Of the many wildlife management practices the private landowner can do, few are as rewarding as those which favor wood ducks. Wood ducks and a multitude of other wildlife species respond readily to managed wetlands. If new wetlands are constructed with duck production in mind, wood ducks will use them for nesting, brood rearing, and roosting. Even where wood ducks already live, their numbers can be increased through management. Nationally, as more and more natural wetlands are drained and converted to agricultural, industrial, and residential uses, the remaining waterfowl production areas will be increasingly important. Conservation practices on existing wetlands and creation of new wetlands on private lands are keys to sustaining valuable wildlife resources.
Wetlands and other water bodies managed for wood ducks and other wildlife are important parts of a larger picture. Historically, wood ducks prospered along waterways because surrounding forests provided food and nest sites. Cutting timber along streams and rivers devastated habitat for ducks, raccoons, songbirds, and many other kinds of wildlife. Beaver became rare, further reducing wood duck breeding areas. Meanwhile, hunting bag limits and seasons were liberal, resulting in over harvests and consequential declines in wood duck populations.
In the 1930s, wildlife conservationists and sportsmen strongly supported limitations on hunting. Wildlife biologists determined that wood ducks would use manmade nesting boxes. Thousands were put up across the range of the wood duck. At about the same time, farmlands abandoned in the early decades of this century became forest land. Also, beaver populations expanded, creating ideal habitat for wood ducks. This combination of responsible actions by man and the increase in suitable habitat has resulted in the current healthy population of several million wood ducks.
However, new problems for the wood duck are becoming evident. Bottomlands are being logged off, drained, and converted to farmlands. Other forests are maturing, inviting timber harvesting. Regrettably, some logging operations are done without regard for streambank protection, water quality, wood ducks, and other wildlife. Progressive foresters encourage landowners to leave bands of hardwoods at least 55 yards wide on each bank along all streams and rivers. Maintaining streamside stands of hardwoods secures habitat for wood ducks, other forest wildlife, plants, and aquatic life.
New ponds or wetlands developed in wooded drainages will attract and hold waterfowl. Wood duck habitat can be created by diverting water from streams into impoundments or by catching runoff and spring water behind earthen dams. Owners or managers should not use standard farm or fish pond construction guidelines, which call for average depths in excess of three feet, steeply sloping sides, brush-free banks, and bulldozed, uniform bottoms (figure 1). Ponds built for ducks should be shallow (not more than 2.5 feet deep) and contain one or more small islands. Although woodies do not use islands for nesting, other desirable waterfowl such as mallards and black ducks do use islands. Where feasible, the banks of the pond and the islands should be sloped gently (not more than 20 percent or a 1 to 5 slope) to permit ducks to walk up on shore. A convenient drainage system is needed to lower water levels and expose the bottom of the pond (figure 2).
Gently sloping banks encourage emergent aquatic plants to grow. Trees and shrubs at the upper end and sides of the pond and emergent, marshy vegetation should be allowed to grow. Besides providing food, aquatic vegetation supplies cover and protection for ducklings.
The USDA Soil Conservation Service provides landowners with free engineering advice on pond construction through its local offices. The landowner must specify the objective is duck production and not fish. And the owner should emphasize the need for shallow areas and a water-level regulation system, otherwise a conventional pond will be designed. Ponds of several acres or more can be constructed to support waterfowl and fish by creating a deep area near the dam and making the upper reaches shallow (figure 3).
Many people interested in enhancing their ponds for waterfowl are unaware of the attractiveness, availability, and importance of naturally occurring plants. Draining the pond in the summer to expose its mudflats encourages smartweeds and other favorite duck foods to grow. The pond should be drained in mid-June in mid-Atlantic and southeastern states. In more northern areas drainage should wait a few weeks longer, until the young ducks can fly. Seeds from annual plants that live in wet areas remain viable in the soil for years. These seeds will germinate in moist, exposed soil free of dense vegetation. If vegetation in the shallows is too thick, space available for new growth can be exposed by cutting, mowing, burning, or disking. When flooded in the fall, these shallow areas may support food in greater variety and amount than if they were planted with millets and other cereal grains. This practice, called moist-soil management, saves the owner money and time.
Moist-soil management of waterfowl impoundments is not recommended for the Northeast and other areas where purple loosestrife grows. This exotic plant develops dense stands in shallow wetlands, choking out habitat for waterfowl and other wildlife. Landowners concerned with purple loosestrife control should contact state or federal wildlife agencies for advice.
Newly flooded ponds are free of aquatic vegetation and therefore may not attract and hold ducks, even if the ponds have been designed for waterfowl. It usually takes several years for this vegetation to develop naturally. Anticipating a need to quickly establish water plants for food and cover, the landowner should have the soils in the shallow reaches of the pond analyzed. Wet or dry soil samples can be used. The local Cooperative Extension Service Agent can help the landowner get the soil samples analyzed and interpret the laboratory report. Japanese millet is a good choice for planting. Some managers wait for the mudflats to dry out enough to permit disking, liming, fertilization, and seeding (figure 4). Managers who are certain that the mudflats are sufficiently fertile walk through the damp flats and seed the millet with a cyclone seeder. Ponds are reflooded in the fall, after the millet develops seed heads (figure 5).
Wood ducks nest in cavities in trees unlike mallards, black ducks, and most other ducks. The cavities that wood ducks choose for nesting occur naturally in trees over 11 inches in diameter; they are typically 5x5 inches in cross-section, 22 inches deep, have entrance holes that are 4 inches in diameter, and are located 25 feet above ground. However, cavities suitable as wood duck nests take a long time to develop in nature. In young forests, such cavities are often in short supply, limiting not only the numbers of wood ducks, but also the abundance of squirrels, raccoons, owls, and other forest wildlife. Fortunately, landowners do not have to wait decades for natural cavities to form, because wood ducks will use artificial nest boxes.
Placement of wood duck nesting boxes over or near water that has abundant brood habitat can produce dramatic results. At first, wood ducks may not occupy many houses, but after a few years half or more of the nest boxes may be occupied. One reason for slow acceptance is that ducks reared in natural cavities search first for similar natural structures for nesting. However, birds hatched in nest boxes tend to choose nest boxes rather than cavities in trees for nesting. A beneficial consequence of this imprinting behavior is that the landowner with a successful nest box program will develop a breeding flock of ducks that return along with their young each year. Once the pattern is established, more nest boxes can be erected.
It is possible to place two or more nest boxes on the same structure (figure 6). Although multiple nest boxes have been successful, researchers have observed that fighting among nesting birds can lead to desertion. Dump nesting, the placement of eggs in the nest of other hens by hens that do not incubate their own eggs, has been observed in multiple nests. For these reasons, it is probably best to start out with single nest boxes. Once a flock is established, the number of nest boxes can be increased about 10 percent each year. One man in the northern piedmont of Virginia started with a few wood duck nest boxes 25 years ago and one pond. Now he has developed five additional ponds and has set out 30 nest boxes. Each year about half of the nest boxes prove successful, and over 125 wood ducks are produced on not more than 20 acres of managed wetland. An additional benefit is that he sees flocks of hundreds of migrating wood ducks on his ponds, which are managed for Japanese millet production.
Plumage: The wood duck is regarded as the most beautiful North American duck. The male's breeding plumage of maroon, white, blue, green, red, brown and black is truly captivating. The hen has grayish-brown feathers, a white chin and throat, and white eye rings. The wood duck is the only native duck with a smoothed down crest.
Classification: The wood duck is a member of the duck and goose family, Anatidae. Its scientific name is Aix sponsa.
Body Characteristics: Wood ducks are medium-sized ducks, usually weighing about 1.5 pounds. Body length is 17-20 inches. Wings are broad and short, with a span of 30 inches; such wings aid flight through woods and other tight cover. The flight speed of wood ducks is 39-55 miles per hour.
Range and Habitat: Wood ducks live in hardwood swamps, beaver ponds, meandering streams, and rivers and artificial ponds surrounded by mature timber. During the breeding season, they are distributed across the eastern United States and southern Ontario to Florida and west to Minnesota and Texas. Breeding populations are found on the west coast in California, Oregon, and Washington. Eastern wood ducks winter in the southeast, and western ducks winter in California.
Reproduction: The drakes and hens form pairbonds by late winter. The hen nests in a cavity in a tree or nesting box. The average clutch size is 9-12 dull white eggs. Eggs are laid one per day until clutch is completed. The incubation period is 28-37 days. Pairbonds last until just before the eggs hatch. Ducklings remain in the nest for 24 hours before their mother calls them out, whereupon they jump to the ground or water surface. The hen stays with her brood until the young can fly at 8-10 weeks of age. Some first-year nesting females will lay their eggs in the nests of other females. Called 'dump resting,' this behavior is more common when suitable nesting sites are in short supply.
Preferred Foods: Adults favor acorns, beech nuts, berries, bald cypress cones, duckweed, sedges, wild grapes, and wild rice. Ducklings depend upon small invertebrates for the first 2 weeks. These invertebrates, including mayfly and dragon fly nymphs, are abundant in masses of aquatic plants.
Survival: Up to 90% of the ducklings will die in the first 2 weeks. For ducklings from 2 to 6 weeks old, the mortality rate is about 50%. After gaining flight and up to 1 year, the mortality rate is about 75%.
Predators and Competitors: Starlings, common goldeneyes, hooded mergansers, American kestrels, squirrels, screech owls, and wasps will compete for the nest cavities and boxes. Nesting hens, eggs, and ducklings are preyed upon by raccoons, fox squirrels, gray squirrels, mink, opossums, rat snakes, snapping turtles, fish, and predatory birds.
Richen Brame, Robert H. Giles, Jr., W. Carter Johnson, Fant Martin, Frank McGilivery, LeRoy Sowl, and Dick Winter for comments on the manuscript. Appreciation is due to V. Daniel Stiles for his support.
Reviewed by James Parkhurst, Extension Specialist, Fisheries and Wildlife Science
Virginia Cooperative Extension materials are available for public use, re-print, or citation without further permission, provided the use includes credit to the author and to Virginia Cooperative Extension, Virginia Tech, and Virginia State University.
Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department of Agriculture cooperating. Alan L. Grant, Dean, College of Agriculture and Life Sciences; Edwin J. Jones, Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; Jewel E. Hairston, Administrator, 1890 Extension Program, Virginia State, Petersburg.
May 1, 2009