Chesapeake Bay Waterfowl - Wood Ducks
Wood ducks add color to Bay's forested shorelines
Bay Naturalist / By Kathy Reshetiloff - Bay Journal
When it comes to Chesapeake Bay waterfowl, most people are familiar with commonly seen wintering birds like Canada geese. Those who frequent areas of open water and marshes of the Bay, might also see canvasbacks, buffleheads, black ducks and tundra swans. Explore the Bay's forested shorelines and its many tributaries during warmer months, though, and you might encounter one of the most beautiful ducks in North America, the wood duck.
The wood duck's beauty is even reflected in its scientific name, Aix sponsa. From the Greek word aiks for water bird and Latin word sponsa for betrothed, the name refers to plumage so striking that the wood duck looks like it is dressed for a wedding.
While wintering waterfowl are breeding on the tundra and prairies, wood ducks are breeding in the Chesapeake Bay watershed. Early colonists aptly called the woody the "summer duck." They have also been known as the Carolina duck, because of where it was first described, the swamp duck, because of its preferred habitat, and the acorn duck after one of its favorite foods.
Both drakes (males) and hens (females) have crested heads, ending in hood-shaped manes. The drake's head is iridescent green, blue, purple, black and white. Its eyes and eyelids are red, while the throat and breast are brown with lighter brown on sides and bellies. Hens, like most other female birds, are duller in plumage. Their heads and necks are gray and bodies are brown. Sporting a smaller mane, the female has a white teardrop patch around its eye. Wood ducks weigh between 1 and 2 pounds. Flight speed averages about 47 miles per hour. The call of the male wood duck is a delicate squeak, while the female has a much harsher call. The female's alarm call is a loud "weeek."
Wood ducks, so named because they nest in tree cavities, are found in wooded swamps and woodlands near ponds, streams and rivers. Preferred forest types include floodplain forests, red maple swamps, temporarily flooded oak forests and northern bottomland hardwoods with many perching sites. The wood duck's range nearly coincides with the U.S. borders and at one time it was considered as a possible national symbol.
Courtship takes place and pairs begin to form from autumn through spring. Wood ducks are monogamous, meaning one male breeds with one female. Nesting begins between mid-January, in the deep South, and early April in the northern part of its range.
The wood duck is associated with old growth timber, which provides a diversity of cavities high in the trees. The female builds her nest in a tree cavity that must be at least 8 inches in diameter, usually 30 feet or more above the ground or water. The nest cavity is lined with down and wood chips. Wood ducks often reuse the same nest year after year. The average clutch size is 12 eggs, which the female incubates for 28-37 days. Some wood ducks double brood, meaning they nest twice in a single year. They are the only North American waterfowl to do so.
Ducklings are born precocial, meaning they are mobile, downy and can find their own food. Young remain in the nest only 24 hours after hatching. The hen calls them out of the tree cavity from the water or ground below. Using their sharp clawed feet, the nestlings are able to climb out of the cavity and leap down, sometimes from as high as 60 feet, to land next to the mother hen waiting below. The young will never return to their nest again.The ducklings are able to fly 56-70 days after hatching.
Ninety percent of wood duck food is plant material including seeds, nuts, berries and grain. Wood ducks eats more nuts than any other North American duck. The rest of their diet is made up of land and aquatic insects. During breeding season, their diet consists mainly of aquatic invertebrates, including insects, crayfish, bivalves and snails.
Female wood ducks will also lay some of their eggs in other wood duck nests, leaving the raising of ducklings to other females. This is known as brood parasitism or dump nesting. Three causes are noteworthy. Females nesting for the first time may follow older females to hard-to-find nest sites and then dump their eggs in the older hen's nest. A female that loses its nest will not deposit its eggs on the ground or in empty nests, but will seek out active nests in which to lay the remainder of her eggs before renesting. The third cause is competition for suitable nest sites when wood ducks are unusually productive and populations are high.
Dump nesting is a productive trait. After a parasitic female has dumped her eggs, the resident female begins incubation. Her presence on the nest will deter entry by other parasitic females. The eggs are synchronized to the laying period and hatching success is high.
Eggs are preyed upon by raccoons, opossums, some snakes and birds. Flightless ducklings are also preyed upon by snapping turtles, mink, large fish and additional species of snakes. But humans impact wood ducks the most.
Unregulated hunting took its toll on the wood duck. Large roosts of migrating wood ducks made them an easy target for market hunters who decimated wood ducks and other waterfowl to satisfy the demand for game meat by grocers, restaurants and hotels. This, combined with the loss of habitat of both wintering and nestings grounds from poor forestry practices and clearing for agricultural, residential and industrial development, almost caused the wood duck's extinction around turn of century.
In 1918, the Migratory Bird Treaty Act outlawed market hunting of migratory waterfowl. Soon after, both the United States and Canada banned the taking of wood ducks. To address the loss of natural tree cavities for nesting, state game departments, sportsmen's organizations and the federal agencies began installing nesting boxes that wood ducks would readily use.
In 1942, hunters in the Atlantic and Mississippi Flyways were allowed take one wood duck per day.
Conservative bag limits and improved nesting habitat along riparian corridors have greatly aided the comeback of the wood duck. Today, more than 1 million wood ducks are harvested every year. The wood duck also exceeds both the mallard and black duck in harvest in many states in the East. With continued efforts to provide artificial nesting boxes and protect natural nesting habitat, wood ducks have again become one of the most bountiful duck species!
Kathryn Reshetiloff is with the U.S. Fish and Wildlife Service’s Chesapeake Bay Field Office in Annapolis.
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