Wood Duck
The wood duck is considered by many bird watchers to be North America's most colorful waterfowl species. Its scientific name, Aix sponsa, translates into "waterbird in bridal dress." Today the wood duck is one of the most common waterfowl species breeding in the United States. However, this was not always the case. Writings from the early 19th century indicate that wood ducks were in abundant supply and very popular for their tasty meat and bright decorative feathers. By the late 1880's, unregulated hunting and destruction of woodland and wetland habitat had caused the wood duck population to decline to alarmingly low levels. By the beginning of the 20th century, wood ducks had virtually disappeared from much of their former range.

In response to the Migratory Bird Treaty established in 1916 and enactment of the Federal Migratory Bird Treaty Act in 1918, wood duck populations began to slowly recover. By ending unregulated hunting and taking measures to protect remaining habitat, wood duck populations began to rebound in the 1920's. The development of the artificial nesting box in the 1930's gave an additional boost to wood duck production. Wood ducks eagerly accepted boxes as suitable nesting sites, and over the following fifty years, conservation groups and individuals helped increase numbers of wood ducks by preserving habitat and erecting nest boxes. The combination of hunting restrictions and habitat conservation and management measures enabled wood duck populations to rebound enough to support conservative hunting in the 1940's. The story of the wood duck is an example of how active wildlife management techniques can have a tremendous effect on the overall success of an individual species.

Range
The wood ducks' range extends on the east coast from Nova Scotia west to the north central U.S. and south to Florida and the Gulf of Mexico. Birds nesting in New England winter in the Atlantic states from the Carolinas southward. Midwestern wood ducks winter in the area extending from Georgia west to Texas. On the west coast, the wood ducks' range extends from British Columbia south to the Mexican border. Upper west coast wood ducks will winter in southern California and the Mexican Pacific coast. Southern breeding wood ducks are year-round residents. Fall migration generally begins in October and extends into November. Spring migration occurs during March and April. Wood ducks migrate either in pairs or in small flocks. Wood ducks respond well to habitat protection and restoration activities, and breeding pairs are increasing use of suitable habitat outside traditional breeding areas.

Habitat Requirements
General
Wood ducks nest in woodland areas along lakes, rivers, and vegetated wetland areas. During the winter months, wood ducks inhabit bottomland hardwood wetlands, beaver ponds and flowages, river oxbows, meanders and backwaters, and other inland freshwater forested wetland areas. Habitat areas chosen by wood ducks are commonly used by other waterfowl species such as black ducks, hooded mergansers, and ring-necked ducks. High-quality wood duck habitat is intricately linked to preservation and management of old growth timber along river corridors and availability of nesting sites. Although wood duck populations have recovered, the largest threat to their future is the continued loss of habitat. By protecting and restoring floodplain timber, river oxbows and meanders, and other freshwater wetland and riparian habitats, landowners can assist in the continued success of wood ducks and other migratory waterfowl species that rely on similar habitats.

Food
Food for young birds and adults differs dramatically. The early diet of ducklings consists largely of insects, aquatic invertebrates, small fish, and other high-protein animal material. After six weeks of age, the young switch to plant foods until their diet consists of approximately 90 percent vegetative material, primarily aquatic plants such as algae, watermeal, watershield, sago pondweed, and duckweed. Adult wood ducks feed on a variety of nuts and fruits, aquatic plants and seeds, and aquatic insects and other invertebrates. Insects and aquatic invertebrates are particularly important food items of adult hens during egg laying in spring. Acorns and other forest mast are important fall and winter foods. While acorns are the primary winter foods, the seeds of bald cypress, hickory, sweet gum, buttonbush, arrow-arum, bur-reed, and wild rice are also common winter foods. Wood ducks feed primarily in shallow water areas, but will also forage on the forest floor for seeds, acorns, and nuts.

The following species are known to be important food items in the diet of wood ducks.

oak (acorns), hickory (nuts), elm, bald cypress, beech (nuts), sweet gum,
ash, button bush, maple, blackgum, bur-reed, rice, cutgrass,
arrow-arum, wild rice, sedge, smartweeds, barnyard grass, nightshade,
cowlily, beggarticks, duckweed, grape, St. John's-wort, panic grasses,
bulrush, pondweed, watershield, waterlily

These species may be used to enhance vegetation which already exists in and around woodland areas and aquatic habitats. Adding these species to those currently existing will enhance food availability for wood ducks.

Cover - Nesting
Wood ducks nest in natural tree cavities and in some cases, those excavated and abandoned by woodpeckers. Nesting boxes are also readily accepted for nesting. Nesting pairs typically select cavities in deciduous woodland areas in close proximity to rivers, wetlands, and other suitable aquatic habitats used for brood rearing. Cavities located 30 feet or more above the ground are preferred, but the height can vary from near ground level to 65 feet. Suitable natural cavity dimensions typically have an entrance hole diameter of at least 4 inches, an inside diameter of approximately 6 to 8 inches, and a depth of at least 24 inches. Optimal nesting habitat contains up to five suitable cavities per acre in close proximity to brood-rearing habitat; however, since most natural cavities are not suitable for use by nesting wood ducks, these conditions frequently require that 50 or 60 natural cavities per acre exist. This illustrates the utility of providing suitable artificial nesting boxes to augment the availability of natural cavities.

Cover - Brood Rearing
Wood duck broods require shallow water for foraging on invertebrates and aquatic plants that contain some protective cover from predators. A ratio of 50 to 75 percent cover to 25 to 50 percent open water is preferred as brood-rearing (and breeding) habitat. Cover may be provided by trees or shrubs overhanging the water, flooded woody vegetation and debris, and herbaceous emergent vegetation. Ideal shrub cover is provided by mature shrubs that provide a dense canopy about two feet above the water surface. Button bush is an important shrub species in a large portion of the wood duck's range due to its brushy growth form, providing brood cover, and its prolific seed production, used heavily by foraging adults. Reliance on permanent, deeper water bodies for brood habitat should be avoided to minimize duckling mortality from aquatic predators such as snapping turtles and large fish.

Adult molting cover requirements are generally met by suitable brood-rearing habitat. Permanent water, cover, and food are the key elements of molting habitat.

Cover - Winter
In areas where wood ducks winter, areas similar to brood rearing habitat provide adequate winter cover. Bottomland hardwood wetlands and quiet river backwaters and streams with an abundance of partially submerged downed timber, shrubs, and woody debris are favored. Winter-persistent herbaceous emergent vegetation that has a shrubby-like life form (e.g., cattail, soft rush, bulrush, bur-reed, etc.) may also provide adequate winter cover. Security provided by overhead woody cover is the key element of good wood duck roosting habitat.

Nest Boxes
Nest Box Design
Nest boxes should be constructed of a weather-resistant wood; cedar or cypress is often recommended. The wood can be painted, stained, or treated, but only on the outside surface. The entrance hole should have a 4-inch diameter or be an oval that is 3 inches high and 4 inches wide. Numerous nest box designs have been used with success. A 3-inch wide strip of 1/4-inch mesh hardware cloth should be securely fastened to the inside of the box under the entrance to function as a ladder for the hen and newly hatched ducklings. The cut edges of this cloth should be folded back before insertion to avoid injury to the ducklings. Another method of assisting the ducklings in their climb from the nest to the entrance hole is to roughen up the wood surface under the hole with a chisel. A 3-inch layer of coarse sawdust should be placed at the bottom of the box to serve as nesting material and to help prevent the eggs from rolling around. The lid or one side of the box should be removable to facilitate monitoring and cleaning. All wood duck boxes should be fitted with a galvanized sheet metal predator guard. The predator guard should be placed 6 to 12 inches below the bottom of the box.

Nest Box Installation
Wood ducks are highly secretive in selecting nest sites to minimize impacts of nest predators and competition from other wood ducks. Therefore, it is important to locate individual nest boxes in relatively secluded areas within timber stands where natural cavities would occur naturally. Nest boxes can be placed either on land or over the water. If located over the water, they should be placed at least 4 feet above the high water level and the entrance hole should face the open water rather than the shoreline. Because of ease of access by predators, installation of nest boxes directly on trees should be avoided. Nest boxes placed on land should be located from 30 to 150 feet away from the shoreline. Boxes placed directly on the shoreline appear to be more likely frequented by nest predators. Since the hen must lead her ducklings to water soon after they hatch, the area between the nest box and the water's edge should be free of any major obstacles such as roads or fencing. Nest boxes placed on poles over water are generally more easy to monitor than those placed in trees. Regardless of whether the box is placed over the water or land, the entrance should be clear of obstructions to provide easy access for the ducks.

In order to maximize nest box use while minimizing nest dumping, it is generally recommended that nest boxes should be placed at least 600 feet apart and should not be visible to one another. When placing nest boxes in isolated locations, consider ease of access for monitoring purposes.

Nest Box Monitoring
Before nesting boxes are erected, a maintenance and monitoring plan to ensure the success of the program should be developed. Old nests and those of invasive species such as European starlings must be cleaned out regularly if the boxes are to be used more than once during a nesting season. The monitoring program should ensure that boxes are monitored at least once before the beginning of the nesting season, and should be checked at least once a month during the nesting season if multiple use of nest boxes per nesting season is desired. Boxes should remain out during the winter to provide winter cover sites for screech owls and other resident birds.

Water
Water requirements for wood ducks are assumed to be met where suitable brood-rearing and wintering habitat exist.

Interspersion of Habitat Components
In order for successful wood duck reproduction and survival to occur, all the habitat components must be available in relative proximity to one another. Since wood ducks are highly mobile during winter, the most critical aspect of habitat interspersion, or the mix of different habitat types, is the proximity of suitable brood-rearing habitat to nesting habitat in the spring. The highest-quality nesting habitat is of little use if the nearest brood-rearing habitat is more than a mile distant. Likewise, the best brood-rearing habitat will not support wood duck broods if there is no nesting habitat in the vicinity. In southern areas where wood ducks are year-round residents, the best habitats consist of a complex of forested wetland habitats that include live forest, green-tree reservoirs, rivers, oxbows, riparian corridors, beaver ponds, shrub-scrub and robust emergent herbaceous wetlands.

Minimum Habitat Area
Since wood ducks are able to nest at some distance from brood-rearing habitat, no reasonable estimate of minimum nesting habitat size exists. In addition, no good estimates for minimum wintering habitat area are available due to the high mobility of wintering birds. However, at least 10 acres of wetland or other aquatic habitat in a contiguous unit, or in isolated parcels separated by no more than 100 feet of upland, is needed in close proximity to nesting habitat to support brood rearing. Lands outside the immediate planning area should be considered when making the determination of minimum habitat area for wood duck reproduction.

Dump-Nests
While the normal brood size for wood ducks is 10 to 15, nests have been found to contain 30 eggs or more. These extra eggs are the result of "egg dumping" or intraspecific brood parasitism. Egg dumping occurs as a result of several factors, including nest predation and lack of available nest sites. Dumping occurs when a female wood duck, frequently a first-year breeder, follows another hen to hidden or scarce nest sites during the egg-laying period. The visiting bird is stimulated to lay eggs in the nest of the other hen. In the wild, this impulse is kept in check because wood ducks normally nest in isolated locations. Artificial nesting structures are often mistakenly erected close together and in highly visible locations, such as the center of a pond. This creates a situation where egg dumping is common, and overall reproductive success plummets. A hen whose nest is dumped with too many eggs may abandon it; the result is a huge amount of wasted reproductive effort. In a natural scenario, approximately 80 percent of eggs hatch. But where egg dumping is out of control, hatch rates may drop to as low as 10 percent. Because of this, it is critical to locate nest boxes in isolated locations as described above. If wood ducks are very rare in the area, it may be necessary to place boxes in open areas initially to encourage use, and then moving them to more secretive locations as the population increases.

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