We don’t have Purple Martins, but we do have barn swallows. Very similar bird in the Martin family. Often confused with purple martins because they both soar around eating bugs.

Ours were scared off by a raccoon family last year but I am glad to report that the birds are back in full force this year.

Looking at your picture, is there a way to orient the houses so the bulbous portion is down? Purple Martins nest in hollowed out gourds in nature. Most of the style we have around here hang down like gourds. Just a thought.