Why no takers?

Some weeks ago, when the swifts started arriving from their long journey, I had to keep chasing the little chaps out of our garage, which is tall and has a spacious attic.  So I ordered a swift box, expecting, hoping, that a loving couple would take advantage of my generosity.

But no joy.  And today another pair zoomed into the garage when the door was open for a few minutes; why won't they take my hint?

The box is from "Homes for Woodland Folk" on Etsy and is very well made.