I am baffled. For 9years we have had many Eastern Bluebirds use our box for nesting 2-3 times a season. They generally start mid February or early March. We are in Central Texas (Austin) and this is the first year we have had none using the box- and more odd is that no bluebirds seems to be around at all! Nothing has changed that I know of… still water sources and plenty of bugs. Any ideas??
If your nest box is still vacant I would wait and see what happens. Here in Pennsylvania I usually get bluebirds nest-building in my box the first week of April. One year none showed up until the middle of May. There’s still plenty of time for them to show up in your neck of the woods. If not for a first brood then hopefully for a second or third brood.