The Nesting Box War
Both Eastern Bluebirds and Tree Swallows visit us at Distant Hill every spring. We have six bird boxes for them to nest in, but there is a problem - they will compete for the same box. It turns out there is a way to alleviate the problem. Bluebirds will not let another pair of bluebirds nest within about 300 feet. Tree Swallows defend a range of only about 20 feet from other nesting Tree Swallows. However, both will allow other species of birds to nest within there defended range.
The trick is to place the nesting boxes in pairs, no more than 5-10 feet apart. Each pair of boxes should be at least 300 feet from the next pair. Too many boxes in one bluebird territory may attract groups of swallows that can mob a lone pair of bluebirds. If swallows use one of the paired boxes, they will allow bluebirds to nest next to them, but not other swallows. With the next pair of boxes being 300 feet away, these can also accommodate both swallows and bluebirds, without attracting too many Tree Swallows. Everyone is happy!
The Tree Swallow Nest Box Project describes the box location in detail, along with lots of photos and info on building nesting boxes that work best for tree swallows.
The North American Bluebird Society website has plans for a number of different bluebird nest box designs.
I have to go out now and place my nesting boxes in pairs. I'll let you know if it works...
UPDATE...Moving the birdhouses WORKED!
Here is Photographic Proof that the Nesting Box War is over.