Wood ducks are one of the few North American duck species that nest in tree cavities. The decline of mature forests has made artificial nesting boxes a successful conservation tool. Providing an artificial cavity is only the first step toward successful breeding, however. The location of this structure directly influences its use by hens, the survival of eggs, and the safety of newly hatched ducklings. Proper placement, from habitat selection to the exact mounting method, is the most important factor for a successful wood duck nesting season.
Ideal Habitat and Water Proximity
Wood duck hens seek nesting sites that mimic their natural, wooded wetland habitat. Ideal locations include wooded swamps, flooded timber, marsh edges, beaver ponds, and small lakes or river coves with ample surrounding cover. Emergent and dense plant cover is important because it provides immediate cover for ducklings after they leave the box.
Boxes should be placed relatively close to a water source, as the hen must lead her brood to the water within 24 hours of hatching. Although wood ducks may nest up to a half-mile from water, greater travel distance increases the ducklings’ mortality risk from predators. Place boxes on land within 25 to 200 yards of the shoreline, or directly over shallow water.
When placing boxes over water, the depth should be shallow enough for ducklings to forage but deep enough to deter ground-based predators; 2.5 feet is often considered ideal. The area between a land-mounted box and the water must be clear of obstructions like roads or fencing that would impede the ducklings’ journey. For maximum usage, the site should contain water year-round or throughout the spring and summer nesting season.
Mounting Location and Height
The physical mounting location should prioritize stability, accessibility for maintenance, and predator avoidance. The two primary options are sturdy metal posts or pilings placed over water, or on trees on land. Mounting over water is often the best option because it significantly reduces the threat from terrestrial predators like raccoons and snakes.
When mounting over water, position the bottom of the box at least four feet above the expected highest water level to prevent flooding and keep it out of reach of swimming predators. For boxes installed on land, the minimum recommended height is 6 to 12 feet above the ground. This elevation helps deter predators and human disturbance, though a minimum of 10 feet is often suggested for land mounts.
If mounting to a tree, choose a large, stable trunk and use non-girdling hardware, such as lag bolts with a backing board, to allow for tree growth. Mounting on a metal pole or treated wooden post is preferred over trees, as it allows for the attachment of a predator baffle. The pole or post must be securely fixed, buried 24 to 36 inches deep, to ensure the box remains stable; hens may reject loosely hanging structures.
Orientation and Density
The direction the box entrance faces influences its use by hens and the internal temperature. Ideally, the entry hole should face open water, allowing the hen to easily spot the box while flying or swimming. Facing the entrance toward the north or east is recommended, as this orientation helps avoid excessive direct sunlight that can cause the box to overheat during the late nesting season.
Maintain a clear, unobstructed flight path of at least 40 inches in front of the box entrance by trimming back encroaching tree limbs or brush. Spacing between nesting boxes is important to prevent “dump nesting,” where multiple hens lay eggs in the same cavity. Dump nesting often results in a clutch too large for one hen to incubate successfully, leading to nest failure.
To avoid dump nesting, boxes should be placed at least 50 to 100 yards apart, or positioned completely out of sight from one another. Placing more than one box on a single post is discouraged, as clustering increases competition. A density of approximately one box per acre of suitable brood-rearing habitat is recommended.
Essential Predator Protection
Predator protection is necessary for wood duck nesting success, and strategic placement is the best defense. Common predators include raccoons, rat snakes, mink, and squirrels, which are adept climbers. Avoid placing boxes near fences, leaning trees, or low-hanging branches that could provide a bridge for predators to access the box without climbing the mounting structure.
The most effective protective measure is installing a predator baffle on the mounting pole or post beneath the box. Conical metal shields, constructed from at least 26-gauge sheet metal and measuring at least 36 inches in diameter, are effective against climbing mammals. The baffle must be secured so it is free to wobble, which discourages climbing, and the top should be at least four feet above the ground or high-water mark.
For boxes mounted on wooden posts, a stovepipe baffle—a smooth, cylindrical metal pipe—is an alternative that works well against raccoons and snakes. The baffle must be installed directly on the pole, not on the box itself. Any gaps between the baffle and the post must be sealed to prevent snakes from squeezing through. Never mount a box without a predator guard, as this often turns the box into a predator feeding station.