Bluebird Nesting Box Addendum

In last Friday’s blog post, Bluebird Nest Watch, I introduced Frank Zuern, whose many accomplishments include designing one of the more successful bluebird nesting boxes. (They also attract chickadees and wrens.)

Frank’s box is notable for its horizontal form, simulating a broken, hollow tree branch; its minimal rise in interior temperature above the outside temperature (other boxes have experienced major losses during heat waves); and its vertical baffle. Nearly all bluebirds build their nests behind the baffle, away from the entrance hole, to reduce the nest’s vulnerability to predators.

Today’s photo addendum focuses on the box with more of Vicki’s excellent photos. (Thanks again, Vicki.)

Frank is explaining bluebird habits and habitats
 and his bluebird nesting box design.

An often-used nesting box. The entrance hole is on the left.
Nearly all bluebirds build their nest on the right, behind the
vertical baffle. Note the many holes for ventilation, and the
hinged side for monitoring and cleaning the box.

Frank is removing the screws that hold the hinged side closed.

This nesting box has an old bluebird nest behind the baffle (right)
and spillover nesting material near the entrance hole. To avoid a
predator (e.g., raccoon) reaching in and blocking the entrance with
the spillover material, the box must be monitored and spillover
removed. If a new nest is found between the baffle and entrance,
it must be moved behind the baffle after the eggs are laid.

Removing the spillover material uncovers the
vent holes in the bottom of the nesting box.

Frank Zuern’s Nesting Box Design Dimensions (inches)
(refer to photos)

Roof:  8 x 24 x 3/4
Floor:  3-1/2 x 15-3/4 x 3/4
Sides:  5-1/2 x 18 x 3/4 (one side hinged at bottom)
Front:  3-1/2 x 5 x 1-1/2 (thicker wood against predators)
Back:  5-1/4 x 3-1/2
Vertical baffle:  2-1/2 x 3-1/2 x 3/4
Entrance hole: 1-1/2 diameter
Vent holes: 1/2 diameter (see photos for side and floor pattern)

Post is approximately 5-1/2 feet tall. Current design uses a steel fence post within a downspout or PVC pipe (smooth exterior for snake prevention). A wood mounting board, 2-1/2 in x 18 in x 3/4 in, attaches to the unhinged side of the box and slips into the downspout, so the box rests on top of downspout.

While Frank is continually improving the design, a box attributed to him that’s available online has significant design weaknesses. Frank had no patent.

P.S.

Frank would be delighted to communicate with any interested birders or birdwatchers, especially about bluebirds and his nesting box. Please contact me (retirednw@gmail.com) and I’ll forward your note to Frank, who does not have easy access to email.