Wintering Waterfowl on the Potomac

By Glenda C. Booth

Alexandria, VA – Motorboats, sailboats, and jet skis may be stored for the winter, but the Potomac and area waterways are far from quiet. Come winter, come waterfowl.

“I used to think winter was something to get through,” says Alexandrian Paula Sullivan. “Now I look forward to it because I get to see the birds that arrive from the North.”

The Potomac River and other area waters attract thousands of waterfowl every winter, birds that fly south from their breeding grounds in northern Canada and Alaska. Birds migrate to use resources, especially food, that are seasonally abundant and to avoid places where resources are scarce or weather is very harsh.

Waterfowl are ducks, geese, and swans. These birds generally have webbed feet and flat bills and must have aquatic habitats like rivers, lakes, streams, wetlands, or the ocean.

In winter, many species gather in groups, sometimes called “rafts.” Many have subdued plumage which, by winter’s end, brightens up for spring mating. Many waterfowl species are dimorphic, meaning males have bolder colors and markings than the more mottled females.

An October National Audubon Society study reported that North America’s bird populations have plummeted 29 percent since 1970, but the study has some good news for waterfowl. Duck and geese numbers have risen by around 50 percent.

Ducks

Generally, there are two types of ducks – dabblers and divers. Dabbling ducks, sometimes called “puddle ducks,” feed in shallow water by tipping forward, dabbling or putting their head in the water to feed on vegetation, larvae, and insects while poking their butts straight up. Or they may skim the surface of the water for food. Diving ducks dive underwater, feed on clams and fish, and propel themselves underwater.

Dabblers on the Potomac in winter include wood ducks, mallards, northern shovelers, gadwalls, northern pintails, and American black ducks. Diving ducks include lesser scaups, buffleheads, ruddy ducks, mergansers, and canvasbacks.

Dixie Sommers, an avid, long-time birder, likes to watch hooded mergansers on the river in winter. The male has a striking white “hammerhead” crest or hood bordered with black, a black face, neck and back, a white breast, and chestnut-colored sides with accents of white stripes. The female has a cinnamon-colored crest. These birds have an extra eyelid, called a nictitating membrane, which is transparent and protects their eyes like goggles while they are underwater. In late winter and early spring, when hormones begin to stir, males raise their crest and throw their heads abruptly backward, almost touching their back. As they return their heads to the upright position, they make a frog-like, croaking call to attract females.

Geese

Geese are long-necked birds, larger than ducks, that feed by tipping up or grazing. They usually gather in flocks. The most common geese in the Washington area, present year round, are Canada geese, birds with black necks and beaks, brown breasts, and white cheeks.

Former President Jimmy Carter wrote a poem about Canada geese flying over Washington, in which he related going to the White House roof where he “heard a sound primeval in its tone and rhythm.” He watched “in silence long wavering V’s, breasts transformed to brilliance by the lights we would have dimmed.”

Golfers are unlikely to feel as warmly as Carter toward these feathered fauna. Canada geese love to graze on golf course turf grass, and they leave behind significant deposits.

Swans

Swans are the largest of all waterfowl, with long necks, heavy bodies, and big feet. Swans fly with slow wingbeats and necks outstretched. Their all-white plumage, beauty, and graceful motion have inspired musicians from Sibelius to Tchaikovsky. Think of ballerinas dancing to Swan Lake.

Tundra swans are especially striking with their black bills, black legs, straight necks, and high-pitched, bugling calls. Because their wings “whistle” when flying, American explorer Meriwether Lewis called them whistling swans. They fly with outstretched necks and have a six- to seven-foot wingspan. Tundra swans eat aquatic plants, tubers, invertebrates, mollusks, snails, mussels, and shellfish.

From October to March, sometimes hundreds of tundra swans mass off Mason Neck on the Potomac, in southern Fairfax County. In February, they head to their breeding grounds on the northern slopes of Alaska and on Canada’s Hudson Bay.

There are other duck-like, swimming birds in our area’s waters, in both winter and year-round, that technically, are not called waterfowl. These include grebes, cormorants, and American coots. Keen observers like Mount Vernon resident Ed Eder have spotted loons and shorebirds during the spring and fall migrations.

Are Numbers Declining?

Winter waterfowl numbers vary for several reasons, but problems on breeding grounds often result in lower winter populations in the mid-Atlantic region. “If the numbers go way down, it means that conditions for breeding went wrong,” explains Mike Bowen, an Audubon Naturalist Society volunteer.

Surveyors in the February 2019 Potomac River waterfowl count observed 28 waterfowl species. The count area stretched from Loudoun County to the river’s mouth. “Waterfowl populations on the Potomac have been low the last couple of years,” says Greg Butcher, vice president of the Audubon Society of Northern Virginia. “People think that’s because of heavy spring rains depressing the amount of submerged aquatic vegetation (SAV).”

SAV, also called underwater grasses, are plants that grow in the water up to the surface. These aquatic plants provide refuge for small fish and shellfish. The roots, shoots, and seeds provide high carbohydrate food to many waterfowl species. Events like heavy rains, sedimentation, and algal blooms that block light and reduce water clarity depress SAV growth.

Conditions were poor in 2018, reports Nancy Rybicki, a U.S. Geological Survey Aquatic Plant Ecologist Emerita. “The SAV never recovered in 2019, but could by 2020, if the past is any indication of the future. Healthy patches could spread back into the tidal Potomac,” she says. Veteran birdwatcher Larry Cartwright adds, “SAV is essential to waterfowl’s winter survival. If they can’t find it, they move on.”

Why watch waterfowl? “They are beautiful and they are interesting,” says Bowen. Butcher agrees. “People love waterfowl because of their inherent interest. They have large flocks and in spring, we can watch their courtship displays. They are also excellent indicators of the health of the aquatic environment. The different species have different requirements, so we can learn something different from each species.”

How and Where to See Waterfowl

Viewing waterfowl can be challenging for novices. It typically means standing on the shoreline in winter’s chill, staring at black humps or upended duck butts out in the river. “Notice the silhouettes,” says Casey Early, “they look like ants.” Early, a Mason Neck State Park ranger out on a cold November day under a steel gray sky, notes that, for diving ducks, it’s a now-you-see-them-now-you-don’t experience, as the birds disappear underwater and then suddenly pop up elsewhere.

Viewing with a spotting scope enhances the experience for most newbies, because it enables them to see the birds’ gleaming colors and vivid wing patterns, different body sizes, heads, and varied beak shapes. Behaviors like sleeping, head bobbing, preening, stealing food, and driving off competitors can be intriguing, and courtship displays are elaborate and captivating.

People new to waterfowl watching may benefit from accompanying experienced bird watchers who have spotting scopes. The more people see and study waterfowl, the more intrigued most become.

Popular watching sites along the Potomac River include Gravelly Point, the Washington Sailing Marina, Jones Point Park, Belle Haven Park, the Dyke Marsh Wildlife Preserve, Riverside Park, and Mason Neck State Park and Wildlife Refuge. Area wetlands, ponds, and lakes attract waterfowl as well.

Please note: One should never disturb or feed waterfowl. Human foods, like crackers and bread, are for humans; they are not suitable bird food.

Waterfowl Walks

Several groups lead waterfowl walks: Audubon Society of Northern Virginia, Audubon Naturalist Society, Friends of Dyke Marsh, Friends of Mason Neck State Park, Friends of Huntley Meadows Park, Northern Virginia Bird Club

Waterfowl Events

· “Winter Waterfowl of the Potomac River,” a talk by Greg Butcher, Vice-President, Audubon Society of Northern Virginia and Migratory Species Coordinator for the U.S. Forest Service, January 12, 2020, 2:30 to 5 p.m., National Wildlife Federation, 11100 Wildlife Center Drive, Reston, VA. Visit www.audubonva.org.

· Annual waterfowl survey of Fairfax, Arlington, and Prince William Counties, February 8 and 9, 2020, www.audubonva.org. Email [email protected] or call 703-438-6008.