Building your own bluebird box can be fun and makes an excellent family or school project. Visit the North American Bluebird Society Web site for plans on building your own box.
Many commercially produced boxes are also available and are produced with the preferred size and entry hole size to encourage nesting.
House cats and raccoons are among the most serious predators. A house with a large slanted roof and overhang can prevent the cat or raccoon from reaching over and into the nest box.
If raccoons or other predators are present it is better not to mount your box on a tree or fence post, where raccoons are more likely to locate the next box.
It is often a good idea to place a shield or hardware cloth under the box to prevent snakes and other animals from entering the next box.
Nesting boxes should be mounted so the entrance hole is five to six feet above the ground.
Face the box away from prevailing winds.
Ideally, boxes should face toward a tree or shrub which is within 100 feet of the box. This provides easy access for young birds leaving the nest.
Eastern Bluebird - Boxes should be spaced at least 100 to 150 yards apart. Some experts recommend placing boxes in pairs about 25 feet apart, with the pairs then 100-150 yards apart. Western and Mountain Bluebirds - Boxes should be spaced about 300 yards apart.
Bluebird boxes should typically be in place by mid-March (early March in southern states where bluebirds are year round residents), but may also be put up later in the nesting season.
Here are a few other bits of useful information that will help you plan and manage your bluebird box:
Bluebirds usually nest in late March or early April. In the southern US bluebirds are resident throughout the year and may nest earlier.
Bluebirds usually have two broods per season, with three broods a possibility.
Bluebirds typically lay 4 to 5 light blue eggs, but as many as 7 is possible. Some eggs may be white.
The incubation period is 12 to 14 days.
Young birds remain in the nest 18 to 21 days before they fledge.
Remove bluebird nests, clean out the nest box and close it after you are sure nesting is complete for the season. Remember that two or even three broods may be raised. Wait several weeks after the first brood has left the nest to insure that it will not be used again that year.
A bluebird nest is a cup-shaped and is usually made up of 100% woven grass.
A house sparrow nest is a thick collection of grass, weeds and junk and can fill the entire bluebird house. Remove signs of a house sparrow nest immediately.
It may take several seasons for bluebirds to locate and select your nest boxes but your patience will be well rewarded when you find your first resident. Their sweet calls and shimmering beauty are well worth the effort.