Rapping, rapping - first on the back wall, then on the roof; finally a little downy woodpecker came into view where he'd been testing the resonance of his drumming on a vacated bird house; when no bird came out the front door, in went the downy - to try out the sound from inside! This house provided shelter to tree swallows that raised two broods this summer. Perhaps this little bird was auditioning the house as a winter shelter.