Northern Prairie Wildlife Research Center
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; fig. 1 provides one example. 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 (see fig. 2). The predator guard should be placed 6 to 12 inches below the bottom of the box.
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.
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. For Wildlife Habitat Council member organizations, the monitoring program may enroll in WHC's Nest Monitoring Program, useful in WHC's Corporate Wildlife Habitat Certification Program. Enrollment can be accomplished by contacting the WHC Nest Monitoring Program Coordinator at (301) 588-8994.