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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. Bird toeholds are created with beads of Liquid Nails adhesive which adhere very well to the PVC. Liquid Nails is also used to seal off the bottom of the nest cavity for sanitary purposes. With the large roof overhang, the cavity stays bone dry.

The 5 in. portion of thinwall just below the bottom block is protected from wind and rain. It is a good place to apply an ant stop such as Tanglefoot or STP Oil Treatment if needed. This box should also prove to be mouse proof.

I set two bird boxes up in a friend's yard which has continuous visits from cats, opossums, and raccoons. The box was baited with food at various levels. Food placed in the upper six inches of the box was never reached by predators.

Nine buoy bird boxes were used in the field during the 1 996 and 1 997 seasons. They were added to nine existing PVC slot and eight wood-slot bird boxes located at two golf courses. Successful bird box use at these two sites is charted below. Some bird boxes had multiple uses during the seasons.

This article was reviewed by the NABS Technical Advisory Committee. Their questions and concerns are addressed below:

ROOF MATERIAL: This is a never ending story. Many materials can be used. (pie tins, Frisbees´┐Ż, cedar wood, etc.) It is true that plastic bucket lids are prone to deterioration. I selected bucket lids as an expedient. They are free and I didn't have a better idea. My criteria for the roof is twofold: 1 . a large overhang on ' all sides to provide about three hours of full sun for the nest cavity; 2. a white color. White reflects almost all heat energy. Even metal painted white doesn't get hot. I say "White is right' I am now trying a 14 in. square piece of white aluminum flashing folded over a 12 in. square of 1/4 in. plywood. It should last a long, long time.

SECURITY OF NEST CAVITY: My preference is easy access to the nest cavity. For this reason, I use only a pin (nail) to keep the door secure. A screw can be substituted to discourage tampering by curious people.


Table 1.
Successful use of bluebird buoy, slot and PVC boxes by five bird species 1996 and 1997.
Box Type Number Eastern
Chickadee Tree





















COST: 4 in. PVC sewer pipe costs about $ 3.7 5 per 1 0 foot length. This works out to be about $1.25 per box.

PAINT COLOR: The sewer pipe is available as either white or gray PVC. I now use gray pipe and don't paint it. When I used white pipe, I spray-painted it brown because I like the color.

COMPLICATED TO BUILD: Not really. Maybe the first one will be slow to construct. After that, they pop out like hot cakes. Ron Olsen's Boy Scout troop 403 of Addison, Illinois built 38 of them last winter. Everything can be improved or simplified. For example, I plan to eliminate the "front slot." The 'door' will be shortened to 6 in., then located to a position where a 1-1/8 in. gap exists between the top of the "rear slot" and the top of the "door.' Bird entry will be via this gap. The guide notch and pin will be relocated to the bottom of the door.

NAME: It was suggested that calling this bird box a "buoy" may be meaningless to most bluebirders. I recall that when I first joined NABS, I didn't know what a 'Sialia' was. But I learned that Sialia was both an appropriate and a beautiful name for our journal. I feel the same about buoy. A buoy is used on waterways to mark safe channels to guide ships safely to harbors and home. Likewise, this bird box not only looks like a channel marker buoy, but it also is a guide to a safe harbor and home for bluebirds.

My hope is to have other people construct this box and try it out. I want to know if it really defeats raccoons. I would also like to hear about changes to the design that could simplify construction or improve function.

2323 So. 14th Ave.
North Riverside, IL 60546

Frank Navratil and his bouy boxConstruction drawings

Frank Navratil, North Riverside, Illinois, with his bluebird buoy bird box.


Reprinted, with permission, from "Sialia/Bluebird" Journal of the North American Bluebird Society. NABS is a membership organization for persons interested in bluebirds and other North American birds which use cavities for nesting. For membership information, send a message to membership@nabluebirdsociety.org or go to the NABS web site at http://www.nabluebirdsociety.org/ 


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date of last change 01/20/15Web space provided by the Audubon Society of Omaha.