Housing Shortage in Georgia

When I built my new office behind my garage I wound up with some trees too close to the windows and had them cut down last week. This opened up my view of the backyard and I decided on Saturday to replace a bird house that had been up on a tree since we bought the house years ago. I got a nice $10 cedar bird house at WalMart and attached it to a tree about 10 yards from my closest window. A pair of little somethings adopted it within 1 hour. They have come back several times to check it out. I can only suppose there is a serious housing shortage to have it claimed that quickly. One of the pair has a fairly bright blue back. Gotta look up what they are since they will evidently be neighbors.