Judging from the position this bluetit has adopted, there is something upsetting it outside the box.
Yes - another bluetit is at the entrance. At least it's not a woodpecker!
Still, it looks cautious, but it is not in full defence mode!
Aha! Now this one's going into the box too!
A first for the year I believe - apart from the fight in Box3 of course. But this appears a friendly visit - no sudden movements, no feathers raised etc.
Five seconds later they are both still there. This is definitely a potential pairing!
A few more seconds, though, and one of the two birds leaves.
Away!
... leaving one pensive looking bluetit.
Theoretically, this should be the female and the departed bird the male. However they both look the same to me so I couldn't say that from the way they look.
It is now over half an hour later and you can compare that sequence with this one. Again we start with one bluetit already inside the box.
After 20 seconds, another bird arrives at the entrance ...
... and quickly enters the box.
Immediately there is a great commotion ...
... and a bluetit immediately leaves.
This one's off.
Why the difference? Is it just one of those things, or is there a reason for the different behaviour? Although it's the same box, perhaps they are different birds.