We start with a bird in Box1. It has its beak open so is probably calling to its partner outside. But is it the male or the female?
More nesting material!
In comes the female, so the bird in the box must have been the male.
We know the incomer is a female because she is carrying some nesting material - and male bluetits do not help with nest building!
(The sooner we can give this pair some names the better!)
The male moves forward to get out of the way and the female flings her load to the floor of the nest box.
The male then leaves.
Just two seconds has elapsed since the first picture at the top of this page was taken. The female is now alone in the box.
Bluetits never seem to place their nesting material as some species appear to do. They just throw it anywhere and rely on their movements to mould it into shape. Towards the end of nest building, they will help the nest cup development by standing where they want the nest cup to be and lifting bits of nest material to the edges of the box, but that's about all there is to nest construction here!
There was no more nest building activity today.