Understanding Waterfowl: The Stiff-Tailed Ducks

These distinctive diving ducks are among the world's most interesting waterfowl

© Scott Fink

—By John M. Coluccy, PhD

I can clearly recall my first encounter with a ruddy duck. I was a young technician assisting with wetlands and waterfowl research on Manitoba's famed Delta Marsh during spring 1988. While in the marsh collecting plant data, I kept hearing a sputtering sound followed by a low belch. After hearing this sound repeatedly, I finally spotted the offender, a small chestnut brown duck with a long, cocked tail, black head with bright white cheeks, and a bill as blue as the sky. It was a drake that was busily going about the business of courtship, displaying his skills in an attempt to attract a mate.

The ruddy duck is a member of the stiff-tailed ducks, a fascinating group of eight closely related waterfowl species in the tribe Oxyurini. Their name is derived from the ancient Greek oxus ("sharp") and oura ("tail"). Most members of this tribe are easily distinguished from other waterfowl by their signature long, pointed tail feathers with stiff shafts that cock upward while at rest. They are compact birds with short, stubby necks, and their bills are stout and scoop-shaped. Stiff-tails range in weight from just under a pound for the smallest species, the masked duck, to more than five pounds for the largest species, the musk duck. Their wings are small for their body size, making takeoffs challenging and flight labored. Their legs are short and powerful, and their large webbed feet are set far back on the body, which is useful not only for diving but also for generating the necessary thrust to taxi across the water to gain flight. In fact, a ruddy duck's feet have two times more foot propulsion area per unit of body mass than a mallard's feet do.

Because of these adaptations, stiff-tails are quite at home on the water but extremely awkward on land. Not surprisingly, they are rarely observed out of the water and favor deep permanent wetlands. During the breeding season, ruddy ducks use large marshes, stock ponds, reservoirs, and deep-water wetlands with extensive stands of emergent vegetation and plenty of open water for takeoffs and landings. On migration and wintering areas, they can be found on brackish estuarine bays, large freshwater wetlands, lakes, rivers, reservoirs, and aquaculture ponds.

Because of their remarkable diving ability and other foraging adaptations, stiff-tails can dive to the silty bottoms of wetlands and exploit underwater foods that are largely inaccessible to other waterfowl. They are mainly tactile feeders, using their uniquely shaped, sensitive bills to probe the bottom for plant and animal foods. The ruddy duck's diet consists of roughly 70 percent plants and 30 percent animal foods. Favored plant foods include the seeds, tubers, and leafy parts of pondweeds, bulrush, widgeon grass, and muskgrass. Midge larvae are a primary source of animal matter in their diet.    

Many ruddy ducks depend on the shallow wetlands of the Prairie Pothole Region for breeding habitat.

Photo © Ken Archer

Stiff-tailed ducks are mainly found in warmer parts of the world. Thus, most species don't have to migrate long distances between breeding and wintering areas and instead make short seasonal migrations and nomadic movements in response to varying water conditions. A notable exception is the ruddy duck. Starting in mid-September, ruddy ducks typically depart their core breeding area in the Prairie Pothole Region and head to favored wintering areas along the Atlantic, Pacific, and Gulf Coasts. An especially long trip was documented for a ruddy duck banded in Saskatchewan; the bird subsequently was recovered in Chihuahua, Mexico, approximately 1,600 miles to the south.

The mating systems of stiff-tails vary considerably from one species to the next, ranging from seasonal monogamy (a single male and female form pair bonds each breeding season) to polygyny (a single male establishes pair bonds with multiple females) to promiscuity (males and females don't establish pair bonds and instead mate with multiple partners). Ruddy ducks establish pair bonds after arriving on breeding areas, which is unusual among North American waterfowl. Ruddies are often assumed to be seasonally monogamous, but observations suggest otherwise. Some males form no pair bonds at all, others attend mates for only a few days, and a few have two mates.

During courtship, male stiff-tails inflate specialized air sacs attached to their trachea. In the resulting "bubbling" display, the male ruddy duck beats its bill against the inflated air sac in its neck to create dull thudding sounds while generating a ring of air bubbles as air is forced from its feathers.

Females of most stiff-tail species lay relatively large eggs, often in the nests of other waterfowl. Their newly hatched young are among the largest and most independent among all waterfowl. Females who construct nests typically do so over water in patches of cattails or bulrush. Clutch sizes range from three to 10 eggs. The incubation period lasts from 22 to 26 days, which is surprisingly short given the size of the eggs. Among ruddy ducks, the weight of a full clutch of eggs often exceeds that of the hen that laid them.

Stiff-tails typically aren't considered important game species. In the United States, fewer than 30,000 ruddy ducks are harvested annually. Ruddies often get a bad rap when it comes to their suitability as table fare, but that may not have always been the case. A look at historical market lists from a century ago suggests a pair of ruddies fetched $0.25 to $0.90 compared to a brace of canvasbacks, which brought $1.00 to $2.75. When adjusted for weight, these prices were almost comparable. This isn't surprising when you consider that ruddy ducks often consume the same plant foods that canvasbacks do, such as sago pondweed. Ruddy ducks taste just fine, as I can personally attest.    

Like all waterfowl, stiff-tailed ducks are inextricably linked to the habitats on which they depend. Unfortunately, they are currently threatened by wetland drainage and degraded water quality on key breeding, migration, and wintering areas. In North America, ruddy ducks and other waterfowl benefit from Ducks Unlimited's efforts to conserve wetlands and associated upland habitats. This work also provides many broader ecological benefits, including clean water. Thus, conserving habitat for ruddy ducks and other waterfowl also makes the world a better place for people and a host of fish and other wildlife species. I believe we can all agree that is a wise investment. 


Dr. John Coluccy is director of conservation planning in DU's Great Lakes/Atlantic Region.