Mary Twitchell - Easy-to-Build Birdhouses

Mary Twitchell

It hardly matters where you live on that one special morning in early spring just before daybreak, your hushed neighborhood will suddenly burst forth into a cacophony of singing, tweeting, chirping, cawing, squawking, warbling. The birds are back, and its time again for their yearly rituals of mating, nesting, and raising a family.

With a little encouragement, some of these avians can become regular seasonal residents (robins, flickers, wrens, sparrows); others (chickadees, titmice, Downy Woodpeckers) may be induced to become year-round companions, providing continual enjoyment for your whole family.

Initially you may learn to identify different species, then their song patterns, nesting habits, and preferred habitats. Soon you will be erecting feeders and setting out birdhouses, or nesting boxes, to encourage birds to feed, court, and breed in your yard.

In cities and in the suburbs where we have converted woodlots, forests, marshy land, and open spaces to housing and asphalt, we have depleted natural bird shelter. Yearly cleanup of brush and dead limbs have reduced the number of sites for nest building. Rows of wooden fence posts, once home to bluebirds and wrens, have now been replaced with metal stakes; and wolf trees formerly left as boundary markers are now mercilessly pruned or removed, especially if they are near power lines. Natural shelter is increasingly difficult for birds to find. Yet attracting birds is beneficial; they love to eat the insects we love to swat. Birds eat many times their weight in insects, keep weeds in check (by eating the seeds), and propagate trees and shrubs by inadvertently dropping seeds in flight.

Whats in a Name?

Although birdhouse is the traditional name for these structures, the more descriptive term often used by experts in the avian field is nesting box. Ill use the terms interchangeably herein.

Of the 650 different species of North American birds, approximately 50 will accept a nesting box in which to raise a family. These species look for a protected, secure home. In their natural habitat, cavity nesters drill out holes in dead branches or tree trunks (chickadees, titmice, woodpeckers); use holes vacated by other birds (wrens, bluebirds, swallows, flycatchers); take up residence in hollows caused by lightning, fungal infection, or insects; or use hidden tree crotches for nest supports (warblers, robins, finches).

Above all, the fledglings of cavity nesters need protection from predators. This means a small, enclosed nesting area and a small entrance hole. However, one size of nesting box does not fit all. Before choosing which nesting box to build, decide which birds you want to attract. Your local Audubon Society can provide information on the bird species in your area.

The materials from which a birdhouse is made play a large part in attracting and safely hosting birds. If you are making your own, starting out with the best of time-tested materials will increase your chances of success; then again, if you are buying a premade birdhouse, you will still want to make sure that it is made of the appropriate materials.

Wood is the best material for constructing a birdhouse. It is readily available and easy to work with. Cedar, cypress, and redwood last the longest but are expensive and may need to be predrilled before nailing. Fir weathers well, but pine is probably the most available. Lumberyards carry -inch (1.9 cm) stock, which is an ideal thickness; it provides adequate insulation from both heat and cold, is durable enough to resist warping, and is easy to use with hand tools. CDX plywood (exterior grade) of -inch thickness can be substituted. Plywoods made for interior use will quickly delaminate, whereas the layers (plies) of CDX are bonded together with a marine glue that can withstand exposure to different weather conditions.

Rough-cut lumber (before it is planed) and slab ends from a milling operation (sawmill waste with the bark still on) are inexpensive, appropriate, and rustic looking. They may, however, demand more ingenuity and craftsmanship if youre to make the pieces fit.

Gourds are a natural substitute. You can grow them in your garden for next years supply of nesting boxes (see page 26).

Box Materials to Avoid

Materials to avoid include metals, plastics, coffee cans, bleach bottles, milk cartons, and PVC drainpipe. All of these are very thin and will heat up quickly. Metal roofs are used on Purple Martin houses (to lighten the construction) and sometimes on Wood Duck houses (to protect against raccoons) but should be avoided on boxes for other birds. Also avoid wood treated with preservatives and plywoods made for interior use.

To increase the life of the nesting box, glue all joints before nailing or screwing. The glue will give a weathertight fit and hold the boards together over time. Use an exterior grade of wood glue; it will be yellow in color and is waterproof. The glue will not bond, however, if any of the surfaces have been painted or varnished.

Galvanized nails will last longer than steel ones; ring-shank nails will hold better than smooth nails. Brass or stainless-steel plasterboard screws are long lived, resist corrosion, and do not stain the wood; brass hinges are preferable to steel ones. Use screws, not nails, when attaching boxes to trees or posts to make seasonal removal easier.

Construction Tip

After nailing the boxes together, check to make sure that none of the nails protrudes into the cavity and that all joints fit tightly. Birds can catch, or even break off, a claw in a crack left between boards.

There is no need to paint your birdhouse, but if you wish to, use an exterior, water-based (latex) paint. Never paint the entrance it makes it difficult for birds to get a good foothold. And never paint or stain the inside of the box, as the chemical fumes are hazardous.

Purple Martin houses, unlike other nesting houses, are very exposed in that they are mounted in open areas 10 feet (3.1 m) off the ground. Thus, their roofs are painted white to reflect the heat. All other birds, however, will avoid a white box; to them it means a more conspicuous home, hence more obvious to predators.

If you decide to paint, use dull, drab colors such as green, gray, tan, and light brown and do the painting in fall so that all vapors will have dissipated by spring. The wood may also be treated with a nontoxic linseed oil.

Although each species has its own specific requirements, all bird-houses should provide the following:

Shelter

Protection from the elements (wind, rain, intense sun)

Ventilation without drafts

Insulation

Drainage

Durability