Northern Prairie Wildlife Research Center
Figure 1. The single compartment wood nest box is easy to build. If properly placed and maintained, these boxes can provide secure nest sites for the cavity nesters in your area for many years.
When constructing the nest box (Figure 2), it is advisable to use nails that are long enough to hold securely despite rough handling and weathering. Hot dipped or ringed galvanized 8-penny or 10-penny nails are best. Depending on the condition of the wood used, it may be necessary to drill pilot holes to avoid splitting the wood.
It is important to bore four 1/4-inch drain holes through the bottom of the nest box. The floor of the box should be recessed 1/4-inch up from the lower edge of the sides to retard rotting.
Figure 3 shows four design variations which can be used to provide easy access for inspection, cleaning and general maintenance. These variations are a top hinge, a top cleat, a side hinge and a side pivot design. The two variations employing side door opening designs should be used in situations where it would be either difficult or impractical to service the nest box from above.
As shown in the plan, the entrance hole should be an oval, 3 inches high and 4 inches wide for wood ducks, hooded mergansers and buffleheads, and 3 1/2 x 4 1/2 inches for common goldeneyes. This hole excludes most raccoons. The hole should be centered about 19 inches above the floor. A 3- to 4-inch x 14-inch strip of 1/4-inch hardware cloth mesh should be attached inside the box under the entrance to function as a ladder when the newly hatched ducklings leave the box (Figure 4).
Figure 4. A 3- to 4-inch x 14-inch strip of 1/4-inch hardware cloth mesh attached to the inside of the box under the entrance hole serves as a ladder to assist newly hatched ducklings in leaving the box.