managers have successfully duplicated the beneficial attributes of islands by developing various nesting habitats that are protected by water barriers. This chapter addresses the management of existing islands, the creation of new islands, and the modification of peninsulas into islands to increase nesting success in waterfowl.

Fish and Wildlife Leaflet↗

USGS1988

Key to acanthocephala reported in waterfowl

This is the third part of a continuing series on helminths reported in waterfowl (McDonald 1974, 1981). Coots and moorhens (in Family Rallidae, Order Gruiformes) are included with the Anatidae of Anseriformes. The goal of these studies i complete coverage of waterfowl helminths of the world, although the original incentive-inadequate knowledge of the parasites of North American waterfowl- is less true now. World coverage is desirable because the world distribution of the family, tribes, and even many species of waterfowl often results in world distribution of parasites.

Resource Publication↗

USGS2000

Comparison of helicopter and ground surveys of waterfowl broods in southern Ontario

Managers often employ aerial survey information to manage waterfowl. Results of surveys by helicopter and from elevated platforms were compared to determine the accuracy of helicopters to detect waterfowl broods on beaver ponds in southern Ontario in 1996 and 1997. Fewer broods were detected from the helicopter than by observers in elevated platforms at wetland margins. When broods were detected by helicopter crews, >90% were correctly enumerated and >80% were correctly aged. A second helicopter survey, the day following the first survey, did not change the Visibility Correction Factor (VCF) substantially (1.79 vs. 1.53). Data from the 2 helicopter surveys combined (without ground counts) resulted in greater VCFs (2.17) than when a single helicopter survey and ground count was used (VCF = 1.79). In general, VCFs for most waterfowl broods were lower in forested or closed (emergent and scrub-shrub) wetland habitats than on open wetlands. When multiple broods were present on a wetland, sightability of the additional broods (second, third, etc.) was lower for the helicopter crew than ground crew. Surveys by helicopter are likely most useful to develop indices for waterfowl broods of diver species in large inaccessible areas. If accurate information is required on dabbler brood densities, age, and number of ducklings, quiet observation by crews in elevated platforms should be used.

Ontario↗

USGS2006

Waste rice for waterfowl in the Mississippi Alluvial Valley

Flooded rice fields are important foraging habitats for waterfowl in the lower Mississippi Alluvial Valley (MAV). Waste rice previously was abundant in late autumn (140?492 kg/ha), but early planting and harvest dates in recent years may have increased losses of waste rice during autumn before waterfowl arrive. Research in Mississippi rice fields revealed waste-rice abundance decreased 79?99% during autumns 1995?1996. To determine if this trend existed throughout the MAV, we used multistage sampling (MSS) to estimate waste-rice abundance during September?December 2000?2002. Averaged over years, mean abundance of waste rice decreased 71% between harvest ((x) over bar = 271.0 kg/ha, CV = 13% n = 3 years) and late autumn ( (x) over bar = 78.4 kg/ha, CV = 15% n = 3). Among 15 models formulated to explain variation in rice abundance among fields and across years, the best model indicated abundance of waste rice in late autumn differed between harvester types (i.e., conventional > stripper header) and was positively related to initial waste-rice abundance after harvest. Because abundance of waste rice in late autumn was less than previous estimates in all 3 years, we concluded that waterfowl conservationists have overestimated carrying capacity of rice fields for wintering waterfowl by 52?83% and recommend 325 duck-use days/ha (DUDs) as a revised estimate. We suggest monitoring advances in rice harvest dates to determine when new surveys are warranted and recommend increased management of moist-soil wetlands to compensate for decreased rice abundance.

Journal of Wildlife Management↗

USGS2006

The need for coherence between waterfowl harvest and habitat management

Two of the most significant management efforts affecting waterfowl populations in North America are the North American Waterfowl Management Plan (the Plan) and Federal harvest management programs. Both the Plan and harvest management are continental in scope, involve an extensive group of stakeholders, and rely on adaptive processes of biological planning, implementation, and evaluation. The development of these programs has occurred independently, however, and there has been little explicit recognition that both harvest and habitat effects should be considered for coherent management planning and evaluation. For example, the harvest strategy can affect whether population objectives of the Plan are met, irrespective of the success of the Plan's habitat conservation efforts. Conversely, habitat conservation activities under the Plan can influence harvest potential and, therefore, the amount of hunting opportunity provided. It seems increasingly clear that the Plan's waterfowl population objectives can only be useful for conservation planning and evaluation if they are accompanied by an explicit specification of the harvest strategy and environmental conditions under which they are to be achieved. This clarification also is necessary to ensure that Plan population objectives are not attained solely through the reduction of hunting opportunity. We believe then that it is imperative that these key waterfowl-management programs work to harmonize their objectives. Harvest management programs and the Plan ought to be working toward the same ends, but that is not possible so long as the mutually reinforcing relationship of these programs is obscured by ambiguities in their management objectives.

Wildlife Society Bulletin↗

USGS2010

Changes in the status of harvested rice fields in the Sacramento Valley, California: Implications for wintering waterfowl.

Harvested rice fields provide critical foraging habitat for wintering waterfowl in North America, but their value depends upon post-harvest treatments. We visited harvested ricefields in the Sacramento Valley, California, during the winters of 2007 and 2008 (recent period) and recorded their observed status as harvested (standing or mechanically modified stubble), burned, plowed, or flooded. We compared these data with those from identical studies conducted during the 1980s (early period). We documented substantial changes in field status between periods. First, the area of flooded rice increased 4-5-fold, from about 15% to >40% of fields, because of a 3-4-fold increase in the percentage of fields flooded coupled with a 37-41% increase in the area of rice produced. Concurrently, the area of plowed fields increased from <22% to >35% of fields, burned fields declined from about 40% to 1%, and fields categorized as harvested declined from 22-54% to <15%. The increased flooding has likely increased access to food resources for wintering waterfowl, but this benefit may not be available to some goose species, and may be at least partially countered by the increase of plowed fields, especially those left dry, and the decrease of fields left as harvested.We encourage waterfowl managers to implement a rice field status survey in the Sacramento Valley and other North American rice growing regions as appropriate to support long-term monitoring programs and wetland habitat conservation planning for wintering waterfowl.

California↗

USGS2014

Waterfowl habitat use and selection during the remigial moult period in the northern hemisphere

This paper reviews factors affecting site selection amongst waterfowl (Anatidae) during the flightless remigial moult, emphasising the roles of predation and food supply (especially protein and energy). The current literature suggests survival during flightless moult is at least as high as at other times of the annual cycle, but documented cases of predation of flightless waterfowl under particular conditions lead us to infer that habitat selection is generally highly effective in mitigating or avoiding predation. High energetic costs of feather replacement and specific amino-acid requirements for their construction imply adoption of special energetic and nutritional strategies at a time when flightlessness limits movements. Some waterfowl meet their energy needs from endogenous stores accumulated prior to remigial moult, others rely on exogenous supply, but this varies with species, age, reproductive status and site. Limited evidence suggests feather proteins are derived from endogenous and exogenous sources which may affect site selection. Remigial moult does not occur independently of other annual cycle events and is affected by reproductive investment and success. Hence, moult strategies are affected by age, sex and reproductive history, and may be influenced by the need to attain a certain internal state for the next stage in the annual cycle (e.g. autumn migration). We know little about habitat selection during moult and urge more research of this poorly known part of the annual cycle, with particular emphasis on identifying key concentrations and habitats for specific flyway populations and the effects of disturbance upon these. This knowledge will better inform conservation actions and management actions concerning waterfowl during moult and the habitats that they exploit.

Wildfowl↗

USGS1988

Waterfowl Management Handbook

The North American Waterfowl Management Plan, the Service's most recent mandate for management of migratory waterfowl, and recent legislation such as the Farm Bill all underscore the need for a single source of information about the management of waterfowl and their habitat. Much of this information exists in scientific papers, unpublished reports, or has never been recorded, and thus is not readily accessible by waterfowl managers. A prototype handbook was developed in 1987 and critiqued by 38 reviewers who provided suggestions on style and substance as well as topics for inclusion. The assistance of these reviewers, who included Federal and State wildlife managers, Federal and State biologists, and scientists in the United States and Canada, is most gratefully acknowledged. This product differs from most Fish and Wildlife Leaflets. It will be issued as a series of chapters over the next several years, each with a unique number, designed to be inserted in an accompanying looseleaf binder.

Fish and Wildlife Leaflet↗

USGS2014

Hierarchical model analysis of the Atlantic Flyway Breeding Waterfowl Survey

We used log-linear hierarchical models to analyze data from the Atlantic Flyway Breeding Waterfowl Survey. The survey has been conducted by state biologists each year since 1989 in the northeastern United States from Virginia north to New Hampshire and Vermont. Although yearly population estimates from the survey are used by the United States Fish and Wildlife Service for estimating regional waterfowl population status for mallards (Anas platyrhynchos), black ducks (Anas rubripes), wood ducks (Aix sponsa), and Canada geese (Branta canadensis), they are not routinely adjusted to control for time of day effects and other survey design issues. The hierarchical model analysis permits estimation of year effects and population change while accommodating the repeated sampling of plots and controlling for time of day effects in counting. We compared population estimates from the current stratified random sample analysis to population estimates from hierarchical models with alternative model structures that describe year to year changes as random year effects, a trend with random year effects, or year effects modeled as 1-year differences. Patterns of population change from the hierarchical model results generally were similar to the patterns described by stratified random sample estimates, but significant visibility differences occurred between twilight to midday counts in all species. Controlling for the effects of time of day resulted in larger population estimates for all species in the hierarchical model analysis relative to the stratified random sample analysis. The hierarchical models also provided a convenient means of estimating population trend as derived statistics from the analysis. We detected significant declines in mallard and American black ducks and significant increases in wood ducks and Canada geese, a trend that had not been significant for 3 of these 4 species in the prior analysis. We recommend using hierarchical models for analysis of the Atlantic Flyway Breeding Waterfowl Survey.

Journal of Wildlife Management↗

USGS2019

Clarifying how hunt-specific experiences affect satisfaction among more avid and less avid waterfowl hunters

Marketing research methods could enhance understanding of hunter satisfaction, a key metric for state wildlife management agencies. We use three marketing research approaches—revised importance-performance, importance-grid, and penalty-reward-contrast analysis—to examine the determinants of waterfowl hunter satisfaction. These methods have seen limited application in research on hunting and other outdoor recreation activities. Using results from a 2015 mail survey, we examine the implicit and explicit motivations and overall satisfaction of Minnesota waterfowl hunters. We also differentiate how experiences relate to satisfaction for more avid and less avid hunters, differentiated by self-reported importance of the activity. Seeing ducks in the field was important to satisfaction for both avidity groups. Bagging ducks each day in the field was more important to satisfaction for less avid hunters, while bagging a lot of ducks over the season and attracting ducks with decoys were more important to the satisfaction of more avid hunters. The methods that we employ here illuminate differences between explicit and implicit motivations for participation in waterfowl hunting, clarify factors crucial to satisfaction, and identify asymmetric influences of experiences on satisfaction and dissatisfaction.

Minnesota↗

USGS1998

Waterfowl management on grass-sage stock ponds

We studied waterfowl use of grass-sage stock ponds in north-central Wyoming during the 1988 and 1989 breeding seasons. Dabbling ducks, particularly mallards, were the most common breeders. Indicated breeding pair density averaged 2.7 pairs/ha of wetland surface, while brood density averaged 1.0 brood/ha of wetland surface. Waterfowl use and productivity were greatest on large (> 3 ha), clear, deep ponds with grass shorelines and abundant submergent macrophytes. Pair use was positively correlated with water clarity, pond area, and macroinvertebrate diversity. Brood use was related to macroinvertebrate diversity, pond depth, and Shoreline Development Index. We recommend management priority be given to ponds that are deeper than 1 m to provide more water that is clear so macrophytes can be established. Macroivertebrates should be artificially introduced into ponds. Fencing should be used to improve ponds for waterfowl use and brood rearing.

Wyoming↗

USGS2018

Are waterfowl food resources limited during spring migration? A bioenergetic assessment of playas in Nebraska's rainwater basin

Accurate bioenergetic carrying capacity estimates of wetlands on public and private lands, as well as those managed for crop production are important for managing waterfowl populations and habitats. Given the importance of wetlands in the Rainwater Basin region of Nebraska for spring migrating waterfowl, we quantified and compared seed and aquatic invertebrate biomass and true metabolizable energy (TME) at three wetland types; public wetlands, wetlands enrolled in the Wetlands Reserve Program (WRP), and cropped wetlands. Median seed biomass estimates at public, WRP, and cropped wetlands were 593kg/ha, 561kg/ha, and 419kg/ha respectively. Cumulative TME varied among wetland type, with greater TME at cropped wetlands (2,431kcal/kg) than public (1,740kcal/kg) and WRP wetlands (1,781kcal/kg). Seed biomass estimates from this study were statistically greater than those currently used for management planning in the RWB, however, TME estimates were statistically lower than estimates currently assumed for WRP and public wetlands. Our estimates for aquatic invertebrate biomass were approximately 40-fold less than seed biomass estimates. Based on spring ponding frequency at wetlands in Nebraska’s Rainwater Basin, and the caloric estimates derived for each wetland type, we concluded that the regions wetlands meet the energetic demand of spring migrating waterfowl during 10% of years.

Nebraska↗

USGS2012

Assessment of bias in US waterfowl harvest estimates

Context. North American waterfowl managers have long suspected that waterfowl harvest estimates derived from national harvest surveys in the USA are biased high. Survey bias can be evaluated by comparing survey results with like estimates from independent sources. Aims. We used band-recovery data to assess the magnitude of apparent bias in duck and goose harvest estimates, using mallards (Anas platyrhynchos) and Canada geese (Branta canadensis) as representatives of ducks and geese, respectively. Methods. We compared the number of reported mallard and Canada goose band recoveries, adjusted for band reporting rates, with the estimated harvests of banded mallards and Canada geese from the national harvest surveys. Weused the results of those comparisons to develop correction factors that can be applied to annual duck and goose harvest estimates of the national harvest survey. Key results. National harvest survey estimates of banded mallards harvested annually averaged 1.37 times greater than those calculated from band-recovery data, whereas Canada goose harvest estimates averaged 1.50 or 1.63 times greater than comparable band-recovery estimates, depending on the harvest survey methodology used. Conclusions. Duck harvest estimates produced by the national harvest survey from 1971 to 2010 should be reduced by a factor of 0.73 (95% CI = 0.71–0.75) to correct for apparent bias. Survey-specific correction factors of 0.67 (95% CI = 0.65–0.69) and 0.61 (95% CI = 0.59–0.64) should be applied to the goose harvest estimates for 1971–2001 (duck stamp-based survey) and 1999–2010 (HIP-based survey), respectively. Implications. Although this apparent bias likely has not influenced waterfowl harvest management policy in the USA, it does have negative impacts on some applications of harvest estimates, such as indirect estimation of population size. For those types of analyses, we recommend applying the appropriate correction factor to harvest estimates.

Wildlife Research↗

USGS2020

Explaining support for mandatory versus voluntary conservation actions among waterfowlers

Personal conservation behavior and compliance with natural resource regulations are important to wildlife conservation. We examined how waterfowl hunting involvement, motivations, satisfaction, and experience, along with institutional trust and demographics, correlated with support for waterfowl regulations and personal conservation actions. Regulations included zones, splits, and motorized decoys, while conservation behaviors addressed hunter recruitment, along with donations, volunteering, and voting in ways to support wildlife conservation. Results suggested that agency trust was positively related to support for regulations but negatively related to personal conservation behaviors. An increased orientation to harvest waterfowl was negatively related to both support for regulations and conservation behaviors. Education, income, Ducks Unlimited membership, and days hunting were positively related to personal conservation behavior. Results may help managers work cooperatively with hunters and conservation groups to support wildlife conservation.

Human Dimensions of Wildlife↗

USGS2024

Estimating species-specific U.S. waterfowl harvest

The U.S. Fish and Wildlife Service monitors species-specific waterfowl (ducks, seaducks, geese, and brant) harvest through two hunter surveys, one that estimates the total harvest for each waterfowl group, and a second that estimates the species composition of each waterfowl group. Point estimates for species-specific harvest can be computed by multiplying the estimated total harvest by the estimated proportion of the total harvest of each species. However, to date, no uncertainty estimates have been available. Here, we combine these two data sources to provide species-specific harvest estimates at the state and flyway level while characterizing the uncertainty via Bayesian estimation. We take a similar approach to Smith et al . (2022) , providing both estimates that treat yearly data as independent and estimates that share information across years via a random walk process. We then discuss the advantages and disadvantages of each approach.

BioRxiv↗

USGS2011

Migratory movements of waterfowl in Central Asia and avian influenza emergence: Sporadic transmission of H5N1 from east to west

Waterfowl in the genera Anas and Tadorna are suspected as vectors in the long‐distance transmission of highly pathogenic avian influenza H5N1. The former Soviet Republics of Central Asia are situated at an important migratory crossroads for these and other species of birds that bridges regions where the disease is prevalent. However, waterfowl movements through Central Asia are poorly quantified. In this study, historical data derived from over 80 years of bird ringing are combined with recent satellite tracking data to delineate migration routes, movement chronology and habitat use patterns of waterfowl in relation to H5N1 outbreak locations. Results confirm migratory linkage between breeding and moulting areas in northern Kazakhstan and southern Siberia, with non‐breeding areas in the Caspian, Black and eastern Mediterranean Sea basins, as well as with South Asia. However, unlike the situation in neighbouring regions, most notably western China, H5N1 outbreaks have not been recurrent in Central Asia after they were first reported during summer 2005 and spring 2006. These findings have implications in relation to potential sampling biases, species‐specific variation in migratory behaviour and continuing regional H5N1 transmission risks.

Siberia↗