State of the Ducks

A closer look at the remarkable diversity of North America's ducks and the status of their populations

Edited by Dale Humburg

Generally speaking, we live in an era of abundant waterfowl populations. Most goose populations are currently healthy, and duck populations have reached the highest levels recorded since breeding ground surveys were standardized in 1955. In the traditional survey area, which encompasses the prairies, parklands, and much of the Western Boreal Forest and Alaska, total breeding duck numbers have averaged 41.8 million birds during the past decade, peaking at 49.2 million in 2014. In the eastern survey area, encompassing much of eastern Canada and parts of the northeastern United States, surveys indicate that breeding ducks have been relatively stable, averaging 2.65 million birds over the past 25 years. When other surveys are included from states in the West, the Great Lakes region, and the Northeast, the continent's total annual population of breeding ducks is upwards of 60 million birds.

North America is blessed with a remarkable variety of ducks comprising some 35 species. These birds have filled diverse ecological niches across this continent, resulting in great variation among species in physical appearance, distribution, breeding habits, food preferences, and a number of other characteristics. While most ducks are commonly classified as either dabblers or divers, taxonomists have grouped the birds into more specific assemblages of six "tribes." Within these tribes, some duck populations are increasing, others are generally stable, and still others have recently suffered declines. The following review of each tribe provides a general summary of the state of North America's ducks as well as the challenges currently facing their conservation.

DABBLING DUCKS

North America's dabbling duck tribe includes mallards, northern pintails, gadwalls, American wigeon, blue-winged teal, green-winged teal, cinnamon teal, northern shovelers, American black ducks, and mottled ducks. More than two decades of exceptionally wet conditions across the Prairie Pothole Region have resulted in abundant breeding populations of most prairie-nesting dabblers. During this period, mallard, blue-winged teal, gadwall, and northern shoveler populations have consistently exceeded their long-term (1955–2014) averages. Gadwall and northern shoveler populations have steadily and rapidly increased, currently exceeding their long-term averages by more than 100 percent. After declining from abundant levels in the 1970s, northern pintails did not respond as positively as other duck species following the prairie drought of the 1980s and early 1990s. Over the past two decades, the northern pintail population has averaged about 3 million birds, which is roughly 25 percent below the long-term average.

American wigeon and green-winged teal primarily breed in the Western Boreal Forest of Canada and Alaska. During the past 20 years, green-winged teal populations have steadily increased to a level more than 50 percent above the long-term average. American wigeon declined from highs in the 1970s and remained below the long-term average during most of the past two decades. In 2014, however, American wigeon numbers in the traditional survey area were up 18 percent from the previous year's estimate and 20 percent above the long-term average.

Outside the prairies, populations of American black ducks in the East, mottled ducks along the Gulf Coast, and cinnamon teal in the West are less abundant than other dabbling ducks and present unique conservation challenges for waterfowl managers. In the eastern survey area, black duck breeding populations have been relatively stable since 1990, and the 2014 estimate of 619,000 birds was similar to the long-term average. Continued loss and degradation of habitat in core breeding, staging, and wintering areas and uncertainty about future climate impacts are the primary threats facing this species. Mottled ducks, a nonmigratory relative of the mallard and black duck, live along the Gulf Coast, primarily in Louisiana and Texas. Smaller populations of mottled ducks are found in peninsular Florida and South Carolina. Coastal marsh loss and declining rice agriculture along the Gulf Coast are the biggest concerns for this species. The cinnamon teal is another dabbler with a relatively restricted range. Numbering only a few hundred thousand birds, cinnamon teal are somewhat common in the Pacific and western Central Flyways, but relatively uncommon elsewhere.

While most dabbling duck populations are currently in good shape, waterfowl managers remain concerned about northern pintails and American wigeon, and substantial challenges lie ahead for the conservation of all dabbling ducks. On the prairies, the greatest threat facing duck populations is conversion of wetland habitat and nesting cover to annually cultivated cropland. Most of the breeding habitat used by waterfowl on the prairies is privately owned and largely unprotected from conversion. Moreover, increased demand for commodity crops is creating pressure to drain wetlands and convert grassland and other nesting cover to cropland at rates not seen since the 1930s. As a result, the future of prairie duck populations rests with effective policies and programs that provide incentives to conserve wetlands and nesting cover on working agricultural lands. Because precipitation and wetland conditions can vary widely from year to year on the prairies, these conservation efforts must be implemented across the entire region to ensure that ducks will find adequate habitat to support healthy breeding populations.

In the Western Boreal Forest, dabbling duck populations are faced with expanding and intensifying natural resource development. The frequency and intensity of forest fires and wetland losses are also increasing. More scientific research on the impacts of landscape change and continued implementation of public policies that conserve wetlands and other key habitats are needed to ensure a bright future for breeding dabbling ducks in this vast region. —Johann Walker, Ph.D.

DIVING DUCKS

North America's diving duck tribe consists of five species: the canvasback, redhead, ring-necked duck, and greater and lesser scaup. Among these species, only scaup are considered abundant. Because it's difficult to distinguish between greater and lesser scaup from the air, the two species are counted together during annual waterfowl population surveys. Scaup have an expansive breeding range that extends from the northern United States through the Prairie Pothole Region to the Bering Sea, with the largest numbers of these birds breeding in the Western Boreal Forest of Canada. In 2014, scaup had an estimated breeding population of 4.6 million birds in the traditional survey area. Scaup have suffered a long-term decline since the 1970s and have only recently approached their long-term average. Ring-necked ducks also breed predominantly across the Boreal Forest. In contrast to scaup, however, the ring-necked duck population has been relatively stable, with an annual average of about 500,000 birds in the eastern survey area.

The majority of canvasbacks and redheads breed on the prairies. In addition, significant numbers of canvasbacks nest in the Western Boreal Forest as far north as Alaska, and impressive concentrations of nesting redheads occur in the marshes of the Great Basin. Although populations of canvasbacks and redheads have been highly variable since surveys were initiated, the long-term trend for both species has been relatively stable. Breeding populations of canvasbacks and redheads in 2014 were estimated to be 685,000 and 1.3 million birds, respectively, with both species above their long-term averages.

The greatest threat currently facing canvasback and redhead populations is wetland drainage and degradation on the prairies. Farther north, in the Boreal Forest, natural resource development and climate impacts are the primary concerns for breeding scaup and ring-necked ducks. In addition, diving ducks have suffered more than other waterfowl from deteriorating water quality on migration and wintering areas. Historically important diving duck habitats such as Chesapeake Bay, North Carolina's coastal estuaries, the Illinois River, and shallow lakes in Wisconsin and Minnesota have been severely degraded by increased turbidity, excessive nutrient loading, and coastal erosion. On other important diving duck staging and wintering areas, including the Great Lakes and San Francisco Bay, accumulation of chemical contaminants in filter-feeding mussels could adversely affect scaup and other diving ducks that forage on these mollusks. —John Coluccy, Ph.D.

SEA DUCKS AND MERGANSERS

North America is home to 15 species of sea ducks and mergansers, which are combined as a single tribe. The Boreal Forest is the primary breeding area for several of these species, including scoters, mergansers, buffleheads, harlequin ducks, and Barrow's and common goldeneyes. Other species, such as eiders and long-tailed ducks, breed in remote Arctic or marine regions outside traditional waterfowl survey areas. Like scaup, four groups of sea ducks (scoters, eiders, goldeneyes, and common and red-breasted mergansers) are primarily counted together in surveyed areas, and other species are not surveyed at all on an annual basis. Thus population trends are unavailable for many individual sea duck species. However, some sea ducks have clearly suffered significant population declines in recent decades. Barrow's goldeneyes and the eastern population of harlequin ducks are listed as species of special concern in Canada and as threatened in Maine, and spectacled eiders and Alaskan-breeding Steller's eiders are listed as threatened in the United States.

During the breeding season, nesting sea ducks disperse across large areas of remote tundra and forests or gather in colonies, typically on islands associated with freshwater or marine systems. While staging and wintering, sea ducks spend most of their time on the ocean, where they sometimes gather in huge concentrations. Until recently, biologists didn't know the locations of key breeding, migration, and wintering areas for several sea duck species. Fortunately, satellite telemetry has helped biologists identify many key sea duck habitats. Additional research will be needed to gain a more comprehensive understanding of sea duck habitat requirements and to develop conservation strategies to sustain healthy populations of these birds. —Stuart Slattery, Ph.D.

PERCHING, STIFF-TAILED, AND WHISTLING DUCKS

The wood duck is the only native member of the perching duck tribe in North America, although some authorities now include them with the dabbling ducks. Wood duck populations were once in serious decline as a result of market hunting and deforestation. Fortunately, responsible harvest management and conservation efforts, such as the reforestation of bottomland hardwood habitats and the provision of nest boxes to compensate for a lack of natural nesting cavities, helped wood duck numbers rebound during the latter half of the 20th century. Although wood duck populations are currently believed to be either stable or increasing across their range, comprehensive estimates of wood duck breeding populations and annual production are currently unavailable due to the difficulty of surveying birds in forested habitats. New survey methods to help fill these knowledge gaps as well as the conservation of forested wetlands will be essential to the continued health of this species.

There are two species of stiff-tailed ducks in North America: the ruddy duck and masked duck. Populations of ruddy ducks appear to be either stable or increasing across their primary breeding area—the Prairie Pothole Region. An analysis of May waterfowl survey data suggests that ruddy ducks have an average breeding population of just over 400,000 birds. As is the case for other prairie-breeding waterfowl, wetland drainage is the greatest threat currently facing this species. Likewise, introduction of exotic aquatic species, pollution, and sedimentation have altered important nonbreeding habitats and possibly resulted in declining numbers of ruddy ducks on traditional migration and wintering areas such as Chesapeake Bay.

While the masked duck is only an occasional visitor to Louisiana and Florida, South Texas has the highest density and the only known breeding population of these birds. A comprehensive survey along the Texas Gulf Coast during the early 1990s tallied approximately 3,800 breeding masked ducks. Currently, very little is known about the life history of the masked duck in North America. More information, especially regarding habitat use by this species, would help biologists develop management recommendations for these birds.

The whistling duck tribe is composed of nine species worldwide; however, only fulvous and black-bellied whistling ducks occur in North America. In the United States, these birds breed primarily in Florida, Louisiana, and Texas. While comprehensive population data is limited, both species appear to be stable or increasing throughout most of their range, and band recoveries and field observations indicate that black-bellied whistling ducks are expanding their range into several other southeastern states. More reliable population estimates as well as a better understanding of these species' habitat requirements are needed to develop specific conservation strategies for these interesting birds. —J. Dale James, Ph.D.

SIX TRIBES, MANY CONSERVATION CHALLENGES

Clearly, the status of North America's duck populations varies considerably among regions and species. Blue-winged teal, northern shovelers, and gadwalls have apparently adapted well to landscape changes on the prairies and benefited most from recent wet weather and habitat conditions in the Prairie Pothole Region. Other species, such as mallards, canvasbacks, redheads, and green-winged teal, seem to be holding their own. Long-term declines in scaup and northern pintail populations are troubling and present particular challenges for waterfowl conservationists. And as a group, sea ducks are notable because of the uncertainty about the population status of several species and the potential impacts of emerging ecological threats.

Each species is a unique and precious natural resource, and we have a responsibility to ensure that all of this continent's ducks continue to grace our skies in healthy numbers. For well-studied species, we must continue to monitor their numbers and keep working to conserve the habitats these birds need to thrive. For less-studied species, such as the sea ducks, additional research will be required to learn more about their population status and habitat requirements, so we can develop effective strategies for their conservation. Generations of waterfowl managers and conservationists have worked together to ensure that we have abundant and diverse duck populations. As we celebrate this year's impressive duck populations, let us rededicate ourselves to conserving the habitats that will be required to sustain these remarkable birds for future generations to enjoy.