Navratil's Bluebird Buoy Bird Box
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�, 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
Successful use of bluebird buoy, slot and PVC boxes by five bird
species 1996 and 1997.
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
2323 So. 14th Ave.
North Riverside, IL 60546
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
or go to the NABS web site at