I have a question about nesting bluetits. We have a birdbox which was occupied by a pair of bluetits. They flew in and out all day long for several weeks. We assumed that there were eggs and then babies inside. We watched every day. Each bird would arrive via various twigs around the nestbox before entering the box itself. They seemed to have food in their beaks and they took it in turns to go into the box and out again. Then suddenly they stopped coming. We didn't know whether the babies had died. Finally, we took the box down and opened it. There was absolutely no sign that there had ever been a nest. No bedding, dead birds or eggs. Although we have loads of tits using our bird feeders on the other side of the garden none have approached the same side as the nestbox. Could the babies have fledged while we weren't looking? Do bluetits empty out nest materials when they abandon the box? Any ideas?