Guide to Building a Bird House

What Makes a "Good" Bird House?

Homemade or store-bought bird boxes provide a much needed place for cavity nesting birds. Cavity-nesters are birds that seek out holes in trees to lay their eggs and raise their young. Some examples are the nuthatch, brown creeper, wood duck, prothonotary warbler, bluebird, chickadee, owl, purple marten, wren, and of course the woodpecker. Woodpeckers create some of the holes in trees; other holes occur when limbs fall off trees, when insects and disease attack a tree, and when fungi decompose what's left.

Unfortunately, most Americans have a traditional European land ethic which dictates that everything growing in their yard or on their property must "look clean," and the first thing to go when a house is built are any standing dead trees. This means a shortage of suitable nesting sites for cavity-nesters.

You can help cavity-nesters by putting up a bird house that has been specially designed for them. Because each species is unique, they each have particular requirements, such as the size of the opening or how high up from the ground it is. It is extremely important to locate the bird box in the correct habitat for that bird, too, if you have your heart set on attracting a particular species. Mounting a bluebird house near any buildings or other structures, for example, will almost certainly be taken over by a house sparrow—a non-native species that competes with our native cavity-nesters. Starlings should also be discouraged from using any box you put up.

Here are some pointers to look for when purchasing or building your own bird house:

  • The box should have ¼-inch holes or larger in the bottom for proper drainage
  • There should be holes or spaces on the sides of the box near the roof for adequate ventilation
  • The box should be constructed of wood at least ¾-inch thick and preferably 1-inch thick to insulate nesting birds from the heat
  • The roof should overhang the front of the box a good two inches to shelter the opening from wind and rain
  • If the box is painted, it should be painted in a light color to reflect heat; clear varnish works fine
  • Check to see that the back of the box is long enough to make it easy to mount to a post, or that some provision is made for easy installation
  • Do a little reading about cavity-nesters first: you're building homes for future generations!