Nesting birds are often very territorial. As such, when one pair spots another pair of the same species trying to nest too close to their nesting site, conflicts emerge. With that in mind, one of the reasons why birds do not use birdhouse in some yards is boxes are placed too close together. When nesting boxes are packed in too closely, some birds of the same species will fight with one another and sometimes end up not nesting at all.
With this in mind, here is a list of some of the birds that commonly nest in Georgia backyards and the recommended spacing between boxes designed avoid territorial battles.
Eastern Bluebird – Minimum of 100 yards.
Carolina Chickadee – 30 feet
Tree Swallow – 35 feet
Tufted Titmouse – 580 feet
Carolina Wren – 330 feet
House Wren – 100 feet
Great Crested Flycatcher – 1 box per 6 acres
Brown-headed Nuthatch – 1 box per 6 acres
Keep in mind that some species tolerate birds of another species nesting close to their nest. For example, eastern bluebirds will allow Carolina chickadees to nest well within 100 yards of their nests. In this case, if a Carolina chickadee nest box is equipped with an entrance hole measuring 1 1/6th of an inch in diameter, bluebirds would never try to nest in a birdhouse with an entrance hole that small.