Sitting tight

We have just completed our first nest box inspection in the wood and there is a substantial % occupancy  this year - mostly Blue and Great Tits but two Wrens, one Coal Tit and four boxes with Pied Flycatchers. At this stage, incubating adults are so unwilling to stop what they are doing that the roof coming off their 'home' is not a sufficient disturbance to make them budge an inch and they remain hunkered down, just staring up at the intruder - a mark of their determination to protect their precious eggs. In some cases there was a complete clutch but incubation had not begun. So the first photograph shows a female Pied Flycatcher sitting tight and the second is a separate box where there was no bird incubating at the time of inspection. Roofs were quickly replaced with minimal interruption.