The wood duck (Aix sponsa) is one of the few North American waterfowl species that nests in tree cavities, relying on natural hollows in mature bottomland forests. Due to the decline of these natural nesting sites, artificial nesting boxes have become a widely adopted conservation tool to support the species’ reproductive success. Proper placement of these boxes is paramount, as a poorly situated box can expose nesting hens and eggs to high rates of predation or abandonment. Understanding the wood duck’s habitat needs and following specific mounting guidelines translates into higher occupancy rates and successful broods.
Selecting the Ideal Water Habitat
Wood ducks prefer secluded wetlands with permanent or semi-permanent water that persists through the nesting and brood-rearing season. Ideal locations include shallow marshes, quiet sloughs, slow-moving creeks, flooded timber, and the swampy margins of larger ponds and lakes. The water should generally be less than three feet deep over at least 75% of the area, providing accessible foraging grounds for ducklings.
Dense, emergent vegetation (such as cattails, sedges, and buttonbush) is important for brood survival. This cover provides overhead protection from avian predators and allows newly hatched ducklings to forage safely. Boxes should be placed in the immediate vicinity of this habitat, as the hen must lead her flightless young to water within 24 hours of hatching.
Choosing a site that is visually isolated from other nest boxes helps prevent “dump nesting,” where multiple hens lay eggs in the same box, often leading to nest abandonment. Separating boxes by at least 100 yards, or positioning them so they cannot be seen from one another, reduces this intraspecific competition. While wood ducks may nest up to a half-mile from water, closer placement minimizes the dangerous overland journey for the young ducklings.
Specific Mounting Dimensions
The mounting setup differs significantly depending on whether the box is placed over water or on land. Placing the box over water is preferred because it offers a natural barrier against climbing predators. When mounted over water on a pole or post, the bottom of the box should be at least four feet above the highest anticipated seasonal water level. The entrance hole is often mounted between 52 and 60 inches above the high-water mark.
If the box is placed on land, it should be situated within 30 to 100 feet of the shoreline, with an unobstructed path to the water. Land-mounted boxes require greater height, positioned at least 10 to 12 feet above the ground to deter climbing animals. Regardless of the location, the box should be mounted with a slight forward tilt to shed rainwater and assist ducklings in climbing the interior wall to exit. The entrance hole should face open water or have a clear flight path to the water.
Methods for Predator Exclusion
A predator guard is necessary for any wood duck box installation. Raccoons and rat snakes are the primary predators of wood duck nests, and they can easily climb unprotected posts or trees. Boxes should never be attached directly to a tree trunk without a guard, and surrounding tree limbs must be trimmed back at least 48 inches from the box to prevent predators from jumping onto the roof.
The most effective barrier is a conical-shaped metal baffle, constructed from 26-gauge galvanized sheet metal. This guard should have a base diameter of at least 24 inches and be securely fastened to the pole or post below the box. The attachment point must be sealed tightly to the post to prevent snakes from slithering between the guard and the support structure.
Annual Installation and Maintenance
Wood duck boxes should be installed well before the nesting season begins, ideally in late fall or winter, to allow the ducks to locate the structures during their pre-nesting surveys. Hens often begin pairing and searching for nesting sites as early as February. The boxes require a specific type of bedding material because the hen does not carry materials into the box herself.
A fresh layer of wood shavings, specifically pine or cedar, must be added to the box floor each year. This layer should be between four and six inches deep and provides both cushioning for the eggs and insulation for the nest. Sawdust should not be used, as it can hold moisture and potentially suffocate the ducklings. Annual maintenance involves removing all old nesting debris, unhatched eggs, and foreign materials, and replacing them with new shavings.