This habit of the second female to come to the nest, and if occupied to sit on the existing female occurs several times during the day. Here is another example which occurred at about a quarter past ten.
The habits of the two females were very similar, but I couldn't possibly have expected what follows now!
One female comes to an empty nest box with a beak full of black feathers. She distributes them and goes out again.
Less than a minute later she is back with another beakful.
After arranging them, she settles back into incubation mode.
But what's this? Fifty seconds later, the other female arrives with some black feathers!
Again, she sits on the sitting female ...
... and this time, the incumbent decides that enough is enough - and leaves.
The newcomer seems to be settling down when all of a sudden, ...
... she leaves too!
It appears that what you need to win in these bird wars is bloody minded stubbornness and persistence, not the most powerful fighting technique!
Just to finish for today - here Amy1 ...
... and here is Amy2 - I think!
Joe feeding Amy - I think I'm on safer ground here.
Twelve eggs - yes, I can still count, I think!