Why do Tree Swallows use nest boxes?
Cavity-nesting birds like Tree Swallows, that can’t make their own cavities, usually face a shortage of nest sites. Competition for cavities can be intense, even a matter of life and death, since failing to reproduce is a critical failure for short-lived songbirds. Tree Swallows must compete for nest sites with other Tree Swallows and also with other cavity-nesters like bluebirds, wrens, starlings and house sparrows. Since natural cavities are scarce Tree Swallows quickly accept nest boxes, and unlike many other cavity nesting species they aren’t picky! They’ll use just about any box they can get into. Their nests have been found in large houses for Purple Martins, Wood Ducks and Screech Owls, and in such unlikely spots as drain pipes, mailboxes and newspaper tubes (see the photo below by Laura Niang). Sadly, they’ll also try to nest in unsuitable tiny or flimsy boxes where few if any young survive. Be sure to build boxes designed specifically for Tree Swallows. You’ll want boxes like
