Credit: Chesapeake Bay Program
The ruddy duck, Oxyura jamaicensis, is a migratory diving duck that arrives in the Chesapeake Bay around mid-October. It often breeds in the lower Great Lakes region, central Canada and northern United States, and some groups winter along the East Coast as far north as Massachusetts. Populations of ruddy ducks also live year-round in central Mexico and the southwestern U.S. and some areas along the Pacific coast. Wintering populations in the Chesapeake Bay have declined in recent years.
These small (usually only 11 to 14 inches long), appealing diving ducks are excellent swimmers, and sometimes use their sharply angled, long tails as rudders when forced, for protection, to dive and swim. Like the canvasback (Aythya valisineria), a much larger diving duck common to the Bay, the ruddy duck feeds on aquatic vegetation, pondweed, the seeds of aquatic plants and insects, and mollusks.
In summer, in search of a mate, the male ruddy duck develops dramatic plumage that contrasts with its subdued winter browns and grays. The breeding male has a deep chestnut body, black head, rust-colored neck, white cheeks and brilliant blue bill. In winter the male's plumage resemble the year-round presentation of the female's, with its dusky brown body, pale cheeks and black bill. The white cheeks of the female are marked by a black or gray stripe. During the male's courtship display, which is called "bubbling," he often holds his fanlike tail erect and beats his breast with his brightly colored blue bill, which creates bubbles in the water. Breeding males behave aggressively toward one another.
The monogamous ruddy duck prefers nests surrounded by dense vegetation near freshwater marshes and ponds. It often acts as a "brood parasite," choosing the nests of other species in which to lay its surprisingly large eggs (this tiny species lays eggs that are larger than those laid by the much larger canvasback-more than two inches long). Sometimes the female will adopt the abandoned nests of other ducks such as the redhead (Aythya americana) or coot (Fulica americana). The male will usually leave the female while she incubates her clutch of between 5 and 15 eggs for a period of 23 to 26 days. Ruddy ducklings follow the mother during feeding until they fledge, which usually takes place between 42 and 48 days.
The ruddy duck is a shallow diver and feeds by straining bottom mud or surface water. It consumes aquatic plants and animals, including insect larvae, brine flies, water boatmen, dragonfly nymphs, clams, mollusks, shrimps and leeches. It usually sinks into the water slowly or dives to avoid danger but also can fly great distances during migration periods. It takes off somewhat awkwardly, using its legs and wings to 'run' across the water's surface before becoming airborne. Once in flight, the ruddy duck beats its wings so rapidly that some compare its flight to that of a large insect or hummingbird.
Posted: 12-4-2002
