Empty Birdbox

[Axeman]

Just a question -- do you clean birdboxes out once they're done for the season or let them be ?

The reason I ask is, I have a swallow box, and many years ago I had tree swallows nesting in it. I cleaned it out and they never came back. Now it's  used by wrens. Don't get me wrong, I enjoy the wrens but prefer they use the wren boxes which now sit empty.

[Leslie Kinrys]

I believe you should clean out your boxes at the end of the season. As for your lack of Tree Swallows that could be due to the wrens. Wrens can be quite aggressive defending a nest box. They will destroy the eggs of another species. So, they could have made your swallows move on.