The Audubon Society Of Omaha Navratil's Bluebird Buoy Bird Box Frank Navratil Acceptance by Eastern Bluebirds of PVC slot entrance boxes designed by Steve Gilbertson led me to an evolution of the design. Combining a predator guard with the slot entrance box during initial construction resulted. All the basic parts of the box are already field-proven. The completed box reminds me of a nautical buoy, hence the name.
Maintenance is minimized by eliminating exposed wood.
Recycled plastic is used for the roof and scrap wooden 2X4s are used for internal construction. The box body and door are cut from 4 in. PVC sewer pipe. Mounting is Gilbertson's method of electrical thinwall pipe slipped over a rebar driven into the ground. The sliding door allows easy and convenient access to the entire nest cavity.