On approach to these boxes in previous years the adults have invariably left the nest before or whilst the ladder is erected and the box opened. Even whilst examining the first box, the remaining boxes are normally vacated too. This year, of 8 occupied nests, 5 still had a sitting adult after the box was tapped quite vigorously and opened up. The progress of these nests was not recorded since it is unwise to touch or lift this species from the nest.
We have experienced an extremely cold and windy early spring so far and, subjectively, it did seem that the nests were particularly bulky this year, with the boxes being completely packed with material and nest cup very close to the base. It seems possible that this, together with the tightly sitting adults, may be a result of the cold conditions and that the birds have reacted to the weather to provide maximum protection for their eggs and young.
In those nests where the adult was not sitting, the development of eggs and young was only slightly behind last year in spite of the cold and windy conditions this spring. The progress of the 5 nests will hopefully be revealed once feeding begins.