This is a slot box version of the large
nest box (Based on the easy-to-make "Tuttle" box)
with the following basics:
Monitors who look into the option of buying or building a slot box
are usually doing so because
they have a House Sparrow problem. Personally, I use only
2-holed boxes on my own trail because that is what I tried (and they
were successful) before learning about slot boxes. If these
large slots work the same as 2-holed boxes, Bluebirds should be able
to escape from the slot opening for continued defense of the box and
chicks. Most other slot box plans are designed with
small interiors and/or shallow depths with the hope they would deter
The floor of this larger slot box will be 7.25" wide by 5.5" with about twice the
room of most slot boxes. See
visuals at Floor Size Comparisons. The slot-to-floor drop
is 9", see Box Depth.
This roomy box can, of course, be modified according to builder
In addition to the large dimensions,
the slot opening and roof are stabilized with lengths of hardwood.
Thus, the slot opening and roof are protected from warping and from woodpecker damage.
need a 2-foot
length of 2"x2"
hardwood to stabilize the upper and lower slot edges. Most slot
box plans specify the roof as the upper edge of the slot opening.
Roofs warp and, thus, the slot opening will change if not
BACK: Three pieces 13" long x 7.5" for the sides
and back. Screw the sides to the back outer edges so your floor
width is the full width of the lumber. A 13" length will provide a
deep (safer) box.
One piece at 5.5" x 7.5" wide for the floor. Screw the floor
between sides/back slightly recessed from the bottom as a drip edge.
The large floor will enable chicks to separate from one another during hot
EDGE: Cut a length of 2"x2" wood to fit between upper sides for slot
and roof stabilization (see photo). This will prevent roof warpage and will stabilize the
critical slot opening dimension. If the slot opening warps, it could
provide access to Starlings or other unwanted competitors or predators.
The upper slat will also provide an "attic" buffer from the hot roof for
adults entering to care for chicks.
Cut one piece 10.5" x 7.5". Then screw on a length of
hardwood trim or a piece of 2"x2" wood to the front door to create a toehold
(see photo) This will stabilize the lower edge of the slot opening and
provide a landing toehold for adults coming in from the outside. It
will also provide extra depth at the lower portion of the opening which will
function as a semi-guard (provide some protection from predators reaching
the door between sides so there is a 1.25" slot opening (or to your
preference to allow desirable birds to enter). There is a variance of
builder preference whether the slot opening should be closer to 1 & 1/8",
or 1 & 3/16", or 1 & 1/4". Eastern Bluebirds are slightly
smaller than Westerns. If the slot is a bit too large, Starlings can
enter and take over the box.
Add two pivot screws so the door swivels upward (or put the pivots at the
bottom, or add hinges to the bottom according to builder's preference).
Add a roof
about 11" x 12"
Add a drip
edge to the roof by inset grooves on the underside or add a slat of wood at
the front (see first photo)
Add a door
hook of your choice
For tips on
waterproofing and sealing the box, please see: Design a Box
(build your own box)