Because bluebirds lack a strong bill to excavate a cavity for nesting, they depend on finding the used cavities of other birds or man-made houses. Bluebird populations had declined steadily over the years due to habitat loss. But, thanks to man-made houses, they are making a comeback. Our Wild Birds Unlimited bluebird boxes are designed with the birds in mind.
The top can be lifted for viewing without disturbing the nestling and easy monitoring of the nest-(it is not recommended to open the box day 13 or after as this may cause fledglings to leave the nest too early). The side is easily opened at the end of the nest season for cleaning. It is important to clean out old nesting material that may harbor parasites.
Mounting Bluebird BoxesLocate in an open, grassy field edge or lawn area away from trees (300 ft or more apart). Place the houses at least 50 feet away from birdfeeders and your main house. Face the box away from prevailing winds (facing south) and mount boxes approximately 5 feet high. Perching areas near to the nestbox like telephone poles, stakes, small trees, etc. are preferred by bluebirds.
Have boxes up by March in mid-Michigan.
If Tree Swallows compete for the nest site, place another box near the first (15 to 25 feet from the original house). They seem to tolerate overlapping territories of other species, but bluebirds will not nest less than 100 feet from each other. Both swallows and bluebirds are dependent on cavities for nesting, but otherwise they are different in many of their survival strategies. Bluebirds feed on ground-dwelling insects while swallows feed on insects in the air. Given places to nest, they can coexist within an area quite effectively. It may even be beneficial for bluebirds to have swallows nearby to warn them of potential predators or danger.
One important item to mention is that sparrows and wrens may try to take over a bluebird nesting box. They may find the box first or they may try to force the bluebirds out. The only way to help reduce this possibility is to make sure the house is mounted away from the edge of trees or away from human dwellings and to remove the nests before they are complete (a sparrow nest is a sloppy collection of grasses or litter that fills the box. A wren builds its nest out of twigs). You can also leave the top and side of the nestbox open to make it less desirable until the sparrow relinquishes its claim on that house.