Wood is just about the best building material for any birdhouse. It’s
durable, has good insulating qualities and breathes.
Three-quarter-inch thick bald cypress and red cedar are recommended.
Pine and exterior grade plywood will do, but they are not as durable.
It makes no difference whether the wood is slab, rough-cut or
finished, as long as the inside has not been treated with stains or
preservatives. Fumes from the chemicals could harm the birds.
There’s no need to paint cypress and cedar, but pine and plywood
houses will last longer with a coat of water-based exterior latex
paint. White is the color for purple martin houses. Tan, gray or dull
green works best for the other cavity nesting species. The dull, light
colors reflect heat and are less conspicuous to predators. Don’t paint
the inside of the box or the entrance hole.
Regardless of which wood you select, gluing all the joints before you
nail them will extend the life of your bird house. Galvanized or brass
shank nails, hinges and screws resist rusting and hold boxes together
more tightly as they age.
[Illustration: Suspended wooden nesting box]
Resist the temptation to put a metal roof on your bird house.
Reflective metal makes sense for martin houses up on a sixteen-foot
pole, but when it’s tacked onto the roof of a wood chickadee house,
the shiny metal is more likely to attract predators.
Natural gourds make very attractive bird houses. They breathe, and
because they sway in the wind they are less likely to be taken over by
house sparrows and starlings.
Grow your own gourds and you’ll have dozens to choose from in the
years ahead. If you don’t have the space to grow them, a coat of
polyurethane or exterior latex (on the outside only) will add years to
the one you have.
Properly designed pottery, aluminum (for purple martins only),
concrete and plastic houses are durable, but don’t drop them.
Be sure to provide ventilation, drainage, and easy access for
maintenance and monitoring. Concrete (or a mix of concrete and
sawdust) offers protection other houses cannot: squirrels can’t chew
their way in.